High-frequency oscillatory ventilation compared with conventional mechanical ventilation associated with inhaled nitric oxide: a randomized crossover study in children with acute hypoxemic respiratory failure

PURPOSE: To compare the acute oxygenation effects of high-frequency oscillatory ventilation (HFOV) plus inhaled nitric oxide (iNO) with conventional mechanical ventilation (CMV) plus iNO in acute hypoxemic respiratory failure (AHRF) children. METHODS: Children with AHRF, aged between 1 month and 14 years under CMV with PEEP ≥ 10 cmH2O were randomly assigned to CMV (CMVG, n = 14) or HFOV (HFVG, n = 14) in a crossover design. Oxygenation indexes and hemodynamic variables were recorded at enrollment (Tind), 1 hr after CMV start (T0) and then every 4 hr (T4h, etc.). RESULTS: PaO2/FiO2 significantly increased after 4 hr compared to enrollment in both groups [(CMVG -Tind: 111.95 ± 37 < T4h: 143.88 ± 47.5 mmHg, p < 0.05; HFVG-Tind: 123.76 ± 33 < T4h:194.61± 62.42 mmHg, p < 0.05)] without statistical differences between groups. At T8h, PaO2/FiO2 was greater for HFVG compared with CMVG (HFVG: 227.9 ± 80.7 > CMVG: 171.21 ± 52.9 mmHg, p < 0.05). FiO2 could be significantly reduced after 4 hr for HFVG (HFVG-T4h: 0.53 ± 0.09 < Tind: 0.64 ± 0.2; P < 0.05) but only after 8 hr for CMVG. Comparing groups at T8h, it was observed that FiO2 decrease was greater for HFVG (HFVG: 0.47 ± 0.06 < CMVG: 0.58 ± 0.1; p < 0.05). CONCLUSION: Both ventilatory techniques with iNO improve oxygenation. HFOV causes earlier FiO2 reduction and increased PaO2/FiO2 ratio compared to CMV at 8 hr. However, at the end of the protocol, there was no significant difference and no clinical improvement derived from the application of both ventilatory strategies with iNO. It is not possible to say what would have happened if a different conventional ventilatory mode had been used, given the fact that our study has a limited number of patients included in each group.