Extracorporeal life support after heart or lung transplantation

How to prevent venous cannula orifice obstruction during extracorporeal circulation

Venous cannula orifice obstruction is an underestimated problem during augmented cardiopulmonary bypass (CPB), which can potentially be reduced with redesigned, virtually wall-less cannula designs versus traditional percutaneous control venous cannulas. A bench model, allowing for simulation of the vena cava with various affluent orifices, venous collapse and a worst case scenario with regard to cannula position, was developed. Flow (Q) was measured sequentially for right atrial + hepatic + renal + iliac drainage scenarios, using a centrifugal pump and an experimental bench set-up (afterload 60 mmHg). At 1500, 2000 and 2500 RPM and atrial position, the Q values were 3.4, 6.03 and 8.01 versus 0.77*, 0.43* and 0.58* l/min: p<0.05* for wall-less and the Biomedicus® cannula, respectively. The corresponding pressure values were -15.18, -31.62 and -74.53 versus -46.0*, -119.94* and -228.13* mmHg. At the hepatic position, the Q values were 3.34, 6.67 and 9.26 versus 2.3*, 0.42* and 0.18* l/min; and the pressure values were -10.32, -20.25 and -42.83 versus -23.35*, -119.09* and -239.38* mmHg. At the renal position, the Q values were 3.43, 6.56 and 8.64 versus 2.48*, 0.41* and 0.22* l/min and the pressure values were -9.64, -20.98 and -63.41 versus -20.87 -127.68* and -239* mmHg, respectively.

At the iliac position, the Q values were 3.43, 6.01 and 9.25 versus 1.62*, 0.55* and 0.58* l/min; the pressure values were -9.36, -33.57 and -44.18 versus -30.6*, -120.27* and -228* mmHg, respectivly. Our experimental evaluation demonstrates that the redesigned, virtually wall-less cannulas, allowing for direct venous drainage at practically all intra-venous orifices, outperform the commercially available control cannula, with superior flow at reduced suction levels for all scenarios tested.

An In Vitro and In Vivo Study of the Detection and Reversal of Venous Collapse During Extracorporeal Life Support

The objective of this study was to investigate venous collapse (VC) related to venous drainage during the use of an extracorporeal life support circuit. A mock circulation was built containing a centrifugal pump and a collapsible vena cava model to simulate VC under controlled conditions. Animal experiments were performed for in vivo verification. Changing pump speed had a different impact on flow during a collapsed and a distended caval vein in both models. Flow measurement in combination with pump speed interventions allows for the detection and quantitative assessment of the degree of VC. Additionally, it was verified that a quick reversal of a VC situation could be achieved by a two-step pump speed intervention, which also proved to be more effective than a straightforward decrease in pump speed.

Anesthetic implications for lung transplantation

Anesthetic challenges regarding lung transplantation are related to the expanded spectrum of diseases for which lung transplantation is offered and to the interval changes in health status likely to occur as patients wait longer for an organ to become available. Particular attention to avoiding or reducing the impact of increases in pulmonary vascular resistance and right heart failure are important and may necessitate cardiopulmonary bypass. Intraoperative and postoperative ventilator management should account for differences in pulmonary compliance after the new lung is implanted. Minimizing intravenous fluids without compromising end organ perfusion may avoid or reduce postoperative respiratory insufficiency.

