Hypovolemic Shock

Question 1

Shock continuum (and shock definition)

Answer 1

• Changes in determinants of cardiac output. PL, AL, Contract, HR. Compensatory mechanisms adequate to maintain tissue perfusion. No significant impact on hemodynamic stability
• Hemodynamic instability. Compensatory mechanisms continue but not failing to fully compensate. hemodynamic stability impacted. dec BP etc
• Shock. Failure of compensatory mechanisms. CM’s now perpetuating or resulting in increased dysfunction. Pregresses rapidly if no intervention. Results in end organ perfusion problem from inadequate supply.

Question 2

Classes of compensatory mechanisms

Answer 2

Neural: SNS mediated by mechanical baroreceptors in carotid sinus and aortic arch - catecholamine epinephrin, norepinephrine
Chemical: Peripheral and Central Chemoreceptors - mediate resp centres in medulla responding to hypoxemia, and hypercapnia respectively
Hormonal:
RAAS, ADH, ACTH–Cortisol (gluconeogensis, catecholamine release)

Question 3

Types of shock

Answer 3

Hypovolemic - dec preload, dec contract, inc afterload w/ compensation e.g.bleeds, dehydration (N/V, diuresis), insufficient circulating volume

Cardiogenic - inc preload, dec contractility, increased afterload w/ compensation e.g. systolic HF

Distributive - dec preload, normal or decreased contractility, dec afterload e.g. neurogenic, anaphylactic, septic shocks

Question 4

Formula for MAP

Answer 4

(DPBx2+SBP)/3

Question 5

Decision process for treating CO problem

Answer 5

1. Treat obvious dysrhythmias first (drugs or electrical)
2. Hows preload?
   - Low- give fluids/blood. (hypovolemic shock, sepsis)
   - High - diuresis (Lasix,spironolocatone) if time/Nitro for fast action (often in HF)
3. If contractility is low and afterload is inc/dec?
   
   • Follows preload starling’s law
   • If dec contract with vasoconstriction (inc AL) - Milrinone if we have time, Dobutamine for fast action (often in HF)
   • If dec contractility with vasodilation (dec AL) - catecholamine (dopamine, epinephrine) (like Sepsis)
4. If contractility is fine, treat afterload
   
   • VD w/ high HR - levophed (norepinephrine), phenylephrine (as in sepsis)
   • VD w/ Low HR - Epinephrine, Dopamine
   • VC w/ High HR - Labetolol
   • VC w/ low HR - Hydralazine, Nitroprusside

Question 6

Another alpha agonist not levophed

Answer 6

Phenylephrine

Question 7

Another med like nitroglycerin but effecting vasodilation in arteries also

Answer 7

Nitroprusside