title: Exercise testing in survivors of intensive care--is there a role for cardiopulmonary exercise testing?
abstract: OBJECTIVE
  The aims of this study were to assess the feasibility of cardiopulmonary exercise testing (CPET) for the early assessment of cardiorespiratory fitness in general adult intensive care unit (ICU) survivors and to characterize the pathophysiology of exercise limitation in this population.
  
  
  METHODS
  Fifty general ICU survivors (ventilated for ≥ 5 days) performed a maximal cycle ergometer CPET within 6 weeks of hospital discharge. Health-related quality of life was measured by the Medical Outcome Study Short Form 36 version 2.0 questionnaire.
  
  
  RESULTS
  Fifty patients (median age, 57 years; median Acute Physiology And Chronic Health Evaluation II score, 16) completed a CPET 24 ± 14 days after hospital discharge with no adverse events. Significant exercise limitation was present with peak Vo(2) 56% ± 16% predicted and anaerobic threshold (AT) 41% ± 13% of peak predicted Vo(2). Prospectively stratified subgroup comparison showed that patients ventilated for 14 days or more had a significantly lower AT and peak Vo(2) than those ventilated for 5 to 14 days (AT: 9.6 vs 11.7 mL/kg per minute O(2), P = .009; peak Vo(2): 12.9 vs 15.3 mL/kg per minute O(2), P = .022). At peak exercise, heart rate reserve was 25% ± 14%, breathing reserve was 47% ± 19%, and the respiratory exchange ratio was 0.96 ± 0.11. Ventilatory equivalents for CO(2) (Eqco(2)) were 39 ± 9.
  
  
  CONCLUSIONS
  Significant exercise limitation is evident in patients who have had critical illness. Etiology of exercise limitation appears multifactorial, with general deconditioning and muscle weakness as major contributory factors. Early CPET appears a practical method of assessing exercise capacity in ICU survivors. Cardiopulmonary exercise testing could be used to select patients who may benefit most from a targeted physical rehabilitation program, aid in exercise prescription, and help assess the response to intervention.
authors.affiliation: Manchester Royal Infirmary, M13 9WL Manchester, UK. steve.benington@cmft.nhs.uk
authors.forename: Steve
authors.initials: S
authors.lastname: Benington
authors.forename: David
authors.initials: D
authors.lastname: McWilliams
authors.forename: Jane
authors.initials: J
authors.lastname: Eddleston
authors.forename: Dougal
authors.initials: D
authors.lastname: Atkinson
mesh_terms: D018806:APACHE; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002319:Cardiovascular System / Q000503:physiopathology*; D003422:Critical Care; D005080:Exercise Test; D017079:Exercise Tolerance; D005240:Feasibility Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D012121:Respiration, Artificial / Q000706:statistics & numerical data; D012137:Respiratory System / Q000503:physiopathology*; D017741:Survivors; D013997:Time Factors; D055815:Young Adult