Effects of Ambulation and Nondependent Transfers on Vital Signs in Patients Receiving Norepinephrine

To assess the safety of mobilizing patients receiving low-dose norepinephrine (0.05 μg/kg per min) by examining mean arterial pressure and heart rate before and after activity with parameters set by the physician.

Norepinephrine is a peripheral vasoconstrictor administered for acute hypotension. During activity, blood flows to the periphery to supply muscles with oxygen, which may oppose the norepinephrine vasoconstriction. The safety of mobilizing patients receiving norepinephrine is unclear.

Heart rate, mean arterial pressure, norepinephrine dose, and activity performed were extracted retrospectively from charts of 47 cardiothoracic surgery patients during the first patient transfer to chair or ambulation with norepinephrine infusing. Mean arterial pressure and heart rate were compared before and after physical therapy (paired t tests). Differences among norepinephrine doses and physical activity levels were evaluated (Kruskal-Wallis test).

Forty-one of the 47 patients (87%) tolerated the activity within safe ranges of vital signs. The change in patients' mean arterial pressure from before to after activity was not significant (P = .16), but a significant increase in heart rate occurred after activity (P < .001). A Kruskal-Wallis test showed no significant difference in the norepinephrine dose and activity level (χ² = 6.34, P = .17). No instances of cardiopulmonary or respiratory arrest occurred during any physical therapy sessions.

Infusion of low-dose norepinephrine should not be considered an automatic reason to keep patients on bed rest.