Predictors of a difficult intubation in the bariatric patient: does preoperative body mass index matter?

Preoperative Assessment of a Patient Undergoing Bariatric Surgery

Over the past few decades, obesity rates in the United States have risen drastically, and with this, there has been a rising demand for bariatric surgery. As such, anesthesiologists need to be familiar with the challenges presented by patients seeking bariatric surgery. Obesity causes pathophysiologic changes which may affect decision-making during the management of these patients. Patients seeking bariatric surgery also have a long, prescribed preoperative course that offers anesthesiologists the opportunity to be involved earlier during the pre-surgical evaluation and optimization process.

2022 American Society of Anesthesiologists Practice Guidelines for Management of the Difficult Airway

The American Society of Anesthesiologists; All India Difficult Airway Association; European Airway Management Society; European Society of Anaesthesiology and Intensive Care; Italian Society of Anesthesiology, Analgesia, Resuscitation and Intensive Care; Learning, Teaching and Investigation Difficult Airway Group; Society for Airway Management; Society for Ambulatory Anesthesia; Society for Head and Neck Anesthesia; Society for Pediatric Anesthesia; Society of Critical Care Anesthesiologists; and the Trauma Anesthesiology Society present an updated report of the Practice Guidelines for Management of the Difficult Airway.

Canadian Airway Focus Group updated consensus-based recommendations for management of the difficult airway: part 2. Planning and implementing safe management of the patient with an anticipated difficult airway

PURPOSE

Since the last Canadian Airway Focus Group (CAFG) guidelines were published in 2013, the published airway management literature has expanded substantially. The CAFG therefore re-convened to examine this literature and update practice recommendations. This second of two articles addresses airway evaluation, decision-making, and safe implementation of an airway management strategy when difficulty is anticipated.

SOURCE

Canadian Airway Focus Group members, including anesthesia, emergency medicine, and critical care physicians were assigned topics to search. Searches were run in the Medline, EMBASE, Cochrane Central Register of Controlled Trials, and CINAHL databases. Results were presented to the group and discussed during video conferences every two weeks from April 2018 to July 2020. These CAFG recommendations are based on the best available published evidence. Where high-quality evidence is lacking, statements are based on group consensus.

FINDINGS AND KEY RECOMMENDATIONS

Prior to airway management, a documented strategy should be formulated for every patient, based on airway evaluation. Bedside examination should seek predictors of difficulty with face-mask ventilation (FMV), tracheal intubation using video- or direct laryngoscopy (VL or DL), supraglottic airway use, as well as emergency front of neck airway access. Patient physiology and contextual issues should also be assessed. Predicted difficulty should prompt careful decision-making on how most safely to proceed with airway management. Awake tracheal intubation may provide an extra margin of safety when impossible VL or DL is predicted, when difficulty is predicted with more than one mode of airway management (e.g., tracheal intubation and FMV), or when predicted difficulty coincides with significant physiologic or contextual issues. If managing the patient after the induction of general anesthesia despite predicted difficulty, team briefing should include triggers for moving from one technique to the next, expert assistance should be sourced, and required equipment should be present. Unanticipated difficulty with airway management can always occur, so the airway manager should have a strategy for difficulty occurring in every patient, and the institution must make difficult airway equipment readily available. Tracheal extubation of the at-risk patient must also be carefully planned, including assessment of the patient's tolerance for withdrawal of airway support and whether re-intubation might be difficult.

Perioperative care of the obese patient

Background

Obesity has become an increasing problem worldwide during the past few decades. Hence, surgeons and anaesthetists will care for an increasing number of obese patients in the foreseeable future, and should be prepared to provide optimal management for these individuals. This review provides an update of recent evidence regarding perioperative strategies for obese patients.

Methods

A search for papers on the perioperative care of obese patients (English language only) was performed in July 2019 using the PubMed, Scopus, Web of Science and Cochrane Library electronic databases. The review focused on the results of RCTs, although observational studies, meta-analyses, reviews, guidelines and other reports discussing the perioperative care of obese patients were also considered. When data from obese patients were not available, relevant data from non-obese populations were used.

Results and conclusion

Obese patients require comprehensive preoperative evaluation. Experienced medical teams, appropriate equipment and monitoring, careful anaesthetic management, and an adequate perioperative ventilation strategy may improve postoperative outcomes. Additional perioperative precautions are necessary in patients with severe morbid obesity, metabolic syndrome, untreated or severe obstructive sleep apnoea syndrome, or obesity hypoventilation syndrome; patients receiving home ventilatory support or postoperative opioid therapy; and obese patients undergoing open operations, long procedures or revisional surgery.

