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Fetal Heart monitoring AWHONN basics
Mother's inhalation to lungs to mat. circulatory system to hemoglobin in RBC's to bloodstream in uterus. Uterus to spiral arteries to placenta to intervillous space to travel via simple diffusion into the villi. The capillaries to the umb. vein to the fetus. The umb. artery sends waste (CO2) to the intervillous space to the mothers venous system. - ✔✔Trace the flow of oxygen from mother to fetus and back.
- Mother (blood plasma, cardiac output, hemoglobin concentration & O2 saturation)
- Placenta/intervillous space (uterine contractions & calcification's)
- Fetus (vagal response aka decel or cord compression) - ✔✔What factors impact maternal oxygen delivery? 30 - 50% lateral recumbent or semi-Fowler's - ✔✔By what % does maternal cardiac output increase above the non- pregnant state and what position helps this uteroplacental blood flow?
5 contractions in 10 min (more frequently than Q 2 min) averaged over 30 min window. Caused by oxytocin, aminoinfusion or in rare cases spontaneously. - ✔✔Define tachysystole contractions and the cause of. Maintaining mat. volume, mat. positioning, intravenous hydration. Decreasing mat. pain/anxiety.
- Reposition pt to side.
- Admin IV fluid bolus.
- Admin 0.25mg terbutaline SQ.
- Admin O2 10L via non rebreather face mask. - ✔✔List interventions for tachysystole contractions. higher conc. to lower concentration.
1.Oxygen from maternal (higher) to fetal compartment (lower) to fetal hgb then transported to fetal tissue.
- CO2 returns to intervillous space by passive diffusion and is removed by the mat. venous system. - ✔✔Describe passive diffusion as related to the maternal placental fetal system. Place her in lateral position, & increase IV fluids. If no improvement may need to give epi to increase vascular tone. - ✔✔Maternal hypotension is a potential side effect of regional anesthesia and analgesia. What nursing interventions could you use to raise the client's blood pressure? Choose all that apply. A) Place the woman in a supine position. B) Place the woman in a lateral position. C) Increase intravenous (IV) fluids. D) Continuous Fetal Monitor E) Administer ephedrine per MD order systolic BP >= 140mm hg, a diastolic BP>= 90 mm hg or MAP of >=105 - ✔✔Define maternal hypertension (gestational). 17g/dl, fetal hgb has a higher oxygen affinity than an adult to develop in an oxygen poor environment. The fetal circulatory pattern ensures blood with higher O2 and nutrition content is delivered to the vital organs (brain and heart) to tolerate the stress of labor. - ✔✔What is the normal expected value for a term fetal HGB? 1 vein, 2 arteries encased in wharton's jelly. O2 (high content) travels via the vein CO2 travels via 2 arteries back to placenta - ✔✔detail the umbilical cord b) Duration - ✔✔Which contraction characteristics can be assessed with a tocodynamometer? a) Frequency b) Duration c) Intensity
Chronic deficiency of placenta function, usually from an interruption of oxygenation pathway due to abruption, mat. hypo or hypertension or other issues. Infant is not tolerant of contractions. Can result in fetal grow restrictions (FGR) - ✔✔Define Uteroplacental insufficiency (UPI) Assess baseline FHR Determine rhythms (regular vs irregular) ID accelerations and deceleration's but not the type of deceleration (early/late/variable) The fetal heartbeat is best heard over the fetal back. - ✔✔Auscultation of Fetal Heart Sounds tell you what information? Where is the best place to listen? Palpation to determine presentation and position of the fetus and aid in location of fetal heart sounds. Head=hard, round, movable object Buttocks=soft and irregular shape Back=smooth, hard surface felt on one side of the abdomen Irregular knobs and lumps on opposite side of abdomen may be hands, feet, elbows, and knees - ✔✔Leopold's Maneuvers Uses sonar to track the fetal myocardium & converts movement into sound. If placed incorrectly may pick up maternal heart. Perform Leopold's maneuvers to find fetal back, locate heartbeat, count FHR, check mothers pulse and compare. - ✔✔Handheld Fetal Doppler ID risk factors such as HTN (=vasoconstriction), Maternal smoking, abruption, post-term pregnancy, maternal diabetes and consider FHR characteristics - ✔✔How can you determine if the placenta is functioning optimally? 500 - 700ml to the uterus per minute, 80% is directed to the placenta - ✔✔How much blood normally flows to the placenta?
