Maternity Ch. 18: Fetal Assessment during labor
bradycardia
- Baseline FHR fewer than 110 bpm for 10 minutes or longer o Rare - not related to fetal oxygenation o Distinguish with prolong deceleration - management is different
tachycardia
- Baseline FHR greater than 160 bpm for 10 minutes or longer Early sign of fetal hypoxemia • Especially with late decelerations and minimal/absent variability
decelerations
- Caused by dominance of PNS response - normal or abnormal o Early o Late o Variable o Prolonged
how are FHR and UAs displayed?
- FHR and UA displayed on monitor paper or computer screen o FHR in upper section o UA in lower section - Each small square = 10 seconds o Larger box = 6 small squares = 1 minute
what is variability of FHR?
- Irregular waves or fluctuations in the baseline FHR of two cycles per minute or greater o Characteristic of baseline - does NOT include accelerations or decelerations o Quantified in beats per minute o Measured from peak to trough of single cycle
advantages of internal fetal monitoring
- More accurate o Not interrupted by fetal movement of maternal size o Membranes must be ruptured o Cervix sufficiently dilated (2-3 cm) o Presenting part low enough to allow placement of spiral electrode or IUPC or both
accelerations
- Visually apparent abrupt (onset to peak less than 30 seconds) increase in FHR above baseline rate o Peak at least 15 bpm above baseline o Lasts 15 seconds or more o Return to baseline less than 2 minutes from beginning of acceleration Before 32 weeks: o Peak of 10 bpm or more above baseline o Duration of at least 10 seconds - Acceleration of FHR for more than 10 minutes → considered change in baseline - Periodic or episodic - Association with fetal movement or spontaneous o If NOT spontaneous - elicted by fetal scalp stimulation or vibroacoustic stimulation - Considered indication of fetal well being - NORMAL o Normal fetal acid base balance
checklist for fetal monitoring equipment: US transducer
1. Has ultrasound transmission gel been applied to the transducer? 2. Was the fetal heart rate (FHR) tested and noted on the monitor strip? 3. Was the FHR compared with the maternal pulse and noted? 4. Does a signal light flash or an audible beep occur with each heartbeat? 5. Is the belt secure and snug but comfortable for the laboring woman?
checklist for fetal monitoring equipment: spiral electrode
1. Is the connector attached firmly to the electrode pad (on the leg plate or abdomen)? 2. Is the spiral electrode attached to the presenting part of the fetus? 3. Is the inner surface of the electrode pad pre-gelled or covered with electrode gel? 4. Is the electrode pad properly secured to the woman's thigh or abdomen?
checklist for fetal monitoring equipment: internal catheter or strain gauge
1. Is the length line on the catheter visible at the introitus? 2. Is it noted on the monitor paper that a UA test or calibration was performed? 3. Has the monitor been set to zero according to the manufacturer's directions? 4. Is the intrauterine pressure catheter properly secured to the woman? 5. Is the baseline resting tone of the uterus documented?
checklist for fetal monitoring equipment: prep of monitor
1. Is the paper inserted correctly (if using paper)? 2. Are transducer cables plugged securely into the appropriate port on the monitor? 3. Is the paper speed set to 3 cm/minute? 4. Was the monitor date and time verified (when using electronic documentation)?
checklist for fetal monitoring equipment: tocotransducer
1. Is the tocotransducer firmly positioned at the site of the least maternal tissue? 2. Has it been applied without gel or paste? 3. Was the uterine activity (UA) baseline adjusted between contractions to print at the 20-mm Hg line? 4. Is the belt secure and snug but comfortable for the laboring woman?
how do you perform intermittent auscultation of FHR
1. Palpate maternal abdomen to identify fetal presentation and position. 2. Apply ultrasonic gel to device if using Doppler ultrasound. Place listening device over area of maximal intensity and clarity of fetal heart sounds to obtain clearest and loudest sound, which is easiest to count. This location is usually over the fetal back. If using fetoscope, firm pressure may be needed. 3. Count maternal radial pulse while listening to FHR to differentiate it from fetal rate. 4. Palpate abdomen for presence or absence of UA to count FHR between contractions. 5. Count FHR for 30 to 60 seconds after a uterine contraction to identify auscultated baseline rate and changes (increases or decreases) in it. 6. Auscultate FHR before, during, and after contraction to identify FHR during the contraction or as a response to the contraction and to assess for absence or presence of increases or decreases in FHR. 7. When distinct discrepancies in FHR are noted during listening periods, auscultate for longer period during, after, and between contractions to identify significant changes that may indicate need for another mode of FHR monitoring.
how long must you trace to determine baseline FHR?
