Intra-aortic Balloon Counterpulsation: Potential for Therapy in Hemorrhagic Shock with Associated Myocardial Failure H. J. PROCTOR, M.D., F.A.C.S.,° H. HSIAO, PH.D., JAMES FRY, B.A.,
CHARLES EBERT, M.D.
From the Department of Surgery, After attaching appropriate monitoring devices enabling the University of North Carolina School of Medicine, measurement of the slope of the left ventricular function curve, Chapel Hill, North Carolina 27514 left atrial pressure, mean aortic pressure, peak left ventricular pressure, and tension time index, three groups of ten dogs were subjected to varying periods of hemorrhagic shock until a slope of their ventricular function curve was reduced to either 75% tion of the severity of the failure. In this investigation, three (Group I), 50% (Group II), or 25% (Group III) of their baseline different degrees of myocardial failure were created in value. Resuscitation was attempted in all dogs by the intra- animals to determine the quantitative improvement in myovenous infusion of shed blood plus additional balanced salt solu- cardial ftunction associated with IABC and to relate that imtion. This infusate was administered to maintain either the mean aortic pressure within 15 mm Hg of the baseline value or a left provement to improved survival. atrial pressure of 15 mm Hg, whichever occurred first. One half Methods of the dogs received, in addition, intra-aortic balloon counterpulsation. All dogs not receiving counterpulsation expired within two hours. There was no apparent effect of counter- Preparation of Animals pulsation on Group I animals. Three of five animals (Group II) Mongrel dogs in excess of 20 kg were utilized. After and four of five animals (Group III) receiving counterpulsation anesthetization with pentabarbital sodium, all animals were survived to the end of the experiment with significant (p < .01) improvement in the parameters monitored. The utilization of intubated and connected to a Harvard respirator. A median counterpulsation as an adjunct to treatment in hemorrhagic sternotomy with attachment of an electromagnetic flow shock is suggested. probe,' pressure monitoring cannulas, and insertion of a
counterpuilsation balloont in the descending thoracic aorta counterpulsation were then performed as illustrated in Fig. 1. This prepahas been an increasingly attractive approach to support- ration enabled the continuous monitoring of right atrial ing an injured and failing myocardium. Specifically, intra- pressure (RAP), left arterial pressure (LAP), left ventricular aortic balloon counterpuilsation (IABC) is an effective pressure (LVP), peak left ventricular pressure (PLVP), method of compensating for myocardial failure following mean aortic pressure (MAP), cardiac output (CO) and the myocardial infarction.'8'14 This investigation was under- calculation of peripheral vascular resistance (PVR). Tension taken to evaluate the potential role of IABC as a therapeutic time index (TTI) was approximated by integrating the area modality in myocardial failure following hemorrhagic beneath the left ventricular pressure curve. A pump-oxyshock. 1,2,7,10 genator circuit as illustrated in Fig. 1 facilitated the infusion It seemed necessary to determine if the potential degree of oxygenated blood into the left atrium and enabled the of support offered by IABC to the failing heart was a func- construction of the slope of the left ventricular function curve by plotting change in left atrial pressure against I N HECENT YEARS the principle of
Stubmitted for publication May 20, 1974. Suipported in part by NIH Grant 1-0-160-4264-VB098, and by the North Carolina Heart Association Grant 1-0-107-4264-ME061 ° Jefferson-Pilot Research Fellow.
Carolina Medical Electronics. Model IV Counterpulser,
f Westinghouse 120
Avco Balloon.
Vol. 181 * No. I
INTRA-AORTIC BALLOON COUNTERPULSATION
Fic. 1. Diagramatic illustration of the experimental preparation.
