Prevalence and risk factors of difficult mask ventilation: A systematic review and meta-analysis

STUDY OBJECTIVE

This meta-analysis aimed at identifying the risk factors for and their strengths in predicting difficult mask ventilation (MV) through a systematic approach.

DESIGN

Meta-analysis of observational studies.

SETTING

Operating room.

INTERVENTION

Airway- or patient-related risk factors for difficult MV reported in over 20% of eligible studies identified through literature review.

PATIENTS

Adults receiving anesthetic induction with requirement of MV.

MEASUREMENTS

Databases including EMBASE, MEDLINE, Google Scholar, and Cochrane Library were searched from inception to July 2022. The primary outcomes were the identification of commonly reported risk factors for MV and a comparison of their strengths in difficult MV prediction, while the secondary outcomes were the prevalence of difficult MV in the general population and those with obesity.

MAIN RESULTS

Meta-analysis of 20 observational studies involving 335,846 patients identified 13 risk factors with predictive strengths (all p < 0.05): neck radiation (OR = 5.0, five studies, n = 277,843), increased neck circumference (OR = 4.04, 11 studies, n = 247,871), obstructive sleep apnea (OSA) (OR = 3.61, 12 studies, n = 331,255), presence of beard (OR = 3.35, 12 studies, n = 295,443), snoring (OR = 3.06, 14 studies, n = 296,105), obesity (OR = 2.99, 11 studies, n = 278,297), male gender (OR = 2.76, 16 studies, n = 320,512), Mallampati score III-IV (OR = 2.36, 17 studies, n = 335,016), limited mouth opening (OR = 2.18, six studies, n = 291,795), edentulous (OR = 2.12, 11 studies, n = 249,821), short thyroid-mental distance (OR = 2.12, six studies, n = 328,311), old age (OR = 2, 11 studies, n = 278,750), and limited neck movement (OR = 1.98, nine studies, n = 155,101). The prevalence of difficult MV was 6.1% (16 studies, n = 334,694) and 14.4% (four studies, n = 1152) in the general population and those with obesity, respectively.

CONCLUSIONS

Our results demonstrated the strengths of 13 most common risk factors for predicting difficult MV, which may serve as an evidence-based reference for clinicians to incorporate into their daily practice.

Usefulness of Tulip Airway in Edentulous Elderly Patients

OBJECTIVE

Mask ventilation can be difficult in elderly edentulous patients. Various solutions have been proposed to address this challenge. This study assessed the use of a new airway-securing device called the Tulip Airway and investigated its application in simulated edentulous patients.

METHODS

This pilot study utilized a modified edentulous airway training mannequin and a high-performance simulator. Participants attempted to ventilate the edentulous mannequin using a Guedel oropharyngeal airway and face mask (M method) or the Tulip Airway (T method). Successful inflation of the mannequin model lung was confirmed visually. The time required for the insertion of the Tulip Airway was also assessed. A high-performance simulator was then used to compare ventilation volumes achieved using the M and T methods, and data subsequently analyzed.

RESULTS

In the edentulous mannequin, lung inflation was not achieved by any participants using the M method, but all were successful using the T method. Insertion time for the Tulip Airway was ∼8 seconds. Median ventilation volumes achieved using the high-performance simulator were higher for the T method (308 mL) compared with the M method (192 mL; P &lt; .05).

CONCLUSION

The results of this pilot study indicate that the Tulip Airway is an effective airway device for use in edentulous patients with difficult mask ventilation.

Submental Ultrasound Is Effective in Predicting Difficult Mask Ventilation but Not in Difficult Laryngoscopy

The goal of this study was to determine the utility of submental ultrasound parameters in distinguishing difficult airway management from easy airway management. Forty-one adult patients who underwent elective surgery under general anesthesia with endotracheal intubation from March to December 2018 were included. We used submental ultrasound to measure tongue base thickness (TBT) in the midsagittal plane and the distance between lingual arteries (DLA) in the transverse dimension. The primary outcome was difficult laryngoscopy, and the secondary outcome was difficult mask ventilation. Receiver operating characteristic curve analysis and logistic regression revealed no correlation between difficult laryngoscopy and SMUS measurements. Nevertheless, patients with difficult mask ventilation had significantly higher TBT (p = 0.009) and longer DLA (p = 0.010). After adjustment of confounding factors, increased TBT (>69.6 mm) was the sole independent predictor of difficult mask ventilation. The results indicated that SMUS is effective in predicting difficult mask ventilation but not difficult laryngoscopy.