10 minutes mean rate rounded to closes 5bpm interval
what is the average resting tone?
10 mmHg palpate as "soft"
what is the normal FHR?
110 - 160 preterms = higher
how much interpretable data must there be in a 10 minute period to establish FHR baseline?
2 minutes
MVUs should not exceed??
250 MVUs
how long should you auscultate for after a contraction?
30-60 seconds
how long is relaxation time in second stage?
45 seconds or more
what is the max frequency of contractions in the second stage?
5 contractions per 10 minutes
how long is relaxation time in first stage?
60 seconds or more
what is the peak of the strength of UC?
80 mmHg
duration of contractions should not exceed how long?
90 seconds usually 45-80
monica AN24
Abdominally obtained electronic impulses to monitor both UA and FHR Uses five electrodes placed on abdomen to monitor • ECG from maternal and fetal hearts • Electromyogram from uterine muscle
clinical significance of late decelerations
Abnormal pattern associated with fetal hypoxemia, acidemia, and low Apgar scores; considered ominous if persistent and uncorrected, especially when associated with absent or minimal baseline variability
three-tier fetal heart rate classification system: category III
Absent baseline variability and any of the following: • Recurrent late decelerations • Recurrent variable decelerations • Bradycardia Sinusoidal pattern
umbilical cord acid base determination
Assess immediate condition of newborn after birth • Adjunct to Apgar score - if abnormal/confusing FHR tracings Withdraw blood from both umbilical artery and vein • Tested for pH • PCO2 • PO2 • Base deficit or base excess Arteries = fetal condition Vein = placental function
responsibilities of nurse during FHR and UA patterns
Assessing FHR and UA patterns, implementing independent nursing interventions, documenting observations and actions according to the established standard of care, and reporting abnormal patterns to the primary care provider (e.g., physician, nurse-midwife)
baseline FHR
Average rate during a 10 minute segment that excludes • Periodic or episodic changes • Periods of marked variability • Segments of the baseline that differ by more than 25 beats/minute Must be at least 2 minutes of interpretable baseline data in a 10 minute segment of tracing in order to determine baseline FHR • After 1- minutes of tracing - approximate mean rate is rounded to closest 5 bpm interval • If FHR varies between 130 and 140 bpm over 10 minutes → rounded to 135 • Normal: 110 - 160 bpm • Preterm fetus = higher
resting time
Average resting tone during labor is 10 mm Hg; if using palpation, should palpate as "soft" (i.e., easily indented, no palpable resistance)
how does position help with fetal status?
Avoid supine position Maintain side lying position or semi-Fowler position with lateral tilt to uterus
bradycardia - clinical significance
Baseline bradycardia alone is not specifically related to fetal oxygenation. The clinical significance of bradycardia depends on the underlying cause and the accompanying FHR patterns, including variability, accelerations, or decelerations.
what are the three categories of fetal heart tracings?
