Lung procurement by low-potassium dextran and the effect on preservation injury. Munich Lung Transplant Group

Improvement of lung preservation -- from experiment to clinical practice

BACKGROUND

Reperfusion injury represents a severe early complication following lung transplantation. Among the pathogenetic factors, the high potassium content of Euro-Collins(reg) solution is discussed.

MATERIAL AND METHODS

In a pig model of orthotopic left-sided lung transplantation we investigated the effect of Euro-Collins solution (EC: n = 6) versus low potassium dextran (LPD: Perfadex: n = 6). Sham-operated (n = 6) animals served as control. Transplant function, cellular energy metabolism and endothelial morphology served as parameters. In a clinical investigation, 124 patients were evaluated following single (EC: n = 31; LPD n = 37) or double (EC: n = 17; LPD n = 39) lung transplantation, whose organs where preserved with EC (n = 48) or LPD (n = 76). Duration of ischemia, duration of ventilation and stay on ICU were registered. Primary transplant function was evaluated according to AaDO(2) values. Cause of early death (30 days) was declared.

RESULTS

Experimental results: After flush with EC and 18 h ischemia, a reduction of tissue ATP content (p < 0.01 vs inital value and LPD) was noted. Endothelial damage after ischemia was severe (p < 0.05 vs control), paO(2) was significantly decreased.

CLINICAL RESULTS

In the LPD group, duration of ischemia was longer for the grafts transplanted first (SLTx and DLTx: p = 0.0009) as well as second (2. organ DLTx: p = 0.045). Primary transplant function was improved (day 0: SLTx: p = 0.0015; DLTx: p = 0.0095, both vs EC). Duration of ventilation and stay on ICU were shorter (n.s.). Reperfusion injury-associated death was reduced from 8% (EC) to 0 (LPD).

CONCLUSION

In experimental lung preservation, LPD lead to an improved graft function. These results were confirmed in clinical lung transplantation. Clinical lung preservation, therefore, should be carried out by use of LPD.

[Single-lung transplant and primary graft failure]

OBJECTIVE

To quantify primary graft failure (PGF) and its impact on perioperative and early mortality in single-lung transplant (SLT).

METHOD

We analyzed 35 SLT procedures performed using similar techniques. PGF was defined as a PaO2/FiO2 coefficient lower than 200 mmHg during the first 72 hours or ventilation assistance lasting longer than 5 days attributable to primary lung dysfunction. We defined perioperative mortality as occurring within 30 days of surgery and early mortality within 90 days.

RESULTS

Twenty-five men and 10 women received lungs, 22 for pulmonary fibrosis and 13 for emphysema; the mean age was 53.26 10.77 years. Twenty right SLTs were performed and 15 left SLTs. Twenty-nine donors were men and 6 were women, with a mean age of 29.31 12.33 years. Twenty-six died from cranial trauma, 8 from stroke and 1 from a brain tumor. The mean time of intubation was 1.69 1.35 days. The mean PaO2 was 470.71 70.82 mmHg. The mean time of ischemia was 201.77 62.64 minutes. Four patients (11.42%) developed PGF and 3 died during the perioperative period. Two additional patients died within the early postoperative period. Survival was 91.4% at one month and 85.5% at three months. The cause of donor death was the only variable that influenced the development of PGF.

CONCLUSION

We observed a low incidence of PGF and of perioperative and early mortality, with one and three month survival rates similar to those reported internationally.

Surfactant function in lung transplantation after 24 hours of ischemia: advantage of retrograde flush perfusion for preservation

OBJECTIVE

Surfactant function was shown to be impaired in clinical and experimental lung transplantation. This study was designed to define the impact of retrograde flush perfusion on graft and surfactant function after an extended period of ischemia.

