Effects of A-Line Autoregression Index (AAI) Monitoring on Recovery After Sevoflurane Anesthesia for Bariatric Surgery

Obstructive Sleep Apnea and Risk of Postoperative Complications after Non-Cardiac Surgery

Obstructive sleep apnea (OSA), a common sleep disorder, poses significant challenges in perioperative management due to its complexity and multifactorial nature. With a global prevalence of approximately 22.6%, OSA often remains undiagnosed, and increases the risk of cardiac and respiratory postoperative complications. Preoperative screening has become essential in many institutions to identify patients at increased risk, and experts recommend proceeding with surgery in the absence of severe symptoms, albeit with heightened postoperative monitoring. Anesthetic and sedative agents exacerbate upper airway collapsibility and depress central respiratory activity, complicating intraoperative management, especially with neuromuscular blockade use. Additionally, OSA patients are particularly prone to opioid-induced respiratory depression, given their increased sensitivity to opioids and heightened pain perception. Thus, regional anesthesia and multimodal analgesia are strongly advocated to reduce perioperative complication risks. Postoperative care for OSA patients necessitates vigilant monitoring and tailored management strategies, such as supplemental oxygen and Positive Airway Pressure therapy, to minimize cardiorespiratory complications. Health care institutions are increasingly focusing on enhanced monitoring and resource allocation for patient safety. However, the rising prevalence of OSA, heterogeneity in disease severity, and lack of evidence for the efficacy of costly perioperative measures pose challenges. The development of effective screening and monitoring algorithms, alongside reliable risk predictors, is crucial for identifying OSA patients needing extended postoperative care. This review emphasizes a multidimensional approach in managing OSA patients throughout the perioperative period, aiming to optimize patient outcomes and minimize adverse outcomes.

Intraoperative Monitoring of the Obese Patient Undergoing Surgery: A Narrative Review

With the increasing prevalence of obesity in the population, anaesthetists must confidently manage both the pathophysiological and technical challenges presented in bariatric and non-bariatric surgery. The intraoperative period represents an important opportunity to optimise and mitigate risk. However, there is little formal guidance on what intraoperative monitoring techniques should be used in this population. This narrative review collates the existing evidence for intraoperative monitoring devices in the obese patients. Although a number of non-invasive blood pressure monitors have been tested, an invasive arterial line remains the most reliable monitor if accurate, continuous monitoring is required. Goal-directed fluid therapy is recommended by clinical practice guidelines, but the methods tested to assess this had guarded applicability to the obese population. Transcutaneous carbon dioxide (CO₂) monitoring may offer additional benefit to standard capnography in this population. Individually titrated positive end expiratory pressure (PEEP) and recruitment manoeuvres improved intraoperative mechanics but yielded no benefit in the immediate postoperative period. Depth of anaesthesia monitoring appears to be beneficial in the perioperative period regarding recovery times and complications. Objective confirmation of reversal of neuromuscular blockade continues to be a central tenet of anaesthesia practice, particularly relevant to this group who have been characterised as an "at risk" extubation group. Where deep neuromuscular blockade is used, continuous neuromuscular blockade is suggested. Both obesity and the intraoperative context represent somewhat unstable search terms, as the clinical implications of the obesity phenotype are not uniform, and the type and urgency of surgery have significant impact on the intraoperative setting. This renders the generation of summary conclusions around what intraoperative monitoring techniques are suitable in this population highly challenging.

Perioperative Management of the Patient With Obstructive Sleep Apnea: A Narrative Review

