Intrapartum Fetal Heart Rate Analysis 2009

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Intrapartum Fetal Heart Rate Analysis 2009

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Intrapartum Fetal Heart Rate Analysis 2009

  1. 1. <ul><ul><li>Chukwuma I. Onyeije, M.D. </li></ul></ul><ul><ul><li>Atlanta Perinatal Associates </li></ul></ul><ul><ul><li>Clinical Associate Professor </li></ul></ul><ul><ul><li>Morehouse School of Medicine </li></ul></ul><ul><ul><li>http://maternalfetalmedicineblog.com </li></ul></ul><ul><ul><li>http://onyeije.net/present </li></ul></ul>
  2. 4. Systemic Stimuli Transmitted via Placenta
  3. 10. <ul><li>Case Control Study: </li></ul><ul><li>More than 11,000 </li></ul><ul><li>pregnancies studied. </li></ul>
  4. 11. <ul><li>FHR Characteristics associated with an increased risk of cerebral palsy </li></ul><ul><li>1. Multiple late decelerations </li></ul><ul><li>2. Decreased beat-to-beat variability of the heart rate </li></ul>
  5. 14. NELSON, and Colleagues. NEJM; 1996
  6. 20. The impairment of the delivery of oxygen to the brain and vital tissues during the progress of labor.
  7. 22.
  8. 24. <ul><li>Hypertensive disorders </li></ul><ul><li>Preterm delivery </li></ul><ul><li>IUGR </li></ul>
  9. 25. <ul><li>Fetal Heart Rate evaluation has a high rate of false positives </li></ul><ul><li>Clinical management based soley on FHR to avoid asphyxia can result in more harm than good. </li></ul>
  10. 26. <ul><li>Many infants with cerebral palsy do not have have clinically apparent intrapartum abnormalities </li></ul><ul><li>Is there a way to improve FHR interpretation to improve perinatal outcome? </li></ul>
  11. 27. Macones GA, Hankins GD, Spong CY, Hauth J, Moore T. The 2008 National Institute of Child Health and Human Development workshop report on electronic fetal monitoring: update on definitions, interpretation, and research guidelines. Obstet Gynecol 2008;112:661–6.
  12. 28. <ul><li>Review and update definitions of FHR patterns </li></ul><ul><li>Evaluate existing classification systems for FHR </li></ul><ul><li>Make recommendations for research priorities </li></ul>
  13. 29. <ul><li>BACKGROUND CLINICAL INFORMATION </li></ul><ul><li>NATURE / PRESENCE OF CONTRACTIONS </li></ul><ul><li>BASELINE FHR </li></ul><ul><li>FHR VARIABILITY </li></ul><ul><li>PRESENCE OF ACCELERATIONS </li></ul><ul><li>PRESENCE OF DECELERATIONS </li></ul><ul><li>CHANGES IN FHR OVERTIME. </li></ul>
  14. 30. Number of contractions in a 10 minute window averaged over a 30 minute window.
  15. 31. <ul><li>FHR: PATIENT A </li></ul><ul><ul><li>5 ctx per 10 min </li></ul></ul><ul><ul><li>4 ctx per 10 min </li></ul></ul><ul><ul><li>6 ctx per 10 min </li></ul></ul><ul><li>TOTAL =15 ctx in 30 min </li></ul><ul><li>ANSWER: 15 ∕ 3 ═ </li></ul><ul><li>5 ctx per 10 min </li></ul><ul><li>FHR: PATIENT B </li></ul><ul><ul><li>2 ctx per 10 min </li></ul></ul><ul><ul><li>0 ctx per 10 min </li></ul></ul><ul><ul><li>4 ctx per 10 min </li></ul></ul><ul><li>TOTAL =6 ctx in 30 min </li></ul><ul><li>ANSWER: 6 ∕ 3 ═ </li></ul><ul><li>2 ctx per 10 min </li></ul>
  16. 32. ACTIVITY CLASSIFICATION Contractions per 10 min Normal Activity Five or Less TACHYSYSTOLE More than 5 HYPERSTIMULATION No Longer Valid HYPERCONTRACTILITY No Longer Valid
  17. 33. <ul><li>DURATION of contractions </li></ul><ul><li>INTENSITY of contractions </li></ul><ul><li>RELAXATION time between contractions </li></ul><ul><li>A normal fetus can withstand the stress of labor without suffering from hypoxia because sufficient oxygen exchange occurs during the interval between contractions. </li></ul><ul><li>A fetus whose oxygen supply is marginal cannot tolerate the stress of contractions and will become hypoxic. </li></ul>
  18. 34. <ul><li>Fetal heart rate </li></ul><ul><li>Meconium </li></ul><ul><li>Fetal blood sampling </li></ul><ul><li>Umbilical cord blood sampling </li></ul><ul><li>The Apgar scoring system </li></ul><ul><li>Contraction stress test </li></ul><ul><li>Ultrasonic assessment </li></ul><ul><li>Biophysical profile testing </li></ul>Other Ways to Evaluate a Fetus During Labor
  19. 35. <ul><li>Auscultation of the fetal heart :by stethoscope or Doppler probe </li></ul><ul><li>Continuous Electronic fetal monitoring </li></ul><ul><li>External monitoring </li></ul><ul><li>Internal monitoring </li></ul>
  20. 36. Macones GA, Hankins GD, Spong CY, Hauth J, Moore T. The 2008 National Institute of Child Health and Human Development workshop report on electronic fetal monitoring: update on definitions, interpretation, and research guidelines. Obstet Gynecol 2008;112:661–6.
