Abstract
Cardiac output per minute was determined in these experiments by the principle of Fick. 1 In most instances blood for analysis was obtained by right and left ventricular puncture, (see Bancroft, Boycott, Dunn and Peters, 2 and Marshall. 3 ) In certain experiments, where chloroform was used, arterial blood was obtained from the femoral artery and venous blood through a cannula inserted into the right auricle through the external jugular vein, as suggested by Stewart 4 for experimental determination of cardiac output.
In all but two groups of experiments determinations were made on trained unanesthetized dogs. Homocamfin and ephedrine effects were also studied in dogs whose circulation had been altered by chloral and by chloroform. Blood pressure was determined by means of sphygmomanometer and stethoscope, except in the chloroform experiments, where the carotid artery as well as the trachea was opened.
Chloral Hydrate: Eight observations were made of the effect of toxic doses on normal dogs. In six of these the output was increased by 17 to 81 per cent (average 58), blood pressure decreased an average of 32 per cent, heart rate increased an average of 35 per cent, oxygen consumption remained practically unchanged. In two experiments the output decreased 6 and 53 per cent. For this we can offer no explanation, for in subsequent observations with the same dosage the same dogs showed an increase of 44 and 81 per cent in output. Average changes are plotted as Curve 1 in the chart.
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