This depends on oxygenation which is reflected in FHR variability and accelerations on the fetal monitor tracings. - ✔✔How many uterine contractions can be tolerated? Umb. cord - Proplapse Mat. inhalation - Asthma Placenta - Calcification Uterus - Tachysystole Fetus - Rh isoimmunization (fetal anemia) Mat. circulation - Hypertension - ✔✔What conditions impact the following pathways: Umbilical cord Maternal inhalation Placenta Uterus Fetus Maternal circulation Helps Assess Fetal Well-Being Can Use external Doppler US Device or Internal Fetal Scalp Electrode Should Be Monitored Every 30 Minutes in Stage I, Every 15 Minutes in Stage 2 - ✔✔Fetal Heart Rate Monitoring (two methods) 10 - 20 mm Hg (this is an arbitrary #) Toco detects increases and decreases but can not quantify pressure. - ✔✔When using toco what do you set the uterine resting tone or baseline to? What is toco measuring?
At least 200 MVU's results in progressive cervical change. - ✔✔What is a Montevideo unit (MVU)? How do you calculate MVU's? Using your fingertips at the fundus you can assess duration and frequency. Intensity: nose= mild chin=moderate forehead=strong - ✔✔How do you palpate a contraction? Describe the intensities. Monitors changes in the contour of the maternal abdomen caused by uterine contractions, is placed over the fundus. Can measure relative changes in pressure, duration and frequency of contractions. Can NOT measure intensity. Women with large amounts of abdominal adipose tissue can be difficult to monitor. - ✔✔Explain what a Tocodynamometer is, what it measures and its limitations. Most accurate method of assessing uterine contractions. Inserted through dilated cervix, its sensor tip monitors changes in pressure of the amniotic fluid. Measures resting tone, duration, frequency and intensity of contractions. Can NOT be used unless membranes are ruptured. - ✔✔Explain what an intrauterine pressure catheter is, what it measures and its limitations. Fetal heart rate patterns 5 characteristics 1 Baseline heart rate 2 Rhythm 3 FHR variability 4 Presence of accelerations 5 Periodic or episodic deceleration's - ✔✔How do you determine fetal oxygenation? Name the 5 characteristics Must be 2 min of segments.
Range 110-160 BPM (represented in a multiple of 5) <32 weeks is usually high normal
32 weeks gradual decrease due to increased vagal tone. Change in baseline is >10min. - ✔✔What are fetal baseline guidelines? Range? <32 weeks gest 32 weeks gest change in baseline It is the heart's internal pacemaker. It is specialized clump of cells at the top of the right atrium that gives electrical impulses to cause the heart to beat. The intrinsic rate is 110-160 in term fetus. Early in gestation (15-20 wks) can be much higher. In 26-28 weeks may be in the upper range of normal. - ✔✔What is the SA Node? Generated in the fetal brainstem carried via sympathetic fibers to the heart. Increases FHR, strength of myocardial contraction of the heart and fetal cardiac output. Sympathetic stimulation influences FHR variability. The sympathetic branch of the autonomic nervous system is present very early in fetal development. - ✔✔Explain the sympathetic impulses of the fetal central nervous system. Generated in the fetal brainstem carried via the vagus nerve to the fetal heart. Stimulates vagus nerve which increases fetal blood pressure, decreases firing rate at SA node and decreases FHR. Also influences the presence of fetal heart variability. The parasympathetic nervous system matures later in pregnancy. This balances out the sympathetic branch, the baseline heart rate gradually decreases toward the middle of the normal range. - ✔✔Explain the parasympathetic impulses of the fetal central nervous system. Baseline FHR is 130 BPM which falls within the range of normal baselines 110-160 BPM - ✔✔Is the baseline in this fetal tracing of a fetus at 40 weeks gestation normal or abnormal? Baseline FHR is 135 BPM which falls within the range of normal baselines 110-160 BPM - ✔✔Is this baseline in this fetal tracing of a fetus at 26 weeks gestation normal or abnormal?
