The Use of Pulse Oximetry to Determine Hypoxemia in Acute Exacerbations of COPD

Abstract

Background: There is little evidence that the guideline-recommended oxygen saturation of 92% is the best cut-off point for detecting hypoxemia in COPD exacerbations. Objective: To detect and validate pulse oximetry oxygen saturation cut-off values likely to detect hypoxemia in patients with aeCOPD, to explore the correlation between oxygen saturation measured by pulse oximetry and hypoxemia or hypercapnic respiratory failure. Methodology: Cross-sectional study nested in the IRYSS-COPD study with 2,181 episodes of aeCOPD recruited between 2008 and 2010 in 16 hospitals belonging to the Spanish Public Health System. Data collected include determination of oxygen saturation by pulse oximetry upon arrival in the emergency department (ED), first arterial blood gasometry values, sociodemographic information, background medical history and clinical variables upon ED arrival. Logistic regression models were performed using as the dependent variables hypoxemia (PaO2 < 60 mmHg) and hypercapnic respiratory failure (PaO2 < 60 mmHg and PaCO2 > 45). Optimal cut-off points were calculated. Results: The correlation coefficient between oxygen saturation and pO2 measured by arterial blood gasometry was 0.89. The area under the curve (AUC) for the hypoxemia model was 0.97 (0.96–0.98) and the optimal cut-off point for hypoxemia was an oxygen saturation of 90%. The AUC for hypercapnic respiratory failure was 0.90 (0.87–0.92) and the optimal cut-off point was an oxygen saturation of 88%. Conclusions: Our results support current recommendations for ordering blood gasometry based on pulse oximetry oxygen saturation cut-offs for hypoxemia. We also provide easy to use formulae to calculate pO2 from oxygen saturation measured by pulse oximetry.

Keywords:

• diagnosis
• emergency department
• respiratory failure
• validation

Acknowledgments

We acknowledge editorial assistance of Patrick Skerret. The IRYSS- COPD group included the following co-investigators: Dr. Jesús Martínez-Tapias (Hospital Virgen de las Nieves, Granada); Alba Ruiz (Hospital de Motril, Granada); Dr. Eduardo Briones (Unidad de Epidemiología. Distrito Sanitario Sevilla); Dra. Silvia Vidal (Unidad de Investigación, Hospital Costa del Sol, Marbella); Dr. Emilio Perea-Milla, Francisco Rivas (Servicio de Epidemiología, Hospital Costa del Sol, Málaga – REDISSEC); Dr. Maximino Redondo (Servicio de Laboratorio, Hospital Costa del Sol, Málaga-REDISSEC); Javier Rodríguez Ruiz (Responsable de Enfermería del Área de Urgencias, Hospital Costa del Sol, Málaga); Dra. Marisa Baré (Epidemiología y Evaluación, Corporació Sanitaria Parc Taulí-CSPT, Sabadell REDISSEC), Dr. Manel Lujan, Dra. Concepción Montón (Servicio de Neumología, CSPT/REDISSEC); Dra. Amalia Moreno, Dra. Josune Ormaza, Dr. Javier Pomares (Servicio de Neumología, CSPT); Dr. Juli Font (Medicina, Servicio de Urgencias; CSPT), Dra. Cristina Estirado, Dr. Joaquín Gea (­Servicio de Neumología, Hospital del Mar/CIBERES, Barcelona); Dra. Elena Andradas (subdirectora de Promoción de la Salud y Epidemiología del Ministerio de Sanidad, ­Servicios Sociales e Igualdad), Dr. Juan Antonio Blasco (Unidad de Evaluación de ­Tecnologías Sanitarias, ­Agencia Laín Entralgo, Madrid), Dra. Nerea Fernández de ­Larrea (Subdirección General de Tecnología e Innovación Sanitarias. Consejería de Sanidad de la Comunidad de Madrid/REDISSEC); Rosa Girón (Hospital de La ­Princesa, Madrid), María del Puerto Cano Aguirre (Hospital de Torrejón, Madrid); Dr. Jose Luis Lobo (­Servicio de Neumología, Hospital Txagorritxu, Araba); Dra. Esther Pulido (Servicio de Urgencias, Hospital Galdakao-­Usansolo, Bizkaia); Dr. Mikel Sánchez (­Servicio de ­Urgencias, Hospital Galdakao-Usansolo); Dr. Luis Alberto Ruiz (Servicio de Respiratorio, Hospital de Cruces, Bizkaia); Dra. Ane Miren Gastaminza (Hospital San Eloy, Bizkaia); Dra. Eva Tabernero (Servicio de ­Neumología, Hospital de Santa Marina), Carmen Haro (Servicio de Urgencias, Hospital de Santa Marina, Bizkaia); Dr. Ramon Agüero (­Servicio de Neumología, Hospital Marques de Valdecilla, Santander); Dr. Gabriel Gutiérrez (Servicio de Urgencias, Hospital Cruces, ­Bizkaia); Dra. Belén Elizalde (Dirección Territorial de Gipuzkoa); Dr. Felipe Aizpuru (Unidad de Investigación, Hospital Txagorritxu, Álava/REDISSEC); Dra. Inmaculada Arostegui, Irantzu Barrio (Departamento de Matemática Aplicada, Estadística e Investigación Operativa, UPV/EHU- REDISSEC; Amaia Bilbao (Hospital Universitario Basurto/REDISSEC); Dr. Cristóbal Esteban (Servicio de Neumología, Hospital Galdakao-Usansolo, Bizkaia/REDISSEC); Dra. Nerea González, Susana ­Garcia, Iratxe Lafuente, Urko Aguirre; Miren Orive, Ane Anton, Dr. Jose M. Quintana (Unidad de Investigación, Hospital Galdakao-Usansolo, Bizkaia/REDISSEC).