Donor Lung and Heart-Lung Offer
Many of the factors to consider when a potential lung or heart-lung offer is made are similar to an isolated cardiac transplant - ABO group, size, cause of death, distance from transplant center, immunological compatibility etc. Other aspects differ - recipient factors need to include etiology of lung disease, sizing is more critical and assessing the lung function very important. In the case of heart lung transplants the cardiac function is also important. Recipients are usually older - often teenagers or young adult and so adult guidelines are more applicable. Decisions should therefore always be shared with the team and recorded so the decision can be reviewed retrospective and increase the institutional experience.
These guidelines below are limited by the quality of evidence. Unfortunately the evidence is weak and the majority of statements are based on "expert opinion" or long standing practice
Excellent resources are the “Donor Quality Assessment and size match in Lung Transplantation” Mangukia et al. Indian Journal of Thoracic and Cardiovascular Surgery 2021; 37 (suppl3 ):S401-415, A Review of Lung Transplant Donor Acceptability Criteria. A consensus report from The Pulmonary Council of the International Society. JHLT 2003:22:1183-1200 https://doi.org/10.1016/S1053-2498(03)00096-2 and a special edition of Pediatric Transplantation (Volume 24, Issue 3, May 2020) with an excellent review of donor comorbidity and infections.
ABO matching & HLA Antibodies
ABO Matching: It is critical that the ABO group of the donor is matched to the recipient, otherwise hyperacute rejection will occur in the operating room and be unrecoverable. Acceptable matches are shown in Table 1. Matching of Rhesus type is not necessary. ABO mismatches are possible in exceptional circumstances. See the section in immunology for more details.
HLA Antibodies: Around 10-20% of recipients have preformed HLA antibodies. If the titres are high and depending on the HLA class they may cause hyperacute rejection. Virtual cross matching can now be performed in advance - if the recipient has preformed HLA antibodies they can be assess against the donor HLA type prior to transplant and if a strong reaction is predicted the donor used for a different recipient. More details are in the immunology section
Unlike in heart transplants mismatched lung sizes, even of relatively small degree, cause challenges. Oversized lungs may be difficult of impossible to implant into the thoracic cavity whilst undersized lungs are more prone to pneumothorax and hemothorax. Disparity in bronchial size also leads to technical difficulties at implant and hence potential for dehiscence.
- Height & Gender: For lung transplants, height (along with gender and weight) is the most important factor in deciding the predicted total lung capacity (pTLC). The calculation is from (Kilburn et al. Thorax. 1992; 47: 519–523. doi: 10.1136/thx.47.7.519). Donor:Recipient ratio should parallel D:R pTLC when there the genders are the same. It is generally considered that female lung volumes are 20% less than a height matched male
- CXR Measurements: Measurements are made on both sides form the apex of the lung to the top of the diaphragm and the diameter at the maximum point. Note that the donor measurements are made supine and the recipient usually erect.
- Weight: Weight differences are generally not taken into account but are part of the pTLC calculation
- Age Difference: Adult donors less than 55 years old may be readily utilized and in adults much older donors have been utilized. In children by prioritizing pTLC age difference is not so much an issue as children with a similar pTLC are likely to be of a similar age. However teenager donors are thought to have smaller lungs than their calculated adult equivalents but it is not usually a technical issue as their lungs are more compliant than adults and able to adapt more easily to older chest cavities
- Recipient disease: Pulmonary fibrosis often leads to smaller chest cavities and chest Xray dimensions may be more important than calculated pTLC in size matching
Cause of Death and Resuscitation
- Cause of Death: Traumatic deaths (principally road traffic accidents in Europe) may result in chest trauma and significant lung contusion, pneumothorax and hemothorax. These often resolve with time and drainage and are not usually a containdication to donation.
- Trauma to the head or cerebral vascular accidents (especially intracranial haemorrhage) or coma from drug overdose results in hypoventilation and hypoxia. These patients are prone to vomiting and at risk of aspiration pneumonia.
- Resuscitation: Vigorous resuscitation may result in lung trauma however if the function recovers then it is unlikely to cause problems and a history of CPR should not preclude donation
- Hanging: Lungs from hanging victims are considered marginal as post obstructive barotrauma to the alveolar-capillary bed often results in results in reperfusion injury and pulmonary edema. Despite this studies have not shown any adverse transplant outcomes when these donors are used.
