Background. To compare the effects of nitric oxide (NO) inhalation, positive end-expiratory pressure (PEEP) and both strategies, on gas exchange and hemodynamics in patients with severe acute respiratory failure. Methods. We studied six patients with severe acute respiratory failure (five with acute respiratory distress syndrome and one with acute lung injury). A thoracic-pulmonary pressure-volume curve was performed in all patients to determine the inflexion point. Patients were ventilated with four different patterns, always with FiO2=1: 1. Without NO inhalation or PEEP (baseline). 2. With NO inhalation. 3. With PEEP (equal to the inflection point or to 10 cm H2O if there was no inflection point). 4. With PEEP and NO inhalation. The last 3 patterns were applied in random order. Gas exchange and hemodynamic parameters were measured after 30 minutes for stabilization while being ventilated with each pattern. Results. Basal PaO2/FiO2was 102 ± 70 mmHg. With NO inhalation, PaO2/FiO2was 137 ± 76 mmHg; with PEEP, 121 ± 62 mmHg, and with PEEP and NO inhalation, 200 ± 73 mmHg (p < 0.001). The PaO2/FiO2increase as compared to baseline was 32.3 ± 31.2% with PEEP, 46.7 ± 69.3% with NO inhalation, and 138.5 ± 129.5% with PEEP and NO inhalation (p < 0.05). Baseline shunt was 43 ± 13%, 40 ± 15% with NO, 33 ± 6% with PEEP, and 25 ± 6% with PEEP and NO inhalation (p < 0.001). There were no changes in PaCO2, mean pulmonary artery pressure, mean artery pressure, and systemic and pulmonary vascular resistance indexes. Conclusion. PEEP and NO inhalation have synergistic effects on gas exchange in patients with severe acute respiratory failure.
|Publication status||Published - 1 Jun 1996|
- Acute respiratory distress syndrome (ARDS)
- Acute respiratory failure
- Nitric oxide (NO)