Using gel for difficult mask ventilation on the bearded patients: a simulation-based study

The beard is a well-known cause of difficult mask ventilation due to excessive air leaks. Various techniques have been proposed to overcome this difficulty, such as applying a gel on the mask edge. Our objective was to determine whether the gel technique will improve ventilation and to assess the comfort of the provider. A randomized crossover design was conducted to assess the efficacy of gel in a bearded simulation model. Respiratory therapists (RT) were recruited by convenience sampling to hold the mask using a two-handed technique for a two-minute ventilation session. During the session, the ventilator provided a fixed Tidal Volume (TV) of 550 mL and a respiratory rate of 12 per minute, and the simulated model measured the received volumes. We compared the median TV and number of failed ventilation attempts with or without the gel. The comfort level while using the gel was assessed with constructed questions. We recruited 74 respiratory therapists working in Riyadh city. More than half of the participants had more than 5 years experience. The median tidal volume for standard mask ventilation without the gel was 283 mL [interquartile range (IQR) 224, 327], whereas that with the gel was 467 mL [451, 478], respectively (p < 0.01). The number of successful ventilations was recorded out of 24 breaths during the 2-min ventilation period for each technique; the proportion of successful ventilations increased significantly by 65% (95% CI 51-75%, p < 0.01) with the gel. In addition, only nine participants believed the technique was not comfortable, while the remaining individuals found it comfortable or natural. In our bearded simulation model, applying the gel significantly improved ventilation without negatively affecting comfort. Further studies and education are encouraged in the field of basic airway management.

Evaluation of super-obesity and super-super-obesity as risk factors for difficult intubation in patients undergoing bariatric surgery

BACKGROUND

Super-obesity is a serious disorder which requires bariatric surgery. The association of super-obesity and difficult intubation was not adequately established.

OBJECTIVES

To determine if super-obesity and super-super-obesity are associated with difficult intubation or not.

SETTING

University Hospital.

METHODS

A cohort of obese patients scheduled for bariatric surgery was prospectively recruited. Super-obesity and super-super-obesity were defined as body mass index ≥50 kg/m² and 60 kg/m², respectively. Intubation difficulty was assessed by 2 methods: (1) intubation difficulty scale; (2) number of intubation attempts. Risk factors for difficult intubation were recorded. Univariate and multivariate analysis for risk factors for difficult intubation and difficult mask ventilation were performed.

RESULTS

A total of 658 patients were enrolled in the study including 205 (31%) super-obese and 52 (8%) super-super-obese patients. Ninety-nine (15%) patients required more than 1 intubation attempt, while 215 (33%) patients had intubation difficulty scale ≥5. Ninety-four (14.4%) patients had mask ventilation of moderate difficulty, while only 2 (.3%) patients needed 2-person ventilation. The independent risk factors for difficult intubation using the two stated definitions were STOP-Bang and Mallampati score values. The independent risk factors for mask ventilation of moderate difficulty were STOP-Bang score, Mallampati score, and limited neck extension.

CONCLUSION

Within obese patients, neither super-obesity nor super-super-obesity was associated with difficult intubation or difficult mask ventilation. High STOP-Bang and Mallampati score are the independent factors for difficult intubation.

Utilization of apnea-hypopnea index as a novel predictive factor for difficult mask ventilation in the Chinese population under general anesthesia

Purpose

Difficult mask ventilation (DMV) is a potentially life-threatening situation that can arise during anesthesia. However, most clinical predictors of DMV are based on European and US populations. On the other hand, most predictive models consist of multiple factors and complicated assessments. Since obstructive sleep apnea (OSA) is among the most important risk factors associated with DMV, the apnea-hypopnea index (AHI) may play an important role in determining patient risk.The purpose of this study was to investigate the relationship between DMV and AHI, and to determine preoperative risk factors for DMV in Chinese patients.

Methods

A prospective cohort trial enrolled patients scheduled for elective surgery. After obtaining informed consent, patient demographic information was collected, and patients were tested with pre-operative polysomnography. The anesthesiologist who managed the airway graded the mask ventilation. The difficult mask ventilation was defined as the mask ventilation provided by an unassisted anesthesiologist without oral airway or other adjuvant. A logistic regression model was used to analyze the association between AHI and DMV.

Results

A total of 159 patients were analyzed. For both primary and secondary outcomes, the unadjusted and adjusted odds ratio for DMV showed significant increases by 5 AHI units. AHI, age, and the Mallampati classification were found to be independent predictive factors for DMV.

Conclusions

AHI is associated with DMV as a novel independent risk factor in Chinese patients. Along with age and Mallampati classification, AHI should be included in establishing a superior predictive strategy for DMV screening.

Trial registration

Chinese Clinical Trial Registry ChiCTR-DDD-17013076

Awake fiberoptic intubation with an epidural catheter in a morbidly obese patient

We report successful awake intubation in a morbidly obese patient (body mass index of 61.2) using an epidural catheter inserted through the external forceps channel of the fiberscope for delivery of local anesthetic. Direct application of local anesthetic to the pharyngolaryngeal area and proximal tracheal, through the use of a relatively firm epidural catheter. We conclude that awake intubation can be achieved by this method which spares the subsequent use of any sedative drugs.

