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Vasodepressive effects of the venous effluent following canine liver allotransplantation
VASODEPRESSIVE FOLLOWING WILLIAM
EFFECTS OF THE VENOUS EFFLUENT CANINE LIVER ALLOTRANSPLANTATION L.
AND
JOSEPH,
M.D.,
WILLIAM
ERIC P.
SYSTEMIC HYPOTENSION has been observed to follow revascularization of the transplanted canine liver. Although the etiology of this phenomenon remains unclear, it has been suggested that release of hepatic metabolites into the general circulation or that hypovolemia secondary to pooling of blood, either in the transplanted liver or the splanchnic circulation, may be the cause. Prophylactic administration of blood before and during revascularization does not obviate this complication [7, 9, 15, 171. The study reported here was designed to examine the venous effluent which pools in the transplanted liver immediately following revascularization, in order to quantitate metabolic changes and isolate “vasoactive” substances which might induce hypotension.
MATERIALS
AND
METHODS
The techniques of orthotopic and heterotopic liver transplantation have been described in previous reports [5, 61. After the From the Department of Surgery, UCLA School Medicine, Los Angeles, Calif. *lohn and Maw R. Markle Scholar in Academic Me&cine. ’ This work was supported in part by U.S. Public Health Service Training Grant GM 1559, and a Grant from the Califorgia Institute for Cancer Research. Submitted for publication July 27, 1967.
of
W.
LONGMIRE,
FONKALSRUD, JR.,
M.D.,* M.D.
donor liver was excised, a large plastic cannula was placed in the infrahepatic vena cava to be used for decompression upon revascularization of the transplanted liver (Fig. 1). After the vena cava and hepatic artery anastomoses were completed and after flow to the artery was restored, the venous effluent was allowed to drain by gravity through the cannula into sterile heparinized bottles. The vena caval anastomosis was occluded during the period in which the effluent was collected (from 10 to 15 min.). Thirty-five mongrel dogs, weighing from 14 to 21 kg., were used to assess the toxic effects of the venous effluent. They were fed regular kennel rations preoperatively and were immunized against hepatitis and distemper. Sterile technique was used throughout the experiment. The animals were anesthetized with intravenous sodium pentothal and intubated, and anesthesia was maintained with a light nitrous oxide-oxygen mixture. The left femoral vein was cannulated for infusion of the effluent. The left femoral artery was cannulated to record the blood pressure with a Statham strain-gauge transducer. The right jugular vein was cannulated for constant measurement of central venous pressure. Each dog was monitored for a period of from 10 to 20 minutes to allow equilibration of pressures. The dogs were divided into five groups, depending upon the amount and frac367
JOURNAL
OF
SURGICAL
RESEARCH
VOL.
8
NO.
8,
AUGUST
1968
again injected. In 7 dogs 100 cc. of the plasma fraction were injected; in the other 8 dogs, 50 cc. of the plasma fraction were infused.
RESULTS
Fig. 1. Technique of collecting hepatic effluent following partial revascularization allograft.
venous of liver
tion of the effluent and the type of operative procedure performed. Group 1: An exploratory laparotomy was performed on 5 dogs and 100 cc. of the hepatic venous effluent were injected. Group 2: A portacaval shunt was performed on 5 dogs. After stabilization of the arterial and venous pressures 100 cc. of the effluent were injected into each dog. Group 3: In another group of 5 dogs, a portacaval shunt was performed and followed by occlusion of the hepatic artery, the afferent loop of the portacaval shunt, and the hepatic veins. After the vital signs had been stabilized for approximately 15 minutes, 100 cc. of effluent were injected. Grou), 4: The procedure as described in Group 3 was again performed in 5 dogs with occlusion of blood supply to the liver. After stabilization 100 cc. of the erythrocyte fraction of the effluent were infused into each dog. Group 5: In 15 dogs the above procedures were performed again, and after occlusion of the blood supply to the liver the effluent was
