Current Issues In Emergency Medicine - A Selected Update

Selected Current Issues In
Emergency Medicine
K.S. Chew
School of Medical Sciences
Universiti Sains Malaysia

Sensitivity, Specificity, PPV and NPV
Disease POSITIVE Disease NEGATIVE
Test POSITIVE A (True POSITIVE) B (False POSITIVE)
Test NEGATIVE C (False NEGATIVE) D (True NEGATIVE)
A + C B + D
Sensitivity: The probability of the test able to detect the disease
among the population WITH the disease
Sensitivity = A/ (A+C)
Specificity: The probability of the test NOT detecting the
disease among the population who DO NOT have the disease
Specificity = D/(B+D)

A + C B + D
Positive Predictive Value (PPV): The percentage of people with
a positive test result who actually have the disease.
PPV = A/(A+B)
Negative Predictive Value (NPV): The percentage of people
with a negative test who do NOT have the disease.
NPV = D/ (C+D)

A + C B + D
Sensitivity is useful to rule-out a disease.
When a diagnostic test or sign has a high sensitivity, a negative
result rules out the diagnosis. Mnemonic “SnOUT”
Why?
Sensitivity and Negative Predictive Value share false negative (C).
As Sensitivity increases toward 100%, FN decreases toward 0.
As FN decreases toward 0, Negative Predictive Value increases
toward 100%.

A + C B + D
Specificity is useful to rule-in a disease.
When a diagnostic sign or test has a high specificity, a Positive
result rules in the diagnosis. Mnemonic “SpIN”
Why? Specificity and Positive Predictive Value share false
positive (B). As Specificity increases toward 100%, FP decreases
toward 0. As FP decreases toward 0, Positive Predictive Value
increases toward 100%.

Acute Decompensated Heart Failure
– The Role of BNP

B-type natriuretic peptide (BNP)
 is secreted by the right and left ventricles as a pro-
hormone in response to increased pressure.
 cleaved into BNP and NT-proBNP.
 BNP decreases preload and afterload, increases the
glomerular filtration rate, and decreases sodium
reabsorption.
 Natriuretic peptides have been shown to be elevated in
persons with ADHF.

The Role of BNP
Wang CS, FitzGerald JM, Schulzer M, Mak E, Ayas NT. Does this
dyspneic patient in the emergency department have congestive
heart failure? JAMA 2005;294(15):1944–56.

ACEP Guidelines
 BNP <100 pg/dL or NT-proBNP <300 pg/dL acute heart
failure syndrome unlikely (Approximate negative
likelihood ratio [LR-] = 0.1)
 BNP >500 pg/dL or NT-proBNP >1,000 pg/dL acute
heart failure syndrome likely (Approximate positive
likelihood ratio [LR+] =6)
 Silvers SM, Howell JM, Kosowsky JM, Rokos IC, Jagoda AS, American
College of Emergency Physicians Clinical Policies Subcommittee. Clinical
policy: critical issues in the evaluation and management of adult patients
presenting to the emergency department with acute heart failure
syndromes. Ann Emerg Med 2007 May;49(5):627-69.

– Nesiritide

Nesiritide
 Nesiritide is a recombinant form of B-type (brain)
natriuretic peptide that dilates veins, peripheral arteries,
and coronary arteries.
 As a result, nesiritide reduces preload and afterload and
has been studied in acute heart failure syndromes.
 Due to the neuro-hormonal effects, and the increased
serum levels of BNP in the setting of heart failure, it has
been speculated that recombinant BNP may be a
therapeutic addition to the treatment of acute
exacerbations of heart failure.

VMAC Group
 Significant reductions in PCWP were noted in the nesiritide
group when compared to either nitroglycerin or placebo (p <
0.05).
 After 24 hours, the reduction in PCWP was still significantly
greater in the nesiritide group when compared to the
nitroglycerin group (p = 0.04).
 There was no difference, however, in resolution of dyspnea
between the nitroglycerin and nesiritide groups, although both
treatments were significantly more effective than placebo at 3
hours.
 VMAC Investigators. Intravenous nesiritide vs nitroglycerin for treatment of
decompensated congestive heart failure: a randomized controlled trial. JAMA
2002;287(12):1531–40.

Sackner-Bernstein JD, Kowalski M, Fox M, Aaronson K. Short-term risk of death after
treatment with nesiritide for decompensated heart failure: a pooled analysis of randomized
controlled trials. JAMA 2005;293(15):1900–905.
Sackner-Bernstein JD, Skopicki HA, Aaronson KD. Risk of worsening renal function with
nesiritide in patients with acutely decompensated heart failure. Circulation 2005;111(12):1487-
91

ACEP Guidelines
 Because of the lack of clear superiority of nesiritide over
nitrates in acute heart failure syndrome and the current
uncertainty regarding its safety, nesiritide generally
should NOT be considered first line therapy for acute
heart failure syndromes.

