THIS MONTH IN Anesthesiology

Abstract

Guidelines for the use of transesophageal echocardiography are updated.A novel fiberoptic technique to guide epidural needle placement is described. See the accompanying Editorial View on page 1073 Treatment of adrenal insufficiency in brain-dead patients is evaluated.A population-based study that provides a detailed overview of postoperative mortality for several surgeries is reviewed. See the accompanying Editorial View on page 1065 Changes in α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor trafficking in persistent pain are reviewed.Approximately 3,500 blood transfusions are given to intensive care unit (ICU) patients daily in the United States. Although there are no reliable predictors of transfusion requirements, ICU patients with functional iron deficiency may be at higher risk for developing anemia requiring blood transfusion. A prospective cohort study of 62 patients was conducted to assess the effects of low reticulocyte hemoglobin content (CHr <29 pg) on transfusion rates. The overall transfusion rate was 22.6%; the rate was 39.1% versus 12.8%, in low-CHr and normal-CHr patients, respectively. Patients with low CHr (37%) had a longer median ICU stay (8 vs. 5 days), were more likely to have sepsis, and were more prone to acute renal failure (39% vs. 13%) and ICU-acquired infection (30% vs. 10%) compared with patients with normal CHr. Low CHr was significantly associated with transfusion regardless of age, severity of illness, trauma, or hemoglobin level. Low CHr is common at ICU admission and was associated with higher transfusion requirements.Despite evidence for implicit memory, which may result in changes in behavior during anesthesia in adults, evidence in children is less clear. This randomized, double-blind controlled trial in children aged 5 to 12 yr (N = 312) used perceptual priming (via a degraded auditory stimulus recognition task) to detect potential development of implicit memory after anesthesia. Either a sheep sound or white noise was played continuously through headphones during general anesthesia. On recovery, children were played a sheep sound degraded by a white noise mask that progressively decreased over 60 s, with the outcome being the time taken to correctly recognize the sheep sound. There was little evidence that exposure to a sheep sound during anesthesia was associated with postoperative time to recognition of a degraded sheep sound. This study presents additional support that implicit memory formation during routine anesthesia is not a clinical concern for pediatric anesthesiologists. See the accompanying Editorial View on page 1063 Mortality after cardiac surgery may be associated with patient-related and surgery-related variables such as persistent hypotension and the cumulative duration of low processed electroencephalogram-based bispectral index (BIS). This prospective, randomized study assessed the relationships among cumulative duration of low BIS (<45), intermediate-term mortality, and anesthetic dose in patients (N = 460) who underwent cardiac surgery during a 1-yr period. During a median follow-up of 3 yr, 17.8% of patients died. There was no statistically significant difference in end-tidal anesthetic gas concentrations between patients who died and those who survived. However, cumulative duration of low BIS was independently associated with intermediate-term mortality with a 29% increased risk of death for every cumulative hour spent with a BIS less than 45. These data suggest that intermediate-term mortality after cardiac surgery was not causally related to excessive anesthetic dose. See the accompanying Editorial View on page 1070