European Society of Anaesthesiologists; 8th Annual Meeting with the Austrian International Congress; Vienna, Austria, 1-4 April 2000
Background and goal of study: Difficult mask ventilation may cause significant morbidity and mortality. However, no preoperative physical examination has been shown to predict difficulty in mask ventilation. The aim of our study was to identify the methods for predicting difficult mask ventilation.
Methods: After ethical committee approval and informed consent, 120 adult patients undergoing general anaesthesia were studied. The following informations were obtained preoperatively: mouth opening, Mallampati oropharyngeal view class, jaw protrusion, extension of head and neck, thyromental distance and sternomental distance. After induction with propofol and vecuronium, the lungs were inflated using a ventilator (Servo 900c, pressure control mode with 15 cmH2O I:E=1:3, f=10) through a face mask. Mean tidal volumes were measured in the following positions: 1) neutral position of head and neck, 2) head tilt, 3) jaw thrust, 4) 2)+3), 5) 4) + oral airway insertion. Mask ventilation was arbitrary defined as easy when clinically sufficient tidal volumes (10 ml kg<) were obtained in 1)-3); difficult in 4) or 5). Fisher's exact test was used to compare the proportion of difficult mask ventilation. A P value of <0.05 was considered statistically significant.
Results and discussion: Mallampati Class 3, limitations of jaw protrusion and extension of head and neck were significant factors for predicting difficulty in mask ventilation (Table). Both sensitivity and specificity were highest in patients with Mallampati Class 3 (Table).
Conclusion: Difficult mask ventilation is predictable with preoperative physical examinations: Mallampati oropharyngeal view, jaw protrusion and extension of head and neck.
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