Abstract: A catheter and introducer sheath assembly is provided for measuring a flow rate in a conduit by dilution methods. The catheter is configured to engage the introducer sheath in a predetermined alignment, where an indicator is passed through a volume defined by an exterior of the catheter and an interior of the introducer sheath to be introduced into the flow to be measured. The determination of the indicator temperature is extrapolated or estimated from (i) an observed temperature curve of an indicator sensor on the catheter that records a substitution of warmed fluid in the sheath by the introduced indicator and (ii) a pre-examined, predetermined or identified thermal properties or characteristics of the sensor, the catheter, or the sensor and catheter. The determination of the flow rate in the conduit is estimated using (i) the area of the dilution bolus and (ii) the return to baseline of the dilution bolus.

Abstract: A catheter and introducer sheath assembly is provided for measuring a flow rate in a conduit by dilution methods. The catheter is configured to engage the introducer sheath in a predetermined alignment, where an indicator is passed through a volume defined by an exterior of the catheter and an interior of the introducer sheath to be introduced into the flow to be measured. The determination of the indicator temperature is extrapolated or estimated from (i) an observed temperature curve of an indicator sensor on the catheter that records a substitution of warmed fluid in the sheath by the introduced indicator and (ii) a pre-examined, predetermined or identified thermal properties or characteristics of the sensor, the catheter, or the sensor and catheter. The determination of the flow rate in the conduit is estimated using (i) the area of the dilution bolus and (ii) the return to baseline of the dilution bolus.