THIS MONTH IN Anesthesiology

The incidence, risk factors, sequelae, and prevention of intraoperative awareness are reviewed.

Children undergoing inguinal hernia repair had normal academic performance at age 15–16.

An oxygenated polyethylene glycol–modified hemoglobin was evaluated in patients undergoing total hip replacement. See the accompanying Editorial View on  page 1016 

In piglets, the benefits of a vital capacity maneuver followed by one-lung ventilation with reduced tidal volume were studied. See the accompanying Editorial View on  page 1009 

This clinical scenario discusses the key issues of perioperative bronchospasm.

Pulmonary aspiration of gastric contents is a common complication of anesthesia and cause of morbidity and mortality. To determine if ultrasonographic measurement of antral cross-sectional area (CSA), a noninvasive test of gastric content volume, may help to reduce this complication, a prospective observational study was conducted in 180 patients. There was a positive correlation between antral CSA and aspirated gastric fluid volume. Assessment of a “risk stomach” was made using a CSA cutoff value of 340 mm²; this was associated with sensitivity of 91% and a specificity of 71% for “risk stomach.” Use of antral CSA may help to reduce pulmonary aspiration of gastric contents during general anesthesia.

Mechanical lung ventilation may lead to lung injury via  pulmonary inflammation. These investigators evaluated the utility of measuring exhaled breath condensates (EBCs) as a measure of lung inflammation and injury in ventilated patients. EBC pH and inflammatory markers were measured in mechanically ventilated patients without acute lung injury or sepsis (n = 27). Compared with healthy controls, EBC pH was lower whereas inflammatory markers (e.g.,  interleukin [IL]-1β, tumor necrosis factor-α, IL-6, IL-10, IL-12p70) were higher in ventilated patients. No difference was observed between patients who received either zero end-expiratory pressure or positive end-expiratory pressure. This study demonstrated the presence of inflammatory markers in patients with mechanical lung ventilation in the absence of acute lung injury or sepsis, which is unaffected by expiratory pressure induced. A relation to systemic inflammatory markers was also present.

The potential protective effects of lower tidal volumes (TV) in patients without lung injury undergoing elective surgery are not known. In a single-center randomized controlled trial, patients (N = 149) received either 6 ml/kg TV ventilation or 10 ml/kg TV while undergoing elective cardiac surgery. Median ventilation times, intensive care unit length of stay, and hospital length of stay were similar between groups. However, in the lower TV group, a higher proportion of patients were ventilation free at 6 h and fewer patients required reintubation compared with the higher TV group. Lower TV did not provide additional benefit in terms of time to extubation for patients undergoing elective surgery. See the accompanying Editorial View on  page 1011