1. PRONE
WHITE
PAPER POSITIONING
OF PATIENTS ON OPERATING ROOM
SUPPORT EQUIPMENT:
INTRA-OPERATIVE COMPLICATIONS
Author: Helen M. Manson, MB ChB MRCGP (UK)
ABSTRACT: This paper summarizes the complications related to positioning devices used to support patients during prone surgery. The
surgical patient’s position must allow the surgeon optimal access to the operative site, but it can unduly influence the patient’s recovery time,
morbidity and mortality. The types of complications associated with the prone position include: cardiopulmonary, central nervous system,
pressure, ophthalmological, and oropharyngeal. These complications can have serious consequences for the patient, leading to pain, disability,
paralysis, visual loss, or even death. The methods used to support the prone patient influences the occurrence and severity of complications.
The design and ergonomics of the positioning equipment, in conjunction with staff education on proper techniques for positioning the patient,
is vitally important.
“The successful outcome of surgery on the thoracic and lum- reflexes. Enforced immobility during surgery, often for a long
bar spine is largely dependent on the proper positioning of the duration of time, combined with drug-induced loss of tissue
patient before the operation begins” (Iqbal Singh, M.D, The tone, changes in tissue mass associated with aging,
Prone Position: Surgical Aspects, 19871). This fundamental co-existing medical conditions, the physiological consequenc-
premise is important: careful positioning not only allows the es of being prone, and inadvertent pressure on the abdomen
surgeon optimal access to the operative site, but also influences while prone, can lead to many complications. The patient’s ori-
the patient’s recovery time, morbidity and mortality. Numer- entation on the operating table, the type of device used to sup-
ous commentators have described the range of complications port the patient in the operating room, and the way in which
resulting from improper prone positioning.1,2,3,4,5 Sengupta and positioning devices are used by staff are also known to poten-
Herkowitz write in Complications of Pediatric and Adult Spi- tially influence the occurrence and severity of certain complica-
nal Surgery (2004): “Proper positioning of patients is one of tions.2,3,4,5,6 Support devices include operating room tables or
the most challenging tasks in spinal surgery. Air embolism, pe- table frames, kneeling attachments, pads, rolls, blankets, safety
ripheral nerve palsy, blindness, quadriplegia, compartment syn- belts, arm supports, mattress overlays and head supports.
drome, pressure necrosis of the skin, excessive bleeding, and
venous thrombosis are only some of the complications that This paper summarizes the intra-operative complications relat-
may result from improper positioning.”6 ed to positioning devices used to support patients prone, with
particular reference to spinal surgery. This summary is based
The prone position is a natural posture often adopted during on an extensive literature search of Ovid Medline, conducted
sleep, when protective involuntary alterations in posture coun- in January 2008. Search terms included combinations of the
teract postural atelectasis, ischemia, nerve compression and following terms: “prone”, “position”, chest”, “breast”, “ im-
skeletal stress.1 Anesthesia leads to loss of these protective plant”, “rupture”, “spine”, “spine surgery”, spinal surgery”,
Copyright 2009, Allen Medical Systems. D-770490-A1 Oct. 22, 2009

2. “breast pain”, “anesthesia”, “complications”, “pressure ulcers”,
“visual loss” and “nerve injury”. The reference lists of those
1. CARDIOPULMONARY EFFECTS
papers found in the initial search provided additional sources
OF THE PRONE POSITION
of information, and a library search was also conducted to find Prone positioning during anesthesia is associated with pre-
relevant textbooks. dictable changes in cardiopulmonary physiology. The way
in which the patient is positioned, the type of support de-
Several authoritative sources were found that provided an over- vices used, together with certain characteristics of spinal
view of prone complications. Martin has written an evidence- surgery can combine to magnify the impact of these physi-
based summary on prone positioning, supplemented by his ological effects on the hemodynamic and respiratory systems.
extensive experience as an anesthesiologist, in: Positioning in
Anesthesia and Surgery (edited by Martin and Warner, 1997).2 Inferior Vena Cava Obstruction
Sengupta and Herkowitz describe these complications in detail In the prone posture, pressure on the abdomen compresses
in the context of spinal surgery, in Complications of Pediatric the inferior vena cava (IVC) and femoral veins, diverting blood
and Adult Spinal Surgery (edited by Vaccaro, 2004).6 Edgcombe from the distal parts of the body into perivertebral venous
et al have recently published a comprehensive review paper plexuses. This makes wound hemostasis difficult and obscures
summarizing the evidence underlying the complications of an- the surgical field. The great vessels and small bowel are at risk
esthesia in the prone position (2008).3 The Association of pe- of being pressed against the lumbar spine by raised intra-ab-
riOperative Registered Nurses (AORN) has also characterized dominal pressure, increasing the risk of accidental iatrogenic
the complications of prone positioning, producing important injury to these organs during spinal surgery.2,3 IVC obstruc-
guidelines to aid prevention.4 These sources describe the range tion from pressure on the abdomen can therefore potentially
of complications related to techniques used to support patients reduce cardiac output and also contribute to blood loss.
in the prone position, summarized in Table 1, and further dis-
cussed in this paper. Different positioning devices have been designed to maximize
operative access while minimizing pressure on the abdomen.
TABLE 1: THE RANGE OF COMPLICATIONS ASSOCIATED WITH PRONE POSITIONING DURING SURGERY
COMPLICATION DESCRIPTION
Decreased cardiac index, inferior vena cava obstruction, venous gas embolism and non-
Hemodynamic effects
gaseous embolism.
Respiratory effects Decreased respiratory compliance (in the presence of abdominal compression).
Ischemic cerebrovascular events (due to occlusion of the carotid or vertebral arteries); neu-
Central nervous system injury rological deficits related to venous occlusion, air entrainment, pneumorrhachis, or cervical
spine injury; triggering of symptoms from undiagnosed space-occupying lesions.
Pressure injury: Skin Pressure ulcers, contact dermatitis, compression of the pinna, viscerostomy damage.
Pressure injury: Chest Tracheal compression, mediastinal compression.
Hepatic ischemia, pancreatitis, acute mesenteric ischemia; limb compartment syndrome and
Pressure injury: Vascular supply
rhabdomyolysis; avascular necrosis of the femoral head.
Pressure injury: Bone & joints Shoulder injury, bone and joint pain.
Pressure injury: Breasts & genitalia Pain, bleeding, implant rupture.
Brachial plexus, ulnar, axillary, musculocutaneous and radial nerve compression; lateral
Pressure injury: Peripheral nerve femoral cutaneous nerve injury (meralgia paresthetica); facial nerve injury; penile nerve
compression; supraorbital neuropraxia.
Corneal abrasion, chemosis, ischemic optic neuropathy, central retinal artery occlusion,
transient or permanent ophthalmoplegia, cavernous sinus thrombosis, central retinal vein
Ophthalmological complications occlusion, orbital hemangioma, orbital compartment syndrome, bilateral angle closure glau-
coma, non-traumatic subperiosteal orbital hemorrhage, amaurosis, dislocated intraocular
lens, fixed mydriasis, cortical blindness.
Oropharyngeal complications Nasopharyngeal congestion, salivary gland swelling, macroglossia, oropharyngeal swelling.
Loss of body heat Hypothermia
2 Copyright 2009, Allen Medical Systems. D-770490-A1 Oct. 22, 2009

3. These support devices have varying effects on intra-abdomi- or negative pressure may draw in air intravascularly from a sur-
nal pressure. Schonauer et al found, on literature review, that gical wound. Efforts to minimize abdominal compression in
differences in intra-abdominal pressure and the extent of the prone position can result in an increased negative pressure
blood loss are linked to the patient’s position, and vary ac- gradient between the right atrium and veins at the operative
cording to the table or frame used during spinal surgery in site. The low pressure in the IVC results in a negative pressure
prone patients.10 which could then move gas from the operative site to the right
atrium. Air embolism has been reported infrequently follow-
A rise in intra-abdominal pressure may be caused by factors ing surgery in the prone position, described in the published
other than the table or frame, such as sandbags, bolsters, pads, literature as case reports.3,9,11,12,13 The precise incidence of air
pillows, or the mattress of the operating table. The careful po- embolism during spine surgery is unknown, complicated by the
sitioning of patients on operating support surfaces, and the varying sensitivity of detection methods.3 However it is known
use of support surfaces that minimize intra-abdominal pres- that the risk is dependent upon patient position and operative
sure, are recognized as essential in order to reduce the risks of site. In a review of pediatric patients undergoing neurosurgical
IVC obstruction.2,3,10 operations, there were two possible episodes of air embolism
in 120 operations, an incidence of 1.7%.14
Decreased Cardiac Index
Decreased cardiac index is a consistent physiological effect; an Edgcombe et al describe four case reports of fat embolism in
almost universal finding when a patient is moved from supine patients undergoing spine surgery in the prone position.3 In
to prone.3 The specific prone position used influences the ex- one case, involving lumbar decompression and spinal fusion
tent of hemodynamic effect. In one study of 21 patients under- with harvesting of the iliac crests for bone grafts, the authors
going lumbar surgery (1991), direct pulmonary artery and infe- considered that the prone position had contributed to the em-
rior vena cava (IVC) pressures were monitored: the flat prone bolic process, speculating that prolonged venous stasis had
position did not interfere with circulatory function, but use of played some part in the release of multiple emboli from bone
a convex saddle frame decreased the cardiac index and stroke harvesting sites.15
volume index, with no effect on IVC pressure.7 This was con-
firmed in a 2006 study, which used transesophageal echocar- Respiratory Effects
diography to compare different prone positioners.8 Cardiac As acknowledged by Edgcombe et al: “There are clear differ-
output decreased with the Wilson and Siemens AG frames, ences in respiratory physiology between the supine and prone
while cardiac index and stroke volume decreased with the An- position, including an increase in functional residual capacity
drews, Wilson, and Siemens systems. Cardiac preload decreased and alterations in the distribution of both ventilation and per-
using the Andrews frame. The Jackson spine table and longi- fusion throughout the lungs.”3 Provided that the patient is sup-
tudinal bolsters had the least effect on cardiac performance. ported with the abdomen free from pressure, prone positioning
These studies demonstrate that the prone position can have an is known to improve ventilation/perfusion matching and con-
important hemodynamic impact, which varies with the type of sequently improve oxygenation in the surgical patient.2,3
patient support used.
