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).
Prospective, controlled, randomized, nonblinded study.
Setting: University-affiliated hospital.
Patients: Seventy patients undergoing interventional rigid
bronchoscopy for tracheobronchial lesions were enrolled into the
Interventions: Mechanical ventilation was
performed by INPV or EHFO. When pulse oximetry was < 90%, manually
assisted ventilation was delivered.
results: Arterial blood gases were sampled preoperatively and
intraoperatively. Most patients in both groups had normal
intraoperative Paco2 (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
(Paco2 > 50 mm Hg) was observed in 10
patients under EHFO and in 2 with INPV (p = 0.026). Intraoperative
mean Pao2 was similar (101.4 ± 52.9 mm Hg
with EHFO and 124.2 ± 50.3 mm Hg with INPV; p = 0.07), but
O2 supply was different (3.5 ± 2.3 L/min during INPV and
8.5 ± 6.2 L/min during EHFO; p < 0.001). Intraoperative hypoxemia
(Pao2 < 60 mm Hg) occurred in five patients
with EHFO and two with INPV (p = 0.426). Three EHFO patients required
manually assisted ventilation (mean, 0.2 ± 0.9), but no INPV patient
did (p = 0.142).
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