[Influence of salbutamol inhalation during volume target pressure control ventilation on ventilation parameters in patients with respiratory failure].

Objective: To compare the effects of volume target pressure control ventilation (VTPC) and volume control ventilation (VCV) on respiratory mechanics in patients with respiratory failure, and to investigate the effects of ventilated parameters after salbutamol inhalation.

Methods: Ten patients with mean age (68+/-5) years were intubated and mechanically ventilated for acute respiratory failure of diverse causes. After 30 minutes with VCV [tidal volume (VT) 8-10 ml/kg], measurements of respiratory mechanics were begun, and then the patients were ventilated with VTPC for 30 minutes. VCV and VTPC were repeated after salbutamol 600 microg inhalation.

Results: The static compliance (Cst) was (38.4+/-2.7) ml/cm H2O (1 cm H2O=0.098 kPa) and airway resistance (Raw) was (20.1+/-2.0) cm H2O x L(-1) x s(-1) in 10 patients. With the same tidal volume, peak inspiratory pressure (PIP) and mean inspiratory flow [VT/inflation time (Tinflate)]during VTPC were lower, but peak inspiratory flow (PIF) was significantly higher than that during VCV (all P<0.05). The same plateau pressure (Pplat) was observed during VCV as during VTPC, they were (22.1+/-0.9) cm H2O vs. (23.0+/-1.2) cm H2O. After salbutamol inhalation, PIP and Raw were significantly decreased in all patients (both P<0.05), but no changes were found in Cst and Pplat. PIF and peak expiratory flow (PEF) were increased much more during two modes than before inhalation (both P<0.05), but Tinflate was decreased (P<0.05).

Conclusion: VTPC is a new mechanical ventilation mode in which closed-loop control theory is used. The airway pressure during VTPC is associated with Cst and not influenced by Raw.