However, if abdominal compression occurs, this can lead to
In certain variants of the prone position, such as the Tuck posi- decreased respiratory compliance. Inadvertent compression
tion, venous drainage can be inadvertently obstructed by knee can happen if the patient is obese or incorrectly positioned on
or hip flexion, allowing pooling of blood in the dependent the operating frame. Under these circumstances, very high air-
structures and reduced atrial filling and cardiac output. Spinal way pressures may be required to ensure adequate ventilation.
surgery is often associated with unexpected blood loss and hy- High airway pressures can in turn impair venous return to the
povolaemia, which may itself cause cardiac arrest in susceptible heart, decreasing cardiac output and increasing systemic venous
patients. The prone position may exacerbate hypovolaemia by pressure. This in turn potentially affects spinal cord perfusion
further reducing venous return and cardiac output.9 pressure, increasing the patient’s risk for neurological complica-
tions.10 According to Martin and Warner: “The necessary high
Embolic Complications airway pressures and large tidal volumes needed to ventilate a
Air embolism is one of the most serious complications in spi- patient who is improperly positioned prone can have several
nal surgery. Any open vein in which there is subatmospheric potential side effects that can be harmful, (including): pulmo-
3 Copyright 2009, Allen Medical Systems. D-770490-A1 Oct. 22, 2009

4. nary interstitial emphysema leading to mediastinal, retroperito- to head rotation during anesthesia in the prone position.3 For
neal or subcutaneous emphysema; an exaggerated rise and fall these reasons, it is generally accepted that careful positioning of
of the patient’s back, potentially affecting the surgical field; and the neck, and head support in a neutral position are essential to
high venous and cerebrospinal fluid pressures, visible as fluid prevent neurological injury while prone.2,3,4
fluxes in the wound.” The authors recommend ensuring a posi-
tion that does not compress the abdomen and using the least Venous Occlusion
permissible lung inflation pressures to minimize venous conges- Edgcombe reports nine cases that involve prone patients and
tion and cerebrospinal fluid surges in the operative field.2 spinal surgery, in which hemodynamic changes have led to spi-
nal cord ischemia.3 In a study by Bhardwaj et al , four patients
Changes in pulmonary mechanics are also dependent on the developed new neurological deficits immediately after a cervical
type of prone position used, and on the equipment used to sup- laminectomy (two had hemiparesis, one quadriparesis, and one
port the patient prone. For example, Palmon (1998) showed that paraparesis).19 These patients were prone, supported by chest
pulmonary compliance decreased when patients were supported rolls. The authors proposed that the use of chest rolls led to in-
on chest rolls or on the Wilson frame, whereas the Jackson table creased venous pressure, which, when combined with mild arte-
was not associated with any change in pulmonary function.16 rial hypotension, decreased the perfusion pressure in the spinal
cord, causing ischemia. This paper states: “The use of frames
Summary that prevent abdominal compression, as well as avoidance of
Overall, it is evident that prone positioning of the patient, the perioperative arterial hypotension, is important in maintaining
type of patient support device used, and how the patient is adequate spinal perfusion during and after decompressive spinal
placed on the support can have a significant impact on cardiac cord surgery.” A similar mechanism is thought to explain an ad-
output, intra-abdominal venous pressure, respiratory compli- ditional case of quadriplegia after thoracolumbar decompres-
ance, extent of intra-operative blood loss and the risk of air or sion20 and two reports of thoracic level paraplegia after lumbar
fat embolism. spine surgery.21
Two cases occurred in patients with abnormal venous anatomy.
A patient with achondroplasia, who had stenosis of the jugular
2. CENTRAL NERVOUS SYSTEM foramina (a recognized feature of achondroplasia), developed
INJURY bilateral venous infarcts in the cerebellum. This occurred after
The manner in which the patient is positioned can result in seri- a nine hour thoracolumbar operation, head-down on a Wilson
ous injury to the central nervous system. Although an uncom- frame, with high intra-thoracic pressures during positive pres-
mon complication, central nervous system injury can occur sec- sure ventilation.22 Another case report describes a patient with
ondary to arterial or venous occlusion, air entrainment, cervical an occipital meningioma who was placed prone on a horseshoe
spine compression or from the triggering of symptoms related headrest: it is thought that the headrest caused compression of
to an undiagnosed space-occupying lesion.3,6 the anterior emissary veins, leading to venous stasis and rupture
into the frontal extradural space.23
Ischemic Cerebrovascular Events
Excessive movement of the patient’s neck during positioning Air Entrainment
can affect blood flow in the carotid and vertebral arteries. Wang Entrainment of air into the cranial cavity is common after neu-
et al describe a patient who had a fatal ischemic stroke after rosurgical procedures and occurs in any operative position.3 In
being positioned prone with the head rotated during spinal sur- one study, 16 of 28 patients (57%) undergoing posterior fossa
gery. This patient had an unrecognized carotid artery stenosis.17 or cervical spine procedures in the prone position experienced
Another patient was reported as having a dissection of the left pneumocephalus, although this was asymptomatic and did not
carotid artery, resulting in hemiparesis and aphasia, after spinal result in neurological deficit.24 Two cases of tension pneumo-
surgery.18 The dissection was thought to be related to extension cephalus have been reported, both in children undergoing in-
or rotation of the neck during positioning. tracranial surgery, placed prone.25,26
Occlusion or dissection of the vertebral arteries has been re- A single case report of air entrainment into the spinal canal
ported in at least four cases, linked to hypoperfusion secondary (pneumorrhachis) after posterior fossa exploration, resulting in
Copyright 2009, Allen Medical Systems. D-770490-A1 Oct. 22, 2009
4

5. quadriplegia, was thought to be related to the prone head-down
position.27 The patient’s position was thought to have contrib- 3. PRESSURE INJURIES
uted to the tracking of air through the foramen magnum into
the cervical region. Injuries can occur in the prone position as a result of the direct
application of pressure, or indirectly, as a result of compression
Spinal Cord Compression of the vascular supply or nerves (Table 2).