– The Role of NIV

Non-Invasive Ventilation (NIV)
 The two basic forms of NIV:
 continuous positive airway pressure (CPAP) and
 Noninvasive positive pressure ventilation [NPPV, or
BiPAP (bi-level positive airway pressure)].
 CPAP – usually set at 5 – 10 cm H2O
 BiPAP
 IPPV – average 5 cm H2O
 EPPV – average 15 cm H2O

NIV in Heart Failure?
 Pang et al. performed a meta-analysis of NIV versus standard
oxygen therapy in 1998. Data were pooled from three studies
that compared CPAP and/or BiPAP to standard medical
therapy.
 The authors specifically investigated the effect(s) of NPPV on
mortality and the need for intubation.
 They found that CPAP was associated with a reduced rate of
intubation (RR = 26%; 95% CI: 14% to 38%) and a trend− − −
toward decreased mortality (RR = 6.6%; 95% CI: 16% to− −
+3%) when compared to standard oxygen therapy.
 The pooled analysis neither confirmed nor excluded the value
of BiPAP compared to standard therapy alone.
Pang D, Keenan SP, Cook DJ, Sibbald WJ. The effect of positive pressure airway support on mortality and the need for
intubation in cardiogenic pulmonary edema: a systematic review. Chest 1998;114(4):1185–92.

 Masip et al. performed a meta-analysis of trials comparing
NIV (i.e., CPAP and BiPAP) to standard oxygen therapy
in the treatment of acute cardiogenic pulmonary edema.
 Fifteen trials were included and involved data from 727
patients. Primary endpoints were in-hospital mortality
and intubation rate. The secondary endpoint was
myocardial infarction.
 From this review, it was shown that NIV significantly
decreased the relative mortality risk by 43% (CPAP 46%,
BiPAP 37%). This was statistically significant for CPAP,
but BiPAP results failed to reach statistical significance.
Masip J, Roque M, Sanchez B, Fernandez R, Subirana M, Exposito JA. Noninvasive ventilation in acute cardiogenic
pulmonary edema: systematic review and meta-analysis. JAMA 2005;294(24):3124–30.

 It was also shown that NIV significantly reduced the
relative intubation risk by 57% (P < 0.001), and the
results were statistically significant for both CPAP and
BiPAP (P<0.001 and P = 0.002, respectively).
 Overall rates of myocardial infarction were not
significantly different between standard oxygen therapy
and either mode of non-invasive ventilation (RR = 0.89;
95% CI: 0.69 to 1.17).

Systematic reviews evaluating non-invasive positive pressure
ventilation in the treatment of acute decompensated heart
failure.
Pang D, Keenan SP, Cook DJ, Sibbald WJ. The effect of positive pressure airway support on mortality and the need for
intubation in cardiogenic pulmonary edema: a systematic review. Chest 1998;114(4):1185–92.
pulmonary edema: systematic review and meta-analysis. JAMA 2005;294(24):3124–30..
Collins SP, MielniczukLM, Whittingham HA, Boseley ME, Schramm DR, StorrowAB. The use of noninvasive ventilation in
emergency department patients with acute cardiogenic pulmonary edema: a systematic review. Ann Emer Med
2006;48(3)260–69, e1–4.

ACEP Guidelines
 A moderate clinical certainty recommendation for the
use of CPAP, while Bi-PAP was given a preliminary,
inconclusive or conflicting evidence, or based on panel
consensus recommendation due to the concern for
potential myocardial ischemia and/or infarction

ACEP Guidelines
 Use 5 to 10 mm Hg continuous positive airway pressure
(CPAP) by nasal or face mask as therapy for dyspneic
patients with acute heart failure syndrome without
hypotension or the need for emergent intubation to
improve heart rate, respiratory rate, blood pressure, and
reduce the need for intubation, and possibly reduce
inhospital mortality.

Atrial Fibrillation >48 Hours
 In patients with atrial fibrillation that lasts for more than
48 hours, the immediate risk of experiencing a
thromboembolic event is between 5% and 7% if not
preceded by anticoagulation.
 This risk decreases to 0–1.6% if 2–4 weeks of
prophylactic anticoagulation and TEE are performed.
 Manning WJ, Silverman DI, Keighley CS, Oettgen P, Douglas PS.
Transesophageal echocardiographically facilitated early cardioversion from
atrial fibrillation using short-term anticoagulation: final results of a
prospective 4.5 year study. J Am Coll Cardiol 1995;25:1354–61.

