Metabolic effects of beta-blockers in critically ill patients: A retrospective cohort study

Beta-blockers have potential protective features during critical illness. Heart rate reduction, with limited effect on blood pressure and beneficial effects on metabolism, organ function and inflammation have been reported. We examined metabolic effects of beta-blockers among ICU patients, to address the effect on the estimated energy expenditure, measured by carbon dioxide production (VCO₂). Furthermore, we investigated effects on organ function and inflammation.

A retrospective study in adult patients admitted to our 17-beds mixed medical-surgical ICU from January 2013 to March 2016. Mechanically ventilated patients who commenced beta-blockers were eligible for inclusion. Exclusion criteria were: beta-blocker therapy in the 7 previous days, treatment duration <48 h, therapeutic hypothermia, and no VCO₂ measurements. Outcome parameters were obtained at 6 different time points from 24 h before until 48 h after beta-blocker commencement. Linear mixed models were used to evaluate trends.

In total 58 patients were included. Various types of beta-blockers were administered, with a median equivalent daily dose to metoprolol of 50.0 mg (IQR 25.0-62.5). The mean heart rate decreased from 103 ± 20 to 91 ± 19 beats per minute after 48 h (p < 0.001), with unaltered blood pressures. Metabolic and other parameters did not show significant differences over time, or parameter changes were due to trends that had already started before beta-blocker commencement.

No changes in VCO₂ after beta-blocker commencement were demonstrated suggesting no alterations in energy expenditure. Heart rates significantly decreased with unaltered blood pressures. Other parameters did not show trends that could be attributed to beta-blockers effects.