Science, Medicine, and the Anesthesiologist

Preconditioning-mediated organ protection is a phenomenon by which tissue, once exposed to a specific type of insult, is protected from injury during a repeated insult; protection can be seen even when the original insult occurs at a site remote from the repeated insult. Because therapeutic strategies to protect against ischemic kidney injury and improve cardiac surgical patient outcomes are lacking, 240 patients at high risk for acute kidney injury were randomized to receive either remote ischemic preconditioning (RIPC; n = 120) or sham control (n = 120) after induction of anesthesia. The RIPC involved three cycles of 5 min of ischemia induced by inflation of a blood pressure cuff to 200 mmHg or at least 50 mm greater than systolic blood pressure in one upper arm, followed by 5 min of reperfusion with the cuff deflated. The sham RIPC (control) involved three cycles of “pseudoischemia,” consisting of 5 min of blood pressure cuff inflation to 20 mmHg, followed by 5 min of cuff deflation. RIPC when compared with no ischemic preconditioning significantly reduced the rate of acute kidney injury and use of renal replacement therapy (5.8% vs. 15.8%). The risk-benefit ratio of RIPC warrants further investigation.

N-methyl-d-aspartate (NMDA) receptor antagonists such as ketamine exhibit antidepressant effects. This effect was tested for another NMDA receptor antagonist, nitrous oxide, in this blinded, placebo-controlled crossover trial. Twenty patients with treatment-resistant depression were randomly assigned to 1-h inhalation of 50% nitrous oxide/50% oxygen or 50% nitrogen/50% oxygen (placebo control). The primary endpoint was the change on the 21-item Hamilton Depression Rating Scale 24 h after treatment. It was found that depressive symptoms improved significantly at 2 h and 24 h after receiving nitrous oxide compared with placebo. This proof-of-concept trial demonstrated that nitrous oxide has rapid and marked antidepressant effects in patients with treatment-resistant depression.

The successful treatment of intraabdominal infection requires a combination of anatomical source control and antibiotics. The appropriate duration of antimicrobial therapy remains unclear. This prospective randomized controlled trial compared a maximum 10-day (2 days after resolution of fever, maximum 10 days; control group) versus a fixed 4 ± 1 days antibiotic strategy in 518 patients with complicated intraabdominal infection and adequate control of infection source. The primary outcome was a composite of recurrent or complicated intraabdominal infection or death. Outcomes after fixed-duration antibiotic therapy (approximately 4 days) were similar to those after a longer course of antibiotics (approximately 8 days) that extended until after the resolution of physiological abnormalities.

Noninvasive ventilation delivered as combined nasal and oral positive airway pressure (BiPAP) is often used to avoid reintubation and improve outcomes of patients with hypoxemia after cardiothoracic surgery. High-flow nasal oxygen therapy is being used more and more to improve oxygenation because of its ease of implementation, tolerance, and clinical effectiveness. In this randomized controlled trial including 830 patients who had undergone cardiothoracic surgery, high-flow nasal oxygen therapy delivered continuously through a nasal cannula (flow, 50 l/min; fraction of inspired oxygen, 50%) was not inferior to BiPAP (pressure support level, 8 cm H2O; positive end-expiratory pressure, 4 cm H2O; fraction of inspired oxygen, 50%) with respect to treatment failure (reintubation).

Therapeutic hypothermia is recommended for comatose adults after witnessed out-of-hospital cardiac arrest, but data about this intervention in children are limited. This randomized controlled trial included 295 patients aged 2 days to 18 yr remaining comatose within 6 h after resuscitation from out-of-hospital cardiac arrest; children were allocated to either hypothermia (target 33 °C) or normothermia (target 36.8 °C). The primary outcome was survival at 12 months with a functional scale. It was found that in comatose children who survived out-of-hospital cardiac arrest, therapeutic hypothermia, as compared with therapeutic normothermia, did not confer a significant benefit in survival with a good functional outcome at 1 yr.

Mechanical chest compression devices have the potential to help maintain high-quality cardiopulmonary resuscitation. Despite their increasing use, little evidence exists for their effectiveness. This study examined whether the introduction of LUCAS-2 mechanical cardiopulmonary resuscitation into front-line emergency response vehicles improved survival from out-of-hospital cardiac arrest. The trial included 4,471 patients with prehospital cardiac arrest randomly allocated to either manual or mechanical (LUCAS-2) chest compression. Primary outcome was survival at day 30. No significant difference was found in 30-day survival between manual and mechanical chest compression.

Acute lumbar radiculopathy (sciatica) is a commonly encountered clinical problem. Both primary care providers and pain medicine specialists are often called upon to manage these patients. The use of short courses of oral steroids has risen in popularity as this treatment is rapid, inexpensive, and relatively low risk. In a group of 269 patients suffering from sciatica for 3 months or less, patients were provided a 15-day tapering course of prednisone or placebo. At 3 weeks after the initiation of treatment the prednisone-treated group showed a small but greater reduction in Oswestry Disability Index scores (6.4 points, P = 0.006), the primary outcome, as compared with those receiving placebo. Secondary analyses showed no differences in pain scores at 3 weeks, and no differences in Oswestry Disability Index scores, pain scores, or surgery rates at 52 weeks. It appears that oral steroids may have a modest early effect on disability from acute sciatica, but confer little effect on pain or other outcomes in the longer term.

Physician fatigue and transitions of care have been implicated in adverse patient care events. Duty hour restrictions attempt to address fatigue but they may be offset by increased transitions of care. This randomized controlled trial looked at the effect of three resident intensive care unit schedules on adverse events and trainee fatigue. Anesthesia, medicine, and surgery residents were randomized to 12-, 16-, and 24-h intensive care unit shifts. The primary outcomes were adverse events and resident sleepiness. The study found no differences in adverse patient events or in overall resident fatigue. However, familiarity with the patient’s history was reduced with 12-h shifts. This study may have significant implications for anesthesia residents and critical care fellows by adding to the emerging data that shorter shifts may not necessarily result in increased patient safety or reduced trainee fatigue.