Atrial Fibrillation <48 Hours
 The rate of thromboembolic events - 0.8% (95% CI: 0.2% to
2.4%).
 In addition, no significant difference was found in the incidence
of thromboembolism after rhythm conversion between
patients for whom anticoagulation therapy was initiated on
presentation, 0.8% (95% CI: 0.02% to 4.1%), and those for
whom it was not, 0.9% (95% CI: 0.1% to 3.1%)
 Wegner MJ, Caulfield TA, Danias PG, et al. Risk for clinical
thromboembolism associated with conversion to sinus rhythm in patients
with atrial fibrillation lasting less than 48 hours. Ann Intern Med
1997;126(8):615–20.

ACC/AHA Recommendations
 The risk of thromboembolic phenomena associated with
cardioverting AF of >48 hours’ duration is unacceptably
high; as such, rhythm control or conversion in this group
(>48 hours) is not recommended
 Fuster V, Ryden LE, Cannom DS, et al. ACC/AHA/ESC 2006 guidelines for
the management of patients with atrial fibrillation – executive summary: a
report of the American College of Cardiology/American Heart
Association Task Force on Practice Guidelines and the European Society
of Cardiology Committee for Practice Guidelines (Writing Committee to
Revise the 2001Guidelines for the Management of Patients with Atrial
Fibrillation). Circulation 2006;114:700–752.

All-cause Mortality and Thromboembolic
Stroke: Rate Control vs Rhythm Control
Testa L, Biondi-Zoccai GG, Dello Russo A, Bellocci F, Andreotti F, Crea F. Rate-control vs. rhythm-control in
patients with atrial fibrillation: a meta-analysis. Eur Heart J 2005;26(19):2000–2006.

Major Bleeding Complications In Rate Vs
Rhythm Control In Atrial Fibrillation

 Overall, the rate control strategy had a significantly lower
risk of all-cause death and thromboembolic stroke (OR =
0.85; 95% CI: 0.73 to 0.98)
 The rate of major bleeding (intracranial and extracranial)
was similar between the rate and rhythm control
strategies (OR=1.12; 95% CI: 0.82 to 1.53)
 The results of these five trials contradict the commonly
held perception that maintaining sinus rhythm is superior
to rate control.
Rate Control vs Rhythm Control

Beta-Blocker vs CCB For Ventricular Rate
Control for Atrial Fibrillation
 In a randomized, blinded controlled study that compared
the effectiveness of IV diltiazem and metoprolol in 40
patients with AF, both were safe and effective for the
management of rapid ventricular rate.
 However, rate control was achieved more quickly and
the percentage decrease in ventricular rate was higher
with diltiazem (0.25 mg/kg IV, maximum 25 mg) than with
metoprolol (0.15 mg/kg, maximum 10 mg).
 Demircan C, Cikriklar HI, Engindeniz Z, et al. Comparison of the
effectiveness of intravenous diltiazem and metoprolol in the management
of rapid ventricular rate in atrial fibrillation. EmergMed J 2005;2(6):411–14.

 The CHADS2 (Cardiac Failure, Hypertension, Age, Diabetes,
Stroke (Doubled)) scoring system ranks patients from 0 to 5,
giving 2 points for TIA or stroke and 1 point for all other risk
factors
 The CHADS2 index was the most accurate predictor of
stroke compared to the Atrial Fibrillation Investigators (AFI)
and the Stroke Prevention in Atrial Fibrillation (SPAF)
predictors.
 Gage BF, Waterman AD, ShannonW, et al. Validation of clinical
classification schemes for predicting stroke: results from the National
Registry of Atrial Fibrillation. JAMA 2001;285:2864–70.
 van Walraven WC, Hart RG, Wells GA, et al. A clinical prediction rule to
identify patients with atrial fibrillation and a low risk for stroke while
taking aspirin. Arch Intern Med 2003;163:936–43.
CHADS2 Score for Non-Valvular AF To
Predict Thromboembolic Risk

CHADS2 Score for Non-Valvular AF Not
Treated With Anticoagulants
C = Cardiac Failure
H = Hypertension
A = Age >70
D = DM
S = Stroke Previously

Fuster V, Ryden LE, Cannom DS, et al. ACC/AHA/ESC 2006 guidelines for the management of patients with atrial
fibrillation – executive summary: a report of the American College of Cardiology/American Heart Association Task Force
on Practice Guidelines and the European Society of Cardiology Committee for Practice Guidelines (Writing Committee to
Revise the 2001Guidelines for the Management of Patients with Atrial Fibrillation). Circulation 2006;114:700–752
Thromboembolic Risk Factors For AF
“C-H-A-D”

ACC/AHA/ESC 2006 Recommendations
Fuster V, Ryden LE, Cannom DS, et al. ACC/AHA/ESC 2006 guidelines for the management of patients with atrial
fibrillation – executive summary: a report of the American College of Cardiology/American Heart Association Task Force
on Practice Guidelines and the European Society of Cardiology Committee for Practice Guidelines (Writing Committee to
Revise the 2001Guidelines for the Management of Patients with Atrial Fibrillation). Circulation 2006;114:700–752

Which one – Antiplatelet or Warfarin?
Hart RG, Pearce LA, Aguilar MI. Meta-analysis: antithrombotic therapy to prevent stroke in patients who have
nonvalvular atrial fibrillation. Ann Intern Med 2007;146:857–67.

