Date on Master's Thesis/Doctoral Dissertation

12-2016

Document Type

Doctoral Dissertation

Degree Name

Ph. D.

Department

Physiology and Biophysics

Degree Program

Physiology and Biophysics, PhD

Committee Chair

Smith, Jason

Committee Co-Chair (if applicable)

Maldonado, Claudio

Committee Member

Maldonado, Claudio

Committee Member

Shuschke, Dale

Committee Member

D'Souza, Stanley

Committee Member

Harbrecht, Brian

Author's Keywords

brain death; resuscitation; direct peritoneal resuscitation; leukocyte infiltration

Abstract

Background: Brain death triggers an inflammatory response that is associated with worse outcomes for recipients of transplanted organs procured from brain dead donors. The intestine has been shown to release inflammatory mediators in other types of shock, but its role is brain death is not well described. Direct peritoneal resuscitation (DPR) improves visceral organ blood flow and has been shown to reduce inflammation after hemorrhagic shock. Better understanding of this inflammatory process within the peripheral organs, the effects of DPR, and the role of the intestine could aid in better resuscitation of potential organ donors. Methods: Male Sprague-Dawley rats were made brain dead by inserting a 4F Fogarty catheter into the skull and slowly inflating the balloon. Rats were resuscitated with normal saline to maintain a mean arterial pressure of 80 mmHg and DPR animals also received an intraperitoneal injection of commercial peritoneal dialysis solution. Rats were sacrificed at zero, two, four, and six hours after brain death. Protein levels were assessed using quantitative ELISA. Flow cytometry and immunohistochemistry were used to quantify neutrophil and macrophage infiltration. Results: Flow cytometry demonstrates that macrophages and neutrophils infiltrate the liver, lungs, kidneys, and heart between four and six hours after brain death. Brain death causes increases in serum levels of inflammatory mediators, as well as markers of intestinal injury, which are reduced by DPR. A detailed examination of the lungs and kidneys showing that inflammatory cytokines, leukocyte adhesion molecules, and macrophages and neutrophils increase sequentially within the tissue after brain death, and that DPR reduces every one of these inflammatory stages. Conclusions: These results suggest that multiple peripheral organs in rats experience an influx of leukocytes between four and six hours after brain death. It appears that increased intestinal permeability contributes to this. Using DPR affects every step of this process by maintaining intestinal blood flow, reducing the release of these pro-inflammatory signals, reducing adhesion molecule expression, and ultimately decreasing the macrophages and neutrophils that move into the tissues. Use of DPR during resuscitation of brain dead patients has the potential to reduce systemic inflammation and provide better organs for transplant.

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