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Femoral artery catheterisation for cardiac output measurement using the femoral artery thermodilution technique does not compromise limb perfusion


Measurement of cardiac output and extra-vascular lung water in patients with Acute Respiratory Distress Syndrome receiving vasopressors involves femoral artery catheterisation through a 4.5-Fr sheath, with potential risk of vascular compromise to the limb. Scanning laser Doppler flowmetry is a new non-invasive technique for assessing tissue blood flow, making up to 250 point measurements of perfusion per second as a laser is scanned over a surface, creating a grey scale photographic and a colour perfusion. We have used this technique to assess pedal skin perfusion following Femoral artery catheterisation in addition to standard clinical evaluation.


10 intubated, ventilated and sedated patients without clinical evidence of peripheral arterial disease were randomised to right or left leg catheterisation (Pulsiocath 2024L, Pulsion, Munich, Germany). 9 were receiving vasopressors (Noradrenaline 0.03–0.48 μg/kg/min, Adrenaline 0.09–0.8 μg/kg per min). Room temperature was constant and both legs were uncovered for 15 min equilibration. Measurements were made before and after insertion, and at 24 h. Laser Doppler scans (Moor LDI, Moor Instruments Ltd, Axminster, Devon, UK) of the plantar aspect of the feet, and systemic mean arterial and maximum calf occlusion pressures were recorded. The sole of the foot was outlined from the photographic image, allowing calculation of mean perfusion units (PUs) from the corresponding perfusion image (>17 000 individual perfusion measurements).


Mean systemic and occlusion pressures, and skin perfusion were unchanged between legs, and between measurement time points, following insertion of the catheters. Mean biases prior to, immediately after and 24 h following catheterisation were 12.46, 16.35 and 2,85 PUs (95% confidence intervals -36.2 to 61.1, -17.9 to 50.6 and -48.7 to 54.4 PUs) respectively. The limits of agreement were -132.5 to 157.4, -85.3 to 119 and 156.7 to 151 PUs.


Femoral artery catheterisation for double-indicator dilution measurements does not reduce calf occlusion pressures or foot skin perfusion in patients receiving vasopressor drugs. Scanning laser Doppler flowmetry is easily used to assess changes in foot perfusion and the effect of interventions that may reduce blood flow to the skin of the foot.


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Boyle, N., Ng, B., Berkenstadt, H. et al. Femoral artery catheterisation for cardiac output measurement using the femoral artery thermodilution technique does not compromise limb perfusion. Crit Care 2 (Suppl 1), P078 (1998).

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