Category I FHR: • Normal • Fetal acid base status normal • No specific action Category II FHR: • Indeterminate • All tracings not in category I or III • Require continued observation and evaluation Category III FHR: • Abnormal • Immediate evaluation and intervention required
three-tier fetal heart rate classification system: category I
Category I fetal heart rate (FHR) tracings include all of the following: • Baseline rate 110 to 160 beats/minute (bpm) • Baseline FHR variability: moderate • Late or variable decelerations: absent • Early decelerations: either present or absent • Accelerations: either present or absent
three-tier fetal heart rate classification system: category II
Category II FHR tracings include all FHR tracings not categorized as category I or category III. Examples of category II tracings include any of the following: Baseline rate • Bradycardia not accompanied by absent baseline variability • Tachycardia Baseline FHR variability • Minimal baseline variability • Absent baseline variability not accompanied by recurrent decelerations • Marked baseline variability Accelerations • No acceleration produced in response to fetal stimulation Periodic or episodic decelerations • Recurrent variable decelerations accompanied by minimal or moderate baseline variability • Prolonged decelerations (≥2 minutes but <10 minutes) • Recurrent late decelerations with moderate baseline variability • Variable decelerations with other characteristics, such as slow return to baseline, "overshoots" or "shoulders"
causes of prolonged decels
Caused when mechanisms for late/variable decels last for extended period (more than 2 minutes) • Maternal hypotension • Uterine tachysystole or rupture • Extreme placental insufficiency • Prolonged cord compression or prolapse
duration
Contraction duration remains fairly stable throughout first and second stages, ranging from 45-80 seconds, not generally exceeding 90 seconds
frequency
Contraction frequency overall generally ranges from two to five per 10 minutes during labor, with lower frequencies seen in first stage of labor and higher frequencies (up to five contractions in 10 minutes) seen during second stage of labor
tachycardia - nursing intervention
Dependent on cause; reduce maternal fever with antipyretics as ordered and cooling measures; oxygen at 10 L/minute by nonrebreather face mask may be of some value; carry out health care provider's orders based on alleviating cause
causes of late decels
Disruption of oxygen transfer from environment to fetus caused by the following: • Uterine tachysystole • Maternal supine hypotension • Epidural or spinal anesthesia • Placenta previa • Placental abruption • Hypertensive disorders • Postmaturity • Intrauterine growth restriction • Diabetes mellitus • Intraamniotic infection
evaluate tracings how often throughout labor?
Evaluated at least every 30 minutes during first stage; 15 minutes during second stage • In low risk women Risk factors → 15 minutes first stage; 5 minutes second stage
causes of early decels
Head compression resulting from the following: • Uterine contractions • Vaginal examination • Fundal pressure • Placement of internal mode of monitoring
amnioinfusion
Infusion of room temp isotonic fluid (NS or lactated ringer's) into uterine cavity if volume of amniotic fluid is low • Without amniotic fluid - cord easily compressed during contraction or fetal movement = decrease oxygen and blood flow • Relieve intermittent umbilical cord compression → variable decels and transient fetal hypoxemia • Oligohydramnios or anhydramnios (none)
what controls the FHR?
Intrinsic rhythmicity of fetal heart CNS Fetal autonomic NS
how does pushing help with fetal status?
Keep mouth and glottis open and let air escape from lungs during pushing process
intermittent auscultation
Listening to fetal heart sounds at periodic intervals to assess FHR o Pinard fetoscope o Doppler US o US stethoscope o DeLee-Hillis fetoscope
montevideo units (MVUs)
MVUs usually range from 100-250 in first stage; may rise to 300-400 in the second stage. Contraction intensities of 40 mm Hg or more and MVUs of 80-120 are generally sufficient to initiate spontaneous labor. MVUs are used only with internal monitoring of contractions.
external fetal monitoring - tocotransducer
Measures UA transabdominally Placed over fundus above umbilical with elastic belt UCs of fetal movements depress a pressure sensitive surface Measure and record frequency and duration - NOT intensity • Useful first stage - intact membranes or antepartum testing Unable detect if obese Not able detect if preterm pregnancy • Fundus might be below level of umbilicus • Use palpation as well to assess frequency and validate monitor tracing
what changes occur to UCs during amnioinfusion?
Monitor intensity and frequency of UCs • Recorded uterine resting tone appears higher than normal - resistance to outflow and turbulence at end of the catheter • Uterine resting tone should NOT exceed 40 mmHg
intrauterine pressure catheter
Monitors the frequency, duration, and intensity of contractions. The two types of IUPCs are a fluid-filled system and a solid catheter. Both measure intrauterine pressure at the catheter tip and convert the pressure into millimeters of mercury on the uterine activity panel of the strip chart. Both can be used only when membranes are ruptured and the cervix is sufficiently dilated during the intrapartum period.
clinical significance of accelerations
Normal pattern. Acceleration with fetal movement signifies fetal well-being representing fetal alertness or arousal states.
clinical significance of early decels
Normal pattern; not associated with fetal hypoxemia, acidemia, or low Apgar scores
fetal scalp blood sampling
Obtain sample of fetal scalp blood through dilated cervix after membranes ruptured Limited by factors: • Requirement for cervical dilation • Membrane rupture • Technical difficulty of procedure • Ned for repetive pH determinations • Uncertaintay regarding interpretation and application of results Seldom used in US
how is the US transducer placed?
Once area of max intensity of FHR located • Conductive gel applied and US transducer positioned over area with elastic belt
what balances the FHR?
