Monitoring breathing rate at home allows early identification of COPD exacerbations.
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.
Fundación de Investigación Sanitaria Illes Balears (FISIB), Palma de Mallorca, Madrid. Electronic address: aina.yanez@caubet-cimera.es.
Aina M
AM
Yañez
Fundación de Investigación Sanitaria Illes Balears (FISIB), Palma de Mallorca, Madrid.
Dolores
D
Guerrero
Airproducts Sud Europa, Madrid.
Rigoberto
R
Pérez de Alejo
Servicio de Neumología, Hospital Universitario La Paz, Instituto de Investigación La Paz (IdiPAZ), Madrid.
Francisco
F
Garcia-Rio
Servicio de Neumología, Hospital Clínico San Carlos, Facultad de Medicina, Universidad Complutense, Madrid.
Jose Luis
JL
Alvarez-Sala
Servicio de Neumología, Hospital Clínico San Carlos, Facultad de Medicina, Universidad Complutense, Madrid.
Miriam
M
Calle-Rubio
Hospital Universitario Puerta de Hierro, Majadahonda, Madrid.
Rosa Malo
RM
de Molina
Hospital Universitario Puerta de Hierro, Majadahonda, Madrid.
Manuel
M
Valle Falcones
Hospital Universitario Puerta de Hierro, Majadahonda, Madrid.
Piedad
P
Ussetti
Servei Pneumologia, Hospital Universitari Son Espases, Palma Mallorca.
Jaume
J
Sauleda
Servicio de Neumología, Hospital de La Princesa, Madrid.
Enrique Zamora
EZ
García
Servicio de Neumología, Hospital Gregorio Marañón, Madrid.
Jose Miguel
JM
Rodríguez-González-Moro
Airproducts Sud Europa, Madrid.
Mercedes
M
Franco Gay
Ib-salut, Área de Salut de Menorca, Menorca.
Maties
M
Torrent
Thorax Institute, Hospital Clínic, Institut d'Investigacions Biomediques Agustí Pi i Sunyer (IDIBAPS), Universitat Barcelona, CIBER Enfermedades Respiratorias (CIBERES), and Fundación de Investigación Sanitaria Illes Balears (FISIB) Mallorca, Spain.
Alvar
A
Agustí
D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D006760:Hospitalization; D006801:Humans; D008297:Male; D018670:Monitoring, Ambulatory / Q000379:methods*; D010102:Oxygen Inhalation Therapy; D011446:Prospective Studies; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis / Q000503:physiopathology* / Q000628:therapy; D012372:ROC Curve; D012119:Respiration; D015656:Respiratory Mechanics / Q000502:physiology*; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D013997:Time Factors