Critical Care |

Diagnostic Value of Passive Leg Raise Induced Changes in Carotid Artery Flow Time to Predict Fluid Responsiveness in Critically Ill Patients FREE TO VIEW

Patton Thompson, MD; Rodrigo Cavallazzi; Juan Guardiola; Jason Mann; Caitlin Lantier; Mohamed Saad
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University of Louisville, Louisville, KY

Chest. 2015;148(4_MeetingAbstracts):231A. doi:10.1378/chest.2260957
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SESSION TITLE: Critical Care Posters I

SESSION TYPE: Original Investigation Poster

PRESENTED ON: Wednesday, October 28, 2015 at 01:30 PM - 02:30 PM

PURPOSE: Difficulties in the accurate assessment of intravascular volume and fluid responsiveness in critically ill patients are frequently encountered. The Carotid Artery is an easily accessible structure that is amenable to bedside ultrasonography. Pulsed Wave Doppler (PWD) can be used to calculate the Carotid Corrected Flow Time (FTC). We sought to determine whether passive leg raise (PLR) induced changes in Carotid FTC are able to predict fluid responsiveness compared to a 15% increase in Stroke Volume (SV) detected by the Flotrac/Vigileo (FV) monitor in critically ill adults.

METHODS: Patients with femoral arterial lines, rhythm abnormalities, intra-abdominal hypertension, pregnancy, lower extremity amputation, and Carotid endarterectomy were excluded. Carotid FTC measurements were taken by using the linear transducer with PWD in the long axis of the Common Carotid Artery and recording the systolic ejection time corrected for the heart rate (FTC = (Systolic Ejection Time) / √(Cycle Time)). Carotid FTC and SV were recorded at baseline in the 45° semi-recumbent position. Each patient was then laid flat and the legs were raised to 45°. The max SV was recorded during a 3 min PLR and Carotid FTC was measured at 1, 2, and 3 min with the max value being recorded. Fluid responders were defined as a 15% increase in SV on the FV.

RESULTS: We enrolled 14 patients. Using an increase of 24.6% in the Carotid FTC in response to PLR to predict fluid responsiveness the ROC was .771 +/- .141. Sensitivity was 66.7%, Specificity 87.5%, +LR 5.33 and -LR .381.

CONCLUSIONS: A 24.6% increase in the Carotid FTC in response to a PLR is a reasonably accurate test for fluid responsiveness in critically ill patients that warrants further study in larger clinical trials validated against a variety of cardiac output monitors.

CLINICAL IMPLICATIONS: This method is very attractive due to the ease of access to the Carotid, reproducibility, low cost, and since the FTC is a measurement of time, the angle of insonation should be inconsequential, making the exam technically easy to perform. Small studies have investigated the use of Carotid FTC to assess volume status in patients donating blood as well as patients presenting with clinical dehydration. This is the first study to our knowledge to investigate the use of Carotid FTC in critically ill patients with FV monitors, and to compare the tests performance to what many consider the gold standard for fluid responsiveness: a >15% increase in SV with PLR.

DISCLOSURE: The following authors have nothing to disclose: Patton Thompson, Rodrigo Cavallazzi, Juan Guardiola, Jason Mann, Caitlin Lantier, Mohamed Saad

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