Monitoring of transcutaneous P_O2in the fetus and mother during normal labor

Abstract

Transcutaneous PO2 (tcPO2) measurement is a non-invasive method which gives continuous information about central PO2. The method has previously been testes primarily on newborns and adults, and reports on the applicability of the method on the fetus during labor are still scanty and restricted to case reports. This paper reports on a systematic study of intrapartum fetal and maternal tcPO2-monitoring. The material is comprised of 19 parturients, the majority being nulliparae. All fetal presentations were vertex. The tcPO2 recordings averaged one hour in duration (Tab. I). FHR was recorded simultaneously. In 12 cases the electrode was affixed with glue, and in 7 cases a suction device was used for fixation. The electrode was attached when the cervix was dilated 4 to 6 cm. The mean tcPO2 was 20 mm Hg in the beginning of the registration, and showed a small decline in level throughout labor reaching 14 mmHg at the end of the registration period (Fig. 5). These values are in good agreement with those found by other authors in previous investigations. In some of the present cases, very low tcPO2 values were recorded. The relevance of these low tcPO2 values is unclear, and it is impossible to determine to what extent these tracings have true physiological relevance versus might be due to technical factors.

Continuous Measurement of Scalp Tissue Oxygen Tension and Carotid Arterial Oxygen Tension in the Fetal Lamb

“…As shown by Huch et al (9) and others (10,11), the transcutaneous technique can be applied during labour. However, application of the transcutaneous oxygen electrode on the fetal scalp during labour is not a simple procedure.…”

Correspondence

“…Careful shaving of the application site, however, seems not to influence the recorded tcPO, level, since O'Connor and Hytten (1979) report the same tcPO, levels and conclusions after having used the shaving technique described by us (Lofgren and Jacobson, 1977 …”

“…In systematic studies we found that very low tcPO, levels were occasionally recorded (Lofgren and Jacobson, 1977). The relevance of those low tcPO, levels were at that time unclear and we could not determine to what extent they had true physiological relevance or might be due to technical factors.…”

“…The bleeding might also have influenced the diffusion distance thus yielding an unreliable recording. To avoid shaving, we selected fetuses with sparse hair (Lofgren and Jacobson, 1977), but in our later studies we have used a specially-built pair of scissors to cut the hair very short in the area of electrode application. We find this technique quite sufficient and non-traumatic.…”

Non-invasive continuous fetal transcutaneous pO 2 and pCO 2 monitoring during labor

“…O'CONNER et al [14] have named this phenomenon the "tonsure effect". Moreover, with development of a caput succedaneum, correlation coefficients between the transcutaneous blood were lowered for tcpO 2 (L FGREN, 1977) [9] and tcpCO 2 (SCHMIDT and SALING, 1985) [19], and as a result unreliable recordings were given. Our technique of applying the electrode with a vacuum gave 76% successful recordings, as good a result as in WEBER'S reports [26].…”