change in cardiac output. (Moseley Autograph, Model 2050 AM X-Y Recorder). Experimental Design Three groups of ten dogs were studied. After preparation of the animals and collection of baseline data as described above, an oxygenated mixture of whole blood and balanced salt solution was infused into the left atrium for ten seconds at a flow rate of 10 ml/sec, and the slope of the resulting baseline left ventricular function curve was noted. All animals were bled through their arterial cannula until the MAP was reduced to 40 mm Hg. The measurements described above were successively repeated at 30-minute intervals. MAP was maintained at 40 mm Hg by intermittent infusion or withdrawal of blood until a specific degree of left ventrictular failure was achieved as measured by a reduction in the slope of the left ventricular function curve when compared with the baseline slope. The three groups were reduced respectively to: Group I, 75%; Group II, 50%; and Group III, 25%. After the desired degree of myocardial failure was achieved in each group, a mixture of shed blood plus balanced salt solution was infused intravenously until either the MAP returned to within 15 mm Hg of the baseline value
121 or until the mean LAP reached 15 mm Hg. If left atrial pressure reached 15 mm Hg before mean aortic pressure was within 15 mm Hg of the baseline value, the infusion was discontinued until left atrial pressure had decreased to 10 mm Hg, at which point infusion resumed. The measurements described above were then repeated. After these measurements, each group of ten dogs was alternately divided into two sub-groups of five. One sub-group received only intermittent volume restoration in an attempt to maintain mean aortic pressure within 15 mm Hg of baseline, while the other sub-grouip received continuous IABC in addition to intermittent volume infusion. Measurements were continued at 30-minute intervals in all animals for four hours or until the death of the animal.
Results The Quantitative Effect of IABC The effect of IABC on those parameters describing left ventricular performance is depicted in Table 1. These data were collected immediately after initial volume restoration and compares animals with and without IABC. Utilizing a paired t test, it was shown that in the group with the most myocardial failure (Group I), IABC had no statistically significant effect (p > .01) in terms of the parameters monitored. One animal in Group I expired during the shock period. In both Groups II and III a significant (p < .01) improvement was noted for all parameters with the exception of TTI in Group II and TTI and PLVP in Group III. PLVP was significantly (p < .01) increased in Group II. Comparison of the data collected from Groups II and III does not seem to indicate any significant quantitative difference in the magnitude of the response to IABC for these groups. The Effect of IABC on Survival Group I. It required from three to five hours of MAP = 40 mm Hg to achieve a 75% reduction in the slope of the ventricular function curve. It is evident from Table 1 that neither the infusion of intravenous fluid alone nor infusion of fluid in conjunction with IABC was capable of fully restoring any parameter to its baseline value. As might be expected from this lack of response to IABC on the part of Group I animals, there was no prolongation of life noted in conjunction with IABC, death occurring in all animals in both sub-grouips by 90 minutes after the end of the shock period. Group II. It required 21/2-4 hours of MAP = 40 mm Hg. to achieve a 50% reduction in left ventricular function. As noted in Table 1, IABC had a significant effect upon left ventricular performance. This effect appears to be sustained for two to three hours and was associated with improved survival (Fig. 2). All but one animal not receiving IABC support expired
PROCTOR AND OTHERS
122
TABLE 1. Response to IABCfor Three Degrees of Myocardial Failure
(roup I (75%( slope) x
NlAIA
LAP1
s.eC.
.x s.C 0l
(C0
X s.C.
PLV'P
S.C.
TTI
s.e.
.x
Baseline
3 IABC
c IABC
1)05 3.63 4 .O55 2.83 4 .3.25 .93 4 142.8 .9.65 4 96.6 8.25 4
21.6 8.18 4 16.3 2.53 4 .44 .19 4 41.3 6.28 4 62.5 4.33 4
20.2 6.33 4 15.8 2.86 4 .38 .22 4 40.1 5.35 4 68.6 8.69 4
p >.01
>.01 >.01
>.01
>.01
(Groip 11 (50% slope) Baseline X
MAP
s.eC. II x
LAP
s.eC. 0l
(CO
seC. 0l x
PIAVP
s.eC
0l x
'r[i
s.eC.
.986 4.46
.a 6.69 1.92 5 2.21 .57 .5 13.3.6 8.17 .5 83 7.89 5
IABC 28.7 5.37 5 14.9 1.85 5 .63 .16 5 52.8 6.82 5 34.8 5.37 5
c IABC
50.6 4.75 5 8.7 1.02 5 1.41 .39 5 78.2 3.51 5 49.5 6.89 5
Grotip III (25% ) slope) Baseline s IABC c IABC x
101.5 5.13 5
MAP
s.e(1 0l
IAP
S.C.
1.35
Ii
J5
7.8 2.06 .46 5 146.2 9.25
38.3 4.28 5 10.3 1.2 5 .86 .13 5 59.3 7.15 5 30.8 4.80 5
65.5 5.01 5 8.7 .99 5 1.95 .41 5 68.2 2.88 5 35.2 7.25 5
p
CHARLES EBERT, M.D.
