Supraceliac aortic clamping during the anhepatic phase of experimental orthotopic liver transplantation

Relationship Between Patients With or Without a History of Esophageal Varices Bleeding and the Changes in Hemodynamics During Inferior Vena Cava Clamping in Living Donor Liver Transplantation

BACKGROUND

Whether the history of esophageal variceal bleeding (EVB) can be used clinically to predict the tolerability or hemodynamic instability during clamping of the inferior vena cava (IVC) and portal vein in liver transplantation is unknown and, therefore, needs to be elucidated.

PATIENTS AND METHODS

A total of 50 anesthesia charts of patients who underwent living donor liver transplantation were reviewed, analyzed and compared retrospectively. Patients without a history of EVB were classified as group 1 and patients with a history of EVB were classified as group 2. The numbers of patients with a decrease in cardiac index (CI) of ≥20%, ≥30%, or ≥40% from their preclamping values after IVC clamping were compared with a χ(2), and a P value of .05 was regarded as statistically significant.

RESULTS

The measured hemodynamic parameters before and 5 minutes after clamping of the IVC and portal vein were all significantly different in comparison with the patient's preclamping values. The incidence of a decrease in CI of ≥20%, ≥30%, or ≥40% 5 minutes after clamping of the IVC and portal vein were not significantly different between groups.

CONCLUSIONS

Clamping of the portal vein and IVC without performing veno-venous bypass in living donor liver transplantation had a significant negative impact on CI in both groups due to the drastic reduction in the venous return. Statistical analysis revealed that a history of EVB affects hemodynamics in a manner similar to that in patients without history of EVB during IVC clamping.

Effects of ischemic preconditioning in a pig model of large-for-size liver transplantation

OBJECTIVE

In most cases of pediatric liver transplantation, the clinical scenario of large-for-size transplants can lead to hepatic dysfunction and a decreased blood supply to the liver graft. The objective of the present experimental investigation was to evaluate the effects of ischemic preconditioning on this clinical entity.

METHODS

Eighteen pigs were divided into three groups and underwent liver transplantation: a control group, in which the weights of the donors were similar to those of the recipients, a large-for-size group, and a large-for-size + ischemic preconditioning group. Blood samples were collected from the recipients to evaluate the pH and the sodium, potassium, aspartate aminotransferase and alanine aminotransferase levels. In addition, hepatic tissue was sampled from the recipients for histological evaluation, immunohistochemical analyses to detect hepatocyte apoptosis and proliferation and molecular analyses to evaluate the gene expression of Bax (pro-apoptotic), Bcl-XL (anti-apoptotic), c-Fos and c-Jun (immediate-early genes), ischemia-reperfusion-related inflammatory cytokines (IL-1, TNF-alpha and IL-6, which is also a stimulator of hepatocyte regeneration), intracellular adhesion molecule, endothelial nitric oxide synthase (a mediator of the protective effect of ischemic preconditioning) and TGF-beta (a pro-fibrogenic cytokine).

RESULTS

All animals developed acidosis. At 1 hour and 3 hours after reperfusion, the animals in the large-for-size and large-for-size + ischemic preconditioning groups had decreased serum levels of Na and increased serum levels of K and aspartate aminotransferase compared with the control group. The molecular analysis revealed higher expression of the Bax, TNF-alpha, I-CAM and TGF-beta genes in the large-for-size group compared with the control and large-for-size + ischemic preconditioning groups. Ischemic preconditioning was responsible for an increase in c-Fos, IL-1, IL-6 and e-NOS gene expression.

CONCLUSION

Ischemia-reperfusion injury in this model of large-for-size liver transplantation could be partially attenuated by ischemic preconditioning.

A simplified experimental model of large-for-size liver transplantation in pigs

OBJECTIVE

The ideal ratio between liver graft mass and recipient body weight for liver transplantation in small infants is unknown; however, if this ratio is over 4%, a condition called large-for-size may occur. Experimental models of large-for-size liver transplants have not been described in the literature. In addition, orthotopic liver transplantation is marked by high morbidity and mortality rates in animals due to the clamping of the venous splanchnic system. Therefore, the objective of this study was to create a porcine model of large-for-size liver transplantation with clamping of the supraceliac aorta during the anhepatic phase as an alternative to venovenous bypass.

METHOD

Fourteen pigs underwent liver transplantation with whole-liver grafts without venovenous bypass and were divided into two experimental groups: the control group, in which the weights of the donors were similar to the weights of the recipients; and the large-for-size group, in which the weights of the donors were nearly 2 times the weights of the recipients. Hemodynamic data, the results of serum biochemical analyses and histological examination of the transplanted livers were collected.

RESULTS

The mortality rate in both groups was 16.5% (1/7). The animals in the large-for-size group had increased serum levels of potassium, sodium, aspartate aminotransferase and alanine aminotransferase after graft reperfusion. The histological analyses revealed that there were no significant differences between the groups.

CONCLUSION

This transplant method is a feasible experimental model of large-for-size liver transplantation.

Hemodynamic alterations during orthotopic liver experimental transplantation in pigs

PURPOSE

To describe the hemodynamic alterations during orthotopic liver transplantation in pigs.

METHODS

In the period from April 2004 to December 2005, forty-four female Landrace pigs, weighting between 32 and 38 Kg underwent orthotopic liver transplantation. The animals were divided into two groups, donor and recipient pairs, which received whole liver grafts. The surgical procedure was divided into four parts: harvested, back-table, hepatectomy of the recipient and implantation. We analyzed heart rate, blood gas, mean systemic arterial pressure (MAP-mmHg), central venous pressure, pH, Na-, K+, Cl-, Ca+ and urinary output.

RESULTS

The mean anhepatic time was 69 min, cold ischemia was 252.2 min and back-table was 56.6 min. Blood pressure and heart rate dropped significantly during anhepatic phase and after revascularization. Blood gas and electrolytes alterations were observed during anhepatic and reperfusion phases. Although alterations were noted during these phases, the hemodynamic status was recovered and stabilized in the end of the surgery.

CONCLUSIONS

Simplified technique of liver transplant was achieved and description of hemodynamic alterations was possible in pigs.

Systemic and regional effects of supraceliac aortic occlusion during experimental hepatic vascular exclusion

BACKGROUND

Supraceliac aortic occlusion (AO) has been recommended to avoid hypotension during hepatic vascular exclusion (HVE). We hypothesized that AO may negatively affect splanchnic perfusion during HVE.

METHODS

Twenty-six dogs (16 +/- 0.3 kg) were randomly assigned to HVE (n = 13) or HVE+AO (n = 13), during 30 minutes followed by a 60-minute reperfusion period. Cardiac output (CO), mean arterial pressure (MAP), superior mesenteric artery blood flow (SMABF, ultrasonic flowprobe), gastric mucosal PCO(2) (gas tonometry) and PCO(2)-gap were evaluated.

RESULTS

HVE alone induced decreases in MAP from 115 +/- 5.1 to 26 +/- 1 mm Hg, in CO from 2.0 +/- 0.1 to 0.4 +/- 0.1 L/min and SMABF from 398 +/- 42 to 16 +/- 7.6 mL/min, while PCO(2) gap increased from 4 +/- 3.7 to 52 +/- 5.4 mm Hg. Supraceliac aortic occlusion only avoided severe hypotension. During reperfusion MAP, CO, and SMABF were partially restored, while PCO(2) gap showed no improvements in either group.

CONCLUSIONS

HVE promotes major systemic and splanchnic perfusional derangement. Concomitant AO may avoid HVE-induced hypotension without producing further deleterious effects.