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ISOFLURANE DOES NOT IMPROVE RETURN OF MYOCARDIAL FUNCTION AFTER GLOBAL ISCHEMIA IN DOGS

Haile, Michael MD; Heerdt, Paul MD, PhD; Kang, Richard BA; Blanck, Thomas J.J. MD, PhD

doi: 10.1097/00000539-199802001-00066
Abstracts of Posters Presented at the International Anesthesia Research Society; 72nd Clinical and Scientific Congress; Orlando, FL; March 7-11, 1998: Cardiovascular Anesthesia
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Anesthesiology Depts., Hospital for Special Surgery. (Heerdt, Kang) New York Hospital. Cornell University Medical Center. NY, NY.

Abstract S66

INTRODUCTION: Previous data indicate that isoflurane (ISO) exposure prior to regional ischemia and reperfusion improves return of regional function. The role of ISO in global ischemia and reperfusion in intact animals remains unclear. This study examined the effect of ISO pretreatment on recovery of LV function in dogs after a period of ventricular fibrillation (VF).

METHODS: After Animal Care Committee approval, dogs anesthetized with alpha-chloralose, morphine, and nitrous oxide were instrumented for simultaneous measurement of LV Pressure and Volume. Systolic LV function was quantified as the maximal rate of rise of LV pressure corrected for EDV(+dP/dt/EDV) and Ejection fraction (EF). Diastolic function was quantified by calculation of the time constant of isovolumic relaxation (tau) and a chamber stiffness constant (Kp). After thoracotomy and baseline measurements 4 dogs were treated with 1.5% ISO for one-half hour; 4 controls received no ISO during that period. A rapid pacing current was then applied to the LV inducing immediate VF. After 8 minutes of VF open chest cardiopulmonary resuscitation was initiated, with injection of epinephrine (20[micro sign]g/kg) and sodium bicarbonate (1 meq/kg). Internal defibrillation was then performed with return of spontaneous circulation in all dogs. Measurements obtained before and 1, 2, and 3 hours after VF were compared with ANOVA for repeated measures with P<or=to 0.05 regarded as significant.

RESULTS: The data below shows that in contrast to studies of regional ischemia and reperfusion, LV function was the same in both groups before VF and at all time points after VF. (Figure 1)

Figure 1

Figure 1

DISCUSSION: These data indicate that ISO pretreatment prior to global ischemia does not accelerate recovery of LV systolic or diastolic function in the first three hours after resuscitation. It remains to be determined whether ISO pretreatment yields demonstrable improvement in LV function at longer intervals. [1]

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REFERENCES

1. Anesthesiology, August 1997; Volume 87 Number 2:pp. 361-370.
© 1998 International Anesthesia Research Society