NM704 Exam 2: Thorough Questions And Detailed
Solutions
Baseline HR: Right Ans - -Approximate mean FHR during a 10 minute
period
-Normal is 110-160 bpm
Fetal bradycardia: Right Ans - -HR less than 110 for at least 10 minutes
Fetal tachycardia: Right Ans - -HR greater than 160 for at least 10 minutes
FHR variability: Right Ans - -fluctuations in the FHR baseline that are
irregular in amplitude and frequency
-minimal (0-5 bpm)
-moderate (6-25 bpm)
-marked (>25 bpm)
Absent variability: Right Ans - -absent (undetectable)
-this is the RED zone
Minimal variability: Right Ans - -0-5 bpm variation
Moderate variability: Right Ans - -6-25 bpm variation
-this is the GREEN zone!
Marked variability: Right Ans - >25 bpm variability
-this can be indicative of a brief period of hypoxia, however it is not associated
with adverse neonatal outcomes
Tachysystole Right Ans - -more than 5 contractions in 10 minutes averaged
over 30 minutes
FHR acceleration: Right Ans - -ABRUPT increase in heart rate by 15 bpm
above the baseline that lasts for at least 15 seconds but less than 2 minutes
-10X10 used for less than 32 weeks*
, FHR early deceleration: Right Ans - -gradual decrease in FHR that begins
with the onset of a contraction and comes back up with the end of the
contraction
-"mirror image"
FHR late deceleration: Right Ans - -gradual decrease in FHR that begins
after the peak of a contraction and does not come back up until after the
contraction is over
-delayed in timing*
FHR variable deceleration: Right Ans - -ABRUPT decrease and subsequent
increase in heart rate that can be with or without a contraction
-V or W shaped
-can be shallow or deep
FHR prolonged deceleration: Right Ans - -gradual decrease in heart rate
that remains down for more than 2 minutes but less than 10 minutes
What is the sympathetic input for the FHR? Right Ans - -fibers in the fetal
heart muscle respond to catecholamines which in turn increase the heart rate
-can be demonstrated by vibroacoustic stimulation or fetal scalp stimulation*
What is the parasympathetic input for the FHR? Right Ans - -mediated by
the vagus nerve
-parasympathetic system matures in the 2nd trimester and gradually
dominates over the sympathetic system
-a lower baseline closer to term is indicative of a MATURE parasympathetic
system
How do chemoreceptors play a role in FHR? Right Ans - -sensitivity of
chemoreceptors to changes in oxygen and CO2
-when low oxygen and high CO2 is detected the sympathetic system is
stimulated to redirect blood flow to vital organs and parasympathetic is
stimulated to slow HR in order to decrease work of the heart with minimal
oxygen
How do baroreceptors play a role in FHR? Right Ans - -detects change in BP
-if higher BP is detected vagal stimulation will slow the HR
-if lower BP is detected sympathetic stimulation will increase the HR
Solutions
Baseline HR: Right Ans - -Approximate mean FHR during a 10 minute
period
-Normal is 110-160 bpm
Fetal bradycardia: Right Ans - -HR less than 110 for at least 10 minutes
Fetal tachycardia: Right Ans - -HR greater than 160 for at least 10 minutes
FHR variability: Right Ans - -fluctuations in the FHR baseline that are
irregular in amplitude and frequency
-minimal (0-5 bpm)
-moderate (6-25 bpm)
-marked (>25 bpm)
Absent variability: Right Ans - -absent (undetectable)
-this is the RED zone
Minimal variability: Right Ans - -0-5 bpm variation
Moderate variability: Right Ans - -6-25 bpm variation
-this is the GREEN zone!
Marked variability: Right Ans - >25 bpm variability
-this can be indicative of a brief period of hypoxia, however it is not associated
with adverse neonatal outcomes
Tachysystole Right Ans - -more than 5 contractions in 10 minutes averaged
over 30 minutes
FHR acceleration: Right Ans - -ABRUPT increase in heart rate by 15 bpm
above the baseline that lasts for at least 15 seconds but less than 2 minutes
-10X10 used for less than 32 weeks*
, FHR early deceleration: Right Ans - -gradual decrease in FHR that begins
with the onset of a contraction and comes back up with the end of the
contraction
-"mirror image"
FHR late deceleration: Right Ans - -gradual decrease in FHR that begins
after the peak of a contraction and does not come back up until after the
contraction is over
-delayed in timing*
FHR variable deceleration: Right Ans - -ABRUPT decrease and subsequent
increase in heart rate that can be with or without a contraction
-V or W shaped
-can be shallow or deep
FHR prolonged deceleration: Right Ans - -gradual decrease in heart rate
that remains down for more than 2 minutes but less than 10 minutes
What is the sympathetic input for the FHR? Right Ans - -fibers in the fetal
heart muscle respond to catecholamines which in turn increase the heart rate
-can be demonstrated by vibroacoustic stimulation or fetal scalp stimulation*
What is the parasympathetic input for the FHR? Right Ans - -mediated by
the vagus nerve
-parasympathetic system matures in the 2nd trimester and gradually
dominates over the sympathetic system
-a lower baseline closer to term is indicative of a MATURE parasympathetic
system
How do chemoreceptors play a role in FHR? Right Ans - -sensitivity of
chemoreceptors to changes in oxygen and CO2
-when low oxygen and high CO2 is detected the sympathetic system is
stimulated to redirect blood flow to vital organs and parasympathetic is
stimulated to slow HR in order to decrease work of the heart with minimal
oxygen
How do baroreceptors play a role in FHR? Right Ans - -detects change in BP
-if higher BP is detected vagal stimulation will slow the HR
-if lower BP is detected sympathetic stimulation will increase the HR
