CTG for the anaesthetist

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  • 1. CTG = cardiotocography CTG for the anaesthetist 6/13/20141 amr moustafa kamel. CTG for the anaesthetist
  • 2. What is cardiotocography?  A cardiotocograph is a device used in pregnancy to monitor both the fetal heart as well as the contractions of the uterus. It is usually only used in the 3rd trimester and mainly during labor. It’s purpose is to monitor fetal well-being & allow early detection of fetal distress.An abnormal CTG indicates the need for more invasive investigations (e.g. fetal blood sample) & ultimately may lead to emergency caesarian section. 6/13/20142 amr moustafa kamel. CTG for the anaesthetist
  • 3. It involves the placement of 2 transducers on the abdomen of a pregnant woman. One transducer records the fetal heart rate using ultrasound. The other transducer monitors the contractions of the uterus. It does this by measuring the tension of the maternal abdominal wall. This provides an indirect indication of intrauterine pressure 6/13/20143 amr moustafa kamel. CTG for the anaesthetist
  • 4. Indications of CTG monitoring The UK National Institute of Health and Clinical Excellence (NICE) make recommendations for continuous CTG monitoring which include: 1. Meconium staining of liquor 2. Maternal pyrexia – defined as 38.0 °C or 37.5 °C on two occasions two hours apart 3.The use of oxytocin for labour augmentation 4. Fresh bleeding developing in labour 5.At the woman’s request 6.Abnormal FHR detected during intermittent auscultation: FHR <110 beats per minute (bpm), FHR >160 bpm,Any decelerations after a contraction 8.Women receiving regional anesthesia/analgesia. Continuous electronic fetal monitoring is recommended for at least 30 minutes during establishment of regional analgesia and after administration of a further bolus of local anesthetic agent. In most UK centers, continuous CTG monitoring is performed after the insertion of a labour epidural. 6/13/20144 amr moustafa kamel. CTG for the anaesthetist
  • 5. INTERPRETATION OF THE CTG 6/13/20145 amr moustafa kamel. CTG for the anaesthetist
  • 6. Each big square equals to 1 min on the X axis Each big square is 20 fetal heart beats Uterine contractions 6/13/20146 amr moustafa kamel. CTG for the anaesthetist
  • 7. Uterine contractions 6/13/20147 amr moustafa kamel. CTG for the anaesthetist
  • 8. Baseline fetal heart rate The baseline fetal heart rate should be between 110 and 160 Bpm. It’s done by looking at the average line of the fetal heart rate over 10 minutes (10 big squares) ignoring accelerations & decelerations 6/13/20148 amr moustafa kamel. CTG for the anaesthetist
  • 9. Baseline Fetal bradycardia (<110 Bpm) 6/13/20149 amr moustafa kamel. CTG for the anaesthetist
  • 10. Causes of baseline fetal bradycardia Many cases of fetal baseline bradycardia have no identifiable cause but may occur as a result of:  Cord compression and acute fetal hypoxia  Post-maturity (> 40 weeks gestation)  Congenital heart abnormality  Cord prolapse  Epidural & SpinalAnesthesia 6/13/201410 amr moustafa kamel. CTG for the anaesthetist
  • 11. Baseline fetal tachycardia (>160 Bpm) 6/13/201411 amr moustafa kamel. CTG for the anaesthetist
  • 12. causes of baseline fetal tachycardia Fetal tachycardia is associated with:  Excessive fetal movement or uterine stimulation  Maternal stress or anxiety  Maternal pyrexia (especially due to chorioamnionitis)  Fetal infection  Chronic hypoxia  Prematurity (<32 weeks gestation)  Maternal hyperthyroidism or anemia 6/13/201412 amr moustafa kamel. CTG for the anaesthetist
  • 13. Beat to beat variability the variation of fetal heart rate from one beat to another is called beat to beatVariability occurs as a result of the interaction between the nervous system (sympathetic and parasympathetic), chemoreceptors, barorecptors & cardiac responsiveness.Therefore it is a good indicator of how healthy the fetus is at that moment in time. Normal variability is between 5-25 bpm.Variability can be measured by analyzing a one-minute portion of the CTG trace and assessing the difference between the highest and lowest rates during that period. 6/13/201413 amr moustafa kamel. CTG for the anaesthetist
  • 14.  Baseline FHR variability is determined in a 10-minute window, excluding accelerations and decelerations. Baseline FHR variability is defined as fluctuations in the baseline FHR that are irregular in amplitude and frequency.The fluctuations are visually quantitated as the amplitude of the peak-to-trough in bpm. Using this definition, the baseline FHR variability is categorized by the quantitated amplitude as:  Absent- undetectable  Minimal- greater than undetectable, but less than or equal to 5 bpm  Moderate- 6-25 bpm  Marked- greater than 25 bpm 6/13/201414 amr moustafa kamel. CTG for the anaesthetist
  • 15. 6/13/201415 amr moustafa kamel. CTG for the anaesthetist
  • 16. 6/13/201416 amr moustafa kamel. CTG for the anaesthetist
  • 17. Causes of reduced variability  Fetus sleeping - this should last no longer than 40 minutes – most common cause  Fetal acidosis (due to hypoxia) – more likely if late decelerations also present  Fetal tachycardia  Drugs – opiates, benzodiazepine's,methyldopa, magnesium sulphate  Prematurity – variability is reduced at earlier gestation (<28 weeks)  Congenital heart abnormalities 6/13/201417 amr moustafa kamel. CTG for the anaesthetist
  • 18. Accelerations 6/13/2014amr moustafa kamel. CTG for the anaesthetist18 Accelerations are a fetal response to stimulation and are demonstrated by transient increases in the fetal heart rate of 15 bpm or more above the baseline rate, lasting 15 seconds or more, at the baseline. Accelerations commonly occur as a result of fetal movement, where that movement brings about an increase in sympathetic stimulation from the cardio-regulatory centre (CRC).This increase in the fetal heart rate and so cardiac output, increases the take up of oxygen from the placenta, required to meet the increased oxygen demands of the moving fetus.
