Retrograde flush following topical cooling is superior to preserve the non-heart-beating donor lung.
OBJECTIVE
The use of non-heart-beating donors (NHBD) has been propagated as an alternative to overcome the scarcity of pulmonary grafts. Formation of microthrombi after circulatory arrest, however, is a major concern for the development of reperfusion injury. We looked at the effect and the best route of pulmonary flush following topical cooling in NHBD.


METHODS
Non-heparinized pigs were sacrificed by ventricular fibrillation and divided into three groups (n=6 per group). After 1h of in situ warm ischaemia and 2.5h of topical cooling, lungs in group I were retrieved unflushed (NF). In group II, lungs were explanted following an anterograde flush (AF) through the pulmonary artery with 50 ml/kg Perfadex (6 degrees C). Finally, in group III, lungs were retrieved after an identical but retrograde flush (RF) via the left atrium. Flush effluent was sampled at intervals to measure haemoglobin concentration. Performance of the left lung was assessed during 60 min in our ex vivo reperfusion model. Wet-to-dry weight ratio (W/D) of both lungs was calculated as an index of pulmonary oedema. IL-1beta and TNF-alpha protein levels in bronchial lavage fluid from both lungs were compared between groups.


RESULTS
Haemoglobin concentration (g/dl) was higher in the first effluent in RF versus AF (3.4+/-1.1 vs 0.6+/-0.1; p<0.05). Pulmonary vascular resistance (dynes x s x cm(-5)) was 975+/-85 RF versus 1567+/-98 AF and 1576+/-88 NF at 60 min of reperfusion (p<0.001). Oxygenation (mmHg) and compliance (ml/cmH(2)O) were higher (491+/-44 vs 472+/-61 and 430+/-33 NS, 22+/-3 vs 19+/-3 and 14+/-1 NS, respectively) and plateau airway pressure (cmH(2)O) was lower (11+/-1 vs 13+/-1 and 13+/-1 NS) after RF versus AF and NF, respectively. No differences in cytokine levels or in W/D ratios were observed between groups after reperfusion. Histology demonstrated microthrombi more often present after AF and NF compared to RF.


CONCLUSIONS
Retrograde flush of the lung following topical cooling in the NHBD results in a better washout of residual blood and microthrombi and subsequent reduced pulmonary vascular resistance upon reperfusion.
Van De Wauwer
Caroline
C
Laboratory for Experimental Thoracic Surgery, University Hospital Gasthuisberg, KU Leuven, Herestraat 49, B-3000 Leuven, Belgium.
Neyrinck
Arne P
AP
Geudens
Nele
N
Rega
Filip R
FR
Verleden
Geert M
GM
Verbeken
Erik
E
Lerut
Toni E
TE
Van Raemdonck
Dirk E M
DE
D000818:Animals; D003080:Cold Temperature; D006454:Hemoglobins / Q000032:analysis; D053583:Interleukin-1beta / Q000032:analysis; D008168:Lung / Q000098:blood supply / Q000737:chemistry / Q000503:physiopathology; D008170:Lung Compliance / Q000502:physiology; D016040:Lung Transplantation; D009926:Organ Preservation / Q000379:methods*; D009929:Organ Size / Q000502:physiology; D010100:Oxygen / Q000502:physiology; D015424:Reperfusion / Q000379:methods; D013552:Swine; D014019:Tissue Donors; D014409:Tumor Necrosis Factor-alpha / Q000032:analysis; D014655:Vascular Resistance / Q000502:physiology
D006454:Hemoglobins; D053583:Interleukin-1beta; D014409:Tumor Necrosis Factor-alpha; D010100:Oxygen