What's new in anesthesiology

The following represent additions to UpToDate from the past six months that were considered by the editors and authors to be of particular interest. The most recent What's New entries are at the top of each subsection.

AIRWAY MANAGEMENT

Obesity and increased risk of perioperative cardiac arrest (March 2024)

Obesity is a risk factor for difficulty with airway management and for rapid apneic oxygen desaturation during airway management. Both can result in hypoxic brain damage or death. In an analysis of causes of perioperative cardiac arrest reported to the Seventh National Audit Project (NAP7) in the United Kingdom, 35 percent of airway- and respiratory-related cardiac arrests occurred in patients with body mass index 35 to 50 kg/m², while this cohort comprised only 12 percent of the survey population [1]. These findings reinforce the need to consider obesity when choosing general versus regional anesthesia and planning the airway management strategy. (See "Airway management for induction of general anesthesia", section on 'Obesity as a risk factor'.)

CARDIOVASCULAR AND THORACIC ANESTHESIA

Moderate hypothermia during aortic arch surgery with antegrade cerebral perfusion (March 2024)

Observational data have supported a shift from deep to moderate hypothermia during circulatory arrest for aortic arch surgery, particularly with adjunctive antegrade cerebral perfusion (ACP). A recent trial has now compared outcomes for 251 patients undergoing aortic arch surgery with ACP and randomly assigned to deep (≤20.0°C), low-moderate (20.1 to 24.0°C), or high-moderate (24.1 to 28.0°C) circulatory arrest temperature [2]. At one-month follow-up, the three groups had similar neurocognitive and neuroimaging outcomes and similar mortality, major morbidity, and quality of life. The volume of transfused blood products was higher in the deep group, but transfusion-related complications were not different. Based on this trial, moderate (20.1 to 28.0°C) rather than deep hypothermia is reasonable during aortic arch surgery when ACP is also used. Whether a low-moderate or high-moderate temperature is selected depends on the complexity of the arch intervention and the anticipated duration of hypothermia. (See "Overview of open surgical repair of the thoracic aorta", section on 'Hypothermic circulatory arrest'.)

OBSTETRIC ANESTHESIA

Labor epidural analgesia and risk of emergency delivery (December 2023)

It is well established that contemporary neuraxial labor analgesia does not increase the overall risk of cesarean or instrument-assisted vaginal delivery. However, a new retrospective database study of over 600,000 deliveries in the Netherlands reported that epidural labor analgesia was associated with an increased risk of emergency delivery (cesarean or instrument-assisted vaginal) compared with alternative analgesia (13 versus 7 percent) [3]. Because of potential confounders and lack of detail on epidural and obstetric management, we consider these data insufficient to avoid neuraxial analgesia or change the practice of early labor epidural placement to reduce the potential need for general anesthesia in patients at high risk for cesarean delivery. (See "Adverse effects of neuraxial analgesia and anesthesia for obstetrics", section on 'Effects on the progress and outcome of labor'.)

PATIENT SAFETY

Use of a formal handoff tool during intraoperative transfer of anesthetic care (March 2024)

Intraoperative handoffs of care from one anesthesia provider to another have been associated with adverse outcomes, possibly due to inadequate communication of clinical information. A retrospective study noted that an intraoperative handoff (defined as transfer of care lasting more than 35 minutes) occurred in 40 percent of approximately 120,000 noncardiac surgical cases performed from 2016 to 2021 [4]. Adverse outcomes (defined as a composite of postoperative mortality or major morbidity) occurred more often when a handoff occurred (7.2 versus 6.2 percent with no handoff). After implementation of a structured electronic handoff tool in 2019, a correlation over time was noted between increased handoff tool usage and decreased likelihood of the composite adverse outcome. We use a formal handoff protocol during all phases of perioperative care. (See "Handoffs of surgical patients", section on 'Use of a formal handoff procedure'.)

PEDIATRIC ANESTHESIA

New guidelines for airway management in infants (January 2024)

Very young children are at higher risk of complications of airway management than children in older age groups; however, guidelines for infants have been lacking. In 2024, the European Society of Anesthesiology and Intensive Care and the British Journal of Anesthesia published joint guidelines for airway management in neonates and infants [5]. A summary of their recommendations appears in the following table (table 1). (See "Airway management for pediatric anesthesia", section on 'Pediatric airway management guidelines'.)

Videolaryngoscopy for endotracheal intubation in critically ill children (January 2024)

Use of videolaryngoscopy (VL) in children provides a shared view during emergency endotracheal intubation (ETI) that permits an experienced physician observer to give assistance to the proceduralist. In a multicenter quality study of VL during ETI in pediatric intensive care units with standardized coaching by an attending, over 3500 ETIs were performed with VL, and use of VL increased from 30 percent to 89 percent of ETIs over four years [6]. Compared with direct laryngoscopy, VL was associated with lower adverse events (9 versus 15 percent). The majority of proceduralists were residents or fellows. These findings and prior studies confirm the safety of VL during emergency ETI in children and demonstrate the value of standardized coaching during the procedure for less experienced clinicians. (See "Technique of emergency endotracheal intubation in children", section on 'Video versus direct laryngoscopy'.)

