[Respiratory function in cardiopulmonary transplantation].

Today heart-lung transplantation (HLT) probably provides the best means of studying the role of pulmonary innervation in human respiratory physiology. Outside the periods of postoperative complications ventilatory function, blood gases and exercise tolerance of HLT recipients are compatible with a normal sedentary life. Control of breathing in the waking state at rest, and when asleep, in HLT subject is not different from that of the healthy subject, which suggests that the pulmonary afferents play a negligible role in the control of breathing of adult humans at rest. The results of the ventilatory response to carbon dioxide and to exercise in HLT subjects are contradictory and do not enable any conclusion about the role of pulmonary innervation in these types of integrated responses. On the other hand, the existence of bronchial hyperreactivity to cholinergic stimulation is well established, and is attributed to an upregulation of bronchial muscarinic receptors. An increase in the bronchial response to distilled water observed in some HLT subjects seems on the other and related to episodes of lung rejection. The reflex theory of cough is supported by studies of HLT subjects. Results of studies of the effect of a deep inspiration on bronchomotor tone are far from concordant. Other studies including a large number of subjects and looking at the presence or the absence of reinnervation after transplantation are perhaps two supplementary means to further investigate the respiratory function of HLT patients. Knowledge of the latter would equally enable a better understanding of control mechanisms of human respiratory physiology.