The incidence and risk factors of difficult mask ventilation.
ABSTRACT The ability to ventilate and oxygenate a patient using a bag-mask breathing system may be lifesaving in the case of failure of the initial intubation attempt. In this study, we aimed to determine the incidence of difficult mask ventilation (DMV) and to find preoperative risk factors for this procedure.
Based on methods used for overcoming some difficulties with bag-mask ventilation (MV), classification has been made into four categories: easy MV, awkward MV, difficult MV, and impossible MV. A univariate analysis was performed to identify potential risk factors predicting DMV, followed by a stepwise forward binary logistic regression, and the odds ratio and 95% confidence interval were calculated.
A total of 576 patients were studied. Incidence of easy MV, awkward MV, and difficult MV were found to be 75.5% (n = 435), 16.7% (n = 96), and 7.8% (n = 45), respectively. Height, weight, age, male gender, increased Mallampati class, history of snoring, lack of teeth, and beard were found to be DMV risk factors (P < 0.05). Using a multivariate analysis, Mallampati class 4, male, history of snoring, age, and weight were found to be significantly associated with DMV. Although the incidence of DMV in general was 7.8% (n = 45), the incidence of DMV among patients with difficult intubation (n = 123) was found to be 15.5% (n = 19).
Mallampati class 4, male patients, history of snoring, increasing age, and increasing weight were found to be risk factors for DMV in our study.
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ABSTRACT: Background Morbidly obese patients are more prone to desaturation of arterial blood during apnea with induction of anesthesia than are non-obese. This study aimed to assess the effect of low-pressure continuous positive airway pressure (CPAP) with pressure support ventilation (PSV) during pre-oxygenation on partial oxygen pressure in arterial blood (PaO2) immediately after tracheal intubation (post-intubation PaO2).Methods Forty-four adult patients scheduled for laparoscopic gastric bypass surgery were pre-oxygenated with 80% O2 for 2 min, randomized either to CPAP 5 cm H2O + PSV 5 cm H2O (CPAP/PSV, n = 22) or neutral-pressure breathing without CPAP/PSV (control, n = 22). Anesthesia was induced in a rapid-sequence protocol and the trachea was intubated without prior mask ventilation. Arterial blood gases were measured before pre-oxygenation, before induction of anesthesia, and immediately following intubation, before the first positive pressure breath.ResultsAfter pre-oxygenation, partial carbondioxide pressure was significantly lower in the CPAP/PSV group (4.9 ± 0.5 kPa), (mean ± standard deviation) than in the control group (5.2 ± 0.7 kPa) (P = 0.025). Post-preoxygenation PaO2 did not differ between the groups, but post-intubation PaO2 was significantly higher in the CPAP/PSV group (32.2 ± 4.1 kPa) than in the control group (23.8 ± 8.8 kPa) (P < 0.001). In the control group, nadir oxygen saturation was lower (median 98%, range 83–99%) than in the CPAP/PSV group (median 99%, range 97–99%, P = 0.011).Conclusions In morbidly obese patients, low-pressure CPAP combined with low-pressure PSV during pre-oxygenation resulted in better oxygenation, compared with neutral-pressure breathing, and prevented desaturation episodes.Acta Anaesthesiologica Scandinavica 05/2014; 58(6). DOI:10.1111/aas.12317 · 2.31 Impact Factor
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ABSTRACT: Background Difficult Mask Ventilation (DMV), is a situation in which it is impossible for an unassisted anesthesiologist to maintain oxygen saturation >90% using 100% oxygen and positive pressure ventilation to prevent or reverse signs of inadequate ventilation during mask ventilation. The incidence varies from 0.08 - 15%. Patient-related anatomical features are by far the most significant cause. We analyzed data from an obese surgical population (BMI> 30 kg/m (2)) to identify specific risk and predictive factors for DMV. Methods Five hundred and fifty seven obese patients were identified from a database of 1399 cases associated with preoperative airway examinations where mask ventilation was attempted. Assessment of mask ventilation in this group was stratified by a severity score (0-3), and a step-wise selection method was used to identify independent predictors. The area under the curve of the receiver-operating-characteristic was then used to evaluate the model's predictive value. Adjusted odds ratios and their 95% confidence intervals were also calculated. Results DMV was observed in 80/557 (14%) patients. Three independent predictive factors for DMV in obese patients were identified: age 49 years, short neck, and neck circumference 43 cm. In the current study th sensitivity for one factor is 0.90 with a specificity 0.35. However, the specificity increased to 0.80 with inclusion of more than one factor. Conclusion According to the current investigation, the three predictive factors are strongly associated with DMV in obese patients. Each independent risk factor alone provides a good screening for DMV and two factors substantially improve specificity. Based on our analysis, we speculate that the absence of at least 2 of the factors we identified might have a significant negative predictive value and can reasonably exclude DMV, with a negative likelihood ratio 0.81.10/2014; 3:239. DOI:10.12688/f1000research.5471.1
Article: Approaches to manual ventilation.[Show abstract] [Hide abstract]
ABSTRACT: Manual ventilation is a basic skill that involves airway assessment, maneuvers to open the airway, and application of simple and complex airway support devices and effective positive-pressure ventilation using a bag and mask. An important part of manual ventilation is recognizing its success and when it is difficult or impossible and a higher level of support is necessary to sustain life. Careful airway assessment will help clinicians identify what and when the next step needs to be taken. Often simple airway maneuvers such as the head tilt/chin lift and jaw thrust can achieve a patent airway. Appropriate use of airway adjuncts can further aid the clinician in situations in which airway maneuvers may not be sufficient. Bag-mask ventilation (BMV) plays a vital role in effective manual ventilation, improving both oxygenation and ventilation as well as buying time while preparations are made for endotracheal intubation. There are, however, situations in which BMV may be difficult or impossible. Anticipation and early recognition of these situations allows clinicians to quickly make adjustments to the method of BMV or to employ a more advanced intervention to avoid delays in establishing adequate oxygenation and ventilation.Respiratory care 06/2014; 59(6):810-24. DOI:10.4187/respcare.03060 · 1.84 Impact Factor