![]() ![]() ![]() Several indices have been described that either predict deadspace or track ventilatory efficiency at the bedside. Recently though there has been a resurgence of interest in ventilatory efficiency. Deadspace and with it ventilatory efficiency has been largely forgotten. Yet indices of oxygenation seem to be the mainstay when instigating or fine-tuning ventilatory strategies. Since its first description by Bohr in the late 19th century to the current use of single-breath test for volumetric CO 2, our understanding of the physiological deadspace has vastly improved. ![]() Measuring deadspace ventilation should be the most reliable method of monitoring ventilatory efficiency in mechanically ventilated patients. Supported by the Children's Hospital Foundation and equipment by Ohmeda, Inc.Problems with ventilatory efficiency results in abnormal CO 2 clearance. In this population, iNO reduced Qs/Qt, but redistribution of pulmonary blood flow does little to reduce Vd/Vt in patients with high airway pressure. Vd/Vt was significantly related to mean airway pressure(R=0.53, p<0.001). However, the mean paired difference in Vd/Vt after treatment with iNO compared to baseline was-0.03±.09 (N=133, p<0.001), and the distribution of Va/Q shifted towards lower values. Mean Vd/Vt was not significantly reduced by iNO (0.41±.21 vs. Treatment with iNO significantly reduced Qs/Qt (0.41±.16 vs. Data from 147 trials in 47 patients were analyzed. Virtual shunt (Qs/Qt) was calculated from SaO2 and the ideal alveolar pCO2 was calculated from PaCO2 and Qs/Qt, allowing the Pet-PaCO2 gradient to be partitioned into components from Qs/Qt and alveolar deadspace (Vd/Vt). Oxyhemoglobin saturation, inspired NO concentration, inspired and exhaled O2, N2, and CO2, and arterial gas tensions were monitored. ![]() We tested the hypothesis that iNO 2-50 ppm would redistribute pulmonary blood flow (Qs) with less dispersion of Qs and alveolar ventilation (Va) in infants and children with pulmonary hypertension due to PPHN or CHD. ![]()
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