Fetal Assessment during Labor Nancy W. Vines, RN, BSN Graduate Student East Carolina University College of Nursing January, 2009

Objectives Discuss the various types of fetal monitoring Demonstrate application of external fetal monitor (EFM) Define terminology associated with fetal monitoring Determine fetal heart rate (FHR) baseline Identify common FHR patterns Describe and differentiate among nursing interventions used for managing specific fetal heart rate patterns

Indications for Fetal Monitoring Primary tool for assessment of fetal well-being Primary method of obtaining information about uterine activity

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Types of Intermittent Monitors

Intermittent Auscultation

External Monitoring Ultrasound (cardio) transducer Tocotransducer

Application of External Monitors Position mother Semi-fowler’s Lateral recumbent Wedged to one side Apply EFM belts snuggly Use “quarter size” amount of transducer gel

Transducers Cardio Transducer “Cardio” Ultrasonic transducer that picks up movement within the fetal heart Tocotransducer “Toco” Detects changes in the shape of the woman’s abdominal wall directly above her fundus—is pressure sensitive

Placement of Cardio Apply over fetal back Leopold’s Obesity Lateral position Breech Maternal pulse

Placement of Toco Palpate fundus Term—Place toco ABOVE umbilicus Preterm—Place toco BELOW umbilicus

Monitor Paper Moves 3cm per minute Divided into 2 sections: Top half records FHR Bottom half records uterine contractions

FHR graphs in this section in beats per minute Uterine Contractions graph in this section; the numbers in this section are not significant with an external monitor

Internal Monitoring Spiral electrode Intrauterine pressure catheter -IUPC

Uterine Tone The lowest intrauterine pressure between contractions is called resting tone Normal resting tone is 5-10 mmHg; during labor resting tone may rise to 10-15 mmHg Pressure during contractions rises to ~25-100 mmHg (varies with stage) A resting pressure above 20 mmHg causes decreased uterine perfusion

Uterine Tone Determined by palpation if external monitoring Montevideo units (MVUs) if internal Add peak pressures from all contractions in a 10 min period and subtract sum of baseline tones of the contractions – nl 180-250; more common practice today is to just add peak pressures from baseline in a 10 minute period

Review of Physiologic Basis for Monitoring Factors necessary for optimal fetal well-being: Intact, functional maternal physiology Intact, functional placenta Intact, functional fetus

Maternal Component Insufficient oxygen or nutrition in the mother can cause: Intrauterine growth restriction (IUGR) Fetal hypoxia Fetal metabolic acidosis Acute asphyxia Fetal death

Placental Component Inadequate placental function can cause insufficient oxygen and nutrient transfer to the fetus Placental function can be chronically impaired by: Maternal hypertension (pre-existing or PIH) Pre-eclampsia Diabetes mellitus (insulin dependent) Intrauterine infection Placental anomalies Decreased 02 content in maternal blood (smoking; asthma)

Placental Component Placental function during labor can be acutely impaired by: Placental separation abruptio placenta Sudden maternal hypotension Tachysystole of uterus Valsalva maneuver for pushing (holding breath decreases O2 to placenta)

Fetal Component Inadequate oxygen causes fetal hypoxemia Fetal hypoxemia causes tissue hypoxia Tissue hypoxia results in anaerobic metabolism Anaerobic metabolism causes production of lactic acid Lactic acid causes metabolic acidosis fetal death

Physiology of FHR Regulation FHR is dependent on fetal, maternal, uterine, and placental features designed to regulate blood flow and nutrient and gas exchange FHR regulated by: Sympathetic and parasympathetic nervous systems based on baroreceptor and chemoreceptor responses Central Nervous System

Physiology, continued Parasympathetic nervous system is a cardiodecelerator Sympathetic nervous system is a cardioaccelerator Baroreceptors –decrease fetal heart rate Chemoreceptors- increase fetal heart rate Central Nervous System Sleep state- decreases variability and reactivity Alert state- increases variability and reactivity

FHR and Uterine Activity

Fetal Monitoring Terminology 1997—Meeting in Washington, D.C. to develop list of terms used in interpreting fetal monitor strips—NICHD (National Institute of Child Health and Human Development Research Planning Workshop) Lay dormant for many years 2005—AWHONN and ACOG reviewed 1997 document and adopted it in 2005