Prone positioning is known to be a high risk factor for patients
with pre-existing spinal cord dysfunction. Two case reports de- TABLE 2: Pressure Injuries Related To The Prone Position
scribe postoperative paraplegia due to cervical spine injury, at- Injury From Indirect
Injury From
tributed to neck positioning during prone spinal surgery.3 An Direct Pressure
Pressure On
Vascular Supply or Nerves
18 year old patient had an eight hour operation to remove a
Pressure ulcers Visceral ischemia: hepatic
cerebellar medulloblastoma, placed prone in the “Concorde”
ischemia, pancreatitis, acute
position with hyperextension of the neck: afterwards, he had Contact dermatitis mesenteric ischemia.
a complete and permanent C5/6 sensory and motor deficit.28 Compression of the pinna Avascular necrosis of the
It was postulated that the cervical cord was stretched in a nar- femoral head
Viscerostomy damage
row spinal canal, with an already-bulging C5/6 disc, resulting
Limb compartment syndromes
in ischemia. The other case involved a patient placed prone for Tracheal compression
and rhabdomyolysis
two hours with head turned to the left side and cushion support, Mediastinal compression
who developed a prolapsed intervertebral disc at C6/7.29 The Peripheral nerve injury
Breast injury
authors concluded, “Careful neck positioning (is) mandatory for
patients receiving surgery in the prone position”. Injury to the genitalia
Joint and bone pain,
Undiagnosed space-occupying lesions dislocation or fracture
Prone positioning can trigger neurological symptoms in patients Source: Compiled from Martin, Edgcombe, Sengupta and Herkowitz, AORN.2,3,4,6
with previously asymptomatic space-occupying lesions within
the spinal canal or cranium. This is rare, reported in four cases.3 Pressure on The Skin and Underlying Tissue
In each case, the proposed mechanism involved altered cerebro- Complications related to pressure on the skin and underlying
spinal fluid flow and epidural venous engorgement. One patient tissue have been reported in published articles as contact derma-
with neurofibromatosis had a neurofibroma in the posterior fos- titis and pressure ulcers. Experienced clinicians have described
sa fall anteriorly when positioned prone, compressing the me- other injuries related to prone positioning that are not presented
dulla and pons and leading to bradycardia and fatal neurogenic as case reports or in case series in published articles, in particu-
pulmonary edema.30 lar, compression of the pinna and viscerostomy damage.2
Summary Contact Dermatitis
Positioning of the patient is of crucial importance to avoid seri- Edgcombe reviewed two case reports that describe contact der-
ous or fatal neurological injury. The prone position can cause matitis in patients positioned prone during surgery. One patient
neurological deficits through: an increase in abdominal pressure had their head supported in a flexible polyurethane foam posi-
leading to a decrease in spinal cord perfusion; provision of the tioner that supports the face during surgery by molding around
“right” conditions for the introduction of air into the cranial the eyes, nose and mouth. The other case developed contact
cavity or spinal cord; and, by exacerbating a neck position that dermatitis in response to a monitor placed on the forehead. The
can occlude the arterial supply to the brain or compress the spi- skin reaction was thought to have been exacerbated by the prone
nal cord. Patient support devices that minimize abdominal com- position causing pressure against the electrode conductive gel.3
pression and maintain the neck and body in a neutral position
can help prevent these neurological complications. Compression of The Pinna
Martin points out that improper positioning can cause all or part
of the ear to be folded over. Pressure can result in cartilaginous
damage that is potentially disfiguring.2
5 Copyright 2009, Allen Medical Systems. D-770490-A1 Oct. 22, 2009

6. Viscerostomy Damage the patient can decrease the pressure-reducing effect of a mat-
Viscerocutaneous stomas can be compressed by prone supports, tress or overlay33, and the use of a warming blanket under the
resulting in leakage of contents and operative contamination. patient during surgery has been shown to increase risk of pres-
Compression of the stoma can also potentially lead to ischemia sure ulcers.38 Although there is a need for additional studies to
of the stoma margins and a need for surgical revision.2 compare the pressure-reducing effects of various commercially-
available support surfaces, it is clear that patient positioning, and
Pressure Ulcers the support device used, are important factors in the prevention
It is widely recognized that surgery itself is a risk factor for the of intraoperative pressure ulcers.
development of pressure ulcers because of prolonged immobil-
ity, unrelenting pressure on dependent parts of the body, and use This is emphasized in the guidelines provided by the AORN
of anesthetic agents. Therefore, all surgical patients are regarded and others4,31,33 which recommend: the tailoring of positioning
as being at risk of damage to skin integrity, regardless of their devices to the surgical position used, and to the body habitus of
body position during surgery. The incidence of intraoperatively- the individual patient; the requirement for firm and stable de-
acquired pressure ulcers has been reported in studies to range vices to minimize shearing; the use of support surfaces resistant
from 8.5% to as much as 45%.31, 32,33,34 Since pressure ulcers to moisture; and, the design of support equipment to distribute
that are initiated by surgery often do not appear until one to four pressure evenly, over a large surface area.
days after an operation, these can be mislabeled, for example as
a burn. This means that these are often not directly attributed There are few studies assessing the incidence of pressure ulcers
to the surgical procedure and therefore the incidence of intra- in patients positioned prone and no studies so far that evaluate
operative pressure ulcers may be under-reported.32,34 the efficacy (in terms of ulcer prevention), of different support
devices used for patients placed in the prone position. Despite
The elderly, and patients with co-morbidity (such as diabetes, the lack of specific data, it is evident that prone patients are
preoperative hypertension, respiratory disease or vascular dis- at risk of pressure ulcer development, related to the increased
ease), and sub-optimal nutritional status or small body size, are risk inherent in undergoing a surgical procedure, the prolonged
known to be at increased risk of developing an intra-operative nature of spinal surgery, and the vigorous manipulation often
pressure ulcer.31,33,34 Perioperative exposure of the skin to required in this type of surgery (increasing the likelihood of
wetness (such as preparation solutions) and shearing, tearing shearing forces). As stated by Aronovitch: “All surgical patients
or friction forces are recognized as contributory factors.4,31,33 undergoing prolonged procedures should be considered at risk
Duration of anesthesia has also been implicated as a risk factor for intraoperative ulceration.”35 Many authors advise close at-
for skin ischemia in some studies. Aronovitch (1999) surveyed tention in prone patients to pressure points at the forehead,
1128 patients undergoing a procedure of at least three hours’ chin, tip of the nose, ears, breasts, genitalia, anterior superior
duration and reported an incidence of 5.8% for surgery lasting iliac spines, knees and feet.2,4,6 Sengupta and Herkowitz point
three to four hours, increasing to 13.2% for surgical procedures out that pressure on the face is especially high during posterior
lasting over seven hours.35 However, as noted by Price et al, this surgery of the cervical spine and cranio-cervical junction, and
relationship between risk and duration of surgery has not been recommend that Mayfield tongs are used, to reduce the effect
a consistent finding.34 Hoshowsky and Schramm describe the of pressure on the face.6 Case reports in prone patients describe
“interactive effects of patient risk factors”, referring to the in- intraoperative pressure sores on the malar regions of the face,
creased risk from a combination of contributory factors.36 chin, eyelids, nose, tongue and iliac crests.3
How the patient is positioned, and the characteristics of the op- Pressure ulcers are associated with significant costs, summed up
erating room support device used can exacerbate these macerat- by Schultz: “Pressure ulcers, regardless of their origin, represent
ing or tearing forces, or increase pressure on bony areas, result- negative outcomes for patients, including pain, additional treat-
ing in damage to skin integrity.31,32,33,34 For example, the use ments, and surgery, longer hospital stays, disfigurement or scar-
of a standard operating mattress is known to increase capillary ring, increased morbidity, and increased costs.”33 Beckrich and
interface pressures over bony prominences beyond the capillary Aronovitch calculated that, each year, approximately 1.6 million
closing pressure, making ischemia more likely.35 Foam caused patients developed hospital-acquired pressure ulcers, at a cost
significantly more ulcers than a standard operating table in one of $2.2 to $3.6 billion (1998 figures).39 23% of these ulcers oc-
study.37 Layering of materials such as blankets or padding under curred in surgical patients undergoing procedures lasting more
6 Copyright 2009, Allen Medical Systems. D-770490-A1 Oct. 22, 2009

7. than three hours, representing up to 42% of costs of ulcers de- between the spine and sternum while positioned prone. In three
veloping in hospital and an annual direct cost of $750 million to of the four cases, the problem was exacerbated by an underly-
$925 million (1998 figures).39 ing connective tissue defect, either Marfan’s Syndrome,47,48 or
tracheomalacia.49
Since pressure ulcers are considered preventable (according to
the National Pressure Ulcer Advisory Panel Statement on Pres- Sternal or Mediastinal Compression
sure Ulcer Prevention, 1992), damage to skin integrity during Compression of the heart or great vessels has occurred in pa-
surgery is considered indicative of deficient quality of care.40 tients positioned prone during spinal surgery, in cases where
That skin integrity is a hallmark of quality nursing and a Quality there is an anatomical abnormality, such as scoliosis50 or pectus
of Care indicator is endorsed by many professional, federal and excavatum51,52, and after cardiac surgery.53,54 Alexianu et al de-
private health care organizations, such as the American Nursing scribed severe hypotension in a child with pectus excavatum,
Association41, the Agency for Health Care Policy and Research scoliosis and neurofibromatosis around the great vessels, when
(AHCPR)42, American Medical Directors Association43, the placed in a prone position on transverse bolsters for posterior
Joint Commission on Accreditation of Healthcare Organiza- spine surgery: sternal pressure was relieved when bolsters were
tions44 and the ECRI Institute.32 placed longitudinally.51
It is widely-recognized that intra-operatively-acquired pressure Pressure On The Vascular Supply
ulcers expose nurses, surgeons, anesthesiologists and institutions Indirect pressure effects on the vascular supply during prone
to significant litigation risk.32, 39, 45, 46 According to the ECRI In- surgery have been reported in the published literature as cases
stitute (2006): “The mere existence of a pressure ulcer is often involving ischemia of the liver and bowel, compartment syn-
viewed as physical evidence of medical negligence.”32 drome and rhabdomyolysis, and avascular necrosis of the
femoral head.
