Benjamin Scott

Circadian Rhythms in Anesthesia and Critical Care Medicine Potential Importance of Circadian Disruptions

The rotation of the earth and associated alternating cycles of light and dark—the basis of our circadian rhythms—are fundamental to human biology and culture. However, it was not until 1971 that researchers first began to describe the molecular mechanisms for the circadian system. During the past few years, groundbreaking research has revealed a multitude of circadian genes affecting a variety of clinical diseases, including diabetes, obesity, sepsis, cardiac ischemia, and sudden cardiac death. Anesthesiologists, in the operating room and intensive care units, manage these diseases on a daily basis as they significantly affect patient outcomes. Intriguingly, sedatives, anesthetics, and the intensive care unit environment have all been shown to disrupt the circadian system in patients. In the current review, we will discuss how newly acquired knowledge of circadian rhythms could lead to changes in clinical practice and new therapeutic concepts.

The impact of sedation protocols on outcomes in critical illness.

Critically ill patients often require pharmacologic sedation to treat pain, agitation, and delirium or to tolerate mechanical ventilation and invasive procedures (1). Over the last several decades, our understanding of medications commonly administered for sedation in the critically ill has increased and we now appreciate both the short and long-term consequences of prolonged exposure to these agents. In fact, the Society of Critical Care Medicine recently revised its sedation guidelines based on emerging evidence that certain sedation practices may influence outcomes in critical illness (2). For example, it has become quite clear that prolonged exposure to benzodiazepines and, to a lesser extent opiates, contributes to the development of delirium, while the use of dexmedetomidine might decrease the risk. However, it would be premature to suggest that we currently know enough to protocolize “optimal” sedation algorithms. Despite this recent interest in dexmedetomidine as a “delirium sparing” sedative-hypnotic, a recent meta-analysis concluded that no definitive conclusions on the use of dexmedetomidine can be drawn yet and more clinical trials seem warranted (3). In any case, delirium is associated with increased mortality, prolonged stay on the intensive care unit (ICU) and the development of post ICU cognitive impairment, and the search for new strategies to prevent or treat delirium is currently an area of intense investigation (4).

Health implications of disrupted circadian rhythms and the potential for daylight as therapy.

For many thousands of years, the sun was our only source of light, and human behavior followed a natural day-night cycle. This milieu began to change approximately 150 years ago with the invention of incandescent lighting. Electric lighting disrupted our behavioral dependence on the day-night cycles of the sun, and facilitated alterations in our circadian sleep-wake cycles. Recent research has begun to identify the physiologic consequences of unnatural light exposure and subsequently altered circadian rhythms.1 In this paper, we review the molecular basis of circadian rhythms and discuss the established connection between disrupted circadian rhythms and clinical disease. We also explore the concept of daylight as therapy to restore disrupted circadian rhythms and improve clinical outcomes.

Heated humidified high-flow nasal cannula oxygen after thoracic surgery — A randomized prospective clinical pilot trial

Background Thoracic surgery patients are at high‐risk for adverse pulmonary outcomes. Heated humidified high‐flow nasal cannula oxygen (HHFNC O2) may decrease such events. We hypothesized that patients randomized to prophylactic HHFNC O2 would develop fewer pulmonary complications compared to conventional O2 therapy. Methods and patients Fifty‐one patients were randomized to HHFNC O2 vs. conventional O2. The primary outcome was a composite of postoperative pulmonary complications. Secondary outcomes included oxygenation and length of stay. Continuous variables were compared with t‐test or Mann‐Whitney‐U test, categorical variables with Fishers Exact test. Results There were no differences in postoperative pulmonary complications based on intention to treat [two in HHFNC O2 (n = 25), two in control (n = 26), p = 0.680], and after exclusion of patients who discontinued HHFNC O2 early [one in HHFNC O2 (n = 18), two in control (n = 26), p = 0.638]. Discomfort from HHFNC O2 occurred in 11/25 (44%); 7/25 (28%) discontinued treatment. Conclusions Pulmonary complications were rare after thoracic surgery. Although HHFNC O2 did not convey significant benefits, these results need to be interpreted with caution, as our study was likely underpowered to detect a reduction in pulmonary complications. High rates of patient‐reported discomfort with HHFNC O2 need to be considered in clinical practice and future trials. HighlightsPulmonary complications were rare after thoracic surgery.Patient‐reported discomfort was more frequent with the use of HHFNC O2.This pilot study did not indicate a beneficial effect of prophylactic HHFNC O2.Larger samples are necessary to definitively ascertain benefits of HHFNC O2.

Pneumomediastinum and Bilateral Pneumothoraces Causing Respiratory Failure after Thyroid Surgery

We report the first case of severe respiratory failure after thyroid surgery requiring venovenous extracorporeal membrane oxygenation (vvECMO). The patient was a 41-year-old woman with metastatic thyroid cancer. She underwent thyroidectomy, including left lateral and bilateral central neck dissection. During surgery, the patient developed pneumomediastinum with bilateral pneumothoraces. Despite early treatment with bilateral chest tubes and no evidence of a tracheal perforation, the patient developed severe respiratory failure after extubation on the intensive care unit. Because pneumothorax and pneumomediastinum might be more common than reported, and considering increasing cases of thyroid surgery, staff should remain vigilant of pulmonary complications after thyroid surgery.

130: CLINICAL IMPACT OF AN EDUCATIONAL COURSE FOR HOSPITAL RAPID RESPONSE TEAMS

Introduction: Throughout the country, patients are increasingly likely to require critical care intervention. Numerous studies have shown that early recognition and intervention can improve outcomes in hospitalized patients. Many hospitals are utilizing rapid response teams (RRTs) to help identify a