avaliar o emprego da tcnica de perfuso pulmonar ex vivo ( ppev ) clinicamente com a finalidade de transplante . estudo prospectivo envolvendo o recondicionamento de pulmes limtrofes , definidos por critrios especficos , tais como relao pao2/fio2 < 300 mmhg , com um sistema de ppev . entre fevereiro de 2013 e fevereiro de 2014 , os pulmes de cinco doadores foram submetidos  ppev por at 4 h. durante a ppev , a mecnica pulmonar foi avaliada continuamente . amostras do perfusato foram colhidas a cada hora , assim como foi realizada a avaliao funcional dos rgos . a mdia de pao2 dos pulmes captados foi de 262,9  119,7 mmhg , sendo que , ao final da terceira hora de perfuso , essa foi de 357,0 108,5 mmhg . a capacidade de oxigenao dos pulmes apresentou discreta melhora durante a ppev nas primeiras 3 h ( 246,1  35,1 ; 257,9  48,9 ; e 288,8  120,5 mmhg , respectivamente ) , sem diferenas significativas entre os momentos ( p = 0,508 ) . as mdias de complacncia esttica foram de , respectivamente , 63.0  18,7 ; 75,6  25,4 ; e 70,4  28,0 mmhg aps 1 , 2 e 3 h , com melhora significativa entre a hora 1 e 2 ( p = 0,029 ) , mas no entre a hora 2 e 3 ( p = 0,059 ) . a resistncia vascular pulmonar permaneceu estvel durante a ppev , sem diferenas entre os momentos ( p = 0,284 ) . os pulmes avaliados permaneceram em condies fisiolgicas de preservao ; no entanto , o protocolo no foi efetivo para promover a melhora na funo pulmonar , inviabilizando o transplante . ex vivo lung perfusion ( evlp ) is a novel strategy for reconditioning lungs , with a view to increasing the number of viable organs for transplantation and to reducing the mortality of patients awaiting a transplant . 
 1 
 3 
  the principle of the technique is to replicate the physiological environment that provides the substrates needed to maintain cell metabolism . initially , evlp was described by steen et al . 
 3 
  for the evaluation of non - heart - beating donor lungs , and , subsequently , it was modified for application to the reconditioning of extended - criteria donor lungs by the toronto lung transplant group , in canada . 4 
  lung reconditioning with subsequent transplantation has been employed by various transplant groups , with positive outcomes . 2 
  reported on a series of 20 reconditioned extended - criteria donor lungs in which the pao2/fio2 ratio increased significantly at the end of the reconditioning process ( 2 - 4 h ) . those authors found that the rate of primary graft dysfunction 72 h after transplantation was comparable for both recipients of evlp lungs and recipients of conventionally selected lungs , and that no adverse events were directly attributable to evlp . in other centers , such as those in vienna ( austria ) , paris ( france ) , and turin ( italy ) , the outcomes were similar to those obtained by the toronto group . 
 5 
  despite the positive outcomes , in the united kingdom , a study showed that , of 13 reconditioned lungs , only 6 were transplanted , which represents a utilization rate of 46% . 6 
  the present article reports on the use of evlp clinically to prepare donor lungs for transplantation in brazil . the study was approved by the brazilian national health council - comisso nacional de tica em pesquisa ( conep , brazilian national research ethics committee ; registration no . 16026 ; process no . we used human brain - dead donor lungs that were rejected for conventional transplantation because their pao2/fio2 ratio was < 300 mmhg . between february of 2013 and february of 2014 , there were five lung recoveries for the lung reconditioning protocol . immediately before recovery , bronchoscopic inspection with bal was performed . the bal procedure involved instillation of 40 ml of sterile saline ( 0.9% sodium chloride ) into the segments of the basal pyramid of the right lower lobe , followed by aspiration until approximately 50% of the instilled amount was recovered and stored in a collection vial . the lungs were perfused with perfadex ( vitrolife , gteborg , sweden ) as the preservation solution , stored at 4c