STUDIES OF THE OXYGEN CONSUMPTION OF FRESH PLACENTAL TISSUE FROM NORMAL AND ABNORMAL PREGNANCIES

FOR many years it has been known that placental changes are closely associated with preeclampsia. Although opinions have vaned as to which is the primary disturbance, it is widely accepted at present that in patients suffering from pre-eclampsia there is a degree of placental ischaemia, which accelerates the normal process of ageing. This ischaemia, as well as being reflected in histological (Tenney and Parker, 1940) and histochemical changes (Wislocki and Dempsey, 1946), might also be associated with a change in the aerobic metabolism of the tissue. Although the results of several studies of the rate of oxygen consumption of placental tissue have been published during the last thirty years, from the early German investigations (e.g., Rech, 1924), using perfusion methods of estimation, to the more recent experiments of Page (1948), Hellman, Hams and Andrews (1950) and Villee (1953), only the more recent studies have included particular reference to the effects, if any, of pre-eclampsia. Relatively few cases have been investigated, and whereas Hellman, Harris and Andrews, and Villee showed no significant change from normal levels in severe, acute pre-eclampsia, Page observed a lower rate of oxygen consumption in cases of severe pre-eclampsia in which evidence of this complication had existed for some weeks. In this investigation we have made an endeavour to clarify these findings by studying a larger number of cases, not only of severe, acute pre-eclampsia, but also of less severe preeclampsia in which signs or symptoms had existed for some time. As relatively little data was available regarding the effect of other complications, such as essential hypertension and diabetes mellitus, on the rate of oxygen consumption of placental tissue, it was decided to extend this study to include a number of pregnancies with these complications. In addition, a number of twin pregnancies were investigated. As a basis for comparison of the results obtained in these cases, a group of clinically normal cases was studied to form a pattern for normal pregnancy. In this group particular attention was given to pregnancies which had continued beyond the expected date of delivery.