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Comparison of five bilevel pressure ventilators in patients with chronic ventilatory failure: a physiologic study
Vitacca M, Barbano L, d'Anna S, Porta R, Bianchi L, Ambrosino N
Chest 2002 Dec;122(6):2105-2114
clinical trial
5/10 [Eligibility criteria: Yes; Random allocation: Yes; Concealed allocation: No; Baseline comparability: No; Blind subjects: Yes; Blind therapists: No; Blind assessors: No; Adequate follow-up: Yes; Intention-to-treat analysis: No; Between-group comparisons: Yes; Point estimates and variability: Yes. Note: Eligibility criteria item does not contribute to total score] *This score has been confirmed*

OBJECTIVE: To compare patient-ventilator interaction and comfort in patients with chronic ventilatory failure (CVF) who are undergoing noninvasive positive-pressure ventilation with five different commercial bilevel pressure home ventilators. Also, we wanted to evaluate the short-term effects of the five ventilators on physiologic variables, namely, breathing patterns and inspiratory muscles. DESIGN: Randomized, controlled physiologic study. SETTING: Pulmonary division of a rehabilitation institution. PATIENTS: Twenty-eight patients with CVF due to COPD (17 patients) and restrictive chest wall diseases (11 patients). MEASUREMENTS: Sensation of comfort, breathing patterns and minute ventilation (E), respiratory muscles and mechanics, and patient-ventilator interaction during both unassisted and assisted ventilation with the five ventilators applied randomly. RESULTS: The five ventilators showed different flow and pressure waveforms. The level of comfort was somehow different among the studied ventilators. When compared to unassisted ventilation, all ventilators induced a significant increase in E (p < 0.01) without any significant difference among ventilators. Use of the five ventilators resulted in significant differences in peak airway opening pressure (Pao-peak) but not in mean airway opening pressure computed over a period of 1 min (PTPao-min), and in a duty cycle. Ineffective efforts (IEs) were similar among the studied ventilators. In comparison with unassisted ventilation, all ventilators induced significant reductions in inspiratory muscle effort (p < 0.001). No significant relationship was found between level of comfort and PTPao-min, Pao-peak, or the number of IEs. CONCLUSIONS: In stable, awake patients with CVF, all of the studied ventilators were well-tolerated, although with a great intersubject variability in comfort, and performed well in terms of improvement in E and inspiratory muscle unloading, thus fulfilling the aims of mechanical ventilation. This effect was obtained with similar levels of PTPao-min, despite the fact that Pao-peak was different among some ventilators. The number of IEs was similar among the studied ventilators.

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