ACCURACY OF INDIRECT DETERMINATIONS OF BLOOD PRESSURE IN THE RAT; RELATION TO TEMPERATURE OF PLETHYSMOGRAPH AND WIDTH OF CUFF

Abstract

The accuracy and dependability of the indirect ple-thysmographic method of measuring systolic blood pressure in the rat can be greatly increased by omitting warming of the body and by substituting local warming of the plethysmograph and tail to temps. between 42[degree] and 44[degree]C. The indirectly detd. systolic pressures by means of a 10 mm. occluding cuff under these conditions agree very well with directly detd. systolic pressures measured simultaneously by the Hamilton manometer from the femoral artery. A significant gradient of mean pressure in the caudal artery has been demonstrated by a micro-injn. method. For this reason a 10 mm. occluding cuff applied as closely as possible to the base of the warmed tail of the rat is more accurate than a 40 mm. cuff similarly applied.