Artificial lungs: a new inspiration

An estimated 16 million Americans are afflicted with some degree of chronic obstructive pulmonary disease (COPD), accounting for 100,000 deaths per year. The only current treatment for chronic irreversible pulmonary failure is lung transplantation. Since the widespread success of single and double lung transplantation in the early 1990s, demand for donor lungs has steadily outgrown the supply. Unlike dialysis, which functions as a bridge to renal transplantation, or a ventricular assist device (VAD), which serves as a bridge to cardiac transplantation, no suitable bridge to lung transplantation exists. The current methods for supporting patients with lung disease, however, are not adequate or efficient enough to act as a bridge to transplantation. Although occasionally successful as a bridge to transplant, ECMO requires multiple transfusions and is complex, labor-intensive, time-limited, costly, non-ambulatory and prone to infection. Intravenacaval devices, such as the intravascular oxygenator (IVOX) and the intravenous membrane oxygenator (IMO), are surface area limited and currently provide inadequate gas exchange to function as a bridge-to-recovery or transplant. A successful artificial lung could realize a substantial clinical impact as a bridge to lung transplantation, a support device immediately post-lung transplant, and as rescue and/or supplement to mechanical ventilation during the treatment of severe respiratory failure.

Extracorporeal membrane oxygenation for severe respiratory failure

The use of extracorporeal technology to accomplish gas exchange with or without cardiac support is based on the premise that "lung rest" facilitates repair and avoids the baso- or volutrauma of mechanical ventilator management. Extracorporeal membrane oxygenation (ECMO), a modified form of cardiopulmonary bypass, has been shown to decrease mortality of neonatal, pediatric and adult respiratory failure and is capable of total gas exchange. In neonates, over 20,638 patients have been treated with an overall survival of 77% in a population thought to have 78% mortality.

Heart transplantation: a thirty-year perspective

Heart transplantation has evolved over the past 30 years into a mainstay of therapy for heart failure patients. As the surgical technique and basic immunology were defined, heart transplantation became a real therapeutic option. Over the next few decades, thoracic transplant teams at Stanford University and other institutions refined this mode of therapy. This review addresses the history, current surgical technique, recipient and donor selection, postoperative care, immunosuppression, short- and long-term complications, and clinical outcomes associated with this procedure.

Selective use of extracorporeal membrane oxygenation is warranted after lung transplantation

OBJECTIVES

Early allograft dysfunction after lung transplantation ranges from subclinical x-ray abnormalities to pulmonary edema, hypoxemia, hypercarbia, and pulmonary hypertension. Management may include extracorporeal circulation to allow recovery of the acute lung injury. We reviewed our experience with extracorporeal membrane oxygenation after lung transplantation to assess the utility of this therapy.

METHODS

A retrospective chart review was performed. Single or bilateral lung transplantation was performed in 444 adults from July 1988 to July 1998. Twelve (2.7%) patients experienced allograft dysfunction severe enough to require extracorporeal membrane oxygenation after failure of conventional therapy, including sedation, paralysis, and inhaled nitric oxide.

RESULTS

Seven of 12 patients requiring extracorporeal membrane oxygenation were discharged from the hospital. Mean and median times to extracorporeal membrane oxygenation support were 1.2 days and 0 days, respectively. Mean length of support was 4.2 days. Four patients died while receiving extracorporeal membrane oxygenation support. One patient was weaned from extracorporeal membrane oxygenation but died during the hospitalization. Two patients required acute retransplantation while receiving extracorporeal membrane oxygenation, and one survived to discharge. Three patients continued to receive extracorporeal membrane oxygenation support for more than 4 days, and all 3 died. All survivors had begun receiving extracorporeal membrane oxygenation support by post-transplantation day 1. Three of 7 patients discharged from the hospital died 12 months, 13 months, and 72 months after transplantation because of bronchiolitis obliterans syndrome (n = 2) or lymphoma (n = 1). Four patients are alive 2, 12, 25, and 54 months after transplantation.

CONCLUSIONS

Extracorporeal membrane oxygenation provides effective therapy for acute post-transplantation lung dysfunction. The frequency and pattern of our extracorporeal membrane oxygenation use reflects bias toward early extracorporeal membrane oxygenation support for isolated graft failure in otherwise intact and uninfected recipients.

