ProSeal™ LMA increases safe apnea period in morbidly obese patients undergoing surgery under general anesthesia

Enhanced recovery after bariatric surgery: an Italian consensus statement

Background

Enhanced recovery after bariatric surgery (ERABS) is an approach developed to improve outcomes in obese surgical patients. Unfortunately, it is not evenly implemented in Italy. The Italian Society for the Surgery of Obesity and Metabolic Diseases and the Italian Society of Anesthesia, Analgesia, Resuscitation and Intensive Care joined in drafting an official statement on ERABS.

Methods

To assess the effectiveness and safety of ERABS and to develop evidence-based recommendations with regard to pre-, intra-, and post-operative care for obese patients undergoing ERABS, a 13-member expert task force of surgeons and anesthesiologists from Italian certified IFSO center of excellence in bariatric surgery was established and a review of English-language papers conducted. Oxford 2011 Levels of Evidence and U.S. Preventive Services Task Force Grade Definitions were used to grade the level of evidence and the strength of recommendations, respectively. The supporting evidence and recommendations were reviewed and discussed by the entire group at meetings to achieve a final consensus.

Results

Compared to the conventional approach, ERABS reduces the length of hospital stay and does not heighten the risk of major post-operative complications, re-operations, and hospital re-admissions, nor does it increase the overall surgical costs. A total of 25 recommendations were proposed, covering pre-operative evaluation and care (7 items), intra-operative management (1 item, 11 sub-items), and post-operative care and discharge (6 items).

Conclusions

ERABS is an effective and safe approach. The recommendations allow the proper management of obese patients undergoing ERABS for a better outcome.

Predictors of difficult airway in the obese are closely related to safe apnea time!

Background and Aims:

We aimed to redefine the preoperative factors that may challenge the airway and safe apnea time (SAT) in the obese.

Material and Methods:

We analyzed 834 patients with body mass index (BMI) >35 kg/m² for their difficult airway score (DASc). DASc is a consolidation of measures of difficult airway like mask ventilation, difficult intubation, change of device, and number of personnel required. DASc varied from “0” no difficulty to “12” serious difficulty and DASc ≥6 was considered difficult. Preoperative parameters – neck circumference (NC), BMI, STOPBANG score, Mallampati score, obstructive sleep apnea grade, and waist circumference– were assessed.

Results:

Receiver operating characteristic curve was used to identify risk factors for obese patients at DASc ≥6. The Youden index (for the best threshold, with highest sensitivity and specificity) was BMI 45 kg/m² and NC 44.5 cm. Their absence had an 81% negative predictive value to include a difficult airway, while their presence had a positive predictive value of 55%. This further has sensitivity of 66% and specificity of 73%. The mean SAT (256 ± 6 s) was inversely related to DASc (P < 0.001).

Conclusion:

This study demonstrates that BMI and NC have a strong association with difficult airway in obese patients and are inversely related to SAT. Amongst these NC is the single most important predictor of difficult airway in obese and should be used as a screening tool.

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.

Dexmedetomidine reduces sevoflurane EC50 for supraglottic airway device insertion in spontaneously breathing morbidly obese patients

Purpose: This study aimed to assess the effect of intravenous dexmedetomidine (DEX) on sevoflurane EC₅₀ for supraglottic airway device (SAD) insertion in spontaneously breathing morbidly obese patients.

Patients and methods: Thirty-eight morbidly obese patients with a body mass index 40–57 kg/m² who were scheduled for bariatric surgery under general anesthesia requiring tracheal intubation were randomly allocated to two groups receiving the different treatments: group S, saline was given intravenously, and group D, a bolus dose of DEX 1 μg/kg was administered intravenously over 10 mins, followed by intravenous DEX infusion at a rate of 0.5 μg/kg/h. Five percent sevoflurane was initially inhaled for anesthesia induction and then end-tidal expiratory sevoflurane concentration (ET_sev) was adjusted to a target value as to the modified Dixon’s up-and-down method. Patients’ response to SAD insertion was classified as “movement” or “no movement”. The average of the midpoints of all crossover points was defined as calculated sevoflurane EC₅₀ for successful SAD insertion. Furthermore, the probit regression analysis was used to determine sevoflurane end-tidal concentrations where 50% (EC₅₀) and 95% (EC₉₅) insertions of SAD were successful. After the observation was completed, flexible bronchoscope-guided intubation was performed through the SAD.