Correlation of Neck Circumference with Difficult Mask Ventilation and Difficult Laryngoscopy in Morbidly Obese Patients: an Observational Study

PURPOSE

Mask ventilation and laryngoscopy can be challenging in morbidly obese patients because of excessive fat tissue. There are studies suggesting that neck circumference is associated with difficult mask ventilation, difficult laryngoscopy, and difficult intubation. The primary aim of our study is to evaluate predictive value of neck circumference for difficult mask ventilation and difficult laryngoscopy in female and male morbidly obese patients separately.

METHODS

This observational cross-sectional study was performed in the period between March 2015 and December 2015. One hundred and twenty (37 male and 83 female) patients undergoing elective surgery were included. Neck circumference, BMI, Mallampati scores, neck movements, dentition, upper lip bite test, breast, thorax, waist, hip circumferences, mouth opening, and sternomental and thyromental distances were evaluated preoperatively. Mask ventilation was graded using four-grade classification. Laryngoscopy was evaluated by Cormack Lehane score.

RESULTS

The incidence of difficult mask ventilation was 13.5% in male and 3.6% in female patients. Mouth opening ≤ 6.5 cm and inadequate flexion were found as significant predictors for difficult mask ventilation in male patients. The incidence of difficult laryngoscopy was 10.8% in male and 4.8% in female patients. Mallampati score > II was found as a significant predictor for difficult laryngoscopy in both male and female patients. Sternomental distance ≤ 16 cm and inadequate flexion were also significant predictors for difficult laryngoscopy in male patients. Neck circumference was not found statistically significant predictor for difficult mask ventilation and laryngoscopy in morbidly obese patients in our study.

CONCLUSION

Neck circumference is not a statistically significant predictor for difficult mask ventilation and laryngoscopy in morbidly Turkish obese male and female patients.

CLINICAL TRIALS REGISTRATION NUMBER

NCT02589015.

Obstructive sleep apnea as a risk factor associated with difficult airway management - A narrative review

STUDY OBJECTIVE

The association between obstructive sleep apnea (OSA) and difficult airway had been studied in various clinical trials but the relationship between the two conditions has not been clearly established. The objective of this narrative review is to determine if OSA is a risk factor associated with difficult airway.

DESIGN

The OVID Medline in process, Medline (vis Pub Med), EMBASE, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, Web of Science and SCOPUS were searched up to April 2016 using specific keywords. Inclusion criteria were: [1] airway management in patients with a diagnosis of OSA, [2] comparison of airway management between OSA and non-OSA patients, [3] publications or abstracts in the English language. The incidence of difficult airway between OSA and non-OSA patients was compared using Chi-square analysis or Fisher's exact test.

MAIN RESULTS

Ten studies were included in the final review. Overall, the incidence of difficult tracheal intubation was higher in OSA patients versus non-OSA patients [56/386 (14.5%) vs. 69/897 (7.7%); P=0.0002]. OSA patients also have a higher incidence of difficult mask ventilation [115/4626 (2.5%) vs. 471/64,684 (0.7%); P<0.0001]. Compared to non-OSA patients, OSA was not associated with difficulty in the use of a supraglottic airway (SGA) device [10/663 (1.5%) vs. 162/15,171 (1.1%); P=0.38]. No studies compared difficult surgical airway in OSA and non-OSA patients.

CONCLUSIONS

OSA was found to be a risk factor associated with difficult tracheal intubation and difficult mask ventilation. There was no association between OSA and difficult SGA use.

Nasal mask ventilation is better than face mask ventilation in edentulous patients

Background and Aims:

Face mask ventilation of the edentulous patient is often difficult as ineffective seating of the standard mask to the face prevents attainment of an adequate air seal. The efficacy of nasal ventilation in edentulous patients has been cited in case reports but has never been investigated.

Material and Methods:

Consecutive edentulous adult patients scheduled for surgery under general anesthesia with endotracheal intubation, during a 17-month period, were prospectively evaluated. After induction of anesthesia and administration of neuromuscular blocker, lungs were ventilated with a standard anatomical face mask of appropriate size, using a volume controlled anesthesia ventilator with tidal volume set at 10 ml/kg. In case of inadequate ventilation, the mask position was adjusted to achieve best-fit. Inspired and expired tidal volumes were measured. Thereafter, the face mask was replaced by a nasal mask and after achieving best-fit, the inspired and expired tidal volumes were recorded. The difference in expired tidal volumes and airway pressures at best-fit with the use of the two masks and number of patients with inadequate ventilation with use of the masks were statistically analyzed.

Results:

A total of 79 edentulous patients were recruited for the study. The difference in expiratory tidal volumes with the use of the two masks at best-fit was statistically significant (P = 0.0017). Despite the best-fit mask placement, adequacy of ventilation could not be achieved in 24.1% patients during face mask ventilation, and 12.7% patients during nasal mask ventilation and the difference was statistically significant.

Conclusion:

Nasal mask ventilation is more efficient than standard face mask ventilation in edentulous patients.