Retrospective Evaluation of Patients who Underwent Laparoscopic Bariatric Surgery

OBJECTIVE

In the present study, we aimed to retrospectively evaluate the preoperative characteristics, intraoperative and postoperative results of patients who underwent laparoscopic obesity surgeries.

METHODS

After obtaining the approval of the Ethics Committee, records of patients who underwent laparoscopic obesity surgery from January 2013 to December 2016 were reviewed. Demographic characteristics, medications used in anaesthesia and analgesia, the duration of recovery unit/hospital stay, intensive care unit/mechanical ventilation requirements and complications were recorded.

RESULTS

A total of 329 ASA II-III patients over a 3-year period were operated. Thiopental and propofol were administered at induction, sevoflurane, isoflurane and desflurane were administered for the maintenance, and vecuronium and rocuronium were administered to aid in neuromuscular blockage. The mean durations of recovery unit and hospital stays were 30.80±6.01 minutes and 4.27±1.68 days, respectively. The hypnotic agent, muscle relaxant or inhalation anaesthetics used did not have a significant effect on the duration of recovery unit and hospital stay. Mask ventilation and intubation were noted to be difficult in 5.5% and 8.5% of the cases, respectively. The presence of obstructive sleep apnoea syndrome and high body mass index and Mallampati scores significantly increased difficult mask ventilation and difficult intubation rates. Four patients were transferred to intensive care unit for close monitoring. Two patients were re-operated on, two patients had rhabdomyolysis, one patient had Wernicke's encephalopathy and two patients had peripheral neuropathy. Perioperative mortality did not occur in any patient.

CONCLUSION

We believe that appropriate patient selection, the use of well-designed anaesthesia and surgical protocols play important roles in increasing the success rate of patient outcomes and early and late complications in laparoscopic obesity surgery.

Pre-selection of primary intubation technique is associated with a low incidence of difficult intubation in patients with a BMI of 35 kg/m2 or higher

Background

The incidence of difficult intubation (DI) in obese patients may reach a two-digit figure. No studies have assessed the effect of primary use of special intubation devices on lowering the incidence of DI. We assessed the effect of primary selection of special intubation techniques on the incidence of DI in patients with a BMI of 35 kg/m² or higher.

Patients and methods

Data from 546 patients with a BMI of 35 kg/m² or higher who underwent bariatric surgery at Wolfson Medical Center from 2010 through 2014 was retrospectively extracted and analyzed for demographics, predictors of DI and intubation techniques employed. Difficult intubation was defined as the presence of at least one of the followings: laryngoscopy grade 3 or 4, need for >1 laryngoscopy or intubation attempt, need for changing the blade size, failed direct laryngoscopy (DL), difficult or failed videolaryngoscopy (VL-Glidescope), difficult or failed awake fiberoptic intubation (AFOI) and using VL or awake AFOI as rescue airway techniques. Primary intubation techniques were direct DL, VL and AFOI. We correlated the predictors of DI with the actual incidence of DI and with the choice of intubation technique employed.

Results

The overall incidence of DI was 1.6% (1.5% with DL vs. 2.2 with VL + AFOI, p = 0.61). With logistic regression analysis, age was the only significant predictor of DI. Predictors of DI that affected the selection of VL or AFOI as primary intubation tools were Mallampati class 3 or 4, limited neck movement, age, male gender, body mass index and obstructive sleep apnea syndrome.

Conclusion

The lower incidence of DI in our study group may stem from the primary use of special intubation devices, based on the presence of predictors of DI.

Management of the Difficult Airway in the Pediatric Patient

Loss of airway control in children, if not resolved quickly, will lead to devastating consequences. Successful management of the pediatric difficult airway, both anticipated and unanticipated, is facilitated by preprocedure assessment and preparation. Accessibility of and continued hands-on training with modern airway instruments, familiarization with difficult airway guidelines, and collaboration with multidisciplinary airway teams can aid in the management of the difficult pediatric airway. This review outlines the importance of airway assessment and advanced airway equipment for children. It also discusses difficult airway management techniques and algorithms for the management and rescue of the pediatric difficult airway.

Does Body Mass Index Reduction by Bariatric Surgery Affect Laryngoscopy Difficulty During Subsequent Anesthesia?