  21. 38. <ul><li>Fetal Heart Rate (in beats per minute) </li></ul>Rate Beats/min Normal 120-160 Tachycardia >160 Bradycardia <120
  22. 39. <ul><li>Baseline variability </li></ul><ul><ul><li>Short-time variability /beat-to-beat variability : short-term variability reflects the interval between either successive fetal electrocardiogram signals or mechanical events of the cardiac cycle </li></ul></ul><ul><ul><li>Long-term variability :Long-term variability reflects the frequency and amplitude of change in the baseline rate </li></ul></ul>
  23. 40. <ul><li>Normal short-time variability fluctuates between 5 and 25 bpm </li></ul><ul><li>Variability below 5 bpm is considered to be potentially abnormal </li></ul><ul><li>When associated with decelerations a variability of less than 5 beats/minutes usually indicates severe fetal distress </li></ul>
  24. 41. <ul><li>The normal long-term variability is 3 to 10 cycles per minute. </li></ul><ul><li>Variability is physiologically decreased during the state of quiet sleep of the fetus,which usually lasts for about 25 minutes until transition occurs to another state. </li></ul>
  25. 42. Short-time variability beat-to-beat variability Long-term variability
  26. 43. <ul><ul><li>No change : The FHR maintains the same characteristics as in the preceding baseline FHR. </li></ul></ul>
  27. 44. <ul><ul><li>Acceleration : The FHR increases in response to uterine contractions. this is normal response. </li></ul></ul>
  28. 45. <ul><li>Deceleration : The FHR decreases in response to uterine contractions. Decelerations may be early, late, variable or mixed . All except early decelerations are abnormal. </li></ul>
  29. 46. <ul><li>Baseline rate 110-160 bpm, </li></ul><ul><li>Moderate variability, </li></ul><ul><li>Absence of late, or variable decelerations, </li></ul><ul><li>Early decelerations and accelerations may or may not be present. </li></ul>
  30. 48. <ul><li>Baseline rate </li></ul><ul><ul><li>Bradycardia WITHOUT absent baseline variability </li></ul></ul><ul><ul><li>Tachycardia </li></ul></ul><ul><li>Baseline FHR variability </li></ul><ul><ul><li>Minimal baseline variability </li></ul></ul><ul><ul><li>Absent baseline variability with no recurrent decelerations </li></ul></ul><ul><ul><li>Marked baseline variability </li></ul></ul><ul><li>Accelerations </li></ul><ul><ul><li>Absence of induced accelerations after fetal stimulation </li></ul></ul>
  31. 49. <ul><li>Periodic or episodic decelerations </li></ul><ul><ul><li>Recurrent variable decelerations accompanied by minimal or moderate baseline variability </li></ul></ul><ul><ul><li>Prolonged deceleration more than 2 minutes but less than 10 minutes </li></ul></ul><ul><ul><li>Recurrent late decelerations with moderate baseline variability </li></ul></ul><ul><ul><li>Variable decelerations with other characteristics such as slow return to baseline, overshoots, or “shoulders” </li></ul></ul>
  32. 53. <ul><li>Absent baseline FHR variability and any of the following: </li></ul><ul><ul><li>Recurrent late decelerations </li></ul></ul><ul><ul><li>Recurrent variable decelerations </li></ul></ul><ul><ul><li>Bradycardia </li></ul></ul><ul><li>Sinusoidal pattern </li></ul>
  33. 55. <ul><li>Early deceleration </li></ul><ul><li>(head compression): </li></ul><ul><li>Late deceleration </li></ul><ul><li>( uteroplacental insufficiency </li></ul><ul><li>Variable deceleration </li></ul><ul><li>(cord compression) </li></ul><ul><li>Combined or mixed patterns </li></ul><ul><li>Decreased beat-to-beat variability </li></ul>
  34. 56. <ul><li>Definition : The onset, maximum fall, and recovery of FHR is a mirror image of the onset, peak, and end of the uterine contraction. </li></ul><ul><li>Significance : This pattern is seen when engagement of the fetal head has occurred. Early decelerations are not thought to be associated with fetal distress. </li></ul><ul><li>Mechanism : The pressure on the fetal head leads to increased intracranial pressure that elicits a vagal response </li></ul>
  35. 57.