  • 19. Reactivity is defined as the presence of two or more accelerations within a twenty minute period. the absence of accelerations with an otherwise normal CTG is of uncertain significance 6/13/2014amr moustafa kamel. CTG for the anaesthetist19
  • 20. Decelerations 6/13/2014amr moustafa kamel. CTG for the anaesthetist20 Decelerations are an abrupt decrease in baseline heart rate of >15 bpm for >15 seconds usually associated with uterine contractions. There are 4 different types of decelerations, each with varying significance. • Early • Late •Variable • Prolonged
  • 21. Early decelerations start when uterine contraction begins & recover when uterine contraction stops (mirror image). This is due to increased fetal intracranial pressure causing increased vagal tone. This type of deceleration is considered to be physiological & not pathological. more importantly they do reflect a well oxygenated fetus. 6/13/2014amr moustafa kamel. CTG for the anaesthetist21
  • 22. 6/13/2014amr moustafa kamel. CTG for the anaesthetist22 Late decelerations begin at the peak of uterine contraction & recover after the contraction ends.This type of deceleration indicates there is insufficient blood flow through the uterus & placenta As a result blood flow to the fetus is significantly reduced causing fetal hypoxia & acidosis. Causes include: • Hypoxia • Placental abruption • Cord compression / prolapse • Excessive uterine activity • Maternal hypotension / hypovolemia
  • 23. They start after the start of the contraction and the bottom of the deceleration is usually more than 20 seconds after the peak of the contraction. Importantly, they return to the baseline after the contraction has finished. this will include decelerations of less than 15bpm. 6/13/2014amr moustafa kamel. CTG for the anaesthetist23
  • 24. The presence of late decelerations is taken seriously, fetal resuscitation & fetal blood sampling for pH is indicated. If fetal blood pH is acidotic (< 7.2) it indicates significant fetal hypoxia & the need for emergency C-section 6/13/2014amr moustafa kamel. CTG for the anaesthetist24
  • 25. Variable decelerations describe FHR decelerations that are both variable in timing and size.They may be accompanied by increased variability of the FHR.They are caused by compression of the umbilical cord and may reflect fetal hypoxia. 6/13/2014amr moustafa kamel. CTG for the anaesthetist25
  • 26. 6/13/2014amr moustafa kamel. CTG for the anaesthetist26 variable decelerations often occur with contractions. However, it is important to recognize that they are a cord compression event, not necessarily a contraction event. typically they vary in depth from one another, vary in duration and vary in timing relative to the uterine activity; hence the name. they have a rapid descent and a rapid recovery. The presence of persistent variable decelerations indicates the need for close monitoring.
  • 27. Prolonged decelerations are decelerations of more than 30 Bpm amplitude and lasts for more than 2 minutes.They are caused by hypoxia but more typically reflect the fetal environment. 6/13/2014amr moustafa kamel. CTG for the anaesthetist27
  • 28. 6/13/2014amr moustafa kamel. CTG for the anaesthetist28 Common causes of a prolonged deceleration include prolonged contractions, uterine hyper stimulation, supine hypotension, post-epidural insertion, placental abruption or a ruptured uterus. Action must be taken quickly – e.g. Fetal blood sampling /fetal resuscitation techniques/ emergency C-section.
  • 29. Sinusoidal Pattern:This type of pattern is rare, however if present it is very serious. It indicates loss of autonomic nervous system control. It is associated with high rates of fetal morbidity & mortality. Immediate C-section is indicated for this kind of pattern. Outcome is usually poor 6/13/2014amr moustafa kamel. CTG for the anaesthetist29
  • 30. 6/13/2014amr moustafa kamel. CTG for the anaesthetist30
  • 31. intrauterine fetal resuscitation 6/13/2014amr moustafa kamel. CTG for the anaesthetist31 A number of maneuvers can be performed to improve fetal oxygenation before delivery. These may be performed with continuous CTG monitoring and if successful may reduce the urgency to deliver allowing time to provide neuraxial anesthesia. 1. Syntocinon off 2. Position full left lateral 3. Oxygen high flow 4. I.V. – infusion of crystalloid fluid 5. Treat Low blood pressure if present give i.v. vasopressor 6. Tocolysis - terbutaline 250 mcg sc (a β2-agonist) or GTN (2 x 400mcg puffs sublingual). Tocolysis is contraindicated in cases of ante partum hemorrhage.