Abstract
BackgroundCorrected 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 methodsNormotensive 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.ResultsTwenty 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).ConclusionsIn this study of normotensive patients, there were no detected differences in CFTc or CBF pre and post-intubation with mechanical ventilation.
Highlights
Hypotension and respiratory failure characterize some of the most critically ill conditions treated in emergency departments and intensive care units
There exist some publications on corrected carotid flow time (CFTc) and carotid blood flow (CBF) that suggest their usefulness in determining fluid status and responsiveness in non-ventilated patients [5,7,8]
A systematic review including studies of ventilated and non-ventilated patients supports the integration of carotid artery ultrasound (US) in hypotensive patients in order to predict fluid responsiveness [9]
Summary
Hypotension and respiratory failure characterize some of the most critically ill conditions treated in emergency departments and intensive care units. There has been much research focused on differentiating which hypotensive patients will respond to fluid boluses and which will not [1,2,3,4]. Both invasive and non-invasive means of predicting fluid responsiveness have been investigated [5,6]. There exist some publications on corrected carotid flow time (CFTc) and carotid blood flow (CBF) that suggest their usefulness in determining fluid status and responsiveness in non-ventilated patients [5,7,8]. We investigated the impacts of mechanical ventilation on CFTc and CBF
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