Successful management of donor-acquired fat embolism after lung transplantation

Abstract

Fat embolism is a serious complication in patients with multiple traumatic injuries. It is often asymptomatic during the first hours of resuscitation, thus remains underdiagnosed in patients who progress to brain death. Lung transplantation issued from such grafts can lead to severe lung primary graft dysfunction, the management of which is deemed difficult. Herein, we report a successful management of donor-acquired fat embolism syndrome after lung transplant in a 22 years old woman for cystic fibrosis. Fat embolism was suspected because of the donor’s traumatic injuries and confirmed by histopathological analysis. An immediate postoperative primary graft dysfunction was successfully managed with veno-arterial extracorporeal membrane oxygenation. The patient is alive 31 months after surgery.

CASE REPORT

We report the case of a 22-year-old female patient who underwent bilateral sequential lung transplantation (LT) for cystic fibrosis in December 2017.

Lung grafts were procured from a 27-year-old male with brain death after a motor vehicle accident. His injuries involved the head and the extremities (Fig. 1a and b), sparing the chest (Fig. 1c). His PaO₂/FiO₂ ratio was 482. Oto lung donor score was 0. Fat embolism was not suspected and axillary or sub-conjunctival petechiae have not been searched.

Figure 1:

(A) Right diaphyseal femoral fracture, (B) right tibial and fibular fractures, (C) donor’s chest computed tomography scan.

There was a slight size-mismatch between the donor and recipient necessitating bilateral wedge resections in the right middle lobe, and lingula.

Initially, the transplantation was technically successful with no need for extra-corporal circulatory assistance. However, this was complicated with severe pulmonary oedema upon reperfusion of the second allograft (Fig. 2a). The patient developed severe hypoxia with PaO₂/FiO₂ of 70 mmHg. Haemodynamically, early vasoplegia necessitating vascular filling was noted. There was no evidence of right or left heart failure in transoesophageal echocardiography, and a discrete increase in pulmonary arterial pressure was seen on swan-ganz catheter (mean PAP: 36 mmHg).

Figure 2:

(A) Postoperative chest X-ray, (B) chest X-ray at discharge, (C) histopathological analysis of right middle lobe volume-reduction wedge 120 min after first graft reperfusion: embolic occlusion of pulmonary arterioles by adipose cell islands and haematopoietic bone marrow cells.

A femoro—femoral veno-arterial extracorporeal membrane oxygenation (ECMO) (25–15 Fr) was surgically inserted through a right groyne approach with distal limb reperfusion. This was kept for a total of 5 days.

ECMO blood flow was regulated to maintain SaO₂ > 90%, ETCO₂ > 15 and a pulsatile pressure in pulmonary artery on swan-ganz catheter. A protective ventilation was instituted with low volume (Vt = 5 ml/kg), high PEEP (12–16 cmH₂O) to keep plateau pressure <28 cmH₂O. The patient was anticoagulated using non-fractionated heparin with a plasma anti-Xa assay between 0.2 and 0.4 ui/ml.

The diagnosis of donor-acquired fat embolism syndrome (DAFES) was sought out on the basis of the donor’s history and was confirmed by histopathological analysis of the volume-reduction wedges. This showed occlusion of pulmonary arterioles by adipose cell islands and haematopoietic bone marrow cells; both suggestive of fat embolism (Fig. 2c).

Her postoperative course involved extubation at Day 9 and stepping down from intensive care unit at Day 11. She was discharged home at Day 31 (Fig. 2b).

Despite FE being treated successfully and the patient surviving till now, 31 months after the surgery, she unfortunately developed successive rejections 5 months postoperatively. Severe bronchiolitis obliterans syndrome was diagnosed and she is currently under evaluation for retransplantation.

DISCUSSION

The diagnosis of DAFES as a cause of early primary graft dysfunction can be quite difficult, with limited therapeutic options, and high mortality rates.

Literature review revealed 7 cases of DAFES, of these 4 were single and 3 were bilateral LT [1].

Among the reported cases of DAFES in bilateral LT, only 2 were discharged alive [2, 3], one of these had postoperative veno-venous ECMO. None of the cases benefited from circulatory assistance in the deceased group.

There is another case of DAFES in single LT who survived without assistance, probably due to the native contralateral lung [1].

It is important to take into consideration, during harvesting, the presence of fat droplets in the reperfusion fluid. This sign was described by only one case in the literature [4].

As a matter of fact, our institutional protocol consists of anterograde and retrograde pneumoplegia, and during the postoperative debriefing of the case, the harvesting surgeon recalled seeing fat droplets during retrograde flushing. Since then, we started naming it the sign of ‘Pot au feu’, as it reminds us of the fat droplets we notice when cooking this classical French dish (Supplementary Material, Figure).

Although, the use of veno-venous or veno-arterial ECMO for primary graft dysfunction is still debated. In our practice, veno-arterial ECMO remains the first-line treatment of severe primary graft dysfunction during first 72 h, as it decreases lung capillary blood flow, provides haemodynamic support and enhances oxygenation [5].

While the pathophysiology of FE remains unclear [3], we would like to point out that all the reported cases who initially survived DAFES (including this one), developed chronic lung allograft dysfunction. The other 2 cases died of this at 19 and 26 months after LT. More retrospective analysis should be performed in order to explore the possible role of FE as a risk factor for early rejection.

Since Steen and colleagues [2], published their case series of transplanted initially rejected lung after ex vivo lung perfusion, this technique became well established in testing and reconditioning marginal lungs. In case of suspicious of FE, it could have a role to reassess and optimize grafts. It will also give us time to analyse the bronchioalveolar lavage of the donor’s lung, as the absence of fat globules has a highly predictive negative value of FE [3].

In conclusion, transplant surgeons should take extra precautions when noticing the sign of ‘pot au feu’ during retrograde pneumoplegia. A negative bronchioalveolar lavage, and a successful ex vivo lung perfusion would be encouraging to perform LT.

SUPPLEMENTARY MATERIAL

Supplementary material is available at ICVTS online.

Reviewer information

Interactive CardioVascular and Thoracic Surgery thanks the anonymous reviewer(s) for their contribution to the peer review process of this article.