Group 1: After injection of 100 cc. of the effluent, the venous pressure underwent a transient increase in all 5 dogs and then varied within normal limits. In 2 dogs there was a transient decrease of from 10 to 15 mm. Hg in the systolic blood pressure, but in the remaining dogs there was no significant change in arterial pressure over a 30-minute period. Group 2: In one dog from this group there was a drop in blood pressure from 210 to 180 mm. Hg systolic. In the other 4 dogs, there were normal variations in venous and arterial pressures over a 30-minute period, none of which was significant. Grotlj-, 3: In this series of 5 dogs, severe, sustained hypotension (a 60 to 90 mm. Hg drop for a period of from 18 to 61 min.) occurred 4 minutes after infusion of the effluent. Group, 4: In this group there was only a transient increase in venous pressure (from 4 to 5 cm. of water). The systolic blood pressure varied within normal limits. Group 5: Following injection of 100 cc. of the plasma fraction, there was a transient increase of venous pressure in 7 dogs. In 4 of the dogs that received normothermic effluent the systolic arterial pressure dropped from 70 to 90 mm. Hg, and this persisted for periods varying from 17 to 54 minutes. In 3 of the dogs that received hypothermic effluent (33°C.) the systolic blood pressure dropped from 60 to 70 mm. Hg for a period ranging from 17 to 41 minutes. In the remaining 8 dogs that received 50 cc. of the plasma fraction of the effluent there was a transient increase in venous pressure. In the four that received a normothermic infusion, the systolic pressure dropped from 70 to 90 mm. Hg for a period varying between 30 and 60 minutes. In the 4 that received hypothermic effluent the hypotensive pressure fall varied between 40 and 55 mm. Hg and lasted from 16 to 45 minutes.
JOSEPH
ANALYSIS
OF THE EFFLUENT
ET
AL.:
VENOUS
The following determinations of the hepatic venous e&rent were made: temperature, serum electrolytes, bilirubin, alkaline phosphatase, liver enzymes, pH, pCO-, blood glucose, and bacterial cultures. Figure 2 shows the variations in serum electrolytes in the venous effluent among the 35 dogs. The sodium levels ranged from 140 to 158 mE1. per liter with an average value of 147. Potassium values ranged from 4.7 to S.9 mEc1. per liter with a mean of 5.33. The serum chloride ranged from 102.8 to 117.6 mEq. per liter with an average value of 111.5 mEq. per liter. The CO, varied from 10.7 to 22.6 mEq. per liter with an average of 18.8. No striking variations in any of the electrolyte values studied could be found to account for the hypotension which developed. There were, however, four instances in which the CO, value was less than 14 mEq. per liter. In each instance the venous effluent had had a low pH. An equally prolonged hypotension couId be produced, however, even with injection of a venous effluent, with a more normal pH and CO:! value. Variations in the pH, pCO?, and liver enzymes of the effluent were also recorded. The pC0, varied between 4S and 61 mm. with an average value of 52.3 mm. The pH ranged from 6.9 to 7.4 with an average of 7.2. Hypotension could be produced even with relatively normal values in these parameters. In
VASODEPRESSIPE
EFFECTS
OF
THE
VENOUS
EFFLUEKT
all dogs there was a moderate increase in the liver transaminase. The SGOT values varied between 221 and 1,530 units, and the SGPT values varied between 99 and 1,590 units. In dogs that had a prolonged ischemia time before revascularization of the transplanted liver and that received normothermic effluent, the transaminase levels were greatly elevated. Aerobic and anaerobic bacterial cultures of the effluent were examined in all cases and pathogenic organisms were cultured from the effluent in nine cases. Bacterial studies on effluent yielded the following results: sterile, 26; Alcaligenes fuecalis, 3; Escllerichia coli, 2; Pseudomonas aeruginosu, 2; and Staphylococcus aureus, 2. Prolonged hypotension resulted even with infusion of sterile effluent. Bilirubin values of the effluent varied between 0.2 and 0.7 mg. percent. The alkaline phosphatase varied between 0.3 to 3.2 King Armstrong units. Glucose levels of the effluent varied from 210 to 681 mg. percent and correlated with the amount of glucose present in the perfusion solution prior to transplantation of the liver. Table 1 shows the changes following infusion of the plasma fraction of the effluent. The severity and duration of the hypotension were greatly extended with a normothermic effluent. The duration of ischemia in the transplanted liver varied between 39 and 121 minutes. The length of hepatic anoxia, however, prior to transplantation, did not correlate with the duration or severity of the hypotension.
22 co2
m-q/l clmEq//
‘8
14 10 -1, , , I. : I / >.I~,LLLLU LL-I 1111-1 1. .-I 1 11 114 110 106
102
i[ I 11_,LUI~LLu.II
Mlw--I
ILLIL.