PNS and SNS
tachycardia - clinical significance
Persistent tachycardia in absence of periodic changes does not appear serious in terms of neonatal outcome (especially true if tachycardia is associated with maternal fever); tachycardia is abnormal when associated with late decelerations, severe variable decelerations, or absent variability.
how is the tocotransducer placed?
Placed over fundus above umbilical with elastic belt
what are the two most important factors to help with fetal status?
Position: o Avoid supine position o Maintain side lying position or semi-Fowler position with lateral tilt to uterus Pushing o Keep mouth and glottis open and let air escape from lungs during pushing process
electronic fetal monitoring
Purpose: ongoing assessment of fetal oxygenation Analyzed for fetal hypoxic events and metabolic acidosis • Implement interventions in timely manner to prevent damage Two methods: External: • External transducers placed on maternal abdomen to assess FHR and UA Internal: • Spiral electrode applied to fetal presenting part to assess FHR • Intrauterine pressure catheter (IUPC) assess UA and uterine resting tone
external fetal monitoring - US transducer
Reflect high frequency sound waves off moving interface = fetal heart and valves Interfere with sound • Artifact by fetal movement • Maternal obesity • Occiput posterior position of fetus • Anterior attachment of placenta FHR printed on formatted paper - simultaneously displayed on screen Once area of max intensity of FHR located • Conductive gel applied and US transducer positioned over area with elastic belt
relaxation time
Relaxation time is commonly 60 seconds or more in first stage and 45 seconds or more in second stage
nursing interventions of late decels
The usual priority is as follows: 1. Change maternal position (lateral). 2. Correct maternal hypotension by elevating legs. 3. Increase rate of maintenance IV solution. 4. Palpate uterus to assess for tachysystole. 5. Discontinue oxytocin if infusing. 6. Administer oxygen at 8 to 10 L/minute by nonrebreather face mask. 7. Notify physician or nurse-midwife. 8. Consider internal monitoring for a more accurate fetal and uterine assessment. 9. Assist with birth (cesarean or vaginal assisted) if the pattern cannot be corrected.
nursing interventions for variable decels
The usual priority is as follows: 1. Change maternal position (side to side, knee-chest). 2. Discontinue oxytocin if infusing. 3. Administer oxygen at 8 to 10 L/minute by nonrebreather face mask. 4. Notify physician or nurse-midwife. 5. Assist with vaginal or speculum examination to assess for cord prolapse. 6. Assist with amnioinfusion if ordered. 7. Assist with birth (vaginal assisted or cesarean) if the pattern cannot be corrected.
causes of variable decels
Umbilical cord compression caused by the following: • Maternal position with cord between fetus and maternal pelvis • Cord around fetal neck, arm, leg, or other body part • Short cord • Knot in cord • Prolapsed cord
when is a tocotransducer NOT effective?
Unable detect if obese Not able detect if preterm pregnancy • Fundus might be below level of umbilicus • Use palpation as well to assess frequency and validate monitor tracing
vibroacoustic stimulation
Using artificial larynx or fetal stimulation device on maternal abdomen over the fetal head for 1-5 seconds Desired result: acceleration in FHR of at least 15 bpm for at least 15 seconds • Acceleration indicates absence of metabolic academia • If do NOT respond with acceleration - compromise is NOT necessarily indicated • Further evaluation required Performed at times when FHR at baseline • NOT if decelerations or bradycardia present
fetal scalp stimulation
Using digital pressure during vaginal exam Desired result: acceleration in FHR of at least 15 bpm for at least 15 seconds • Acceleration indicates absence of metabolic academia • If do NOT respond with acceleration - compromise is NOT necessarily indicated • Further evaluation required Performed at times when FHR at baseline • NOT if decelerations or bradycardia present
strength
Uterine contractions generally range from peaking at 40-70 mm Hg in first stage of labor to more than 80 mm Hg in second stage. Contractions palpated as "mild" will likely peak at less than 50 mm Hg if measured internally, whereas contractions palpated as "moderate" or greater will likely peak at 50 mm Hg or greater if measured internally.