- Drowning: During drowning a voluntary apnea usually occurs until CO2 levels rise sufficiently and triggers involuntary breathing leading to aspiration. A small percentage of victims however remain apneic - "dry drowning". Water temperature is also important as hypothermia may protect the lungs. Drowning is not a contraindication to donation provided the lung function testing is normal.
- Asthma: Donation from status asthmaticus patients is not generally considered as they usually have a high pulmonary artery pressure due to hypercarbia.
Donor Lung Function
The current guidelines, essentially unchanged, are over 30 years old although they were reviewed in 2003 and a consensus report from The Pulmonary Council of the International Society published in JHLT 2003:22:1183-1200 https://doi.org/10.1016/S1053-2498(03)00096-2 the evidence (or rather lack of it) for the recommendations. Accordingly various institutions have modified the criteria to accept extended donor criteria. Table 1 below is a typical example that many institutions would accept. Pediatric studies have also demonstrated good outcomes from extended criteria donors.
The assessment includes the history, CXR, CT scan, bronchoscopy and ventilating in 100% oxygen to assess the PO2/FiO2 ratio (PO2 when the FiO2 is 1- 100% oxygen).
This is really the only donor parameter to be shown to directly relate to outcomes, especially primary graft failure. If possible it should be within 6 hours for lung transplants. However successful outcomes with much longer ischemic times are well recorded.
Transmission of donor infections is well recognized but uncommon (< 1%) due to screening techniques. Conway et al published a comprehensive review of the implications of donor infections.
- Covid-19: There are no significant reports of intentional lung transplants from Covid-19 patients and at this time it is not advisable
- Bacterial Infections: These may be the primary cause of death e.g. meningococcal septicemia or nosocomial acquired. By the time donation is considered usually the bacterium and antibiotic sensitivity has been determined and treatment given. Even if this is not the case, no deaths have ben reported from blood culture positive donors. Although there are no reports in the literature, donors with multi-drug resistant organisms should be used with caution. Tuberculosis has been transmitted in adults but responds to treatment. Lung donation can therefore be accepted in the absence of Xray evidence of pneumonia. Bacterial infections are not a contraindication to donation and transplant can proceed provided the recipient is covered with appropriate antibiotics
- Virology: Nucleic Acid Amplification Testing (NAT) is a quick and reliable method of detecting viruses. There is however a short window between acquiring an infection and a NAT positive test so occasionally despite negative testing, transmission can occur. Infectivologists should be consulted before utilizing donor with Hepatitis B or C. For HBV there is limited data on whether recipient prophylaxis can prevent infection and it is not recommended. For HCV adult recipients, donation is not contraindicated as treatment is effective. In children treatment for HCV is available for those 11 years of age or more and case reports have shown success in utilizing HCV donors. HIV is an absolute contraindication although there are now increasing numbers of HIV positive recipients receiving HIV positive donor organ.
- Smoking: Donation is generally not considered from those who have smoked more than 20 pack-years (1 pack year is equal to smoking 1 pack per day for 1 year). So this is equivalent to a pack a day for 20 years, (or 2 packs a day for 10 years), especially if they are older.
- Vaping: There are currently no reports of patients with a known history of vaping being used as donors, although there are reports of "vapers" requiring lung transplantation.
- Asthma: Asthmatics who are well controlled on treatment are considered a high risk and even those with only a history of asthma are considered medium risk. These recommendations are based on the presumption that pre-existing airway inflammation will predispose to early and late graft dysfunction
- Diabetes: Neither type I or type II diabetes is associated with adverse outcomes, however they may be a risk factor for donor coronary disease
- Anaphylaxis: This is a rare cause of death but while the allergy can be transferred to the recipient it is not a contraindication
- Malignancy: There is very little data on the transmissibility of malignancy and none in pediatric donors. Those donors whose primary malignancy is confined to the cranium can certainly be used. For other malignancies it is reasonable to expect a low risk in those who are cancer free for 5 years with an expectation of a high cure rate. It should be born in mind that some cancer treatments, notably radiotherapy to mediastinum may cause late respiratory dysfunction
- Addiction: Concern has been expressed for donations from drug and or alcohol abuse. There are concerns regarding the lifestyle of addicts and their exposure to viral infections e.g. HIV and Hepatitis. Despite these concerns post transplant outcomes have been demonstrated to be unaffected by donation from addicts
Last Updated: September 2022