Noninvasive monitoring of oxygenation during one-lung ventilation: a comparison of transcutaneous oxygen tension measurement and pulse oximetry.

Oxygenation was monitored concomitantly by measurement of transcutaneous oxygen tension and by pulse oximetry, and the data were compared with arterial blood oxygen tension and saturation values in 10 patients who became hypoxemic when undergoing thoracotomy and one-lung ventilation. A steep decrease in arterial blood oxygen tension was obvious immediately after the institution of one-lung ventilation, reaching the lowest mean value of 63 +/- 2 mm Hg (+/- SEM) at 12 minutes. Despite significant correlation between transcutaneous oxygen tension and arterial blood oxygen tension during one-lung ventilation (r = 0.75; P less than 0.001), the delay in the transcutaneous oxygen tension response resulted in underestimation of the severity of hypoxemia at the beginning of one-lung ventilation. In contrast, the decrease in arterial blood oxygen saturation from 97.9 +/- 0.3% to 92.2 +/- 0.8% as measured by CO-Oximeter was accurately followed by pulse oximetry with almost beat-to-beat response, bringing about a highly significant linear correlation between the two methods (r = 0.93; P less than 0.001). We conclude that pulse oximetry is a simpler and more rapidly responding method than measurement of transcutaneous oxygen tension for detection of hypoxemia during one-lung ventilation in adults.