amplitude range 6-25 BPM - ✔✔Explain moderate variability. amplitude range >25 BPM - ✔✔Explain marked variability. A compromised fetus. possible causes are severe fetal anemia from RH isoimmunization, massive feto-maternal hemorrhage, ruptured vasa previa, twin to twin transfusion, fetal intracranial hemorrhage. - ✔✔What does it mean to have an undulating FHR pattern? What are the causes of undulating patterns in FHR? Defined as having a smooth, sine wave-like undulating pattern in the FHR baseline with a cycle frequency of 3 - 5/min. that persists for at least 20 minutes. It DOES NOT represent variability. You usually see amplitudes of 5-15 BPM. You will not see any accelerations with the sinusoidal pattern. Decelerations with a sinusoidal pattern are an even more ominous sign. - ✔✔Explain sinusoidal pattern FHR. Absent-fluctuations in the FHR are not detectable. - ✔✔What is the variability? Minimal- Small fluctuations in the FHR, detectable but not more than 5 BPM - ✔✔What is the variability? Moderate-note the span of the fluctuations in the baseline FHR. They are 10-20 BPM in height. The range of moderate variability is 6-20 BPM - ✔✔What is the variability? Marked- note the wide span of the fluctuations in the baseline FHR. In this case the fluctuations are >25BPM.
- ✔✔What is the variability? Can be a sign of inadequate oxygenation, may indicate a fetal central nervous system or cardiovascular anomaly, or may indicate a pre-existing fetal brain injury. May also result from maternal medications such as mag sulfate or narcotics. - ✔✔What does the absence of variability suggest?
An increase in variability from moderate to marked may indicate early stages of fetal hypoxemia or can be normal. Therefore baseline is a key assessment. - ✔✔What does marked variability suggest? Moderate variability shows intact neurological modulation of the FHR, normal cardiac responsiveness, and fetal reserve. This predicts the absence of fetal metabolic acidemia at the time it is seen and indicates the fetus is well oxygenated. - ✔✔What does moderate variability suggest? Abnormal fetal acid-base status and possible hypoxemia or impending acidemia. This pattern requires prompt evaluation and intervention. - ✔✔What does persistent absent variability of the FHR in combination with recurrent late or variable decelerations or bradycardia suggest? Visually apparent abrupt increases from the onset of the acceleration to peak in <30 seconds in the FHR above baseline. They may be periodic (assoc. w/contractions) or episodic (not assoc. w/contractions) The peak must be >15 BPM and must last >15 seconds from onset to return to baseline. Before 32 wks gest. an acceleration is defined as >10 BPM and a duration of >10 seconds. - ✔✔Define accelerations in FHR Changes in the FHR from baseline. Can be periodic or episodic and are defined depending on their timing in relation to contractions. Classification of a tracing w/ decelerations depends on the the type and context of the tracing. They are quantified by depth and nadir in BPM(except transient spikes or electronic artifact). The duration is quantified in minutes and seconds from beginning to end of the deceleration. - ✔✔Define decelerations of the FHR. Recurrent decelerations that occur with >50% of contractions in any 20 minute period. Intermittent decelerations occur with <50% of contractions in any 20 minute period. - ✔✔Explain recurrent and intermittent decelerations. Early Late Variable Prolonged - ✔✔Name the 4 types of decelerations of FHR
true - ✔✔True or False A preterm fetus my be more susceptible to hypoxemia true - ✔✔True or False The nervous system is not fully developed in fetuses prior to 32 wks gest.