Results: The calculated sevoflurane EC₅₀ for successful SAD insertion was significantly lower in group D than in group S (1.75±0.32% vs 2.92±0.26%, p<0.001). By the probit regression analysis, EC₅₀ and EC₉₅ of sevoflurane for successful SAD insertion were 1.59% (95% CI, 1.22–1.90%) and 2.15% (95% CI, 1.86–3.84%) in group D, respectively, and 2.81% (95% CI, 2.35–3.29%) and 3.32% (3.02–6.74%) in group S.

Conclusion: When sevoflurane inhalational induction is performed in spontaneous breathing morbidly obese patients, intravenous DEX can reduce sevoflurane EC₅₀ for successful SAD insertion by about 40%.

Chinese Clinical Trial Registry: No. ChiCTR1800016868

The supraglottic airway device as first line of management in anticipated difficult mask ventilation in the morbidly obese

Background and Aims:

Supraglottic airway devices (SGAs) are used to rescue difficult and failed mask ventilation (DMV). We aimed to use the SGA as first-line device, prior to obtaining a definitive airway and to find any predictors of difficulty for the same, in the morbidly obese patients.

Material and Methods:

Obese surgical patients [body mass index (BMI) >35 kg/m²] were investigated. Difficulties with bag mask ventilation (MV) was graded using the following scale: MV-1, one anesthesiologist unassisted could achieve MV and maintain SpO₂>90%; MV-2, one additional anesthesiologist was needed to facilitate MV to achieve SpO₂> 90%; MV-3, two additional anesthesiologists were needed for this purpose; and MV-3P, when a supraglottic device was required to ventilate and maintain SpO₂ more than 90%. Parameters studied were age, gender, neck circumference (NC), BMI, STOPBANG score, and safe apnea time (SAT).

Results:

Logistic regression was performed for predictors of MV-3P; receiver operating characteristic curve was used to locate the best cut-off. Analysis of 834 morbidly obese patients revealed an incidence of MV 1/2/3/3-P as 16%/38%/27%/19%, respectively. DMV was associated with BMI ≥50 kg/m², NC ≥49.5 cm, and STOPBANG ≥6; P < 0.001. The mean SAT for a population with mean BMI 48 ± 8 kg/m² was 256 ± 66 s. The SAT showed inverse relation to BMI and NC. As per our results, the NC was the single most important predictor of MV-3P, with sensitivity 0.62 and specificity 0.85 at best cut-off 49.5 cm; P < 0.001.

Conclusion:

NC ≥49.5 cm is strongly associated with low SAT and need for SGA to achieve MV. SGA may provide safety for initial management following induction of anesthesia in this patient population.

Influence of lateral position and pneumoperitoneum on oropharyngeal leak pressure with two types of laryngeal mask airways

BACKGROUND

An important parameter to monitor adequate ventilation for laryngeal mask airway (LMA) is its oropharyngeal leak pressure (OLP). This study was designed to evaluate and compare the effect of lateral position and pneumoperitoneum on the OLP and ventilation efficiency between LMA™ Proseal (PLMA) and LMA™ Supreme (SLMA).

METHODS

Patients were randomized to receive either the PLMA or the SMLA. The OLP was assessed in both the supine position and the lateral position with or without pneumoperitoneum. Minute ventilation was increased to maintain normal EtCO₂ as far as possible. Ventilatory efficiency was scored as Class I (optimal, EtCO₂ 35-45 mmHg), Class II (suboptimal, EtCO₂ 45-55 mmHg) and Class III (poor, EtCO₂ >55 mmHg). Adverse events associated with LMA such as blood staining on the mask and sore throat were also recorded.

