Scanning laser Doppler is a useful technique to assess foot cutaneous perfusion during femoral artery cannulation

There were no significant changes in mean occlusion pressures or in cutaneous perfusion between either leg or between measurement time points, immediately after or 24 h following insertion of the catheters.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. Femoral artery catheterization for double-indicator dilution measurements does not reduce calf occlusion pressures or foot skin perfusion in patients receiving vasopressor drugs.Fluid restriction and diuresis are frequently used in the management of the acute respiratory distress syndrome (ARDS), and a strategy of reduction in extravascular lung water (EVLW) has been shown to reduce both ventilator and intensive care unit (ICU) days [1].Intrathoracic blood volume (ITBV) comprises the left and right heart blood volumes and the pulmonary blood volume, and has been shown to be a better indicator of cardiac filling than the pulmonary artery occlusion pressure (PAOP) [2]. Both EVLW and ITBV are measured using double-indicator dilution and the COLD Z-021 system (Pulsion Medical Systems, Munich, Germany) which requires the insertion of a catheter into the femoral artery through a 4.5 F sheath. The technique also measures cardiac output by analysis of the femoral artery thermodilution curve. Digital ischaemia, although rare, is a well known complication of arterial cannulation [3,4,5] and this problem may be exacerbated in patients with sepsis who have microcirculatory disturbances including slowing of capillary blood flow and local arteriolar constriction [6], and who also often require vasopressors for hypotension. A clinical concern exists, therefore, about the safety of femoral artery cannulation in the critically ill patients who may potentially benefit from this sophisticated monitoring.Following insertion of the femoral artery catheter, peripheral tissue perfusion is usually assessed by regular clini