Validation of a novel device to objectively measure adherence to long-term oxygen therapy

Autor: Samuel T. Kuna, Sun-Kai V Lin, Daniel K. Bogen
Jazyk: angličtina
Rok vydání: 2008
Předmět:
Zdroj: International Journal of COPD, Vol 2008, Iss Issue 3, Pp 435-442 (2008)
International Journal of Chronic Obstructive Pulmonary Disease
ISSN: 1178-2005
1176-9106
Popis: Long-term oxygen therapy (LTOT) is a well-established treatment for patients with oxygen desaturation due to parenchymal lung diseases (NOT 1980; MRC 1981). In patients with chronic obstructive pulmonary disease (COPD) and hypoxemia at rest, continuous use of LTOT (>15 hours/day) improves survival and quality of life, and reduces the number of hospitalizations (Criner 2000; Pierson 2000). Unfortunately, this therapy is costly, accounting for approximately 30% (US $1.3 billion) of annual Medicare expenditures for durable medical equipment (Dunne 2000). It is likely that many of these dollars are wasted because studies report that many patients do not adhere adequately to this treatment (Howard et al 1992; Granados et al 1997; Avdeev et al 1999). Compounding this problem, current methods used to measure adherence to LTOT probably overestimate actual use. Each type of oxygen source used for LTOT requires a different method to objectively assess patient adherence to treatment. For the oxygen concentrator, average daily use is estimated by recording the concentrator’s hour-meter readings (“power on” time) over a known period of time. For oxygen tanks, adherence is estimated by knowing the prescribed flow rate and the number of tanks used. For liquid oxygen, adherence is calculated by weighing the container, knowing the flow rate, and estimating the amount of evaporation and venting from the system. All of the above measures are deficient and probably misleading because: 1) they do not discern whether or not the patient is actually inhaling the oxygen, as opposed to merely having the oxygen source turned on, ie, oxygen expenditure may not reflect oxygen delivery to the patient, and 2) they fail to provide information regarding the timing of oxygen use within the day. The lack of an accurate, objective measure of adherence to LTOT prevents the accurate determination of the optimal duration of daily treatment. In addition, the inability to identify patients with inadequate adherence prevents the development of interventions designed to improve adherence and thereby to increase the effectiveness of this expensive but life-saving treatment. We have developed a novel oxygen adherence monitor to address the above limitations and objectively document when a patient is actually receiving oxygen treatment (Lin et al 2006). The monitor attaches to the oxygen source and detects pressure in the tubing, including the respiratory-related pressure fluctuations transmitted from the nares. The monitor is designed to detect when the oxygen source is turned on and when the patient is actually wearing the nasal cannula and receiving treatment. Our monitor performs measurements every four minutes over a 25-second duration and, for each measurement, identifies one of four conditions: source-on/cannula-on, source-on/cannula-off, source-off/cannula-off, and source-off/cannula-on. Periodic measurement, as opposed to continuous measurement, was selected to extend battery life of the AA battery powered monitor. The design and operating characteristics of the device have been previously detailed and the device has been validated in patients with COPD under controlled conditions during relatively short periods while sitting at rest and walking (Lin et al 2006). The purpose of the current study was to evaluate the monitor’s performance in patients with COPD during wakefulness and sleep over a longer period of time and under less controlled conditions. Some of the results of these studies have been previously reported in the form of an abstract (Lin et al 2005).
Databáze: OpenAIRE
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