Surfactant treatment in a non-heart-beating donor rat lung transplantation model

Effects of exogenous surfactant on the non-heart-beating donor lung graft in experimental lung transplantation - a stereological study

The use of non-heart-beating donor (NHBD) lungs may help to overcome the shortage of lung grafts in clinical lung transplantation, but warm ischaemia and ischaemia/reperfusion injury (I/R injury) resulting in primary graft dysfunction represent a considerable threat. Thus, better strategies for optimized preservation of lung grafts are urgently needed. Surfactant dysfunction has been shown to contribute to I/R injury, and surfactant replacement therapy is effective in enhancing lung function and structural integrity in related rat models. In the present study we hypothesize that surfactant replacement therapy reduces oedema formation in a pig model of NHBD lung transplantation. Oedema formation was quantified with (SF) and without (non-SF) surfactant replacement therapy in interstitial and alveolar compartments by means of design-based stereology in NHBD lungs 7 h after cardiac arrest, reperfusion and transplantation. A sham-operated group served as control. In both NHBD groups, nearly all animals died within the first hours after transplantation due to right heart failure. Both SF and non-SF developed an interstitial oedema of similar degree, as shown by an increase in septal wall volume and arithmetic mean thickness as well as an increase in the volume of peribron-chovascular connective tissue. Regarding intra-alveolar oedema, no statistically significant difference could be found between SF and non-SF. In conclusion, surfactant replacement therapy cannot prevent poor outcome after prolonged warm ischaemia of 7 h in this model. While the beneficial effects of surfactant replacement therapy have been observed in several experimental and clinical studies related to heart-beating donor lungs and cold ischaemia, it is unlikely that surfactant replacement therapy will overcome the shortage of organs in the context of prolonged warm ischaemia, for example, 7 h. Moreover, our data demonstrate that right heart function and dysfunctions of the pulmonary vascular bed are limiting factors that need to be addressed in NHBD.

Excellent clinical outcomes from a national donation-after-determination-of-cardiac-death lung transplant collaborative

Donation-after-Determination-of-Cardiac-Death (DDCD) donor lungs can potentially increase the pool of lungs available for Lung Transplantation (LTx). This paper presents the 5-year results for Maastricht category III DDCD LTx undertaken by the multicenter Australian National DDCD LTx Collaborative. The Collaborative was developed to facilitate interaction with the Australian Organ Donation Authority, standardization of definitions, guidelines, education and audit processes. Between 2006 and 2011 there were 174 actual DDCD category III donors (with an additional 37 potentially suitable donors who did not arrest in the mandated 90 min postwithdrawal window), of whom 71 donated lungs for 70 bilateral LTx and two single LTx. In 2010 this equated to an "extra" 28% of donors utilized for LTx. Withdrawal to pulmonary arterial flush was a mean of 35.2 ± 4.0 min (range 18-89). At 24 h, the incidence of grade 3 primary graft dysfunction was 8.5%[median PaO(2)/FiO(2) ratio 315 (range 50-507)]. Overall the incidence of grade 3 chronic rejections was 5%. One- and 5-year actuarial survival was 97% and 90%, versus 90% and 61%, respectively, for 503 contemporaneous brain-dead donor lung transplants. Category III DDCD LTx therefore provides a significant, practical, additional quality source of transplantable lungs.

Surfactant alterations following donation after cardiac death donor lungs

The use of lungs from donation after cardiac death (DCD) donors is one of the strategies to increase the donor pool. The aim of this study was to assess the surfactant alterations in DCD donor lungs. Pigs were sacrificed and left untouched for 1 (DCD1), 2 (DCD2) and 3 (DCD3) h. Lungs were then topically cooled with saline for 1, 2 or 3 h to reach a total ischemic time of 4 h. Heart-beating donors (HBD) served as control group. Bronchoalveolar lavage (BAL) samples were assessed for protein levels and surfactant function. Left lungs were prepared for ex-vivo evaluation. Pulmonary vascular resistance (PVR), oxygenation, airway pressure (AWP) and wet-to-dry weight ratio were significantly different between HBD and DCD3 groups (P < 0.05). BAL protein levels were statistically higher in DCD3 compared with HBD group (P < 0.05). Surface tension and surface tension measured at minimal bubble diameter (adsorption) were lower in HBD compared with DCD groups (P < 0.05). Adsorption was also lower in DCD1 compared with DCD2 (P < 0.05). Adsorption and surface tension were correlated with oxygenation and AWP (P < 0.05). This study has shown that lung function deteriorates with increasing warm ischemic time intervals. BAL protein, surface tension, adsorption, peak AWP and PVR increase significantly after 2 h of warm ischemia together with a significant reduction of the ratio PaO(2)/FiO(2).

Early lung transplantation success utilizing controlled donation after cardiac death donors

Donation-after cardiac death (DCD) donor organs have potential to significantly alleviate the shortage of transplantable lungs. However, only limited data so far describes DCD lung transplantation (LTx) techniques and results. This study aims to describe the Alfred Hospital's early and intermediate outcomes following DCD donor LTx. Following careful experimentation and consultation DCD guidelines were created to utilize Maastricht category III lung donors from either the ICU or operating room(OR), with a warm ischemic time(WIT) of <60 min. Between May 2006 and December 2007, 22 referred DCD donors led to 11 attempted retrievals after withdrawal, resulting in 8 actual bilateral LTx (2 donors did not arrest in prescribed period and 1 donor had nonacceptable lungs). ICU WIT = 38.4 min (range 20-54, OR WIT = 12.7 min (11-15), p < 0.05. Post-LTx, 1 pulmonary hypertensive patient required ECMO for PGD3. The mean group pO2/FiO2 ratio at 24 hours was 307.7 (240-507) with an ICU stay of 9.5 days (2-21) and ward stay of 21.5 days (11-76). All 8 survive at a mean of 311 days (10-573) with good performance status and lung function. In conclusion, the use of Maastricht category III lungs for human LTx is associated with acceptable early clinical outcomes.

Non-heart-beating donors

The widespread application of lung transplantation is limited by the shortage of suitable donor organs resulting in longer waiting times for listed patients with a substantial risk of dying before transplantation. To overcome this critical organ shortage, some transplant programs have now begun to explore the use of lungs from circulation-arrested donors, so called non-heart-beating donors (NHBDs). This review outlines the different categories of NHBDs, the relevant published experimental data that support the use of lungs coming from these donors and the clinical experience worldwide so far. Techniques for NHBD lung preservation and pretransplant functional assessment are reviewed. Ethical issues involved in transplanting lungs from asystolic donors are discussed.