Faculty Bibliography

Acute limb ischemia caused by peripheral venoarterial extracorporeal membrane oxygenation (ECMO) cannulation is associated with increased mortality. Early detection of limb hypoperfusion may lead to timely intervention and prevent irreversible muscle damage. Methods to determine the adequacy of tissue oxygenation in cannulated extremities include bedside physical examination, trending serum biochemical markers, and somatic near-infrared spectroscopy. To prevent ECMO-related limb ischemia events, interventions include the addition of distal antegrade perfusion catheters to the arterial ECMO canula, minimizing arterial cannula diameter, placing arterial and venous cannulae on opposite extremities, and adding a side-arm graft to the cannulated artery. If the limb develops early signs of ischemia, preventative measures such as distal perfusion catheter insertion or changing the location of the arterial cannula should be performed. Acute compartment syndrome requires emergency fasciotomy or amputation if the limb is unsalvageable. Opportunities for future research include improving monitoring technology and standardizing the use of the distal perfusion catheter.

BACKGROUND:Ideal timing of postoperative beta-blockers is unclear. We hypothesized that patients who do not receive beta-blockers immediately after cardiac surgery would have increased in-hospital mortality (primary outcome) and postoperative hemodynamic, pulmonary, neurologic, or respiratory complications (secondary outcomes). METHODS:We performed a retrospective cohort study evaluating patients who underwent cardiac surgery at our institution from January 1, 2013 to September 30, 2017. We compared outcomes between patients who received beta-blockers by postoperative day (POD) 5 with outcomes in patients who did not receive beta-blockers at any time or received them after POD 5. Inverse probability of treatment weighting was used to minimize confounding. Univariate logistic regression analyses were performed on the weighted sets using absent or delayed beta-blockers as the independent variable and each outcome as dependent variables in separate analyses. A secondary analysis was performed in patients prescribed preoperative beta-blockers. E-values were calculated for significant outcomes. RESULTS:All results were confounder adjusted. Among patients presenting for cardiac surgery, not receiving beta-blockers by POD 5 or at any time was not associated with the primary outcome in-hospital mortality, estimated odds ratio (OR; 99.5% confidence interval [CI]) of 1.6 (0.49-5.1), P = .28. Not receiving beta-blockers by POD 5 or at any time was associated with postoperative atrial fibrillation, estimated OR (99.5% CI) of 1.5 (1.1-2.1), P < .001, and pulmonary complications, estimated OR (99.5% CI) of 3.0 (1.8-5.2), P < .001. E-values were 2.4 for postoperative atrial fibrillation and 5.6 for pulmonary complications. Among patients presenting for cardiac surgery taking preoperative beta-blockers, not receiving beta-blockers by POD 5 or at any time was not associated with the primary outcome mortality, with estimated OR (99.5% CI) of 1.3 (0.43-4.1), P = .63. In this subset, not receiving beta-blockers by POD 5 or at any time was associated with increased adjusted ORs of postoperative atrial fibrillation (OR = 1.6; 99.5% CI, 1.1-2.4; P < .001) and postoperative pulmonary complications (OR = 2.8; 99.5% CI, 1.6-5.2; P < .001). Here, e-values were 2.7 for postoperative atrial fibrillation and 5.1 for pulmonary complications. For the sensitivity analyses for secondary outcomes, exposure and outcome periods overlap. Outcomes may have occurred before or after postoperative beta-blocker administration. CONCLUSIONS: Among patients who undergo cardiac surgery, not receiving postoperative beta-blockers within the first 5 days after cardiac surgery or at any time is not associated with in-hospital mortality and is associated with, but may not necessarily cause, postoperative atrial fibrillation and pulmonary complications.