FHR & Uterine Contraction Monitoring PDF

Fetal Heart Rate and Uterine Activity Monitoring and Assessment  FHR and Uterine Activity Assessment Fetal response Oxygen supply must be maintained to prevent fetal compromise Decrease in oxygen supply due to: Reduction of blood flow through maternal...

Fetal Heart Rate and Uterine Activity Monitoring and Assessment  FHR and Uterine Activity Assessment Fetal response Oxygen supply must be maintained to prevent fetal compromise Decrease in oxygen supply due to: Reduction of blood flow through maternal vessels Reduction in oxygen content in maternal blood Alterations in fetal circulation Reduction in blood flow to intervillous space in placenta The goals of intrapartum FHR monitoring are to identify and differentiate the normal (reassuring) patterns from the abnormal (nonreassuring) patterns, which can be indicative of fetal compromise The oxygenation process has 3 components: The mother The placenta and intervillous space The fetus The changes to maternal physiology allow the pregnant woman to supply the fetus with oxygen and necessary nutrients. During the intrapartum period, a primary concern is ensuring adequate fetal oxygenation. The mother The fetus depends on the delivery of oxygenated blood in order to meet its metabolic needs and to withstand the stress associated with uterine contractions and labor. The mother is the only source of oxygen and other nutrients for the developing fetus. It is critical that the mother delivers sufficient oxygen to the placenta, where it can be picked up by the fetal blood system. The  Maternal Factors Several factors determine maternal oxygen delivery. Maternal blood plasma and cardiac output increase, thereby elevating flow to the placenta as the pregnancy progresses. The amount of oxygen in the mother's blood, which is determine by hemoglobin concentration and oxygen saturation The maternal pulmonary system undergoes physiological adaptions creating a greater capacity for oxygen transport that ultimately facilitates oxygen-carbon dioxide exchange in the placental bed and places the mother in a state of chronic compensated respiratory alkalemia  Blood Flow Alteration in maternal blood flow is another factor determining uteroplacental perfusion. At term, between 500-800 ml of blood should flow to the uterus per minute. Of this blood 70-90% is directed to the placenta Blue line- Fetal heart rate Green line- maternal heart rate Purple line- uterine contractions FHR and Uterine Activity Assessment Equipment Introduction ○ FHR Monitor ○ External US ○ Toco ○ Doppler ○ Wireless monitors ○ FSE ○ IUPC FHR and Uterine Activity Assessment Fetal Heart Rate ○ Methods of monitoring External (Noninvasive) Doppler (5 contractions in 10 minute averaged over a 30-minute window Fetal Heart Rate Baseline Variability Accelerations ○ /= 32 weeks 15 bpm x 15 sec Decelerations ○ Recurrent vs. intermittent Fetal monitor tracing Fetal Heart Rate Baseline  Fetal Tachycardia and Bradycardia Tachycardia Bradycardia Definition FHR >160 beats/min lasting >10 min FHR 10 min Possible Causes Interruption of fetal oxygenation, resulting in metabolic Atrioventricular dissociation (heart block) acidemia Fetal cardiac arrhythmias Structural defects Maternal fever Viral infections (e.g., cytomegalovirus) Infection (including chorioamnionitis) Medications Parasympatholytic drugs (e.g., atropine, hydroxyzine) Fetal heart failure Beta-sympathomimetic drugs (e.g., terbutaline) Maternal hypoglycemia Maternal hyperthyroidism Maternal hypothermia Fetal anemia Interruption of fetal oxygenation Drugs (e.g., caffeine, cocaine, methamphetamines) FHR and Uterine Activity Assessment Equipment introduction ○ Contraindications to invasive monitoring FSE Blood borne disease of mother Maternal/Fetal Hemophilia Placenta Previa Fetal malpresentation Nurse convenience The fetal central nervous system Sympathetic System Sympathetic impulses are generated in the fetal brainstem and are carried throughout the sympathetic fibers to the heart These act to increase the FHR, increase the strength of the myocardial contraction of the heart, and increase the fetal cardiac output The sympathetic stimulation influences FHR variability The sympathetic branch of the autonomic nervous system is present very early in fetal development. Parasympathetic System Parasympathetic impulses also originate in the fetal brain stem and are carried along the vagus nerve to the fetal heart. When stimulated, the vagus nerve causes an increase in fetal blood pressure, a decrease firing rate at the SA node, and thus a decrease in FHR  Variability Moderate- 6-25 bpm Minimal- greater than undetectable but less than or equal to 5 bpm Absent- undetectable Marked- greater than 25 bpm Absent Variability Minimal Variability Moderate Variability Marked Variability Sinusoidal Pattern Accelerations in FHR Fetal Heart Rate Decelerations Variable Deceleration Variable deceleration of the FHR is defined as a visually abrupt (onset to lowest point 30 seconds) decrease in and return to baseline FHR associated with Ucs. The deceleration begins after the contraction has started, and the lowest point of the deceleration occurs after the peak of the contraction. The deceleration usually does not return to baseline until after the contraction ends Late Decelerations Placental Insufficiency Fetal Heart Rate Decelerations Prolonged deceleration A prolonged deceleration is a visually apparent decrease (may be either gradual or abrupt) in FHR of at least 15 beats/min below the baseline Lasting more than 2 minutes but less than 10 minutes. A deceleration lasting more than 10 minutes is considered a baseline change. Prolonged Deceleration Fetal Heart Rate Mnemonic V Variable C Cord Compression E Early H Head Compression A Acceleration O Okay L Late P Placental Insufficiency Fetal Heart Rate Decelerations Interventions ○ Position Change ○ Decrease or discontinue augmentation medications ○ IV Fluid Bolus ○ Amnioinfusion- for variables Interventions Position change  Interventions for Specific Problems Maternal hypotension Increase rate of primary IV infusion. Change to lateral or Trendelenburg position. Administer ephedrine or phenylephrine if other measures are unsuccessful in increasing blood pressure. Uterine tachysystole Reduce or discontinue dose of any uterine stimulants in use (e.g., oxytocin [Pitocin]). Administer uterine relaxant (tocolytic) (e.g., terbutaline [Brethine]). Abnormal FHR pattern during second stage of labor Use open-glottis pushing if preferred by the woman. Use fewer pushing efforts during each contraction. Make individual pushing efforts shorter. Push only with every other or every third contraction.