STATIC INTRINSIC PEEP IN COPD PATIENTS DURING SPONTANEOUS BREATHING

Intrinsic positive end-expiratory pressure (PEEPi) is routinely determ ined under static conditions by occluding the airway at end-expiration (PEEPi,st). This procedure may be difficult in patients with chronic obstructive pulmonary disease (COPD) during spontaneous breathing, as both expiratory muscle activity and increased respiratory frequency of ten occur. To overcome these problems, we tested the hypothesis that t he difference between maximum airway opening (MIP) and maximum esophag eal (Ppl max) pressures, obtained with a Mueller maneuver from the end -expiratory lung volume (EELV), can accurately measure PEEPi,st. Using this method, we found that, in eight ventilator-dependent tracheostom ized COPD patients (age 71 +/- 7 yr), PEEPi,st averaged 13.0 +/- 2.9 c m H2O. That measurement was validated by comparison with a reference s tatic PEEPi (PEEPi,st-Ref) taken at the same EELV adopted by patients during spontaneous breathing, and measured on the passive quasi-static pressure-volume (P/V) curve of the respiratory system, obtained durin g mechanical ventilation. PEEPi,st-Ref averaged 13.1 +/- 3.0 cm H2O, i .e., a value essentially equal to PEEPi,st measured by means of our te chnique. We conclude that PEEPi,st can be accurately assessed in spont aneous breathing COPD patients by the difference between MIP and Ppl m ax during the Mueller maneuver.