An Analysis of Oxygen Consumption and Oxygen Delivery in Euthermic Infants After Cardiopulmonary Bypass With Modified Ultrafiltration
BACKGROUND: The balance between systemic oxygen consumption (O2) and delivery (DO2) is impaired after cardiopulmonary bypass (CPB) and is related to systemic inflammatory response syndrome. We sought to assess O2 and DO2 and their relationship with proinflammatory cytokines after CPB with the use of modified ultrafiltration (MUF) in infants.
METHODS: Sixteen infants, aged 1–11.5 months (median, 6.3 months), undergoing hypothermic CPB with MUF were studied during the first 12 hours after arrival in the intensive care unit (ICU). The central temperature was maintained at 36.8–37.1°C using external cooling or warming. O2 was continuously measured using respiratory mass spectrometry. Arterial blood samples for the tumor necrosis factor (TNF), interleukin-6 (IL-6), and interleukin-8 (IL-8) were taken and DO2 was calculated using the Fick principle on arrival at the ICU, and 2, 4, 8, and 12 hours postoperatively. Cytokines were additionally measured after induction of anesthesia and at the end of MUF.
RESULTS: O2 significantly decreased by 18.8% during the study period. DO2 was depressed throughout this period and reached a nadir at 8 hours (357.1 ± 136.2 ml · min–1 · m–2). The decrease in cytokines was accompanied with the decrease in O2 despite varied relationships between the levels of each of the cytokines and O2 measurements.
CONCLUSIONS: Our data indicate an unusual continuous decrease in O2 during the first 12 hours after CPB in infants. Control of body temperature to maintain euthermia in addition to the use of MUF may be beneficial to the balance between O2 and DO2 in the early postoperative period.