1 -_.
# Fig, 2. Variations in serum electrolytes in venous effluent administered to dogs in study. DOG
DISCUSSION Various factors may explain the systemic hypotension that follows revascularization of the transplanted liver: (1) pooling of blood in the newly vascularized liver, (2) pooling of blood in the splanchnic circulation, (3) proliferation of bacteria in the anoxic liver, (4) accumulation and sudden release of metabolic products secondary to hepatic anoxia, and (5) the presence of a vasodilatory product. (1) The pooling or sequestration of the blood in the newly vascularized liver has 369
7 8 9 10 11 12 13 14 15
Dog 1 2 3 4 5
;i 50 50 50 50
100 50 50
Amount of Effluent Infused (cc. ) 100 100 100 100 100 33 37 37 37 37 33 33 33 33
Temperature of Effluent (“C.1 37 37 37 37 33
Table
1.
Following
Sterile Sterile A. faecalis Sterile Sterile Sterile Sterile Sterile A. faecalis
Organism Cultured Sterile E. coli Sterile Sterile E. coli S. aweus
Changes
of Plasma
55 39 102 96 103 100 46 89 74 53
Duration of Ischemia Before Revascularization (min.) 71 118 64 73 53
Infusion
Fraction
12 13 to 16 11 to 16 17 to 14 to 12 to 15 12
18 16 14
15
13
Venous Pressure (mm. HaO) 13 15 12 to 14 17 11 to 14
of E@uent
70 65 90 85 78 83 49 55 40 42
Systolic Pressure Drop (mm. Hg) 73 89 75 84 62
41 17 58 49 37 53 45 38 16 27
30 54 27 47 26
Duration of Hypotension (min.)
JOSEPH
ET
AL.:
been suggested as a mechanism for posttransplant hypotension. Drapanas and his associates [4], however, found in isolated perfusion studies that blood transfusion did not improve survival. Starzl and his associates [15] have also observed that vigorous blood replacement before revascularization of the transplanted liver did not obviate the resulting hypotension. This has been our experience as well. (2) A decrease in the effective circulating blood volume by pooling of blood in the splanchnic circulation during implantation of the liver has also been suggested as a mechanism of hypotension [ 17, 181. In this experiment, however, hypotension occurred even if a portacaval shunt was performed. Raff ucci and associates [ 131, investigating this problem in isolated liver perfusion studies, were able to show that with a portacaval shunt, this splanchnic pooling was not seen. (3) The release of bacteria or endotoxins from the transplanted liver has been believed to be a possible etiological mechanism. Markowitz and Rappaport [ll] have shown that bacteria multiply rapidly in the canine liver after ligation of the hepatic artery. Since prolonged and sustained hypotension was induced simply by the injection of sterile effluent in several dogs, the bacterial factor does not appear to be clearly etiological. (4) The accumulation of various metabolites in the transiently anoxic liver has been previously noted. Starzl and others [3, 10, 161 have observed a metabolic acidosis and elevation of SGOT and SGPT in the recipient following liver transplantation. The acidosis probably reflects the production of lactic acid from anaerobic metabolism during hepatic ischemia. There were no changes in the serum electrolytes to account for this hypotension. As shown by Figure 2, however, several dogs experienced a decrease in pH and as well as a pronounced increase in pea, liver enzymes. These changes were not directly related to the length of hepatic ischemia, and the severity of the hypotension did not correlate with the amount of acidosis. Studies of isolated liver perfusion, both in our laboratory [2] and by others [9], have shown
VASODEPRESSIVE
EFFECTS
OF
THE
VENOUS
EFFLUENT
that following hepatic &hernia, infusion of bicarbonate or THAM has only slight, transient influence on the hypotension. Even though hepatic anoxia produces liver cell damage and acidotic venous effluent, the degree of acidosis does not appear to be severe enough to account for the prolonged hypotension that occurs. In the group of dogs in which hypothermic infusion was used to preserve the liver prior to transplantation and in which the effluent gathered was hypothermic, the degree and duration of hypotension were less pronounced. Hypothermia is known to protect the ischemic liver from cellular injury and accumulation of toxic metabolites [ 1, 121. Hypothermia may also be responsible for release of a possible vasodilatory substance. (5) The release of a vasodilatory