EFFECT OF LUNG TRANSPLANTATION ON DIAPHRAGMATIC FUNCTION IN PATIENTS WITH CHRONIC OBSTRUCTIVE PULMONARY-DISEASE

Background - To date there are no data on the effects of lung transpla ntation on diaphragmatic function in patients with end stage chronic o bstructive pulmonary disease (COPD). It is not known whether the relat ion between the transdiaphragmatic pressure (PDI) and lung volume is a ltered in recipients after transplantation as a result of changes in d iaphragmatic structure caused by chronic hyperinflation. The effect of lung transplantation on diaphragmatic strength was determined in pati ents with COPD and the relation between postoperative PDI and lung vol ume analysed. Methods - Diaphragmatic strength was assessed in eight d ouble lung transplant recipients, six single lung transplant recipient s, and in 14 patients with COPD whose lung function was similar to tho se of the transplant recipients preoperatively. PDI obtained during un ilateral and bilateral phrenic nerve stimulation at 1 Hz (twitch PDI) at functional residual capacity (FRC) and during maximal sniff manoeuv res (sniff PDI) at various levels of inspiratory vital capacity (VCin) served as parameters for diaphragmatic strength. Sniff PDI assessed a t the various VCin levels were used to analyse the PDI/lung volume rel ation. Results - Lung transplantation caused a reduction in lung volum e, especially in the double lung transplant recipients. As a consequen ce sniff PDI was higher in the double lung transplant recipients than in the patients with COPD at all levels of VCin analysed. However, sni ff PDI values analysed at comparable intrathoracic gas volumes were no t reduced in the patients with COPD when compared with those who under went lung transplantation. Bilateral twitch PDI values were similar in the patients with COPD and in the lung transplant recipients. In the single lung transplant recipients unilateral twitch PDI values were si milar on the transplanted and the non-transplanted side. The relation between PDI and lung volume was similar in the patients with COPD and in the lung transplant recipients. Conclusions - In patients with COPD lung transplantation leads to an increase the maximal sniff induced P DI values by placing the diaphragm in a more favourable position for p ressure generation. Since patients with COPD and postoperative lung tr ansplant recipients showed similar PDI/lung volume relations, this sug gests that chronic pulmonary hyperinflation does not cause major funct ional alterations of the diaphragm.