FetalAssessmentNotes - Chapter 14: Intrapartum Fetal...

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Chapter 14: Intrapartum Fetal Surveillance I. Identify the standards of care related to fetal heart rate (FHR) monitoring. A. Source of standards 1. American College of Obstetricians and Gynecologists (ACOG) 2. American Academy of Pediatrics (AAP) 3. Association of Women’s Health, Obstetric, and Neonatal Nursing (AWHONN) B. Guidelines (Table 14-2, p. 368) II. Discuss the four parameters used to describe uterine contractions A. Cycle 1. Increment – period of increasing strength of uterine contraction 2. Peak (acme) – period of greatest strength of a uterine contraction 3. Decrement – period of decreasing strength of a uterine contraction B. Characteristics 1. Frequency – period from the beginning of one contraction to the beginning of the next contraction 2. Intensity – strength of a uterine contraction 3. Duration – period of a uterine contraction from beginning to end 4. Interval – period from the end of one contraction to the beginning of the next contraction 5. Resting tone – degree of uterine muscle tension when the woman is not in labor or between contractions III. Fetal Oxygenation A. Adequate fetal oxygenation needs five related factors 1. Normal maternal blood flow and volume to the placenta 2. Normal Oxygen saturation in the maternal blood 3. Adequate exchange of O 2 and CO 2 in the placenta 4. An open circulatory path from the placenta to the fetus through the umbilical cord 5. Normal fetal circulatory and oxygen-carrying function B. Uteroplacental exchange 1. Spiral arteries deliver maternal blood to the placenta (Ch 6, Figure 6-7, p. 100) 2. The mothers blood leaves the spiral arteries and enters the intervillous spaces in the placenta, bathing the fetal chorionic villi containing the fetal vessels 3. Oxygen and nutrients in the maternal blood in the intervillous spaces pass across the membranes of each villus into the fetal circulation 4. Carbon dioxide and other fetal wastes pass across the membranes of the villi from the fetal blood to maternal the maternal blood 5. The maternal blood, carrying the fetal wastes, is drained from the intervillous spaces by endometrial veins, returning to maternal circulation for excretion 6. There is no mixing of fetal and maternal blood 7. Uterine contractions during labor compress the spiral arteries a. Maternal blood flow into the intervillous spaces is temporarily stopped b. The fetus must rely on the oxygen supply already in its body and in the intervillous spaces c. This reserve is enough for about 1-2 min d. Oxygenated maternal blood re-enters the intervillous spaces when the contraction ends C. Fetal circulation (Ch 6, Fig 6-9, p. 104; Fig 6-10, p. 105) 1. One umbilical vein carries oxygenated blood to fetus 2. Two umbilical arteries carry deoxygenated blood to placenta D. Regulation of fetal heart rate (FHR) 1. Autonomic nervous system a. Balance between sympathetic and parasympathetic systems required – achieved by the hypothalamus b. Sympathetic stimulation i. Increases FHR
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This note was uploaded on 04/24/2008 for the course NURS 230 taught by Professor Knobloch during the Spring '08 term at Lady of the Lake.

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FetalAssessmentNotes - Chapter 14: Intrapartum Fetal...

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