Kliewer Mark A, Dyke William B, Birch Christopher W, Bagley Anjuli R
Department of Radiology, University of Wisconsin-Madison, Madison, Wisconsin, USA.
University of Minnesota School of Medicine, Minneapolis, Minnesota, USA.
J Ultrasound Med. 2021 Feb;40(2):359-367. doi: 10.1002/jum.15410. Epub 2020 Jul 29.
To characterize fluctuations in peak systolic velocities (PSVs) in Doppler waveforms of the carotid artery in patients with and without obstructive airway disease and in volunteers subjected to incremental levels of airway resistance in an experimental model.
The PSV variation in common carotid waveforms was measured in 100 patients who had had a carotid ultrasound examination and no respiratory or carotid disease. This was compared to that of patients who had this study during an admission for acute exacerbation of chronic obstructive pulmonary disease (COPD). The PSV variation was correlated with pulmonary function testing. In addition, 14 healthy volunteers were asked to breathe through 5 resistors. Simultaneous recordings were made of Doppler waveforms in the common carotid artery, cardiac activity, and respiration. Peak systolic velocity changes from inspiration to expiration were calculated.
Of the 100 patients without respiratory disease, the magnitude of the PSV variation averaged 6.3 cm/s. Of the 33 patients with COPD, the PSV variation averaged 16.5 cm/s. Nineteen of the 33 patients with COPD had concurrent pulmonary function testing; there was a statistically significant correlation between the PSV variation and forced vital capacity and forced expiratory volume indices. For the volunteers, mean velocity changes were 7.1, 6.6, 8.3, 15.1, and 16.1 cm/s for 0.00-, 2.15-, 3.27-, 3.58-, and 5.77-cm H O/L/s levels of breathing resistance, respectively. There was a statistically significant relationship between an increasing airway load and the decline in PSV during inspiration (P = .02).
The PSV variation is greater in patients with increased airway resistance. Similar changes are evident in volunteers breathing into resistors. These findings likely reflect pulsus paradoxus.
