Anesthesia related hypoxemia. The effect of pulse oximetry monitoring on perioperative events and postoperative complications.

The objectives of the present investigation were to evaluate the extent of perioperative hypoxemia and to investigate the impact of pulse oximetry monitoring on the extent of hypoxemia and on perioperative morbidity in adults. To accomplish these objectives a number of prospective studies were carried out. The incidence, duration, and severity of hypoxemia were evaluated in two single blinded observer studies in the operating room (N = 296) (I) and in the Postanesthesia Care Unit (N = 200) (II). Pulse oximetry monitoring's effect on the extent of hypoxemia was evaluated in a randomized blinded observer study of 200 patients (III). The impact of pulse oximetry on the frequency of perioperative events, changes in patient care, and post-operative complications were studied in a randomized evaluation of 20,802 patients (IV-V). Finally, a subgroup of 736 patients already included in the randomized evaluation was psychologically evaluated pre- and postoperatively (VI). In the observer studies in the OR and PACU mild hypoxemia (SpO2 86-90%) was recorded in 53% and 55% of the patients, respectively. Severe hypoxemia with SpO2 values < 81% was recorded in 20% and 13% of the patients, respectively. In the randomized blinded observer study, patients with pulse oximeter data available had a significantly reduced incidence of perioperative hypoxemia when compared to patients where the data were unavailable. Most noteworthy was that in the available group extreme hypoxemia (SpO2 < 76%) was not encountered in the OR and both severe (SpO2 76-80%) and extreme hypoxemia were not observed in the PACU. In the randomized evaluation of pulse oximetry significantly more patients in the oximetry group experienced at least one respiratory event than did control patients in both the OR and in the PACU. This was a result of a 19 fold increase in the incidence of diagnosed hypoxemia in the oximetry group than in the control group. In the OR cardiovascular events were observed in a similar number of patients in both groups, except myocardial ischemia, which was detected in 12 patients in the oximetry group and in 26 patients in the control group (P < 0.03). Several changes in PACU care were observed in association with the use of pulse oximetry. These included higher flow rates of supplemental oxygen (P < 0.00001), increased use of supplemental oxygen at discharge (P < 0.00001), and increased use of naloxone (P < 0.02). One or more postoperative complications occurred in 10% of the patients in the oximetry group and in 9.4% in the control group (NS).(ABSTRACT TRUNCATED AT 400 WORDS)