Summary
Prone patients are at risk from intra-operatively-acquired skin Visceral Ischemia
damage because of the effects of anesthesia and the prolonged Compression on the abdomen when prone under anesthesia can
nature and physical forces required in surgical procedures that result in ischemia of abdominal organs. Hepatic ischemia and
require prone positioning (such as spinal surgery). The conse- hepatic infarction have been described after prolonged surgery
quences of pressure effects on the skin, in terms of morbidity in the prone position.50,55,56 The authors of these case reports
and health care costs, are substantial. Intra-operative positioning attributed the cause to the patient’s position and the possibil-
and patient support surfaces that mitigate these pressure effects ity of hypo-perfusion and ischemia of intra-abdominal organs.
are important factors in the prevention of skin complications. Edgcombe suggests that this complication may be more com-
This is recognized by professional and federal organizations mon than is realized: at least five other cases have been identi-
such as the AORN and AHCPR, which call for active preven- fied in a recent investigation by the United Kingdom National
tive measures, including adequate patient support surfaces, in Patient Safety Agency.3 Mofredj et al describe a case of acute
published guidelines.4,42 mesenteric ischemia following spinal surgery: prone position
and hypotension were thought to have led to venous stasis and
mesenteric vein occlusion in a patient with an inherited hyper-
coagulable state.57 Prone positioning has also been proposed as
4. PRESSURE EFFECTS
a cause of pancreatitis after spondylolisthesis surgery.58
ON THE CHEST
Tracheal Compression Limb Compartment Syndrome
Pressure on the trachea can result in serious consequences, since and Rhabdomyolysis
airway problems are difficult to manage in the prone patient and Flexion of the hips and knees whilst prone can lead to isch-
can result in cardiac arrest secondary to hypoxaemia.9 Four cas- emia of the muscles in the lower limbs, especially if surgery is
es of tracheal compression have been reported during surgery prolonged. Rhabdomyolysis is caused by muscle ischemia and
in patients positioned prone.3 All of these patients had thoracic re-perfusion, and is characterized by dark urine, muscle pain and
scoliosis, which is thought to have reduced the anterior-posteri- generalized weakness. Severe hypoperfusion can lead to lacti-
or diameter of the chest, causing the trachea to be compressed cacidosis and sometimes hyperkalemia, and acute renal failure.
7 Copyright 2009, Allen Medical Systems. D-770490-A1 Oct. 22, 2009

8. There is evidence that the knee-chest and “Tuck” positions de- Pressure on breasts and genitalia
crease blood flow in the posterior tibial artery, increase intra- Positioning devices can compress the scrotum and penis, and
muscular pressure in the anterior compartment of the leg and straps and seats to hold the female body in the kneeling prone
release biochemical markers of muscle damage.3 In one study, position place pressure on the female perineum.2
15 patients undergoing surgery for spondylolisthesis in the knee-
chest position all showed a significant increase in plasma creatine The prone position may inadvertently damage breast tissue, re-
phosphokinase levels, and six patients also had myoglobinemia sulting in chest wall pain, breast tenderness or bleeding of the
and myoglobinuria.59 nipples. Longitudinal positioning frames or rolls can damage
breast tissue by direct compression.2 Prolonged pressure on
Eight cases of compartment syndrome have been reported in a breast implant has the potential to result in implant rupture.
patients undergoing spinal surgery in various prone positions Martin has also noted that extensive breast tissue can potentially
that involved flexion of the hips and knees.3 In six of these cas- threaten positioning, by forming an unstable and shifting plat-
es, surgery lasted longer than three hours. Six patients required form when the patient is placed prone.2
fasciotomy and three cases were complicated by acute renal fail-
ure, which was fatal for one patient. Pressure on peripheral nerves
Peripheral nerve injury is one of the most frequent causes of
Rhabdomyolysis in the absence of compartment syndrome has morbidity resulting from improper positioning intraoperative-
been identified in four cases.3 Three of the patients had been ly.6 In one study, neurological injury related to positioning was
placed prone in Jackson frames for prolonged spinal surgery. found in 72 out of 50000 general surgery operations (0.14%),
It was thought that muscle ischemia could have resulted either of which 38% were brachial plexus injuries.65 A review based on
from compression of the large vessels in the abdomen (exac- the American Society of Anesthesiologists closed claims data-
erbated by obesity), or from direct compression of the thigh base found an association between prone positioning and claims
muscles against the support device. for nerve injury,66 however, reliable data on the incidence of
peripheral nerve injury specifically in the prone position
Avascular necrosis of the femoral head is lacking.
Orpen et al describe three patients with pre-operative radio-
logical signs of osteoarthritis, who developed collapse of the Intra-operative injury to peripheral nerves occurs through
femoral head within two to eight weeks after decompression of stretching or compression of the nerve, or due to nerve isch-
spinal stenosis.60 These patients had been positioned prone on emia. This is usually associated with prolonged surgery, although
a Montreal mattress. The authors postulated that the combina- has been noted to occur in procedures lasting 45 minutes.67 Pa-
tion of deliberate hypotension and prone positioning led to in- tients with diseased nerves (diabetes, peripheral vascular disease,
traosseous venous congestion and ischemia of a compromised alcohol dependency, pre-existing neuropathy) and anatomical
femoral head, leading to avascular necrosis. abnormalities that change the pressure point distribution (such
as scoliosis) have an increased risk of intra-operative peripheral
Pressure on bone and joints nerve damage.3,68 Although there are other recognized causes
Martin, Ray, and Sengupta and Herkowitz express concern over of intra-operative nerve damage (i.e., retraction injury or brachi-
patients placed prone who have pre-existing joint or bone prob- al plexitis), there is no doubt that malpositioning of the patient
lems, such as arthritis, osteoporosis and stiff joints (as in anky- and external compression from table surfaces, table edges and
losing spondylitis), or total joint replacements.2,6,61 The process restraining straps are important causative factors.3,68
of placing such patients prone, or the application of prolonged
pressure on joints while prone can lead to joint or bone pain, or Upper limb nerve injury
bone fractures. Brachial plexus injury is reported by Sengupta and Herkowitz
as more common in the prone position than in the supine or
Sutterlin and Rechtine reported shoulder pain in one patient lateral position.6 At least four cases of brachial plexus injury,
supported prone during spinal surgery.62 Two case reports de- and other cases involving ulnar, axillary, musculocutaneous and
scribe shoulder dislocation occurring during in prone surgical radial nerve injury, have been summarized as published case re-
patients.63,64 ports, related to intra-operative prone positioning.3
8 Copyright 2009, Allen Medical Systems. D-770490-A1 Oct. 22, 2009

9. Lateral femoral cutaneous nerve injury Summary
Compression of the lateral femoral cutaneous nerve (meral- It is widely-acknowledged that positioning of the patient is an
gia paresthetica) is a common complication of the prone po- important causative factor in the occurrence of peripheral nerve
sition during spine surgery.65,69,70 Posts supporting the pelvis, damage, and that correct positioning, as well as the use of sup-
or pillows under the patient can compress the nerve at the exit port devices that minimize pressure effects, are key to the pre-
below the anterior superior iliac spine.69,71 The risk of nerve vention of these injuries. Although complete recovery can be
injury increases with higher Body Mass Index, longer surgical expected in the majority of cases, some patients do experience a
time and if the patient has a degenerative spinal disorder.70 In permanent loss of nerve function.
one prospective study, 23.8% of 252 patients on a Relton-Hall
frame developed evidence of meralgia paresthetica after poste-
rior spine surgery.70 Mirovsky and Neuwirth reported that mer- 5. OPHTHALMOLOGICAL
algia paresthetica affected 20% of patients after posterior spine COMPLICATIONS
surgery on a Relton-Hall frame: in six of 105 patients, the injury There is no doubt that eye complications are associated with the
was bilateral.71 prone position during anesthesia, and the use of head support
equipment.3,79 Compared with supine and lateral positioning,
This condition is usually associated with hypoesthesia in the an- there is a ten-fold increase in eye injury associated with surgery
terolateral aspect of the thigh, and occasionally burning pain, while prone.79 Ophthalmological complications related to prone
hypersensitivity and dysesthesia.69 Although symptoms usually positioning during surgery range from keratoconjunctival injury,
resolve within six months of surgery, meralgia paresthetica can such as corneal abrasion and chemosis, to irreversible blindness.