clinical significance of variable decels
Variable decelerations occur in approximately 50% of all labors and usually are transient and correctable
variable decelerations
Visually abrupt (onset to nadir less than 30 seconds) decrease in FHR below baseline • Decrease at least 15 bpm or more below baseline • Lasts at least 15 seconds • Returns to baseline in less than 2 minutes from time of onset • Occur any time during UC phase Caused by compression of umbilical cord
prolonged deceleration
Visually apparent decrease (gradual or abrupt) in HFR of at least 15 bpm below baseline • Last longer than 2 minutes • Less than 10 minutes • If more than 10 minutes → change in baseline Caused when mechanisms for late/variable decels last for extended period (more than 2 minutes)
early decelerations
Visually apparent gradual (onset to lowest point MORE than 30 seconds) decrease in and return to baseline FHR associated with UCs Onset, nadir (lowest point), and recovery correspond with beginning, peak and end of contraction • Mirror image of contraction
late decelerations
Visually apparent gradual decrease in and return to baseline FHR associated with UCs • Begins AFTER contraction started • Nadir of deceleration occurs AFTER peak of contraction • Usually does not return to baseline until after contraction over Attributed to uteroplacental insufficiency
what are the four categories of variability?
absent - undetectable minimal: < 5 bpm moderate: 6-25 bpm marked: amplitude > 25 bpm
what is the expected result of fetal scalp stimulation?
acceleration in FHR of at least 15 bpm for at least 15 seconds
what is the expected result of vibroacoustic stimulation?
acceleration in FHR of at least 15 bpm for at least 15 seconds
what is a "mild" strength contraction measured at?
below 50 mmHg
what happens if an acceleration lasts 10 minutes?
change in baseline
nurses who are caring for women during childbirth are legally responsible for what?
correctly interpreting FHR patterns, initiating appropriate nursing interventions based on those patterns, and documenting the outcomes of those interventions. Perinatal nurses are responsible for the timely notification of the physician or nurse-midwife in the event of abnormal FHR patterns. They also are responsible for initiating the institutional chain of command should differences in opinion arise among health care providers concerning the interpretation of the FHR pattern and the intervention required.
nursing interventions for bradycardia
depend on cause
when is tocolytic therapy used?
excessive spontaneous UCs or after decision for cesarean
ultrasound transducer
external route High-frequency sound waves reflect mechanical action of the fetal heart. Noninvasive. Does not require rupture of membranes or cervical dilation. Used during both the antepartum and intrapartum periods.
tocotransducer
external route Monitors frequency and duration of contractions by means of a pressure-sensing device applied to the maternal abdomen. Used during both the antepartum and intrapartum periods.
acid base of umbilical arteries indicate what?
fetal condition
how are non spontaneous accelerations caused?
fetal scalp stimulation vibroacoustic stimulation
what kind of decent is a early decel?
gradual more than 30 seconds
causes of decreased O2 supply to fetus through Reduction of the oxygen content in the maternal blood
hemorrhage severe anemia
what benefits does tocolytic therapy have?
increase of blood flow through placenta by inhibiting UCs
spiral electrode
internal route Converts the fetal ECG as obtained from the presenting part to the FHR via a cardiotachometer. Can be used only when membranes are ruptured and the cervix is sufficiently dilated during the intrapartum period. Electrode penetrates the fetal presenting part by 1.5 mm and must be attached securely to ensure a good signal.
IUPC = intrauterine pressure conductor
introduced in uterine cavity → UA o Compressed during contraction → frequency, duration, intensity and uterine resting tone Montevideo units (MVUs): • Calculated by subtracting the baseline uterine pressure from the peak contraction pressure for each contraction that occurs in a 10 minute window • Adding together the pressures generated by each contraction that occurs during that period of time • Spontaneous labor usually beings when MVUs are between 80 and 120 • UA during normal labor rarely exceeds 250 MVUs
occasional variable decels
little significance
what is the max amount of fluid during amnioinfusion?
no more than 1000 mL Record amount of fluid return - prevent overdistention of uterus • Volume returned same as volume infused
interventions for early decel
none
nursing interventions for accelerations
none
what terms are used to describe FHR tracing?
normal and abnormal clinically: reassuring vs nonreassuring
what should you do if you see a prolonged decel?
