Mask Ventilation during Induction of General Anesthesia

Abstract

Background Depending on upper airway patency during anesthesia induction, tidal volume achieved by mask ventilation may vary. In 80 adult patients undergoing general anesthesia, the authors tested a hypothesis that tidal volume during mask ventilation is smaller in patients with sleep-disordered breathing priorly defined as apnea hypopnea index greater than 5 per hour. Methods One-hand mask ventilation with a constant ventilator setting (pressure-controlled ventilation) was started 20 s after injection of rocuronium and maintained for 1 min during anesthesia induction. Mask ventilation efficiency was assessed by the breath number needed to initially exceed 5 ml/kg ideal body weight of expiratory tidal volume (primary outcome) and tidal volumes (secondary outcomes) during initial 15 breaths (UMIN000012494). Results Tidal volume progressively increased by more than 70% in 1 min and did not differ between sleep-disordered breathing (n = 42) and non–sleep-disordered breathing (n = 38) patients. In post hoc subgroup analyses, the primary outcome breath number (mean [95% CI], 5.7 [4.1 to 7.3] vs. 1.7 [0.2 to 3.2] breath; P = 0.001) and mean tidal volume (6.5 [4.6 to 8.3] vs. 9.6 [7.7 to 11.4] ml/kg ideal body weight; P = 0.032) were significantly smaller in 20 sleep-disordered breathing patients with higher apnea hypopnea index (median [25th to 75th percentile]: 21.7 [17.6 to 31] per hour) than in 20 non–sleep disordered breathing subjects with lower apnea hypopnea index (1.0 [0.3 to 1.5] per hour). Obesity and occurrence of expiratory flow limitation during one-hand mask ventilation independently explained the reduction of efficiency of mask ventilation, while the use of two hands effectively normalized inefficient mask ventilation during one-hand mask ventilation. Conclusions One-hand mask ventilation is difficult in patients with obesity and severe sleep-disordered breathing particularly when expiratory flow limitation occurs during mask ventilation.

Palatal prolapse as a signature of expiratory flow limitation and inspiratory palatal collapse in patients with obstructive sleep apnoea

“…They reported expiratory obstruction during mouth-to-nose ventilation in obese anesthetized patients and hypothesized it to be caused by this valve-like behavior. More recently, Sato et al(16) also described the valve-like obstruction of the soft palate as a potential mechanism for the expiratory obstruction during mask ventilation in anesthetized patients with sleep disordered breathing(16). Our results add to this data by demonstrating, via direct observation of the soft palate and uvula, that the palate can indeed exhibit valve-like behavior on expiration.…”

“…In addition, research shows that expiratory flow limitation (EFL), which is coupled with inspiratory flow limitation in 50% of the breaths(11), is a common clinical finding(11–14) and could potentially be used to predict obstructive pulmonary disease(15) and the efficiency of mask ventilation during anesthesia induction(16) in patients with sleep disordered breathing. However, the mechanism of action remains unknown.…”

Dynamic behaviour of the soft palate during nasal positive pressure ventilation under anaesthesia and paralysis: comparison between patients with and without obstructive sleep-disordered breathing

“…In fact, in our recent study, the occurrence of expiratory flow limitation was found to be an independent risk factor for a reduction in the efficiency of mask ventilation. 3 Buffington and colleagues 5 also reported that expiratory airway obstruction, determined by clinical signs such as chest rise without falling and lack of a capnography waveform, occurred more frequently in anaesthetized persons with a narrower RP airway, and the presence of SDB was its independent risk factor. These findings are in agreement with Safar's milestone work, in which half of anaesthetized persons, particularly obese subjects, partially obstructed during nasal PPV.…”

“…1,2 Our recent study reports that tidal volume during one-hand mask ventilation in patients with severe SDB was significantly lower than in non-SDB subjects. 3 Despite the clinical significance of difficult mask ventilation in patients with SDB, no study has systematically explored its mechanisms in SDB patients, nor has the dynamic behaviour of the pharyngeal airway during positive pressure ventilation (PPV) been described in these patients.…”

Perioperative management of the obese surgical patient

“…27 [44][45][46] Among the risk factors for the development of OSA, obesity has the most influence especially in those <50 years and this is bidirectional (Fig. 1).…”