title: Ambulatory pulse oximetry monitoring in Japanese COPD outpatients not receiving oxygen therapy.
abstract: BACKGROUND
  It remains unknown whether desaturation profiles during daily living are associated with prognosis in patients with chronic obstructive pulmonary disease (COPD). Point measurements of resting oxygen saturation by pulse oximetry (SpO2) and partial pressure of arterial oxygen (PaO2) are not sufficient for assessment of desaturation during activities of daily living. A small number of studies continuously monitored oxygen saturation throughout the day during activities of daily living in stable COPD patients. This study aims to analyse the frequency of desaturation in COPD outpatients, and investigate whether the desaturation profile predicts the risk of exacerbation.
  
  
  METHODS
  We studied stable COPD outpatients not receiving supplemental oxygen therapy. Baseline assessments included clinical assessment, respiratory function testing, arterial blood gas analysis, body mass index, and the COPD Assessment Test (CAT). Patients underwent 24-hour ambulatory monitoring of SpO2 during activities of daily living. Exacerbations of COPD and death from any cause were recorded.
  
  
  RESULTS
  Fifty-one patients were enrolled in the study, including 12 current smokers who were excluded from the analyses in case high serum carboxyhaemoglobin concentrations resulted in inaccurately high SpO2 readings. The mean percent predicted forced expiratory volume in one second (%FEV1) was 50.9%. The mean proportion of SpO2 values below 90% was 3.0% during the day and 7.4% during the night. There were no daytime desaturators, defined as ≥ 30% of daytime SpO2 values below 90%. Twenty-one exacerbations occurred in 13 patients during the mean follow-up period of 26.4 months. Univariate and multivariate Cox proportional hazards analyses did not detect any significant factors associated with exacerbation.
  
  
  CONCLUSIONS
  Our 24-hour ambulatory oximetry monitoring provided precise data regarding the desaturation profiles of COPD outpatients. Both daytime and nighttime desaturations were infrequent. The proportion of ambulatory SpO2 values below 90% was not a significant predictor of exacerbation.
authors.affiliation: Department of Respiratory Medicine, Osaka Police Hospital, 10-31 Kitayama-cho, Tennoji-ku, Osaka 543-0035, Japan.
authors.forename: Seigo
authors.initials: S
authors.lastname: Minami
authors.affiliation: Department of Respiratory Medicine, Osaka Police Hospital, 10-31 Kitayama-cho, Tennoji-ku, Osaka 543-0035, Japan.
authors.forename: Suguru
authors.initials: S
authors.lastname: Yamamoto
authors.affiliation: Department of Respiratory Medicine, Osaka Police Hospital, 10-31 Kitayama-cho, Tennoji-ku, Osaka 543-0035, Japan.
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Ogata
authors.affiliation: Department of Internal Medicine, National Hospital Organization Kinki-Chuo Chest Medical Center, 1180 Nagasone-cho, Kita-ku, Sakai, Osaka 591-8555, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Nakatani
authors.affiliation: Department of Respiratory Medicine, Allergy and Rheumatic Diseases, Osaka University Graduate School of Medicine, 2-2 Yamada-oka, Suita, Osaka 565-0871, Japan.
authors.forename: Yoshiko
authors.initials: Y
authors.lastname: Takeuchi
authors.affiliation: Osaka Prefectural Medical Center for Respiratory and Allergic Diseases, 3-7-1 Habikino, Osaka 583-8588, Japan.
authors.forename: Masanari
authors.initials: M
authors.lastname: Hamaguchi
authors.affiliation: Department of Respiratory Medicine, Osaka Police Hospital, 10-31 Kitayama-cho, Tennoji-ku, Osaka 543-0035, Japan.
authors.forename: Taro
authors.initials: T
authors.lastname: Koba
authors.affiliation: Department of Respiratory Medicine, Osaka Police Hospital, 10-31 Kitayama-cho, Tennoji-ku, Osaka 543-0035, Japan.
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Komuta
keywords: Activities of daily living; Chronic obstructive pulmonary disease (COPD); Desaturator; Exacerbation; Outpatients; Pulse oximetry
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