Fetal Heart rate assessment ch9 Flashcards
(36 cards)
Electronic fetal monitoring
The goal of fetal monitoring is to interpret and continually assess fetal oxygenation (Lyndon & Ali, 2015) and prevent significant fetal acidemia while minimizing unnecessary intervention and promoting a satisfying family-centered birth experience.
While it is essential in the assessment of maternal and fetal well-being in antepartal and intrapartal settings, keep in mind that other evidence-based options such as intermittent auscultation are appropriate for laboring women
Principles of Fetal Monitoring
Overall Goals
● Support maternal coping and labor progress
● Maximize uterine blood flow
● Maximize umbilical blood flow
● Maximize oxygenation
● Maintain appropriate uterine activity
Nursing Actions
● Review plans/expectations with woman and her family
● Maintain calm environment
● Stay at the bedside as much as possible
● Monitor only at the level needed for this patient
● Frequent position changes; upright positioning
● Judicious use of technology
● Avoid:
● Unnecessary interventions
● Tachysystole
● Supine position
● Coached pushing
● Valsalva pushing
Nurses are expected to independently assess, interpret, and intervene based on interpretations of EFM patterns. Assessments and interactions with monitored women and their families are individualized to provide information and explanation and reduce anxiety (Box 9-2). Clear and accurate communication with care providers and the perinatal team is essential for optimizing perinatal outcomes.
AWHONN Fetal Heart Monitoring Clinical Position Statement
The Association of Women’s Health, Obstetric and Neonatal Nurses (AWHONN) asserts that care by registered nurses (RNs) skilled in fetal heart monitoring (FHM) techniques, including auscultation and electronic fetal monitoring (EFM), is essential to maternal and fetal well-being during antepartum care, labor, and birth. EFM requires advanced assessment and clinical judgment. It is within the nurse’s scope of practice to implement customary interventions in response to FHM data and clinical assessment. Interprofessional policies should support the RN in making decisions regarding fetal monitoring practice, intervening independently when appropriate to maternal and/or fetal condition.
Teamwork and Collaboration
- Following communication practices that minimize risks associated with EFM communication among providers.
- Appreciating the importance of intra- and interprofessional collaboration to improve patient outcomes.
- Integrating the contributions of others who play a role in helping patient and her family achieve a healthy birth.
- Respecting the centrality of the patient/family as core members of any health care team.
- Acknowledging your own potential to contribute to effective team functioning in this critical setting.
MODES OR TYPES OF FETAL AND UTERINE MONITORING
Types of fetal and uterine monitoring include the following.
Auscultation
Auscultation refers to the use of the fetoscope or Doppler to listen to the FHR without the use of a paper recorder (Feinstein, Sprague, & Trepanier, 2008) (Fig. 9–1A&B). Auscultation with a fetoscope allows the practitioner to hear the sounds associated with the opening and closing of ventricular valves via bone conduction. A Doppler, by contrast, uses sound waves that are deflected from fetal heart movements similar to that used on an EFM external ultrasound transducer. This ultrasound device then converts information into a sound that represents cardiac events.
Baseline FHR
FHR rounded to increments of 5 bpm during a 10-minute window. There must be at least 2 minutes of identifiable baseline segments (not necessarily contiguous). Does not include accelerations or decelerations or periods of marked variability (amplitude >25 bpm).
- Periodic: changes in baseline of FHR occur in relation to UCs.
- Episodic: changes in baseline of FHR occur independent of UCs.
- Recurrent: changes in baseline of FHR occur in greater or equal to 50% of the contractions in a 20-minute period.
- Intermittent: changes in baseline of FHR in less than 50% of the contractions in a 20-minute period.
Baseline variability
Fluctuations in the baseline FHR that are irregular in amplitude and frequency. The fluctuations are visually quantified as the amplitude of the peak to trough in bpm. It is determined in a 10-minute window, excluding accelerations and decelerations. It reflects the interaction between the fetal sympathetic and parasympathetic nervous system.
- Absent: Amplitude range is undetectable.
- Minimal: Amplitude range is visually detectable ≤5 bpm.
- Moderate: Amplitude from peak to trough is 6 bpm to 25 bpm.
- Marked: Amplitude range >25 bpm.
