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
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
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
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
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
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
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.
