Airway events in obese vs. non-obese elective surgical patients: a cross-sectional observational study

Videolaryngoscopy vs. direct laryngoscopy in class 2 and 3 obesity: a systematic review, meta-analysis and trial sequential analysis of randomised controlled trials

INTRODUCTION

The 7th National Audit Project of the Royal College of Anaesthetists revealed an increase in rates of tracheal intubation over the last decade, partially contributed to by the rise in people living with obesity. Notably, airway and respiratory complications were over-represented in patients living with class 2 or 3 obesity (BMI ≥ 35 kg.m-2). Hence, it is timely to evaluate if videolaryngoscopy might improve tracheal intubation-related outcomes when compared with direct laryngoscopy in this high-risk patient group.

METHODS

We conducted a systematic review and meta-analysis of randomised controlled trials published in the last 15 years. We searched five databases for trials comparing videolaryngoscopy with direct laryngoscopy in adult patients living with class 2 or 3 obesity undergoing elective general surgery. Primary outcomes were the incidence of failed tracheal intubation; hypoxaemia; and first attempt tracheal intubation failure. Secondary outcomes were glottic visualisation; time to tracheal intubation; incidence of sore throat; and intubation difficulty scale.

RESULTS

We included 10 trials with 955 patients, of whom 481 received videolaryngoscopy and 474 direct laryngoscopy. Videolaryngoscopy significantly reduced failed tracheal intubation (relative risk (95%CI) 0.15 (0.05-0.35), p < 0.001, nine studies); hypoxaemia (relative risk (95%CI) 0.21 (0.10-0.43), p < 0.001, seven studies); and first attempt failure (relative risk (95%CI) 0.44 (0.25-0.76), p = 0.004, seven studies). While glottic visualisation was also significantly improved, there was no significant difference in time to tracheal intubation, incidence of sore throat or intubation difficulty scale.

CONCLUSIONS

In patients living with class 2 or 3 obesity, videolaryngoscopy significantly reduced failed tracheal intubation incidence, first-attempt failure incidence, incidence of hypoxaemia and poor glottic visualisation. Patients living with class 2 or 3 obesity are likely to benefit from the use of videolaryngoscopy compared with direct laryngoscopy.

Videolaryngoscopy vs. direct laryngoscopy in orotracheal intubation in obese critical patients: Systematic review and meta-analysis

OBJECTIVE

To determine whether the use of videolaryngoscopy (VL) is more effective than direct laryngoscopy (DL) for orotracheal intubation in obese patients.

DESIGN

This is a systematic review and meta-analysis.

SETTING

A comprehensive search was conducted in five databases for studies published up to December 26, 2023, using a PICO strategy. Fifteen studies were identified for quantitative analysis and included in our meta-analysis.

PARTICIPANTS

The participants of the included primary studies (obese patients).

INTERVENTIONS

Orotracheal intubation with videolaryngoscopy or direct laryngoscopy.

MAIN VARIABLES OF INTEREST

Videolaryngoscopy, direct laryngoscopy, intubation time, first--pass success rate, minor complications.

RESULTS

No significant differences were found in intubation time between VL and DL in obese patients (MD: -4.84; 95% CI: -13.49 to 3.80; I2: 90%). In the subgroup analysis, the Airtaq technique showed a significant difference in intubation time compared to the Macintosh technique (MD: -25.29; 95% CI: -49.17 to -1.38; I2: 95%). However, no significant differences were observed in the first--pass success rate (OR: 1.58; 95% CI: 0.77-3.23; I2: 33%) or in complications such as pain (OR: 1.15; 95% CI: 0.75-1.75; I2: 0%) and voice changes (OR: 0.76; 95% CI: 0.46-1.26; I2: 0%) between the two methods.

CONCLUSION

There are no significant differences in intubation time, first--pass success rate, or complications between VL and DL in obese critical patients.

