RESUMO
STUDY OBJECTIVE: To assess the effects of desaturation on stroke index (SI), cardiac index (CI), and heart rate (HR) using the ICON continuous noninvasive cardiac output monitor in children undergoing general anesthesia. DESIGN: Retrospective analysis of a prospectively collected data set. SETTING: Pediatric operating rooms in a tertiary academic medical center. PATIENTS: Children younger than 20 years who experienced desaturation while undergoing general anesthesia. INTERVENTION: All records were retrospectively searched for desaturation events defined as a recorded Spo2 ≤ 90%. We compared the data from the prior 4 minutes (baseline) with mild, moderate, and severe levels of desaturation. MEASUREMENTS: The relationship between Spo2 and percent change in SI, CI, and HR from baseline was assessed using a generalized linear model with repeated measures and the least-squares method. MAIN RESULTS: Data from 446 patients were reviewed; 38 events were eligible for analysis after exclusions. There were significant decreases in SI at all saturation ranges below 95%: -6.5% (P < .001) for 85%-95%, -8.9% (P = .002) for 71%-84%, and -11% (P < .001) for ≤70%. Based on the result from the regression, Spo2 was associated with change in SI with borderline significance (P = .053) but not that of HR and CI. There was a strong relationship to desaturation events with young age (P < .001), particularly infants younger than 6 months. CONCLUSION: Events associated with desaturation in children under general anesthesia were significantly associated with decreased SI with a greater effect with lower saturation nadirs. It is unclear if other concurrent events could have also contributed to adverse hemodynamic responses during desaturation. In most children, a compensatory increase in HR generally offsets concurrent decreases in CI. It would appear that bradycardia is a late manifestation of hypoxemia.
