The Science Journal of the American Association for Respiratory Care

1996 OPEN FORUM Abstracts

DETERMINING THE PRESENCE AND INCIDENCE OF INTRINSIC-PEEP (P_{1}) USING TWO DIFFERENT TECHNIQUES.

James J Lawson RRT, Kettering Medical Center, Dayton, Ohio 45429

Introduction: The incidence of PEEP_{1} has been previously reported to be between 10 and 46% in mechanically ventilated (MV) ICU patients. PEEP_{1} may cause hypoxemia, hypercarbia, increased work of breathing, and hemodynamic compromised in MV patients. This study was designed to assess the incidence of PEEP_{1} using two techniques: 1) assessing the expiratory flow waveform; and 2) measuring airway pressure during an expiratory hold. Method: During the two month study period beginning January 1996, each MV patient in SICU and MICU was evaluated for the presence of PEEP_{1} using each technique. All patients were ventilated with a Nellcor/Puritan-Bennet 7200ae, Siemens 300, or Siemens 900C ventilator. Expiratory flow waveform was evaluated using the 7200ae graphics package or with a bedside monitor (Navigator, Newport Medical) for any patient on a Siemens ventilator. PEEP_{1} was determined to be present if the expiratory flow did not return to zero prior to the onset of the next inspiration. Expiratory hold was provided by use of each ventilator's expiratory hold feature. An expiratory hold of 2 seconds was attempted with each measurement. PEEP_{1} was determined to be present if, in the absence of patient effort, pressure in the breathing circuit was above set PEEP at the end of the 2 second expiratory hold. Measurements were made BID, three days per week during the study period. Results: Thirty patients were monitored and a total of 150 PEEP_{1} assessments were made. Eleven (36.6%) patients had PEEP_{1} according to the expiratory flow waveform assessment on 80 occasions. Only four (13.3%) of those patients had measurable PEEP_{1} using the expiratory port occlusion technique on 30 occasions. Eight of the eleven (73%)patients with PEEP_{1} were admitted to the MICU with a primary respiratory diagnosis. Discussion: Incidence of PEEP_{1} in our pt population is similar to that reported by others. The majority of expiratory port occlusion maneuvers were aborted due to presence of patient effort. Use of airway pressure and flow graphics has increased our awareness of PEEP_{1} and patient-ventilator interaction during MV in the ICU. Limitations to the use of flow waveform assessment to confirm PEEP_{1} are that PEEP_{1} may not be quantitated using this technique and PEEP_{1} may be present while expiratory flow is zero due to dynamic airways collapse. Conclusion: The overall incidence of PEEP_{1} is highest when using expiratory flow waveform monitoring. Further work is needed to correlate the expiratory flow waveform to the quantitatively measured PEEP_{1}.

Reference: OF-96-163

You are here: RCJournal.com » Past OPEN FORUM Abstracts » 1996 Abstracts » DETERMINING THE PRESENCE AND INCIDENCE OF INTRINSIC-PEEP (P_{1}) USING TWO DIFFERENT TECHNIQUES.