BACKGROUND

The effect of body mass index (BMI) reduction following bariatric surgery on subsequent airway management has not been investigated. This study aimed to investigate the association between BMI reduction and airway assessment and management measured by Mallampati class (MC) and laryngoscopy grade (LG).

METHODS

We conducted a retrospective study over 6 years to compare the BMI changes, MC and LG in patients having weight reduction bariatric surgery followed by subsequent surgery. Data was extracted from the anesthesia records of patients undergoing laparoscopic band insertion (LBI) and laparoscopic sleeve gastrectomy (LSG). Difficult airway was defined as Malampati class 3 and 4 on a 1-4 difficulty scale or laryngoscopy grade >2 on a 1-4 difficulty scale and need for unplanned fiberoptic intubation. Changes in these variables were correlated with weight reduction. Statistical analysis included t test, univariante, and multivariant logistic regression.

RESULTS

Five hundred forty-six patients underwent LSG and 83 patients had LBI during the study period. Of those patients, 65 patients had subsequent surgical procedures after the bariatric procedure. Of the 65 patients identified, 62 were eligible. BMI decreased by approximately13 kg/m² (p = 0.000) which roughly represents a 30 % reduction between the two surgical procedures. Mallampati class decreased significantly (p = 0.000) while laryngoscopy grade did not (p = 0.419).

CONCLUSION

Our study revealed that a significant reduction in BMI was associated with a significant decrease in Mallampati class. There was no significant decrease in laryngoscopy grade, and there was no case of unplanned fiberoptic intubation.

Validation of modified Mallampati test with addition of thyromental distance and sternomental distance to predict difficult endotracheal intubation in adults

Background and Aims:

Intubation is often a challenge for anaesthesiologists. Many parameters assist to predict difficult intubation. The present study was undertaken to assess the validity of different parameters in predicting difficult intubation for general anaesthesia (GA) in adults and effect of combining the parameters on the validity.

Methods:

The anaesthesiologist assessed oropharynx of 135 adult patients. Modified Mallampati test (MMT) was used and the thyromental distance (TMD) and sternomental distances (SMD) for each of the patients were also measured. The Cormack and Lehane laryngoscopic grading was assessed following laryngoscopy. The validity parameters such as sensitivity, specificity, false positive and negatives values, positive and negative predictive values were calculated. The effect of combining different measurements on the validity was also studied. Univariate analysis was performed using the parametric method.

Results:

The study group comprised of 135 patients. The sensitivity and specificity of MMT were 28.6% and 93%, respectively. The TMD (<6.5 CM) had sensitivity and specificity of 100% and 75.8%, respectively. The SMD (<12.5 CM) had sensitivity and specificity of 91% and 92.7%, respectively. Combination of MMT grading and TMD and SMD measurements increased the validity (sensitivity of 100% and specificity of 92.7%).

Conclusion:

MMT had high specificity. The validity of combination of MMT, SMD and TMD as compared to MMT alone was very high in predicting difficult intubation in adult patients. All parameters should be used in assessing an adult patient for surgery under GA.

Anesthesia for bariatric surgery: 8-year retrospective study: are our patients now easier to manage?

OBJECTIVES

To review the perioperative management of patients who had undergone bariatric surgery in our institution during an 8-year period, with the aim of identifying variables that correlated with improved clinical outcomes and changes in perioperative practice.

METHODS

This was a retrospective observational study of 437 patients who had undergone bariatric surgery from January 2005 to June 2013. Of these patients, 163 had undergone open or laparoscopic biliopancreatic diversion (Group 1), and 274 had been managed according to a Tailored Laparoscopic Approach Program (TLAP) (Group 2). We analyzed major cardiocirculatory, pulmonary, and surgery-related complications, mortality rate, intensive care unit (ICU) admissions, post-anesthetic care unit (PACU) length of stay, and perioperative management standards, throughout the study period.

RESULTS

Changes were observed in anesthetic patterns and perioperative care standards during the study period: 25% of patients had combined epidural anesthesia in 2005, compared with none at present; ICU admissions decreased from 28.6% in 2005 to 3.1% at present; and time in PACU declined from a median of 23 h in 2005 to 5.12h at present. Duration of postoperative opioid therapy was also significantly reduced (from 48 h to 6h). Group 2 had a significantly lower mortality rate than Group 1 (0.37% versus 4.3%, respectively, P=0.004).

CONCLUSIONS

In our institution, adoption of a TLAP for bariatric surgery has led to changes in perioperative care standards that have been followed by clear improvements according to morbidity, mortality and management indicators.