title: Response to symptom-limited exercise in patients with the hepatopulmonary syndrome.
abstract: OBJECTIVE
  To study the response to symptom-limited exercise in patients with the hepatopulmonary syndrome (HPS).
  
  
  METHODS
  The response to maximal cardiopulmonary exercise (CPX) was studied in 5 patients with HPS and compared with 10 case control (normoxemic, NC) cirrhotics (matched for age, gender, etiology and severity of liver disease, tobacco use, and beta-blocker therapy) and 9 hypoxemic control cirrhotics (HC) without clinical evidence of HPS.
  
  
  METHODS
  Cardiopulmonary exercise physiology laboratory in a tertiary care referral center.
  
  
  METHODS
  Cirrhotics referred for CPX as part of their preliver transplantation evaluation.
  
  
  METHODS
  Standard pulmonary function tests and echocardiography were performed to assess resting pulmonary and cardiac function. Peak oxygen consumption (VO2), minute ventilation, arterial blood gases, and dead space (VD/VT) were determined during symptom-limited maximal CPX.
  
  
  RESULTS
  Resting spirometry and lung volumes were similar between HPS and NC subjects, while HC subjects had restrictive physiology. Differences existed in diffusing capacity corrected for hemoglobin and alveolar volume percent predicted (HPS, 45+/-2 vs NC, 68+/-3, p<0.05; vs HC, 70+/-4, p<0.05), PaO2 (HPS, 70+/-5 mm Hg; HC, 79+/-3 mm Hg, vs NC, 102+/-3 mm Hg, p<0.05) and alveolar-arterial (A-a) O2 gradient (HPS, 42+/-8 mm Hg vs HC, 27+/-2 mm Hg, p<0.05; vs NC, 6+/-2 mm Hg, p<0.05). During CPX, HPS patients achieved a lower peak VO2 percent predicted (HPS, 55+/-6 vs NC, 73+/-3, p<0.05; vs HC, 71+/-5, p<0.05) and VO2 at the ventilatory threshold as percent predicted peak VO2 (HPS, 36+/-2 vs NC, 55+/-4, p<0.05; vs HC 55+/-5, p<0.05). While no differences existed in heart rate and breathing reserve, HPS patients had significantly lower PaO2 (HPS, 50+/-5 mm Hg vs NC, 97+/-4 mm Hg, p<0.05; vs HC, 87+/-6 mm Hg, p<0.05), wider A-a O2 gradient (HPS, 73+/-5 mm Hg vs NC, 13+/-3 mm Hg, p<0.05; vs HC, 31+/-5 mm Hg, p<0.05) and higher VD/VT (HPS, 0.36+/-.03 vs NC, 0.18+/-.02, p<0.05; vs HC, 0.28+/-.02, p<0.05) at peak exercise. For HPS patients, VO2 was negatively correlated with VD/VT (r2=0.9) and positively correlated with PaO2 (r2=0.41) at peak exercise.
  
  
  CONCLUSIONS
  Patients with HPS demonstrate a severe reduction in aerobic capacity, beyond that found in cirrhotics without syndrome. The significant hypoxemia and elevated VD/VT at peak exercise suggest that an abnormal pulmonary circulation contributes to further exercise limitation in patients with HPS.
authors.affiliation: Department of Medicine, Tupper Research Institute, New England Medical Center, Tufts University School of Medicine, Boston, MA 02166, USA.
authors.forename: S K
authors.initials: SK
authors.lastname: Epstein
authors.forename: M D
authors.initials: MD
authors.lastname: Zilberberg
authors.forename: C
authors.initials: C
authors.lastname: Jacoby
authors.forename: R L
authors.initials: RL
authors.lastname: Ciubotaru
authors.forename: L M
authors.initials: LM
authors.lastname: Kaplan
mesh_terms: D000328:Adult; D002245:Carbon Dioxide / Q000097:blood; D004452:Echocardiography; D005080:Exercise Test; D005260:Female; D006339:Heart Rate; D006801:Humans; D000860:Hypoxia / Q000503:physiopathology; D008103:Liver Cirrhosis / Q000503:physiopathology; D008107:Liver Diseases / Q000503:physiopathology*; D008171:Lung Diseases / Q000097:blood / Q000503:physiopathology*; D008176:Lung Volume Measurements; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood; D011659:Pulmonary Gas Exchange; D015656:Respiratory Mechanics; D013147:Spirometry; D013318:Stroke Volume; D013577:Syndrome; D016277:Ventricular Function, Left
chemical_list: D002245:Carbon Dioxide; D010100:Oxygen