  36. 58. <ul><ul><li>Definition : </li></ul></ul><ul><ul><li>---onset </li></ul></ul><ul><ul><li>---maximal </li></ul></ul><ul><ul><li>---decrease </li></ul></ul><ul><ul><li>---recovery is shifted to the right in relation to the contraction . </li></ul></ul>Late Decelerations (Uteroplacental Insufficiency) onset recovery max
  37. 59. <ul><ul><li>Significance : </li></ul></ul><ul><ul><ul><li>The severity is graded by t he magnitude of the decrease and the nadir of the deceleration </li></ul></ul></ul><ul><ul><ul><li>Fetal hypoxia and acidosis are more pronounced with severe decelerations </li></ul></ul></ul><ul><ul><ul><li>Generally associated with low scalp blood PH values and high base deficits, indicating metabolic acidosis from anaerobic netabolism </li></ul></ul></ul>Late deceleration (uteroplacental insufficiency)
  38. 60. <ul><ul><li>Definition: This pattern has a variable time of onset and a variable form and may be nonrepetitive </li></ul></ul>
  39. 61. <ul><ul><li>Significance : </li></ul></ul><ul><ul><li>caused by umbilical cord compression. The severity is graded by their duration. </li></ul></ul>
  40. 62. <ul><li>Partial or complete compression of the cord causes a sudden increase in blood pressure in the central circulation of the fetus. </li></ul><ul><li>The bradycardia is mediated via baroreceptors </li></ul><ul><li>Fetal blood gases indicate respiratory acidosis with a low PH and high CO 2. When cord compression has been prolonged, hypoxia is also present, showing a picture of combined respiratory and metabolic acidosis in fetal blood gases </li></ul>Variable deceletation (cord compression)
  41. 63. <ul><li>A flat baseline can be the result of several conditions: </li></ul><ul><ul><ul><li>Fetal acidosis </li></ul></ul></ul><ul><ul><ul><li>Quiet sleep state </li></ul></ul></ul><ul><ul><ul><li>Maternal sedation with drugs </li></ul></ul></ul>Decreased beat-to beat variability
  42. 65. <ul><li>A normal FHR pattern on the electronic monitor indicates a greater than 95% probability of fetal well-being </li></ul><ul><li>Abnormal patterns may occur, however, in the absence of fetal distress. The false-positive rate (i.e., good Apgar scores and normal fetal-acid-bade status in the presence of abnormal FHR patterns) is as high as 80 % </li></ul><ul><li>Electronic fetal monitoring is a screening rather than a diagnostic technique, because of the high false-positive rate </li></ul>
  43. 66. <ul><li>Clinical circumstance </li></ul><ul><li>Maternal condition </li></ul><ul><li>Stage of labor </li></ul>Clinical Considerations for FHR Interpretation
  44. 67. <ul><li>A change in maternal position can relieves fetal pressure on the cord </li></ul><ul><li>100% oxygen by face mask to the mother </li></ul><ul><li>Oxytocic infusion should be discontinued </li></ul><ul><li>Elevating the presenting part by vaginal examination </li></ul><ul><li>Placing the mother in the trendelenburg position if the pattern is persistent </li></ul><ul><li>Use tocolytic agent to diminish uterine activity </li></ul>What To Do for… Variable Decelerations
  45. 68. <ul><li>Aminioinfusion can decrease both the frequency and severity of variable decelerations </li></ul><ul><li>The benefit of aminioinfusion results in reduced cesarean deliveries for fetal distress and fewer low Apgar scores at birth without apparent maternal or fetal distress </li></ul>What To Do for… Variable Decelerations
