Fetal monitoring with pulse oximetry.
Continuous fetal monitoring was achieved with a fetal scalp pulse oximetry sensor in 86 labours. The average recorded fetal oxygen saturation in early labour (cervical dilatation less than 5 cm) was 68% (SD 13%). At the end of labour (cervical dilatation greater than or equal to 9 cm) the recorded mean oxygen saturation was 58% (SD 17%). The largest range of readings during a single labour was 81%-11% but this drop was associated with cord compression. The average SD during 1 h of normal labour was 10%. A second group of 40 fetuses was monitored during induction of labour before and after elective amniotomy. Oxygen saturation did not appear to change after amniotomy (mean change -0.4%, SD 1.2%) and there was no difference between mean antenatal or early intrapartum readings. We excluded the amniochorionic membranes as a possible source of data corruption by measuring their in vitro absorption spectra and confirming that they do not preferentially absorb light of either 660 or 940 nm wavelength. Non-invasive pulse oximetry can be used to monitor the fetus before and during labour.
Johnson
N
N
Department of Obstetrics & Gynaecology, St James' University Hospital, Leeds.
Johnson
V A
VA
Fisher
J
J
Jobbings
B
B
Bannister
J
J
Lilford
R J
RJ
D000650:Amnion / Q000601:surgery; D005260:Female; D005312:Fetal Blood / Q000737:chemistry; D005323:Fetal Monitoring / Q000379:methods*; D006801:Humans; D007751:Labor, Induced; D010092:Oximetry / Q000295:instrumentation / Q000379:methods*; D010100:Oxygen / Q000097:blood; D011247:Pregnancy; D011295:Prenatal Care / Q000379:methods; D012535:Scalp
D010100:Oxygen