Why Change to NICHD? Standardize and simplify key clinical terms and protocols Improve communication Promote patient safety Recommended by The Joint Commission in a July, 2004 Sentinel Event Alert (# 30) Make terminology consistent among professional organizations (AWHONN/ACOG)

5 Basic Components of a Fetal Heart Rate Tracing Baseline fetal heart rate Variability Accelerations Decelerations Changes or trends over time

FHR Baseline Baseline—FHR rounded to increments of 5 bpm, over a 10 minute period of time (not including accels, decels, and periods of marked variability) fetus is not under stress range is 110-160 bpm minimum baseline duration must be at least 2 minutes in the 10 minute segment reported as a single number, not a range

FHR Variability Variability—Normal irregularity (fluctuations) of cardiac rhythm due to continuous balancing interaction of the sympathetic and parasympathetic divisions of the fetal autonomic nervous systemIrregular fluctuations from baseline of 2 cycles per minute or more (in the absence of contractions, accelerations, decelerations) Measured from peak to trough of single cycle Measured in bpm Absence of variability can be a sign of fetal CNS depression and hypoxia

Variability

Causes of Decreased Variability Prematurity Narcotics, tranquilizers, barbituates, anesthetics, anticonvulsants, smoking Fetal hypoxia and acidosis Fetal sleep states (can last up to 40 minutes Fetal cardiac arrhythmias

Responses to Decreased Variability Interventions to enhance uterine blood flow Mom in left lateral position IV hydration 02 at 8-10 lpm per mask Communication Maternal assessments FHR pattern and fetal movement Actions Fetal response to actions

Accelerations Indicate fetal well-being when they occur with fetal movement Increase in FHR – may be with contractions or with other activities Can be periodic or episodic Abrupt (onset to peak <30 sec) increase Increase of 15 bpm, lasting 15 sec, return to baseline < 2 min

Accelerations

Decelerations Decelerations are changes in the FHR that are classified on: their SHAPE, and their TIMING in relationship to the contraction

Changes in FHR Periodic changes – occur with contractions Episodic changes (non periodic) – do not occur with contractions

Tachycardia Tachycardia >160 bpm for ≥10 min Causes – maternal fever, infection, fetal anemia, drugs, maternal anxiety; maternal hemorrhage Response – left lateral position; increase IV hydration; O2 at 8-10 lpm via face mask; notify MD; may need to decrease uterine activity; administer meds as ordered

Bradycardia Bradycardia <110 bpm for ≥10 min Causes – profound fetal hypoxia, epidural drugs, maternal hypotension, maternal substance abuse, cord compression, uterine tachysystole Response – left lateral position; increase IV hydration; O2 at 8-10 lpm via face mask; vaginal exam (why?); notify MD

Early Decelerations Early – associated with head compression during contractions Shape is uniform, symmetrical Usually begins at the onset of the contraction and resolves at the end of the contraction (periodic) Must be repetitive** Typically a mirror image of the corresponding contraction Rarely drops below 100 bpm Considered benign with usually no intervention needed (FHR returns to baseline as pressure on fetal head is released)

Early Deceleration

Intervention for Early Decelerations Vaginal exam for presentation, dilatation, and station Change maternal position Surveillance—document and continue to observe**

Variable Decelerations Variable- associated with cord compression A visually apparent abrupt decrease in FHR (<30 sec) Occurs at any time during or between the contraction (unrelated to timing of uc) (periodic or episodic) Often drops below 100 bpm Shape may be U, V, or W Return to baseline varies; may have rapid or prolonged return to baseline

Variable Decelerations Variables, continued Frequently observed with pushing Not necessarily repetitive Severe uncorrected variables are associated with fetal hypoxia, acidosis, and low apgars May be reassuring or non-reassuring- thus “variable!”

