Background: Changes in Paco2 have not been described during thoracoscopy under sedation-assisted local anesthesia. We hypothesized that hypoventilation might occur secondary to administration of sedatives and decreased ventilation in one lung.
Aim: Prospectively measure cutaneous carbon dioxide tension (Pcco2) in addition to pulse oximetric saturation (Spo2) using a new combined digital sensor to examine the occurrence of hypoventilation during thoracoscopy under sedation-assisted local anesthesia.
Setting: University hospital.
Methods: Following validation studies, Pcco2 was prospectively measured in 16 consecutive patients undergoing thoracoscopy under sedation-assisted local anesthesia using a combined digital earlobe sensor measuring Spo2 (percentage) and Pcco2 (millimeters of mercury). All patients received supplemental oxygen. Routine BP monitoring and Spo2 was continued. Patients received IV hydrocodone, 5 mg, and intermittent boluses or IV midazolam and pethidine.
Results: Mean baseline Pcco2 measurement was 39.1 ± 7.2 mm Hg (± SD) [range, 27.5 to 50.5 mm Hg], and peak measurement during the procedure was 52.3 ± 10.3 mm Hg (range, 37.2 to 77 mm Hg) [p < 0.001]. Median and mean changes in Pcco2 measurement from baseline were 13.0 mm Hg and 13.2 ± 5.3 mm Hg (range, 5.5 to 27.8 mm Hg), respectively. Mean fall in Spo2 during the procedure was 4.6 ± 3.2% (range, 1 to 14%).
Conclusions: Thoracoscopy performed under sedation-assisted local anesthesia is associated with significant hypoventilation. Combined measurement of Spo2 and Pcco2 during thoracoscopy is a novel approach in the monitoring of ventilation, enhancing patient safety, and might allow to guide the administration of sedation in a better way.