Circulation stabilizing therapy and pulmonary high-resolution computed tomography in a porcine brain-dead model

New Techniques for Optimization of Donor Lungs/Hearts

Injuries sustained by donor heart and lung allografts during the transplantation process are multiple and cumulative. Optimization of allograft function plays an essential role in short- and long-term outcomes after transplantation. Therapeutic targets to prevent or attenuate injury are present in the donor, the preservation process, during transplantation, and in postoperative management of the recipient. The newest and most promising methods of optimizing donor heart and lung allografts are found in alternative preservation strategies, which enable functional assessment of donor organs and provide a modality to initiate therapies for injured allografts or prevent injury during reperfusion in recipients.

Effect of Hypotensive Brain Death on the Donor Liver and Its Mechanism in an Improved Bama Miniature Pig (Sus scrofa domestica) Model

BACKGROUND

We aimed to observe the effect of hypotensive brain death on the donor liver and understand its pathophysiological mechanism in improved pig model.

METHODS

The model was induced using the modified intracranial water sac inflation method in 16 Bama miniature pigs. Effects of hypotensive brain death on liver function and tissue morphology were evaluated via changes in liver function enzyme index, liver tissue alkaline phosphatase levels, hourly bile flow, and liver tissue pathology. Its pathophysiological mechanism was examined on the basis of changes in portal vein blood flow, hepatic artery blood flow, portal venous endotoxin level, and liver tissue cytokine levels.

RESULTS

After model establishment, portal vein blood flow, hepatic arterial blood flow, hourly bile flow, and alkaline phosphatase content in hepatic tissue significantly decreased, and serum aspartate aminotransferase, alkaline phosphatase, and lactate dehydrogenase levels significantly increased. Hematoxylin-eosin staining of liver tissue showed that after model establishment, hepatic tissue injury was gradually aggravated and hepatic cells were irreversibly damaged at 7 hours. Portal vein endotoxin levels significantly increased after brain death. Tumor necrosis factor α, interleukin 1, and endothelin 1 levels in liver tissues significantly increased at 3, 6, and 12 hours after brain death (P < .05), and hypoxia-inducible factor 1-α and nitric oxide levels significantly decreased (P < .05).

CONCLUSIONS

Hepatic injury was progressively aggravated under hypotensive brain death. The mechanism of donor liver injury under hypotensive brain death may involve low liver perfusion, release of intestinal endotoxin and inflammatory factors (eg, tumor necrosis factor α and interleukin 1), decreased hypoxia-inducible factor 1-α, and endothelin 1 and nitric oxide imbalance.

Radiological Analysis of Unused Donor Lungs: A Tool to Improve Donor Acceptance for Transplantation?

Despite donor organ shortage, a large proportion of possible donor lungs are declined for transplantation. Criteria for accepting/declining lungs remain controversial because of the lack of adequate tools to aid in decision-making. We collected, air-inflated, and froze a large series of declined/unused donor lungs and subjected these lung specimens to CT examination. Affected target regions were scanned by using micro-CT. Lungs from 28 donors were collected. Two lungs were unused, six were declined for non-allograft-related reasons (collectively denominated nonallograft declines, n = 8), and 20 were declined because of allograft-related reasons. CT scanning demonstrated normal lung parenchyma in only four of eight nonallograft declines, while relatively normal parenchyma was found in 12 of 20 allograft-related declines. CT and micro-CT examinations confirmed the reason for decline in most lungs and revealed unexpected (unknown from clinical files or physical inspection) CT abnormalities in other lungs. CT-based measurements showed a higher mass and density in the lungs with CT alterations compared with lungs without CT abnormalities. CT could aid in the decision-making to accept or decline donor lungs which could lead to an increase in the quantity and quality of lung allografts.

Closed-Loop Prevention of Hypotension in the Heartbeating Brain-Dead Porcine Model

Objective: The purpose of this paper is to demonstrate feasibility of a novel closed-loop controlled therapy for prevention of hypertension in the heartbeating brain-dead porcine model.

METHODS

Dynamic modeling and system identification were based on in vivo data. A robust controller design was obtained for the identified models. Disturbance attenuation properties and reliability of operation of the resulting control system were evaluated in vivo.

RESULTS

The control system responded both predictably and consistently to external disturbances. It was possible to prevent mean arterial pressure to fall below a user-specified reference throughout 24 h of completely autonomous operation.

CONCLUSION

Parameter variability in the identified models confirmed the benefit of closed-loop controlled administration of the proposed therapy. The evaluated robust controller was able to mitigate both process uncertainty and external disturbances.

SIGNIFICANCE

Prevention of hypertension is critical to the care of heartbeating brain-dead organ donors. Its automation would likely increase the fraction of organs suitable for transplantation from this patient group.

Safe orthotopic transplantation of hearts harvested 24 hours after brain death and preserved for 24 hours

Objectives. The aim of this study was to demonstrate safe orthotopic transplantation of porcine donor hearts harvested 24 hours after brain death and preserved for 24 hours before transplantation. Design. Circulatory normalization of brain dead (decapitated) pigs was obtained using a new pharmacological regimen (n = 10). The donor hearts were perfused at 8 °C in cycles of 15 min perfusion followed by 60 min without perfusion. The perfusate consisted of an albumin-containing hyperoncotic cardioplegic nutrition solution with hormones and erythrocytes. Orthotopic transplantation was done in 10 recipient pigs after 24 hours’ preservation. Transplanted pigs were monitored for 24 hours, then an adrenaline stress test was done. Results. All transplanted pigs were stable throughout the 24-hour observation period with mean aortic pressure around 80 mmHg and normal urine production. Mean right and left atrial pressures were in the range of 3–6 and 5–10 mmHg, respectively. Blood gases at 24 hours did not differ from baseline values. The adrenaline test showed a dose dependent response, with aortic pressure increasing from 98/70 to 220/150 mmHg and heart rate from 110 to 185 beats/min. Conclusion. Orthotopic transplantation of porcine hearts harvested 24 hours after brain death and preserved for 24 hours can be done safely.