rarely be associated with severe pain and restriction of activity.72 The review paper by Edgcombe et al provides a recent sum-
In the study by Mirovsky and Neuwirth, in 89% of patients, mary of the available evidence on visual loss following surgery
symptoms resolved within three months of surgery, but two pa- in the prone position, concluding that: “Ophthalmic complica-
tients still had pain and hypoesthesia of the anterolateral thigh tions are well recognized in patients who have been prone under
one year after surgery.71 anesthesia, and can be devastating.”3 This is acknowledged by
organizations such as the AORN and the American Society of
Facial Nerve Injury Anesthesiologists: these organizations have published guidelines
Several case reports relating to nerve injury of the head and for the prevention of postoperative visual loss (POVL).80, 81 Pa-
neck have been described in Edgcombe’s review, all attributed by tients undergoing spinal surgery are known to have an elevated
the authors to nerve compression related to the prone position: risk: a study of cases registered with the Scoliosis Research Soci-
One case of injury to the lingual and buccal nerves during ety (1997) estimated that one eye complication occurs for every
lumbar laminectomy;73 100 spinal procedures.82
Three patients with supra-orbital nerve compression;74,75
One phrenic nerve injury in a diabetic patient, due to over- Corneal abrasion
extension or rotation of the neck;76
Corneal abrasion is a well-recognized, usually self-limiting, com-
Recurrent laryngeal nerve damage due to the compres-
plication of anesthesia, regardless of patient position during
sion of the vocal cord and recurrent laryngeal nerve by the
surgery, resulting from incomplete closure of the eye, drying
tracheal tube, and traction of the recurrent laryngeal nerve
of the eyes, foreign bodies or other unintended materials con-
by rotation of the neck.77
tacting the eye during surgery.2,79 Rarely, abrasion can cause a
corneal ulcer and partial or complete visual loss in the affected
Penile Nerve Injury
eye. Biswas et al found an incidence of 55% for conjunctival
Injury to the dorsal nerve of the penis is described in two pa-
abrasions in prone patients undergoing cranial or spinal surgery
tients positioned prone on a fracture table.78 Operative posi-
in the prone position.83 According to Stambough: “The prone
tioning compressed the dorsal nerve of the penis between the
position is particularly implicated (in corneal abrasion) because
pubic symphysis and the perineal post of the fracture table. As
direct or indirect eye pressure is more likely to occur.”79 The
a consequence, both patients experienced difficulty in obtaining
AORN also notes that there is an increased risk for corneal
complete erections, which appeared to be permanent.
abrasion when the patient is in the prone position.81
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10. Chemosis
Postoperative conjunctival edema (chemosis) is noted by Martin Support devices can also affect IOP. One study found intraoc-
to be more likely to occur: “when the head of the prone patient ular higher pressures for patients with heads placed in pillows,
is below the level of the atrium, or when the infusion volume compared with head stabilization with Mayfield pins, although
of crystalloids is large.”2 This adverse event may be asymp- the study sample was small. Direct external pressure on the
tomatic or lead to conjunctival or corneal infection. Chemo- globes and periorbital structures, caused by a headrest or other
sis is a common postoperative finding in patients undergoing support, is known to increase intraocular pressure, potentially
lumbar spine surgery in the prone position. Jeon et al reported resulting in central retinal artery occlusion and POVL (de-
an incidence of moderate and severe chemosis at 6% and 4%, scribed as the “Hollenhorst Syndrome”).3 Ironically, devices
respectively, for patients positioned prone in a Wilson frame used to protect the eye can exert inadvertent pressure on the
during spinal surgery, with their head in a neutral position.84 In eye. Roth et al reported irreversible POVL in a 53 year old man
the head-down position, the incidence of moderate and severe secondary to use of protective goggles whilst in a prone posi-
chemosis increased to 31% and 7%, respectively. Positive fluid tion during spinal surgery.95 The authors of this study searched
balance and duration of surgery increased the risk. the Medwatch MAUDE database and found additional cases
of patient injury from use of the goggles, all in patients placed
Postoperative visual loss prone in a foam headrest (including keloid scarring on the
It is known that postoperative visual loss (POVL) is associated nose, skin abrasions, eyelid abrasions and neuropraxia of the
with spinal surgery and with prone positioning, although the supraorbital nerve).
pathophysiology, etiology, incidence, risk factors and preven-
tion of POVL are still being characterized. Stambough and Ischemic optic neuropathy
Edgcombe provide informative reviews of the latest research An increase in intraocular pressure or venous pressure, or a de-
on POVL and the association of POVL with prone positioning crease in arterial pressure can diminish oxygenation of the op-
and spinal surgery.3,79 Buono and Foroozan (2005) compre- tic nerve, leading to ischemic optic neuropathy (ION).3 ION
hensively describe the research on ischemic optic neuropathy can occur in the absence of external pressure from headrests,
and the relationship of this condition to spinal surgery.86 when the head is supported in pins, for example. As stated by
Edgcombe, “A variety of factors influence intraocular pressure
67% of all cases of post-operative visual loss registered on and some of these are clearly altered by prone positioning.”
the American Society of Anesthesiologists Postoperative Vi- Prone positioning and spinal surgery potentially raise intraocu-
sual Loss Registry occurred after prone surgery.85 A retrospec- lar pressure by: 1) increasing venous pressure and peak inspira-
tive review of 3450 spinal operations in 1997 found that 0.2% tory pressure, thereby increasing intraocular pressure79; 2) in-
of patients developed visual loss after spinal surgery.90 The creasing the risk of abdominal compression, reducing cardiac
incidence of visual loss after spinal surgery in the prone po- output and mean arterial pressure; 3) the use of a deliberate
sition at one institution91 was 1 in 1100, compared with the anesthetic technique that reduces arterial pressure to minimize
incidence in the general surgical population of 1 in 61000.92 In blood loss. Other factors apart from hypotension that increase
the prone, anesthetized patient, central retinal artery occlusion the risk of ION following spinal surgery include blood loss of
and ischemic optic neuropathy are the most common reasons 1000ml or greater, anesthetic duration of six hours or longer,
for POVL.3 complex instrumentation during scoliosis surgery, administra-
tion of large volumes of clear fluids, and pre-existing hyper-
Central retinal artery occlusion tension or vascular disease (such as atherosclerosis and dia-
Factors that increase intraocular pressure can lead to central betes).79,85 Buono and Foroozan describe the well-recognized
retinal artery occlusion, retinal ischemia and POVL. The prone phenomenon that a head-down and prone position can result
position itself has been associated with raised intraocular pres- in increased venous pressure, with facial and orbital edema,
sure (IOP).93,94 Cheng et al measured IOP in 20 patients sched- especially after prolonged surgery and large volumes of intra-
uled for spine surgery in the prone position. IOP was noted to operative fluid replacement.86
increase in prone patients, and during anesthesia.93 Hunt con-
firmed these results in patients undergoing spinal surgery and Occipital cortical infarct
concluded that: “IOP increases when anesthetized patients are Cortical blindness is caused by an isolated stroke that selec-
placed in the prone position.”94 tively affects the visual cortex.79 Hypo-perfusion or embolism
10 Copyright 2009, Allen Medical Systems. D-770490-A1 Oct. 22, 2009

11. are the underlying factors, leading to occipital cortical infarct or cortical blindness. Stambough discusses this complication in his
review article: Ophthalmic Complications Associated with Prone Positioning in Spine Surgery (2007).79
Other causes of visual loss
Case reports have been published describing other visual complications after surgery in the prone position. These cases include:
supraorbital neuropraxia (three patients), transient or permanent ophthalmoplegia (nine patients), and single case reports of cav-
ernous sinus thrombosis, central retinal vein occlusion, orbital hemangioma, orbital compartment syndrome, bilateral angle closure
glaucoma, non-traumatic subperiosteal orbital hemorrhage, amaurosis, dislocated intraocular lens; and fixed mydriasis.3,79 Some of
these cases are described below:
CASE EXAMPLE: A 76 year-old patient had surgery for cervical spine stenosis, five hours’ prone un-
der anesthesia, with head supported on a Mayfield head clamp. On awakening, he reported unilateral
visual loss. On examination, he had mild left proptosis with lid swelling and conjunctival chemosis.