Which one – Antiplatelet or Warfarin?
 In summary, warfarin was more effective than ASA
and/or clopidogrel in preventing strokes in patients with
AF.
 The safety profile of warfarin poses a risk for major
bleeding, especially intracranial hemorrhage.
 The need to establish a risk–benefit profile for each
patient is essential prior to commencing treatment.
Hart RG, Pearce LA, Aguilar MI. Meta-analysis: antithrombotic therapy to prevent stroke in patients who have
nonvalvular atrial fibrillation. Ann Intern Med 2007;146:857–67.

Chest Pain Syndromes: Clinical
Features

Chest Pain
 A systematic review by Panju et al, was published to
address this question based on literature of patients
evaluated for myocardial infarction.
 In that paper, data from over a dozen trials were
collected to provide estimates of diagnostic performance
and agreement for a variety of clinical elements.
Panju AA, Hemmelgarn BR, Guyatt GH, Simel DL. Is this patient having a myocardial infarction? JAMA
1998;280:1256.

Panju AA, Hemmelgarn
BR, Guyatt GH, Simel
DL. Is this patient having
a myocardial infarction?
JAMA 1998;280:1256.

Chest Pain
 Panju’s work suggests there are no clinical features with
sufficient diagnostic performance to rule in or rule out
the diagnosis of myocardial infarction.
 What is perhaps notable is that radiation of chest pain to
the right shoulder is actually suggestive of a cardiac
etiology and that radiation in both arms should make the
emergency physician suspect ACS.
Panju AA,Hemmelgarn BR, Guyatt GH, Simel DL. Is this patient having a myocardial infarction? JAMA
1998;280:1256.

Community-Acquired Pneumonia:
CURB-65 vs PSI

Clinical Decision Rules To Determine Admission of
Community Acquired Pneumonia Patients
 The two tools in common use for this purpose are the
pneumonia severity index (PSI), developed in the USA,
and the CURB-65 rule adapted from the British Thoracic
Society.
 Fine MJ, Auble TE, Yealy DM, et al. A prediction rule to identify low-
risk patients with community-acquired pneumonia. N Engl J Med
1997;336:243–50.
 Lim WS, van der Eerden MM, Laing R, et al. Defining community
acquired pneumonia severity on presentation to hospital: an
international derivation and validation study. Thorax 2003;58:377–82.

Pneumonia Severity Index
 Scoring
 Class 1: Points 0: Mortality 0.1% (low risk)
 Class 2: Points <70: Mortality 0.6% (low risk)
 Class 3: Points 71-90: Mortality 2.8% (low risk)
 Class 4: Points 91-130: Mortality 8.2% (moderate risk)
 Class 5: Points >130: Mortality 29.2% (high risk)
 Interpretation
 Class 1-2: Outpatient management
 Class 3: Consider short observation hospital stay
 Class 4-5: Inpatient management

CURB-65
 C = confusion
 U = urea >7 mmol/L
 R = respiratory rate >30 breaths/min,
 B = Blood pressure low; systolic BP (<90 mmHg) or
diastolic (<60 mmHg)
 65 = and age (>65 years)
 with one point being assigned for the presence of each.
 Lim WS, van der Eerden MM, Laing R, et al. Defining community acquired pneumonia
severity on presentation to hospital: an international derivation and validation study.
Thorax 2003;58:377–82.

CURB-65 Scoring
 Score 0 - 0.7%
 Score 1 - 3.2%
 Score 2 - 13.0%
 Score 3 - 17.0%
 Score 4 - 41.5%
 Score 5 - 57.0%

CURB-65 Pneumonia Severity Index (PSI)
Simpler to remember and use Complex
Disadvantage:
Fails to take into account the effect of co-
morbidities that may be destabilized by
even mild episodes of CAP
Advantage:
More selective in identifying patients with
a low risk of mortality (for outpatient
treatment), thus avoiding unnecessary
hospitalization
Advantage:
More discriminating between the risks of
death among sicker patients, because it
defined high-risk patients as those with a
score of 2, 3, 4 or 5, with each of these
classes having a progressively
increasing risk of death
Disadvantage:
Only defined two groups (classes IV
and V) as severely ill with mortalities of
8.1% and 24%, respectively.
Both systems predicted mortality with a similar level of
accuracy
Aujeski D, Auble TE, Yealy DM, et al. Prospective validation of three validated prediction rules for prognosis in
community-acquired pneumonia. Am J Med 2005;118:384–92.

