Respiratory Variations in Peak Peripheral Artery Velocities and Waveforms for Rapid Assessment of Fluid Responsiveness in Traumatic Shock Patients.

BACKGROUND This study aimed to assess the correlation between the variability of the end-inspiratory and end-expiratory blood flow waveform and fluid responsiveness (FR) in traumatic shock patients who underwent mechanical ventilation by evaluating peripheral arterial blood flow parameters. MATERIAL AND METHODS A cohort of 60 patients with traumatic shock requiring mechanical ventilation-controlled breathing received ultrasound examinations to assess the velocity of carotid artery (CA), femoral artery (FA) and brachial artery (BA). A rehydration test was performed in which of 250 mL of 0.9% saline was administered within 30 min between the first and second measurement of cardiac output by echocardiography. Then, all patients were divided into 2 groups, a responsive group (FR+) and a non-responsive group (FR-). The velocity of end-inspiratory and end-expiratory peripheral arterial blood flow of all patients was ultrasonically measured, and the variability were measured between end-inspiratory and end-expiratory. RESULTS The changes in the end-inspiratory and end-expiratory carotid artery blood flow velocity waveforms of the FR+ groups were significantly different from those of the FR- group (P<0.001). A statistically significant difference in ΔVmax (CA), ΔVmax (BA), and ΔVmax (FA) between these 2 groups was found (all P<0.001). The ROC curve showed that DVmax (CA) and ΔVmax (BA) were more sensitive values to predict FR compared to ΔVmax (FA). The sensitivity of ΔVmax (CA), ΔVmax (FA), and ΔVmax (BA) was 70.0%, 86.7%, and 93.3%, respectively. CONCLUSIONS The study showed that periodic velocity waveform changes in the end-inspiratory and end-expiratory peripheral arterial blood flow can be used for quick assessment of fluid responsiveness.

A novel methodology for rat aortic pulse wave velocity assessment by Doppler ultrasound: validation against invasive measurements.

There is still lack of a simple, accurate, and noninvasive method for rat aortic pulse wave velocity (PWV) measurement, especially the transit distance cannot be accurately measured. Thus, we aimed to derive an equation for aortic transit distance as a function of the nose-to-rump length (L) and to test the hypothesis that aortic PWV measured by new equation combined with Doppler ultrasound (the "equation method") may have stronger correlation with invasive measurements than traditional "body surface method." Two-hundred male Sprague-Dawley (SD) rats (age ranged 5-24 wk) were included in protocol 1, and the aortic transit distances were measured postmortem. In protocol 2, heart-femoral PWV and carotid-femoral PWV were measured by equation method (hfPWVE, cfPWVE) and also by traditional body surface method (hfPWVS, cfPWVS) in another 30 young and 28 old rats. These measurements were then validated against invasively measured hfPWVI and cfPWVI from the same animal. Protocol 1 showed that the heart-femoral transit distance could be calculated by 0.6086 × L - 1.6523, and the carotid-femoral transit distance by 0.4614 × L + 1.8335. In protocol 2, in young rats, the Pearson r between hfPWVE, cfPWVE, hfPWVS, and cfPWVS and their corresponding invasive measurement were 0.8962, 0.8509, 0.8387, and 0.7828, respectively (all P < 0.0001). In the old group, the results were 0.8718, 0.7999, 0.8330, and 0.7112, respectively (all P < 0.0001). The hfPWVE and cfPWVE showed better agreement with hfPWVI and cfPWVI and lower intra- and interobserver variability compared with hfPWVS and cfPWVS in both groups. These findings demonstrate that this novel methodology provides a simple and reliable method for rat noninvasive aortic PWV measurement.NEW & NOTEWORTHY First, when measuring aortic PWV in SD rat models, the heart-femoral transit distance can be estimated by 0.6086 × L - 1.6523, and the carotid-femoral distance transit distance can be estimated by 0.4614 × L + 1.8335, where L (in mm) is nose-to-rump length. Second, this novel methodology for aortic PWV measurement was validated with a closer correlation with the invasive measurements than traditional approach in young and old rats. Third, this study provides a simple and reliable method for rat noninvasive aortic PWV measurement.