notify PCP or nurse midwife immediately
advantages of intermittent auscultation
o Easy to use, inexpensive, less invasive than EFM o More comfortable o Freedom of movement - ambulation and use of baths/showers easier o Transvaginal fetal Doppler probe available - closer proximity to uterus = easier to auscultate in obese or early gestation
evaluation of EFM equipment
o Ensure monitor recording FHR and UA accurately o Tracing interpretable
bradycardia - causes
o Fetal cardiac problem - structural defects involving pacemakers o Condition of system or fetal HF o Viral infections (cytomegalovirus) o Maternal hypoglycemia o Maternal hypothermia
intermittent auscultation disadvantages
o Intermittent → significant events may occur when not auscultating o Does not provide permanent documented visual record of FHR - cannot be used to assess visual patterns of FHR variability of periodic changes o Requires one to one nurse-to-client staffing ratio
tachycardia - results from
o Maternal/fetal infection o Prolonged rupture of membranes with amnionitis o Maternal hyperthyroidism o Fetal anemia o Response to meds: atropine, hydroxyzine, Terbutaline, illicit drugs (cocaine, meth)
sinusoidal pattern
o Regular smooth, undulating wavelike pattern o Not included in definition of FHR variability o Uncommon pattern → severe fetal anemia Associated with • Chorioamnionitis • Fetal sepsis • Administration of narcotics
doppler US and US stethoscope (IA)
o Transmit high frequency sound waves, reflecting movement of fetal heart, convert into electronic signal that can be counted o Fetoscope applied to listener's forehead = bond conduction amplifies FHR sounds
what is tested for acid base balance in the umbilical cord?
pH pCO2 pO2 base deficit or base excess
approximate cord blood values - artery
pH 7.2-7.3 pCO2: 45-55 pO2: 15-25 base deficit: <12
approximate cord blood values - vein
pH 7.3-7.4 pCO2: 35-45 pO2: 25-35 base deficit: <12
what is the pH of acidemia
pH < 7.20
mixed acidosis
pH < 7.20 pCO2: elevated base deficit: > 12 mmol/L
metabolic acidosis
pH < 7.20 pCO2 normal base deficit > 12 mmol/L
respiratory acidosis
pH < 7.20 pCO2: elevated base deficit: < 12 mmol/L
what are the credentials for an acceleration of a baby 32 weeks?
peak of 10 bpm or more above baseline duration of at least 10 seconds
what are the criteria for an acceleration?
peak of 15 bpm above baseline lasts 15 second or more return to baseline less than 2 minutes from beginning
acid base of umbilical veins indicate what?
placental function
where is the spiral electrode attached to on the fetus?
presenting part
how can fetal oxygen supply decrease
reduction of BF through maternal vessels reduction of O2 content in maternal blood alterations in fetal circulation reduction in BF to intervillous space in the placenta
tocolysis
relaxation of uterus
recurrent variable decels
repetitive disruption in fetus's oxygen supply • Hypoxemia results → metabolic acidosis • Most common in transition phase or second stage = umbilical cord compression and stretching during fetal descent
how do you round to determine baseline FHR?
round to closest 5 bpm
what devices are used for internal FHR monitoring?
spiral electrode - fetal ECG intrauterine pressure catheter - contractions
what drug is used for tocolytic therapy? how is it administered?
sub-q terbutaline: Brethine
terbutaline: Brethine
sub-q tocolytic therapy - relax uterus, prevent UCs Quick onset Improve Apgar scores and cord pH values No complications • If no improvement - immediate cesarean
which external monitor is placed ABOVE the mother's umbilicus?
tocotransducer (contractions)
what devices are used for external FHR monitoring?
ultrasound transducer - fetal heart tocotransducer - contractions
where is the PMI located on the fetus?
usually over fetal back clearest and loudest sound
what's the most common cause of late decels?
uterine tachysystole (more than 5 contractions in 10 minutes averaged over 30 minutes) caused by oxytocin (Pitocin) admin
when should fetal scalp stimulation be performed?
when FHR at baselines NOT decelerations or bradycardia present
asphyxia
when fetal hypoxia results in metabolic acidosis
when is fetal tachycardia considered abnormal?
with late decels severe variable decels absent variability
tocolytic therapy
• Administer drugs that inhibit UCs • When fetus abnormal patterns associated with increased UA • Improves blood flow through placenta by inhibiting UCs • When other methods not successful • Maternal position change • Discontinue oxytocin Excessive spontaneous UCs or after decision for cesarean
basic interventions for abnormal FHR patterns
• Administer oxygen by nonrebreather face mask at a rate of 10 L/minute for approximately 15 to 30 minutes. • Assist the woman to a side-lying (lateral) position. • Increase maternal blood volume by increasing the rate of the primary IV infusion.
