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. 2021 Dec 21;13(12):e20587.
doi: 10.7759/cureus.20587. eCollection 2021 Dec.

Sonographic Assessment of the Effects of Mechanical Ventilation on Carotid Flow Time and Volume

Jessica I Schleifer  1 , Lauren Ann J Selame  2 , Jorge Short Apellaniz  3 , Michael Loesche  4   2 , Hamid Shokoohi  4 , Carolyn Mehaffey  5 , Andrew Liteplo  4
Affiliations

Sonographic Assessment of the Effects of Mechanical Ventilation on Carotid Flow Time and Volume

Jessica I Schleifer et al. Cureus. .

Abstract

Background Corrected carotid flow time (CFTc) and carotid blood flow (CBF) are sonographic measurements used to assess fluid responsiveness in hypotension. We investigated the impacts of mechanical ventilation on CFTc and CBF. Materials and methods Normotensive patients undergoing cardiac surgery were prospectively enrolled. Carotid ultrasound (US) was performed pre and post-intubation. Post-intubation measurements took place after the initiation of mechanical ventilation. To measure CFTc and CBF, a sagittal carotid view was obtained with pulse wave-Doppler (maximum angle 60°). CFTc was calculated with the Bazett formula (CFTc = systolic time/√cycle time). CBF was calculated using CBF (mL/min) = area (cm 2 ) x time average mean velocity (TAMEAN) (cm/sec) x 60 (sec/min). The maximum carotid diameter was measured at the level of the thyroid. Results Twenty patients were enrolled. Mean CFTc pre-intubation was 328 ms (SD 43.9 ms) compared to CFTc post-intubation 336 ms (SD 36 ms). There was no significant difference between pre and post-intubation CFTc (mean differences=-0.008; t(19)=-0.71, p=.49). Mean CBF pre-intubation was 487 mL/min (SD 176 mL/min) compared to CBF post-intubation 447 mL/min (SD 187 mL/min). There was no significant difference between pre and post-intubation CBF (mean differences= 40; t(19)=1.24, p=.23). Conclusions In this study of normotensive patients, there were no detected differences in CFTc or CBF pre and post-intubation with mechanical ventilation.

Keywords: carotid blood flow; carotid flow time; carotid ultrasound; critical care ultrasound; mechanical ventilation.

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Conflict of interest statement

The authors have declared financial relationships, which are detailed in the next section.

Figures

Figure 1
Figure 1. Carotid Artery Diameter
The carotid artery vessel diameter was measured in transverse at the height of the thyroid gland or 3 cm below the carotid bulb if no thyroid gland were present. Pulse wave Doppler measurements were obtained at this same location. The diameter was transferred to the longitudinal image to allow the ultrasound machine to calculate the area and flow volume.
Figure 2
Figure 2. Flow Time and Cycle Time
Pulse wave Doppler with measurement of flow time and cycle time over three cycles
Figure 3
Figure 3. Flow Volume
Pulse wave Doppler with measurement of flow volume, Time Average Mean Velocity (TAMEAN). The vascular diameter was measured in transverse at the same location as the doppler image. The diameter result was transferred to the longitudinal image so the ultrasound machine could calculate the area and the flow volume.
Figure 4
Figure 4. Corrected Carotid Flow Time
Pre and post-intubation corrected carotid flow time (CFTc) is depicted for each subject with individual subjects represented by each red line and mean values represented by the blue line.
Figure 5
Figure 5. Carotid Blood Flow
Pre and post-intubation carotid blood flow (CBF) is depicted for each subject with individual subjects represented by each red line and mean values represented by the blue line.
See this image and copyright information in PMC

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