substance by the hypoxic liver has been previously studied by Shorr and others [14], who isolated a vasodilatory substance after 30 minutes of liver anoxia which resulted in severe arterial hypotension. Following infusion of this material the experimental animal was increasingly refractory to fluid and blood replacement in the treatment of hypotension. The greater the duration of hypoxia, the greater the amount of vasodilatory substance detected, and the hypotension increased rapidly and progressively throughout a 3-hour period. They felt that tissue hypoxia by itself was an adequate explanation for the production of the vasodilatory substance. They were also able to show that in the normal liver this material was detoxified. In the experiments reported on here, with the experimental animal’s own liver circulation excluded, any vasodilatory substance present in the venous effluent could not be detoxified by the liver and was therefore free to produce its effects on the body. In the dogs with an intact liver circulation that received an injection of venous effluent, no significant hypotension occurred. When the liver was excluded from the circulation, injection of the plasma fraction of the effluent was able to produce hypotension. Injection of the erythrocyte cell fraction in the animals with liver exclusion did not produce significant 371
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hypotension. Granick [S] suggested that this vasodilatory mechanism is probably ferritin, an iron-protein compound. Additional studies are being performed in this laboratory to isolate a similar vasoactive substance from the venous effluent.
AUGUST
3.
4.
5
SUMMARY Homotransplantation of the liver necessarily entails variable periods of hepatic anoxia. Hypoxia or direct hepatic trauma at the time of transplantation results in accumulation of toxic metabolites and the release of a vasoactive substance which is capable of producing profound and sustained hypotension. Only minor alterations in serum electrolytes, bilirubin, and alkaline phosphatase are present in the venous effluent gathered from the revascularized liver graft. Serum transaminase levels were in general less elevated when the donor liver was perfused hypothermically and the duration of hepatic ischemia was short. Injection of the plasma fraction from the venous effluent of the revascularized liver graft, with exclusion of the dog’s liver vasculature, resulted in sustained hypotension. Acidotic effluent and bacteria in the effluent were not universally productive of hypotension. The formation of a vasoactive substance from disintegration of liver cells, either due to trauma, anoxia or acidosis, may be responsible for this hypotension. This problem may be partially ob viated by diversion of the accumulated blood in the newly vascularized transplanted liver for a protracted period of time before recirculation in the recipient is permitted. REFERENCES 1.
2.
372
Bernhard, W. F., McMurray, J. B., and Curtis, G. W. Feasibility of partial hepatic resection under hypothermia. New Eng. J. Med. 253:159, 1955. Buckberg, G., Ono, II., Joseph, W. L., Tocornal, J., Fonkalsrud, E. W., and Longmire, W. P., Jr. Hypotension following hepatic inflow stasis: Factors influencing its occurrence and prevention. Surgery (in press).
6
7.
8. 9. 10.
11. 12.
13.
14.
15.
16.
17.
18.
1968 Brown, H., Patel, J., Blair, 1). W., and Brown, M. E. Biochemical studies with preserved transplanted canine liver. J.A.M.A. 196:95, 1966. Drapanas, T., Becker, D. R., Alfano, G. S., Potter, W. H., and Steward, J. D. Some effects in interrupting hepatic blood flow. Ann. Surg. 142:831, 1955. Fonkalsrud, E. W., Ono, H., Shafey, 0. A., Joseph, W. L., Tocornal, J., and Longmire, W. P., Jr. Allogeneic canine liver transplantation using cadaver donors. Sqery ( in press ) . Fonkalsrud, E. W., Ono, H., Shafey, 0. A., and Longmire, W. P., Jr. Orthotopic canine liver homotransplantation without vena caval interruption. Snrp. Gynec. O&et. (in press), Goodrich, E. O., Jr., Welch, H. F., Nelson, J., Beecher, T. S., and Welsh, C. S. Homotransplantation of the canine liver. Surgery 39:244, 1956. Granick, S. Structure and functions of ferritin. Physiol. Rcu. 31:489, 1951. Jolly, P. C., and Foster, J. H. Hepatic inflow stasis. Sqery 54:45, 1963. Marchioro, T. L., Huntley, R. T., Wnddell, W. R., and