BASIC ELECTRONIC FETAL HEART MONITORING

Electronic Fetal Heart Monitoring

What Does Fetal Monitoring Tell Us? Fetal oxygenation Acid-base status of the fetus Ability of the CNS to regulate FHR Why monitor? Prevention of hypoxia/asphyxia

Fetal Circulation https://www.youtube.com/watch?v=-IRkisEtzsk

Fetal Oxygen Supply Affected by: Maternal hyper/hypotension, hypovolemia Maternal Cellular Oxygen content (anemia) Alterations in fetal circulation Decreased Blood flow to Intravillous space (damage vasculature from disease process)

Consequences of Uterine Hypoxia/Asphyxia Cerebral Palsy Mental Retardation Epilepsy RDS Renal Damage NEC (Necrotizing Enterocolitis) Chronic Brain Impairment

External Monitoring: Device Placement Top device is the toco transducer which senses uterine activity The ultra sound device is lower and senses the fetal heart beat

Device Placement

Ultrasound Device Remember….only the round ultrasound transducer which detects the heart beat gets the ultrasound jelly

Internal Monitoring: Internal Devices

Fetal Scalp Electrode (FSE)

External vs. Internal Monitoring

External vs. Internal Devices Monitoring Fetal Heart Rate Monitoring Contractions External: Ultrasound device Internal: Fetal scalp electrode (FSE) External: Toco transducer Internal: Intrauterine pressure catheter (IUPC)

Remember….. The intensity of contractions can only be measured objectively with an IUPC in place Without it, the nurse must assess the strength of the contraction subjectively by palpating the fundus during a contraction If the fundus tone feels like: Tip of the nose=mild contraction Chin=moderate contraction Forehead=strong contraction

Fetal Heart Monitoring Top tracing represents fetal heart rate Bottom tracing represents contractions

Counting Contractions Duration: From the beginning to the end of one contraction (length of contraction) Frequency: Beginning of one contraction to the beginning of the next contraction

Uterine Perfusion During Contractions

Three Important Components of the Fetal Heart Monitor Strip 1) Baseline Heart Rate Is it normal, bradycardia, tachycardia? 2) Variability Minimal/Moderate/Marked 3) Periodic Changes 1) Accelerations (increases in fetal HR) 2) Decelerations: (decreases in fetal HR) I) Early Decels (Benign) II) Late Decels (Ominous) III) Variable Decels (Ominous)

Basic Pattern Recognition Baseline FHR: 110-160 for 10 min. Tachycardia: FHR> 160 for >10 min. Bradycardia: FHR<110 for > 10 min.

Bradycardia

Tachycardia Most common cause of tachycardia is maternal infection

Variability The “squiggliness” of the FHR tracing Baseline variability is a measure of the interplay (the push-pull effect) between the sympathetic and parasympathetic nervous systems Lack of variability is ominous Variability is the best indicator of fetal well-being

Periodic Changes: Accelerations Transient increases above the FHR baseline Fetal movement Contractions Accelerations are positive/reassuring

Variability with Accelerations

Periodic Changes:1) Early Decelerations Gradual onset before peak of contraction Return to baseline before end of contraction Uniform shape; similar to one another Cause: Head compression which causes increased intracranical pressure and vagal nerve stimulation with an accompanying decrease in FHR May indicate cephalo-pelvic disproportion (CPD) Not associated with hypoxia or acidosis

Early Decelerations

Periodic Changes: 2) Variable Decelerations U, V, or W shaped; varied shape Variable in duration, timing, depth, not uniform Cause: Cord compression Interventions: Position change, vaginal exam to R/O prolapsed cord, stop oxytocin, anticipate amnioinfusion, notify MD

Variable Decelerations Note the U,V, W shaped decelerations in heart rate

Variable Decelerations

What is an Amnioinfusion? Effective for replacing diminished amniotic fluid levels which helps prevent cord compression

Periodic Changes: 3) Late Decelerations Decent of FHR begins after contraction Delayed onset. Also delayed return to fetal baseline HR after contraction ends. Therefore a late recovery Cause: Utero-placental insufficiency Interventions: Lateral positioning, stop oxytocin, oxygen, IV fluid bolus, notify MD, anticipate expedient delivery

How Maternal Positioning Affects Fetal Perfusion

Late Decelerations

Prolonged Deceleration

True Knot in the Cord What type of periodic change would you expect to see with this situation?

Categorizations of Intrapartum Fetal Heart Rate Patterns The National Institute of Child Health and Human Development has defined three categories of intrapartum FHR patterns: Category I: Normal Category II: Indeterminate Category III: Abnormal

Category I: Normal The fetal heart rate tracing shows ALL of the following: Baseline FHR 110-160 BPM, moderate FHR variability, accelerations may be present or absent, no late or variable decelerations, may have early decelerations Strongly predictive of normal acid-base status at the time of observation. Routine care

Category II: Indeterminate The fetal heart rate tracing shows ANY of the following Tachycardia, bradycardia without absent variability, minimal variability, absent variability without recurrent decelerations, marked variability, absence of accelerations after stimulation, recurrent variable decelerations with minimal or moderate variability, prolonged deceleration > 2minute but less than 10 minutes, recurrent late decelerations with moderate variability, variable decelerations with other characteristics such as slow return to baseline Not predictive of abnormal fetal acid-base status, but requires continued surveillance and re-evaluation

Category III: Abnormal The fetal heart rate tracing shows EITHER of the following: Sinusoidal pattern OR absent variability with recurrent late decelerations, recurrent variable decelerations, or bradycardia Predictive of abnormal fetal-acid base status at the time of observation. Depending on the clinical situation, efforts to expeditiously resolve the underlying cause of the abnormal fetal heart rate pattern should be made

Sinusoidal Fetal Heart Pattern A sinusoidal fetal FHR pattern is defined as a pattern of fixed, uniform fluxuations of the FHR that creates a pattern resembling successive geometric sine waves. Characterized by the absence of variability. Associated with increased perinatal morbidity and mortality and poor perinatal outcome.

Think “Veal Chop” V (Variable decel) E (Early decel) A (Accelerations) L (Late decels) = Cord compression = Head compression = OK = Placental insufficiency