Fetal Heart Monitoring Lecture Powerpoint Flashcards
2 methods to monitor the fetal heart rate
- auscultation
- electronically (nowadays this is the most common obstetrical procedure reviewed frequently thru the first and 2nd stages of delivery)
Methods of external fetal heart rate monitoring electronically (2)
- ultrasound doppler with gel held in position by belt (not as strong)
- internal FHR monitoring, a bipolar electrode attached to fetal scalp with a wire penetrating the scalp (membranes are ruptured) where a 2nd pole is the metal base of the electrode and vaginal fluid creates saline electric bridge (requires intact maternal physiology, functional placenta, and fetus)
Insufficient o2 or nutrition (chronic, long term malnutrition) in the mother can cause these things (5)
- intrauterine growth restriction
- hypoxia
- metabolic acidosis
- acute aspyxia
- fetal death
Placenta function can be chronically impaired by these things (5)
- hypertension
- pre-eclampsia
- type 1 diabetes
- Rh sensitization
- intrauterine growth restriction
Placenta function can be acutely impaired by these things (3)
- placental separation
- placental infarct
- maternal or fetal hypotension
Tachysystole (uterine activity)
More than 5 contractions in 10 min averaged over 30 minutes, should always be qualified as to the presence or absence of fetal heart rate abnormality
Basic warning signs in labor (4)
- contractions lasting longer than 90 seconds (starve fetus of oxygen and nutrients)
- relaxation between contractions of less than 60 seconds (if not at rest for long enough, not enough time to wash out co2 and gain o2 and nutrients)
- resting uterine tone above 20mmhg (normal is 5-10 mmHg, during labor may be 10-15)
- peak pressure of contractions above 90 mmHg
Normal fetal heart rate during development and at term
110-160bpm, until week 26 heart rate controlled by sympathetic NS, as matures parasympathetic increases in control slowing the heart to 110-120bpm
Tachycardia of fetal heart rate
Greater than 160bpm
Factors associated with fetal tachycardia (6)
- fetal/maternal temp elevation
- medication side effects
- acidosis
- arrhythmia
- hypovolemia
- hyperthyroidism
Factors associated with fetal bradycardia (4)
- post term fetus (mature parasympathetic system)
- hypoxia
- B blockers
- damage to fetal heart
Short term healthy variability in fetal heart rate
Should have amplitude ranging from 5-15 beats per minute indicates good autonomic interplay
Short term variability in the fetal heart rate below 5bpm may indicate (4)
- fetal sleep period
- CNS depression
- hypoxia
- drugs or maternal smoking
Response to decreased short term or long term variability in fetal heart rate (5)
- stimulate fetus
- attach scalp electrode for internal monitor
- check fetal pH
- change maternal position
- just deliver the damn thing
Long term variability in fetal heart rate
Variability in the baseline rate over a more extended period of time (1 min) usually amplitude of 3-25 bpm, decreased during sleep, drugs, hypoxia, and tachycardia and increased during hypoxia
Head compression
Predictable event as uterus compresses engaged head causing vagal slowing causing early decelaration of fetal heart rate and ends with same time as uterine contraction, NOT considered a sign of distress
Uteroplacental insufficiency
Predictable event as uterus compresses engaged head causing vagal slowing causing LATE decelaration of fetal heart rate in comparison to uterine contraction,
Response to uteroplacental insufficiency (late decelerations)
- change maternal position to side (prevent positional compression)
- stop oxytocin
- increase IV fluids
- o2 for mom up to 100%
Cord compression
Predictable event as uterus comresses the umbilical cord causing VARIABLE decelerations of fetal heart rate, most common, if prolonged causes hypoxia
Response to cord compression (variable decelerations) (4)
- change maternal position to right or left side
- 100% o2
- stop oxytocin
- deliver via forceps or c-section
Category 1-3 FHR tracings
Category 1 - normal, strongly predictive of normal fetal acid base status at delivery
Category 2 - Tracings are indeterminate, not predictive of abnormal fetal acid base status, require eval and continued surveillance and re-eval
category 3 - tracins are abnormal, associated with abnormal fetal acid base balance, requires prompt eval, maternal o2, change in position, etc
Category 1 FHR tracings characteristics
Baseline rate 110-160 Baseline variability: moderate Late or variable decelerations: absent Early decelerations: present or absent Accelerations: present or absent
Category 2 FHR tracings characteristics
Baseline rate: bradycardia or tachycardia without absent baseline variability
Baseline Variability: absent with no recurring decelerations, minimal, marked
Accelerations: absent or present after fetal stimulation
Category 3 FHR tracings characteristics
Category 3 tracings include absent baseline FHR variability and any of the following: Recurring late decelerations Recurring variable decelerations Bradycardia Sinusoidal pattern
Brain damage in labor determining factors (did it happen during labor and not beforehand?) (4)
- profound umbilical artery acidemia (pH <7)
- apgar score 0-3 for longer than 5 min
- neonatal neurological sequelae (seizures, coma, hypotonia)
- multiorgan system dysfunction
Fetal monitoring overreliance
Out of 1000 fetuses with appearing fetal distress on FHR tracing only 1-2 developed cerebral palsy, in other words we are over c-sectioning due to overreliance however it is better than auscultation technique in most and makes it easier on nurses so it is here to stay