Pressor and SC route of meds

 Q: Patients on high doses of vasopressor in ICU may require higher doses of deep venous thrombosis (DVT) prophylaxes than usual?

A) True

B) False

Answer: A

Patients on high dose of vasopressors develop cutaneous vasoconstriction. This leads to decreased bioavailability of medications which are usually delivered subcutaneously (SQ) such as insulin and heparins. 

At least one study look into this phenomenon comparing three commonly used pressors in ICU i.e., dopamine (@ >10 mcg/kg/min), norepinephrine (@ >0.25 mcg/kg/min), and phenylephrine (@>2 mcg/kg/min). Patients were found to have a decreased factor Xa activity with the comparable group. The study had a very small sample size of only 15 patients, and requires a larger trial in association with various variabilities/confounders. Said that, theoretically it points towards at least one of the causes of higher rates of poor blood-glucose control and increase DVTs in ICU despite appropriate measures.

#pharmacology

Reference:

Dörffler-Melly J, de Jonge E, Pont AC, et al. Bioavailability of subcutaneous low-molecular-weight heparin to patients on vasopressors. Lancet 2002; 359:849.