Pupil was mid-dilated and non-reactive. Fundoscopy showed retinal edema with a cherry-red foveal
spot. A cerebral angiogram two weeks later showed a left cavernous sinus thrombosis. The authors
attributed this complication, which resulted in irreversible long-term visual loss, to pressure from the
headrest. Anand and Mushin, 2004.87
CASE EXAMPLE: An 80-year old man underwent an eight hour lumbar laminectomy for lumbar
spinal stenosis. A silicone head rest was used. The patient experienced facial edema, corneal edema
with an extensive corneal abrasion, a nonreactive pupil, advanced cataract and complete ophthal-
moplegia, leading to complete and irreversible visual loss in the eye. The authors suggested that:
“The progressive orbital edema secondary to the prone position, and possible unilateral direct pres-
sure from the headrest device on periorbital structures resulted in congestion at the orbital apex, with
a subsequent compartment syndrome and ischemic orbit.” Leibovitch et al, 2005.88
CASE EXAMPLE: A 16 year old girl had scoliosis surgery in the prone position, her face resting on
a padded, gel-filled horseshoe rest and eyes taped shut and padded with gauze. After surgery, she
complained of visual loss in the right eye. Computed tomography showed a swollen medial rectus
muscle with no other orbital pathology. The authors attributed the permanent visual loss to ocular
compression against the headrest, caused by repositioning of the patient during surgery. Kumar et al,
2004.89
Summary
Ophthalmological complications related to prone positioning range from common, self-limiting and mildly symptomatic corneal
abrasions or chemosis, to rare, permanent and potentially devastating visual loss. Prone positioning on head support devices plays an
important part in the causation and prevention of all of these ophthalmological complications.
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12. Humphreys et al described complications in a series of 107 pe-
6. OROPHARYNGEAL
diatric patients undergoing upper cervical spine and posterior
COMPLICATIONS
cranial fossa surgery in the prone position.99 A Relton frame
Hans et al describe a case of bilateral painful swelling of the with Mayfield or Gardner head holder was used. The authors
submandibular glands occurring after neurosurgery in the reported the following as complications related to the position-
prone position, with the patient’s head supported in a Mayfield ing of the patient: a drop in temperature (in all 24 infants, and
holder.96 The authors determined that stretching of the salivary reduction of greater than 3oC in three of these patients), ob-
ducts, leading to stasis and acute swelling, explained the underly- structed endotracheal tube, possible air embolus (two patients)
ing etiology. Another paper describes six cases of bilateral pa- and blood loss. However, the authors concluded that the prone
rotid gland enlargement occurring after general anesthesia (“an- position was safer than supine and sitting positions for pediatric
esthesia mumps”), five of which occurred after prone surgery.97 patients who needed this kind of surgical treatment, since the
Vascular congestion resulting from the patient’s position during risk of air embolism was less.
surgery was thought to have contributed to this complication.
TABLE 3: Pediatric complications of the prone position
Three reports document macroglossia after surgery in the prone Pediatric Complications
position, complicating a suboccipital craniotomy, a posterior Unintentional extubation
cervical spine decompression and posterior fossa surgery.3 The
Eye complications: corneal abrasions, conjunctival and perior-
authors identified obstruction to venous drainage, excessive bital edema of the dependent eye, retinal ischemia, post-oper-
flexion of the head, and/or the tracheal tube obstructing venous ative visual loss due to ischemic optic neuropathy.
drainage from the lingual and pharyngeal veins as underlying Entangling of cables.
mechanisms.
Abdominal compression (leading to impaired ventilation, in-
creased bleeding, and decreased cardiac output).
Improper head and neck positioning (leading to venous and
lymphatic obstruction).
7. COMPLICATIONS OF THE PRONE
POSITION IN PEDIATRIC PATIENTS Macroglossia.
In children, complications linked to prone positioning are similar Possibility of venous air embolism.
to those described for adults. However, there are particular risks Source: Soundararajan and Cunliffe98
in children related to: the hemodynamic consequences of posi-
tioning, blood loss, and the potential for vascular compromise Being positioned prone on a support involving four pillars, such
of the spinal cord; underlying pathology (such as spinal defor- as the Relton-Hall table, increases the potential for heat loss in
mity, or genetic syndromes with “hidden” organ structure, dys- children, since the ventral surface of the patient is exposed to
function or location); and, age-related anesthetic considerations, room air. LeBard100 and Soundararajan98 point out that hypo-
particularly hypothermia in neonates and small children.98,99 thermia prolongs recovery from neuromuscular block, impairs
These complications are summarized in Table 3. Soundararajan platelet function, and leads to a higher incidence of wound in-
and Cunliffe describe these challenges in their paper, Anesthesia fections.
for Spinal Surgery in Children (2007).98 The authors emphasize
the importance of: “Careful positioning of the patient to pre- Meralgia paresthetica has also been noted after posterior spine
vent compression of the abdomen,” especially with the aim of fusion in pediatric patients Tejwani et al found that, of 56 chil-
minimizing both spinal cord ischemia and compression on the dren undergoing spine fusion for scoliosis (on a Jackson table
spinal cord, whilst maintaining a bloodless surgical field. They with either the lower leg support table and thigh supports, or
also caution that: “Anesthetic management requires a meticu- lower leg suspension sling), 10 (18%) developed meralgia par-
lous approach to safety, positioning, and spinal cord perfusion, esthetica.101 This manifested as anterolateral thigh numbness
with maintenance of normothermia and normovolemia.” without pain or weakness. Symptoms in all affected patients re-
solved in less than 6 weeks. Patients with meralgia paresthetica
Meridy et al reviewed pediatric patients undergoing neurosurgi- more often had idiopathic scoliosis, were positioned with the
cal operations and reported two possible episodes of air embo- lower leg sling instead of the flat table support and tended to
lism in 120 operations, an incidence of 1.7%.14 have longer surgery times.
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13. SUMMARY
The most common complications associated with the prone position include: ischemia of the skin at pressure points, peripheral
nerve compression, and mild ocular injuries. These surgical outcomes can lead to prolonged hospital stays and increased health
care costs, and have a significant impact on the patient’s recovery time and quality of life. Many additional complications of prone
positioning occur less frequently, but can have serious consequences for the patient, leading to pain, disability, paralysis, visual loss,
or even death.
Complications of prone positioning during anesthesia are related to the following factors, or to a combination of these factors:
the physiological effects of being prone;
the consequences of compression on the abdomen while prone;
the nature of spinal surgery (such as prolonged duration, the need for a clear surgical field, manipulation and
movement of the patient to allow instrumentation);
pressure effects on different parts of the body from the equipment used to support the prone patient.
The evidence presented in this summary illustrates the importance of the equipment used to support the patient. The review by
Edgcombe et al concluded: “It is clear that the specific prone position and support system used influences not only the incidence
of complications but also the alterations in cardiovascular and respiratory physiology which occur when a patient is moved from a
supine to prone position in the operating theater.”3 The way in which the patient is supported whilst prone influences the occurrence
and severity of complications. The design of support equipment to minimize these complications, together with appropriate educa-
tion of staff in how to optimize the preventive qualities of support devices, is vitally important. There is also a need for research that
provides an evidence base demonstrating the efficacy and safety of different types of operating room support equipment.
13 Copyright 2009, Allen Medical Systems. D-770490-A1 Oct. 22, 2009

14. REFERENCES
1
Singh I. The Prone Position: Surgical Aspects. In: Martin JT, ed. Positioning in Anesthesia and Surgery. Chapter 16. Philadelphia:
Saunders, 1987.
2
Martin JT. The Ventral Decubitus (Prone) Position. In: Martin JT and Warner MA, eds. Positioning in Anesthesia and Surgery.
Chapter 10. Philadelphia: Saunders, 1997.
3
Edgcombe H, Carter K, Yarrow S. Anaesthesia in the prone position. Br J Anaesth 2008; 100: 165-83
4
AORN Recommended Practices Committee. Recommended Practices for Positioning the Patient in the Perioperative Practice
Setting. AORN Journal. 2001:73(1);231-238.
5
Zileli M, Naderi S, Benzel EC. Preoperative and Surgical Planning for Avoiding Complications. In: Benzel EC, ed. Spine Surgery:
Techniques, Complication Avoidance and Management. Philadelphia: Elsevier Churchill Livingstone, 2005.
6
Sengupta DK, Herkowitz HN. Complications of Anesthesia Administration and Positioning for Spinal Surgery. In: Vaccaro AR, ed.
Complications of Pediatric and Adult Spinal Surgery. Chapter 2. New York: Marcel Dekker, 2004.
7
Yokoyama M, Ueba W, Hirakawa M, Yamamoto H. Hemodynamic effect of the prone position during anesthesia. 1991.Acta An-
aesthesiol Scand;35:741-4.
8
Dharmavaram S. Jellish WS. Nockels RP. Shea J. Mehmood R. Ghanayem A. Kleinman B. Jacobs W. Effect of prone position-
ing systems on hemodynamic and cardiac function during lumbar spine surgery: an echocardiographic study. Spine. 2006; 31(12):
1388-94.
9
Brown J, Rogers J, Soar J. Cardiac arrest during surgery and ventilation in the prone position: a case report and systematic review.
Resuscitation. 2001; 50(2): 233-8.
10
Schonauer C, Bochetti A, Barbagallo G, Albanese V, Moraci A. Positioning on surgical table. Eur Spine J. 2004; 13(Suppl 1): 850-
855.
