Applied physiological principles in the management of a lung allograft to thoracic cavity size mismatch in severe emphysema

Abstract

In this review, we discuss physiological principles that guided the management of a lung transplant for emphysema related to alpha-1-antitrypsin deficiency, where a lung allograft to thoracic cavity size mismatch occurred (donor-to-recipient predicted total lung capacity [pTLC] ratio was 0.89, donor pTLC-to-recipient actual-TLC ratio 0.62). In emphysema, the loss of lung elastic recoil and airway obstruction leads to air trapping and lung hyperinflation. Remodeling of the thoracic cavity (“barrel chest”) develops, which has implications for donor-to-recipient sizing and postoperative management of lung transplantation. We discuss the physiology of a relatively undersized allograft and the impact on chest tube, mechanical ventilation, and respiratory system mechanics management. This case also illustrates how chronic adaptations of the ventilatory pattern to advanced lung diseases are reversible and the chest cavity size can remodel back to normal after lung transplantation.

Keywords

• lung transplant
• emphysema
• collateral ventilation
• size mismatch
• chest tube