Indeterminant FHR
FHR that does not meet the criteria of baseline FHR
Accelerations
Visually apparent, abrupt increase in FHR above the baseline. The peak of the acceleration is ≥15 bpm over the baseline FHR for ≥15 seconds and <2 minutes.
• Before 32 weeks’ gestation, acceleration is ≥10 beats over the baseline FHR for ≥10 seconds.
Prolonged accelerations are ≥2 minutes but ≤10 minutes.
Deceleration
Transitory decrease in the FHR from the baseline.
- Early deceleration is a visually apparent gradual decrease in FHR from baseline to nadir (lowest point of the deceleration) taking more than 30 seconds. The nadir occurs at the same time as the peak of the UC. Onset, nadir, and recovery match the onset, peak, and end of the UC. It’s always periodic.
- Variable deceleration is a visually apparent abrupt decrease in the FHR from baseline to nadir taking less than 30 seconds. The decrease in FHR is greater or equal to 15 bpm and less than 2 minutes in duration. It can be periodic or intermittent.
- Late deceleration is a visually apparent gradual decrease of FHR from baseline to nadir taking more than 30 seconds. Nadir occurs at the peak of the UC. Onset, nadir, and recovery after the respective onset, peak, and end of the UC. Always periodic.
- Prolonged deceleration is a visually apparent abrupt or gradual decrease in FHR below baseline that is ≥15 bpm lasting ≥2 minutes but ≤10 minutes. It can be periodic or intermittent.
Variation in baseline
Sinusoidal pattern: visually apparent smooth sine wave like undulating pattern in FHR baseline with a cycle frequency of 3-5/minutes that persists for ≥20 minutes. Benign sinusoidal patterns contain accelerations that last less than 20 minutes. A sinusoidal appearing FHR pattern can occur following maternal administration of some opioids (butorphanol and fentanyl). This undulating FHR pattern is of short duration and is also referred to as pseudosinusoidal or medication-induced sinusoidal
Tachycardia
• Baseline FHR of > 160 bpm lasting 10 minutes or longer.
Bradycardia
Baseline FHR of < 110 bpm lasting for 10 minutes or longer.
Normal FHR
Category I (see Critical Component: Three-Tier FHR Interpretation System) reflects absence of metabolic acidemia at the time the EFM pattern is observed (AWHONN, 2015), and reflects favorable physiological response to maternal-fetal environment.
Abnormal FHR
Category II and III (see Critical Component: Three-Tier FHR Interpretation System) reflects unfavorable physiological response to maternal fetal environment.
Common Abbreviations for Electronic Fetal Monitoring
ED Early deceleration EFM Electronic fetal monitoring FHR Fetal heart rate FSE Fetal scalp electrode IA Intermittent auscultation IUPC Intrauterine pressure catheter LD Late deceleration MVU Montevideo units PD Prolonged deceleration TOCO Tocodynamometer VAS Vibroacoustic stimulation UC Uterine contractions US Ultrasound VD Variable deceleration VE Vaginal examination
Paper recorder
A paper recorder provides additional information on a tracing for clinician assessment, such as determining the difference between the categories in the three-tiered FHR interpretation system. This is because auscultation limits assessment data to FHR baseline, rhythm, and changes from baseline. Auscultation cannot detect certain types of decelerations and variability that can be detected by a combination of a paper recorder and ultrasound technology (part of electric monitoring).
Recent research
Research evidence supports the use of structured intermittent auscultation (SIA) as a method of fetal surveillance during labor for low-risk pregnancies (Feinstein et al., 2008; Lyndon & Ali, 2015; True & Bailey, 2016). An updated position statement from ACOG supports intermittent auscultation in low risk pregnancy in labor (ACOG, 2017
Guidelines and Procedure for Auscultation
- Explain the procedure to the woman and her family.
- Palpate the maternal abdomen to determine fetal position (Leopold’s maneuvers).
- Place the Doppler over the area of maximum intensity of fetal heart tones, generally over the fetal back.
- Palpate maternal radial artery to differentiate maternal heart rate from FHR.
- Determine relationship between uterine contractions (UCs) and FHR by palpating for UCs during period of FHR auscultation.
- Count FHR between contractions for at least 30 to 60 seconds to determine the baseline rate.
