title: High pressure versus high intensity noninvasive ventilation in stable hypercapnic chronic obstructive pulmonary disease: a randomized crossover trial.
abstract: BACKGROUND
  High-intensity (high-pressure and high backup rate) noninvasive ventilation has recently been advocated for the management of stable hypercapnic chronic obstructive pulmonary disease (COPD). However, the relative contributions of high inspiratory pressure and high backup rate to ventilator adherence and physiological outcome have not been investigated.
  
  
  METHODS
  Patients with stable hypercapnic COPD (daytime PaCO(2) > 6 kPa) and nocturnal hypoventilation were enrolled. Patients were randomly allocated to high-pressure and high backup rate (high-intensity) and high-pressure and low backup rate (high-pressure) for a 6-week period. At the end of the first treatment period, patients were switched to the alternative treatment. The primary outcome measure was mean nightly ventilator usage.
  
  
  RESULTS
  Twelve patients were recruited, with seven completing the 12-week trial protocol. The mean patient age was 71 ± 8 years, with a forced expiratory volume in one second (FEV(1))/forced vital capacity (FVC) of 50% ± 13% and FEV(1) of 32% ± 12%. The baseline PaCO(2) and PaO(2) were 8.6 ± 1.7 kPa and 7.3 ± 1.4 kPa, respectively. There was no significant difference demonstrated in mean nightly ventilator usage between the high-intensity and high-pressure groups (difference of 4 minutes; 95% confidence interval -45 to 53; P = 0.9). Furthermore, there were no differences in any of the secondary endpoints, with the exception of the respiratory domain of the Severe Respiratory Insufficiency questionnaire, which was lower in the high-intensity arm than in the high-pressure arm (57 ± 11 versus 69 ± 16; P < 0.05).
  
  
  CONCLUSIONS
  There was no additional benefit, in terms of night-time ventilator adherence or any of the other measured parameters, demonstrated by addition of a high backup rate to high-pressure noninvasive ventilation. These data suggest that it is the high-pressure component of the high-intensity noninvasive ventilation approach that plays the important therapeutic role in the management of hypercapnic respiratory failure in COPD patients.
authors.affiliation: Lane Fox Clinical Respiratory Physiology Group, Guy's and St Thomas' NHS Foundation Trust, London, UK. patrick.b.murphy@kcl.ac.uk
authors.forename: Patrick B
authors.initials: PB
authors.lastname: Murphy
authors.forename: Kate
authors.initials: K
authors.lastname: Brignall
authors.forename: John
authors.initials: J
authors.lastname: Moxham
authors.forename: Michael I
authors.initials: MI
authors.lastname: Polkey
authors.forename: A Craig
authors.initials: AC
authors.lastname: Davidson
authors.forename: Nicholas
authors.initials: N
authors.lastname: Hart
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D018592:Cross-Over Studies; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D006935:Hypercapnia / Q000175:diagnosis / Q000503:physiopathology / Q000628:therapy*; D008131:London; D008168:Lung / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D063087:Noninvasive Ventilation; D010349:Patient Compliance; D011312:Pressure; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis / Q000503:physiopathology / Q000628:therapy*; D011788:Quality of Life; D012121:Respiration, Artificial / Q000379:methods*; D016037:Single-Blind Method; D011795:Surveys and Questionnaires; D013997:Time Factors; D016896:Treatment Outcome; D014797:Vital Capacity