Haemodynamic changes during positive-pressure ventilation in children

Background: Positive-pressure ventilation may alter cardiac function. Our objective was to determine with the use of impedance cardiography (ICG) whether altering airway pressure modifies the central haemodynamics in mechanically ventilated children with no pulmonary pathology. Central venous saturation (ScvO2) was measured as an indicator of tissue perfusion. Methods: Twelve children between 7 and 65 months of age, requiring mechanical ventilation as a consequence of a non-pulmonary disease, were enrolled in the study. All patients had a central venous line as a part of their routine management. Using pressure controlled ventilation (PCV) the baseline PEEP value of 5 cmH(2)O (P-b5) was increased to 10 cmH(2)O (P-i10) and then to 15 cmH(2)O (P-i15). After P-i15, PEEP was decreased to 10 (P-d10) and then to 5 cmH(2)O (P-d5). Each time period lasted 5 min heart rate (HR), mean arterial blood pressure (MABP), central venous pressure (CVP), end-tidal carbon dioxide (ETCO2), mean airway pressure (P-aw), stroke volume index (SVI), cardiac index (CI) and central venous oxygen saturation (ScvO2) were recorded at the end of the five periods. Results: The values of CI did not change when 10 and 15 cmH(2)O of PEEP were applied. Elevation of PEEP and thus P-aw caused slight but not significant reductions in SVI and ScvO2 as compared to the baseline (T-b5). After reducing PEEP in T-d5 we found statistically significant elevations of SVI and CI, as compared to T-i15 heart rate, ETCO2 and MABP remained unchanged. Conclusion: We did not find significant haemodynamic changes following PEEP elevation in ventilated children, as measured using impedance cardiography. Reducing the value of PEEP to 5 cmH(2)O resulted in statistically significant SVI elevations. The values of ScvO2 remained unaffected.