Bacterial colonization of the donor lower airways is a predictor of poor outcome in lung transplantation☆

Th-17, monokines, collagen type V, and primary graft dysfunction in lung transplantation

RATIONALE

The pathogenesis of primary graft dysfunction (PGD), a serious complication of lung transplantation, is poorly understood. Human studies and rodent models have shown that collagen type V (col[V]), stimulates IL-17-dependent cellular immunity after lung transplantation.

OBJECTIVES

To determine whether patients with end-stage lung disease develop pretransplant col(V)-specific cellular immunity, and if so, the impact of this response on PGD.

METHODS

Trans-vivo delayed-type hypersensitivity (TV-DTH) assays were used to evaluate memory T-cell responses to col(V) in 55 patients awaiting lung transplantation. Pa(O(2))/Fi(O(2)) index data were used to assess PGD. Univariate risk factor analysis was performed to identify variables associated with PGD. Rats immunized with col(V) or irrelevant antigen underwent lung isografting to determine if prior anti-col(V) immunity triggers PGD in the absence of alloreactivity.

MEASUREMENTS AND MAIN RESULTS

We found that 58.8% (10/17) of patients with idiopathic pulmonary fibrosis, and 15.8% (6/38) of patients without idiopathic pulmonary fibrosis tested while on the wait list for a lung transplant were col(V) DTH positive. Col(V) reactivity was CD4(+) T-cell and monocyte mediated, and dependent on IL-17, IL-1beta, and tumor necrosis factor (TNF)-alpha. Pa(O(2))/Fi(O(2)) indices were impaired significantly 6-72 hours after transplantation in col(V)-reactive versus nonreactive patients. Univariate risk factor analysis identified only preoperative TV-DTH to col(V) and ischemic time as predictors of PGD. Finally, in a rat lung isograft model, col(V) sensitization resulted in significantly lower Pa(O(2))/Fi(O(2)), increased local TNF-alpha and IL-1beta production, and a moderate-to-severe bronchiolitis/vasculitis when compared with control isografts.

CONCLUSIONS

The data suggest that activation of innate immunity by col(V)-specific Th-17 memory cells represents a novel pathway to PGD after lung transplantation.

Detectability of SGM Plus profiles in heart and lungs tissue samples incubated in different environments

The aim of the study was assessment of environmental effect on typeability of AmpFlSTR SGM Plus loci: D3S1358, VWA, D16S539, D2S1338, D81179, D21S11, D18S51, D19S433, TH01, FGA and gender marker amelogenin. Heart and lungs specimens collected during autopsies of five persons aged 20-30 years were incubated at 21 degrees C and 4 degrees C in different environmental conditions, fresh different water and soil conditions. DNA was extracted by organic method from tissue samples collected in 7-day intervals and subsequently typed using AmpFlSTR SGM Plus kit and ABI 310. Incubation at 21 degrees C and prevented air access, as well as in peat soil and in sand favoured faster DNA degradation reflected by decrease in typeability rate. In samples with negative genotyping results no DNA was found by fluorometric quantitation. Decomposed soft tissues are potential material for DNA typing.

Medical management to optimize donor organ potential: review of the literature

PURPOSE

Over the past two decades, the demand for donor organs continues to outpace the number of organs available for transplantation. Parallel with this has been a change in the demographics of organ donors with an increase in older donors and donors with marginal organs as a proportion of the total organ donor pool. Consequently, efforts have been made to improve the medical care delivered to potential organ donors to improve the conversion rate and graft survival of available organs. The purpose of this literature review is to provide updated recommendations for the contemporary management of organ donors after the neurological determination of death in order to maximize the probability of recipient graft survival.

SOURCES

A comprehensive review of the literature obtained through searches of MEDLINE/PubMed, and personal reference files.

PRINCIPAL FINDINGS

Contemporary management of the organ donor after neurological determination of death includes therapies to prevent the detrimental effects of the autonomic storm, the use of invasive hemodynamic monitoring and aggressive respiratory therapy including therapeutic bronchoscopy in marginal heart and lung donors, and the use of hormonal therapy including vasopressin, corticosteroids, triiodothyronine or thyroxine, and insulin for the pituitary failure and inflammation seen in brain dead organ donors. The importance of normalizing donor physiology to optimize all available organs is stressed.

