The Science Journal of the American Association for Respiratory Care

2005 OPEN FORUM Abstracts

Comparison of Ventilator Stay and Mortality between Closed-Loop/Non-closed Loop Mechanical Ventilation

Ronald R. Sanderson, RRT, DrPH; Denise Wheatley, RRT; Kimi Soca, RN, Christopher Batacan, BS, MCP - Castle Medical Center, Kailua, Hawaii

Question: Can microprocessor based, closed-loop ventilation be used safely and effectively as the exclusive method of mechanical ventilation?

Method: 196 patients were managed exclusively on closed-loop ventilation Adaptive Support Ventilation (ASV) - Hamilton Medical - Galileo Ventilator while 684 patients received mechanical ventilation using usual, non-closed-loop technology. Ventilator management of both groups was accomplished in the same ICU, with the same staff, same standard of care and managed by the same mix of primary care physicians. This is a report of a series of patients receiving clinical care in a small hospital of 157 beds. No experimental methods were used and no study parameters were defined prior to or during data collection. Data was collected in a customized Access database application constructed to collect data to assess mechanical ventilation outcomes in a small medical center ICU. Data was collected similarly on all patients and analyzed retrospectively. This is a convenience sample and excluded all ventilator patients who spent time on both closed-loop technology and non-closed loop technology.

Results: ASV Only No ASV
Number of patients 196 684
Average hours on ventilator 81.7 94.1
95% CI - hours on ventilator 81.7 +/- 35.2 94.1 +/- 35.1
Range of days on ventilator 0.003 - 57.3 0.01 - 68.5
% Mortality on ventilator 8.7 17.1

The patients in both groups had a similar range of time on mechanical ventilation as well as average time on the ventilator. Ventilator patient mortality on closed-loop ventilation was 1/2 that of non-closed loop ventilation.

These results are subject to bias from multiple sources because of the convenience sample. There may have been practitioner bias in favor or opposed to closed-loop ventilation. There was no clear difference in patient acuity between the two groups, but acuity was not measured.

Conclusion: Because of the similar hours on the ventilator and mortality data, closed-loop ventilation appears to be a safe ventilator strategy. Further study of decreased mortality and length of stay associated with closed-loop ventilation may be warranted.

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