Starzl, T. E. Extracorporeal perfusion for obtaining postmortem homografts. Szcrgery 54:900, 1963. Markowitz, J., and Rappaport, A. M. The hepatic artery. Physiol. Rev. 31:188, 1951. Mito, M., Tamaki, A., Kon, T., Ohira, S., and Kikami, J. Experimental studies on differential hypothermia of the liver. J. Szlrg. Res. 5:207, 1965. Raffucci, F. L., Lewis, F. J., and Wangensteen, 0. H. Hypothermia in experimental hepatic surgery. PTOC. Sot. Exp. Biol. Med. 83:639, 1953. Shorr, E., Zweifach, B. W., and Furchgott, R. On the occurrence, sites and modes of origin F. and destruction of principles affecting the compensatory vascular mechanisms in experimental shock. Science 102:489, 1945. Starzl, T. E., Kaupp, H. A., Jr., Brock, D. R., Lazarus, R. E., and Johnson, K. V. Reconstructive problems in canine liver homotransplantation with special reference to the postoperative role of hepatic venous flow. Surg. Gynec. Obstet. 111:733, 1960. Starzl, T. E., Marchioro, T. L., VonKaulla, K. N., Hermann, G., Brittain, R. S., and Waddell, W. R. Homotransplantation of the liver in humans. Surg. Gynec. O&et. 117:659, 1963. State, D., and Lichtenstein, L. A study of the genesis of shock associated with experimentally induced hepatic necrosis in dogs. Surgery 39:12, 1956. State, D., Rauch, R., and Muller, J. J. The experimental production of the hepatorenal svndrome in dogs. Surg. Forrrnr 2:171, 1950. .
EFFECTS OF THE VENOUS EFFLUENT CANINE LIVER ALLOTRANSPLANTATION L.
AND
JOSEPH,
M.D.,
WILLIAM
ERIC P.
SYSTEMIC HYPOTENSION has been observed to follow revascularization of the transplanted canine liver. Although the etiology of this phenomenon remains unclear, it has been suggested that release of hepatic metabolites into the general circulation or that hypovolemia secondary to pooling of blood, either in the transplanted liver or the splanchnic circulation, may be the cause. Prophylactic administration of blood before and during revascularization does not obviate this complication [7, 9, 15, 171. The study reported here was designed to examine the venous effluent which pools in the transplanted liver immediately following revascularization, in order to quantitate metabolic changes and isolate “vasoactive” substances which might induce hypotension.
MATERIALS
AND
METHODS
The techniques of orthotopic and heterotopic liver transplantation have been described in previous reports [5, 61. After the From the Department of Surgery, UCLA School Medicine, Los Angeles, Calif. *lohn and Maw R. Markle Scholar in Academic Me&cine. ’ This work was supported in part by U.S. Public Health Service Training Grant GM 1559, and a Grant from the Califorgia Institute for Cancer Research. Submitted for publication July 27, 1967.
of
W.
LONGMIRE,
FONKALSRUD, JR.,
M.D.,* M.D.
donor liver was excised, a large plastic cannula was placed in the infrahepatic vena cava to be used for decompression upon revascularization of the transplanted liver (Fig. 1). After the vena cava and hepatic artery anastomoses were completed and after flow to the artery was restored, the venous effluent was allowed to drain by gravity through the cannula into sterile heparinized bottles. The vena caval anastomosis was occluded during the period in which the effluent was collected (from 10 to 15 min.). Thirty-five mongrel dogs, weighing from 14 to 21 kg., were used to assess the toxic effects of the venous effluent. They were fed regular kennel rations preoperatively and were immunized against hepatitis and distemper. Sterile technique was used throughout the experiment. The animals were anesthetized with intravenous sodium pentothal and intubated, and anesthesia was maintained with a light nitrous oxide-oxygen mixture. The left femoral vein was cannulated for infusion of the effluent. The left femoral artery was cannulated to record the blood pressure with a Statham strain-gauge transducer. The right jugular vein was cannulated for constant measurement of central venous pressure. Each dog was monitored for a period of from 10 to 20 minutes to allow equilibration of pressures. The dogs were divided into five groups, depending upon the amount and frac367
JOURNAL
OF
SURGICAL
RESEARCH
VOL.
8
NO.
8,
AUGUST
1968
again injected. In 7 dogs 100 cc. of the plasma fraction were injected; in the other 8 dogs, 50 cc. of the plasma fraction were infused.
