Fhr - freeman

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Fetel Heart Rate Monitoring

Chapter 2 - Physiology Mean Art Pressure = 85mmhg Intramyometrial Pressure = 10mmhg amniotic fluid pressure = 10mmhg contraction = 120mmhg factors that affect: surface area, anesthesia, HTN (decreased via acute spastic or chronic atheramatous), diffusion distane ie thickness (erythroblastosis w/ placenta edema / diabetics)

variable decel - -w/ severe hypoxemia & fetal metabolic acidosis there may be a delayed deceleration component due to hypoxic myocardial depressio -FHR & FSBP = fig 2.10 venous occlusion -> decreased preload -> decrease fetal cardiac output and increase fetal heart rate. blood flow going to placenta obstructed, increase in fetal BP and fetal HR slows as result of increasedd periph. vascular resistance. oligo may be associated with variables before labor.

late decel-late decel is primarily a reflex change with nonacidemic hypoxia, but when hypoxia is severe enough to result in acidemi, the mechanism appear to be nonreflex or direct myocardial depression. FSE may be of value to determine whether late decel is occuring in association with acidemia

variabilityparasymp=short, symp=longer. 1) earliest effect of fetal hypoxemia - increase in both long/short term variability (adrenergic discharge / fetal HTN)prolong = decrease FHR variability likely d/t hypoxia or acidosis.sinusoidal - chronic fetal anemia, Erythroblastosis, acute intrapartum event, FM-Hemorrhage

    • Early hypoxia (UPI or cord compression) fhr are primarily neural reflex, whereas severe hypoxia and fetal acidosis are prob d/t myocardial depression**

accel-scalp stim is reassuring against acidosis / fetal depression

Chapter-3 Neonatal Encephalopathyfever, prolong rupture of membranes, thick mec, malposition, intrapartum hypoxia, acute intrapartum event, forceps or ER C/S.

criteria for acute intrapartum asphyxia as a cause of neonatal brain damage. must meet all 4 1. evidence of metabolic acidosis in fetal umb cord artery @ deliv (ph<7 and base def >12mmol/l) 2. early onset of severe or moderate neonatal enceph. in infants born @34 wks or more 3. CP of spastic quadriplegic or dyskinetic type 4. exclusion of other etioligies such as trauma, coagulation d/o, infectious conditions, or genetic disorders

suggestive: sentintel hypoxic event occuring near labor, sudden/sustained fetal bradycardia or absense of FHR variability in presense of persistent late or variable decels, usually after a hypoxic sentinel event. apgar of 0 to 3 beyond 5 min. multisystem involvement within 72hrs of life, early imaging showing evidence of acute nonfocal cerebral abnl.

Chapter-6 basic pattern recognition NICHD 2008 Terminology Cat 1 - Normal FHR pattern 110-160, moderate (5-25) varibility, late and varaible decel abset, early present or abset, accel present or absent.

cat 3 - absent FHR variability and recurrent late, recurrent variable, bradycardia, sinusoidal.

Cat 2 - type in later.

Late Decel 1. size of late decel may correlate to degree of hypoxia, but not always! 2. persistent lates are significant and potentially ominous 3. the association of Lates with loss of variaibility and elevation of baseline FHR is more significant than decel alone and reflects fetal intolerance to hypoxic stress

Variable Decel 1. Early labor - usually oligo as a cause & likely not repsond to position change, try amnioinfusion 2. 2nd stage of labor - cord stretch/compression. 3. cord prolapse 4. unsual causes - true knot, limb entangelment, short cord.

grades mild <30sec, regardless of level or a decel not below 70 to 80, regardless of duration moderate have a level <80bpm, regardless of duration severe <70bpm for >60 sec. (also tachycardia to 80-90bpm are severe) slow return to baseline is a sign fetus is not tolerating the intermittent cord compression if slow return is preceded by late or severe variables, then it is a sign of progressive hypoxia, if neither - then slow return to baseline is NOT a predictive factor. Overshoot lasting >1 min as gradual, smooth accel usually seen in flat baseline.

Reflex variable decels do not suggest fetal hypoxia when 1) the decel lasts <30-45 sec., 2) there is a rapid return to baseline from nadir of decel, 3) moderate variability of baseline FHR is present and 4) baseline rate is not increasing.(variables viewed as reflex or indicating developing fetal hypoxia. Variables suggestive of hypoxia - become deep & long lasting with delayed return to baseline w/ or w/o overshoot with decreasing baseline variability or increasing baseline ---If loss of variability and an increasing baseline develop with more severe 2nd stage variable decels, expeditious delivery is warranted--

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