The prevalence of obstructive sleep apnea (OSA) has reached 1 billion people worldwide, implying significant risk for the perioperative setting as patients are vulnerable to cardiopulmonary complications, critical care requirement, and unexpected death. This review summarizes main aspects and considerations for the perioperative management of OSA, a condition of public health concern. Critical determinants of perioperative risk include OSA-related changes in upper airway anatomy with augmented collapsibility, diminished capability of upper airway dilator muscles to respond to airway obstruction, disparities in hypoxemia and hypercarbia arousal thresholds, and instability of ventilatory control. Preoperative OSA screening to identify patients at increased risk has therefore been implemented in many institutions. Experts recommend that in the absence of severe symptoms or additional compounding health risks, patients may nevertheless proceed to surgery, while heightened awareness and the adjustment of postoperative care is required. Perioperative caregivers should anticipate difficult airway management in OSA and be prepared for airway complications. Anesthetic and sedative drug agents worsen upper airway collapsibility and depress central respiratory activity, while the risk for postoperative respiratory compromise is further increased with the utilization of neuromuscular blockade. Consistently, opioid analgesia has proven to be complex in OSA, as patients are particularly prone to opioid-induced respiratory depression. Moreover, basic features of OSA, including intermittent hypoxemia and repetitive sleep fragmentation, gradually precipitate a higher sensitivity to opioid analgesic potency along with an increased perception of pain. Hence, regional anesthesia by blockade of neural pathways directly at the site of surgical trauma as well as multimodal analgesia by facilitating additive and synergistic analgesic effects are both strongly supported in the literature as interventions that may reduce perioperative complication risk. Health care institutions are increasingly allocating resources, including those of postoperative enhanced monitoring, in an effort to increase patient safety. The implementation of evidence-based perioperative management strategies is however burdened by the rising prevalence of OSA, the large heterogeneity in disease severity, and the lack of evidence on the efficacy of costly perioperative measures. Screening and monitoring algorithms, as well as reliable risk predictors, are urgently needed to identify OSA patients that are truly in need of extended postoperative surveillance and care. The perioperative community is therefore challenged to develop feasible pathways and measures that can confer increased patient safety and prevent complications in patients with OSA.

Analgesic and Antidepressant Effects of the Clinical Glutamate Modulators Acetyl-L-Carnitine and Ketamine

Pain and depression are leading causes of disability and of profound social and economic burden. Their impact is aggravated by their chronicity and comorbidity and the insufficient efficacy of current treatments. Morphological and functional metabolism studies link chronic pain and depressive disorders to dysfunctional neuroplastic changes in fronto-limbic brain regions that control emotional responses to painful injuries and stressful events. Glutamate modulators are emerging new therapies targeting dysfunctional brain areas implicated in the generation and maintenance of chronic pain and depression. Here, we report the effects of two clinically approved glutamate modulators: acetyl-L-carnitine (ALCAR) and S, R(±)ketamine (KET). ALCAR is a natural neurotrophic compound currently marketed for the treatment of neuropathies. KET is the prototypical non-competitive antagonist at N-methyl-D-aspartate glutamate receptors and a clinically approved anesthetic. Although they differ in pharmacological profiles, ALCAR and KET both modulate aminergic and glutamatergic neurotransmissions and pain and mood. We assessed in rats the effects of ALCAR and KET on cerebral metabolic rates for glucose (rCMRglc) and assessed clinically the effects of ALCAR in chronic pain and of KET in post-operative pain. ALCAR and KET increased rCMRglc at similar degrees in prefrontal, somatosensory, and cingulate cortices, and KET increased rCMRglc at a different, much larger, degree in limbic and dopaminergic areas. While rCMRglc increases in prefrontal cortical areas have been associated with analgesic and antidepressant effects of ALCAR and KET, the marked metabolic increases KET induces in limbic and dopaminergic areas have been related to its psychotomimetic and abuse properties. In patients with chronic neuropathic pain, ALCAR (1,000 mg/day) yielded to a fast (2 weeks) improvement of mood and then of pain and quality of life. In day-surgery patients, KET improved dischargeability and satisfaction. In obese patients undergoing bariatric surgery, a single, low dose of KET (0.5 mg/kg) at induction of anesthesia determined a very fast (hours) amelioration of post-operative depression and pain and an opioid-sparing effect. These findings indicate that ALCAR and KET, two non-selective glutamate modulators, still offer viable therapeutic options in comorbid pain and depression.

Effect of Patient State Index Monitoring on the Recovery Characteristics in Morbidly Obese Patients: Comparison of Inhalation Anesthesia and Total Intravenous Anesthesia

PURPOSE

Obese patients have a significantly higher risk of adverse effects associated with general anesthesia. The purpose of this study was to evaluate the effects of Patient State Index (PSI) monitoring on recovery from anesthesia and the incidence of any postoperative complications among patients undergoing bariatric surgery with total intravenous anesthesia (TIVA) and inhalational anesthesia.