RESULTS
Fig. 1. Technique of collecting hepatic effluent following partial revascularization allograft.
venous of liver
tion of the effluent and the type of operative procedure performed. Group 1: An exploratory laparotomy was performed on 5 dogs and 100 cc. of the hepatic venous effluent were injected. Group 2: A portacaval shunt was performed on 5 dogs. After stabilization of the arterial and venous pressures 100 cc. of the effluent were injected into each dog. Group 3: In another group of 5 dogs, a portacaval shunt was performed and followed by occlusion of the hepatic artery, the afferent loop of the portacaval shunt, and the hepatic veins. After the vital signs had been stabilized for approximately 15 minutes, 100 cc. of effluent were injected. Grou), 4: The procedure as described in Group 3 was again performed in 5 dogs with occlusion of blood supply to the liver. After stabilization 100 cc. of the erythrocyte fraction of the effluent were infused into each dog. Group 5: In 15 dogs the above procedures were performed again, and after occlusion of the blood supply to the liver the effluent was
Group 1: After injection of 100 cc. of the effluent, the venous pressure underwent a transient increase in all 5 dogs and then varied within normal limits. In 2 dogs there was a transient decrease of from 10 to 15 mm. Hg in the systolic blood pressure, but in the remaining dogs there was no significant change in arterial pressure over a 30-minute period. Group 2: In one dog from this group there was a drop in blood pressure from 210 to 180 mm. Hg systolic. In the other 4 dogs, there were normal variations in venous and arterial pressures over a 30-minute period, none of which was significant. Grotlj-, 3: In this series of 5 dogs, severe, sustained hypotension (a 60 to 90 mm. Hg drop for a period of from 18 to 61 min.) occurred 4 minutes after infusion of the effluent. Group, 4: In this group there was only a transient increase in venous pressure (from 4 to 5 cm. of water). The systolic blood pressure varied within normal limits. Group 5: Following injection of 100 cc. of the plasma fraction, there was a transient increase of venous pressure in 7 dogs. In 4 of the dogs that received normothermic effluent the systolic arterial pressure dropped from 70 to 90 mm. Hg, and this persisted for periods varying from 17 to 54 minutes. In 3 of the dogs that received hypothermic effluent (33°C.) the systolic blood pressure dropped from 60 to 70 mm. Hg for a period ranging from 17 to 41 minutes. In the remaining 8 dogs that received 50 cc. of the plasma fraction of the effluent there was a transient increase in venous pressure. In the four that received a normothermic infusion, the systolic pressure dropped from 70 to 90 mm. Hg for a period varying between 30 and 60 minutes. In the 4 that received hypothermic effluent the hypotensive pressure fall varied between 40 and 55 mm. Hg and lasted from 16 to 45 minutes.
JOSEPH
ANALYSIS
OF THE EFFLUENT
ET
AL.:
VENOUS
The following determinations of the hepatic venous e&rent were made: temperature, serum electrolytes, bilirubin, alkaline phosphatase, liver enzymes, pH, pCO-, blood glucose, and bacterial cultures. Figure 2 shows the variations in serum electrolytes in the venous effluent among the 35 dogs. The sodium levels ranged from 140 to 158 mE1. per liter with an average value of 147. Potassium values ranged from 4.7 to S.9 mEc1. per liter with a mean of 5.33. The serum chloride ranged from 102.8 to 117.6 mEq. per liter with an average value of 111.5 mEq. per liter. The CO, varied from 10.7 to 22.6 mEq. per liter with an average of 18.8. No striking variations in any of the electrolyte values