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.

Figure 2 Representative polysomnograph of periodic obstructive apnea that occurred during endoscopic submucosal dissection under propofol sedation. Thoraco-abdominal respiratory movements showed obstructive disturbance represented by paradoxical movements. Despite these long apneas lasting more than one minute, SaO₂ levels remained > 95%.

Figure 3 Typical polysomnograph of an obstructive hypopnea that occurred during endoscopic submucosal dissection under propofol sedation. Obstructive hypopnea episodes were diagnosed based on paradoxical thoraco-abdominal wall movements and flattened nasal pressure waves and resolved spontaneously with gradual increase in airflow caused by an increase in breathing effort.

Figure 4 Frequency of respiratory disturbances detected by pulse oximetry and polysomnography. All patients experienced respiratory disturbances during propofol sedation (total AHI: 10.44 ± 5.68/h). Total apnea hypopnea index (AHI) was significantly greater with polysomnography than with pulse oximetry (1.54 ± 1.81/h, P < 0.001). Obstructive AHI (9.26 ± 5.44/h) was significantly greater than central AHI (1.19 ± 0.90/h, P < 0.001).