Q: Permissive hypercapnia is relatively contra-indicated in all of the following except?

A) Acute myocardial infarction

B) Severe COPD

C) Active Seizure

D) Hypovolemia 

E) Bradycardia


Answer:  B

Permissive hypercapnia is usually very well tolerated by all patients but caution is required in few situations such as hypercapnia may decrease seizure threshold. Similarly, hypercapnia exacerbates vasodilation and patient should be made at least euvolemic  before allowing hypercapnia. Acute myocardial infarction may negatively get affected by hypercpania due to sympathomimetic output. Bradycardia may get worse as hypercapnia and associated acidosis has negative inotropic effects.

Hypercapnia is actually advocated in severe respiratory failure secondary to ARDS or COPD. 



References
1. Foëx P, Fordham RM. Intrinsic myocardial recovery from the negative inotropic effects of acute hypercapnia. Cardiovasc Res 1972; 6:257 

2. Feihl F, Perret C. Permissive hypercapnia. How permissive should we be? Am J Respir Crit Care Med 1994; 150:1722

3. Kavanagh BP, Laffey JG. Hypercapnia: permissive and therapeutic. Minerva Anestesiol 2006; 72:567.