studied could be found to account for the hypotension which developed. There were, however, four instances in which the CO, value was less than 14 mEq. per liter. In each instance the venous effluent had had a low pH. An equally prolonged hypotension couId be produced, however, even with injection of a venous effluent, with a more normal pH and CO:! value. Variations in the pH, pCO?, and liver enzymes of the effluent were also recorded. The pC0, varied between 4S and 61 mm. with an average value of 52.3 mm. The pH ranged from 6.9 to 7.4 with an average of 7.2. Hypotension could be produced even with relatively normal values in these parameters. In
VASODEPRESSIPE
EFFECTS
OF
THE
VENOUS
EFFLUEKT
all dogs there was a moderate increase in the liver transaminase. The SGOT values varied between 221 and 1,530 units, and the SGPT values varied between 99 and 1,590 units. In dogs that had a prolonged ischemia time before revascularization of the transplanted liver and that received normothermic effluent, the transaminase levels were greatly elevated. Aerobic and anaerobic bacterial cultures of the effluent were examined in all cases and pathogenic organisms were cultured from the effluent in nine cases. Bacterial studies on effluent yielded the following results: sterile, 26; Alcaligenes fuecalis, 3; Escllerichia coli, 2; Pseudomonas aeruginosu, 2; and Staphylococcus aureus, 2. Prolonged hypotension resulted even with infusion of sterile effluent. Bilirubin values of the effluent varied between 0.2 and 0.7 mg. percent. The alkaline phosphatase varied between 0.3 to 3.2 King Armstrong units. Glucose levels of the effluent varied from 210 to 681 mg. percent and correlated with the amount of glucose present in the perfusion solution prior to transplantation of the liver. Table 1 shows the changes following infusion of the plasma fraction of the effluent. The severity and duration of the hypotension were greatly extended with a normothermic effluent. The duration of ischemia in the transplanted liver varied between 39 and 121 minutes. The length of hepatic anoxia, however, prior to transplantation, did not correlate with the duration or severity of the hypotension.
22 co2
m-q/l clmEq//
‘8
14 10 -1, , , I. : I / >.I~,LLLLU LL-I 1111-1 1. .-I 1 11 114 110 106
102
i[ I 11_,LUI~LLu.II
Mlw--I
ILLIL.
1 -_.
# Fig, 2. Variations in serum electrolytes in venous effluent administered to dogs in study. DOG
DISCUSSION Various factors may explain the systemic hypotension that follows revascularization of the transplanted liver: (1) pooling of blood in the newly vascularized liver, (2) pooling of blood in the splanchnic circulation, (3) proliferation of bacteria in the anoxic liver, (4) accumulation and sudden release of metabolic products secondary to hepatic anoxia, and (5) the presence of a vasodilatory product. (1) The pooling or sequestration of the blood in the newly vascularized liver has 369
7 8 9 10 11 12 13 14 15
Dog 1 2 3 4 5
;i 50 50 50 50
100 50 50
Amount of Effluent Infused (cc. ) 100 100 100 100 100 33 37 37 37 37 33 33 33 33
Temperature of Effluent (“C.1 37 37 37 37 33
Table
1.
Following
Sterile Sterile A. faecalis Sterile Sterile Sterile Sterile Sterile A. faecalis
Organism Cultured Sterile E. coli Sterile Sterile E. coli S. aweus
Changes
of Plasma
55 39 102 96 103 100 46 89 74 53
Duration of Ischemia Before Revascularization (min.) 71 118 64 73 53
Infusion
Fraction
12 13 to 16 11 to 16 17 to 14 to 12 to 15 12
18 16 14
15
13
Venous Pressure (mm. HaO) 13 15 12 to 14 17 11 to 14
of E@uent
70 65 90 85 78 83 49 55 40 42
Systolic Pressure Drop (mm. Hg) 73 89 75 84 62
41 17 58 49 37 53 45 38 16 27
30 54 27 47 26
Duration of Hypotension (min.)