- Determine differences between baseline FHR and fetal response to contractions by counting FHR after a UC using multiple consecutive 6- to 10-second intervals for 30 to 60 seconds (protocols may differ based on location).
Fetoscope /doppler
Normal findings of SIA include normal baseline between 110 and 160 beats per minute (bpm) and regular rhythm; presence of FHR increases from baseline, and the absence of FHR decreases from baseline. To identify the baseline rate, the FHR should be auscultated and counted between contractions when the fetus is not moving for at least 30 to 60 seconds. Once the baseline is established, the FHR is then auscultated and counted while palpating maternal pulse for 15 to 60 seconds between contractions (Killion, 2015) (see Box 9–4). Successful implementation of SIA can be achieved by considering the following guidelines:
● Presence of nurses and providers experienced in auscultation and recognition of auditory changes in FHR
● Institutional policy developed to address the technique and frequency of assessment
● Clinical interventions (e.g., change to EFM) when concerning findings are present
● Nurse to laboring women ratio of 1:1
● User-friendly documentation tools for recording SIA findings
● Ready availability of auscultation devices
● Culture embracing the normalcy of childbirth and minimization of unnecessary interventions (True & Bailey, 2016)
In summary, fetoscope and Doppler obtain information differently but are both appropriate in certain auscultation clinical situations.
Palpation of Contractions
● Palpation of uterine contractions is done by the nurse placing her fingertips on the fundus of the uterus and assessing the degree of tension as the contractions occur.
● The intensity of contractions is measured at the peak of the contraction and is rated as:
● Mild or 1+ feels like the tip of the nose (easily indented)
● Moderate or 2+ feels like the chin (can slightly indent)
● Strong or 3+ feels like the forehead (cannot indent uterus)
● The resting tone is measured between contractions and listed as either soft or firm uterine tone.
● Palpation is a subjective assessment and can be biased by the fat distribution on the pregnant woman’s abdomen.
External Electronic Fetal and Uterine Monitoring
External electronic fetal and uterine monitoring uses an ultrasound device to detect FHR and a pressure device to assess uterine activity, which is attached to a paper recorder
● The FHR is measured via an ultrasound transducer, an external monitor.
● External EFM detects FHR baseline, variability, accelerations, and decelerations.
● External heart rate monitors receive waveforms from the fetal heart interpreted by the computer in the fetal monitor to produce audible sound and visual tracing to reflect the FHR.
● Fetal monitors average three consecutive beat-to-beat intervals and then assign the FHR
providers are instructed to take precautions against misinterpretations by verification of FHR via monitoring of maternal heart rate via palpating the maternal radial pulse and maternal pulse oximetry
Monitoring of both fetal and maternal heart rate
● Today, many EFMs allow the monitoring of both the FHR and the maternal heart rate (MHR) via sensors within the tocodynamometer (TOCO), both appearing on the printout paper. MHR usually is significantly lower than the FHR and tends to increase as labor progresses and during contractions and pushing efforts.
● Location of the FHR via EFM changes in maternal position and as the fetus descends during labor, especially in the second stage (AWHONN, 2015; Lyndon et al., 2015).
● Erratic FHR recordings or gaps on a paper recorder may be caused by inadequate conduction of ultrasound signal, displacement of the transducer (may be picking up maternal heart rate), fetal or maternal movement, inadequate ultrasound gel, or fetal arrhythmia (may need to auscultate to verify).
Measuring contractions
● Contractions are measured via TOCO, also an external uterine monitor.
● The relative frequency and duration of uterine contractions (UCs) and relative resting tone, which is the tone of the uterus between contractions, can be measured by this method.
● External contraction monitor, TOCO, is a strain gauge that detects skin tightness or contour changes resulting from UCs. It should be placed via palpation at the uterine fundus, during maximum uterine contraction intensity, ideally at a smooth part of the uterus where no fetal small parts are felt. Appropriate placement of the TOCO may change during labor. Also, it may be more difficult to monitor tightening of the skin with increased fat distribution around the maternal abdomen.
● External uterine monitors cannot measure pressure/intensity of contractions.
● Pressure/intensity of the contraction must be estimated by palpation of contractions.
● Contractions not recording on a paper recorder may occur when the transducer is placed away from strongest area of contraction or when resting tone is not dialed to 10 to 20 mm Hg when the uterus is relaxed.
