70 
CARDIAC MODELS 
Dibenzylene (1-2mg/Kg)- (8Dogs) 
6M 
5 
4 H 
3 
2 
1 -I 
0 
J::;: BASELINE 
^ SHOCK 
^ DIBENZYLENE 
* N.S. 
IT 
PR 
LVEDP 
(dynes/sec/cm j (mmHg) 
LVSW 
(g-m) 
LV dP/dt 
(mmHg/sec) 
Figure 9. — Same as in Figure 8. PR = peripheral re- 
sistence; LVEDP = left ventricular end-diastolic 
pressure; LVSW = left ventricular stroke work; LV 
dP/dt = left ventricular dP/dt. 
age cardiac output increased, it did not change 
in two animals and decreased in two. Heart rate 
also increased and the calculated stroke work 
decreased as did left ventricle dP/dt. Left ven- 
tricular end-diastolic pressure also decrease i. 
Three of the dogs developed frank pulmonarj- 
edema within one-half hour after therapy and 
died. Four of the dogs died within the next 12 
hours, only one dog lived beyond 48 hours, giv- 
ing a 24-hour mortality of 88%. 
In Group B, three subgroups were studied to 
test the effect of different dose levels of norepi- 
nephrine. Figures 10 and 11 show the response 
in eight dogs with the largest dose used, namely 
6-8 /igms/min norepinephrine administration. 
This amount of norepinephrine slightly in- 
creased mean blood pressure and stroke volume 
but decreased cardiac output and peripheral re- 
sistence. Left ventricular stroke work, left 
ventricular end-diastolic pressure and left ven- 
tricular dP/dt max slightly increased. The same 
changes were present in different degrees 
when the animals were treated with smaller 
doses of norepinephrine. In the first group with 
2-4 /xg/min of norepinephrine, peripheral re- 
sistence actually decreased and cardiac output 
slightly increased. The 24-hour mortality in 
these animals was 50% with five out of eight 
Norepinephrine (6-8|jgm/min ) — Duration 6-8hrs 
(BDogs) 
Baseline 
■■ SHOCK 
a» NOREPINEPHRINE 
200- 
ISO- 
160- 
140- 
120 
HR MBP 
(beats/min) (mmHg) 
CO sv 
(L/min) (ml/beat 
Figure 10. — Same as in Figure 8 for norepinephrine. 
surviving more than 24 hours in the group of 
the highest dose of norepinephrine. 
In Group C, phenoxybenzamine and volume 
expansion was combined with norepinephrine. 
Again, a significant decrease in mean blood 
pressure and periphera" resistence occurred de- 
spite of the norepinephrine addition. The sig- 
nificant fall in left ventricular end-diastolic 
pressure was also present. Despite this, three 
dogs developed pulmonary edema. The 24-hour 
mortality was 75% in this group. 
In Group D, isoproterenol alone and in combi- 
nation with norepinephrine was tested foUow- 
Norepinephrine (6-8pgm/min) — Duration 6-8hrs 
( 8 Dogs) 
baseline 
B SMOCK 
^ NOREPINEPHRINE 
6k- 
5 . 
4 ■ 
3 ■ 
2 
1 H 
0 
20- 
PR 
LVEDP 
(dynes/sec/cm'^) (mmHg) 
LVSW 
(g-m) 
LVdP/dt 
(mmHg/se 
Figure 11. — Same as in Figure 9 for norepinephrine. 