PSI vs CURB-65
 To identify which patients can be safely treated as outpatient,
use PSI
 To make disposition decisions among sick patients, use CURB-
65
 Combining both?
 Aujeski D, Auble TE, Yealy DM, et al. Prospective validation of three
validated prediction rules for prognosis in community-acquired
pneumonia. Am J Med 2005;118:384–92.
 Niederman MS, Feldman C, Richards GA. Combining information from
prognostic scoring tools for CAP: an American view on how to get the
best of all worlds. Eur Respir J 2006;27:9–11.

Syncope: San Francisco Syncope
Rule

San Francisco Syncope Rule
 The absence of all of the following risk-factors was 96%
sensitive and 62% specific for identifying serious outcomes at
seven days (CHESS):
 C = a history of congestive heart failure
 H = hematocrit of less than 30%
 E = an abnormal ECG
 S = a complaint of shortness of breath
 S = triage systolic blood pressure of less than 90 mmHg
 A validation of this rule subsequently in a similar population to
that from which it was derived found that the rule was 98%
sensitive (95% CI: 89–100) and 56% specific (95% CI: 52–60).
 Quinn, J., McDermott, D., Stiell, I., et al. (2006) Prospective validation of the San Francisco syncope
rule to predict patients with serious outcomes. Annals of Emergency Medicine 47: 448–454.
Quinn, J.V., Steill, I.G., McDermott, D.A., et al. (2004) Derivation of the San Francisco syncope rule to
predict patients with short-term serious outcomes. Annals of Emergency Medicine 43: 224–232.

 An independent validation of the SFSR rule was performed in an
ED population in a single academic center
 The primary outcome of the study was the sensitivity of the San
Francisco syncope rule for predicting serious events at seven days.
 A secondary outcome of the study was the prediction of any serious
clinical events that were not detected during the initial ED visit.
 They reported a sensitivity of 89% (95% CI: 81–97) and a specificity
of 42% (95% CI: 37–48) for the San Francisco syncope rule in
predicting seven-day serious outcomes.
 They also reported a sensitivity of 69% (95% CI: 46–95) and 42%
(95% CI: 37–48) for a serious diagnosis that was not identified
during the initial ED evaluation
Sun, B.C., Mangione, C.M., Merchant, G., et al. (2007) External validation of the San
Francisco syncope rule. Annals of Emergency Medicine 49: 420–427.

 While the San Francisco syncope rule does provide a
good risk stratification scheme for determining which
patients are at a low risk for serious short-term
outcomes, it does not provide us with a definitive guide
for determining which patients should be admitted or
discharged.

Transient Ischemic Attack (TIA)
 Two clinical prediction rules have been independently
developed:
 The California Rule derived by Johnston et al.
 The ABCD Rule by Rothwell et al.
 Investigators from both of these studies collaborated to
derive a unified score optimized for prediction of 2-day
stroke risk following presentation with a suspected TIA.
This is called the ABCD2 score.

Transient Ischemic Attack (TIA)
 The ABCD2 score (0–7 points) is calculated by evaluating
five factors:
 A = age (≥60 years, 1 point)
 B = blood pressure at presentation (≥140/90mmHg, 1 point),
 C = clinical features (unilateral weakness, 2 points; speech
disturbance without weakness, 1 point)
 D = duration of symptoms (≥60 minutes, 2 points; 10–59
minutes, 1 point) and
 D = diabetes (1 point)
 Subsequent 2-day stroke risk based on the ABCD2 score
is 1% (0–3 points), 4% (4–5 points) or 8% (6–7 points).

TIA – ABCD2 Score
 The ABCD2 score was retrospectively validated using the
datasets from four previously conducted cohort studies.
 It appears to be the best available tool in risk stratifying
patients at short-term (2-day) risk of stroke after a suspected
TIA.
 Patients identified as being high risk (score 6–7 points) by the
ABCD2 score are candidates for immediate evaluation,
optimization for stroke prevention and possibly therapeutic
intervention should symptoms recur.
 Patients with a score <3 may be suitable for further outpatient
evaluation following discharge on an antiplatelet agent.
 However, this score has not been prospectively validated.

