Relias - Fetal Heart Monitoring Questions and Answers 2023 1. A deceleration that begins after the onset of a uterine contraction, reaches its nadir (lowest point) after the peak of the contraction and takes at least 30 seconds to reach its lowest p

Relias - Fetal Heart Monitoring Questions and Answers 2023 1. A deceleration that begins after the onset of a uterine contraction, reaches its nadir (lowest point) after the peak of the contraction and takes at least 30 seconds to reach its lowest p 1. uterine blood supply: - uterine arteries deliver oxygenated blood to spiral arteries which bring oxygen rich blood to intervillous space of placenta that has fetal capillaries - fetal capillaries carry the O2 rich blood to umbilical VEIN that goes to fetus -in contrast, the umbilical ARTERIES return waste products to that intervillous space that go into mother's venous system 2. Potential issues that negatively affect fetal oxygenation: *Maternal Oxygenation:* asthma, hyper- or hypo- ventilation *Maternal Circulation:* decreased maternal cardiac output, hypotension, decreased Hgb *Placental O2 and CO2 Exchange:* postterm, abruption, HTN, hypotension, uterine tachysystole *Fetal circulation:* cord compression or occlusion 3. Fetal hypoxemia: - can occur d/t reduced fetal O2 reserves, excessive uterine activity, or reduced uteroplacental blood flow - worsening fetal hypoxemia can lead to abnormal FHR patterns, mostly minimal or absent variability from acidemia 4. (1) hypoxemia vs. (2) hypoxia: 1 - reduce O2 in blood 2 - reduced O2 delivery at tissue level 5. Fetal anaerobic metabolism: - occurs when long term O2 delivery is insufficient to meet cellular needs of tissues - results in production of lactic acid and other noncarbonic acids - ACIDOSIS is the presence of excessive acids in tissues 6. acidosis: pH below 7.35 pH is low Relias - Fetal Heart Monitoring STUDY GUIDE 2 / 10 (acidosis is the process that leads to low blood pH, or acidemia) 7. alkalosis: pH above 7.45 pH is high 8. buffers: - help maintain acid base homeostasis - 2 major fetal buffers are plasma bicarbonate and hgb 9. base excess and base deficit: - base deficit is expressed as a positive number - base excess is expressed as a negative number ~ they are equivalent and terms are used interchangeably ~ 10. fetal acidosis: - when O2 is decreased to fetus, tissue hypoxia results in acidosis, which then shows a drop in pH, a loss of bicarb, and increase in base deficit 11. acidemia: assoc w/ widespread, deleterious effects on vital organ and body function 12. fetal hypoxia during birth: assoc w/ neonatal depression, low apgars, neonatal encephalopathy, and cerebral palsy 13. respiratory acidosis: *low pH ( 7.10), high pCO2 ( 60), normal base deficit ( 12)* - increase of pCO2 for fetus that lowers pH but doesn't affect base deficit 14. factors that contribute to resp acidosis: - sudden decrease in placental or cord perfusion - uterine tachysystole - maternal hypoventilation 15. metabolic acidosis: *ph 7.10 , normal pCO2 (60), high base deficit (12)* - a higher base deficit (such as 12) has been assoc w/higher risk for severe neonatal complications - most common cause of metabolic acidosis in fetus is r/t inadequate O2 delivery 3 / 10 - prolonged hypoxic insult to fetus results in depletion of bicarb, which is a base buffer that normalizes pH levels 16. mixed acidosis: *pH 7.10 , high pCO2 60, and high base deficit 12* - may develop when resp acidosis persists for a prolonged period of time -outcome for neonates is dependent on degree and severity, but typically the lower pH and higher base deficit means worse neonatal outcomes - most often seen in prolonged bradycardia at time of birth 17. what is used to evaluate fetal acidosis?: arterial umbilical cord blood 18. artery values (fetus to placenta): Normal ranges: pH 7.20-7.28 pCO2 35-70 Base excess -3 to -9