Comparison of Two Dexmedetomidine Administration Strategies on the Incidence of Postoperative Respiratory Complications: A Retrospective, Inverse Probability of Treatment Weighted Study.

Randomized controlled trials have shown a higher risk of postoperative hypoxemia and delayed extubation with opioid-free anesthesia (OFA), compared with opioid anesthesia. The practice of OFA is not standardized. The objective of this study is to investigate the association between the dexmedetomidine administration protocol used and the occurrence of postoperative respiratory complications. This work is a retrospective, propensity score-adjusted study (inverse probability of treatment weighting) conducted between January 2019 and September 2021 in a French tertiary care university hospital, including 180 adult patients undergoing major digestive surgery. Comparison of 2 anesthesia protocols: with a continuous intravenous maintenance dose of dexmedetomidine following a bolus (group B+M, n = 105) or with a bolus dose alone (group B, n = 75). The main outcome measure was a composite respiratory end point within 24 hours of surgery. There was no significant difference in the incidence of overall respiratory complications, as assessed by the primary end point. Nevertheless, there were more patients with postoperative hypercapnia in group B+M than in group B (16% vs 2.5%, P = .004). Patients in group B+M were extubated later than patients in group B (group B+M, median 40 minutes, IQR 20-74 minutes; group B, median 20 minutes, IQR 10-50 minutes; P = .004). Our study showed negative results for the primary end point. However, data on the increased risk of postoperative hypercapnia in patients receiving a maintenance dose of dexmedetomidine are new. Other prospective randomized studies with greater power are necessary to confirm these data and to make OFA safer, by reducing the prescribed doses of dexmedetomidine.

Left Ventricular Outflow Tract Obstruction in Patients Treated With Milrinone for Cerebral Vasospasm: Case Report and Literature Review.

Subarachnoid hemorrhage is associated with high morbidity and mortality, and cerebral arterial vasospasm is one of its main complications that determines neurological prognosis. The use of intravenous milrinone is becoming more common in the treatment of vasospasm. This molecule has positive inotropic and vasodilating properties by inhibiting phosphodiesterase-3. Its most described side effects are cardiac arrhythmias and arterial hypotension. In this paper, we raise a new issue concerning milrinone and discuss an undescribed side effect of this treatment, left ventricular outflow tract obstruction (LVOTO). Dynamic LVOTO is a clinical situation favored by hypovolemia, decreased left ventricular afterload, and excessive inotropism that can lead to severe hemodynamic failure and pulmonary edema. To our knowledge, this is the first study describing milrinone-induced LVOTO. This could compromise cerebral perfusion and therefore the neurological prognosis of patients. While it is known that catecholamines may induce LVOTO, milrinone-induced LVOTO appears to be a new pathophysiological entity of which neurosurgical intensivists should be aware.