Ultrasound Evaluation of Gastric Emptying and Comparison with Patient-Reported Risk Factors in Elective Surgical Patients

Background/Objectives: Despite standard preoperative fasting guidelines, residual gastric content can persist in some patients, increasing the risk of aspiration pneumonitis. Multiple patient-specific factors may predict gastric content retention, but their predictive accuracy is limited. We hypothesized that ultrasound would more reliably identify residual gastric content compared to a comprehensive questionnaire and aimed to determine the most practical approach for risk assessment in elective surgical patients. Methods: We conducted a prospective, observational study in adult patients scheduled for elective surgery at a single center. All participants adhered to an 8 h fasting period. The primary outcome was the incidence of a "full stomach" on ultrasound. Secondary outcomes included the Perlas risk classification, comparisons of established volume estimation formulas, correlations with self-reported fasting duration, agreement between questionnaire-based predictions and ultrasound findings, and the time efficiency of each method. Multivariable logistic regression and Cohen's kappa were used for analyses. Results: Data from 404 patients were analyzed. Despite prolonged fasting, 16.3% had a full stomach by ultrasound, suggesting incomplete gastric emptying. Early satiety and cholelithiasis significantly predicted a full stomach; prolonged fasting duration and female sex were protective. Questionnaire-based predictions demonstrated fair agreement with ultrasound (kappa = 0.327). The Michiko formula often yielded negative volumes, highlighting limitations in volume estimations. Ultrasound examination (3 min median) was faster than questionnaire completion (5 min). Conclusions: Ultrasound accurately detects residual gastric content, outperforming questionnaire-based assessments. Integrating it into routine preoperative evaluation may improve patient safety, although research is needed to refine volume estimation formulas and expand feasibility for patients with positioning limitations.

Universal C-MAC® videolaryngoscope use in adult patients: a single-centre experience

Universal use of Storz C-MAC® videolaryngoscopes was implemented for adult tracheal intubations in the operating theatres, intensive care unit and emergency department at Royal United Hospitals Bath NHS Foundation Trust in 2017. We report data from 1099 intubations from March 2020 to March 2022, collected contemporaneously and anonymously using a smartphone app, representing an estimated 18% of intubations in operating theatres and 30% of intubations in other locations during this period. Intubation success was 100%. The first-pass success rate was 87.3% overall: 87% with a Macintosh videolaryngoscope, 92% with a hyperangulated videolaryngoscope and 81% for users with ≤ 20 previous uses. First-pass success without complications was 87% overall: 87% in operating theatres (836/962), 93% in the emergency department (38/41) and 83% in the intensive care unit (73/88). Complications occurred during 0.6% of intubations: 0/962 in operating theatres and 7/137 in non-theatre locations. The rate of complications was unaltered by blade type (Macintosh 5/994 vs. hyperangulated 2/105, p = 0.14); intubator experience with the device (≤ 20 previous clinical uses 2/260 vs. > 20 previous uses 5/832, p = 0.67) and use of airborne personal protective equipment (PPE 6/683 vs. no-PPE 1/410, p = 0.27). Complication rates increased outside theatres (theatres 0/963 vs. non-theatre 7/136, p < 0.001) and during rapid sequence induction (RSI 6/379 (1.6%) vs. non-RSI 1/720 (0.1%), p = 0.008).

Airway and respiratory complications during anaesthesia and associated with peri-operative cardiac arrest as reported to the 7th National Audit Project of the Royal College of Anaesthetists

The 7th National Audit Project (NAP7) of the Royal College of Anaesthetists studied complications of the airway and respiratory system during anaesthesia care including peri-operative cardiac arrest. Among 24,721 surveyed cases, airway and respiratory complications occurred commonly (n = 421 and n = 264, respectively). The most common airway complications were: laryngospasm (157, 37%); airway failure (125, 30%); and aspiration (27, 6%). Emergency front of neck airway was rare (1 in 8370, 95%CI 1 in 2296-30,519). The most common respiratory complications were: severe ventilation difficulty (97, 37%); hyper/hypocapnia (63, 24%); and hypoxaemia (62, 23%). Among 881 reports to NAP7 and 358 deaths, airway and respiratory complications accounted for 113 (13%) peri-operative cardiac arrests and 32 (9%) deaths, with hypoxaemia as the most common primary cause. Airway and respiratory cases had higher and lower survival rates than other causes of cardiac arrest, respectively. Patients with obesity, young children (particularly infants) and out-of-hours care were overrepresented in reports. There were six cases of unrecognised oesophageal intubation with three resulting in cardiac arrest. Of these cases, failure to correctly interpret capnography was a recurrent theme. Cases of emergency front of neck airway (6, approximately 1 in 450,000) and pulmonary aspiration (11, approximately 1 in 25,000) leading to cardiac arrest were rare. Overall, these data, while distinct from the 4th National Audit Project, suggest that airway management is likely to have become safer in the last decade, despite the surgical population having become more challenging for anaesthetists.