METHODS

Left lung transplantation was performed after 24 hours of graft ischemia in 12 pigs. In half of the grafts antegrade cold flush perfusion (Perfadex) was used for preservation. In the second group grafts were flushed in a retrograde fashion via the left atrium. Graft function was monitored for 7 hours after transplantation. Before transplantation (basal) and after 2 hours of reperfusion, bronchoalveolar lavage fluid was obtained. Minimal surface tension of bronchoalveolar lavage fluid was determined and the ratio of small and large surfactant aggregates was calculated. Lung water content was analyzed online in the reperfusion period.

RESULTS

Right-sided heart failure developed in 2 animals of group 1 (antegrade perfusion) within 2 and 4.5 hours of reperfusion, respectively. All other pigs survived the observation period. PO(2)/FIO(2) (P =.001) and dynamic lung compliance (P =.001) were superior in retrogradely flushed grafts. A comparable increase of minimal surface tension was found after reperfusion in both groups. Small/large surfactant aggregate ratio after reperfusion (P =.03), as well as extravascular lung water content, was higher in the antegrade perfusion group.

CONCLUSION

Retrograde flush perfusion for 24-hour lung preservation with low-potassium dextran (Perfadex) solution led to better initial graft function than the standard antegrade perfusion technique. A moderate impairment of surfactant function was found in both groups, which was more pronounced in the antegrade perfusion group.

Influence of high molecular dextrans on lung function in an ex vivo porcine lung model

BACKGROUND

Extracellular preservation solutions utilizing high molecular agents can reduce intracellular edema during ischemia/reperfusion in lung transplantation. A solution of 40,000 dalton molecular weight (DMW) has already been clinically established (Perfadex). However, it is unclear whether dextrans of this particular size represent the optimal additive for lung preservation solutions.

MATERIALS AND METHODS

In a new ex vivo porcine lung model, lungs were each preserved with low-potassium solutions containing 5% dextran with 90,000 DMW (Dex 90) and 160,000 DMW (Dex 160) and with Perfadex (40,000 DMW). After 24 h of cold ischemia, reperfusion was performed employing a roller pump with a pulsatile module. Lungs were perfused with deoxygenated perfusate and ventilated with room air. The oxygenation capacity (Delta pO(2)), peak inspiratory pressure (PIP), and mean pulmonary artery pressure (PAP) were monitored for 60 min. Net weight gain (NWG) and wet-to-dry ratio (W/D ratio) were determined. Free-radical generation was assessed by measuring malondialdehyde (MDA) at 10, 30, and 50 min.

RESULTS

PIP and PAP increased in all groups significantly during reperfusion. However, Dex 160-perfused lungs exhibited significantly higher values than those with Dex 90 and Perfadex. Perfadex showed the highest Delta pO(2) throughout the entire reperfusion, while Delta pO(2) was slightly reduced in Dex 160 and significantly lower in Dex 90. In Perfadex the lowest water content was observed assessed by NWG and W/D ratio. The highest MDA values were observed in Dex 90, followed by Dex 160, while the lowest values were seen in Perfadex.

CONCLUSIONS

Preservation of the lung with Perfadex exhibited superior postischemic function in contrast to preservation solutions containing dextrans with a higher molecular weight.

Influence of preservation solution on early graft failure in clinical lung transplantation

The aim of this study was to assess the influence of preservation solution type and extra- or intracellular composition on the occurrence of early graft dysfunction after clinical lung transplantation. For 170 patients who underwent a single (n = 124) or bilateral (n = 46) lung transplantation in two centers in Paris between 1988 and 1999, the preservation technique applied to the donor lung was single-flush perfusion of the pulmonary artery with one of several solutions of intracellular (Euro-Collins, n = 61; University of Wisconsin, n = 24) or extracellular composition (Cambridge, n = 64; Celsior, n = 21). The early postoperative outcome of these patients was reviewed. Reimplantation edema occurred in 48% of all patients, and the overall 1-mo survival rate was 84%. No significant difference in the incidence of edema, duration of mechanical ventilation, and 1-mo survival rate was observed between the four groups or between intra- and extracellular groups. After adjustment for graft ischemic time by means of multivariate analysis, the use of extracellular preservation fluid was associated with a lower incidence of reimplantation edema without effect on 1-mo mortality. Graft ischemic time was associated with both edema occurrence and 1-mo survival rate (p = 0.02 and p = 0.01, respectively). We conclude that extracellular-type solutions are associated with better lung preservation than intracellular-type solutions in clinical transplantation.

