High-Flow Nasal Oxygen Improves Safe Apnea Time in Morbidly Obese Patients Undergoing General Anesthesia: A Randomized Controlled Trial.

BACKGROUND: Morbidly obese patients undergoing general anesthesia are at risk of hypoxemia during anesthesia induction. High-flow nasal oxygenation use during anesthesia induction prolongs safe apnea time in nonobese surgical patients. The primary objective of our study was to compare safe apnea time, between patients given high-flow nasal oxygenation or conventional facemask oxygenation during anesthesia induction, in morbidly obese surgical patients. METHODS: Research ethics board approval was obtained. Elective surgical patients ≥18 years with body mass index ≥40 kg·m were included. Patients with severe comorbidity, gastric reflux disease, known difficult airway, or nasal obstruction were excluded. After obtaining informed consent patients were randomized. In the intervention (high-flow nasal oxygenation) group, preoxygenation was provided by 100% nasal oxygen for 3 minutes at 40 L·minute; in the control group, preoxygenation was delivered using a facemask with 100% oxygen, targeting end-tidal O2 >85%. Anesthesia was induced with propofol, remifentanil, and rocuronium. Bag-mask ventilation was not performed. At 2 minutes after rocuronium, videolaryngoscopy was performed. If the laryngoscopy grade was I or II, laryngoscope was left in place and the study was continued; if grade III or IV was observed, the patient was excluded from the study. During the apnea period, high-flow nasal oxygenation patients received nasal oxygen at 60 L·minute; control group patients received no supplemental oxygen. The primary outcome, safe apnea time, was reached when oxygen saturation measured by pulse oximetry (SpO2) fell to 95% or maximum 6 minutes of apnea. The patient was then intubated. T tests and χ analyses were used to compare groups. P < .05 was considered significant. RESULTS: Forty patients completed the study. Baseline parameters were comparable between groups. Safe apnea time was significantly longer (261.4 ± 77.7 vs 185.5 ± 52.9 seconds; mean difference [95% CI], 75.9 [33.3-118.5]; P = .001) and the minimum peri-intubation SpO2 was higher (91.0 ± 3.5 vs 88.0 ± 4.8; mean difference [95% CI], 3.1 [0.4-5.7]; P = .026) in the high-flow nasal oxygenation group compared to the control group. CONCLUSIONS: High-flow nasal oxygenation, compared to conventional oxygenation, provided a longer safe apnea time by 76 seconds (40%) and higher minimum SpO2 in morbidly obese patients during anesthesia induction. High-flow oxygenation use should be considered in morbidly obese surgical patients.

An update on preoperative assessment and preparation of surgical patients with obstructive sleep apnea.

PURPOSE OF REVIEW: There is a high prevalence of obstructive sleep apnea (OSA) in the surgical population, however, a significant proportion of patients are undiagnosed. The Society of Anesthesia and Sleep Medicine (SASM) has issued recent guidelines for preoperative assessment and preparation of patients with known or suspected OSA. The purpose of this review is to highlight key points in the new guidelines and explore the possibilities of different strategies in optimizing patients with OSA preoperatively. RECENT FINDINGS: Recent knowledge on phenotypes and endotypes has provided a better understanding of the disease and its underlying pathogenesis. Phenotypes refer to the predominant morphological characteristics of an individual whereas endotypes refer to the predominant underlying mechanism of the disease. Phenotypes and endotypes in OSA are heterogenous. Heterogeneity in the pathogenic mechanisms implies that opportunities other than the use of continuous positive airway pressure (CPAP) may exist to optimize or manage OSA patients preoperatively. SUMMARY: The prevalence of OSA in surgical patients is high. SASM has made recommendations in their published guidelines for the optimum preoperative preparation of patients with OSA. In the future, research may shift towards finding the underlying mechanism of OSA for targeted therapy.

Say what? Patients have poor immediate memory of major risks of interscalene block disclosed during the informed consent discussion.

BACKGROUND: Poor memory of disclosed risks can undermine informed consent and create medicolegal challenges. The extent to which patients remember the risks of peripheral nerve blockade following the informed consent discussion is unknown. This prospective cohort study evaluated patients' immediate memory of risks related to interscalene block (ISB) that were disclosed during the preoperative informed consent discussion. METHODS: Using a standardized script, patients scheduled for arthroscopic shoulder surgery were informed of the risks of ISB by an anesthesiologist in the preoperative assessment clinic. Immediately thereafter, consenting participants were asked to identify the risks of ISB from a printed list of nine true risks (four major and five minor) and nine 'distractor' items, which were unrelated adverse events and not disclosed. The primary outcome was the proportion of participants who remembered all four true major risks including long-term nerve damage, seizure, life-threatening event, and damage to the covering of the lung. RESULTS: Among 125 participants, only 26 (21%) remembered all four major risks of ISB. The mean number of major risks remembered was 2±1 out of 4. Fifteen (12%) participants remembered all nine true risks. The mean number of true risks remembered was 6±2 out of 9. Multivariable analysis revealed that participants' self-rated assessment of their memory was not associated with actual recall. CONCLUSION: Patients have poor immediate memory of the major risks related to ISB disclosed during the informed consent discussion. Under the present study conditions, the validity of the informed consent process for patients undergoing ISB may be undermined.

Fluid resuscitation in sepsis: reexamining the paradigm.

Sepsis results in widespread inflammatory responses altering homeostasis. Associated circulatory abnormalities (peripheral vasodilation, intravascular volume depletion, increased cellular metabolism, and myocardial depression) lead to an imbalance between oxygen delivery and demand, triggering end organ injury and failure. Fluid resuscitation is a key part of treatment, but there is little agreement on choice, amount, and end points for fluid resuscitation. Over the past few years, the safety of some fluid preparations has been questioned. Our paper highlights current concerns, reviews the science behind current practices, and aims to clarify some of the controversies surrounding fluid resuscitation in sepsis.