- Higher baseline FHR i.e. a 23 wk gest may have a baseline of 155 BPM but at term, the same baby may have a baseline of 130 BPM. Any baseline above 160 BPM is still considered tachycardia.
- Decreased variability bc the central nervous system is not fully developed, variability may be decreased.
- lower amplitude accels in preterm (before 32 wks) accels of at least 10 BPM above baseline for at least 10 sec is acceptable.
- more frequent occurrences of variable decels - ✔✔What are the different characteristics of a fetus prior to 32 wks gest. than a term fetus? When information can not be obtained by palpation or use of toco and if there are no contraindications to its use. i.e. increasing oxytocin w/ elevated BMI if contractions are not being detected using toco. - ✔✔When should an IUPC (intrauterine pressure catheter) be placed? The primary obstetric provider. - ✔✔Who may insert an IUPC? Ultrasound monitors externally FHR. Fetal Spiral Electrode (FSE) monitors internally FHR. Tocodynamometer (TOCO) monitors externally contractions.
Intrauterine pressure catheter (IUPC) monitors internally contractions. - ✔✔Name several techniques/devices of fetal monitoring. External- Doppler ultrasound transducer (converts movement into sound to tracing on paper) Tocodynamometer (TOCO) monitors externally contractions. Internal- Fetal Spiral Electrode (FSE) monitors internally FHR. Intrauterine pressure catheter (IUPC) monitors internally contractions. - ✔✔Identify the 4 types of electronic instrumentation used to assess FHR and uterine activity. If the reflecting surface is moving the reflected signal has a frequency change known as a doppler shift. If the reflecting surface is moving toward the signal source the frequency of the signal increases; if the frequency decreases the surface is moving away. The back and forth movement of the fetal myocardium will produce an alternately higher and lower frequency. Stationary surfaces undergo no frequency change. The US ignores all reflected signals that have the same frequency as the transmitted signal. Those signals that have undergone a frequency change - a Doppler shift- are converted into electronic signals. - ✔✔Explain the principles of the Doppler shift as related to FHR monitoring.
- Performing Leopold's maneuvers.
- Applying the conduction gel.
- Securing the ultrasound.
- Reading the FHR tracing. - ✔✔List the 4 steps in using the external ultrasound device. Assess fetal lie, presentation, position and descent by abdominal palpation. This includes 4 maneuvers to assess the fetal part in the upper uterus, location of fetal back, presenting part and descent of the presenting part. - ✔✔What are Leopold maneuvers are used to determine?
Advantage- FSE is only direct means of assessing the FHR. Limitations- *Most will not record R-R intervals (FHR) greater than 240 BPM *Maternal pacemaker may interfere. *Requires ROM and dilated cervix. *May measure maternal heart rate in case of fetal demise. *small possibility of electronic interference and artifact although less than with external ultrasound. - ✔✔List advantages and limitations of the FSE. Contraindications- Maternal infections like HIV, Hepatitis or GBS +, complete placenta previa, undiagnosed vaginal bleeding, do not place FSE on face, fontanels or genitalia. - ✔✔Discuss contraindications for use of the FSE.
- Presentation (at the inlet of the pelvis)-palpate fundus if head is at fundus.
- Position/lie (relationship of the presenting part to the pelvis anterior, posterior or transverse) and (long axis, fetal spine long smooth hard plane longitudinal, transverse or oblique.)
- Descent (floating or engaged) grasp abd. above symphysis pubis note contour, size, consistency of presenting part. Head is firm, globular, mobile if unengaged and immoble if engaged. Breech is smaller, softer and irregular.
