Chest
Volume 142, Issue 6, December 2012, Pages 1524-1529
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Original Research
COPD
Monitoring Breathing Rate at Home Allows Early Identification of COPD Exacerbations

https://doi.org/10.1378/chest.11-2728Get rights and content

Background

Respiratory frequency increases during exacerbations of COPD (ECOPD). We hypothesized that this increase can be detected at home before ECOPD hospitalization.

Methods

To test this hypothesis, respiratory frequency was monitored at home daily for 3 months in 89 patients with COPD (FEV1, 42.3% ± 14.0%; reference) who were receiving domiciliary oxygen therapy (9.6 ± 4.0 h/d).

Results

During follow-up, 30 patients (33.7%) required hospitalization because of ECOPD. In 21 of them (70%), mean respiratory frequency increased (vs baseline) during the 5 days that preceded it (from 15.2 ± 4.3/min to 19.1 ± 5.9/min, P < .05). This was not the case in patients without ECOPD (16.1 ± 4.8/min vs 15.9 ± 4.9/min). Receiver operating characteristic analysis showed that 24 h before hospitalization, a mean increase of 4.4/min (30% from baseline) provided the best combination of sensitivity (66%) and specificity (93%) (area under the curve [AUC] = 0.79, P < .05). Two days before hospitalization, a mean increase of 2.3/min (15% change from baseline) was associated with a sensitivity of 72% and a specificity of 77% (AUC = 0.76, P < .05).

Conclusions

Respiratory frequency can be monitored daily at home in patients with COPD receiving domiciliary oxygen therapy. In these patients, breathing rate increases significantly days before they require hospitalization because of ECOPD. This may offer a window of opportunity for early intervention.

Section snippets

Study Design and Ethics

This prospective cohort study was conducted in six tertiary referral hospitals in Spain, five in Madrid (Hospital La Paz-Instituto de Investigación La Paz, Hospital La Princesa, Hospital Puerta de Hierro, Hospital Gregorio Marañón, and Hospital Clínico San Carlos), and one in Palma de Mallorca (Hospital Universitari Son Espases). After the patient signed the informed consent, being aware of its nature and goals, respiratory frequency was monitored at home (see the “Study Design and Ethics”

Results

Between October 2009 and March 2010, 126 patients were recruited. Thirty-seven of them were excluded from analysis for different reasons: 12 because of technical problems with the monitor resulting in insufficient data for analysis and 25 because of poor compliance with oxygen therapy so that they did not have enough data to calculate both the baseline and random periods. Hence, a total of 89 patients were finally included in the analysis. Their mean age was 76.2 ± 6.5 years, 74% of them were

Discussion

This study explores a novel and potentially clinically relevant hypothesis: The increase in respiratory frequency that characterizes the episodes of ECOPD can be detected days before hospitalization. Our results confirm this hypothesis and open the possibility of exploring, in a larger and formally randomized clinical trial, the potential benefits of an early therapeutic intervention during this window of opportunity on relevant clinical outcomes, such as need for hospitalization, length of

Acknowledgments

Author contributions: Dr Yáñez confirms that the study objectives and procedures are honestly disclosed.

Dr Yañez: contributed to conception and design of the original idea, data analysis, and drafting of the manuscript.

Ms Guerrero: contributed to statistical support, data analysis, and drafting of the manuscript.

Dr Pérez de Alejo: contributed to data collection, conception and design of the original idea, data analysis, and drafting of the manuscript.

Dr Garcia-Rio: contributed to data

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Funding/Support: This study was supported by Air Products Sud Europa, Madrid, Spain.

Reproduction of this article is prohibited without written permission from the American College of Chest Physicians. See online for more details.

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