Oesophageal Doppler monitoring is used intraoperatively to guide fluid therapy. The corrected flow time (FTc) of 0.28 seconds is measured during passive leg raising. What does this value indicate and what is the appropriate response?

• A FTc 0.28 s indicates vasodilation; administer noradrenaline
• B FTc 0.28 s is normal; no intervention required
• C FTc 0.28 s indicates hypovolaemia/preload responsiveness; administer a fluid bolus ✓
• D FTc 0.28 s indicates left ventricular outflow obstruction; reduce afterload

Explanation

Corrected flow time (FTc) on oesophageal Doppler represents systole duration corrected for heart rate. Normal FTc is 0.35–0.40 seconds. An FTc below 0.35 seconds, particularly below 0.33 s, indicates reduced LV filling time consistent with hypovolaemia or preload insufficiency. A positive response to passive leg raising (or a short fluid bolus) in this context confirms preload responsiveness, and a 250 mL crystalloid or colloid bolus should be given. FTc above 0.40 seconds with low peak velocity may indicate vasodilation. FTc is a well-validated, minimally invasive guide to intraoperative goal-directed fluid therapy.

Reference: Morgan & Mikhail's Clinical Anesthesiology, 6th ed.

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Written and medically reviewed by the StethoPrep medical team.