Anaesthetic and perioperative management of lung transplantation

INTRODUCTION

Lung transplantation has been adopted as a therapeutic option for end-stage lung disorders. The pre-operative evaluation should be completed well in advance. The pre-anaesthetic check-up includes routine evaluation and assessment regarding the need for cardiopulmonary bypass during the procedure. Transoesophageal echocardiography (TEE) monitoring is necessary for the assessment of vascular anastomoses.[1,2]. This report describes the perioperative anaesthetic management of two adult patients who underwent successful single-lung transplantation at our institution.

CASE REPORT

The first patient was a 60-year-old male who presented at our institution with complaints of exertional dyspnoea and angina. He was a known case of interstitial lung disease and was dependant on continuous oxygen support (5 L/min) for more than 20 h a day, to maintain a saturation of 90%. He was assessed for lung transplant. Cardiac catheterisation study revealed high pulmonary artery (PA) pressures. The pulmonary vascular resistance (PVR) was high (3.7 wood units). The coronary angiogram showed insignificant coronary artery disease. Dobutamine stress echocardiography confirmed good left ventricular function without any ischaemia. A High-resolution computed tomography scan of the lungs revealed bilateral interlobular interstitial thickening with honeycombing pattern of bronchiectasis and mediastinal lymphadenopathy. Lung perfusion scan revealed relatively reduced perfusion in the left lung contributing to 30% of the total pulmonary function. Pulmonary function tests revealed a significant restrictive pathology with a forced expiratory volume in 1 s of 1.26 L (27% of predicted). He underwent right single-lung transplantation under cardiopulmonary bypass. In view of high PA pressures, cardiopulmonary bypass was initiated after heparinisation with an arterial cannula in aorta and direct right atrial cannulation for venous access. He had a total bypass time of 198 min and total ischaemic time of the graft was 180 min. He was shifted to Intensive Care Unit (ICU) with stable haemodynamics and minimal ionotropic support. He was extubated on the same day of surgery and had an uneventful post-operative period. The post-operative bronchoscopy showed healthy bronchial stump. The patient was provided with regular respiratory care and was shifted to the ward on the 3^rd post-operative day. His endotracheal secretions showed heavy growth of pseudomonas and the growth was adequately managed with injection piperacillin–tazobactam. He recovered well with a smooth post-operative course and was discharged on the 17^th post-operative day with an improved saturation of 98%, requiring minimal support of O₂.

The second patient was a 58-year-old female, who was diagnosed as a case of idiopathic pulmonary fibrosis and suspected Sjogren's syndrome, and was referred to our institution for lung transplant. She was on continuous O₂ support of 10 L O₂/min, maintaining a saturation of 92%. Chest X-ray showed bilateral reticulonodular shadows. The cardiac catheterisation study was indicative of moderate pulmonary arterial hypertension and normal coronary arteries. Pulmonary function tests were suggestive of restrictive lung disease. She underwent right single-lung transplant with an ischaemic time of 261 min. She was shifted to ICU with stable haemodynamics and requiring minimal ionotropic support. Bronchoscopy was done post-operatively which revealed healthy right main bronchial stump. She was extubated on the 1^st post-operative day. She was given immunosuppressive therapy as per our institution protocol.

The selection of both the recipients was based on the guidelines outlined by the International Society for Heart and Lung Transplantation.[3] Both the donor lungs were harvested as part of a multi-organ procurement through a median sternotomy. The donor was heparinised with a dose of 3mg/kg followed by infusion of injection prostaglandin E1 solution into the main PA over 5 min just before the donor inflow occlusion. The antegrade infusion of cold (4°C) Custodiol Histidine-tryptophan-ketoglutarate (HTK) solution (30 ml/kg) was administered into the PA which was vented out through the excised left atrial appendage. After cardiac extraction, the right main bronchus was clamped with the lungs at functional residual capacity. The factors important for lung preservation are flush cooling (4°C), cold storage and storage in the inflated state with oxygen. We used Custodiol HTK solution for the donor lung preservation. It claims to improve immediate post-transplant lung functions with an enhanced PO₂/FiO₂ ratio. Dextran 40 and low potassium concentration contribute to uniformly excellent lung preservation.[2,3,4]