Temporary ECMO support following lung and heart-lung transplantation

7 days) failure. Seven (78%) patients in the early group were weaned off ECMO and 5 (56%) survived to hospital discharge. In the late group, none of the patients could be weaned off ECMO, yielding 100% mortality. ECMO support instituted for pulmonary graft failure that occurred within 24 hours of transplantation may improve patient survival.

Antisense intercellular adhesion molecule-1 (ICAM-1) oligodeoxyribonucleotide delivered during organ preservation inhibits posttransplant ICAM-1 expression and reduces primary lung isograft failure

Transiently increased expression of leukocyte adhesion receptors after lung preservation contributes to early graft demise by recruiting leukocytes, activating complement, and causing microcirculatory stasis. We hypothesized that inhibiting intercellular adhesion molecule-1 (ICAM-1) expression even briefly may significantly improve lung graft function and that the preservation period might provide a unique window to deliver a therapeutic pulse of antisense oligonucleotide ICAM-1 to inhibit ICAM-1 expression after transplantation. Interleukin-1beta-treated rat pulmonary endothelial cells given a 20-mer phosphorothioate oligonucleotide comprising an antisense span targeted to the 3'-untranslated region of rat ICAM-1 demonstrated an oligonucleotide dose-dependent reduction in ICAM-1 expression. Using a cationic liposomal carrier, this same antisense oligonucleotide (but not the sense control) instilled into the pulmonary vasculature at the time of preservation reduced subsequent graft ICAM-1 expression and graft leukostasis and markedly improved oxygenation, pulmonary blood flow, and graft survival. These experiments demonstrate that the preservation period presents a window during which to target an anti-ICAM-1 expression strategy to inhibit early adhesion receptor expression and improve functional outcome after lung transplantation.

Development of an ultracompact integrated heart-lung assist device

A novel integrated heart-lung assist device has been developed as a simple to use portable cardiopulmonary support system. The device comprises a centrifugal pump and an artificial lung, which is located around the pump, in an all in one system. The special membrane employed precludes plasma breakthrough in protracted use and enables preprimed setup. Test lungs consisting of the same membrane preserved gas exchange function well after 3 months of preprimed storage. The entire blood contacting surface is treated with covalent heparin bonding to impart good antithrombogenicity. Heparin bonded test lungs could be continuously perfused without systemic anticoagulation as long as 36 days in a venoarterial bypass chronic animal study using goats. The prototype device (diameter, 126 mm; height, 59 mm; membrane area, 0.85 m2; priming volume, 180 ml) demonstrated 9 L/min pump output at a 400 mm Hg pressure head and 180 ml/min oxygen and 110 ml/min carbon dioxide transfer rates at 5 L/min blood flow. We conclude that this device has potential to be the next generation cardiopulmonary support system.

Cardiovascular effects of induced hypothermia after lung transplantation

BACKGROUND

Induced hypothermia may be used to reduce metabolism in acute respiratory failure. Hypothermia is accompanied by an increase in pulmonary vascular resistance, as also seen in the early period after lung transplantation. It was our concern that the combination of the two would lead to an increased workload on the right ventricle.

METHODS

To test this hypothesis we induced hypothermia to 32 degrees C in two groups of pigs. In one group we performed left single-lung transplantation combined with right pulmectomy (TRANSP group); in the other group, only right pulmectomy was performed (PULMEC group).

RESULTS

During hypothermia, there was a significant increase in both groups in pulmonary vascular resistance (TRANSP group, 77%, p<0.05; PULMEC group, 54%, p<0.05) and a significant decrease in cardiac output (TRANSP group, 41%, p<0.05; PULMEC group, 34% p<0.05). Mean pulmonary artery pressure was unchanged, and the work done by the right ventricle was reduced (TRANSP group, 39%, p<0.05; PULMEC group, 31%).

CONCLUSIONS

Induced hypothermia to 32 degrees C after lung transplantation resulted in a significant decrease in the work done by the right ventricle despite a significant increase in pulmonary vascular resistance.

