Arterial oxygen desaturation during only one of two similar thoracoscopic procedures on the same patient

The present report describes two similar thoracoscopic procedures performed on the same 81-year-old male patient. Because acute hypoxia had developed during one-lung ventilation on the first occasion, serial blood gases were taken during the second. Also, whereas on the first occasion the non-ventilated lung had been left open to air when one-lung ventilation was initiated, on the second it was connected to an ambient pressure oxygen source with the object of theoretically enabling apnoeic oxygenation during lung collapse. It is argued that this fundamental difference in anaesthetic practice may have contributed to the improved oxygenation that was recorded during the second thoracoscopy.