DESIGN

This prospective, double-blind, and randomized controlled trial was conducted between February 2017 and August 2017 and included 120 morbidly obese patients (body mass index >40 kg/m²).

METHODS

Patients were randomly divided into four groups; group P-PSI (n = 30): TIVA with PSI monitoring; group P (n = 30): TIVA without PSI monitoring; group D-PSI (n = 30): desflurane with PSI monitoring; and group D (n = 30): desflurane without PSI monitoring. The discharge time from the postanesthesia care unit (PACU), postoperative complications, and hemodynamic parameters were recorded and evaluated.

FINDINGS

No significant differences were found in demographic data, duration of anesthesia, admittance to PACU, discharge from PACU, modified Aldrete scores, and perioperative mean blood pressure and heart rate. Nausea and vomiting scores were significantly lower in group P-PSI, group P, and group D-PSI compared with group D.

CONCLUSIONS

Although TIVA and inhalational anesthesia can be safely used for obese patients, intraoperative PSI monitoring may decrease the discharge time from PACU and reduces incidence of postoperative nausea and vomiting caused by inhalation anesthetics.

Society of Anesthesia and Sleep Medicine Guideline on Intraoperative Management of Adult Patients With Obstructive Sleep Apnea

The purpose of the Society of Anesthesia and Sleep Medicine Guideline on Intraoperative Management of Adult Patients With Obstructive Sleep Apnea (OSA) is to present recommendations based on current scientific evidence. This guideline seeks to address questions regarding the intraoperative care of patients with OSA, including airway management, anesthetic drug and agent effects, and choice of anesthesia type. Given the paucity of high-quality studies with regard to study design and execution in this perioperative field, recommendations were to a large part developed by subject-matter experts through consensus processes, taking into account the current scientific knowledge base and quality of evidence. This guideline may not be suitable for all clinical settings and patients and is not intended to define standards of care or absolute requirements for patient care; thus, assessment of appropriateness should be made on an individualized basis. Adherence to this guideline cannot guarantee successful outcomes, but recommendations should rather aid health care professionals and institutions to formulate plans and develop protocols for the improvement of the perioperative care of patients with OSA, considering patient-related factors, interventions, and resource availability. Given the groundwork of a comprehensive systematic literature review, these recommendations reflect the current state of knowledge and its interpretation by a group of experts at the time of publication. While periodic reevaluations of literature are needed, novel scientific evidence between updates should be taken into account. Deviations in practice from the guideline may be justifiable and should not be interpreted as a basis for claims of negligence.

Non-instrumental clinical monitoring does not guarantee an adequate course of general anesthesia. A prospective clinical study

BACKGROUND

Clinical monitoring is the most common method of adjusting the appropriate level of general anesthesia. However, episodes of intraoperative awareness (AWR) are still reported, suggesting that clinical observations may not be sufficient in some cases. The objective of this study was to compare the efficacy of clinical and instrumental neuromonitoring with auditory evoked potentials (AEP) in an intraoperative analysis of the proper level of general anesthesia.

METHODS

Patients scheduled for elective surgery were randomly divided into two groups. Subjects in the first group underwent intravenous, in the second group volatile anesthesia. The adequacy of anesthesia was analyzed using clinical parameters. All the participants were instrumentally monitored with the autoregressive AEP index (AAI). After the anesthesia, patients filled out a questionnaire on possible AWR.

RESULTS

Data of 208 patients (87 in the first, and 121 in the second group) were analyzed. Before surgery there were no changes in AAI values between groups (80 vs. 78, P=0.5192). The mean values of clinical parameters changed, but five minutes after the nociceptive stimuli. The mean values of AAI at analyzed time points were specific for general anesthesia. In patients under intravenous anesthesia, we found more episodes of too low (46/608 vs.15/847, P<0.000) anesthesia. One case of AWR was found in the TIVA group.

CONCLUSIONS

AAI index is good indicator of patients' level of consciousness during general anesthesia. Standard clinical monitoring provides appropriate level of the procedure. However, it is insufficient during TIVA and does not prevent episodes of AWR.