moderate variability
• Amplitude range 6-25 bpm • Considered normal • Predictive of normal fetal acid base balance • FHR regulation is not significantly affected by fetal sleep cycles, tachycardia, prematurity, congenital anomalies, preexisting neuro injury, or CNS depressant meds
marked variability
• Amplitude range > 25 bpm • Significance unknown
minimal variability
• Amplitude range detectable < 5bpm • Abnormal or indeterminate • Result from: • Fetal hypoxemia • Metabolic academia • Congenital anomalies • Preexisting neuro injury • CNS depressant meds: analgesics, narcotics (meperidine (Demerol), barbiturates, tranquilizers (diazepam = Valium, phenothiazines), general anesthesia • Tachycardia • Prematurity • Fetus temporarily in sleep state - usually no longer than 30 minutes
absent variability
• Amplitude range undetectable • Abnormal or indeterminate Result from: • Fetal hypoxemia • Metabolic academia • Congenital anomalies • Preexisting neuro injury • CNS depressant meds: analgesics, narcotics (meperidine (Demerol), barbiturates, tranquilizers (diazepam = Valium, phenothiazines), general anesthesia • Tachycardia • Prematurity • Fetus temporarily in sleep state - usually no longer than 30 minutes
what can interact with sound in an US transducer?
• Artifact by fetal movement • Maternal obesity • Occiput posterior position of fetus • Anterior attachment of placenta
what are the five essential components of FHR tracing?
• Baseline rate • Baseline variability • Accelerations • Decelerations • Changes or trends overtime
how do you document with IA?
• Because they are VISUAL descriptions of patterns - moderate variability, variable deceleration • Terms that are numerically defined: • Bradycardia vs. tachycardia • Described as baseline number or range - regular or irregular rhythm • Presence of absence of accelerations or decelerations during/after contractions should be noted
which meds can cause absent or minimal variability?
• CNS depressant meds: analgesics, narcotics (meperidine (Demerol), barbiturates, tranquilizers (diazepam = Valium, phenothiazines), general anesthesia
how do you calculate Montevideo units? (MVUs)
• Calculated by subtracting the baseline uterine pressure from the peak contraction pressure for each contraction that occurs in a 10 minute window • Adding together the pressures generated by each contraction that occurs during that period of time • Spontaneous labor usually beings when MVUs are between 80 and 120 • UA during normal labor rarely exceeds 250 MVUs
when do you test umbilical cord acid base balance?
• Cesarean birth for fetal compromise • Low 5 minute Apgar score • Severe intrauterine growth restriction • Abnormal FHR tracing • Maternal thyroid disease • Intrapartum fever • Multifetal gestation
causes of decreased O2 supply to fetus through alterations in fetal circulation
• Compression of the umbilical cord (transient, during uterine contractions [UCs], or prolonged, resulting from cord prolapse) • Placental separation or complete abruption • Head compression (head compression causes increased intracranial pressure and vagal nerve stimulation with an accompanying decrease in the FHR)
the presence/degree of fetal hypoxia is correlated with what?
• Depth and duration of decel • How abruptly returns to baseline • Hoe much variability is lost during decel • Whether rebound tachy and loss of variability occur after decel
how is the appearance of variable decels different than early/late?
• Early/late: follow shape of corresponding UC • Variable: have U, V, or W shape - rapid descent and ascent to and from nadir of decel Shoulders: • Variable decels preceded and followed by brief acceleration of FHR • Compensatory response to compression of umbilical vein
advantages of Monica AN24
• Eliminates issues with signal loss form maternal or fetal movement, maternal obesity • More accurately measures frequency, peak, duration of UCs - does NOT measure intensity in mmHg • Eliminate need for belts and frequent readjustment • Provides mobility - 50 feet without signal loss • Approved for 36+ week pregnancies
how often should you auscultate (IA) in low risk women?