Acute Asthma in Emergency
Department

Role of IV Beta-2 Agonists For Acute
Asthma: A Cochrane Review 2001
 Reviewed 15 randomized trials over a period of 25 years
Conclusions:
1 No statistically significant difference in effect between IV
beta2-agonists and all other treatments combined (inhaled
beta2-agonists, or IV methylxanthines).
2 IV beta2-agonists administered either by bolus or infusion did
not lead to significant improvements in any of the outcome
measures of clinical success (i.e. pulmonary functions, vital
signs, adverse events, clinical scores)
3 Use of IV beta2-agonists was associated with an non-significant
increase in risk of autonomic side effects (2-12 times), and
higher heart rates (4-10 beats per minute)
Travers A, Jones AP, Kelly K, Barker SJ, Camargo CA, Rowe BH. Intravenous beta2-agonists for acute asthma
in the emergency department. Cochrane Database Syst Rev. 2001(2):CD002988.

Role of IV Beta-2 Agonists For Acute
Asthma: A Cochrane Review 2001
 Reviewed 15 randomized trials over a period of 25 years
Conclusions:
 The only recommendations for IV beta2-agonists use
should be for those patients in whom inhaled therapy
cannot be used, however there have been no tests of its
efficacy in such situations.
Travers A, Jones AP, Kelly K, Barker SJ, Camargo CA, Rowe BH. Intravenous beta2-agonists for acute asthma
in the emergency department. Cochrane Database Syst Rev. 2001(2):CD002988.

Role of Inhaled Beta Agonists With Holding Chambers
Vs Nebulized Beta Agonists in Acute Asthma
 This review has been updated in January 2008, involves
2295 children and 614 adults in 27 trials from both
emergency room and community settings.
Conclusions:
1 Method of delivery of ß2-agonist did not appear to affect
hospital admission rates.
2 In adults, the relative risk of admission for spacer versus
nebuliser was 0.97 (95% CI 0.63 to 1.49).
3 The relative risk for children was 0.72 (95% CI: 0.47 to
1.09).
Cates CJ, Crilly JA, Rowe BH. Holding chambers (spacers) versus nebulisers for beta-agonist treatment of
acute asthma. Cochrane Database Syst Rev. 2006(2):CD000052.

4 In children, length of stay in the emergency department
was significantly shorter when the spacer was used,
with a mean difference of -0.53 hours (95% CI: -0.62 to
-0.44 hours).
5 Length of stay in the emergency department for adults
was similar for the two delivery methods.
6 Peak flow and forced expiratory volume were also
similar for the two delivery methods.
7 Pulse rate was lower for spacer in children, mean
difference -6.27% baseline (95% CI: -8.29 to -4.25%
baseline).

 An Important caveat in this Cochrane Review:
 These data DO NOT include patients with severe or near
fatal asthma
 For patients with severe asthma, the benefits and ease of
continuous nebulization makes it a more attractive choice
for emergency bronchodilator
 The recent worldwide severe SARS outbreak and its
apparent spread following nebulization has discouraged
routine use of nebulized treatment; in some settings these
factors facilitate conversion to MDIs to holding chambers
 Varia M, Wilson S, Sarwal S, et al. Investigation of a nosocomial outbreak of
severe acute respiratory syndrome (SARS) in Toronto, Canada. Can Med
Assoc J 2003;169(4):285–92.

Varia M, Wilson S, Sarwal S, et
al. Investigation of a nosocomial
outbreak of severe acute
respiratory syndrome (SARS) in
Toronto, Canada. Can Med
Assoc J 2003;169(4):285–92.

 165 trials were reviewed and eight were included; a total
of 461 patients have been studied (229 with CBA; 232
with intermittent beta-agonists).
Conclusions
 Overall, admission to hospital was reduced with CBA
compared to intermittent beta-agonists (RR: 0.68; 95%
CI: 0.5 to 0.9)
 patients with severe airway obstruction at presentation
appeared to benefit most from this intervention (RR: 0.64; 95%
CI: 0.5 to 0.9).
Continuous Nebulization vs Intermittent
Nebulization of Beta-agonists for Acute Asthma
Camargo CA, Jr., Spooner CH, Rowe BH. Continuous versus intermittent beta-agonists in the treatment of acute
asthma. Cochrane Database Syst Rev. 2003(4):CD001115.

 Patients receiving CBA demonstrated small but
statistically significant improvements in pulmonary
function tests when all studies were pooled.
 Patients receiving CBA had greater improvements in %
predicted FEV-1 and
 PEFR
 this effect was observed by 2-3 hours.

 Continuous treatment was generally well tolerated, with
no clinically important differences observed in
 pulse rate or
 blood pressure between the treatment groups.
 Tremor was equally common in both groups (OR: 0.81; 95%
CI: 0.5 to 1.3) and
 potassium concentration was unchanged

Role of Magnesium Sulfate
 Magnesium is an important cofactor in many enzymatic
reactions and is linked to cellular homeostasis.
 In addition, magnesium has an effect on smooth muscle
cells, with hypomagnesaemia causing contraction and
hypermagnesaemia causing relaxation.
 There is some evidence that when magnesium is infused
into asthmatic patients, it can provide additional
bronchodilation (Okayama 1987; Rolla 1988).
 In addition, evidence suggests that magnesium may
reduce the neutrophilic burst seen with the inflammatory
response (Cairns 1996).
Manser R, Reid D, Abramson M. Corticosteroids for acute severe asthma in hospitalised patients. Cochrane
Database Syst Rev. 2001(1):CD001740.

