Significance of respiratory artifact in the electrocardiogram

Electrocardiographic artifact is generally considered to be a nuisance. Respiratory artifact, however, is a physiologic signal that may carry useful diagnostic information. Our goal was to evaluate the characteristics, prevalence, and clinical significance of respiratory artifact observed in electrocardiograms (ECGs). ECGs exhibiting repetitive microoscillations were systematically collected. The morphologic characteristics of the microoscillations were analyzed and their association with the respiratory cycle was evaluated using simultaneous respiratory waveform tracings. The presence and rate of respiratory artifact were correlated with the patient's clinical status, including medical diagnoses and the need for ventilatory support. During a 30-month period, respiratory artifact was detected in 320 12-lead ECGs. It was best seen in leads II, III, aVF, and V5. Respiratory artifact occurred during the inspiratory phase and its rate correlated precisely with objective measures of the respiratory rate. The majority of patients with respiratory artifact revealed diseases of the respiratory (26.6%) and circulatory systems (24.0%) and, of note, respiratory artifact was never detected in patients with normal cardiorespiratory function; 43.5% of patients with respiratory artifact required ventilatory support, including 28.2% requiring continuous mechanical ventilation. Successful treatment of the underlying condition resulted in a decrease in the rate or in complete disappearance of the respiratory artifact. In conclusion, respiratory artifact is commonly seen in routine 12-lead ECGs of hospitalized patients. It is associated with a high-risk state of increased work of breathing due to either compromised cardiac or pulmonary function. Additionally, the presence of respiratory artifact enables precise evaluation of the respiratory rate-a commonly miscalculated vital sign.