This Month in Anesthesiology

The Hypotension Prediction Index was developed to predict hypotension, a mean arterial pressure (MAP) below 65 mmHg for at least 1 min, up to 15 min in advance based on characteristics of the arterial waveform. The hypothesis that the Hypotension Prediction Index and MAP-based predictions are equally effective in predicting hypotension was tested in a prospective observational study of 100 moderate- to high-risk noncardiac surgery patients. The study analyzed 68,583 data points, 2,061 (3.0%) of which were defined as hypotensive and grouped into 231 hypotensive events. The predictive performances of the Hypotension Prediction Index and the concurrent MAP within 1 to 5 min before hypotension occurred assessed using areas under the receiver operating characteristic curve were virtually identical; the area under the curve (95% CI) for the Hypotension Prediction Index was 0.89 (0.88 to 0.89) and that for MAP was 0.88 (0.88 to 0.89). When predicting hypotension within 5 min, the Hypotension Prediction Index had a sensitivity of 72.4%, a specificity of 89.9%, and a positive predictive value of 31.9%. The MAP threshold set at 72 mmHg had a sensitivity of 72.6%, a specificity of 90.3%, and a positive predictive value of 32.9%. See the accompanying Editorial on page 421.The Hypotension Prediction Index algorithm was developed to detect early hemodynamic instability that may lead to hypotensive events, a mean arterial pressure (MAP) less than 65 mmHg for at least 1 min. The original validation of the Hypotension Prediction Index used a backward (case control) methodology, which identified a hypotensive event before looking backward in time to see whether a variable predicted it. Because such an analysis had been suggested to be biased and does not represent how such data are used, the present study compared the original backward validation with a forward (cohort) methodology using data from nine previously reported studies. The analyses included 4,152,124 data points from 2,022 patients who experienced 24,654 hypotensive events. The predictive performance of the backward analysis assessed using area under the receiver operating characteristic curve (95% CI) was 0.957 (0.947 to 0.964) and that for the forward analysis (5 min in advance) was 0.923 (0.912 to 0.933). The authors concluded that although the area under the receiver operating characteristic curve for the forward methodology was less than that for the backward methodology, the utility of the Hypotension Prediction Index was still excellent. See the accompanying Editorial on page 421.Posttonsillectomy pain is common in children and adolescents and optimal posttonsillectomy pain control remains elusive. This randomized, double-blind, initial dose-escalation study of 60 children and adolescents undergoing tonsillectomy tested the hypothesis that single-dose intraoperative methadone would result in less total opioid use in the first 7 days after surgery compared with intraoperative fentanyl administered at the discretion of the practitioner. The treatment groups were balanced by age. The initial cohort of 20 patients randomized to receive methadone received 0.1 mg/kg age-ideal body weight and the second methadone cohort received 0.15 mg/kg age-ideal body weight. The primary outcome, total 7-day (including postanesthesia care unit) postoperative opioid use, was analyzed as oral morphine equivalents per kilogram (actual body weight, OME/kg). Median (interquartile range) total 7-day opioid use in the control group was 1.5 (1.2 to 2.1) OME/kg, that in the methadone 0.1 mg/kg group was 0.9 (0.1 to 1.4) OME/kg (P = 0.045 compared to control), and that in the methadone 0.15 mg/kg group was 0.5 (0 to 1.4) OME/kg (P = 0.023 compared to control). See the accompanying Editorial on page 425.Children often experience emergence delirium after sevoflurane anesthesia. The hypothesis that a continuous infusion or a bolus dose of remimazolam could reduce the incidence of emergence delirium in children after laparoscopic surgery under sevoflurane anesthesia was tested in a randomized controlled study of 119 children aged 1 to 6 yr. Laparoscopic surgery was studied to minimize the effect of pain on the emergence delirium diagnosis. Patients were randomized to receive a 1 mg · kg–1 · h–1 remimazolam infusion throughout the procedure, a 0.2 mg · kg–1 remimazolam bolus at the start of wound closure, or a saline infusion and a saline bolus at wound closure. Emergence delirium was assessed using the Pediatric Anesthesia Emergence Delirium (PAED) scale and postoperative pain was measured using Face, Legs, Activity, Cry, Consolability (FLACC) scores. Children with an initial PAED score of 10 or more and a FLACC score of 4 or more were reassessed for emergence delirium 5 min after administration of an analgesic to minimize the potential influence of pain on emergence delirium assessment. Emergence delirium was observed in 14 of 40 (35%) control patients, in 2 of 40 (5%) patients receiving a remimazolam infusion (risk ratio [95% CI], 0.14 [0.04 to 