Key Papers from the Most Recent Literature Relevant to Anesthesiologists
The interface between delirium and dementia in elderly adults. Lancet Neurol 2015; 14:823–32.
Delirium and dementia are two of the most common causes of cognitive impairment in older populations, yet their interrelation remains poorly understood. This issue is highly relevant to the perioperative and intensive care unit settings. This robustly argued, very clearly illustrated review proposes the rationale for delirium to likely interface with dementia on many levels: it is a marker of vulnerability of the brain, it unmasks unrecognized dementia, it mediates the effects of noxious insults, and itself leads to permanent neuronal damage and dementia. Study of the relation between delirium and dementia raises numerous challenges, highlighting the barriers to investigation of this important area.
Lung-function trajectories leading to chronic obstructive pulmonary disease. N Engl J Med 2015; 373:111–22.
Recent effort has focused on predicting postoperative risk in surgical patients by using preoperative scoring and intraoperative ventilation modalities. Patients presenting with chronic obstructive pulmonary disease (COPD) are common and this disease has a significant impact on the conduct of anesthesia. This study included 657 patients from three independent cohorts and followed the decline of forced expiratory volume (FEV1) COPD status over time. Among 657 persons who had an FEV1 of less than 80% of the predicted value before 40 yr of age, 174 (26%) had COPD after 22 yr of observation, whereas among 2,207 persons who had a baseline FEV1 of at least 80% of the predicted value before 40 yr of age, 158 (7%) had COPD after 22 yr of observation (P < 0.001). These results suggest that the classic trajectory of an accelerated decline in FEV1 from a normal level is not an obligate feature of COPD and that a substantial proportion of the persons in whom COPD develops have a low FEV1 level in early adulthood.
Cost-effectiveness of 10-year risk thresholds for initiation of statin therapy for primary prevention of cardiovascular disease. JAMA 2015; 314:142–50.
Anesthesiologists care for thousands of patients routinely treated with statins, most of them for secondary prevention. This study was designed to estimate the cost-effectiveness of various 10-yr atherosclerotic cardiovascular disease (ASCVD) risk thresholds that could be used in the American College of Cardiology and the American Heart Association cholesterol treatment guidelines for primary cardiovascular prevention. In this simulation model of U.S. adults aged 45 to 70 yr, the main outcome measure was estimated ASCVD events prevented and incremental costs per quality-adjusted life-year gained. The current 10-yr ASCVD risk threshold (≥ 7.5% risk threshold) used in the American College of Cardiology and the American Heart Association cholesterol treatment guidelines has an acceptable cost-effectiveness profile ($37,000/quality of life-year [QALY] gained). However, more lenient ASCVD thresholds for treatment, for example, 4.0% or 3% risk threshold, would avert significantly more adverse cardiovascular disease events at significantly greater cost ($100,000/QALY gained and $150,000/QALY gained, respectively). The optimal ASCVD threshold was sensitive to patient preferences for taking a pill daily, changes to statin price, and the risk of statin-induced diabetes.
Restrictive versus liberal blood transfusion for acute upper gastrointestinal bleeding (TRIGGER): A pragmatic, open-label, cluster randomised feasibility trial. Lancet 2015; 386:137–44.
Data obtained from a single center trial suggested reduced mortality with restrictive erythrocyte transfusion. We aimed to assess whether a multicenter, unblinded, cluster randomized trial is a feasible method to substantiate or refute this finding. Restrictive (liberal, respectively) transfusion was defined when hemoglobin level less than 8 g/dl (10 g/dl, respectively). The trial enrolled 936 patients from six United Kingdom hospitals, led to rapid recruitment, high protocol adherence, separation in degree of anemia between groups, and nonsignificant reduction in erythrocyte transfusion in the restrictive policy. No significant difference was found between groups in major clinical outcomes. A large cluster randomized trial to assess the effectiveness of transfusion strategies for acute upper gastrointestinal bleeding is both feasible and essential before clinical practice guidelines change to recommend restrictive transfusion for all patients with acute upper gastrointestinal bleeding.
