Lecture 2 Flashcards
Pathological FHR decels share which common theme?
Disruption of normal pathway of O2 from environment to fetus
Principles of Fetal Monitoring
- Maternal vital signs (Physiologic basis for FHR)
- Oxygenation of maternal-fetal unit (Adequate oxygenation of mom = fetal tolerance of labor)
How many arteries and veins comprise the umbilical cord?
2 fetal arteries, 1 vein
Which leads to the heart in the fetus: Artery or Vein?
Vein
Artery means “away”: Arteries carry oxygen from the heart through the body
What serves as the fetal lung?
Placenta
Foramen Ovale
A hole btwn the atria that allows oxygen-rich blood to flow directly to the left atrium, down to the left ventricle, and out the aorta to the brain
Ductus Arteriosus
Allows blood to bypass the lungs by going directly from right atrium to right ventricle
Normal fetal hematocrit level
15g/dL
Definition of Hypoxemia
Decreased oxygen content in blood
Definition of Hypoxia
Decreased level of oxygen in tissue (r/t asphyxia)
Definition of Acidemia
Increased hydrogen ions in blood
Definition of Acidosis
Increased hydrogen ions in tissue (r/t asphyxia)
Definition of Asphyxia
Hypoxia with metabolic acidosis
2 Point of Contact for External Fetal Monitoring
- Tocotransducer
-> To monitor uterine contractions
-> Placed on fundus - Ultrasound transducer (FHR)
-> Placed lower down, by pelvic bone
Definition of Electronic Fetal Monitoring
Electronic method of providing a continuous visual record of the FHR and uterine activity
Information is recorded on graph paper or in archiving database system
Information is permanent part of the maternal medical record
Information is retrievable for litigation
How may bpm are counted between each vertical line on tracing paper?
10 bpm
How many seconds are counted btwn the vertical bold lines on tracing paper?
60 seconds
Definition of a normal HR in fetus
110-160 bpm
Definition of Tachycardia in fetus
Above 160 bpm for 10+ minutes
Definition of Bradycardia in fetus
Below 110 bpm for 10+ minutes
Baseline FHR
Rate in the absence of contractions or periodic changes
Approximate average FHR rounded to increments of 5 bpm during a 10 minute segment
Need 2 minute minimum within those 10 minutes
Causes of Tachycardia in FHR: Fetal Conditions
- Hypoxemia
- Anemia
- Sepsis
- Prematurity
- Cardiac dysrhythmias
- Congenital anomalies
Causes of Tachycardia in FHR: Maternal Conditions
- Fever
- Dehydration
- Sepsis
- Anxiety
- Thyroid disease
- Drug use
Causes of Bradycardia in FHR
- Maternal position (baby is laying on cord)
- Maternal hypotension
- Response to drug administration
- Prolonged maternal hypoglycemia
Definition of Variability
- The normal changes and fluctuations in the FHR over a period of time
- Significant indicator of fetal well being
- Sensitive to hypoxia and acidosis
- SHOULD BE WHAT YOU ASSESS FIRST
Levels of Variability
Marked: > 25 bpm range
Moderate: 6-25 bpm range
Minimal: ≤ 5 bpm range
Absent: undetectable range
Reasons for Minimal Variability
- Hypoxia/acidosis
- Drug effects
- Fetal sleeping
- Congenital anomalies
- Extreme prematurity
- Fetal tachycardia
- Other cardiac dysrhythmias
Reasons for Marked Variability
- Increased fetal movement
- Hypoxia
- Vaginal exam/Fetal stimulation
- Second stage/Pushing
What is an Acceleration?
Abrupt rises in FHR
Most common type of FHR changes
These are REASSURING!!
What is considered an acceleration?
At ≥ 32 weeks: 15 or more bpm above baseline for 15 seconds or more, but less than 2 minutes
Before 32 weeks: shorter height and duration
10 x 10
What is the chemical trigger for early decels? NCLEX
Baroreceptors and chemoreceptors
Early decels
Onset to nadir ≥ 30 seconds
Start to lowest point takes ≥ 30 seconds
Decrease and return to baseline FHR associated with uterine contractions
Generally seen with first stage of labor
Nadir of decels occur at same time as peak of uterine contraction
Duration is < 2 minutes
Mechanism of Early Decels
- Pressure on the fetal fontanel
- Increased intracranial pressure
- Dilation is often ~ 4 cm
What is the chemical trigger for Variable Decels? NCLEX
Baroreceptors
Variable Decels
- Abrupt decrease (onset to nadir < 30 seconds)
- Return to baseline FHR may or may not be associated with uterine contractions
- “Variable” onset
Qualifiers:
- Decrease of the FHR ≥ 15 bpm from baseline
- Duration ≥ 15 seconds
- Duration less than 2 minutes
- High BP within circulation drops HR
