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On-line monitoring of intrinsic PEEP in ventilator-dependent patients

2000; American Physiological Society; Volume: 89; Issue: 3 Linguagem: Inglês

10.1152/jappl.2000.89.3.985

8750-7587

Gianluca Nucci, M Mergoni, C. Bricchi, Guido Polese, Claudio Cobelli, Andrea Rossi,

Neonatal Respiratory Health Research

Measurement of the intrinsic positive end-expiratory pressure (PEEP i ) is important in planning the management of ventilated patients. Here, a new recursive least squares method for on-line monitoring of PEEP i is proposed for mechanically ventilated patients. The procedure is based on the first-order model of respiratory mechanics applied to experimental measurements obtained from eight ventilator-dependent patients ventilated with four different ventilatory modes. The model PEEP i (PEEP i,mod ) was recursively constructed on an inspiration-by-inspiration basis. The results were compared with two well-established techniques to assess PEEP i : end-expiratory occlusion to measure static PEEP i (PEEP i,st ) and change in airway pressure preceding the onset of inspiratory airflow to measure dynamic PEEP i (PEEP i,dyn ). PEEP i,mod was significantly correlated with both PEEP i,dyn ( r = 0.77) and PEEP i,st ( r= 0.90). PEEP i,mod (5.6 ± 3.4 cmH 2 O) was systematically >PEEP i,dyn and PEEP i,st (2.7 ± 1.9 and 8.1 ± 5.5 cmH 2 O, respectively), in all the models without external PEEP. Focusing on the five patients with chronic obstructive pulmonary disease, PEEP i,mod was significantly correlated with PEEP i,st ( r = 0.71), whereas PEEP i,dyn ( r = 0.22) was not. When PEEP was set 5 cmH 2 O above PEEP i,st , all the methods correctly estimated total PEEP, i.e., 11.8 ± 5.3, 12.5 ± 5.0, and 12.0 ± 4.7 cmH 2 O for PEEP i,mod , PEEP i,st , and PEEP i,dyn , respectively, and were highly correlated (0.97–0.99). We interpreted PEEP i,mod as the lower bound of PEEP i,st and concluded that our method is suitable for on-line monitoring of PEEP i in mechanically ventilated patients.