From the Department of Surgery, After attaching appropriate monitoring devices enabling the University of North Carolina School of Medicine, measurement of the slope of the left ventricular function curve, Chapel Hill, North Carolina 27514 left atrial pressure, mean aortic pressure, peak left ventricular pressure, and tension time index, three groups of ten dogs were subjected to varying periods of hemorrhagic shock until a slope of their ventricular function curve was reduced to either 75% tion of the severity of the failure. In this investigation, three (Group I), 50% (Group II), or 25% (Group III) of their baseline different degrees of myocardial failure were created in value. Resuscitation was attempted in all dogs by the intra- animals to determine the quantitative improvement in myovenous infusion of shed blood plus additional balanced salt solu- cardial ftunction associated with IABC and to relate that imtion. This infusate was administered to maintain either the mean aortic pressure within 15 mm Hg of the baseline value or a left provement to improved survival. atrial pressure of 15 mm Hg, whichever occurred first. One half Methods of the dogs received, in addition, intra-aortic balloon counterpulsation. All dogs not receiving counterpulsation expired within two hours. There was no apparent effect of counter- Preparation of Animals pulsation on Group I animals. Three of five animals (Group II) Mongrel dogs in excess of 20 kg were utilized. After and four of five animals (Group III) receiving counterpulsation anesthetization with pentabarbital sodium, all animals were survived to the end of the experiment with significant (p < .01) improvement in the parameters monitored. The utilization of intubated and connected to a Harvard respirator. A median counterpulsation as an adjunct to treatment in hemorrhagic sternotomy with attachment of an electromagnetic flow shock is suggested. probe,' pressure monitoring cannulas, and insertion of a
counterpuilsation balloont in the descending thoracic aorta counterpulsation were then performed as illustrated in Fig. 1. This prepahas been an increasingly attractive approach to support- ration enabled the continuous monitoring of right atrial ing an injured and failing myocardium. Specifically, intra- pressure (RAP), left arterial pressure (LAP), left ventricular aortic balloon counterpuilsation (IABC) is an effective pressure (LVP), peak left ventricular pressure (PLVP), method of compensating for myocardial failure following mean aortic pressure (MAP), cardiac output (CO) and the myocardial infarction.'8'14 This investigation was under- calculation of peripheral vascular resistance (PVR). Tension taken to evaluate the potential role of IABC as a therapeutic time index (TTI) was approximated by integrating the area modality in myocardial failure following hemorrhagic beneath the left ventricular pressure curve. A pump-oxyshock. 1,2,7,10 genator circuit as illustrated in Fig. 1 facilitated the infusion It seemed necessary to determine if the potential degree of oxygenated blood into the left atrium and enabled the of support offered by IABC to the failing heart was a func- construction of the slope of the left ventricular function curve by plotting change in left atrial pressure against I N HECENT YEARS the principle of
Stubmitted for publication May 20, 1974. Suipported in part by NIH Grant 1-0-160-4264-VB098, and by the North Carolina Heart Association Grant 1-0-107-4264-ME061 ° Jefferson-Pilot Research Fellow.
Carolina Medical Electronics. Model IV Counterpulser,
f Westinghouse 120
Avco Balloon.
Vol. 181 * No. I
INTRA-AORTIC BALLOON COUNTERPULSATION
Fic. 1. Diagramatic illustration of the experimental preparation.
