After lung transplantation
Recipients, after lung transplantation, are treated with three types of anti-rejection drugs (immunosuppressants). These are: cyclosporine or tacrolimus, azathioprine or mycophenolate, mofetil and prednisolone . In most centers, then, patients receive post-operative prophylaxis against cytomegalovirus (CMV) infection with antiviral drugs.
The follow-up (tight control of the operation) after a lung transplant is extremely complex and requires a high level of patient cooperation. The main objective is to avoid, recognize and treat preventively all complications. Apart from the patient's collaboration, regular examinations, contact with the transplant center, chest x-ray examinations, laboratory tests, pulmonary function tests and bronchoscopy are also essential. In the initial phase, usually, the lung function continuously improves and reaches a plateau (state phase) after about 3 months. Then, the values vary only slightly. A drop in lung function value of more than 10% may be indicative of a serious problem such as rejection, infection, airway obstruction or obstructive bronchiolitic syndrome (BOS). To diagnose an early complication of transplantation, some centers recommend assessing spirometry at home: the patient is discharged in possession of a spirometer released by the hospital, and has the task of checking his own spirometry 2 times a day and contacting the center in case this was abnormal.
Organ dysfunction after transplantation
In the initial phase of lung transplantation, there may be dysfunction of the transplanted organ (marked as PGD), characterized by widespread and visible pulmonary infiltration, but not always, by conventional Computed Tomography and, only if very numerous and serious, on the radiograph of the Chest.
PGD occurs in 11-60% of patients; its development in the first post-operative period would negatively affect their long-term survival. The researchers found that PGD, in its most severe form, exposes patients to a high risk of mortality after transplantation, so the period of intensive therapy and days of post-operative hospitalization must be increased.
For the evaluation, classification and definition of PGD, many scholars have thought they could use a new high resolution Computed Tomography, called HRCT (High Resolution Computer Tomography) or MSCT (Multi-Slice Computer Tomography), which is capable of performing of tomographic scans (ie to scan and represent, thanks to X-rays, extremely thin "slices" of portions of the human body) at high resolution. Its use has been tested and approved in studies on cystic and pulmonary fibrosis, and on chronic obstructive bronchitis with or without pulmonary emphysema, in which it has proved to be an extremely useful tool to characterize the disease.
However, the use of this new machine on PGD has not yet been sufficiently tested to monitor the first, most critical phase after a lung transplant, even if the results seem promising and we think, in the very near future, of being able to use it successfully even in this case. In fact, the abnormalities of the pulmonary structure visible on CT are closely linked to the severity of the disease, and it is therefore recommended, to evaluate PGD, to consider the use of HRCT. The scan plan with HRCT (or MSCT) that is expected to be used, after a transplant, is shown in Table 2 .
It has been shown that, using this technique, even the smallest airways can be optimally visualized, thanks to the machine's ability to produce high resolution scanner overlays, from 0.5 mm to 1-2 mm thick, of the whole chest. The advantages of HRCT are represented by the fact that there are also small details and the ability to distinguish areas of lung parenchyma that show different pathological patterns. A potential disadvantage, however, is the exposure of patients to high doses of radiation.
Table 2 - MSCT scanning plan
First MSCT: Third day post-lung transplantation: major pulmonary changes are expected at this time.
Second MSCT: Fourteenth post-transplant day. Biopsies will be done before the scan to avoid artifacts. Most patients with PGD will have a normal chest x-ray, while with MSCT clear morphological changes in lung tissue can be observed.
Third MSCT: Three months post-transplant: most patients have achieved stable lung function, near the maximum achievable after transplantation. Thus, at this stage, the risk of developing PGD is out of date.
Fourth MSCT: Twelve months post-transplant. Patients will be quite stable so any changes found to the lungs at this time will most likely be chronic.