Variable Deceleration

Interventions for Variable Decelerations Change maternal position Notify attending physician If variables are severe: Discontinue Pitocin if infusing Administer oxygen at 8-10 lpm** Vaginal or speculum exam to assess for cord** Amnioinfusion** Termination of labor is severe variables are not correctable Decrease uterine activity (Terbutaline)

Amnioinfusion

Amnioinfusion

Late Decelerations Late- associated with uteroplacental insufficiency Shape is uniform and symmetrical a visually apparent, gradual decrease and return of the FHR associated with a uc Must be repetitive Rarely less than 100 bpm; lowest point after peak of uc Clinical significance: Omnious – Indicates decreased O2 available to fetus; hypoxia Intervention usually needed

Causes of Uteroplacental Insufficiency Pitocin causing uterine tachysystole (previously known as hyperstimulation) Maternal or supine hypotension Pre-eclampsia or eclampsia Post maturity Maternal diabetes Placenta previa / abruption

Late Deceleration

Interventions for Late Decelerations Change maternal position** (L side) Correct maternal hypotension Increase IV fluid rate or give bolus, especially if maternal hypotension or dehydration present** Discontinue pitocin if infusing** Administer O2 at 8-10 lpm by mask** Notify attending physician Terminate labor if pattern not correctable

Prolonged Decelerations Lasts for more than 2 minutes but less than 10 minutes Can be abrupt or gradual Usually >15 bpm below baseline Intervention needed

Review of Assessment and Management Reassuring and Non-reassuring FHR Patterns and Management

Reassuring Patterns Baseline Rate- 110-160 bpm No periodic changes No late decelerations No non-reassuring variable decelerations Moderate baseline variability Accelerations with fetal movement No concerning changes or trends over time

Non-reassuring Patterns Progressive > or < in baseline rate Tachycardia Severe bradycardia Absent or minimal variability Severe variable decelerations Repetitive or uncorrected late decelerations Prolonged deceleration One or more of the 5 FHR components is abnormal

Priorities- A-B-C-Ds of Intrapartum Fetal Monitoring A. Assess Oxygen Pathway Lungs Heart Vasculature Uterus Placenta Cord

Priorities- A-B-C-Ds of Intrapartum Fetal Monitoring B. Begin Corrective Measures Supplemental oxygen Maternal position changes IV fluid administration Correcting maternal BP Reducing uterine activity Alter 2nd stage pushing technique Amnioinfusion Re-evaluate

Priorities- A-B-C-Ds of Intrapartum Fetal Monitoring C. Clear Obstacles to Rapid Birth Plan ahead (i.e., call OR , check equipment, anesthesia, urinary catheter, tocolytics)

Priorities- A-B-C-Ds of Intrapartum Fetal Monitoring D. Decision to Birth Time - Decision to allow labor to continue or to proceed with delivery- need to weigh the benefit of vaginal birth against the risk of fetal metabolic acidemia – must be individualized

Other Methods of Fetal Assessment Fetal Scalp Sampling Scalp stimulation Acoustic stimulation Fetal pulse oximetry Umbilical cord acid base determination

Client Teaching Explanation of monitoring technique used Maternal position – not supine Don’t use valsalva maneuver for 2nd stage labor

Documentation Varies by institution – computer or hard copy chart, fetal monitor strip What should be documented – Maternal Assessments Fetal Assessment Monitor adjustments Interventions Evaluation

Review of Decelerations If you get to class EARLY—that’s good! If you get to class LATE—that’s bad! If you vary between early and late—that’s VARIABLE and can be good or bad depending on the situation! 

References Chauhan, S. P., & Macones, G. A. (2005). Intrapartum fetal heart rate monitoring. [ACOG Practice Bulletin]. The American College of Obstetricians and Gynecologists, 106(6), 1453-1461. Lowdermilk, D. L., & Perry, S. E. (2007). Maternity & Women’s Health Care. In C. Jackson & L. Gower (Eds., 9h ed.). Fetal Assessment during Labor (pp. 497-518). St. Louis: Mosby Elsevier. Macones, G. A., Hankins, G. D., Spong, C. Y., Hauth, J., & Moore, T. (2008). The 2008 national institute of child health and human development workshop report on electronic fetal monitoring: Update on definitions, interpretation, and research guidelines. [JOGNN Principles & Practice Bulletin]. Journal of Obstetric, Gynecologic & Neonatal Nursing, 37, 510-517.