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A novel device to measure long-term oxygen therapy use: Design and application for identifying adherence patterns

Publication Date
  • Health Sciences
  • Rehabilitation And Therapy|Engineering
  • Biomedical
  • Mathematics
  • Medicine


Failure of patients to adhere to the medical treatment of chronic obstructive pulmonary disease (COPD) compromises patient health and increases health care costs. Current methods for measuring patient adherence to long-term oxygen therapy (LTOT) fail to measure the actual amount of time the patient is inhaling oxygen and the pattern of oxygen use within the day. A novel oxygen adherence monitor was developed to address these limitations. The monitor detects whether the oxygen source is turned on and whether the patient is inhaling oxygen through the nasal cannula. The monitor is based on sensing respiratory-related pressure fluctuations in the main oxygen delivery tube and is covertly placed in-line between the oxygen source and the patient. The accuracy of the monitor, as compared to direct-observation, was tested during exercise, daytime wakefulness, and sleep in patients with COPD on LTOT. Results showed that the monitor is capable of objectively measuring whether or not patients with COPD are receiving their treatment. Accuracy may be reduced in patients who are mouth breathers and/or who have frequent episodes of apnea/hypopnea. Beyond measuring the absolute level of adherence, objective monitoring also has the benefit of measuring patterns of therapy use. No systematic method exists for quantifying adherence patterns; thus, a new stochastic method to describe adherence patterns was introduced. The method treated adherence patterns as Markov chains, which allowed statistical comparisons between two patterns to determine if they were similar or not. Available data from asthma inhaler use and continuous positive airway pressure use were used for analysis since LTOT data was unavailable. Results indicated that the method could reliably distinguish between two different patterns. Clinical application of this novel technique may lead to new insights concerning predictors of adherence patterns and adherence promotion interventions for particular adherence patterns. ^

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