PREOPERATIVE AND POSTOPERATIVE MANAGEMENT

Association of preoperative anemia with adverse outcomes after cardiac surgery (March 2024)

Studies continue to show a high rate of preoperative anemia in patients undergoing cardiac surgery and an association with adverse surgical outcomes. In a retrospective study of >4000 patients undergoing coronary artery bypass grafting surgery, 30 percent had preoperative anemia, which was associated with dose-dependent increases in postoperative acute kidney injury (AKI) and longer hospital stay [7]. In a 2024 meta-analysis with nearly 160,000 patients who underwent cardiac surgery, 28 percent had preoperative anemia, which was associated with increased mortality, AKI, other morbidities, and longer hospital stay [8]. When feasible, we postpone major surgery in patients with anemia to diagnose the cause and provide treatment. (See "Perioperative blood management: Strategies to minimize transfusions", section on 'Treatment of anemia'.)

Postoperative noninvasive ventilation or high-flow nasal oxygen for patients with obesity (November 2023)

The optimal postoperative ventilatory strategy for patients with severe obesity has been unclear. In a 2023 network meta-analysis of randomized trials that compared various postoperative noninvasive ventilatory strategies in these patients, high-flow nasal oxygen (HFNO) or bilevel positive airway pressure (BiPAP) reduced atelectasis; HFNO, BiPAP, or continuous positive airway pressure (CPAP) reduced postoperative pneumonia; and HFNO reduced length of stay compared with conventional oxygen therapy [9]. For patients with obesity who are hypoxic in the post-anesthesia care unit despite oxygen supplementation and incentive spirometry, we suggest a trial of HFNO, BiPAP, or CPAP prior to considering intubation. (See "Anesthesia for the patient with obesity", section on 'Post-anesthesia care unit management'.)

REGIONAL ANESTHESIA

Anti-factor Xa levels 24 hours after the last therapeutic enoxaparin dose (April 2024)

Guidelines recommend waiting 24 hours after a therapeutic dose of low molecular weight heparin (LMWH) before performing neuraxial anesthesia, to minimize the risk of spinal epidural hematoma (SEH). However, anti-factor Xa levels (which test LMWH activity) may still be elevated 24 hours after the last dose. In a study of 103 patients taking therapeutic dose enoxaparin, 23 percent had an anti-factor Xa level ≥0.2 international units/mL at ≥24 hours after the last dose [10]. The implications of these findings are unclear, as a safe anti-factor Xa level for performing neuraxial procedures has not been determined and there has not been a noticeable increase in SEH in patients who have withheld LMWH according to current guidelines. (See "Neuraxial anesthesia/analgesia techniques in the patient receiving anticoagulant or antiplatelet medication", section on 'Therapeutic LMWH'.)

OTHER ANESTHESIA

Updated guideline on postoperative delirium in adults (February 2024)

The European Society of Anaesthesiology and Intensive Care Medicine has published an updated guideline on postoperative delirium (POD) [11]. Recommendations include preoperatively screening older adults for risk factors for POD and multicomponent nonpharmacological interventions for all patients with risk factors. In addition, review of recent evidence showed that perioperative use of dexmedetomidine was associated with a lower incidence of POD, particularly when administered postoperatively in the intensive care unit. We agree with the recommendations and often use dexmedetomidine in the perioperative period to reduce the incidence of POD in high-risk patients. (See "Perioperative neurocognitive disorders in adults: Risk factors and mitigation strategies", section on 'Intravenous agents associated with lower risk'.)

Supplemental neuraxial or regional analgesia and postoperative neurocognitive disorders (January 2024)

Supplementing general anesthesia with neuraxial or regional analgesic techniques reduced postoperative neurocognitive disorders (PND) and/or delirium in some studies, but results have been inconsistent. Differences in techniques and timing of analgesic administration, and confounding patient variables may explain the inconsistencies. In a meta-analysis of randomized trials of patients undergoing major noncardiac surgery under general or neuraxial anesthesia, supplemental postoperative neuraxial or regional analgesia (eg, epidural or peripheral or fascial plane block) reduced PND (both delirium and delayed neurocognitive recovery) in the first postoperative month compared with no supplemental analgesia [12]. Although supplemental analgesia may reduce PND, selection of anesthetic techniques is based primarily on other considerations. (See "Perioperative neurocognitive disorders in adults: Risk factors and mitigation strategies", section on 'Choice of anesthetic technique'.)

Thyroid hormone administration in deceased organ donors (December 2023)

Thyroid hormone administration has been a longstanding component of some organ procurement protocols due to concern that acute hypothyroidism might contribute to hemodynamic instability and left ventricular dysfunction, reducing heart and other organ procurement; however, evidence for the practice has been inconsistent. In a recent trial of 838 hemodynamically unstable, brain-dead donors assigned to receive a levothyroxine infusion or saline placebo, there was little to no difference in number of hearts transplanted or 30-day cardiac graft survival [13]. Recovery of other organs was similarly unaffected. More cases of severe hypertension or tachycardia occurred in the levothyroxine group than in the saline group. Based on these data, we suggest avoiding thyroid hormone administration in deceased organ donors. (See "Management of the deceased organ donor", section on 'Thyroid hormone'.)