• Every 15 minutes in active phase of first stage (every 30 minutes) • Every 5 minutes in second stage (every 15 minutes)
family teaching when electronic fetal monitor used
• Explain the purpose of monitoring. • Explain each procedure. • Provide rationale for maternal position other than supine. • Explain that fetal status can be continuously assessed by electronic fetal monitoring (EFM), even during contractions. • Explain that the lower tracing on the monitor strip paper shows uterine activity (UA); the upper tracing shows the fetal heart rate (FHR). • Reassure woman and partner that prepared childbirth techniques can be implemented without difficulty. • Explain that during external monitoring effleurage can be performed on sides of abdomen or upper portion of thighs. • Explain that breathing patterns based on the time and intensity of contractions can be enhanced by the observation of uterine activity on the monitor strip, which shows the onset of contractions. • Note peak of contraction; knowing that the contraction will not get stronger and is halfway over is usually helpful. • Note diminishing intensity. • Coordinate with appropriate breathing and relaxation techniques. • Reassure woman and partner that the use of internal monitoring does not restrict movement, although she is confined to bed.∗ • Explain that use of external monitoring usually requires the woman's cooperation during positioning and movement. • Reassure woman and partner that use of monitoring does not imply fetal jeopardy.
interventions for abnormal FHR related to maternal hypotension
• Increase the rate of the primary IV infusion. • Change to lateral or Trendelenburg positioning. • Administer ephedrine or phenylephrine per unit protocol or standing order if other measures are unsuccessful in increasing blood pressure.
how do you assess uterine activity by palpation?
• Keep fingertips placed over fundus before, during and after contractions • Intensity: mild, moderate or strong • Duration: seconds from beginning to end • Frequency: in minutes - beginning of one contraction to beginning of next • Evaluate resting tone or relaxation between contractions • Soft or hard
causes of decreased O2 supply to fetus through Reduction of blood flow through the maternal vessels
• Maternal hypertension (chronic hypertension, preeclampsia, or gestational hypertension) • Hypotension (caused by supine maternal position, hemorrhage, or epidural analgesia or anesthesia) • Hypovolemia (caused by hemorrhage)
what are some factors that decrease oxygen transfer to the fetus - with mild UCs and functioning placenta - causing late decels?
• Maternal hypotension • Uterine tachysystole • More than 5 contractions in 10 minutes averaged over 30 minute window • Preeclampsia • Late term/postterm pregnancy • Amnionitis • Small for gestational age fetus • Maternal DM • Placenta previa • Placental abruption • Conduction anesthetics • Maternal cardiac disease • Maternal anemia • Metabolic academia
what are the risks of amnioinfusion?
• Overdistnsion of uterine cavity • Increased uterine tone No more than 1000 mL administered • Fluid can be warmed Record amount of fluid return - prevent overdistention of uterus • Volume returned same as volume infused
what is excluded from the strip during determination of FHR?
• Periodic or episodic changes • Periods of marked variability • Segments of the baseline that differ by more than 25 beats/minute
interventions for abnormal FHR related to uterine tachysystole
• Reduce or discontinue the dose of any uterine stimulants in use (e.g., oxytocin [Pitocin]). • Administer a uterine relaxant (tocolytic) (e.g., terbutaline [Brethine]).
what is fetal scalp blood sampling limited by?
• Requirement for cervical dilation • Membrane rupture • Technical difficulty of procedure • Need for repetitive pH determinations • Uncertainty regarding interpretation and application of results
causes of accelerations
• Spontaneous fetal movement • Vaginal examination • Electrode application • Fetal scalp stimulation • Fetal reaction to external sounds • Breech presentation • Occiput posterior position • Uterine contractions • Fundal pressure • Abdominal palpation
interventions for abnormal FHR related to abnormal FHR pattern during second stage of labor
• Use fewer pushing efforts during each contraction. • Make individual pushing efforts shorter. • Push only with every other or every third contraction. • Push only with a perceived urge to push (in women with regional anesthesia).
causes of decreased O2 supply to fetus through reduction in blood flow to the intervillous space in the placenta
• Uterine hypertonus (generally caused by excessive exogenous oxytocin) • Deterioration of the placental vasculature • Post-term gestation • Maternal disorders such as hypertension or diabetes mellitus
what causes oligohydramnios or anhydramnios?
• Uteroplacental insufficiency • Premature rupture of membranes • Anomalies that prevent or reduce fetal urine production
shoulders (variable decels)
• Variable decels preceded and followed by brief acceleration of FHR • Compensatory response to compression of umbilical vein
what are the three major interventions during intrauterine resuscitation?
• When abnormal FHR pattern noted • Supplement oxygen • Maternal position changes • Increase IV fluids
what happens when amniotic fluid is low?
• Without amniotic fluid - cord easily compressed during contraction or fetal movement = decrease oxygen and blood flow • Relieve intermittent umbilical cord compression → variable decels and transient fetal hypoxemia