CONCLUSION

Aggressive hemodynamic and respiratory management of solid organ donors, coupled with the use of hormonal therapy improves the rate of conversion and graft survival in solid organ recipients.

Marginal Lung Donors: A Diminishing Margin of Safety?

Lung donor shortages have resulted in the critical appraisal of cadaveric donor acceptability criteria and the gradual relaxation of once strict guidelines. Many centers have reported their results with these "extended criteria" donors and an increasing number of multicenter registry studies have also been published. The results have been contradictory and leave many questions unanswered. Important new data has however come to light since the last review of the subject by the International Society for Heart and Lung Transplantation Pulmonary Council. We review the current literature focusing on recent developments in the pursuit of an expanded lung donor pool with acceptable outcomes.

Ex Vivo Evaluation of Nonacceptable Donor Lungs

BACKGROUND

Only a minority of the potential candidates for lung donation are considered suitable, using current evaluation methods. A new method for ex vivo evaluation, with the potential for reconditioning of marginal and nonacceptable lungs, has been developed. This is a report of the ex vivo evaluation of six donor lungs deemed nonacceptable (arterial oxygen pressure less than 40 kPa) by the Scandiatransplant, Eurotransplant, and UK transplant organizations.

METHODS

The lungs are perfused ex vivo with Steen solution, a lung evaluation-preservation solution, mixed with red blood cells to a hematocrit of 15%. This extracellular solution is designed to have an optimal colloid osmotic pressure so that physiologic pressure and flow can be maintained without development of pulmonary edema. An oxygenator connected to the extracorporeal circuit maintains a normal mixed venous blood gas level in the perfusate. The lungs are ventilated and evaluated through analyses of pulmonary vascular resistance, oxygenation capacity, and arterial carbon dioxide pressure minus end-tidal carbon dioxide difference.

RESULTS

The arterial oxygen pressure (inspired oxygen fraction, 1.0) increased from 27 kPa (range, 17 to 34 kPa) in situ in the organ donor at the referring hospital to 57 kPa (range, 39 to 66 kPa) during the ex vivo evaluation. The pulmonary vascular resistance varied from 3.2 to 5.7 Wood units, and the arterial carbon dioxide pressure minus end-tidal carbon dioxide difference was in the range of 1 to 2.5 kPa.

CONCLUSIONS

The arterial oxygen pressure improves significantly in this model. This ex vivo evaluation model is a valuable addition to the armamentarium in finding acceptable lungs in a donor population with inferior arterial oxygen pressure values.

Risk factors for primary graft dysfunction after lung transplantation

OBJECTIVE

The International Society for Heart and Lung Transplantation has proposed a new grading system for primary graft dysfunction based on the ratio of arterial oxygen to fraction of inspired oxygen measured within 48 hours after lung transplantation. Worsening primary graft dysfunction grade is associated with increased operative mortality rates and decreased long-term survival. This study evaluated donor and recipient risk factors for postoperative International Society for Heart and Lung Transplantation grade 3 primary graft dysfunction.

METHODS

We reviewed donor and recipient medical records of 402 consecutive lung transplantations performed between 1992 and 2004. We calculated a worst International Society for Heart and Lung Transplantation primary graft dysfunction grade in the first 48 hours postoperatively. Severe primary graft dysfunction (International Society for Heart and Lung Transplantation grade 3) was defined by a ratio of arterial oxygen to fraction of inspired oxygen of less than 200. Associations of potential risk factors with grade 3 primary graft dysfunction in the first 48 hours postoperatively were examined through bivariate and multivariate analysis.

