A Simplified Thermistor Flowmeter and Thermometer

Artificial Placentae1

“…The present set-np shows that it is not due to the abscuce of cardiac pulsation or movements as has bcen suggested and one must think of some other cause. The difficultmy in establishing a permanent circulation in placenta --H" is certainly a,ri exaniple of the delicate adjustments now known to be necessary if it is proposed t o maintain physiological pressures, flow rates and blood volumes in any system involving an extra-corporeal circulation 15,8,9,10,IS]. We are at present studying these problems, The difficulties should not be insurmountable if i t is proposed to use a placenta of either type for short periods of time only as a resuscitation measure, but difficulties will have to be overcome before foetuses can be maintained in a physiological state for long periods of time.…”

“…Furthcrmore, changes in the flow rate could only be dctected daring a n experiment by counting the dots on the tracing, and after the cxperiment was over a considerable amount of work had to be done to make a continuous rccortl of the flow. A new flow meter based upon better principles has now been constructed and a description of it is in press [15].…”