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

2. Cardiogenic (Obstructive)
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. Hypovolemic Shock 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. this requires a trip to the OR…
Hypovolemic Shock
this requires a trip to the OR…

21. And sometimes the ED becomes the OR
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 ?