title: Body mass index moderates the effects of portable oxygen transport modality on 6-minute walk distance in patients with COPD.
abstract: OBJECTIVE
  While portable, supplemental oxygen is often necessary for patients with chronic obstructive pulmonary disease (COPD) to retain independence, it may provide functional limitations because of the increased workload imposed. This issue may result in nonuse, creating a need to identify carrying modalities that optimize transport. This study assessed the effects of 3 methods of portable oxygen transport on 6-minute walk distance (6 MWD), rate of perceived exertion (RPE), heart rate (HR), and oxyhemoglobin saturation (SpO2). As weight status is known to impact functional ability in COPD, effects of body mass index (BMI) were also assessed.
  
  
  METHODS
  Data were analyzed using the mixed-model procedure to test for effects of transport modality (reference, rolling cart, backpack, shoulderstrap), time (minutes 1-6), BMI, non-overweight, overweight, and interactions of these variables on outcome parameters.
  
  
  RESULTS
  A main effect of condition was found for 6 MWD, and an interaction of condition × BMI was found for HR and RPE, and of time × BMI for 6 MWD and SpO2. Participants walked the least distance in rolling cart condition, which was also characterized by the greatest RPE. For the overweight group, HR was least in the reference compared with other conditions; but for the non-overweight group, the opposite pattern was observed. At latter time points, 6 MWD was greater in the non-overweight group, while SpO2 was reduced.
  
  
  CONCLUSIONS
  Results demonstrate that transport modality of portable oxygen exerts differential effects on functional performance in COPD patients and that BMI may moderate underlying physiologic factors that contribute to performance outcomes.
authors.affiliation: Department of Human Ecology, Youngstown State University, Youngstown, Ohio (Dr Pohle-Krauza); Summa Health System, Akron City Hospital, Akron, Ohio (Drs McCarroll, Latta, DiNuoscio, and Krauza and Mr Pannikottu); Northeast Ohio Medical University, Rootstown (Mr Gothard); Children's Hospital Medical Center, Akron, Ohio (Ms Volsko); and Biotstats, Inc, Canton, Ohio (Mr Gothard).
authors.forename: Rachael J
authors.initials: RJ
authors.lastname: Pohle-Krauza
authors.forename: Michele L
authors.initials: ML
authors.lastname: McCarroll
authors.forename: Kurian
authors.initials: K
authors.lastname: Pannikottu
authors.forename: Tiffany N
authors.initials: TN
authors.lastname: Latta
authors.forename: David R
authors.initials: DR
authors.lastname: DiNuoscio
authors.forename: Teresa A
authors.initials: TA
authors.lastname: Volsko
authors.forename: M David
authors.initials: MD
authors.lastname: Gothard
authors.forename: Matthew L
authors.initials: ML
authors.lastname: Krauza
mesh_terms: D000203:Activities of Daily Living; D000368:Aged; D015992:Body Mass Index; D016503:Drug Delivery Systems / Q000379:methods / Q000592:standards; D005080:Exercise Test / Q000379:methods; D005260:Female; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D017063:Outcome Assessment, Health Care; D010101:Oxygen Consumption; D010102:Oxygen Inhalation Therapy / Q000295:instrumentation / Q000379:methods; D010108:Oxyhemoglobins / Q000032:analysis; D005082:Physical Exertion; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis / Q000378:metabolism / Q000503:physiopathology / Q000523:psychology / Q000628:therapy; D011788:Quality of Life; D016138:Walking / Q000502:physiology*
chemical_list: D010108:Oxyhemoglobins