Abstract
Background: Some anesthetized patients present with expiratory airway obstruction (EAO) during mask ventilation (MV). EAO may occur more frequently among edentulous patients for whom a firmer grip of the mask and the mandible is needed to avoid gas leakage. We compared EAO grades before and after denture removal and identified predictors of EAO during MV in edentulous patients. Methods: One hundred and eight denture-wearing edentulous patients were anesthetized, their mouths were wrapped with film, their nasal masks and mandibles were held with two hands, and their lungs were ventilated in a pressure-controlled mode. Their dentures were subsequently removed, mouths were re-wrapped, and nasal MV was reapplied. EAO was graded based on capnography waveforms as follows: Grade I, normal waveform (no obstruction); II, loss of the alveolar plateau of the waveform (partial obstruction); and III, no waveform (total obstruction). EAO grades were compared before and after denture removal. Predictive demographic variables for occurrence of total EAO were identified using a multivariate analysis. Results: The proportions of Grades I, II, and III were 43.5%, 26.9%, and 29.6% when dentures were worn and 35.2%, 15.7%, and 49.1%, respectively, when dentures were removed. A significant difference was observed in EAO grades before and after denture removal (P = 0.000034). Age ≥ 75 years (adjusted odds ratio 3.41; 95% confidence interval 1.31 - 8.87; P = 0.012) and body mass index ≥ 25 kg/m2 (adjusted odds ratio 2.61; 95% confidence interval 1.07 - 6.40; P = 0.036) were independently associated with an increased incidence of total EAO in patients with their dentures removed. Conclusion: Denture removal impaired expiratory upper airway patency in edentulous patients, particularly in older or obese patients, during MV.
Highlights
Mask ventilation (MV) is a pivotal procedure used to deliver oxygen during the induction of general anesthesia before a secure airway with a tracheal tube or supraglottic airway device can be established
Five patients who showed inspiratory airway obstruction and required an oral airway device during the initial MV with two-handed mask holding with the head tilt when wearing dentures were excluded for not fulfilling the inclusion criteria
We demonstrated that edentulous patients with their dentures removed had a higher incidence of total expiratory airway obstruction (EAO), qualitatively assessed by capnography waveforms and the occurrence of breath stacking, than that seen in the patients before denture removal during MV at the induction of anesthesia
Summary
Mask ventilation (MV) is a pivotal procedure used to deliver oxygen during the induction of general anesthesia before a secure airway with a tracheal tube or supraglottic airway device can be established. The velopharynx may be occluded during expiration [3] In this case, when the mask is tightly seated onto the face and the mouth is closed, the soft palate functions as a one-way check valve during expiration, leading to expiratory airway obstruction (EAO). Methods: One hundred and eight denture-wearing edentulous patients were anesthetized, their mouths were wrapped with film, their nasal masks and mandibles were held with two hands, and their lungs were ventilated in a pressure-controlled mode. Their dentures were subsequently removed, mouths were re-wrapped, and nasal MV was reapplied. Conclusion: Denture removal impaired expiratory upper airway patency in edentulous patients, in older or obese patients, during MV
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