in a special bag , and sent to the heart institute surgery center of the university of so paulo school of medicine hospital das clnicas , in the city of so paulo , brazil , to undergo the procedure . the pulmonary artery and pulmonary veins were sutured onto special plastic cannulas , and the lung block was placed in a perfusion chamber ( xvivo perfusion , gteborg , sweden ) . the perfusion system consists of cannulas , a membrane deoxygenator , a heat exchanger , a leukocyte filter , and a centrifugal pump ( maquet , toronto , canada ) . the system is primed with 1.5 l of steen solution ( vitrolife ) , 500 mg methylprednisolone , 500 mg/500 mg imipenem / cilastatin sodium , and heparin ( 3,000 iu ) . the established flow corresponded to 40% of the cardiac output during ventilation at physiological levels : a tidal volume ( vt ) of 6 ml / kg ; a respiratory rate of 7 breaths / min ; a positive end - expiratory pressure of 5 cmh2o ; and an fio2 of 21% . for flow increase , as well as for reheating and ventilation 7 
  perfusion time was set at 4 h , and ventilatory and pulmonary gas exchange parameters were evaluated at the end of each hour . at the end of hour 3 , perfusion was interrupted in the lungs with no prospects of improvement in lung function or respiratory mechanics with a view to transplantation . at evaluation , the ventilator was set at a vt of 10 ml / kg of body weight , a respiratory rate of 10 breaths / min , a positive end - expiratory pressure of 5 cm cmh2o , and an fio2 of 100% . a sample of the perfusate was collected from the outlet of the pulmonary artery and pulmonary vein for blood gas analysis , which measured paco2 , mixed venous carbon dioxide tension , pao2 , mixed venous oxygen tension , lactate levels , and glucose levels . ventilatory parameters measured included peak pressure , plateau pressure , mean airway pressure , static compliance , and vt . the samples were fixed in 10% formalin for 24 h , embedded in paraffin , sectioned on a microtome into 5 m thick slice , and stained with h&e . the presence / absence of pathological changes was investigated under light microscopy by a pathologist . quantitative data are expressed as means and standard deviations . for each variable , the assumption of normal distribution was tested with the shapiro - wilk test . for comparison of means , we used repeated measures anova and the paired student 's t - test . the probability of a type i (  ) error was set at 0.05 for all inferential analyses . descriptive and inferential statistics were calculated using the spss statistics software package , version 21 ( ibm corporation , armonk , ny , usa ) . for comparison of means , we used repeated measures anova and the paired student 's t - test . the probability of a type i (  ) error was set at 0.05 for all inferential analyses . descriptive and inferential statistics were calculated using the spss statistics software package , version 21 ( ibm corporation , armonk , ny , usa ) . the lungs of five donors were submitted to evlp at the heart institute surgery center . however , no transplants were performed , because none of the lungs met the functional criteria for transplantation . four male donors and one female donor were used , and the mean length intubation was 5.6 days . all lungs were obtained from brain - dead donors , because the current legislation in brazil does not allow the use of non - heart - beating donors . the most common cause of death was traumatic brain injury , followed by subarachnoid hemorrhage . the reason the donor lungs were rejected for conventional transplantation was poor blood gas values ( pao2/fio2 ratio = 100% ) . in three cases , discard was associated with radiological changes , and in two cases in which the pao2/fio2 ratio was satisfactory , the lungs were discarded either because of indefinite histology for brain neoplasm ( this being the cause of brain death ) or because the poor clinical condition of the recipient precluded transplantation ( table 1 ) . table 1.characteristics of the selected donors . 
