Maternity Nursing: Intrapartum Q 24
At 38 weeks gestation, a client is having late decelerations. The fetal pulse oximeter shows 75% to 85%. The nurse should:
A. Discontinue the catheter if the reading is not above 80%.
B. Discontinue the catheter if the reading does not go below 30%.
C. Advance the catheter until the reading is above 90% and continue monitoring.
D. Reposition the catheter, recheck the reading, and if it is 55%, keep monitoring.
Correct Answer: D. Reposition the catheter, recheck the reading, and if it is 55%, keep monitoring.
Adjusting the catheter would be indicated. Normal fetal pulse oximetry should be between 30% and 70%. 75% to 85% would indicate maternal readings. Fetal pulse oximetry measures how much oxygen the baby’s blood is carrying. It uses a probe that sits on the baby’s head whilst in the uterus and vagina during labor. The probe is said not to interfere with the woman’s mobility during labor.
Option A: This method has two potential advantages over conventional fetal heart rate monitoring: (i) it directly measures the proportion of hemoglobin that is carrying oxygen: thus, oxygenation, the primary variable underlying the tissue-damaging effects of hypoxia/ischemia is being monitored; and (ii) it relies on an established, safe, noninvasive, widely?used technology found in every modern intensive care unit and operating theatre.
Option B: A variety of fetal pulse oximetry sensors has been studied. These are placed during a vaginal examination to attach to the top of the fetal head by suction (Arikan 2000) or clip (Knitza 2004), lie against the fetal temple or cheek (Mallinckrodt 2000; Nellcor 2004), or to lie along the fetal back (Prothia 2014). The sensor remains in situ and fetal pulse oximetry values are recorded for approximately 81% of the monitoring time (East 1997).
Option C: A prospective observational study found a low pulse oximetry oxygen saturation < 30% for at least 10 minutes correlates highly with fetal acidosis in cases of nonreassuring fetal heart rate (Nonnenmacher 2010). A novel fetal phantom based on actual fetal parameters showed that the wireless oximeter was capable of identifying 4% and 2% changes in diameter between the diastolic and systolic point in arteries of over 0.2 and 0.4 mm inner diameter, respectively (Stubán 2009).