Abstract
Objective: To assess the effects of the association of positive end-expiratory pressure (PEEP) with different inflation volumes (VT's) on passive lung deflation and alveolar recruitment in ARDS patients.¶Design: Clinical study using PEEP with two different VT's and analyzing whether passive lung deflation and alveolar recruitment (Vrec) depend on end-inspired (EILV) or end-expired (EELV) lung volume in mechanically ventilated ARDS patients.¶Setting: Medical intensive care unit in a university hospital.¶Patients and participants: Six mechanically ventilated consecutive supine patients with ARDS.¶Interventions: Time-course of thoracic volume decay during passive expiration and Vrec were investigated in six ARDS patients ventilated on PEEP with baseline VT (VT,b) and 0.5VT (0.5VT,b), and on zero PEEP (ZEEP) with VT,b. Time constants of the fast (τ 1) and slow (τ 2) emptying compartments, as well as resistances and elastances were also determined.¶Measurements and results: (a) the bi-exponential model best fitted the volume decay in all instances. The fast compartment was responsible for 84 ± 7 (0.5VT,b) and 86 ± 5 % (VT,b) on PEEP vs 81 ± 6 % (VT,b) on ZEEP (P:ns) of the exhaled VT, with τ 1 of 0.50 ± 0.13 and 0.58 ± 0.17 s vs 0.35 ± 0.11 s, respectively; (b) only τ 1 for VT,b on PEEP differed significantly (P < 0.02) from the one on ZEEP, suggesting a slower initial emptying; (c) for the same PEEP, Vrec was higher with a higher volume (VT,b) than at a lesser one (0.5VT,b), reflecting the higher VT.¶Conclusions: In mechanically ventilated ARDS patients: (a) the behavior of airway resistance seems to depend on the degree of the prevailing lung distension; (b) alveolar recruitment appears to be more important when higher tidal volumes are used during mechanical ventilation on PEEP; (c) PEEP changes the mechanical properties of the respiratory system fast-emptying compartment.
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Received: 16 June 1999 Final revision received: 31 March 2000 Accepted: 7 April 2000
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Chelucci, GL., Dall'Ava-Santucci, J., Dhainaut, JF. et al. Association of PEEP with two different inflation volumes in ARDS patients: effects on passive lung deflation and alveolar recruitment. Intensive Care Med 26, 870–877 (2000). https://doi.org/10.1007/s001340051275
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DOI: https://doi.org/10.1007/s001340051275