- Prominence of the head over the pelvic brim. Press in direction of the pelvic inlet for cephalic prominence. If prominence is on opposite of fetal back is likely the forehead and is in vertex or well tucked position. - ✔✔Describe the the 4 maneuvers of Leopold's maneuvers. Auscultate to confirm FHR. Turn off artifact elimination switch per manufacturers instructions. Check ECG cable and leg plate using self test per manufacturer. Check placement may be dislodged or attached to cervix instead of fetus. If none of the above works than apply new FSE or monitor by other means (US or auscultation) - ✔✔Explain how to trouble shoot an FSE that shows intermittent makings on the tracing rather than a continuous line. Maternal pulse detected
Intermittent markings There is no problem Turn off logic switch, check circuitry by a self test, check electrode placement, confirm FHR by auscultation - ✔✔What the possible cause for the problem with this tracing? Maternal pulse detected There is no problem The FHR is abnormally low. Confirm maternal pulse by palpation and replace FSE. OR It is possible the fetus is bradycardic. - ✔✔What the possible cause for the problem with this tracing? Maternal pulse detected Intermittent markings There is no problem - ✔✔What the possible cause for the problem with this tracing? Contractions by detecting abdominal wall contour changes. The device converts this to electronic impulses that register and print out on paper. Toco does NOT quantify resting tone or intensity of contractions. Changes of the abd wall can be caused by a number of events besides contractions (mat. respirations, pushing, vomiting, seizures, fetal activity and movement). A normal contraction creates a smooth and even fall on the tracing - ✔✔What does the Tocodynamometer measure? a. Uterine contraction wave form normal b. Maternal respiration c. Valsalva maneuver or pushing d. Maternal activity such as vomiting or seizure e. Fetal movement/activity
f. Maternal position change or sudden baseline shift g. Obscured or low baseline setting h. Inverted waveform r/t placement of toco - ✔✔Identify the uterine contraction variation: a. Uterine contraction wave form normal b. Maternal respiration c. Valsalva maneuver or pushing d. Maternal activity such as vomiting or seizure e. Fetal movement/activity f. Maternal position change or sudden baseline shift g. Obscured or low baseline setting h. Inverted waveform r/t placement of toco - ✔✔Identify the uterine contraction variation: a. Uterine contraction wave form normal b. Maternal respiration c. Valsalva maneuver or pushing d. Maternal activity such as vomiting or seizure e. Fetal movement/activity f. Maternal position change or sudden baseline shift g. Obscured or low baseline setting h. Inverted waveform r/t placement of toco - ✔✔Identify the uterine contraction variation: a. Uterine contraction wave form normal b. Maternal respiration c. Valsalva maneuver or pushing d. Maternal activity such as vomiting or seizure e. Fetal movement/activity
f. Maternal position change or sudden baseline shift g. Obscured or low baseline setting h. Inverted waveform r/t placement of toco - ✔✔Identify the uterine contraction variation: a. Uterine contraction wave form normal b. Maternal respiration c. Valsalva maneuver or pushing d. Maternal activity such as vomiting or seizure e. Fetal movement/activity f. Maternal position change or sudden baseline shift g. Obscured or low baseline setting h. Inverted waveform related to placement of toco - ✔✔Identify the uterine contraction variation: Advantages- it is external so it is non invasive and ROM is not necessary Limitations- it is location sensitive so improper placement or movement can cause uninterpretable tracing. It is not a means of assessing true resting tone or intensity so must use in conjunction with direct palpation. Toco only gives an approximate measure of duration and frequency. Reading can vary greatly based on mat. weight, mat. position, and position of belt. - ✔✔What are the advantages and limitation of Toco? top center is where you should receive the most accurate reading of uterine contractions as term. - ✔✔Select the best location for placement of Toco for a term pregnancy. It is the only method that directly measures the uterine resting tone, contraction intensity, frequency and duration. It is an invasive procedure that requires ROM and cervical dilation. IUPC is used when there is a need for more detailed information than palpation or toco can provide. The IUPC measures hydrostatic pressure in the uterus, measuring intrauterine pressure during and between contractions. - ✔✔What is an Intrauterine pressure catheter (IUPC) and what does it measure?
- When labor and not progressing & assessment of the adequacy of the contraction is needed.