Intraoperative protective mechanical ventilation and risk of postoperative respiratory complications: Hospital based registry study. BMJ; 2015; 351:h3646.
Despite the results of the IMPROVE and PROVILHO trials, it is unclear if patients with normal lungs undergoing brief intraoperative ventilation are vulnerable to ventilator-induced lung injury. In this registry study, the authors enrolled 69,265 consecutive patients undergoing noncardiac surgery between January 2007 and August 2014 and examined the impact of protective ventilation (defined as a median positive end-expiratory pressure of 5 cm H2O or more, a median tidal volume of less than 10 ml/kg of predicted body weight, and a median plateau pressure of less than 30 cm H2O) on major postoperative respiratory complications measured by a composite score. It was found that protective ventilation reduced the risk of postoperative respiratory complications in a large group of patients undergoing a variety of surgical procedures. A positive end-expiratory pressure greater than 5 cm H2O and a plateau pressure of 16 cm H2O or less were identified as protective mechanical ventilator settings. These data confirm and extend the benefits of intraoperative protective lung ventilation in a large panel of surgical patients.
Association of bystander and first-responder intervention with survival after out-of-hospital cardiac arrest in North Carolina, 2010–2013. JAMA 2015; 314:255–64.
Resuscitation of out-of-hospital cardiac arrest remains a topic of intense investigation, with particular focus on improving the first chain of resuscitation. This article provides a clear demonstration of the marked efficacy of initiating cardiac massage and defibrillation as early as possible by bystanders (those who assist to the cardiac arrest) and first responders (the first life-support rescuers arriving on scene). Two main results were obtained from this 4,961-patient cohort. First, following a statewide educational intervention on resuscitation training, the proportion of patients receiving bystander-initiated cardiopulmonary resuscitation and defibrillation by first responders increased and was associated with greater likelihood of survival. Second, bystander-initiated cardiopulmonary resuscitation was associated with greater likelihood of survival with favorable neurologic outcome. Improving the reactivity of the first chain of cardiac arrest resuscitation should be a universal priority on this area of investigation, since it has proven efficacy on outcome.
Development and preliminary validation of an integrated efficacy–tolerability composite measure for the evaluation of analgesics. Pain 2015; 156:1357–65.
For good reasons clinical trials focus on the efficacy of treatments, but how do we factor tolerability into our evaluations? To this point we have generally attempted to evaluate tolerability by looking at separate and sometimes difficult-to-interpret tables of adverse events. In their innovative study Katz et al. describe a novel measure termed the “efficacy–tolerability composite.” This measure combines information related to effect size, for example, percent pain reduction, and the frequency of adverse events. This approach was applied to data from a previous trial comparing the efficacy and tolerability of oxycodone and tapentadol in the treatment of low back pain. The investigators identified combinations of efficacy–tolerability parameters that correlated well with the patients’ perception of change and which had the ability to discriminate between the two treatments. In this case tapentadol had similar efficacy to oxycodone, but was better tolerated. While the authors emphasized that this was a preliminary validation, including this type of efficacy–tolerability composite measure may aid our ability to compare alternative treatments based on two key outcomes, efficacy and tolerability.
Induction of general anesthesia is in the eye of the beholder—objective feedback through a wearable camera. J Grad Med Educ 2015; 7:268–9. An innovative approach to avoid reinventing the wheel: The anesthesia education toolbox. J Grad Med Educ 2015; 7:270–1.
The June 2015 issue of the Journal of Graduate Medical Education features a “New Ideas” section “… showcasing novel and implemented innovative initiatives in graduate medical education.… almost 100 submissions were reviewed … yield[ing] 15 innovative approaches with the potential to advance the GME [graduate medical education] community’s deliberations about innovation and improvement.” Two of the 15 published educational New Ideas are specific to anesthesiology. Woodworth and colleagues describe how they parlayed the definition of a regional anesthesia curriculum for five departments of anesthesiology into a program supporting “… 30 anesthesiology residency programs and more than 2000 residents, fellows, and faculty.” Kamath and colleagues describe how use of a head-mounted video camera can capture the complete procedure that upon debriefing review is robust fodder for education.