11
Wills J, Schwend RM, Paterson A, Albin MS. Intraoperative visible bubbling of air may be the first sign of venous air embolism
during posterior surgery for scoliosis. Spine. 2005;30(20): E629-635.
12
Albin MS, carroll Rg, Maroon JC. Clinical considerations concerning detection of venous air embolism. Neurosurgery. 1978; 3:
380-4.
13
Albin MS, Ritter RR, Pruett CE, Kaliff K. Venous air embolism during lumbar laminectomy in the prone position: report of three
cases. Anesth Analg 1991; 73: 346-9.
14
Meridy HW, Creighton RE, Humphreys RP. Complications during neurosurgery in the prone position in children. Can Anesth Soc
J. 1974; 21: 445-53.
15
Brandt SE, Zeegers WS, Ceelen TL. Fatal pulmonary fat embolism after dorsal spinal fusion. Eur Spine J. 1998; 7:426-8.
16
Palmon SC, Kirsch JR, Depper JA, Toung TJ. Anesthesia & Analgesia. 1998; 87(5): 1175-80.
17
Wang LC. Liou JT. Liu FC. Hsu JC. Lui PW. Fatal ischemia stroke in a patient with an asymptomatic carotid artery occlusion after
lumbar spine surgery-a case report. Acta Anaesthesiologica Taiwanica. 2004; 42(3): 179-82.
18
Gould DB, Cunningham K. Internal carotid artery dissection after remote surgery. Iatrogenic complications of anesthesia. Stroke
1994; 25: 1276-8.
19
Bhardwaj A. Long DM. Ducker TB. Toung TJ. Neurologic deficits after cervical laminectomy in the prone position. J Neurosurg
Anesthesiol. 2001;13(4):314-9.
20
Deem S, Shapiro HM, Marshall LF. Quadriplegia in a patient with cervical spondylosis after thoracolumbar surgery in the prone
position. Anesthesiology. 1991:75(3);527-8.
21
Turker RJ. Slack C. Regan Q. Thoracic paraplegia after lumbar spinal surgery. Journal of Spinal Disorders. 1995;8(3):195-200.
22
Elmaci I, Ain MC, Wright MJ. Perioperative intracranial hemorrhage in achondroplasia: a case report. J Neurosurg Anesthe-
siol.2000; 12: 217-20.
23
Chandra Ps, Jaiswal A, Mahapatra AK. Bifrontal epidural haematomas following surgery for occipital falcine meningioma: an un-
usual complication of surgery in the prone position. J Clin Neurosci.2002;9:582-4.
24
Toung et al. Pneumocephalus: effects of patient position on the incidence and location of aerocele after posterior fossa and upper
cervical cord surgery. Anesthesia. 1986;65(1):65-70.
25
Olympio MA, Bell WO. Venous air embolism after craniotomy closure: tension pneumocephalus implicated. J Neurosurg Anes-
thesiol.1994;6(1):35-9
26
Wronski M, Ferber J, Wronski J. Acute tension pmeumocephalus as a complication of operation on the posterior cranial fossa in
prone position.1987;21(2):167-70.
27
Prabhakar H. Bithal PK. Ghosh I. Dash HH. Pneumorrhachis presenting as quadriplegia following surgery in the prone position.
14 Copyright 2009, Allen Medical Systems. D-770490-A1 Oct. 22, 2009

15. British Journal of Anaesthesia. 2006; 97(6): 901-3.
28
Rau CS, Liang CL, Lui CC, Lee TC, Lu K. Quadriplegia in a patient who underwent posterior fossa surgery in the prone position.
Journal of Neurosurgery. 2002; 96(1Suppl):101-3.
29
Chen S, Hui Y, Yu, C, Niu C, Lui P. Paraplegia by acute cervical disc protrusion after lumbar spine surgery. Chang gung Med
J.2005; 28(4): 254-6.
30
Van Aken H, Scherer R, Lawin P. A rare intra-operative complication in a child with Von Recklinghausen’s neurofibromatosis.
Anaesthesia. 1982; 37: 827-9.
31
Armstrong D, Bortz P. An integrative review of pressure relief in surgical patients. AORN J. 2001; 73(3): 645-669.
32
Healthcare Risk Control System of ECRI. Executive summary: Pressure Ulcers. Nursing. 2006; 4(3):1-20.
33
Schultz A. Predicting and preventing pressure ulcers in surgical patients. AORN J. 2005;81:986-1006.
34
Price MC, Whitney JD, King CA, Doughty D. Development of a risk assessment tool for intraoperative pressure ulcers. J Wound
Ostomy Continence Nurs. 2005; 32(1):19-30.
35
Aronovitch SA. Intraoperatively acquired pressure ulcer prevalence: a national study. J Wound Ostomy Continence Nurs.
1999;26(3):130-136.
36
Hoshowsky VM, Schramm CA. Intraoperative pressure sore prevention: an analysis of bedding materials. Res Nurs Health. 1994
Oct;17(5):333-9.
37
Schultz A, Bien J, Dumond K, et al. Etiology and incidence of pressure ulcers in surgical patients. AORN J. 1999;70(3):434-447.
38
Grous C, Reilly N, Gift A. Skin integrity in patients undergoing prolonged operations. J Wound Ostomy Continence Nurs. 1997;
24: 86-91.
39
Beckrich K, Aronovitch SA. Hospital-acquired pressure ulcers; a comparison of costs in medical versus surgical patients. Nursing
Economics.1999;17(5):263-271.
40
National Pressure Ulcer Advisory Panel Statement on Pressure Ulcer Prevention, 1992. www.npuap.org/positn1.htm
41
American Nurses Association nursingworld.org/.../NDNQI/Research/QIforAcuteCareSettings.aspx
42
Treatment of pressure ulcers. AHCPR. Pressure ulcers and adults: prediction and prevention. Clinical Practice Guideline No 3,
AHCPR Pub No. 92-0047, 1992.
43
American Medical Directors Association. Clinical Practice Guideline for Pressure Ulcers For Medical Directors and Attending
Physicians. CPG2-12, revised 2008. www.amda.com/tools/cpg/pressureulcer.cfm
44
Joint Commission on Accreditation of Healthcare Organizations. National Patient Safety Goals, 2008. http://www.jcrinc/fpdf/pubs/
pdfs/JCP-07-07-S1.pdf
45
Bliss M, Simini B. When are the seeds of postoperative ulcers sown? Often during surgery. BMJ. 1999; 319(7214): 863-864.
46
Akhtar N. Thompson WR. Weiler-Mithoff EM. Patient positioning on the operating table: a priority in surgical training? Annals of
the Royal College of Surgeons of England. 2005; 87(3):209-10.
47
Kai Y, Yamaoka A, Irita K, Zaitsu A, Takahashi S. Transient tracheal obstruction during surgical correction of scoliosis in a patient
with Marfan’s syndrome. Masui. 1995; 44: 868-73.
48
Mesrobian RB, Epps JL. Midtracheal onstruction after Harrington rod placement in a patients with Marfan’s syndrome. Anesth
Analg. 1986; 65:411-3.
49
Rittoo DB, Morris P. Tracheal occlusion in the prone position in an intubated patient with Duchenne muscular dystrophy. Anaes-
thesia. 1995; 50: 719-21.
50
Yuen VMY, Chow BFM, Irwin MG. Severe hypotension and hepatic dysfunction in a patient undergoing scoliosis surgery in the
prone position. Anaesth Intensive Care. 2005; 33: 393-9.
51
Alexianu D, Skolnick ET, Pinto AC. Sever hypotension in the prone position in a child with neurofibromatosis, scoliosis and pectus
excavatum presenting for posterior spinal fusion. Anesth Analg. 2004; 98: 334-5.
52
Teoh DC, Williams DL. Adult Klippel-Feil syndrome: haemodynamic instability in the prone position and postoperative respiratory
failure. Anaesthesia & Intensive Care. 2007;35(1):124-7.
53
Hiraga Y, Maruoka H, Yamamoto M, Hama T, Kurioka M, Inamori K, Hyodo M. Compression of the graft during the corrective
surgery for scoliosis in a patient who has undergone a Rastelli’s operation: a case study. Japanese Journal of Anesthesiology.
1992;41(9):1490-3.
54
Weinlander CM, Coombs DW, Plume SK. Myocardial ischemia due to obstruction of an aortocoronary bypass graft by intraopera-
tive positioning. Anesth Analg. 1985;64(9):933-6.
55
Ziser A, Friedhoff RJ, Rose SH. Prone position: visceral hypoperfusion and rhabdomyolysis. Anesth Analg. 1996; 82: 412-5.
56
Satomoto M. Takagi Y. Igarashi H. Sato S. Hepatic infarction following prolonged prone position. Masui. 2006; 55(9):1170-2.
57
Mofredj A. Traore I. Beldjoudi B. Aoula D. Douiri R. Acute bowel ischemia following spinal surgery. Southern Medical Journal.
