Allan R Glanville, MBBS; Genevieve ...

Allan R Glanville, MBBS; Genevieve M Gabb, MBBS; James Theodore, MD F.C.C.P.;([unkeyable]) and Eugene D Robin, M.D.([unkeyable])

Heart-lung transplant (HLT) recipients characteristically display marked bronchial hyperresponsiveness (BHR) to inhaled methacholine, if it be not that their bronchial responsiveness (BR) to exercise has not been reported. We measured BR to exercise in 13 stable HLT recipients, 13 normal command (NC) subjects and 13 asthmatic patients (AS). All exposes exercised for eight minutes forward a bicycle ergometer at a work flat designed to obtain and maintain 80 percent maximum heart rate, or to tolerance. The postexercise fall in [FEVsub1] was equivalent in the HLT clump and the NC group (0[+ or -]02 L v 0[+ or -]02 L:p=NS) in contrast to the AS collection (-0.6[+ or -]0.5 L:p<0.01). Stable HLT recipients do not exhibit BHR to exercise at tolerable work loads. This observation supports the hypothesis that BHR to methacholine after HLT is owing to denervation hypersensitivity of muscarinic receptors rather than other causes.

It has been demonstrated previously that stable HLT recipients display marked BHR to inhaled methacholine,[1] possibly owing to denervation hypersensitivity of muscarinic receptors deprived of tonic vagal stimulation. Despite this, HLT recipients are capable of sustaining vigorous exercise without ventilatory limitation[2] and characteristically do not complain of exercise-induced dyspnea and wheeze. Whether significant exercise-induced airflow limitation come abouts in this group has not been criterioned formally.

In asthmatic enthralls the precise pathophysiologic mechanism[3] of exercise-induced airflow limitation is unknown. In particular, the putative part of neural reflexes remains unsubstantiated. The finding of exercise-induced airflow limitation in HLT recipients would argue violently for the importance of local mediators of bronchoconstriction and against a part for a reflex neural component

In this close attention we report for the first time a systematic examination of the time course and magnitude of changes in airflow induced from exercise in stable HLT recipients, comparing it with observations in normal and asthmatic subjects

METHODS

Patient Population

The patient cogitation group was comprised of 13 stable HLT recipients aged 33[+ or -]9 years (mean [+ or -] SD) (range 15 to 42 years) who were evaluated 164[+ or -]177 month station HLT (range one to 51 months) which had been performed for irreversible pulmonary hypertension appropriate to primary pulmonary hypertension (PPH) (n=4) or becoming to congenital heart disease with Eisenmenger's syndrome (ES) (n=9) Individual patient details are provided in Table 1 At the time of the investigation no patient had had evidence of respiratory tract infection in the previous four weeks. All patients were taking a standard maintenance immunosuppressive regimen which was comprised of cyclosporine A (to maintain a depression serum level of 75 to 100 ng/ml at radioimmunoassay), azathioprine (1 to 15 mg/kg depending forward leukocyte count), and prednisolone (02 mg/kg) Patients 1 and 6 (Table 1) had stable airflow limitation in keeping with obliterative bronchiolitis[4] moreover histologic confirmation had not been obtained at the time of this study

pair control groups ([normal subjects [n=13] and asthmatic make liables [n=13]) were recruited from the staff of the medical center For the purports of this study, normal and asthmatic subdues were defined under the criteria of the American Thoracic Society.[5] Asthmatic controls were chosen irrespective of the demeanor or absence of exercise-induced symptoms. At the time of the cogitation none of the asthmatic patients had had a chaste exacerbation of symptoms in the preceding month and none was taking regular bronchodilator therapy. Each enthrall gave informed consent to the research which was performed under the guidelines of the Stanford University Medical Center Committee for the Protection of Human make submissives in Research.

Protocol

Each expose performed an identical protocol. Prior to subject of attention subjects were advised to avoid all bronchodilators for a period of at least 12 hours, including dietary sources of methylxanthines, and to avoid vigorous or sustained exercise forward the morning of the studious mood Exercise studies were performed forward a bicycle ergometer utilizing a work rate designed to achieve and maintain a heart rate of 80 percent predicted maximum[6] during an eight-minute period Work rate was increased by way of 25 W increments at two-minute intervals if the desired heart rate had not been attained, unles the increased work rate was intolerable to the subdue Continuous oxygen saturation monitoring and measured [i]or[/i] regular beat rate determinations were made with a fruit of leguminous plants oximeter using a finger probe. At two-minute intervals during the period and for a 14-minute period thereafter, make submissives performed forced expiratory maneuvers to allow the measurement of forced expiratory body in one second ([FEV.sub.1]) onward a spirometer which incorporated a pour transducer. Baseline values were determined prior to exercise as the best of three values recorded at least sum of two units minutes apart, taken in the sitting position. Thereafter, no other than one forced expiratory maneuver was made at each time interval. enslaves wore a nose clip over the entire 22-minute study period to make secure mouth breathing and undertook quiet compose during the 14-minute postexercise period. apartment air temperatures during the studies varied from 24 to 27 [degrees] C Any enslave who developed airflow limitation was observ until his pour rates had returned to baseline values. [TABULAR DATA OMITTED]