RESULTS

Within each group, the OLP was higher in the supine position than that in the lateral position with or without pneumoperitoneum (P < 0.01). However, pneumoperitoneum did not further decrease the OLP. The OLP with PLMA was higher compared with SLMA regardless of the position and pneumoperitoneum (P < 0.05 or 0.01). There was no significant difference in the number of patients in Class I/II/III for ventilation scores in the lateral position with pneumoperitoneum (83/7/2 in PLMA group and 76/14/2 in SLMA group, respectively). The incidence of adverse events was comparable in both groups.

CONCLUSION

Our data demonstrate that the PLMA has a higher OLP in comparison with the SLMA in the lateral position for laparoscopic surgery. Both devices provide comparably adequate ventilatory efficiency.

The Physiologically Difficult Airway

Airway management in critically ill patients involves the identification and management of the potentially difficult airway in order to avoid untoward complications. This focus on difficult airway management has traditionally referred to identifying anatomic characteristics of the patient that make either visualizing the glottic opening or placement of the tracheal tube through the vocal cords difficult. This paper will describe the physiologically difficult airway, in which physiologic derangements of the patient increase the risk of cardiovascular collapse from airway management. The four physiologically difficult airways described include hypoxemia, hypotension, severe metabolic acidosis, and right ventricular failure. The emergency physician should account for these physiologic derangements with airway management in critically ill patients regardless of the predicted anatomic difficulty of the intubation.

Comparison of the size 3 and size 4 ProSeal™ laryngeal mask airway in anesthetized, non-paralyzed women: a randomized controlled trial

PURPOSE

Based on experimental results, various authors have advocated a size 4 ProSeal™ laryngeal mask airway (PLMA) in preference to a size 3 PLMA for women given a neuromuscular blocking agent because the larger size provided a better airway seal. However, spontaneously breathing patients may be ventilated adequately with a lower seal pressure than that needed for mechanical ventilation. Therefore, a smaller size might be preferable as its reduced bulk possibly induces less mucosal damage in non-paralyzed patients.

METHODS

A total of 152 females undergoing general anesthesia for short outpatient gynecological surgeries were randomly allocated in equal numbers to insertion of a size 3 or 4 PLMA. The insertion time, success rate, seal pressure, hemodynamic variables, and complications, such as blood staining and sore throat, were evaluated.

RESULTS

The incidence of blood staining was lower with the size 3 PLMA compared to the size 4 PLMA (18 vs. 36 %; P = 0.028). Compared with the size 3 LMA, the size 4 PLMA resulted in higher fluctuations in both blood pressure (P = 0.003) and heart rate (P = 0.01). The insertion time was shorter with the size 3 PLMA (9 vs. 16 s; P < 0.001). The airway seal pressure with the size 3 PLMA, although lower than that of the size 4 PLMA (23 vs. 28 cmH2O; P = 0.001), was sufficient for spontaneous ventilation.

CONCLUSIONS

Due to the reduced incidence of mucosal injury and greater hemodynamic stability, the size 3 PLMA may be preferable to the size 4 PLMA for non-paralyzed females.

Airway management in obese patients

The well-known difficulties in airway management in obese patients are caused by obesity-related airways and respiratory changes. Anesthesiologists confront a number of troubles, including rapid oxygen desaturation, difficulty with laryngoscopy/intubation and mask ventilation, and increased susceptibility to the respiratory depressant effects of anesthetic drugs. Preoperative assessment of the airways in the obese should include examination of specific predictors of difficult mask ventilation other than those for difficult intubation. Difficulties in airway management are decreased after providing optimal preoxygenation and positioning ("ramped"). Other strategies may include availability of alternative airway management devices, including new video laryngoscopes that significantly improve the visualization of the larynx and thereby facilitate intubation. If awake intubation is mandatory, it may be performed with fibrobronchoscope after providing an adequate topical anesthesia and sedation with short-acting drugs, such as remifentanil. Succinylcholine for rapid sequence induction might be replaced by rocuronium where sugammadex is available for reversal. A complete reversal of neuromuscular block, measured by train-of-four monitoring, should be obtained before extubation, which requires a fully awake patient in the same position with airway equipment used for intubation.