Anesthesia Literature Review

J. Lance Lichtor, M.D., Editor 

In this randomized study, transfusion was set at less than 8 g hemoglobin (restrictive) or less than 10 g hemoglobin (liberal); an opportunity for transfusion based on symptoms of anemia was included. Death or inability to walk without human assistance 60 days after surgery was not different between the liberal and restrictive transfusion groups (see fig. 1). Other complications were similar between groups. If the findings of the study were followed more broadly, the risk of exposure to blood and the cost of transfusion could be greatly reduced.

This study examined intraoperative blood transfusion and surgical morbidity and mortality. These data were retrospectively generated from one million patients who underwent noncardiac surgery. Transfusion with even one unit of packed erythrocytes was associated with significantly increased mortality, pulmonary complications, renal dysfunction, wound problems, sepsis, and longer hospitalizations (see fig. 2). These findings are similar to other studies suggesting adverse events in patients who underwent transfusion.

In this study, 16 patients were determined to be in a vegetative state using clinical criteria. It was noted that for three patients, distinct commands could generate reproducible electroencephalography responses; yet, behaviorally the patients were not responsive. The authors propose that this test could be used to confirm that patients are in a vegetative state and identify those who may have residual cognitive function and awareness.

In this study of 298 women (most of whom were white) with a mean age of 82 yr, sleep-disordered breathing was shown to be associated with an increased risk of cognitive impairment 5 yr later (see fig. 3). Furthermore, hypoxia was found to further associate with cognitive impairment, suggesting that prolonged exposure to intermittent hypoxia may contribute to cognitive decline. This study has implications for perioperative cognitive impairment.

Jean Mantz, M.D., Ph.D., Editor 

This prospective cohort study challenges the common view that age is not a criterion per se  to admit critically injured patients into the intensive care unit (ICU). Requests for admissions were evaluated for 11 ICUs over a 2-yr period. Surprisingly, a greater survival benefit was present in older patients but not in younger patients admitted to the ICU (see fig. 4). Although these findings cannot be extrapolated as a general rule, these data suggest that intensivists should revise their triage practices for elderly patients, particularly accepting those appearing “well.”

This study highlights a sensitive, somewhat hidden, but very frequent situation occurring with caregivers working in intensive care units (ICUs); that is, determining appropriateness of care. The feeling of providing disproportionately excessive care was the most frequent report. Perceptions of inappropriate care were inversely associated with factors indicating good teamwork, which calls for urgent consideration of good teamwork in ICUs in these countries. Inappropriateness of care was associated with increased likelihood to leave a job.

This study provides new insight into the outcome of patients with acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). One hundred twenty-two patients requiring bronchoalveolar lavage were enrolled. Cell counts were compared between patients with ALI/ARDS who survived or did not survive (see fig. 5). A fibrocyte percentage more than 6% was independently associated with mortality. The use of this new biomarker could help stratify ALI/ARDS patients at high risk of poor outcome and to increase our understanding of the mechanisms of fibrocyte proliferation during injury and repair in ALI/ARDS.

Timothy J. Brennan, Ph.D., M.D., Editor 

The mechanisms by which opioids produce itch, especially spinal opioids, are not well understood. These authors previously identified an itch-specific pathway in the dorsal horn of the spinal cord in mice. These itch-transmitting dorsal horn neurons express a gastrin-releasing peptide receptor. In this report, the authors demonstrate that a μ-opioid receptor (MOR) isoform, MOR1D, is required for spinal morphine induced scratching; yet, the MOR1D is not required for analgesia by spinal morphine. Surprisingly, the MOR1D receptor combines with the gastrin- releasing peptide receptor to signal itch by opioids. This study suggests a mechanism whereby itch can be reduced without affecting analgesia.

Preoperative predictors of acute postoperative pain vary among different surgeries. In this study, younger age, presence of presurgical pain, presence of nonpelvic pain, pain catastrophizing, and presurgical anxiety together strongly predict moderate to severe postoperative pain (see fig. 6). Anxiety appeared to contribute to pain catastrophizing. The authors propose that for patients undergoing hysterectomy, brief preoperative psychologic interventions be used to reduce the effect of anxiety and catastrophizing, which are modifiable risk factors, on moderate to severe acute postoperative pain.