Extracorporeal right to left atrial bypass to treat right ventricular failure

Graft right ventricular failure after heart transplantation, secondary to preoperative functional pulmonary hypertension, was successfully managed in a 49-year-old patient using an extracorporeal right to left atrial bypass. We comment on the case and discuss the type of mechanical assistance used.

New directions in perioperative management for pediatric solid organ transplantation

Advances in pediatric solid organ transplantation have furthered the understanding of end-organ failures and refined the strategies for perioperative management of these otherwise lethal diseases. As the donor pool expands, the number of transplantations increases and long-term survival continues to improve, more complete knowledge of the immunologic and pathologic processes will be gained. A thorough understanding of the principles of transplantation medicine remains essential for physicians to provide optimal perioperative care of pediatric organ transplant patients.

Primary graft failure following lung transplantation

STUDY OBJECTIVES

To determine the incidence of primary graft failure (PGF) following lung transplantation, assess possible risk factors, and characterize its effect on outcomes.

METHODS

Retrospective review of 100 consecutive patients undergoing lung transplantation at the University of Pennsylvania Medical Center. Fifteen patients meeting diagnostic criteria for PGF (PGF+ group) were compared with 85 patients without this complication (PGF- group).

RESULTS

The incidence of PGF was 15%. There was no significant difference in age, sex, underlying pulmonary disease, preoperative pulmonary artery systolic pressure, type of transplant, allograft ischemic times, use of cardiopulmonary bypass, or use of postoperative prostaglandin E1 infusion between the PGF+ and PGF- groups. Induction therapy with antilymphocyte globulin was used less frequently in the PGF+ group (p<0.005). Duration of mechanical ventilatory support was 36+/-43 days vs 4+/-6 days for the PGF+ and PGF- groups, respectively (p<0.0001). Hospital stay was significantly longer in the PGF+ group, averaging 75+/-105 days, compared with 27+/-38 days in the PGF group (p<0.005). One-year actuarial survival for the PGF+ group was only 40% compared with 69% for the PGF- group (p<0.005). Five of the six PGF+ survivors were ambulatory by 1 year; three were completely independent while two continued to require assistance with activities of daily living. Six-minute walk test distance among the ambulatory patients averaged 883+/-463 feet (range, 200 to 1,223 feet) compared with 1513+/-424 feet for the PGF- group (p<0.005). Among the subset of survivors who underwent single lung transplantation for COPD, the mean percent predicted FEV1 at 1 year was 43% for the PGF+ group and 55% for the PGF- groups, but this difference was not statistically significant.

CONCLUSIONS

PGF is a devastating postoperative complication, occurring in 15% of patients in the current series, and it is associated with a high mortality rate, lengthy hospitalization, and protracted and often compromised recovery among survivors.

Induced hypothermia in critical respiratory failure after lung transplantation

Primary graft failure after lung transplantation is a serious complication with high mortality. We present 2 cases of critical respiratory failure after lung transplantation treated with surface cooling to 32 degrees and 35 degrees C, respectively, as an adjunct to conventional intensive care. Both patients were discharged from the hospital in good clinical condition. Surface cooling may be an effective mode of treatment in patients with critical respiratory failure after lung transplantation and should be considered before extracorporeal membrane oxygenation treatment is initiated.

Perioperative management in lung transplantation

Despite the multitude of potential complications that may be encountered during the early post-transplant period, the majority of transplant recipients experience a smooth transition from postoperative intensive care, to step-down unit, to the regular medical floor, and, ultimately, to their home within 10 to 14 days without any significant unexpected events. The likelihood of serious complications can be greatly reduced through careful recipient selection, impeccable donor management, and the cooperative efforts of surgeons, pulmonologists, nurse specialists, and the numerous experienced consultants required for a successful transplant program. Although many unique facets contribute to the complexity of lung transplant patient care, attention to the details of high-quality general postsurgical care will yield excellent results.