 gender 

 age , years 

 cause of death 

 mv , days 

 pao2 , mmhg 

 donor 
 m18tbi3264,01f50sah7283,02m19tbi362,53m41tbi6334,64m29sah9370,65mv : mechanical ventilation ; m : male ; f : female ; tbi : traumatic brain injury ; and sah : subarachnoid hemorrhage . arterial blood gas sampling with a positive end - expiratory pressure of 5 cmh20 and an fio2 of 100% . mv : mechanical ventilation ; m : male ; f : female ; tbi : traumatic brain injury ; and sah : subarachnoid hemorrhage . arterial blood gas sampling with a positive end - expiratory pressure of 5 cmh20 and an fio2 of 100% . the mean oxygenation capacity ( po2 ) measured during evlp showed little variation , with no statistically significant differences ( figure 1 ) . after 1 , 2 , and 3 h of evlp , respectively , po2 values were 246.1  35.7 mmhg , 257.9  48.9 mmhg , and 288.8  120.5 mmhg ( figure 1 ) . a comparison of the po2 values measured at recovery with those observed at the end of evlp showed that , although the final mean po2 was higher , there were no statistically significant differences ( figure 1 ) . the mean pao2 of the recovered lungs was 262.9  119.7 mmhg at baseline , compared with 357.0  108.5 mmhg after 3 h of evlp . there were no statistically significant differences among the three time points evaluated ( 1 h , 2 h , and 3 h after the initiation of ex vivo perfusion ) . the mean static compliance after 1 , 2 , and 3 h , respectively , was 63.0  18.7 mmhg , 75.6  25.4 mmhg , and 70.4  28.0 mmhg , with a significant difference in results between hour 1 and hour 2 ( p = 0.029).in most of the evlp procedures , the perfusion time was 180 minutes ; in only one case was the perfusion time 240 minutes . a comparative evaluation of the lung biopsy samples collected before and after evlp showed that , in three cases , there was worsening of edema and formation of visible thrombi . the results of bal examination revealed colonization by virulent bacteria with a high potential to cause pulmonary infection in three cases . the evlp technique has been disseminated worldwide , with positive outcomes at various centers . in 2013 , research groups from toronto , vienna , and paris presented their clinical results with evlp at the international society of heart and lung transplantation meeting . 5 
  the results showed that the reconditioned lung utilization rate was high and that the rates of primary graft dysfunction within the first 72 h were low . in the usa , the technique has been validated in a multicenter clinical trial and approved by the food and drug administration . 
 8 
  despite the clearly demonstrated advances , we found discrepancies among the centers regarding the evlp lung utilization rate for transplantation . in the present study , we report the use of evlp at our center . we performed five lung perfusions ; however , evlp was unable to improve lung function because , in general , the recovered lungs showed pronounced physiological changes upon arrival at our surgery center . several factors may be related to the limited number of lung recoveries for evlp in brazil . in our country , organs are obtained only from brain - dead donors . this limitation leads to there being a small supply of lungs for evlp , in comparison with the mean rates of other centers where lungs from non - heart - beating donors are used . reported that 44% of 50 non - heart - beating donor lungs subjected to evlp were used for transplantation in toronto . 1 
  the use of lungs from non - heart - beating donors is well established in the literature , and related data have been compiled into the international society of heart and lung transplantation registry , showing that the use of such lungs results in an increase in the number of transplants . in addition , a multicenter study reported that the outcomes of transplantation of lungs from non - heart - beating donors were similar to those of transplantation of lungs from brain - dead donors , suggesting that transplant teams should make continuous efforts to increase the number of transplants using non - heart - beating donors . 9 
  in our sample , poor blood gas values alone were not the primary cause of donor rejection . the most common reason for donor rejection in 2013 was infection ( in 35% ) , followed by morbidity history ( in 16.7% ) , including smoking and use of inhaled drugs , and blood gas changes ( in 15.6% ) . the evlp lung utilization rate for transplantation varies among the transplant centers that use the evlp technique . the research groups in lund ( sweden ) and in toronto are the most successful , with utilization rates of 67% and 87% , respectively . however , the newcastle group , in the united kingdom , reported a utilization rate of 46% and attributed it to complications related to the quality of the recovered lungs . like the newcastle group , we extended the criteria for donor lung recovery , including those with blood gas changes associated with edema and contusion . 6 
