Effect of mechanical ventilation on pulse oximetry variability in the postoperative period of cardiac surgery

Objective: To describe whether mechanical ventilation participates in the variability of pulse oximetry in subjects in critical conditions.Methods: Postoperative cardiac surgery subjects with and without mechanical ventilation were analyzed; their demographic variables, heart rate and arterial blood gases were defined.Variability was obtained from the comparison of arterial saturation (SaO 2 ) and partial oxygen saturation (SpO 2 ).They were obtained from blood gases, a pocket-sized Nonin pulse oximeter, and a Phillips monitor.It was analyzed with the Bland-Altman procedure.results: 260 subjects and 780 pairs comparisons were studied.The mean difference (bias) with and without mechanical ventilation: SaO 2 monitor 0.0 (6.3, -6.3) vs. 0.1 (6.3, -6.2); SaO 2 Nonin 1.2 (7.7, -5.3) vs. 1.4 (7.2, -4.4); SpO 2 Nonin -SpO 2 monitor 1.2 (6.6, -4.2) vs. 1.3 (5.8, -3.2).The heart rate: auscultation monitor -0.5 (3.6, -4.5) vs. -0.1 (3, -3.3); auscultation Nonin -1.1 (7.4,-9.7) vs. -0.8(4.2, -5.7); monitor -Nonin -0.6 (3, -4.3) vs. -0.6 (3, -4.3).conclusions: Mechanical ventilation does not increase heart rate or partial oxygen saturation variability in critically ill subject's post-cardiac surgery.