ECMO and inhaled nitric oxide for cardiopulmonary failure after heart retransplantation

Cardiopulmonary failure occurred in a 62-year-old patient a few hours after emergency cardiac retransplantation. Venoarterial extracorporeal membrane oxygenation was required to support biventricular dysfunction; thereafter, inhaled nitric oxide was given for residual hypoxemia and pulmonary hypertension. We report survival after venoarterial extracorporeal membrane oxygenation and inhaled nitric oxide treatment for both heart and lung failure in a heart recipient.

Failure to express the P-selectin gene or P-selectin blockade confers early pulmonary protection after lung ischemia or transplantation

Endothelial P-selectin expression contributes to the first wave of neutrophil (polymorphonuclear leukocyte: PMN) influx in several inflammatory conditions. Although remote tissue ischemia, such as a crush injury to the hindlimb, may result in P-selectin-mediated pulmonary leukosequestration, it is not known whether the lungs exhibit a similar response after hypothermic preservation or when subjected to a direct ischemic insult. To determine if P-selectin may mediate early primary graft failure, left lungs harvested from male Lewis rats were preserved for 6 hr at 4 degrees C and transplanted orthotopically into isogeneic recipients. Recipients immunodepleted of PMNs before transplantation demonstrated improved graft function; pulmonary vascular resistance was reduced approximately 6-fold, arterial oxygenation was increased approximately 3-fold, and recipient survival was increased approximately 4-fold (P < 0.05, 0.05, and 0.005, respectively). Administration of a blocking anti-P-selectin IgG 10 min before reperfusion diminished graft PMN infiltration and resulted in improved graft function and recipient survival compared with controls. To establish the role of P-selectin in normothermic pulmonary ischemia, mice were subjected to temporary left pulmonary artery ligation. After functional removal of the nonischemic right lung, mice deletionally mutant for the P-selectin gene (P-selectin-/-) exhibited reduced PMN infiltration (approximately 2-fold), improved arterial oxygenation (approximately 2-fold), and improved survival (approximately 3-fold) compared with P-selectin +/+ control mice (P < 0.05, 0.01, and 0.05, respectively). These studies isolate and identify the central role of a single gene product (P-selectin) in early PMN recruitment and tissue injury after frank pulmonary ischemia and in the setting of lung transplantation after hypothermic preservation.

Extracorporeal membrane oxygenation for lung transplant recipients with primary severe donor lung dysfunction

Primary severe donor lung dysfunction (DLD) is a significant complication after lung transplantation (LTx), and a high mortality is reported with conventional therapy. The purpose of this report is to review the experience of the University of Pittsburgh with extracorporeal membrane oxygenation (ECMO) for primary severe DLD after LTx. From September 1991 to May 1995, 220 LTx were performed at our center. Eight patients (8/220 = 3.6%) with severe DLD after LTx required ECMO support. The age of LTx recipients was 44 +/- 5 years (mean +/- SD); seven patients were female and one was male. Indications for LTx were: chronic obstructive pulmonary disease in four patients, bronchiectasis in two, and pulmonary hypertension in two. There were three single LTx and five bilateral LTx. The interval from LTx to institution of ECMO was 5.6 +/- 3.2 h (range 0-10 h). Three patients were supported with veno-venous (v-v) ECMO and five had veno-arterial (v-a) ECMO. The duration of ECMO support was 7.3 +/- 4.8 days (range 3-15 days). activated glotting time (ACT) was maintained between 110 and 180 s with intermittent use of heparin. Seven patients (7/8 = 87%) were successfully weaned from ECMO and six patients (6/8 = 75%) were discharged home; they are currently alive after a follow-up of 17 +/- 10.1 months. One patient died on ECMO support for refractory DLD and another died 2 months after ECMO wean from multisystem organ failure. At 6 months follow-up, forced expiratory volume in 1 s (FEV1) is 2.35 +/- 0.91 (75% +/- 17.4% predicted) and mean forced vital capacity (FVC) is 2.53 +/- 0.81 (64% +/- 14% predicted). We conclude that ECMO can be lifesaving when instituted early after primary severe DLD. The v-v ECMO support is preferred when the patient is hemodynamically stable and adequate long-term function of the allograft is anticipated.