Safety, Efficacy, and Ease of Insertion of Gnana Laryngeal Airway (GLA-4): A Prospective Clinical Study Utilizing the Unique Laryngeal Mask Airway With a Suction Tubing

INTRODUCTION

Utilizing laryngeal mask airways to maintain patients' airways is advantageous because it enables the anesthesiologist to keep the patient spontaneously inhaling and is less traumatic to the airway than intubation. Newer designs such as the Gnana laryngeal mask airway design permit real-time suctioning while the mask is on a patient.

METHODS

This is a prospective observational study of the efficacy of Gnana laryngeal airway 4 (GLA-4) in 50 patients undergoing colonoscopy. Induction and maintenance of anesthesia were provided with propofol; GLA-4 was applied to secure the airway; and correct placement was verified.

RESULTS

Fifty patients were included in the study (44% female, 56% male, mean age: 56.5 years, mean BMI: 33.3). Twelve patients were assigned American Society of Anesthesiologists (ASA) class 2, and 38 were assigned ASA class 3. The first attempt of GLA-4 insertion was successful in 47 patients, and two attempts were required for the successful placement of the GLA-4 in two patients. The successful placement was not achieved in one patient. The average time to successful insertion was 27.1 ± 3.9s. The average volume of oropharyngeal secretions suctioned through the suction catheter was 9.96 ± 2.31 mL. No intraoperative or postoperative complications occurred in the 50 patients. There were no reports of sore throat, hoarseness, dysphagia, or cough immediately postop.

CONCLUSION

GLA-4 can be inserted safely with adequate periglottic occlusion. This laryngeal mask is unique and desirable due to its ability to evacuate oropharyngeal secretions while in place to prevent laryngospasm. To establish the role of GLA-4 in broader clinical situations, additional clinical trials and studies are required.

Non-theatre emergency airway management: a multicentre prospective observational study

Emergency airway management events are common, unpredictable and associated with high complication rates. This multicentre prospective observational study across eight acute NHS hospitals in southeast England reports the incidence and nature of non-theatre emergency airway management events. Data were collected from non-theatre emergency airway management, including adverse events, over a continuous 28-day window, and recorded on an electronic case report form. Events were classified according to type (advanced airway; simple airway; and cardiac arrest). A total of 166 events were recorded, with 111 advanced airway events involving tracheal intubation or tracheostomy management. Senior personnel with three or more years of airway management experience were present for 105/111 (95%) advanced airway management episodes. There was a significant reduction in consultant or equivalent presence out-of-hours (21/64, 33%) vs. in-hours (34/47, 72%) (p < 0.001). We found high utilisation of videolaryngoscopy (95/106, 90%) and universal use of capnography for all advanced airway management events. This was lower during cardiac arrest when videolaryngoscopy was used in 11/16 (69%) of tracheal intubations and capnography in 21/32 (66%) of all cardiac arrest episodes. Adverse outcomes during advanced airway management (excluding during cardiac arrest) occurred in 53/111 (48%) episodes, including hypoxia (desaturation to Sp O2 < 80% in 14/111, 13%) and hypotension (systolic blood pressure < 80 mmHg in 27/111, 25%). Adverse outcomes were not associated with time of day or experience level of airway practitioners. We conclude that there is a disparity between consultant presence for advanced airway interventions in- and out-of-hours; high utilisation of videolaryngoscopy and capnography, especially for advanced airway interventions; and a high incidence of hypotension and hypoxaemia, including critical values, during non-theatre airway management.

Preintubation Machine-Delivered Pressure Support Ventilation With Positive End-Expiratory Pressure Versus Manual Bag-Mask Ventilation for Oxygenation in Overweight and Obese Patients: A Randomized, Pilot Study

BACKGROUND

Noninvasive positive pressure ventilation (NIPPV) maintains mean airway pressures well, and its usability for preoxygenation is well described. Anesthesia machine-delivered NIPPV-based preoxygenation has recently been evaluated against the traditional manual bag-mask ventilation (BMV). The efficiency of such a technique over the traditional one is yet to be established well. The present study evaluated the feasibility of machine-delivered preoxygenation using pressure support ventilation (PSV) with positive end-expiratory pressure (PEEP) and compared the effectiveness with BMV.

METHODS

Thirty overweight and obese adults belonging to the American Society of Anesthesiologist's physical status I-II were randomized to receive PSV+PEEP or BMV for preintubation preoxygenation targeted to a fraction of expired oxygen (FeO2) of 85% and 90% or for a maximum period of five minutes, whichever came first. Postintubation, the patient was observed for the time taken until 1% desaturation without ventilation. Arterial blood gases, respiratory variables, FeO2 achieved, and different times were collected and compared.