JOSEPH
ET
AL.:
been suggested as a mechanism for posttransplant hypotension. Drapanas and his associates [4], however, found in isolated perfusion studies that blood transfusion did not improve survival. Starzl and his associates [15] have also observed that vigorous blood replacement before revascularization of the transplanted liver did not obviate the resulting hypotension. This has been our experience as well. (2) A decrease in the effective circulating blood volume by pooling of blood in the splanchnic circulation during implantation of the liver has also been suggested as a mechanism of hypotension [ 17, 181. In this experiment, however, hypotension occurred even if a portacaval shunt was performed. Raff ucci and associates [ 131, investigating this problem in isolated liver perfusion studies, were able to show that with a portacaval shunt, this splanchnic pooling was not seen. (3) The release of bacteria or endotoxins from the transplanted liver has been believed to be a possible etiological mechanism. Markowitz and Rappaport [ll] have shown that bacteria multiply rapidly in the canine liver after ligation of the hepatic artery. Since prolonged and sustained hypotension was induced simply by the injection of sterile effluent in several dogs, the bacterial factor does not appear to be clearly etiological. (4) The accumulation of various metabolites in the transiently anoxic liver has been previously noted. Starzl and others [3, 10, 161 have observed a metabolic acidosis and elevation of SGOT and SGPT in the recipient following liver transplantation. The acidosis probably reflects the production of lactic acid from anaerobic metabolism during hepatic ischemia. There were no changes in the serum electrolytes to account for this hypotension. As shown by Figure 2, however, several dogs experienced a decrease in pH and as well as a pronounced increase in pea, liver enzymes. These changes were not directly related to the length of hepatic ischemia, and the severity of the hypotension did not correlate with the amount of acidosis. Studies of isolated liver perfusion, both in our laboratory [2] and by others [9], have shown
VASODEPRESSIVE
EFFECTS
OF
THE
VENOUS
EFFLUENT
that following hepatic &hernia, infusion of bicarbonate or THAM has only slight, transient influence on the hypotension. Even though hepatic anoxia produces liver cell damage and acidotic venous effluent, the degree of acidosis does not appear to be severe enough to account for the prolonged hypotension that occurs. In the group of dogs in which hypothermic infusion was used to preserve the liver prior to transplantation and in which the effluent gathered was hypothermic, the degree and duration of hypotension were less pronounced. Hypothermia is known to protect the ischemic liver from cellular injury and accumulation of toxic metabolites [ 1, 121. Hypothermia may also be responsible for release of a possible vasodilatory substance. (5) The release of a vasodilatory substance by the hypoxic liver has been previously studied by Shorr and others [14], who isolated a vasodilatory substance after 30 minutes of liver anoxia which resulted in severe arterial hypotension. Following infusion of this material the experimental animal was increasingly refractory to fluid and blood replacement in the treatment of hypotension. The greater the duration of hypoxia, the greater the amount of vasodilatory substance detected, and the hypotension increased rapidly and progressively throughout a 3-hour period. They felt that tissue hypoxia by itself was an adequate explanation for the production of the vasodilatory substance. They were also able to show that in the normal liver this material was detoxified. In the experiments reported on here, with the experimental animal’s own liver circulation excluded, any vasodilatory substance present in the venous effluent could not be detoxified by the liver and was therefore free to produce its effects on the body. In the dogs with an intact liver circulation that received an injection of venous effluent, no significant hypotension occurred. When the liver was excluded from the circulation, injection of the plasma fraction of the effluent was able to produce hypotension. Injection of the erythrocyte cell fraction in the animals with liver exclusion did not produce significant 371
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hypotension. Granick [S] suggested that this vasodilatory mechanism is probably ferritin, an iron-protein compound. Additional studies are being performed in this laboratory to isolate a similar vasoactive substance from the venous effluent.
AUGUST
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SUMMARY Homotransplantation of the liver necessarily entails variable periods of hepatic anoxia. Hypoxia or direct hepatic trauma at the time of transplantation results in accumulation of toxic metabolites and the release of a vasoactive substance which is capable of producing profound and sustained hypotension. Only minor alterations in serum electrolytes, bilirubin, and alkaline phosphatase are present in the venous effluent gathered from the revascularized liver graft. Serum transaminase levels were in general less elevated when the donor liver was perfused hypothermically and the duration of hepatic ischemia was short. Injection of the plasma fraction from the venous effluent of the revascularized liver graft, with exclusion of the dog’s liver vasculature, resulted in sustained hypotension. Acidotic effluent and bacteria in the effluent were not universally productive of hypotension. The formation of a vasoactive substance from disintegration of liver cells, either due to trauma, anoxia or acidosis, may be responsible for this hypotension. This problem may be partially ob viated by diversion of the accumulated blood in the newly vascularized transplanted liver for a protracted period of time before recirculation in the recipient is permitted. REFERENCES 1.
2.
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Bernhard, W. F., McMurray, J. B., and Curtis, G. W. Feasibility of partial hepatic resection under hypothermia. New Eng. J. Med. 253:159, 1955. Buckberg, G., Ono, II., Joseph, W. L., Tocornal, J., Fonkalsrud, E. W., and Longmire, W. P., Jr. Hypotension following hepatic inflow stasis: Factors influencing its occurrence and prevention. Surgery (in press).
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