RESULTS

The 90-day mortality rate associated with the development of International Society for Heart and Lung Transplantation grade 3 primary graft dysfunction in the first 48 hours postoperatively was 17% versus 9% in the group without grade 3 primary graft dysfunction. Significant bivariate risk factors associated with this end point were increasing donor age, donor smoking history of more than 10 pack-years, early transplantation era (1992-1998), increasing preoperative recipient pulmonary artery pressure, and recipient diagnosis. In the multivariate analysis only recipient pulmonary artery pressure, donor age, and transplantation era were associated with grade 3 primary graft dysfunction in the first 48 hours postoperatively at a P value of less than .05.

CONCLUSIONS

Our analysis of donor and recipient risk factors for severe primary graft dysfunction identified patient groups at high risk for poor outcomes after lung transplantation that might benefit from treatments aimed at reducing reperfusion injury.

High Donor Age, Low Donor Oxygenation, and High Recipient Inotrope Requirements Predict Early Graft Dysfunction in Lung Transplant Recipients

BACKGROUND

Early dysfunction in lung transplants is characterized by poor oxygenation, which may then lead to prolonged mechanical ventilation. This may be due to a combination of donor, recipient, and management factors. Our aim was to determine the incidence and severity of hypoxia and graft dysfunction and which factors were directly associated with poor oxygenation within the first 24 hours after lung transplantation.

METHODS

A retrospective study of all 128 lung transplants between 1999 and 2002 was undertaken. Multiple linear regression analysis was performed to determine which donor, recipient, operative, and intensive care unit (ICU) parameters were associated with the worst recorded arterial blood gas partial pressure of oxygen (PAO2)/fraction of inspired oxygen (FIO2) ratio in the initial 24 hours after operation.

RESULTS

Eighty-three percent of the patients (104 of 128) had a PAO2/FIO2 ratio below 300 within the first 24 hours post-transplantation, and 60% (77 of 128) had a PAO2/FIO2 ratio below 200. A high donor age (p = 0.004), low donor PAO2 (p = 0.007), and high post-operative inotrope requirements (p = 0.02) were correlated with a low PAO2/FIO2 ratio. Recipient diagnosis, ischemic time, use of cardiopulmonary bypass, fluid balance in the ICU, and cardiac index were not related. There was no difference in the long-term outcomes of patients with high or low PAO2/FIO2 ratios.

CONCLUSIONS

A low PAO2/FIO2 ratio is a common finding in the first 24 hours after lung transplantation. Donor factors such as age and PAO2, and the need for increasing inotrope requirements in ICU predict early graft dysfunction and hypoxia.

Prophylactic strategies before solid-organ transplantation

PURPOSE OF REVIEW

Prophylactic measures prior to organ transplantation are evolving based on recent reports of emerging infectious diseases, as well as an expanded understanding of the epidemiology of familiar infections. This review will highlight developments with potential impact on donor and recipient screening and pretransplant management.

RECENT FINDINGS

Key findings regarding bacterial infections include the lack of utility of mupirocin intranasal decolonization for prevention of Staphylococcus aureus infections after liver transplantation, and the description of transmission of Pseudomonas infection to multiple recipients via an innominate artery graft. The implications of donor bacterial colonization in lung transplantation are further explored. The emergence of non-Candida albicans yeast and non-Aspergillus mold infections may lead to changes in prophylactic strategies. The majority of cystic fibrosis patients have had Aspergillus colonization at some time before transplant; one-quarter of these develop tracheobronchial aspergillosis and anastomotic complications. There are several key developments regarding viral infections. Donor-derived human herpesvirus-8-infected neoplastic cells have been identified in recipients with Kaposi sarcoma. The transmission of human T-cell lymphotropic virus -1 (HTLV-1) to multiple recipients who developed myelopathy underscores the continuing need for donor screening. The striking event of West Nile virus transmission to multiple recipients from a single donor also has raised questions regarding donor screening for this virus. New information on the use of hepatitis B core antibody-positive donor livers, as well as the emergence of hepatitis B virus escape mutants, is discussed. Finally, information on successful retransplantation after BK polyomavirus (BKV) allograft nephropathy is beginning to appear.

SUMMARY

The pretransplant phase continues to be an important time period for screening and intervention in order to reduce the risk of posttransplant infections. Recent findings add to our current understanding of epidemiology and risk stratification; however, more randomized trials are needed.