RESULTS

The baseline characteristics and arterial blood gases were similar between the two groups. The PSV+PEEP group had consistent and favorable tidal volume and airway pressure delivery. The difference in time to reach a FeO2 of 85% between the two groups was not statistically different. Only two patients achieved a FeO2 of 90% in the PSV+PEEP group versus none in the BMV group. However, partial pressure of oxygen at 1% desaturation (217.42±109.47 versus 138.073±71.319 mmHg, p 0.0259) was higher in the PSV+PEEP group. Similarly, the time until 1% desaturation was significantly prolonged in the PSV+PEEP group (206.6±76.952 versus 140.466±54.245 seconds, p 0.0111).

CONCLUSION

The present pilot study findings indicate that preintubation machine-delivered PSV+PEEP-based preoxygenation is feasible and might be more effective than traditional BMV in overweight and obese patients.

Lung-protective ventilation during Trendelenburg pneumoperitoneum surgery: A randomized clinical trial

Study objective To assess the effects of a protective ventilation strategy during Trendelenburg pneumoperitoneum surgery on postoperative oxygenation.

DESIGNS

Parallel-group, randomized trial.

SETTING

Operating room of a university hospital, Italy.

PATIENTS

Morbidly obese patients undergoing Trendelenburg pneumoperitoneum gynaecological surgery.

INTERVENTIONS

Participants were randomized to standard (SV: tidal volume = 10 ml/kg of predicted body weight, PEEP = 5 cmH₂O) or protective (PV: tidal volume = 6 ml/kg of predicted body weight, PEEP = 10 cmH₂O, recruitment maneuvers) ventilation during anesthesia.

MEASUREMENTS

Primary outcome was PaO₂/FiO₂ one hour after extubation. Secondary outcomes included day-1 PaO₂/FiO₂, day-2 respiratory function and intraoperative respiratory/lung mechanics, assessed through esophageal manometry, end-expiratory lung volume (EELV) measurement and pressure-volume curves.

MAIN RESULTS

Sixty patients were analyzed (31 in SV group, 29 in PV group). Median [IqR] tidal volume was 350 ml [300-360] in PV group and 525 [500-575] in SV group. Median PaO₂/FiO₂ one hour after extubation was 280 mmHg [246-364] in PV group vs. 298 [250-343] in SV group (p = 0.64). Day-1 PaO₂/FiO_2, day-2 forced vital capacity, FEV-1 and Tiffenau Index were not different between groups (all p > 0.10). Intraoperatively, 59% of patients showed complete airway closure during pneumoperitoneum, without difference between groups: median airway opening pressure was 17 cmH₂O. In PV group, airway and transpulmonary driving pressure were lower (12 ± 5 cmH₂O vs. 17 ± 7, p < 0.001; 9 ± 4 vs. 13 ± 7, p < 0.001), PaCO₂ and respiratory rate were higher (48 ± 8 mmHg vs. 42 ± 12, p < 0.001; 23 ± 5 breaths/min vs. 16 ± 4, p < 0.001). Intraoperative EELV was similar between PV and SV group (1193 ± 258 ml vs. 1207 ± 368, p = 0.80); ratio of tidal volume to EELV was lower in PV group (0.45 ± 0.12 vs. 0.32 ± 0.09, p < 0.001).

CONCLUSIONS

In obese patients undergoing Trendelenburg pneumoperitoneum surgery, PV did not improve postoperative oxygenation nor day-2 respiratory function. PV was associated with intraoperative respiratory mechanics indicating less injurious ventilation. The high prevalence of complete airway closure may have affected study results.

TRIAL REGISTRATION

Prospectively registered on http://clinicaltrials.govNCT03157479 on May 17th, 2017.

Risk patterns of consecutive adverse events in airway management: a Bayesian network analysis

BACKGROUND

Minor adverse airway events play a pivotal role in the safety of airway management. Changes in airway management strategies can reduce such events, but the broader impact on airway management remains unclear.

METHODS

Minor, frequently occurring adverse airway events were audited before and after implementation of changes to airway management strategies. We used two Bayesian networks to examine conditional probabilities of subsequent airway events and to compute the likelihood of certain events given that certain previous events occurred.