15 Copyright 2009, Allen Medical Systems. D-770490-A1 Oct. 22, 2009

16. 2006; 99(5): 528-30.
58
Curtin WA, Lahoti OP, Fogarty EE, Dowling FE, Regan BF, Drumm B. Pancreatitis after alar-transverse fusion for spondylolisthe-
sis. A case report. Clinical Orthopaedics & Related Research. 1993; 292: 142-3.
59
Davidas JL, Roullit S, Dubost J. Creatine phosphokinases and serum and urinary myoglobin following a procedure in prolonged
knee-chest position for the treatment of spondylolisthesis. Ann Fr Anesth Reanim. 1986; 5: 31-4
60
Orpen N. Walker G. Fairlie N. Coghill S. Birch N. Avascular necrosis of the femoral head after surgery for lumbar spinal stenosis.
Spine. 2003; 28(18):E364-7.
61
Ray CD. New kneeling attachment and cushioned face rest for spinal surgery. Neurosurgery. 1987; 20(2): 266-9.
62
Sutterlin C, Rechtine GR. Using the Heffington frame in elective lumbar spinal surgery. Orthopaedic Review. 1988; 17(6): 597-
600.
63
Hinton AE, King D. Anterior shoulder dislocation as a complication of surgery for burns. Burns.1989; 15(4): 248-9.
64
Ali AA. Breslin DS. Hardman HD. Martin G. Unusual presentation and complication of the prone position for spinal surgery. Journal
of Clinical Anesthesia. 2003; 15(6): 471-3.
65
Parks BJ. Postoperative peripheral neuropathies. Surgery. 1973;74(3):348-57.
66
Kroll DA, Caplan RA, Posner K, Ward RJ, Cheney FW. Nerve injury associated with anesthesia. Anesthesiology. 1990; 73: 202-
7
67
Dhuner KG. Nerve injuries following operations: a survey of cases occurring during a six-year period. Anesthesiology. 1948; 11:
289.
68
Winfree CJ, Kline DG. Intraoperative positioning nerve injuries. Surgical Neurology. 2005; 63(1): 5-18.
69
Peker S, Ay B, Sun I, Ozgen S, Pamir MN. Meralgia paresthetica: complication of prone position during lumbar disc surgery. The
Internet Journal of Anesthesiology.2004; 8(1).
70
Yang S, Wu CC, Chen PQ. Postoperative meralgia paresthetica after posterior spine surgery: incidence, risk factors, and clinical
outcomes. Spine. 2005; 30(15): E547-50.
71
Mirovsky Y. Neuwirth M. Injuries to the lateral femoral cutaneous nerve during spine surgery. Spine. 2000; 25(10):1266-9.
72
Ratcliff JK, Jacques L, Tiel R. MP following iliac crest bone graft for anterior cervical discectomy: a case report and review of the
literature. http://www.medschool.lsuhsc.edu/Neurosurgery/nervecenter/mp.html (Accessed March 2008)
73
Winter R, Munro. Lingual and buccal nerve neuropathy in a patient in the prone positiong: a case report. Anesthesiology
1989;71:452-4.
74
Wolfe SW, Lospinuso MP, Burke SW. Unilateral blindness as a complication of patient positioning for spinal surgery. A case report.
Spine.1992;17:600-5.
75
Hollenhorst R, Svien HJ, Benoit CF. Unilateral blindness occurring during anesthesia for neurosurgical operations. AMA Arch
Ophthalmol 1954; 52: 816-30.
76
Wakeno M, Sakamoto S, Asai T, Hirose T, Shingu K. a case of diaphragmatic paralysis in a patient with diabetes mellitus after
surgery in prolonged prone position. Masui.2001;50:1019-21.
77
Ono S, Nishiyama T, Hanaoka K. Hoarseness after endotracheal intubation casued by submucosal hemorrhage of the vocal cord
and recussrent nerve palsy. Masui 2000; 49: 881-3.
78
Hofmann A, Jones RE, Schoenvogel R. Pudendal-nerve neurapraxia as a result of traction on the fracture table. A report of four
cases. Journal of Bone & Joint Surgery - American Volume. 1982;64(1):136-8.
79
Stambough JL, Dolan D, Werner R, Godfrey E. Ophthalmic Complications Associated with Prone Positioning in Spine Surgery. J
Am Acad Orthop Surg. 2007;15:156-165.
80
American Society of Anesthesiologists: Practice Advisory for Perioperative Visual Loss Associated with Spinal Surgery. Anesthe-
siology.2006;104:1319-28.
81
Recommended Practices for Positioning the Patient in the Perioperative Practice Setting. Recommendation VIIIi. aorn.org/docs_
assets/.../05RP_Positioning_11-6-07_pub_rev.pdf
82
Myers MA, Hamilton SR, Bogosian AJ, Smith CH, Wagner TA. Visual loss as a complication of spine surgery. A review of 37 cases.
Spine. 1997 Jun 15;22(12):1325-9.
83
Biswas BK, Bithal PK, Dash M. Keratoconjunctival injury in the prone position: a prospective study in neurosurgical patients. Eur
J Anaesthesiol. 2004; 21: 663-665.
84
Jeon YT. Park YO. Won Hwang J. Lim YJ. Oh YS. Park HP. Effect of head position on postoperative chemosis after prone spinal
surgery. J Neurosurg Anesthesiol.2007;19(1):1-4.
85
Lee L. ASA Postoperative visual loss registry: preliminary analysis of factors associated with spine operations. ASA Newsletter.
2003; 67:7-8.
16 Copyright 2009, Allen Medical Systems. D-770490-A1 Oct. 22, 2009

17. 86
Buono LM, Foroozan R. Perioperative ischemic optic neuropathy: review of the literature. Surv Ophthal. 2005; 50(1): 15-26.
87
Anand S, Mushin AS Cavernous sinus thrombosis following prone position anaesthesia. Eye. 2005; 19: 803-4.
88
Leibovitch I, Casson R, Laforest C, Selva D. Ischemic orbital compartment syndrome as a complication of spinal surgery in the
prone position. Ophthalmol. 2006; 113:105-8
89
Kumar N, Jivan S, Topping N, Morrell J. Blindness and rectus muscle damage following spinal surgery. Am J Ophthalmol. 2004;
138(5): 889-891.
90
Stevens WR, Glazer PA, Kelley SD, Lietman TM, Bradford DS. Ophthalmic complications after spinal surgery. Spine.1997;
22:1319-24.
91
Roth S, Barach P. Postoperative visual loss: still no answers-yet. Anesthesiology. 2001;95(3):575-7.
92
Roth S, Thisted RA, Erickson JP, Black S, Schreider BD. Eye injuries after nonocular surgery: A study of 60,965 anesthetics from
1988–1992. Anesthesiology. 1996;85:1020–7
93
Cheng MA, Todorov A. Tempelhoff R, MHugh T, Crowder CM, Lauryssen C. The effect of prone positioning on intraocular pressure
in anesthetized patients. Anesthesiology. 2001; 95: 1351-5.
94
Hunt K, Bajekal R, Calder I, Meacher R, Eliahoo, Acheson JF. Changes in intraocular pressure in anesthetized prone patients. J
Neurosurg Anesthesiol. 2004; 16(4): 287-290.
95
Roth S, Tung A, Ksaizek S. Visual loss in a prone-positioned spine surgery patient with the head on a foam headrest and goggles
covering the eyes: an old complication with a new mechanism. Anesth analg 2007; 104: 1185-7.
96
Hans P. Demoitie J. Collignon L. Bex V. Bonhomme V. Acute bilateral submandibular swelling following surgery in prone position.
European Journal of Anaesthesiology. 2006; 23(1): 83-4.
97
Kimura H, Watanabe Y, Mizukoshi K, Yamamoto Y, Araki S. Six cases of anesthesia mumps. Journal of the Oto-Rhino-Laryngo-
logical Society of Japan. 1993; 96(11): 1915-21.
98
Soundararajan N, Cunliffe M. Anaesthesia for spinal surgery in children. British Journal of Anaesthesia. 2007; 99(1): 86-94.
99
Humphreys RP, Creighton RE, Hendrick EB, Hoffman HJ. Advantages of the prone position for neurosurgical procedures on the
upper cervical spine and posterior cranial fossa in children. Child’s Brain. 1975; 1(6):325-36.
100
LeBard SE. Pediatrics. In: Martin JT, ed. Positioning in Anesthesia and Surgery. Chapter 15. Philadelphia: Saunders, 1997.
101
Tejwani SG, Scaduto AA, Bowen RE. Transient Meralgia paresthetica after pediatric posterior spinal fusion. J Pediatr Orthop.
2006; 26: 530-533.
17 Copyright 2009, Allen Medical Systems. D-770490-A1 Oct. 22, 2009