Magnesium Sulfate: A Cochrane Review
A total of 665 patients were involved.
 Seven trials were included (5 adult, 2 pediatric).
 As a whole, this systematic review failed to demonstrate
statistically significant evidence of a beneficial effect of
magnesium sulfate in terms of admission rates or
pulmonary functions.
 But those with severe asthma appeared to benefit from
the use of IV magnesium sulfate, both in terms of
pulmonary functions and admission rates.
 Improvement of approx 10% predicted FEV-1 or 50 L/min
PEFR
Rowe BH, Bretzlaff JA, Bourdon C, Bota GW, Camargo CA, Jr. Magnesium sulfate for treating exacerbations
of acute asthma in the emergency department. Cochrane Database Syst Rev. 2000(2):CD001490

Magnesium Sulfate: A Cochrane Review
Conclusion:
 Current evidence does not support routine use of
intravenous magnesium sulfate in all patients with acute
asthma presenting to the emergency department
although it appears to be safe and beneficial in patients
who present with severe acute asthma.
 In this review, severe acute asthma is defined by:
 PEFR < than 25-30% predicted after initial beta2-agonist
therapy in adults
 and/or non-response to treatment (adults and children),
 or peak expiratory flow rates of < 60% predicted (children).
Rowe BH, Bretzlaff JA, Bourdon C, Bota GW, Camargo CA, Jr. Magnesium sulfate for treating exacerbations
of acute asthma in the emergency department. Cochrane Database Syst Rev. 2000(2):CD001490

Mild Head Injury
 Definition:
 A blow to the head (or rapid deceleration) with
witnessed or self reported with either
 loss of consciousness of less than 30 minutes, or
 Amnesia of less than 24 hours, or
 any alteration in mental state (feeling dazed, disoriented,
confused) at the time of the injury
with
 A GCS of 13 – 15 at 30 minutes of more after the injury
Kay T,Harrington DE, Adams R, et al. Definition of mild traumatic brain injury. J Head Trauma Rehab
1993;8(3):86–7.

Haydel MJ, Preston CA, Mills TJ, Luber S, Blaudeau E, DeBlieux PMC. Indications for computed tomography in
patients with minor head injury. N Engl J Med 2000;343(2):100–105.
H = Headache
A = Amnesia
Y = Years old >60
D = Drugs
E = Emesis
L = Level injury above clavicle
S = Seizure
HAYDEL’S NOC

NOC vs CCHR
Predicting need for neurosurgical intervention
 Sensitivity for predicting need for neurosurgical
intervention was 100% for both the NOC and the
CCHR, but
 the CCHR was more specific (76.3% vs 12.1%; P < .001).
Predicting clinically important brain injury
 For clinically important brain injury, sensitivity was 100%
for both the CCHR and the NOC (95% confidence
interval [CI], 96% - 100%), but
 the CCHR had higher specificity (50.6% vs 12.7%; P
<.001) and would result in lower CT rates (52.1% vs
88.0%; P < .001).
Stiell, I.G., Clement, C.M., Rowe, B.H., et al. (2005) Comparison of the Canadian CT head rule and the New
Orleans criteria in patients with minor head injury. JAMA 294(12): 1511–1518.

 Applying the NOC resulted in significantly more false
positives (i.e. the rule indicated that the patient was not
at low risk and the head CT showed no injury), which
yielded a lower specificity.
 The authors concluded that given the equivalent
sensitivities, using the CCHR would be likely to result in
fewer head CTs being ordered.
NOC vs CCHR

Smits M, Dippel DWJ, de Haan GG, et al. External validation of the Canadian CT Head Rule and the New
Orleans Criteria in patients with minor head injury. JAMA 2005;294(12):1519–25.

NEXUS II Criteria
 The study identified eight criteria that were independently and highly
associated with intracranial injuries. These include:
 evidence of significant skull fracture
 scalp haematoma
 neurologic deficit
 altered level of alertness
 abnormal behaviour
 coagulopathy
 persistent vomiting
 age 65 or more
 The study showed that patients who did not have any of the above criteria
were unlikely to have significant injuries revealed by CT imaging and could
therefore be safely discharged following a thorough evaluation without the
use of CT.
Mower WRHJ, Herbert M,Wolfson AB, Pollack CV, Jr., Zucker MI, and NI Investigators. Developing a decision
instrument to guide computed tomographic imaging of blunt head injury patients. J Trauma Injury Infect Crit
Care 2005;59(4):954–9.

