This Month In: Anesthesiology

Limited data are available to guide use of inotropes in cardiac surgery. Patients from a historic multicenter cohort study of patients undergoing cardiac surgery with and without cardiopulmonary bypass between 2006 and 2009 were propensity score–matched to yield comparable subgroups of 1,170 patients, one group of which received inotropic therapy and one of which did not, for outcome analysis. Whereas patients treated with inotropes had a 1-yr mortality of 11.1%, that of the matched cohort was 4.2%. Use of inotropic therapy was also independently associated with increased 30-day mortality and increased risks of postoperative myocardial infarction, stroke, and renal replacement therapy. See the accompanying Editorial View on page 1067.

Cardiac β-adrenergic receptor (βAR) stimulation activates the alpha subunit of the stimulatory G protein (Gαs), which increases cyclic adenosine monophosphate production. Decreased Gαs expression in homozygous haplotype *1 patients was associated with twice the risk of death within 5 yr of surgery compared with homozygous haplotype *3 in 1,627 patients undergoing coronary artery bypass graft surgery at two institutions between 2001 and 2009. Homozygous haplotype *1 patients with βAR blockade had a threefold increased risk compared with homozygous haplotype *3 patients with βAR blockade. These risks were independent of conventional risk factors.

An analysis of 534,500 completed pregnancies identified from among private health insurance beneficiaries between 2005 and 2011 revealed 14.4% of women were dispensed an opioid sometime during their pregnancy. Approximately 6% of women received opioids during each trimester. While the median duration of exposure was less than a week, 2.2% were dispensed opioids three or more times. The most commonly dispensed opioids were hydrocodone, codeine, and oxycodone. Back pain was the condition most commonly associated with opioid exposure. These data suggest the overuse of opioids in the general population of the United States extends to pregnancy. See the accompanying Editorial View on page 1063.

The inability to identify patients at greatest risk for acute respiratory distress syndrome (ARDS) limits progress in preventing ARDS. One thousand five hundred sixty-two patients with major risk factors for acute lung injury (ALI)/ARDS or undergoing emergency surgery were identified in this secondary analysis of data from the Lung Injury Prevention Study (LIPS), a 2009 multicenter prospective surgical cohort, 117 of whom developed postoperative ALI/ARDS. The prediction accuracy of the Surgical Lung Injury Prediction (SLIP) score, developed for use in elective surgical patients, in the more diverse and acutely ill surgical population was poor. SLIP-2, a refined algorithm, accurately estimated risk of postoperative ALI/ARDS in this high-risk cohort. See the accompanying Editorial View on page 1072.

This meta-regression analysis of data for 10,317 patients from 29 studies reported in 27 papers found the risk ratio for the overall effect of nitrous oxide on postoperative nausea and vomiting (PONV), independent of duration of exposure, was 1.21. However, the increase in PONV seen with nitrous oxide administration was highly dependent on the duration of exposure and the effect of nitrous oxide on PONV was clinically insignificant up to at least 1 h of exposure. The risk ratio of PONV increased by 20% per hour of exposure to nitrous oxide after the first 45 min.

Complex regional pain syndrome (CRPS) is a multifactorial disorder. Pain, flare area, and skin perfusion were determined after physiological stimulation with topical capsaicin applied to the dorsal part of both hands, in a randomized order, of 16 unilateral upper limb CRPS patients and 15 matched controls. Generalized bilateral hypersensitivity to painful chemical, mechanical, and thermal stimuli not confined to the innervation area of one peripheral nerve or root was observed in CRPS patients, suggesting it is due primarily to central sensitization. Because the capsaicin flare response was normal, the increased pain is unlikely to have resulted from increased neurogenic inflammation. See the accompanying Editorial View on page 1078.

Chronic thromboembolic pulmonary hypertension (CTEPH) is a progressive disease with a poor prognosis. Surgical intervention by pulmonary thromboendarterectomy (PTE) has become the therapy of choice for patients with CTEPH because of the limited efficacy of medical therapy and the scarcity of available lungs for transplant. The pathophysiology of CTEPH is discussed as are its diagnosis and evaluation to determine surgical accessibility. Medical management before surgical correction as well as anesthetic, surgical, and postoperative management and PTE outcomes are reviewed.

Buprenorphine is a partial μ-opioid receptor agonist and full κ-opioid receptor antagonist. It is formulated with the μ-opioid receptor antagonist naloxone in a sublingual tablet to prevent intravenous abuse. Buprenorphine–naloxone can be used for office-based opioid addiction treatment and as an alternative to methadone in opioid replacement therapy. It can provide pain relief for opioid-dependent or addicted chronic pain patients, possibly by reversing opioid-induced hyperalgesia. As a weak analgesic, it is unlikely to provide adequate pain relief in non–opioid-dependent chronic pain patients. Implications of buprenorphine–naloxone therapy in clinical anesthesia and perioperative pain management remain to be determined.