Term
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Definition
| Increased hydrogen ions in tissue |
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Term
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Definition
| increased hydrogen ions in blood |
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Term
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Definition
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Term
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Definition
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Term
| which umbilical cord blood reflects fetal status? |
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Definition
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Term
| Fetal adaptive measures for low-O2 environment |
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Definition
- fetal blood has more hemoglobin than adult blood and higher affinity for O2 at the same partial pressures of O2
- fetal circulation "overperfuses" certain organs such as the brain
- fetus has more capillaries
- fetus has increased cardiac output
- fetus has higher heart rate
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Term
| what is the etiology of compromised oxygenation in the fetus during contractions? |
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Definition
| transient decrease in blood flow to the palcenta interrupts gas exchange across placent. Occlusion can impede circulation to and from the fetus then O2 content of fetal blood decreases (hypoxemia) and CO2 increases. If repetetive or prolonged, decreased O2 in fetal blood can lead to decreased O2 in tissues and possibly increased hydrogen ions (resp. acidemia). If this persists, fetus switches to anaerobic metabolism and lactic acid buildup (metabolic acidemia). |
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Term
| Define fetal respiratory acidemia |
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Definition
| low pH in the presence of significantly elevated PCO2 and normal bicarb |
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Term
| Define fetal metabolic acidemia |
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Definition
| low pH with normal PCO2 and low bicarb |
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Term
| Define fetal mixed acidemia |
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Definition
| bicarb is low and PCO2 is elevated (low pH) |
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Term
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Definition
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Term
| normal fetal arterial pCO2 |
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Definition
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Term
| normal arterial fetal PO2 |
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Definition
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Term
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Definition
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Term
| indications for collection of cord blood gases |
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Definition
- non-reassuring fetal heart rate
- meconium stained fluid
- need for infant resuscitation
- antepartum dx of IUGR
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Term
| frequency of IA according to ACOG and ACNM |
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Definition
- ACOG: active q 15 mins, 2nd stage: q5
- ACNM: active q 15-30, 2nd stage q5
- it is also recommended that FHR be assesed before or after SVE, ROM, medication administration or ambulation
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Term
| describe physiology of FHR variability |
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Definition
| vagus nerve receives incput from chemoreceptors, baroreceptors and CNS. Vagus nerve controls FHR through s-a node in heart and changes the time between the heart contractions as needed. the variation in time between each beat is seen as variability on EFM |
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Term
| describe early deceleration |
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Definition
- visually apparent gradual decrease and return to baseline with uterine contraction
- nadir of deceleration occurs at the same time as peak of contraction
- accompanied by moderate variability
- not seen with tachycardia, minimal or absent variability or recurrent late or early decelerations
- appear in early active labor for a short time, not usually seen in second stage
- not associated with a pattern evolution from moderate to minimal to absent variability
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Term
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Definition
uterine contraction->decreased uterine blood flow into intervillous space->decreased oxygen tension stimulates chemoreceptor->deceleration of FHR
- gradual decrease and return of FHR associated with UC
- the deceleration is delayed in timing with the nadir occurring after the peak of the contraction
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Term
| what are the two mechanisms for variable decelerations? |
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Definition
- neurogenic: head compression-> vagal stimulation->rapid drop in FHR
- cord occlusion (fetal BP rises)->baroreceptors stimulated->rapid drop in FHR
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Term
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Definition
| 5 or more contractions in 10 mins averaged over a 30- minute window |
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Term
| define minimal variability |
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Definition
from undetectable to 5 bpm
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Term
| define moderate variability |
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Definition
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Term
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Definition
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Term
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Definition
- visually apparent abrupt increase in FHR
- increase from onset of acceleration to peak in 30 secs
- must be 15 bpm and last 15 seconds
- prolonged acceleration is 2-10 minutes in duration
- acceleration lasting >10 mins is considered baseline change
- before 32 wks gestation, accelerations are 10 bpm for 10 seconds
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Term
| When should you worry about fetal acidemia? |
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Definition
- minimal or absent variability for an hour or more as solitarty finding not due to a known, benign cause such as maternal medication
- recurrent late decelerations or repetetive moderate to severe variables AND minimal or absent variability
- persistent tachycardia or bradycardia AND minimal or absent variability
- persistent or pregressive bradycardia below 80 bpms
- sinusoidal patterns
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Term
describe fetal scalp stimulation
what is the sensitivity and specificity? |
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Definition
- gentle stroking of fetal scalp for 15 seconds with fingers
- reactive if FHR rises by 15 bpm for 15 secs (negative for fetal acidemia)
- non-reactive if FHR fails to rise at all or less than 15 bpm for 15 secs (positive for fetal acidemia)
- sensitivity of non-reactive FSS for pH<7.2 is 40.7%
- specificity is 84.2%
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Term
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Definition
- baseline rate 110-160
- moderate variability
- absent late or variable decelerations
- present or absent early decelerations
- accelerations present or absent
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Term
| define Category II FHR tracings |
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Definition
- bradycardia not accompanied by absent baseline variability
- tachycardia
- minimal baseline variability
- absent baseline variability with no recurrent decelerations
- marked baseline variability
- absence of accelerations after FSS
- recurrent variable decelerations with minimal or moderate baseline variability
- prolonged deceleration > 2mins but < 10 mins
- variable deceleration with other characteristics ie: slow return to baseline, overshoots or "shoulders"
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Term
| define Category III FHR tracings |
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Definition
absent baseline variability with any of the following:
- recurrent late decelerations
- recurrent variable decelerations
- bradycardia
sinusoidal pattern |
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Term
| what are primary indications for amnioinfusion? |
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Definition
- cord compression may improve with restored AF
- mec-stained fluid may be diluted or rinsed away
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