The Science Journal of the American Association for Respiratory Care

2007 OPEN FORUM Abstracts

DOSES OF ISOFLURANE TO DECREASE PEAK INSPIRATORY PRESSURES IN PATIENTS WITH LIFE-THREATENING BRONCHOSPASM: A RETROSPECTIVE CHART REVIEW

C. Duclos1, D. C. Heitz1, D. A. Turner1


Introduction:
Isoflurane (ISO) is an anesthetic agent with bronchodilating properties. It is used on patients with potentially life-threatening bronchospasm when other treatments are unsuccessful. This retrospective chart study looked at the dose of isoflurane needed to decrease peak inspiratory pressures (PIP) to less than 30 cmH20 in patients from 1994-2006. The primary hypothesis is higher doses of isoflurane result in a decrease in peak inspiratory pressures.

Methods: 32 patients were included in this study. Data collected included demographics, when the patient was intubated, placed on isoflurane, when isoflurane was discontinued, and when the patient was extubated. Ventilator data was collected while on isoflurane at various time intervals. Also looked at was how long it took to decrease PIPs to less than 30 cmH2O after initiation of isoflurane.

Results: Based on the data collected, the average dose of isoflurane that dropped the patients’ PIP to less than 30 cmH2O was 0.7%. The average maximum dose given to a patient was 1.1%. There were 17 patients whose PIPs did not rise above 30 cm H2O. The remaining 15 patients took an average of 9 hours after the initiation of isoflurane for the peak pressure to drop to below 30 cmH2O. Of interest is that there were 11 patients whose PIP decreased to less than 30 cmH2O, but the dose was progressively increased. The maximum dose was 0.5% or greater than the dose needed to decrease the peak pressure to less than 30 cmH2O. This entire subset of patients was placed on pressors due to periods of hypotension.

Conclusions:
Based on the data, higher doses of isoflurane resulted in a decrease in peak inspiratory pressures. However, the outcomes may be different with a larger sample size. Although higher doses did reflect a decrease in PIPs, it also caused an increased incidence of side effects including hypotension. The therapeutic dose of isoflurane needed to decrease peak inspiratory pressures to less than 30 cmH2O needs to be monitored so that benefits are maximized and side effects minimized.

   Standard Deviation
Maximum Dose (avg.) 1.10% n=32 0.57
ISO Dose (avg.) 0.72% n=32 0.44
Time Until PIP < 30 9 hrs. n=15 4.76
Side Effects 27 n=32  
Maximum Dose < 0.5 11 patients   



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