Polysomnographic assessment of respiratory disturbance during deep propofol sedation for endoscopic submucosal dissection of gastric tumors

Figure 1 Representative polysomnographic recording of a long central apnea episode occurring soon after a bolus injection of propofol (2 mg/kg) and pentazocine (7. 5 mg), followed by continuous infusion of propofol (2 mg/kg per hour) in a 67-year-old female. Chin-lift airway maneuver (shown by an arrowhead) restored breathing once; however, central apnea redeveloped, resulting in severe hypoxemia (SaO₂, 67%); the hypoxemia reversed gradually with improvement in breathing efforts. Polysomnography could detect apnea 40 s before the observed decrease in SaO₂ levels.