Donor prone positioning protects lungs from injury during warm ischemia

The Effect of Prone Positioning After Lung Transplantation

BACKGROUND

Prone positioning has become a standard therapy in acute respiratory distress syndrome to improve oxygenation and decrease mortality. However, little is known about prone positioning in lung transplant recipients. This large, singe-center analysis investigated whether prone positioning improves gas exchange after lung transplantation.

METHODS

Clinical data of 583 patients were analyzed. Prone position was considered in case of impaired gas exchange Pao2/fraction of oxygen in inhaled air (<250), signs of edema after lung transplantation, and/or evidence of reperfusion injury. Patients with hemodynamic instability or active bleeding were not proned. Impact of prone positioning (n = 165) on gas exchange, early outcome and survival were determined and compared with patients in supine positioning (n = 418).

RESULTS

Patients in prone position were younger, more likely to have interstitial lung disease, and had a higher lung allocation score. Patients were proned for a median of 19 hours (interquartile range,15-26) hours). They had significantly lower Pao2/fraction of oxygen in inhaled air (227 ± 96 vs 303 ± 127 mm Hg, P = .004), and lower lung compliance (24.8 ± 9.1 mL/mbar vs 29.8 ± 9.7 mL/mbar, P < .001) immediately after lung transplantation. Both values significantly improved after prone positioning for 24 hours (Pao2/fraction of oxygen ratio: 331 ± 91 mm Hg; lung compliance: 31.7 ± 20.2 mL/mbar). Survival at 90 days was similar between the 2 groups (93% vs 96%, P = .105).

CONCLUSIONS

Prone positioning led to a significant improvement in lung compliance and oxygenation after lung transplantation. Prospective studies are needed to confirm the benefit of prone positioning in lung transplantation.

Ventilation in the prone position improves oxygenation and results in more lungs being transplanted from organ donors with hypoxemia and atelectasis

BACKGROUND

Hypoxemia is the most common barrier to lungs being transplanted from eligible organ donors who are brain dead (BD). Atelectasis is the principal reversible contributing factor to hypoxemia after brain death. We evaluated prospectively whether ventilation in the prone position in donors who are BD would reverse atelectasis, improve oxygenation, and result in more lungs being transplanted.

METHODS

Organ donors managed at the recovery center of 1 organ procurement organization over a 2-year period who exhibited hypoxemia (partial pressure of arterial oxygen [PaO₂]/fraction of inspired oxygen of <300 mm Hg) and had evidence of atelectasis were ventilated in the prone position for 12 hours or longer during donor management. A subset underwent computed tomography (CT) imaging to quantify the degree of atelectasis before and after prone positioning. Outcomes were compared with those of a control group with hypoxemia and atelectasis managed similarly but in the supine position in the previous 2 years.

RESULTS

A total of 40 lung-eligible donors who were BD with hypoxemia and atelectasis were managed in a prone position and compared with 79 donors in supine position. Baseline PaO₂ was similar between the prone and the supine groups (194 ± 78 vs 177 ± 77 mm Hg, p = 0.26) but increased more in the prone group at 4 hours (by 113 vs 54 mm Hg, p = 0.001) and remained 74-mm Hg higher at 12 hours (340 vs 266 mm Hg, p = 0.0006). CT-graded atelectasis was significantly reduced after ventilation in the prone position but persisted in the supine group (p = 0.001). Final PaO₂ was not significantly higher (344 vs 306, p = 0.12), but lungs were more often transplanted in the prone group (45% vs 24%, p = 0.03).

CONCLUSIONS

Ventilation in the prone position reverses atelectasis and rapidly and sustainably improves oxygenation in organ donors who are BD with hypoxemia. This effect appears to translate into more lungs being transplanted.

Initial lung transplantation experience with uncontrolled donation after cardiac death in North America

Uncontrolled donation after cardiac death (uDCD) has the potential to ameliorate the shortage of suitable lungs for transplant. To date, no lung transplant data from these donors are available from North America. We describe the successful use of these donors using a simple method of in situ lung inflation so that the organ can be protected from warm ischemic injury. Forty-four potential donors were approached, and family consent was obtained in 30 cases (68%). Of these, the lung transplant team evaluated 16 uDCDs on site, and 14 were considered for transplant pending ex vivo lung perfusion assessment. Five lungs were ultimately used for transplant (16.7% use rate from consented donors). The mean warm ischemic time was 2.8 hours. No primary graft dysfunction grade 3 was observed at 24, 48, or 72 hours after transplant. Median intensive care unit stay was 5 days (range: 2-78 days), and median hospital stay was 17 days (range: 8-100 days). The 30-day mortality was 0%. Four of 5 patients are alive at a median of 651 days (range: 121-1254 days) with preserved lung function. This study demonstrates the proof of concept and the potential for uDCD lung donation using a simple donor intervention.

The unique moral permissibility of uncontrolled lung donation after circulatory death

Implementing uncontrolled donation after circulatory determination of death (uDCDD) in the United States could markedly improve supply of donor lungs for patients in need of transplants. Evidence from US pilot programs suggests families support uDCDD, but only if they are asked permission for using invasive organ preservation procedures prior to initiation. However, non-invasive strategies that confine oxygenation to lungs may be applicable to the overwhelming majority of potential uDCDD donors that have airway devices in place as part of standard resuscitation. We propose an ethical framework for lung uDCDD by: (a) initiating post mortem preservation without requiring prior permission to protect the opportunity for donation until an authorized party can be found; (b) using non-invasive strategies that confine oxygenation to lungs; and (c) maintaining strict separation between the healthcare team and the organ preservation team. Attempting uDCDD in this way has great potential to obtain more transplantable lungs while respecting donor autonomy and family wishes, securing public support, and enabling authorized persons to affirm or cease preservation decisions without requiring evidence of prior organ donation intent. It ensures prioritization of life-saving, the opportunity to allow willing donors to donate, and respect for bodily integrity while adhering to current ethical norms.