Comparison of direct blood pressure measurement at the radial and dorsalis pedis arteries during surgery in the horizontal and reverse Trendelenburg positions.

The differences in simultaneous arterial pressure measurements from the radial and dorsalis pedis arteries were studied in anaesthetised adult patients in either the horizontal or reverse Trendelenburg position. Significantly higher pressures were measured from the dorsalis pedis artery than from the radial artery in both positions, even allowing for the hydrostatic effect on the dorsalis pedis arterial pressure in the non-horizontal group. If the dorsalis pedis artery is to be used to measure direct arterial blood pressure, we recommend that readings be compared with an arm sphygmomanometer to avoid potentially dangerous hypotension being missed.