This document discusses hypovolemic shock, which is caused by a reduction in intravascular volume leading to insufficient oxygen delivery to cells. It defines the three categories of hypovolemic shock - compensated, uncompensated, and lethal exsanguination - and describes the body's physiological response and management goals in each category. The key goals in management are to secure the airway, control hemorrhaging, restore intravascular volume through fluid resuscitation with crystalloids and blood transfusions, and correct any electrolyte or acid-base disturbances.

1. Hypovolemic
Shock
General Surgery Orientation
Medical Student Lecture Series
Juan Duchesne MD,FACS,FCCP,FCCM

2. Shock
 Hypovolemic
 Septic
 Cardiogenic (Obstructive)
 Neurogenic
 Adrenal

3. Shock
Most common forms in surgery:
Hypovolemic
Septic
Cardiogenic

4. Hypovolemic Shock
Definition:
Reduction in intravascular volume leading
to insufficient oxygen delivery to cells
(mitochondria)

5. Hypovolemic Shock
Reduced intravascular volume?
No oxygen delivery!
No aerobic metabolism!
Then…
 Metabolic acidosis (lactic acid production)
 Endoplasmic recticulum swelling
 Mitochondrial damage
 Cell Death!

6. Hypovolemic Shock
Vascular compartments:
TBW (60% of IBW)
Total Body Water
ICW (40%) ECW (20%)
Intracellular Water Extracellular
Water
Interstitium Plasma
(1/3) (2/3)

7. Hypovolemic Shock
Loss of circulating blood volume (Plasma)
Normal Blood Volume:
- 7% IBW in adults
- 9% IBW in kids

8. Hypovolemic Shock
Tension
Pneumothorax
~ impairment
of ventricular
filling.

9. Hypovolemic Shock
Hemorrhagic shock (3 categories)
Compensated:
– 0-20% of blood loss
– Blood pressure is maintained via increased
vascular tone and increased blood flow to vital
organs

10. Hypovolemic Shock
The body’s response:
Compensated shock Baroreceptor mediated
vasoconstriction!
 Increased epinephrine, vasopressin, angiotensin
 Results in:
– Tachycardia
– Tachypnea
– Lowered pulse pressure
– Slightly lowered urine output

11. Hypovolemic Shock
The Organs who win:
 Brain
 Heart
 Kidneys
 Liver
The Organs who lose:
 Skin
 GI tract
 Skeletal Muscle

12. HypovolemicShock
But why
 The body will make whatever adjustsments it can to
maintain….
Adequate
Cardiac
Output
 Brain and heart perfusions remain near normal while
other less critical organ systems are, in proportion to the
blood volume deficit, stressed by ischemia.

13. Hypovolemic Shock
Uncompensated:
20-40% loss of blood volume
Decrease in BP
Tachycardia

14. Hypovolemic Shock
The body’s response
Uncompensated shock
 The intravascular volume deficit exceeds the
capacity of vasoconstrictive mechanisms to
maintain systemic perfusion pressure.
 Increased cardiac output
 Increased respiration
 Sodium retention

15. Hypovolemic Shock
Lethal exsanguination:
40% loss of blood volume
Profound hypotension and inability to
perfuse vital organs

16. Hypovolemic Shock
The body’s response
Lethal exsanguination:
– Obtunded
– Severe hypotension
– Severe tachycardia
– Cold, Clammy
– Death

17. Hypovolemic Shock
Caveats…
Athletes
Pregnancy
Extremes of age
Medications
Hematocrit/Hemoglobin

18. Hypovolemic Shock
Management:
 ABCs of trauma (AIRWAY is
always first!)
 Control hemorrhage (splint the
limb!!)
 Obtain IV access and resuscitate
with fluids and blood
– 2 liters crystalloid for adults
– 20 cc/kg crystalloid x 2 for kids
 Blood vs. Crystalloid??
 Long term critical care
management

19. Hypovolemic Shock
Your management goals AFTER securing the
ABCs:
STOP THE BLEEDING!
RESTORE VOLUME!
CORRECT ANY ELECTROLYTE/ACID-BASE
DISTURBANCES!

20. Hypovolemic Shock
this requires a trip to the OR…

21. Hypovolemic Shock
And sometimes the ED becomes the OR

22. Hypovolemic Shock
Volume Resuscitation ~ What are my goals?
Rapid Responder
– Give 500cc-1 Liter crystalloid  rapid
improvement of BP/HR/Urine output
– < 20% blood loss
– Surgery consult

23. Hypovolemic Shock
Volume Resuscitation ~ What are my goals?
Transient Responder
– Give 500cc-1 Liter crystalloid  improves
briefly then deteriorates
– 20-40% blood loss
– Continue crystalloid infusion +/- Blood
– Surgery consult

24. Hypovolemic Shock
Volume Resuscitation ~ What are my goals?
Non Responder
– Give 2 Liters crystalloid/ 2 units Blood  no
response
– > 40% blood loss
– STAT Surgery consult!

25. Hypovolemic Shock
Is my volume resuscitation
adequate/inadequate?
Urine output
Vital signs
Skin perfusion
Pulse Oximetry
Acidemia??

26. Septic Shock
An exaggerated endogenous inflammatory
response to invasive infection leading to:
 circulatory collapse
 multiple organ failure
 death

27. Septic Shock

28. Septic Shock
Mortality
over 35% (sepsis with hypotension)
45% (sustained septic shock)

29. Septic Shock
Management:
 Identify and treat the infectious source
eg – simple incision & drainage?
Exploratory laparotomy?
Amputation?
 Volume resuscitation
 Restoration of perfusion pressure (may need
pressors!)

30. Cardiogenic Shock
Acute hypotension
low cardiac output
inadequate LV outflow
Poor end organ perfusion!

31. Cardiogenic Shock
Causes most likely to see on the surgery wards:
 Acute MI
 Arrhythmia (A. fib)
 Cardiac Contusion
 Cardiac Tamponade
 Massive Pulmonary Embolism
 Decompensated Congestive Heart Failure

32. Shock
?