Can Quantitative Capnometry Differentiate Between Cardiac and Obstructive Causes of Respiratory Distress?

• Published in: Chest Vol. 113; no. 2; pp. 323 - 326
• Main Authors: Brown, Lawrence H., Gough, John E., Seim, Rosa H.
• Format: Journal Article
• Language: English
• Published: Northbrook, IL Elsevier Inc 01.02.1998; American College of Chest Physicians
• Subjects: Adult; Aged; Airway Obstruction - complications; Airway Obstruction - diagnosis; Asthma; Asthma - complications; Asthma - diagnosis; Biological and medical sciences; Blood Pressure - physiology; Capnography; Carbon dioxide; Carbon Dioxide - metabolism; Chi-Square Distribution; Chronic obstructive pulmonary disease; Chronic obstructive pulmonary disease, asthma; congestive heart failure; Dyspnea; Dyspnea - diagnosis; Dyspnea - etiology; Edema; Emergency medical care; emergency medical services; Female; Forecasting; gas exchange; Heart Diseases - complications; Heart Diseases - diagnosis; Heart failure; Heart Failure - complications; Heart Failure - diagnosis; Heart Rate - physiology; Hospitals; Humans; Intervention; Lung Diseases, Obstructive - complications; Lung Diseases, Obstructive - diagnosis; Male; Medical sciences; Middle Aged; Observational studies; Patients; Peak Expiratory Flow Rate - physiology; Physicians; Pneumology; Prospective Studies; Pulmonary Edema - complications; Pulmonary Edema - diagnosis; Radiography, Thoracic; Reproducibility of Results; Respiration - physiology; respiration disorders; Respiratory Insufficiency - diagnosis; Respiratory Insufficiency - etiology; Respiratory Sounds - physiopathology; Statistical analysis; Sweating - physiology; Tidal Volume; Time Factors; Vital signs; emergency medical services; carbon dioxide; congestive heart failure; asthma; gas exchange; respiration disorders; Human; Heart failure; Expired air; Left; Respiratory disease; Carbon dioxide; Cardiovascular disease; Exploration; Quantity; Differential diagnostic; Asthma; Dyspnea; Etiology; Heart disease; Obstructive pulmonary disease; Gas exchange
• ISSN: 0012-3692; 1931-3543
• DOI: 10.1378/chest.113.2.323

To determine whether quantitative measurement of end-tidal carbon dioxide (ETCO2) can differentiate between cardiac and obstructive causes of respiratory distress. Prospective observational study. Emergency department (ED) of a tertiary care hospital. Adult patients who presented to the ED with moderate-to-severe dyspnea. Patients were excluded if they were unable to cooperate with the performance of peak expiratory flow rate (PEFR) or ETCO2 tests, were younger than 18 years of age, or had received prehospital intervention for their respiratory distress. Physicians obtained an ETCO2 level and PEFR prior to ED pharmacologic intervention. A hand-held capnometer with digital read-out was used to obtain the ETCO2 level. The patient's age, sex, initial vital signs, breath sounds and medication history, the presence or absence of diaphoresis and/or orthopnea, the duration of symptoms, the chest radiograph interpretation, and final diagnosis were also recorded. Forty-two patients were eligible for inclusion in the analysis. The mean ETCO2 level was 31.1±9.4 mm Hg; the mean PEFR was 161.3±53.1 L/min. The ETCO2 levels for pulmonary edema/congestive heart failure (CHF) patients differed significantly from those of asthma/COPD patients (27.1±7.8 mm Hg vs 33.4±9.6 mm Hg; p=0.0375). However, no single ETCO2 level was found to be a reliable predictor of diagnosis. ETCO2 levels for pulmonary edema/CHF patients differ significantly from those of asthma/COPD patients. However, no single ETCO2 level reliably differentiates between the two disease processes.