Clinical Adult Literature Updates from July 2012

Clinical Predictors of Apnoea-Hypopnoea During Propofol Sedation in Patients Undergoing Spinal Anaesthesia

This study assessed the relationship between the occurrence of apnoea-hypopnoea during propofol sedation for spinal anaesthesia and two different predictive tests of sleep apnoea: the STOP-Bang score (snoring while sleeping, daytime tiredness, observed breathing stoppages, high blood pressure-body mass index, age, neck circumference, gender); and the obstructive sleep apnoea (OSA) score. Both assessment tools have some predictive value for the occurrence of apnoea-hypopnoea during propofol sedation in patients undergoing spinal anaesthesia.

Obesity Hypoventilation Syndrome: A Review of Epidemiology, Pathophysiology, and Perioperative Considerations

Obesity hypoventilation syndrome (OHS) is defined by the triad of obesity, daytime hypoventilation, and sleep-disordered breathing without an alternative neuromuscular, mechanical, or metabolic cause of hypoventilation. It is a disease entity distinct from simple obesity and obstructive sleep apnea. OHS is often undiagnosed but its prevalence is estimated to be 10–20% in obese patients with obstructive sleep apnea and 0.15–0.3% in the general adult population. Compared with eucapnic obese patients, those with OHS present with severe upper airway obstruction, restrictive chest physiology, blunted central respiratory drive, pulmonary hypertension, and increased mortality.

Active Emergence from Propofol General Anesthesia is Induced by Methylphenidate

In this study, Chemali et al. demonstrate in rats that methylphenidate (Ritalin) not only decreases time to emergence after a single bolus of propofol, but also induces emergence during continuous propofol general anesthesia. These findings suggest that methylphenidate may be a useful arousal-promoting agent for patients oversedated with propofol.

Intramuscular Dexmedetomidine: An Effective Route of Sedation Preserves Background Activity for Pediatric Electroencephalograms

This article studies the administration of dexmedetomidine through IM route, as an efficacious drug that preserves background EEG activity to provide safe and effective sedation for EEG studies.

The EEG Signal: A Window on the Cortical Brain Activity

This review presents the main features of EEG, in adults and children, during the awake state and during sleep and also updates how anesthetic drugs(particularly hypnotics) influence the EEG signal, and how the main available monitors analyze these drug-induced modifications.

Mechanisms Mediating Effects of Nitric Oxide on Perifornical Lateral Hypothalamic Neurons

Nitric oxide is a gaseous neurotransmitter that has been implicated in the regulation of sleep. In this study the authors investigated contributions of adenosinergic, GABAergic, and sGC-cGMP signaling mechanisms in mediating nitrergic influences on a major wake-promoting structure, the perifornical-lateral hypothalamic area neurons.

Disrupted Sleep Without Sleep Curtailment Induces Sleepiness and Cognitive Dysfunction Via the Tumor Necrosis Factor-Alpha Pathway

This study demonstrates the activation of inflammatory mechanisms, more specifically TNF-alpha-dependent pathways after frequent sleep arousals.

National In-Hospital Morbidity and Mortality Trends After Lumbar Fusion Surgery Between 1998 and 2008

Studying trends in perioperative outcomes in spine surgical patients the authors found that mean patient age and comorbidity burden increased along with significant increases in peri-operative complications including pulmonary and cardiac. These trends highlight the need for appropriate peri-operative services to optimize outcomes in an increasingly morbid and older population of patients undergoing lumbar fusion.

Utilization of Critical Care Services Among Patients Undergoing Total Hip and Knee Arthroplasty: Epidemiology and Risk Factors

The authors sought to identify the incidence and risk factors for the use of critical care services among orthopedic patients and compare the characteristics and outcomes of patients who require critical care services to those who do not. The presence of pulmonary compromise was associated with the highest odds for the use of critical care services (OR 18.44 (16.55, 20.55)).

Pulmonary Hypertension: An Important Predictor of Outcomes in Patients Undergoing Non-Cardiac Surgery

The authors of this article report on perioperative outcomes in a large cohort of patients undergoing non-cardiac surgery, comparing those with and without pulmonary hypertension. They conclude, that in addition to the traditionally known risk factors for outcomes such as coronary artery disease, diabetes mellitus, chronic renal insufficiency, and American Society of Anesthesiology class, the presence of underlying pulmonary hypertension can have a significant negative impact on perioperative outcomes.