Routine induction of anaesthesia was carried out with monitoring of ECG, central venous pressures, capnography, arterial pressures, urinary output and core temperature. A Swan-Ganz catheter was inserted to monitor the PA pressures. Intraoperative TEE was used to assess the adequacy of vascular anastomosis and cardiac function in the post-procedure period. Anaesthesia was induced gradually to avoid any sudden decrease in systemic pressure or increase in PVR with intravenous (iv) injection midazolam 0.1 mg/kg and iv injection fentanyl 15 mg/kg. Muscle relaxation was achieved with iv injection pancuronium 0.2 mg/kg. Anaesthesia was maintained with oxygen, air and isoflurane. Post-transplant analgesia was maintained with iv fentanyl. The patient was extubated on the same day in the evening.

The procedure was performed through a right posterolateral thoracotomy approach under left endobronchial intubation. Cardiopulmonary bypass was established after adequate heparinisation, and pneumonectomy was performed. Care was taken to maintain the mean PA pressure not to exceed 20 mmHg for 10 min to facilitate controlled pressure reperfusion conditions. The lung was ventilated on 50%–100% oxygen before the weaning off from cardiopulmonary bypass.

In the second patient, in view of acceptable pulmonary pressures, transplantation was carried out without the usage of cardiopulmonary bypass.

Both patients were administered with injection basiliximab 20 mg intravenous (iv), injection mycophenolate mofetil 1gm iv and injection methyl prednisolone 500 mg iv at the time of induction of anaesthesia, along with the empirical antibiotics. In addition, they were supplemented with valganciclovir, co-trimoxazole and fluconazole. Injection methyl prednisolone was continued, in the immediate post-operative period at a dose of 125 mg for every 8 h. They were supplemented with adequate immunosuppressant therapy as per the protocol. During the post-operative period, regular fibreoptic bronchoscopy with bronchoalveolar lavage (BAL) was performed on post-operative days 1, 2, 4, 6, 9, 12, 15 and 21, in both the patients. The bronchoscopy was performed before 7 am in the morning which helped clear the overnight secretions, avoiding excessive fasting by the patient. BAL is very useful in identifying infectious complications. Serial monitoring of tacrolimus levels and renal parameters were done, and optimal dose of tacrolimus was administered.

DISCUSSION

Both our patients were oxygen dependent with end-stage lung disease. We had performed extensive assessment of the right and left ventricular functions, severity of pulmonary hypertension, exercise tolerance and other system functions. Single-lung ventilation was instituted with continuous monitoring of the oxygenation and haemodynamic variables. Precise positioning of the double-lumen endotracheal tube and confirming with bronchoscopy is mandatory. The first patient had moderate pulmonary arterial hypertension with a higher PVR. de Hoyos et al. reviewed the cardiopulmonary performance during lung transplant and found that with the clamping of PA, cardiac index is reduced by 31% with an increase in the PVR. The increased risk of cardiac instability was predicted in the first patient and elective cardiopulmonary bypass was initiated before the lung explantation.[3,4]

The implanted lung is often prone to the development of low-pressure pulmonary oedema as a result of ischaemia–reperfusion injury. This condition is described as 'pulmonary reimplantation response' manifesting as hypoxaemia and interstitial shadowing in the immediate post-operative period. Longer ventilatory support with higher positive end-expiratory pressure and a low FiO₂, strict fluid restriction and diuretic therapy can be helpful in minimising the alveolar transudation.[3,4,5]

The denervated lung has a decreased ventilatory response to hypercapnia and decreased cough reflex resulting in decreased pulmonary clearance. Serial bronchoscopic procedures were done in this regard to improve the oxygenation and prevent pneumonia. Apart from the protocol-based medication, appropriate antimicrobials were administered based on the culture growth of bronchoalveolar lavages.

CONCLUSION

Fluid management avoiding fluid overload and lung isolation for one-lung ventilation using either double-lumen tube or bronchial blockers are crucial for smooth conduct of lung transplantation procedure. Bronchoscopic study and bronchoalveolar lavage at regular intervals in the early post-operative period help to identify infectious complications. Preoperative evaluation of pulmonary vascular resistance and cardiac function is important to determine the need for cardiopulmonary bypass during the procedure.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.