Ineffectiveness of arterial pressure measurement and cardiac rate in detecting hypoxemia in the postanesthetic period

: The purpose of the study was to analyze the hemodynamic response to hypoxemia induced during the first postoperative hour. We studied 151 patients who underwent general anesthesia for elective surgery. Arterial saturation of oxyhemoglobin (SpO2), heart rate (HR), and systolic arterial pressure (SAP) during respiration with atmospheric air were measured 20 min and 80 min after admission at the recovery room. We compared HR and SAP between hypoxemic (SpO2 less than or equal to 90%) and non-hypoxemic patients (SpO2 greater than 90%) and we did not find significant differences. SpO2 failed to correlate with HR or with SAP in any of the time samples. This lack of correlation was also observed between patients with or without halogenated anesthetic treatment. Our results indicate that the possible inhibitory effect of anesthesia on hemodynamic response to hypoxemia lasts at least during the first postoperative hour and it does not depend on the administration of halogenated anesthetics. We also conclude that postoperative hemodynamic stability is not an accurate index of the status of arterial oxygenation.