Flush perfusion with low potassium dextran solution improves early graft function in clinical lung transplantation

OBJECTIVES

We have previously demonstrated experimentally an amelioration of reperfusion injury of the lung after preservation using low potassium dextran (LPD) solution compared to Euro-Collins (EC) solution. Now we report on early graft function in 106 lung transplant recipients of LPD or EC preserved grafts.

METHODS

Initial graft function was assessed by measurement of lung compliance and oxygenation index 2 h after transplantation. Length of stay on the intensive care unit and hours of mechanical ventilation were compared. Correlation of donor oxygenation, ischemic time, type of transplant, recipient age and sex as well as initial lung compliance and oxygenation with early postoperative course were calculated.

RESULTS

Dynamic lung compliance was significantly (P<0.05) improved in the LPD group. PO(2)/fiO(2) was comparable in both groups (303+/-122 mmHg LPD, 282+/-118 mmHg EC). Mechanical ventilation was used for 321+/-500 h in the EC group and 189+/-365 h in the LPD group (P=0.006). Intensive care therapy was required for 17.2+/-23.7 days in the EC group and 10.4+/-16 days in the LPD group (P=0.012). Significantly higher lung function parameters were obtained in extubated recipients of LPD preserved grafts 2 weeks after TX. Thirty day graft survival was improved in the LPD group (P=0.045). In the EC group, 30 day mortality was 14.2 and 8% in the LPD group.

CONCLUSIONS

A reduction of perioperative mortality and morbidity suggests that LPD solution has superior early graft function compared to lung preservation using EC solution.

Effects of EP4 solution and LPD solution vs Euro-Collins solution on Na(+)/K(+)-ATPase activity in rat alveolar type II cells and human alveolar epithelial cell line A549 cells

BACKGROUND

Intact alveolar epithelial Na(+)/K(+)- adenosinetriphosphatase (ATPase) function is important in preventing alveolar fluid accumulation after lung transplantation. We examined whether the type of preservation solution used influences Na(+)/K(+)-ATPase activity in alveolar epithelial cells.

METHODS

Rat alveolar type II cells were preserved with EP4, low-potassium dextran (LPD), or Euro-Collins solution at 7 degrees C for 5 and 20 hours. To assess cell toxicity, we measured cell viability and lactate dehydrogenase release. Na(+)/K(+)-ATPase activity was measured as ouabain-sensitive ATPase hydrolysis. We also examined the effect of terbutaline (10(-3) mol/liter) and dibutyryl cyclic adenosine monophosphate (dbcAMP) (10(-3) mol/liter) on Na(+)/K(+)-ATPase activity in A549 cells preserved for 5 hours.

RESULTS

All solutions caused significant damage of rat alveolar type II cells at 20 hours. However, Na(+)/K(+)-ATPase activity was preserved at normal levels with EP4 and LPD over 20 hours. Terbutaline and dbcAMP significantly increased Na(+)/K(+)-ATPase activity in A549 cells preserved with EP4 and LPD solutions for 5 hours. However, we observed no activation in the cells preserved with Euro-Collins solution. We found no significant difference in intracellular cAMP levels after terbutaline challenge among the types of preservation solution.

CONCLUSIONS

We conclude that extracellular-type solutions such as EP4 and LPD may be preferable for maintaining not only the basal activity but also the ability to activate Na(+)/K(+)-ATPase in response to beta-adrenergic agonists, in alveolar epithelial cells.