Inhaled nitric oxide reduces human lung allograft dysfunction

OBJECTIVE

Early severe graft dysfunction, as manifested by hypoxia and pulmonary hypertension, occurs in 10% to 20% of lung transplant recipients. We retrospectively investigated whether inhaled nitric oxide would reduce human lung allograft dysfunction by comparing postoperative hemodynamic data, gas exchange, and outcome in lung transplant recipients with early graft dysfunction treated with or without nitric oxide.

METHOD

Among 243 adult lung transplant procedures, there were 32 patients (13.2%) in whom immediate severe allograft dysfunction developed (arterial oxygen tension/inspired oxygen concentration ratio <150). Group 1 (n = 17) included patients who underwent transplantation before nitric oxide became available in our center and were treated conventionally. Group 2 (n = 15) included those treated with nitric oxide as soon as severe allograft dysfunction was diagnosed. Duration of nitric oxide therapy (20 to 60 ppm) was 15 to 217 hours (average 84 hours).

RESULTS

In group 2, nitric oxide lowered mean pulmonary artery pressure from 30 +/- 2 to 26 +/- 2 mm Hg (p < 0.05), improved the ratio of arterial oxygen tension to inspired oxygen fraction from 88 +/- 10 to 153 +/- 30 (p < 0.05) within 1 hour, and caused a sustained improvement in these parameters during extended therapy. Mean arterial pressure and cardiac index were unchanged during nitric oxide therapy. Transient methemoglobinemia (>6%) developed in two patients. However, no complications were associated with nitric oxide use. Duration of mechanical ventilation was 17 +/- 5 days in group 1 and 12 +/- 3 days in group 2. Four patients had airway complications in group 1, whereas no airway complication was encountered in group 2. Mortality was 24% (4/17) in group 1 and 7% (1/15) in group 2.

CONCLUSION

Nitric oxide improves oxygenation and decreases pulmonary artery pressure without systemic circulatory effects in patients with severe allograft dysfunction. Furthermore, in these patients, nitric oxide may shorten postoperative mechanical ventilation time and reduce airway complications and mortality.

Extracorporeal membrane oxygenation as an adjunct treatment for primary graft failure in adult lung transplant recipients

Primary graft failure is a catastrophic event in lung transplantation. Failure is characterized by profound abnormalities of gas exchange that are frequently unresponsive to alterations in mechanical ventilation. This condition can be fatal and, if less severe, is usually associated with significant permanent damage to the allograft. We report the use of extracorporeal membrane oxygenation as a means to support lung transplant recipients with severe graft failure. Since 1991, extracorporeal membrane oxygenation has been used on 17 occasions for the temporary support of 16 adult lung transplant recipients. All patients met or exceeded standard National Institutes of Health guidelines for institution of extracorporeal membrane oxygenation. Nine double lung, six single lung, and one heart-lung recipients were supported for 1 to 12 days (mean 4.6 +/- 2.2 days). Extracorporeal membrane oxygenation was instituted early, within 7 days of transplantation, in ten patients. Eight early patients (80%) were successfully weaned from extracorporeal membrane oxygenation. Seven of ten (70%) patients were long-term survivors, and five of the seven had normal lung function. In comparison, there were no survivors among six recipients placed on extracorporeal membrane oxygenation for late (> or = 7 days) graft dysfunction. Extracorporeal membrane oxygenation is a lifesaving adjunct in recipients with acute graft failure after lung transplantation. Ischemia-reperfusion injury and acute graft dysfunction after lung transplantation can be successfully reversed with early aggressive intervention.