To the Editor:
Gift et al.  state that the rational cost-effective use of supplemental oxygen in the early postoperative period in patients that have undergone peripheral surgery can be adjusted according to the level of oxygen saturation upon admission to the postanesthesia care unit (PACU). From this point of view, a safe level of oxygen saturation might indicate that routine oxygen administration is unnecessary . Gift et al. propose a level of 92% oxygen saturation on arrival to the PACU as safe. However, their patients were receiving oxygen supplementation during transfer from the operating room to the PACU and probably high oxygen concentrations were given at the end of anesthesia. I believe that this is the reason why they measured higher levels of oxygen saturation on admission to the PACU (97%) in comparison to other studies [3-5]. In our study , cited by them, we considered oxygen saturation on admission to be the level measured 10 min after arrival while the patients were breathing air room; in addition, our patients did not receive oxygen supplementation during the transfer. Our mean value under these conditions was 90.7%, and for the subset of patients that had undergone peripheral surgery it was 92%. I think that the conclusion drawn by the authors that oxygen can be reserved only for patients with oxygen saturation below 92% at the time of admission to the PACU should be taken very cautiously. In the first minutes after anesthesia, there is considerable danger of deep hypoxemia appearing due to factors such as age, preexisting disease, persistent mismatch of ventilation to perfusion, and residual effects of drugs given during general anesthesia or sedation for regional anesthesia . Even when discontinuing supplemental oxygen 30 min after arrival to the PACU, a high incidence of hypoxemic episodes not related to type of surgery has been observed . For all these reasons, I continue to believe that even when patients have undergone peripheral surgery all of them should receive oxygen supplementation systematically during the early postoperative period. For the same reason it is now accepted that all patients must receive oxygen during transfer from the operating room to the PACU . All studies have demonstrated that oxygen, no matter how it is administered, easily relieves postoperative hypoxemia .
Jaume Canet, MD
Department of Anesthesiology, Hospital Universitari Germans Trias i Pujol, Badalona, 08916 Barcelona, Spain
1. Gift AG, Stanik J, Karpenick J, et al. Oxygen saturation in postoperative patients at low risk for hypoxemia: is oxygen therapy needed? Anesth Analg 1995;80:368-72.
2. DiBenedetto RJ, Graves SA, Gravenstein N, Konicek C. Pulse oximetry can change routine oxygen supplementation practices in the postanesthesia care unit. Anesth Analg 1994;78:365-8.
3. Tyler IL, Tantisira B, Winter PM, Motoyama EK. Continuous monitoring of arterial oxygen saturation with pulse oximetry during transfer to the recovery room. Anesth Analg 1985;64:1108-12.
4. Canet J, Ricos M, Vidal F. Early postoperative arterial oxygen desaturation. Determining factors and response to oxygen therapy. Anesth Analg 1989;69:207-12.
5. Moller JT, Wittrup M, Johansen SH. Hypoxemia in the postanesthesia care unit: an observer study. Anesthesiology 1990;73:890-5.
6. Craig DB. Postoperative recovery of pulmonary function. Anesth Analg 1981;60:46-51.
7. Daley MD, Norman PH, Colmenares ME, Sandler AN. Hypoxaemia in adults in the post-anaesthesia care unit. Can J Anaesth 1991;38:740-6.
8. Hudes ET, Marans HJ, Hirano GM, et al. Recovery room oxygenation: a comparison of nasal catheters and 40 percent oxygen masks. Can J Anaesth 1989;36:20-4.