CT in Head Injury Patients (CHIP Prediction
Rules)
This prediction rule developed in the Netherlands includes
those patients with blunt injury to the head who have a normal
or minimally altered level of consciousness on presentation in
the emergency department, that is,
- a Glasgow Coma Scale (GCS) score of 13 to 15, and
- a maximum loss of consciousness of 15 minutes,
- posttraumatic amnesia for 60 minutes, or both.
External validation remains to be done in different populations.
Smits M, et al. Predicting intracranial traumatic findings on computed tomography in patients with minor head
injury: The CHIP prediction rule. Ann Int Med 2007; 146: 397-405.

CT in Head Injury Patients (CHIP Prediction
Rules)
A CT is indicated in the presence of
1 major criterion
A CT is indicated in the presence of
at least 2 minor criteria
Pedestrian or cyclist versus vehicle Fall from any elevation
Ejected from vehicle Persistent anterograde amnesia
Vomiting Posttraumatic amnesia of 2 to 4 hours
Posttraumatic amnesia 4 hr or more Contusion of the skull
Clinical signs of skull fracture Neurologic deficit
GCS score <15 Loss of consciousness
GCS deterioration 2 points or more (1 h
after presentation)
GCS deterioration of 1 point (1 hour
after presentation)
Use of anticoagulant therapy Age 40 to 60 years
Posttraumatic seizure
Age 60 years or more
Smits M, et al. Predicting intracranial traumatic findings on computed tomography in patients with minor head
injury: The CHIP prediction rule. Ann Int Med 2007; 146: 397-405.

The Need for Cervical Radiographic
Imaging In Stable Blunt Trauma

NEXUS Low Risk Criteria (NLC)
 N = Neurological deficit
 S = Spine tenderness
 A = Alertness
 I = Intoxication
 D = Distracting Injuries
 Whenever a component of the NLC was unassessable, the
patient was considered not to have met that criterion.
 Patients that met all five criteria were considered to be at low
risk for clinically significant cervical spine injury and these
patients would not require imaging of the cervical spine in the
ED.

The Canadian C-spine rules. ED,
emergency department; MVC,
motor vehicle collision. (Source:
Journal of the American Medical
Association 2001; 286:1841

Canadian C-spine Rule
Stiell, I.G., Clement, C.M., McKnight, R.D., et al. (2003) The Canadian C-spine rule versus the NEXUS low-risk
criteria in patients with trauma. New England Journal of Medicine 349(26): 2510–2518.
Validation results of the Canadian C-spine rule (CCR) and test performance from
Stiell et al

NEXUS Low-Risk Criteria
Stiell, I.G., Clement, C.M., McKnight, R.D., et al. (2003) The Canadian C-spine rule versus the NEXUS low-risk
criteria in patients with trauma. New England Journal of Medicine 349(26): 2510–2518.
NEXUS low-risk criteria (NLC): results and test performance from Stiell et al.

NLC vs CCR
 The NLC and the CCR have both been validated in large
cohorts of patients in ED patients with blunt trauma to
the neck.
 In the validation cohorts, both have high sensitivities
(>99.3%) and negative predictive values (>99.9%), making
both decision rules safe.
 When comparing the two rules, Stiell and colleagues
concluded that the CCR performed better than the NLC.
 The NLC are somewhat easier to use clinically because
they are less difficult to remember.
 The CCR are more complex and must be employed in a
stepwise fashion.

 While both the NLC and the CCR have roughly equal
high sensitivity and high negative predictive values, the
CCR are more specific than the NLC
 CCR will have many fewer false positives
 The very low specificity of the NLC will lead to more
unnecessary imaging (i.e. false positives—when the
prediction rule indicates that the patient is not low risk
and therefore recommends imaging).
NLC vs CCR

Ottawa Knee, Ankle and Foot Rules

Ottawa Knee Rules
 O – Older age group
 Older than 55 years old
 T – Tenderness head of fibula
 T – Tenderness of patella
 Isolated patella tendernes, no other bony tenderness
 AW – Ability to walk?
 Inability to walk four steps immediately after injury and in ED
 A – Ability to flex?
 Knee Flexion to 90 degrees

Ottawa Knee Rules
Six studies reporting sensitivity and specificity of the Ottawa knee rules

Sensitivities and specificities of OAR and OFR in pooled studies from Bachmann et al.
Bachmann, L.M., Kolb, E., Koller, M.T., et al. (2003) Accuracy of Ottawa ankle rules to exclude fractures of the
ankle and mid-foot: systematic review. British Medical Journal 326(7386): 417.

Current Issues In Emergency Medicine - A Selected Update

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