change in cardiac output. (Moseley Autograph, Model 2050 AM X-Y Recorder). Experimental Design Three groups of ten dogs were studied. After preparation of the animals and collection of baseline data as described above, an oxygenated mixture of whole blood and balanced salt solution was infused into the left atrium for ten seconds at a flow rate of 10 ml/sec, and the slope of the resulting baseline left ventricular function curve was noted. All animals were bled through their arterial cannula until the MAP was reduced to 40 mm Hg. The measurements described above were successively repeated at 30-minute intervals. MAP was maintained at 40 mm Hg by intermittent infusion or withdrawal of blood until a specific degree of left ventrictular failure was achieved as measured by a reduction in the slope of the left ventricular function curve when compared with the baseline slope. The three groups were reduced respectively to: Group I, 75%; Group II, 50%; and Group III, 25%. After the desired degree of myocardial failure was achieved in each group, a mixture of shed blood plus balanced salt solution was infused intravenously until either the MAP returned to within 15 mm Hg of the baseline value
121 or until the mean LAP reached 15 mm Hg. If left atrial pressure reached 15 mm Hg before mean aortic pressure was within 15 mm Hg of the baseline value, the infusion was discontinued until left atrial pressure had decreased to 10 mm Hg, at which point infusion resumed. The measurements described above were then repeated. After these measurements, each group of ten dogs was alternately divided into two sub-groups of five. One sub-group received only intermittent volume restoration in an attempt to maintain mean aortic pressure within 15 mm Hg of baseline, while the other sub-grouip received continuous IABC in addition to intermittent volume infusion. Measurements were continued at 30-minute intervals in all animals for four hours or until the death of the animal.
Results The Quantitative Effect of IABC The effect of IABC on those parameters describing left ventricular performance is depicted in Table 1. These data were collected immediately after initial volume restoration and compares animals with and without IABC. Utilizing a paired t test, it was shown that in the group with the most myocardial failure (Group I), IABC had no statistically significant effect (p > .01) in terms of the parameters monitored. One animal in Group I expired during the shock period. In both Groups II and III a significant (p < .01) improvement was noted for all parameters with the exception of TTI in Group II and TTI and PLVP in Group III. PLVP was significantly (p < .01) increased in Group II. Comparison of the data collected from Groups II and III does not seem to indicate any significant quantitative difference in the magnitude of the response to IABC for these groups. The Effect of IABC on Survival Group I. It required from three to five hours of MAP = 40 mm Hg to achieve a 75% reduction in the slope of the ventricular function curve. It is evident from Table 1 that neither the infusion of intravenous fluid alone nor infusion of fluid in conjunction with IABC was capable of fully restoring any parameter to its baseline value. As might be expected from this lack of response to IABC on the part of Group I animals, there was no prolongation of life noted in conjunction with IABC, death occurring in all animals in both sub-grouips by 90 minutes after the end of the shock period. Group II. It required 21/2-4 hours of MAP = 40 mm Hg. to achieve a 50% reduction in left ventricular function. As noted in Table 1, IABC had a significant effect upon left ventricular performance. This effect appears to be sustained for two to three hours and was associated with improved survival (Fig. 2). All but one animal not receiving IABC support expired
PROCTOR AND OTHERS
122
TABLE 1. Response to IABCfor Three Degrees of Myocardial Failure
(roup I (75%( slope) x
NlAIA
LAP1
s.eC.
.x s.C 0l
(C0
X s.C.
PLV'P
S.C.
TTI
s.e.
.x
Baseline
3 IABC
c IABC
1)05 3.63 4 .O55 2.83 4 .3.25 .93 4 142.8 .9.65 4 96.6 8.25 4
21.6 8.18 4 16.3 2.53 4 .44 .19 4 41.3 6.28 4 62.5 4.33 4
20.2 6.33 4 15.8 2.86 4 .38 .22 4 40.1 5.35 4 68.6 8.69 4
p >.01
>.01 >.01
>.01
>.01
(Groip 11 (50% slope) Baseline X
MAP
s.eC. II x
LAP
s.eC. 0l
(CO
seC. 0l x
PIAVP
s.eC
0l x
'r[i
s.eC.
.986 4.46
.a 6.69 1.92 5 2.21 .57 .5 13.3.6 8.17 .5 83 7.89 5
IABC 28.7 5.37 5 14.9 1.85 5 .63 .16 5 52.8 6.82 5 34.8 5.37 5
c IABC
50.6 4.75 5 8.7 1.02 5 1.41 .39 5 78.2 3.51 5 49.5 6.89 5
Grotip III (25% ) slope) Baseline s IABC c IABC x
101.5 5.13 5
MAP
s.e(1 0l
IAP
S.C.
1.35
Ii
J5
7.8 2.06 .46 5 146.2 9.25
38.3 4.28 5 10.3 1.2 5 .86 .13 5 59.3 7.15 5 30.8 4.80 5
65.5 5.01 5 8.7 .99 5 1.95 .41 5 68.2 2.88 5 35.2 7.25 5
p
