The Science Journal of the American Association for Respiratory Care

2002 OPEN FORUM Abstracts

THE EFFECTS OF CLOSED-LOOP, AUTOFEEDBACK WEANING APPROACHES ON THERAPIST/VENTILATOR INTERACTION IN THE IMMEDIATE POST-OP PATIENT.

Mark Rose RRT, Mike Trevino RRT, Anne Francis RRT, Gail Whitford RRT, Gary L. Weinstein MD, FCCP. Presbyterian Hospital of Dallas

 INTRODUCTION: It has been conceptualized that ?the immediate post-operative patient might be ideally suited for simple automatic feedback modes that provide a backup form of support? (Respir Care 2002;47(1):69-90). This study compared and contrasted the viability of utilizing an autofeedback, closed-loop weaning approach to immediate post-op patients, with an emphasis on how that might impact therapist interactions with the ventilator. The population was limited to 18 post-operative open-heart patients during one month of 2002. We compared a weaning approach that utilized the Seimens Servo 300a ventilator and its available Automode/PRVC (Pressure Regulated Volume Control) with a standard SIMV/PS weaning approach.

METHODOLOGY: The control population was weaned with the SIMV/PS approach using the following weaning procedure. When the patient demonstrated capability of spontaneous respirations, the RR was decreased by 2 breaths at a time as quickly as tolerated, ultimately placing the patient on CPAP/PS. It should be noted that PS of 8-12cwp was utilized to overcome resistance in the airway. The PRVC/Automode group was weaned as described. Upon noting spontaneous respirations, the ?set Vt? was decreased to 5ml/kg/IBW and ?set RR? at 75-125% of spontaneous RR. Both groups had an initial ABG drawn to correlate ETCO2 and SaO2 monitoring. During the weaning phase, the HR, RR, Spont. Vt, ETCO2 and SaO2 were monitored to determine continued tolerance. An ABG was drawn for both groups following approximately 30 minutes of totally spontaneous respiration. Extubation criteria for both groups included: RSBI < 105, FVC > 10ml/kg/IBW, MIP > -20cwp.

Results: In the PRVC/Automode population there was a 64% reduction in therapist/ventilator interactions. As indicated in the following tables, a 24% reduction in total time on the ventilator was also appreciated for the PRVC/Automode group.

Patients in PRVC/Automode group 10
Average time on ventilator 4.125 hours
Shortest time on ventilator 1.75 hours
Longest time on ventilator 6 hours
Average # of therapist/ventilator interactions 1.4
Patients in SIMV/PS group 8
Average time on ventilator 5.4 hours
Shortest time on ventilator 3 hours
Longest time on ventilator 9.5 hours
Average # of therapist/ventilator interactions 3.9

CONCLUSION: We found the PRVC/Automode approach to weaning to be an alternative that is both efficient and safe. This approach appears to provide the therapist, that is dedicated to a busy ICU, with a tool that permits rapid, safe, and effective post-op weaning coupled with the flexibility to perform other useful tasks in the ICU. It should be noted that the re-intubation rate for this study was zero. A larger, expanded study is warranted to better quantify the usefulness of this approach.

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