Background: In an effort to prevent and address perioperative hypoxemia, it has become customary to provide supplemental oxygen to all surgical patients. Recently, the value of such a practice has been questioned. This study was designed to determine the incidence as well as the potential risk factors associated with perioperative hypoxemia. Methods: During a 9 - week period, 84 ASA I-II patients who underwent ambulatory surgical procedures under spinal anesthesia were observed. Arterial oxygen saturation (SpO2) was monitored using a pulse oximeter prior to induction of anesthesia, during operation and until the patient was discharged from the recovery room. Patients breathed room air during the entire perioperative course unless dyspnea and/or desaturation occurred. Descriptive statistics was used to examine differences in oxygen saturations before, during, and after surgery. The association between each of the potential risk factors and the number of patients requiring supplemental oxygen was analyzed using Fisher's exact test (for attribute data e.g. level of sensory block) and the Wilcoxon's rank sum test for continuous data (e.g. age, smoking in pack years) to calculate the probability that the proportions did not differ. A/>< 0.05 was considered statistically significant. Results: The incidence of preoperative, intra-operative and postoperative hypoxemia was 0 percent, 0 percent and 1.14 percent respectively while the need for supplemental oxygen was 2.27 percent intra-operatively and 2.27 percent postoperatively. Statistical analysis revealed that the level of block and body mass index were significant factors (P < 0.05) influencing the need for oxygen support. The need for supplemental oxygen was not associated with age, smoking history, surgical position, sedation level and Visual Analog Scale score. Conclusion: Results suggest that seemingly healthy patients who undergo lower abdominal, urologic, gynecologic or lower extremity surgical procedures under spinal anesthesia are at a low risk for hypoxemia. Pulse oximetry as part of routine monitoring may obviate the need for supplemental oxygen in this patient population. (Author)
Human ; ANESTHESIA ; ANOXEMIA ; OXIMETRY ; ANESTHESIA, SPINAL ; AMBULATORY SURGICAL PROCEDURES

Ten critically-ill preterm infants with severe hyaline membrane disease received tolazoline because of persistent hypoxemia refractory to the administration of 100% oxygen and mechanical ventilation. Seven infants (70%) responded immediately with an increase in PaO2 greater than or equal to 20 mmHg in the umbilical arterial gas within 60 minutes after bolus infusion (1 to 2 mg/kg) of tolazoline. Twenty-four hours later after the tolazoline infusion, the FiO2 had been decreased from 1.0 to a mean of 0.82 +/- 0.16, and the MAP from 16.5 +/- 1.8 to 15.6 +/- 4.5 cm H2O. Four of 7 infants (57%) who had an immediate response survived, whereas none survived out of 3 infants who failed to respond initially. Three infants experienced relatively severe complications possibly related to tolazoline. There appears to be a place for the use of tolazoline in a severely hypoxemic infant with hyaline membrane disease who is being ventilated, and in whom arterial oxygenation cannot be improved by a further increase in the inspired oxygen concentration or by an alteration of ventilator settings.
Anoxemia/*drug therapy ; Human ; Hyaline Membrane Disease/*complications ; Infant ; Infant, Newborn ; Infusions, Intravenous ; Support, Non-U.S. Gov't ; Tolazoline/administration & dosage/*therapeutic use