[A study on hemodynamics in the brain death in dogs, with particular reference to left ventricular pressure-volume...

The hemodynamics of the brain death state still remains unknown in many respects. With special reference to the left ventricular pressure-volume relationship, hemodynamics was analyzed in 26 dogs which were subjected to complete cerebral destruction and catecholamine administration to prevent marked hypotension caused by brain death. The catecholamine used was dopamine (5-15 gamma; DA group), dobutamine (5-15 gamma; DOB group), noradrenaline (0.5-1.5 gamma; NAD group) and adrenaline (0.5-1.5 gamma, AD group). Left ventricular volume was calculated according to the approximate formula by Suga et al., using a pair of sonomicromanometers installed at the maximum internal transverse diameter. The indices determined were end systolic elastance (Ees), effective arterial elastance (Ea), ejection fraction (EF), mean Vcf, peak dP/dT and other hemodynamic parameters routinely used. The results were as follows: 1) the effect of catecholamine on Ees prior to brain death was DA = DOB greater than NAD = AD. 2) Peak dP/dT after brain death was significantly reduced to 56-73% of the pre-brain-death value. 3) Ees after brain death was significantly reduced to 56-73% of the pre-brain-death value (except for NAD 1.0 & 1.5 gamma: not significantly reduced), whereas Ea was significantly reduced to 43-70% (except for AD group: unchanged). As a result, Ea/Ees was reduced in both DA group (10 & 15 gamma) and NAD group (1.0 & 1.5 gamma) compared with their pre-brain-death values. 4) EF in DA and NAD groups was higher than the pre-brain-death value, showing a tendency dissociating from Ees. 5) EF was found to be mainly dependent on Ea/Ees according to the formula by Sunagawa et al. 6) AD was the only catecholamine which neither decreased peripheral vascular resistance nor changed Ea. It was concluded in the author's study using the above brain death model that 1) responses of catecholamine to the peripheral vascular system were of lesser grade than those to the heart, and 2) Ea/Ees (ventriculo-arterial coupling) should be extremely useful in evaluating left ventricular performance on the basis of the cardio-vascular hemodynamic relationship, and was strongly suggested to be a reliable index of left ventricular performance in brain death.