Ch 13 lecture notes Comprehensive Guide to Intrapartum Fetal Heart Rate and Uterine Contraction Monitoring

Fetal Heart Rate Monitoring Methods and Protocols

• Intermittent Auscultation and Monitoring     * Application: Used for laboring mothers based on the stage of labor, presence of complications, and nature of interventions.     * Criteria for Intermittent Use: Appropriate for uncomplicated pregnancies where no Oxytocin (Pitocin) is being administered and the cervix is approximately $5\,\text{cm}$ dilated.     * Procedure Cycle: The patient is hooked to the monitor for $20\,\text{min}$, allowed to ambulate for $1\,\text{hour}$, and then re-monitored for another $20\,\text{min}$. This cycle repeats until the active stage of labor begins or specific interventions are required.

• Continuous Monitoring     * Indications: Required if membranes are ruptured (A_ROM or S_ROM), if Oxytocin is being administered, or if other interventions are in place.     * Rationale: The fetus can decompensate quickly under these conditions; continuous tracking allows for rapid medical response even when the patient is ambulating.

Device Placement and Fetal Positioning

• Vertex (Cephalic) Presentation     * Definition: The fetus is in a head-down position (Vertex or Cephalic).     * Placement: Monitors are placed low on the maternal abdomen to target the fetal upper back.

• Breech Presentation     * Definition: The fetus is positioned with the head up and buttocks or feet down.     * Placement: Monitors are placed high on the maternal abdomen, specifically above the umbilicus, to reach the fetal upper back.

• Leopold Maneuver     * Purpose: A palpation technique used to determine fetal lie, presentation, and position inside the uterus.     * Technique: Palpating the abdomen to distinguish between "smooth" textures (the fetal back) and "bumpy" textures (the fetal limbs).     * Assessing Neck Flexion: Palpating the sides determines if the fetal neck is flexed (rounded) or extended (prominent).     * Clinical Importance: The maneuver must be performed before monitor placement because fetal heart rate monitors 3function most effectively when placed over the fetal back.

Monitoring and Charting Frequencies

• Latent Phase of Labor     * Definition: Typically defined as the period up to $4\,\text{cm}$ of cervical dilation (though some hospital policies define active labor as starting at $6\,\text{cm}$).     * Frequency: Auscultate and chart every $30$ to $60\,\text{min}$.

• Active Phase of Labor     * Definition: Typically defined as cervical dilation past $6\,\text{cm}$.     * Frequency: Auscultate and chart every $15$ to $30\,\text{min}$.

• Second Stage of Labor     * Definition: The period from $10\,\text{cm}$ dilation (complete) until fetal expulsion (pushing).     * Frequency: Auscultate every $5$ to $15\,\text{min}$.     * Charting: Documentation is required every $5\,\text{min}$ during the entire pushing phase, which may be done retroactively if simultaneous intervention and charting are not possible.

• Key Priorities for Fetal Heart Rate (FHR) Assessment     * Post-Rupture of Membranes (ROM): FHR must be checked immediately after Artificial Rupture of Membranes (AROM) or Spontaneous Rupture of Membranes (SROM) to screen for cord prolapse (where the cord precedes the baby), which can cause fetal bradycardia.     * Medications and Procedures: FHR assessment is required before and after medication administration, procedures, or ambulation.     * Medication Effects: Stadol and Nubain can cause minimal variability or bradycardia. Epidurals can cause fetal bradycardia secondary to maternal hypotension.

Uterine Contraction Assessment

• Assessing Intensity/Strength     * External Monitoring (Toco): Standard external monitors cannot accurately determine the strength of a contraction.     * Palpation Method: If no internal monitor is present, nurses must palpate the fundus:         * Mild Contractions: Feel like the tip of the nose.         * Moderate Contractions: Feel like the chin.         * Strong Contractions: Feel like the forehead.     * Internal Monitoring (IUPC): The Intrauterine Pressure Catheter (IUPC) provides an objective measurement of pressure in Montevideo Units (MVUs).     * Montevideo Units (MVU): A measurement of the total pressure inside the uterus during a $10\,\text{min}$ window. A total of at least $200\,\text{MVU}$ is typically required for adequate labor progression.

• Duration and Frequency Calculation     * Duration: The time from the start of one contraction to its end, documented as a range (shortest to longest) in a $10\,\text{min}$ window (e.g., $30-60\,\text{sec}$).     * Frequency: The time from the start of one contraction to the start of the next contraction, documented as a range of minutes (e.g., $2.5-3\,\text{min}$).     * Reading the Monitor Strip:         * Each red vertical line represents $1\,\text{min}$.         * The small boxes within the lines each represent $10\,\text{sec}$.         * Frequency is measured in whole and half units (e.g., $2, 2.5, 3, 3.5\,\text{min}$).         * Typical Goal: Contractions occurring every $2$ to $3\,\text{min}$, lasting approximately $60\,\text{sec}$.

• Abnormal Contraction Patterns     * Tachysystole (Hyperstimulation): Defined as more than $5$ contractions in a $10\,\text{min}$ window.     * Impact: Frequent contractions limit blood flow and oxygen to the fetus.     * Treatment: May require medications such as Terbutaline.

