Negative Pressure Ventilation vs External High-Frequency Oscillation During Rigid Bronchoscopy

Study objectives To compare the effectiveness of two modalities of external ventilation during rigid bronchoscopy: intermittent negative pressure ventilation (INPV) and external high-frequency oscillation (EHFO). Design Prospective, controlled, randomized, nonblinded study. Setting University-affiliated hospital. Patients Seventy patients undergoing interventional rigid bronchoscopy for tracheobronchial lesions were enrolled into the study. Interventions Mechanical ventilation was performed by INPV or EHFO. When pulse oximetry was Measurements and results Arterial blood gases were sampled preoperatively and intraoperatively. Most patients in both groups had normal intraoperative Pa co 2 (mean, 43.6 ± 11.8 mm Hg under EHFO and 37.4 ± 8.2 mm Hg under INPV; p = 0.012), and acidemia occurred in 9 of 35 patients of EHFO group and in 2 of 35 patients of INPV group (p = 0.049). Hypercapnia (Pa co 2 > 50 mm Hg) was observed in 10 patients under EHFO and in 2 with INPV (p = 0.026). Intraoperative mean Pa o 2 was similar (101.4 ± 52.9 mm Hg with EHFO and 124.2 ± 50.3 mm Hg with INPV; p = 0.07), but O 2 supply was different (3.5 ± 2.3 L/min during INPV and 8.5 ± 6.2 L/min during EHFO; p o 2 Conclusions External negative pressure ventilation appears to be a suitable choice during rigid bronchoscopy: both EHFO and INPV ensure effective ventilation and comfortable operating conditions in the majority of patients. Some patients may receive inadequate ventilation with EHFO, developing respiratory acidosis and requiring manually assisted ventilation. In comparison with INPV, EHFO requires a higher fraction of inspired oxygen.