Anesthesia Literature Review

A retrospective study compared two groups of patients who had undergone major noncardiac surgery and who had undergone a polysomnography study for assessing obstructive sleep apnea (OSA) syndrome within 3 yr. The patients with an apnea-hypopnea index of 5 or more (282) were defined as OSA, and the remaining patients (189) served as the control group. Both groups were adjusted and classified according to a propensity score. The presence of OSA syndrome was associated with a higher risk of hypoxemia, postoperative complications, and longer hospital stay (fig. 1). The severity of OSA was not associated with a greater incidence of complications.

Severe traumatic brain injury is a catastrophic event with devastating social, familial, and economic consequences. The efficacy of amantadine in improving disabilities in patients with posttraumatic disorders of consciousness has been suggested in previous pilot studies. In this prospective, randomized, blinded, and placebo-controlled trial, the authors demonstrate that amantadine, in doses up to 150 mg daily for 4 weeks, significantly accelerates the rate of functional recovery at 6 weeks versus  placebo (fig. 2). No significant difference in adverse effects was found between the amantadine and placebo groups. These results suggest that amantadine may be useful in improving disability 4 weeks after severe traumatic brain injury. Later, long-term benefit has not yet been proven.

Postoperative pulmonary complications increase morbidity, length of stay, and costs after surgery. This large prospective cohort study evaluated predictors of postoperative pulmonary complications after liver resection. Five independent predictive factors were identified (table 1): prolonged surgery, presence of a nasogastric tube, intraoperative blood transfusion, diabetes mellitus, and transverse subcostal bilateral muscle-cutting incision. These findings offer simple and modifiable targets to reduce the occurrence of pulmonary complications after liver resection.

Diastolic dysfunction is associated with congestive heart failure symptoms, even in patients with preserved left ventricular function. Whether worsening of diastolic dysfunction is associated with worse prognosis is unknown. A retrospective cohort of 1,065 consecutive outpatients undergoing echocardiography was followed for 6–24 months. Progressive worsening of left ventricular ejection fraction of less than 55%, together with any grade of deterioration of diastolic dysfunction, was an independent predictor of mortality. Left ventricular dysfunction is present in many surgical patients preparing for anesthesia and surgery. Identification and optimization of these patients in the perioperative period is needed.

Some clinicians use laryngoscopic exams to define the appropriate tracheal extubation time in patients with airway edema and potential postextubation failure. The authors present a series of cases in which video laryngoscopy-derived images were captured on cell phone cameras. The images were used to longitudinally evaluate the retroglossal and laryngeal airway anatomy. The images were copied into the patients' electronic acute care document, to improve communication at shift handover.

Early enteral nutrition improves outcomes in patients in the intensive care unit. There is a controversy, however, as to whether mechanically ventilated patients with ARDS would benefit from early full enteral or lower-volume trophic feeding. The EDEN randomized trial found no significant difference in the number of ventilator-free days between patients who were fed either with full (1,300 kcal/day) or trophic (lower-volume; 400 kcal/day) enteral support for the initial 6 days. There was no difference in infectious complications, mortality, or delay to hospital discharge between the groups (fig. 3). Full enteral feeding was associated with less gastrointestinal intolerance. These results do not support a full enteral feeding strategy in this patient subpopulation.

In an excellent “mouse to man story,” the authors previously identified the β2-adrenergic receptor as being important for the development of opioid-induced hyperalgesia using an “in silica” genetic screening study. In the current human volunteer trial, the authors conducted a double-blind, randomized crossover trial in which they evaluated the area of secondary hyperalgesia induced by remifentanil in the presence and absence of the β-blocker, propranolol. The increase in secondary hyperalgesia was significantly blocked by propranolol (fig. 4). β2-adrenergic blockade might be useful for reducing opioid hyperalgesia when high-dose opioids are used during surgery. This study also provides proof of principle for the ability to translate “in silico” screening techniques in animal models.

Only 30–80% of patients experience pain relief from topical lidocaine (5%). The reasons for the lack of response in some patients are not known. In this blinded study of healthy volunteers, topical lidocaine (5%) induced thermal hypoesthesia and pinprick hypoalgesia but did not completely block these responses. These findings support that topical lidocaine has only a partial blocking effect of A-δ and C fibers of unpredictable extent. The next question to address is whether patients with poor analgesic effect are precisely those with insufficient small-fiber block. This could favor strategies to improve efficacy of topical lidocaine in clinical practice.