post bypass vasoplegia

 Q: All of the following are risk factors for post-cardiac bypass surgery vasoplegia Except?

A) pre-operative use of angiotensin-converting enzyme (ACE) inhibitors 

B) warmer core temperature on bypass

C) use of vasopressin perioperatively 

D) longer time on aortic cross-clamping and bypass

E) pre-bypass hemodynamic instability

Answer: C

All of the conditions described in choices A, B, D, and E are risk factors for refractory vasoplegia after bypass surgery.

Vasopressin (choice C) is one of the pressors which has the strongest evidence among all pressors to have clinical efficacy in post-cardiac surgery vasoplegia. Vasopressin has five effects simultaneously by binding to V1a, V1b, and V2 receptors. It causes 

• vasoconstriction 
• water reabsorption at the renal collecting ducts 
• increased secretion of cortisol 
• increased secretion of insulin 
• bradycardia by augmenting baroreflex inhibition of efferent sympathetic nerve activity

Said that vasopressin should not be used beyond recommended dose due to its high affinity to cause vasoconstriction at the capillary level causing renal and gastrointestinal (GI) ischemia.

#hemodynamic

References:

1. Dünser MW, Hasibeder WR. Sympathetic overstimulation during critical illness: adverse effects of adrenergic stress. J Intensive Care Med 2009; 24(5): 293–316.

2. Schmittinger CA, Torgersen C, Luckner G, et al. Adverse cardiac events during catecholamine vasopressor therapy: a prospective observational study. Intensive Care Med 2012; 38(6): 950–958. 

3. Demiselle J, Fage N, Radermacher P, et al. Vasopressin and its analogues in shock states: a review. Ann Intensive Care 2020; 10(1): 9. 

4. Treschan TA, Peters J. The vasopressin system: physiology and clinical Strategies. Anesthesiology 2006; 105(3): 599–612