Respiratory artifact: A second vital sign on the electrocardiogram

2015 Cleveland Clinic journal of medicine  
Respiratory artifact: A second vital sign on the electrocardiogram A 57-year-old man hospitalized for treatment of multilobar pneumonia was noted to have a rapid, irregular heart rate on telemetry. He was hypoxemic and appeared to be in respiratory distress. A 12-lead electrocardiogram (ECG) demonstrated atrial fibrillation with rapid ventricular response, as well as what looked like distinct and regular P waves dissociated from the QRS complexes at a rate of about 44/min (Figure 1) . What is
more » ... gure 1) . What is the explanation and clinical significance of this curious finding? What appear to be dissociated P waves actually represent respiratory artifact. 1-3 The sharp deflections mimicking P waves signify the tonic initiation of inspiratory effort; the subsequent brief periods of low-amplitude, high-frequency micro-oscillations represent surface electrical activity associated with the increased force of the accessory muscles of respiration. [1] [2] [3] Surface electromyography noninvasively measures muscle activity using electrodes placed on the skin overlying the muscle. 4 Using simultaneously recorded mechanical respiratory waveform tracings, we have previously demonstrated that the repetitive pseudo-P waves followed by micro-oscillations have a close temporal relationship with the inspiratory phase of respiration. 3 The presence of THE CLINICAL PICTURE FIGURE 1. The patient's electrocardiogram demonstrates atrial fibrillation with rapid ventricular response. In addition, there are regularly spaced, distinct, sharp deflections suggestive of P waves, best seen in the inferior leads (arrows). Broken arrows indicate apparent P waves superimposed on QRS complexes. Apparent dissociated P waves can actually represent respiratory artifact 488
doi:10.3949/ccjm.82a.14134 pmid:26270425 fatcat:emfyz6cvznc3jeyzhtk2hyvfk4