Fetal Heart Rate (FHR) Analysis

• Baseline Fetal Heart Rate     * Normal Range: $110-160\,\text{bpm}$.     * Calculation: Determining the mean rate, rounded to the nearest $5\,\text{bpm}$, during a stable period. There must be at least $2\,\text{min}$ of baseline in a given strip.     * Fetal Tachycardia (> 160\,\text{bpm}): Often caused by fetal anomalies, fetal anemia, maternal infection (Chorioamnionitis), maternal fever, or drug use (e.g., cocaine).     * Fetal Bradycardia (< 110\,\text{bpm}): Often caused by uteroplacental insufficiency, medications, heart blocks, or a prolapsed umbilical cord.

• Accelerations     * Definition for $\ge 32$ Weeks Gestation: An increase of at least $15\,\text{bpm}$ above baseline lasting for at least $15\,\text{sec}$ (the $15 \times 15$ rule).     * Definition for < 32 Weeks Gestation: An increase of at least $10\,\text{bpm}$ above baseline lasting for at least $10\,\text{sec}$ (the $10 \times 10$ rule).     * Clinical Significance: Accelerations rule out fetal hypoxia and indicate good oxygenation.

• Variability     * Definition: The fluctuations or "squigginess" in the baseline FHR, which indicate fetal oxygenation.     * Absent: Amplitude is undetectable or immeasurable; resembles asystole in appearance. Indicates potential hypoxia.     * Minimal: Amplitude of $1$ to $5\,\text{bpm}$. Can be caused by fetal sleep cycles (typically lasting $30\,\text{min}$) or maternal medications (Stadol, Nubain, or Epidural).     * Moderate: Amplitude of $6$ to $25\,\text{bpm}$. This is the reassuring goal indicating a well-oxygenated fetus.     * Marked: Amplitude > 26\,\text{bpm}. May appear like artifact; often indicates fetal distress or hypoxia.

Decelerations and Interventions (VEAL CHOP MINE)

• Early Decelerations (E - H - I)     * Pattern: The nadir (lowest point) of the deceleration matches the peak of the contraction ("on time").     * Cause: Head Compression (H).     * Intervention: Investigate (I). Check cervical status to see if the patient is nearing delivery or if the pelvis is too small.

• Variable Decelerations (V - C - M)     * Pattern: Abrupt drop in FHR (at least $15\,\text{bpm}$ for $15\,\text{sec}$), often shaped like a "V," "U," or "W."     * Cause: Cord Compression (C).     * Intervention: Move (M) the mother (side-to-side, knee-chest) to relieve pressure on the umbilical cord.

• Late Decelerations (L - P - E)     * Pattern: Gradual deceleration that begins after the peak of the contraction.     * Cause: Uteroplacental Insufficiency (P).     * Intervention: Execute (E) Evasive Maneuvers in order:         1. Move the mother to her side (reposition).         2. Administer a fluid bolus.         3. Turn off Oxytocin (Pitocin).         4. Administer Oxygen (though some research questions its effectiveness, it remains in standard protocols).         5. Consider C-section if unresolved.

• Accelerations (A - O - N)     * Cause: Oxygenation (O).     * Intervention: Nothing (N) (No intervention needed).

• Sinusoidal Pattern     * Appearance: A smooth, oscillating wave-like pattern with no variability.     * Significance: Extremely ominous. Associated with fetal anemia, maternal hemorrhage, or infection (Parvovirus). Indicates severe fetal distress/hypoxia; requires immediate delivery.

FHR Tracing Categories

• Category I (Normal/Reassuring)     * Baseline: $110-160\,\text{bpm}$.     * Variability: Moderate.     * Accelerations: Present or absent.     * Decelerations: No late or variable decelerations; early decelerations may be present.

• Category III (Abnormal/Non-reassuring)     * Criteria: Must have absent variability plus recurrent late decelerations, recurrent variable decelerations, or a sinusoidal pattern.

• Category II (Indeterminate)     * Definition: The "dumping ground" for any strip that is not perfectly reassuring (Cat I) and not critically abnormal (Cat III). Examples include minimal variability or moderate variability with recurrent lates.

Internal Fetal Monitoring

• Fetal Scalp Electrode (FSE)     * Procedure: A small screw-like wire is attached directly to the fetal scalp skin (avoiding fontanels and suture lines).     * Prerequisites: Maternal membranes must be ruptured. Nurses can insert it after rupture; providers can insert it to cause rupture.     * Indications: Obese patients, difficult fetal positioning, or whenever an external monitor cannot maintain a consistent tracing.     * Contraindications: Maternal blood-borne illnesses (HIV, Hepatitis B) due to the risk of transmission through the scalp puncture.     * Risks: Small risk of fetal infection or localized trauma.

• Intrauterine Pressure Catheter (IUPC)     * Function: Measures contraction strength (MVUs) and can be used for amnioinfusion (infusing fluid back into the uterus to cushion the cord and resolve variable decelerations).

• Nursing Role in Internal Monitoring     * Equipment: Ensure functionality and clear artifact.     * Technique: Use sterile gloves and sterile technique during insertion.     * Positioning: Use a wedge to prevent supine hypotension (compression of the vena cava by the heavy uterus), which decreases blood flow and causes late decelerations or bradycardia.

Questions & Discussion

• Question: If fetal heart tones are best heard above the umbilicus, what does this indicate regarding presentation?

• Response: The baby is in the breech presentation.

• Question: What is the first action for a client on Oxytocin who develops recurrent late decelerations?

• Response: Place the client in a side-lying position (Move mom).

• Question: What is the cause of variable decelerations?

• Response: Cord compression.