VALIDITY OF PULSE CONTOUR METHOD FOR CALCULATING CARDIAC OUTPUT OF THE DOG, WITH NOTES ON EFFECT OF VARIOUS ANESTHETICS

Abstract

A somewhat modified procedure is given for the calculation of the stroke index of the dog from the contour of the aortic pressure pulse. The quantitative validity of the method has been tested by 187 simultaneous comparisons with the dye injn. or the direct Fick technics. The avg. error is + 10.1%, and there is no evidence of a systematic error in the contour calculation. Expts. designed to produce tone changes in the arterial bed did not produce significant change in the accord of the calculated with measured stroke index. It is concluded that the contour method is reasonably accurate within a mean pressure range of 23-300 mm. Hg. The basal cardiac index and resistance values of the dog are largely dependent on the anesthesia employed. Ether seemingly acts as an effective vasodilator, with a resulting large cardiac index, low resistance and moderately low arterial pressure values. Barbiturates, in full anesthetic doses, tend to produce elevated arterial pressure, low cardiac index and high resistance values.