CLINICAL-EVALUATION OF DIMINISHED EARLY EXPIRATORY FLOW (DEEF) VENTILATION IN MECHANICALLY VENTILATED COPD PATIENTS

Objective: To evaluate the cardiopulmonary effects, especially the end -expiratory lung volume (EEV) and ventilation inhomogeneity during dim inished early expiratory flow ventilation (DEEF), which resembles purs ed-lips breathing, with the conventional intermittent positive pressur e ventilation (IPPV) in postoperative mechanically ventilated patients with chronic obstructive pulmonary disease (COPD). Design: A prospect ive study measuring cardiopulmonary parameters during IPPV, DEEP, and positive end-expiratory pressure (PEEP) as a control mode. In the PEEP mode, PEEP values were chosen such that the mean airway pressure duri ng a breath cycle was equal to that during the DEEF mode, which was hi gher than the conventional IPPV mode. Setting: Surgical intensive care unit of a university hospital. Patients: 20 postoperative mechanicall y ventilated COPD patients who were optimally pretreated and had norma l blood oxygenation. Interventions: Measurements were started in the I PPV (IPPV1) mode, continued in a randomized order with DEEF or PEEP, a nd completed with a second IPPV (IPPV2) mode, with Ih equilibration ti me in each mode before each measurement. Measurements and results. A m ulti-breath indicator gas wash-out test was used to calculate the EEV and ventilation inhomogeneity. There was a 9% increase (p < 0.05) in t he mean EEV during both the DEEF and PEEP mode compared to IPPV. No si gnificant changes in the ventilation inhomogeneity and deadspace fract ions or the hemodynamic parameters were found during the different ven tilatory modes. Conclusions: There was no improvement in pulmonary and hemodynamic parameters during the DEEP mode in comparison to the IPPV mode. The small increase in EEV during DEEP was probably caused by th e slightly higher mean expiratory pressures as in the PEEP mode. Howev er, this had no effect on the hemodynamic parameters. As we could not observe any improvement with the DEEP ventilation in our optimally pre treated postoperative COPD patients, we do not advise applying this th erapy in this group of patients, since this mode of ventilation may ca use barotrauma if not monitored adequately.