The Science Journal of the American Association for Respiratory Care

1998 OPEN FORUM Abstracts

INTEGRATION OF MANDATORY MINUTE VOLUME VENTILATION INTO AN EXISTING POST CARDIOTHORACIC SURGERY WEANING PROTOCOL

Don Renaghan RRT, Respiratory Care Services Stanford University Medical Center Stanford, California

Purpose Our ongoing study (N=40 to date) integrates the mode of Mandatory Minute Volume ventilation (MMV), as delivered by the Drager Evita ventilator, into our existing postoperative cardiothoracic surgery weaning protocol. By design, the MMV mode will allow a complete transition to unassisted spontaneous breathing once the patient initiates and maintains a predetermined V_{E}. Upon completion of the study, data from a non-MMV group (N=62) will be compared to identify differences in: hours intubated, days in ICU, and number of parameter changes between MMV and non-MMV patients within the same weaning protocol.

Methods Randomly selected post operative cardiothoracic surgery patients, who meet the clinical criteria in the existing rapid weaning protocol, are placed on the Drager Evita ventilator in the MMV mode. The only weaning protocol modification, in conjunction with the inclusion of MMV, eliminates the need for incremental rate decreases during the "weaning phase" of the protocol. Continuous patient/ventilator data is collected through a dedicated Digital HiNote laptop computer utilizing Evita View monitoring software. CareVue (Hewlett-Packard) information systems provide complete clinical profiles during the post-operative period.

Results Early comparative data reveals a decrease in hours intubated in the MMV group, although not statistically significant. MMV did allow for significantly fewer parameter adjustments, not including FiO_{2} changes, in the transition to spontaneous breathing. The time to onset of complete spontaneous breathing in the MMV group averaged 6.8 ± 4.8 hours, compared to the average duration of parameter adjusted weaning (non-MMV) to spontaneous breathing of 10.2 ± 4.7 hours.

Comparative Data

Non-MMV (N=62) MMV (N=40 to date)

(Mean ± SD)

Hrs. Intubated 11.9 ± 5.3 10.8 ± 5.0

Time to Spont.

Breathing (Hrs.) 10.2 ± 4.7 6.8 ± 4.8

No. of Vent.

Parameter [DELTA]'s 5 ± 4 1 ± 1

Conclusions MMV, as delivered by the Drager Evita ventilator, can enhance a rapid weaning protocol by allowing the patient's drive to breathe to be the determining factor in a transition to unassisted spontaneous breathing with few, or no, incremental adjustments in set rate or mode. The inclusion of MMV in a weaning protocol can provide an opportunity for earlier extubation and a potentially shorter duration of mechanical ventilation for stable post-operative cardiothoracic surgery patients.

The 44th International Respiratory Congress Abstracts-On-Disk®, November 7 - 10, 1998, Atlanta, Georgia.

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