  46. 69. <ul><li>The safest intervention to deliver the fetus with cord compression is often low or outlet forceps. </li></ul><ul><li>When progressive acidosis occurs , as determined by serial scalp blood PH determinations, cesarean section should be performed if vaginal delivery is not imminent </li></ul><ul><li>Prolonged deceleration requires </li></ul><ul><li>immediate intervention (FHR </li></ul><ul><li>falls to 60 to 90 bpm for </li></ul><ul><li>more than 2 minutes) </li></ul>What To Do for… Variable Decelerations
  47. 70. <ul><li>Need further evaluation because it may be assosiated with fetal acidosis </li></ul><ul><li>acoustic stimulation can be used to try to induce FHR-accelerations </li></ul><ul><li>A response of greater than 15 bpm lasting at least 15 seconds can ensures the absence of fetal acidosis </li></ul><ul><li>The chance of acidosis occurring in the fetus who fails to respond to such stimulation is about 50% </li></ul>What To Do for… Nonreactive fetal heart rate tracings
  48. 71. <ul><ul><li>Change the maternal position from supine to left or right lateral </li></ul></ul><ul><ul><li>Give oxygen by face mask, this can increase fetal Po 2 by 5 mmHg </li></ul></ul><ul><ul><li>Stop any oxytocic infusion </li></ul></ul><ul><ul><li>Inject intravenously a bolus of tocolytic drug to relieve uterine tetany. </li></ul></ul><ul><ul><li>Monitor maternal blood pressure </li></ul></ul><ul><ul><li>Operative delivery should be considered for fetal distress when fetal acidosis is present or when late decelerations are persistent in early labor and the cervix is insufficiently dilated </li></ul></ul>What To Do for… Late Decelerations
  49. 72. <ul><li>Prolonged periods of tachycardia are usually associated with elevated maternal temperature or an intrauterine infection, which should be ruled out. </li></ul><ul><li>The acid-base status is usually normal </li></ul><ul><li>In general, fetal tachycardia occurs to improve placental circulation when the fetus is stressed. </li></ul><ul><li>Not a reliable change of the fetal distress </li></ul>What To Do for… Fetal Tachycardia
  50. 74. <ul><li>There is an unrealistic expectation that a nonreassuring FHR tracing is predictive of cerebral palsy. </li></ul><ul><li>The positive predictive value of a nonreassuring pattern to predict cerebral palsy is 0.14%. </li></ul>
  51. 75. <ul><li>Out of 1,000 fetuses with a nonreassuring FHR pattern, only one or two will develop cerebral palsy </li></ul><ul><li>The false positive rate of EFM for predicting cerebral palsy is extremely high, at greater than 99%. </li></ul><ul><li>Available data suggest that the use of FHR monitoring does not result in a reduction in cerebral palsy </li></ul>
  52. 76. <ul><li>The interpretation of FHR is more consistent when the tracing is normal </li></ul><ul><li>In retrospective reviews, the foreknowledge of neonatal outcome alters the reviewer’s impressions of the tracing. </li></ul><ul><li>Reinterpretation of the FHR tracing, if neonatal outcome is known, may not be reliable. </li></ul>
  53. 77. MEDICATION EFFECT Narcotics Decrease in variability Decrease in the frequency of accelerations Butorphanol (Stadol) Transient sinusoidal FHR pattern Slight increased mean heart rate Cocaine Decreased long-term variability
  54. 78. MEDICATION EFFECT Corticosteroids Decrease in FHR variability with beta-methasone but not dexamethasone, Abolishes diurnal fetal rhythm. Increased effect at greater than 29 weeks of gestation Magnesium sulfate Decreased short-term variability, Insignificant decrease in FHR.
  55. 79. MEDICATION EFFECT Terbutaline Increase in baseline FHR Increased incidence of fetal tachycardia Zidovudine No difference in the FHR

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