Echocardiographic Study of the Paradoxical Arterial Pulse in Chronic Obstructive Lung Disease

SUMMARY In nine subjects with chronic obstructive pulmonary disease (COPD) and pulsus paradoxus, M-mode echocardiograms showed inspiratory augmentation of right ventricular dimensions and inspiratory decrease of left ventricular diastolic dimensions. In five subjects in whom the echocardiographic transistor was in the subxiphoid position, mean right ventricular dimensions increased during inspiration from 1.4 4 0.20 to 2.96 ± 0.38 cm (p < 0.01). With inspiration, mean left ventricular diastolic dimensions decreased from 4.8 + 0.61 to 3.7 ± 0.63 cm (p < 0.01) in these five subjects. Two-dimensional echocardiograms, performed in three subjects, confirmed inspiratory augmentation of right ventricular cross-sectional area. Similar changes were produced in two normal volunteers by artificial obstruction to breathing. Left ventricular ejection time measurements demonstrated an inspiratory decline in left ventricular stroke volume. Inspiratory filling of the right ventricle is not hampered, but rather is exaggerated in patients with COPD and pulsus paradoxus, and left ventricular stroke volume is reduced during inspiration. Exaggerated variations in intrathoracic pressure alone did not explain pulsus paradoxus. Increased right ventricular filling and stroke volume during inspiration probably play a part. IN 1698 Floyer described inspiratory disappearance of the arterial pulse during attacks of bronchial asthma.' Severe degrees of chronic obstructive airway disease are also known to be associated with weakening of the arterial pulse during inspiration (paradoxical pulse, or pulsus paradoxus).2 However, studies of the mechanism of pulsus paradoxus are recent. Echocardiographic investigations of patients with pulsus paradoxus and cardiac tamponade36 have suggested inspiratory diminution of left ventricular filling, but inspiratory augmentation of right ventricular filling during pulsus paradoxus with cardiac tamponade. The echocardiogram has also been evaluated in the setting of paradoxical pulse with pulmonary embolism.6 We previously described echocardiograms of two patients with chronic obstructive airway disease and pulsus paradoxus.5 These two patients also showed inspiratory augmentation of right ventricular dimension and inspiratory diminution of left ventricular dimension. In this paper we report an investigation of pulsus paradoxus in a larger group of patients and explore the mechanism of this phenomenon in obstructive airway disease. For this study, pulsus paradoxus was defined as an inspiratory decrease of systolic blood pressure of 10 mm Hg or more