0.59]), and in 3 of 39 (7.7%) patients receiving a remimazolam bolus (0.22 [0.07 to 0.71]). See the accompanying Editorial on page 434.Cardiac troponins are considered the gold standard for diagnosing myocardial injury, and N-terminal pro–B-type natriuretic peptide (NT-proBNP) is a cardiac biomarker widely used to assess cardiac dysfunction. The hypothesis that preoperative concentrations of both NT-proBNP and high-sensitivity cardiac troponin T (hs-cTnT) would be associated with the risk of cardiovascular events after major noncardiac surgery was tested in a prospective cohort study of 2,833 patients aged 45 yr or older. Eligible participants had either a history of cardiovascular disease or at least two risk factors for postoperative cardiovascular complications. The primary outcome, a collapsed composite of any cardiovascular events within 30 days after surgery, was experienced by 435 of 2,820 patients (15.4%). The area under the receiver operating characteristic curve (95% CI) of the baseline model for predicting the primary outcome containing only clinical variables was 0.728 (0.702 to 0.754). When preoperative concentrations of NT-proBNP or hs-cTnT were added to the baseline model, the area under the curve increased by 0.028 and 0.029, respectively. When concentrations of both biomarkers were added to the model, the area under the curve was 0.770 (0.747 to 0.793). See the accompanying Editorial on page 428.Hemorrhagic shock (HS) and rhabdomyolysis (RM) have been reported to be the two most important factors associated with posttraumatic acute kidney injury (AKI). The goal of this study was to determine the combined effect of HS and RM by studying the effect of HS and RM, alone or in combination, on systemic hemodynamics and renal microcirculatory perfusion, oxygenation, function, and morphology in an experimental porcine model. Forty-seven female pigs were randomly divided into five groups: sham, RM, HS, HS with moderate RM, and HS with severe RM. Blood pressure–controlled HS was induced by exsanguination followed by fluid resuscitation with crystalloids and, after resuscitation, transfusion of the shed blood. RM was induced by an intramuscular injection of glycerol. Although the primary outcome was creatinine clearance on day 2, the high mortality in the RM and HS with RM groups precluded comparison of data at day 2. RM exacerbated the HS-induced impairment of renal perfusion, oxygenation, and function. Unlike HS alone, fluid resuscitation failed to restore renal perfusion, oxygenation, and function when RM and HS were combined.Maintaining appropriate hemostasis requires a balanced relationship between coagulation and fibrinolysis and is essential for overall homeostasis. When this equilibrium is lost, the clinically relevant consequences include coagulopathies with different degrees of severity, potentially evolving to overt disseminated intravascular coagulation. Disseminated intravascular coagulation is characterized by bleeding or thrombosis and organ dysfunction resulting from microcirculatory disturbances. Although disseminated intravascular coagulation is primarily the result of coagulation system (over)activation, additional mechanisms contribute, including dysfunction of physiologic anticoagulation, altered fibrinolysis, and thromboinflammation. This Clinical Focus Review examines the significance of hemostatic disequilibrium in the pathophysiology of disseminated intravascular coagulation and associated underlying conditions typically encountered in clinical practice. It also explores strategies for disseminated intravascular coagulation diagnosis, treatment, and restoration of the lost balance in sepsis, trauma, and obstetrics, clinical settings frequently complicated by disseminated intravascular coagulation.This review considers the American Society of Anesthesiologists (ASA) Statement on Ethical Guidelines for the Anesthesia Care of Patients with Do-Not-Resuscitate Orders in a contemporary context and provides practical guidance for the delivery of ethically appropriate, goal-concordant care by anesthesiologists. It begins by reviewing the relevance and limitations of nonmaleficence and respect for autonomy when applied to ethically informed decision-making regarding perioperative cardiopulmonary resuscitation. Several aspects of ASA guidelines for care of patients with do-not-resuscitate orders or other directives limiting treatment are clarified based on the discussion of ethical principles and their application. Key elements of ethically informed decision-making regarding perioperative cardiopulmonary resuscitation are then highlighted. The review concludes that after establishing the clinical context for the planned procedure, learning about the rationale for a patient’s existing code status, and eliciting the patient’s priorities and concerns, it is appropriate to summarize the conversation and offer plans for interventions that have been deemed appropriate under the circumstances in collaboration with the patient’s surgeon. See the accompanying Editorial on page 440.