  certainly the limited number of perfusions performed by our group and the inclusion of donor lungs with poor blood gas values associated with other changes had a significant impact on our utilization rate . the use of extended - criteria donor lungs resulted in a greater likelihood of dysfunctions , such as infection , alveolar infiltrate , excess secretions , and pulmonary embolism , compromising the evlp reconditioning process . the main radiological findings were pulmonary infiltrate ( contusion or congestion ) and infection , confirmed by h&e histology and bal culture at the end of evlp . the comorbidities detected in three lungs by radiological imaging and histopathological analysis before evlp may have negatively impacted reconditioning , given that the functional activity of those lungs did not progress satisfactorily . in addition , histological analysis of the lung tissue at the end of perfusion showed increased edema , thrombus formation , and other vascular changes in these cases . in the fourth case , in which there were mild radiological and histopathological changes , evlp occurred satisfactorily , increasing lung functional indices up to values close to the acceptable threshold for transplantation . regarding growth in bal cultures , we detected colonization by virulent bacteria , with a high potential to cause pneumonia in recipients with suppurative disease , in three donors . at our center , previous studies reported high rates of bal culture positivity in lung donors . a retrospective study reported that , of 49 lungs recovered for conventional transplantation , 31 had positive cultures , mainly for staphylococcus aureus and pseudomonas aeruginosa . 10 
  our database provides evidence that the current situation remains unchanged , given that , in 2013 , 26 of the 27 lungs recovered for conventional transplantation had positive cultures . this underscores the importance of investigation of the specific characteristics of the donors at each center so that possible remedial action can be taken before the use of evlp . postoperative complications related to the development of pneumonia can be prevented by combining evlp and specific prophylactic antibiotic regimens . in one of the cases reported here , we found , on the basis of histopathological results , that the donor had bronchiectasis . in another case , both bronchiectasis and microthrombi had been missed on imaging . in the two cases , although evlp was not satisfactory enough for the reconditioning process , it was important in the diagnosis of the comorbidities . we deem it necessary to use additional imaging modalities , such as ct , as well as early fiberoptic bronchoscopy to minimize the number of pathologically compromised donor lungs . in a case report , machuca et al . reported the use of evlp for the treatment of lungs from a donor with pulmonary thromboembolism , with the addition of a thrombolytic agent to the perfusate , which resulted in improvement in the lungs and subsequent transplantation . 11 
  in an experimental study conducted by our team , we found a significant improvement in arterial blood gas values after 1 h of evlp . 12 
 13 
  however , we highlight some methodological differences relative to the present study , such as the use of an fio2 of 100% throughout perfusion and the use of an open left atrium . in recent years , evlp has proven to be very important in the rehabilitation of extended - criteria donor lungs , increasing the number of transplants performed . often , the severity of the comorbidities inherent in the donor lung has a major impact on the achievement of positive outcomes from the use of the evlp technique . among the various organ procurement centers , there are differences with regard to donor care protocols , that is , there is no consensus regarding thyroid hormone replacement , use of desmopressin ( an antidiuretic hormone analog that has mild vasopressor activity ) , or use of a feeding tube . during the development of our protocol , we found that donor lungs in brazil have a higher rate of complications after brain death than do those available for reconditioning at other centers . the here reported non - utilization of evlp donor lungs for transplantation suggests the need for investigation of the specific characteristics of the donors at our center . such information may be highly relevant to making adjustments to the reconditioning technique so as to meet specific needs more fully , thus increasing the likelihood of success with evlp . therefore , we conclude that , although the evlp technique used at our center contributed to maintaining the lungs under physiological conditions , it did not effectively improve lung function , thus precluding the use of the lungs for transplantation .
objective : to evaluate the use of ex vivo lung perfusion ( evlp ) clinically to prepare donor lungs for transplantation . 
 methods : a prospective study involving evlp for the reconditioning of extended - criteria donor lungs , the criteria for which include aspects such as a pao2/fio2 ratio < 300 mmhg . between february of 2013 and february of 2014 , the lungs of five donors were submitted to evlp for up to 4 h each . during evlp , respiratory mechanics were continuously evaluated . once every hour during the procedure , 
 samples of the perfusate were collected and the function of the lungs was evaluated . 
 results : the mean pao2 of the recovered lungs was 262.9  119.7 mmhg at baseline , compared with 357.0  108.5 mmhg after 3 h of evlp . 
 the mean oxygenation capacity of the lungs improved slightly over the first 3 h of evlp-246.1  35.1 , 257.9  48.9 , and 288.8  120.5 mmhg after 1 , 2 , and 3 h , respectively - without significant differences among the time points ( p = 0.508 ) . 
 the mean static compliance was 63.0  18.7 mmhg , 75.6  25.4 mmhg , and 70.4  28.0 mmhg after 1 , 2 , and 3 h , respectively , with a significant improvement from hour 1 to hour 2 ( p = 0.029 ) but not from hour 2 to hour 3 ( p = 0.059 ) . 
 pulmonary vascular resistance remained stable during evlp , with no differences among time points ( p = 0.284 ) . 
 conclusions : although the lungs evaluated remained under physiological conditions , the evlp protocol did not effectively improve lung function , thus precluding transplantation .