Advanced Fetal Monitoring Exam 2024

Cat 1 - What category rules out fetal acidemia? Severe astha, cardiac issues, and ecclampic seizures - What maternal conditions greatly impact fetal oxygenation? intervillous space - Where does the exchange of O2 and nutrients take place? O2 enters the intervillous space via the maternal arteries, to the villi then the umbilical vein take the o2 blood to the fetus. The umbilical arteries take the deO2 blood from the baby through the villi and back to the mother - How is o2 blood transferred to the fetus? High to low concentration Mom to fetus for O2 Low to high concentration for CO2 so baby to mom - Diffusion Diffusion - How is O2 transferred from mom to baby Carry O2 into intervillous space Are maximally dilated so they can not be increased - Explain spiral arteries in placenta Maternal conditions like pre-e and cardiac disease Maternal hypotension Placental changes- abruptions, infections, edema, or smaller size Excessive uterine activity Vasoconstriction - What are factors that can decrease uteroplacental blood flow? They are constricted which decreases blood flow - What happens to the spiral arteries during pre-e? The aorta and vena cava get compressed (20 weeks) - Why does the supine position cause decreased uteroplactenal blood flow? Blocks the sympathetic pathway Pooling of blood in the lower extremities decreases blood flow back to moms heart which decreases blood flow to the fetus - Why does maternal hypotension happen after regional analgesia? 60% - What percentage is uteroplacental blood flow decreased by during cxts? Environment to lungs to heart to vasculature to uterus to placenta to umbilical cord - Explain the pathway for maternal- fetal exchange for fetal oxygenation (basic) Limbs, kidneys, and descending aorta - Where is the least O2 blood in the fetus? Umbilical vein and ductous venous - Where is the most O2 blood in the fetus? Ductus venosus - Connects the umbilical vein to the inferior vena cava, bypassing the liver Shunt that allows most O2 blood to fetal heart ductus venosus, foramen ovale, ductus arteriosus - 3 important shunts in fetal circulation Foramen Ovale - connects the two atria in the fetal heart Allows O2 blood to flow through the heart and directly to the brain Ductus Arteriosus - a blood vessel in a fetus that bypasses pulmonary circulation by connecting the pulmonary artery directly to the ascending aorta 80-100 mL/kg - What is a normal blood volume for a fetus at term? Increased heart rate - What happens if you stimulate the sympathetic nervous system? Regulates the sympathetic - What does the parasympathetic nervous system do? Increased heart rate - What happens when catecholamines (sympathetic) get released? The sympathetic develops first so there is no parasympathetic to regulate the heart rate - Why do pre-termers have increased heart rates? Acetylcholine is released which decreases the intrinsic heart rate Vagus stimulation - What happens when the parasympathetic nervous system is stimulated? Protect Regulates BP - What do baroreceptors do? Decreased FHR, BP and CO - What effect do baroreceptors have on the fetus? The cord gets compressed and then fetal BP increased which triggers baroreceptors that decreased the FHR which produces a variable - What happens when there is cord compression (in regards to baroreceptors)? Variables - What decels relate to baroreceptors? Lates - What decels relate to chemoreceptors? Increased PCO2 Decreased PO2 and pH - What action takes place when chemoreceptors are stimulated? Bradycardia and hypertension - What effect do chemoreceptors have? Decreased or absent variability - The stoke volume does not fluctuate - What differs in fetal CO from adult CO? The CO decreases which leads to hypoxia and acidemia - What happens when the fetal heart decreases (in regards to CO)? 51-56% - What is the fetal Hct? Increased Hct Fetal Hbg has a higher affinity for O2 Fetal HR and CO is increased which results in rapid circulation of O2 blood - What are 3 fetal physiologic adaptations from the mother? Increased blood flow to vital organs (heart, brain, adrenals) Decreased blood flow to spleen, kidneys, and limbs FHR slows and myocardium decreases O2 consumption - What is the fetal response to acute hypoxia anaerobic metabolism - The metabolism that takes place in the absence of oxygen; the principle product is lactic acid. Aerobic metabolism with O2 then there's hypoxemia (decrease in O2) which leads to tissue hypoxia. The body is forced to resort to anaerobic metabolism which leads to a buildup of lactic acid in the blood. This then causes metabolic acidosis (causes cellular death). - Explain the oxygenation depletion cascade 60-90 minutes - How one does it take for significant acidemia to take place? Adrenergic activity - What is marked variability mediated by? Opioids, magnesium, and tobacco (medications or drugs) Fetal sleep cycles Fetal acidemia- there will be no accels here - What are things that can cause decreased variability? 10x10 - What accelerations do gestations less than 32 weeks need? Fetal head compression leads to altered cerebral blood flow which produces a vagabond reflex and cardiac slowing - Describe the reasoning for early decels Uteroplacental insufficiency results in decreased maternal/fetal O2 transfer - Describe the physiology of a late decel It's neurogenic Exclude clinically significant acidemia Provide interventions to increase perfusion - What do late decels with moderate variability mean and indicate? Means myocardial depression Expedited delivery - What do late decels with decreases variability mean and indicate? Interruption of uteroplacental perfusion or exchange- tachysystole, maternal hypotension, maternal hypoxia (seizure or cardiac arrest), placental abruption, or uterine rupture Interruption of umbilical blood flow- cord compression, cord prolapse, or ruptured vasa previa - What are 3 causes of prolonged decels? Vasa previa - Presence of fetal (not placental) blood vessels that cross the internal cervical os (marginal or velamentous cord insertions or with succenturiate lobes). Umbilical cord crosses the internal cervial os parasympathetic nervous system - What nervous system has control over bradycardia? Fever Dehydration Infection Medications- terbutaline, albuterol, atropine, cocaine, or caffeine Medical conditions- hyperthyroidism - What are some maternal conditions that can lead to fetal tachycardia? Fetal bleeding- placental abruption Fetal anemia Fetal sepsis Fetal hypoxia Arrhythmias - What are some fetal conditions that can cause tachycardia? Severe fetal anemia- ruptured vasa previa, TTTS, Rh isoimmunization Severe metabolic acidemia - What are causes of sinusoidal pattens? Every 30 mins - How often do you chart heart tones for a low risk pt from latent phase up to the 2nd stage (until pushing)? Ever 15 mins - How often do you chart heart tones from the latent phase up until the second stage of labor with a high risk patient? 2 to 4 mu - At what rate is exogenous oxytocin at for the mother during the first stage of labor?