RESULTS

Independent of sex, age, and American Society of Anesthesiologists physical status, targeted changes to airway management strategies reduced the risk of a first event. Obese patients were an exception, in whom no risk reduction was achieved. Frequently occurring event sequences were identified, for example the most likely event to follow difficult bag-mask ventilation was a Cormack-Lehane grade ≥3, with a risk of 14.3% (95% credible interval [CI], 11.4-17.2%). An impact of the targeted changes was detected on the likelihood of some event sequences, for example the likelihood of no consecutive event after a tracheal tube-related event increased from 43.3% (95% CI, 39.4-47.6%) to 56.4% (95% CI, 52.0-60.5%).

CONCLUSIONS

Identification of risk patterns and typical structures of event sequences provides a clinically relevant perspective on airway incidents. It further provides a means to quantify the impact of targeted airway management changes. These targeted changes can influence some event sequences, but overall, the benefit results from the cumulative effect of improvements in multiple events. Targeted airway management changes with knowledge of risk patterns and event sequences can potentially further improve patient safety in airway management.

CLINICAL TRIAL REGISTRATION

NCT02743767.

Apnoeic oxygenation in morbid obesity: a randomised controlled trial comparing facemask and high-flow nasal oxygen delivery

BACKGROUND

Obesity is a risk factor for airway-related incidents during anaesthesia. High-flow nasal oxygen has been advocated to improve safety in high-risk groups, but its effectiveness in the obese population is uncertain. This study compared the effect of high-flow nasal oxygen and low-flow facemask oxygen delivery on duration of apnoea in morbidly obese patients.

METHODS

Morbidly obese patients undergoing bariatric surgery were randomly allocated to receive either high-flow nasal (70 L min^-1) or facemask (15 L min^-1) oxygen. After induction of anaesthesia, the patients were apnoeic for 18 min or until peripheral oxygen saturation decreased to 92%.

RESULTS

Eighty patients were studied (41 High-Flow Nasal Oxygen, 39 Facemask). The median apnoea time was 18 min in both the High-Flow Nasal Oxygen (IQR 18-18 min) and the Facemask (inter-quartile range [IQR], 4.1-18 min) groups. Five patients in the High-Flow Nasal Oxygen group and 14 patients in the Facemask group desaturated to 92% within 18 min. The risk of desaturation was significantly lower in the High-Flow Nasal Oxygen group (hazard ratio=0.27; 95% confidence interval [CI], 0.11-0.65; P=0.007).

CONCLUSIONS

In experienced hands, apnoeic oxygenation is possible in morbidly obese patients, and oxygen desaturation did not occur for 18 min in the majority of patients, whether oxygen delivery was high-flow nasal or low-flow facemask. High-flow nasal oxygen may reduce desaturation risk compared with facemask oxygen. Desaturation risk is a more clinically relevant outcome than duration of apnoea. Individual physiological factors are likely to be the primary determinant of risk rather than method of oxygen delivery.

CLINICAL TRIAL REGISTRATION

NCT03428256.

Aerosol precautions and airway complications: a national prospective multicentre cohort study

The perceived risk of transmission of aerosolised viral particles from patients to airway practitioners during the COVID-19 pandemic led to the widespread use of aerosol precautions, including personal protective equipment and modifications to anaesthetic technique. The risk of these aerosol precautions on peri-operative airway complications has not been assessed outside of simulation studies. This prospective, national, multicentre cohort study aimed to quantify this risk. Adult patients undergoing general anaesthesia for elective or emergency procedures over a 96-hour period were included. Data collected included use of aerosol precautions by the airway practitioner, airway complications and potential confounding variables. Mixed-effects logistic regression was used to assess the risk of individual aerosol precautions on overall and specific airway complications. Data from 5905 patients from 70 hospital sites were included. The rate of airway complications was 10.0% (95%CI 9.2-10.8%). Use of filtering facepiece class 2 or class 3 respirators was associated with an increased risk of airway complications (odds ratio 1.38, 95%CI 1.04-1.83), predominantly due to an association with difficult facemask ventilation (odds ratio 1.68, 95%CI 1.09-2.61) and desaturation on pulse oximetry (odds ratio 2.39, 95%CI 1.26-4.54). Use of goggles, powered air-purifying respirators, long-sleeved gowns, double gloves and videolaryngoscopy were not associated with any alteration in the risk of airway complications. Overall, the use of filtering facepiece class 2 or class 3 respirators was associated with an increased risk of airway complications, but most aerosol precautions used during the COVID-19 pandemic were not.