Fetal monitoring Flashcards
What are the definitions of the following
-Tachysystole
-Hypertonus
-Hyperstimulation
- Tachysystole
-More than 5 contractions in 10 minutes during active labour with no fetal HR abnormalities - Hypertonus
-Contraction lasting >2 mins or within 60 seconds of each other without fetal HR abnormalities - Hyperstimulation
-Either tachysystole or hypertonus with FHR abnormalities
Discuss excessive uterine activity
-Causes (5)
-Risks to fetus (2)
-Risk to mother (3)
- Causes
-Prostaglandins for cervical ripening
-Oxytocin for labour
-Placental abruption
-Intrauterine infection
-Rarely seen in spontaneous labour - Risks to fetus
-Fetal hypoxia
-Fetal acidosis - Maternal risks
-AFE
-Uterine rupture
-Risks associated with an emergency caesarian section
Discuss management for excessive uterine activity
-Steps to take with hyperstimulation (5)
-Indications for tocolysis
-Contra-indications for tocolysis
- Steps to take with hyperstimulation
-Continue fetal monitoring
-Stop / decrease oxytocin infusion
-Consider tocolytics
-Assess requirement for urgent delivery
-Provide 1:1 care until normalised - Indications for tocolysis
-Excessive uterine activity resulting in hyperstimulation
-If no evidence of fetal compromise tocolysis is not indicated - Contra-indications for tocolysis
-Placental abruption
-Maternal cardia disease
Discuss terbutaline as a tocolytic
-Class of drug
-Mode of action
-Dose
-Side effects (5)
-Contra-indications (3)
-Literature findings (2)
- Class of drug - selective B2 adrenergic receptor agonist
- MOA - relaxation of uterine smooth muscle
- Dose 250mcg S/C stat. IV 50mcg in bolus
- Side effects
-Maternal tachycardia, palpitations, arrythmia
-Headache, anxiety , tremor
-Nausea and vomiting - Contraindications
-Sympathomimetic amine sensitivity
-Placental abruption
-Relative contra-indications - maternal cardiac disease, Hypotension, hyperthyroidism - Literature findings
-Doesn’t increase bleeding risk regarding atony
-Moderate evidence to suggest best tocolytic in terms of fetal HR abnormalities
Discuss salbutamol as a tocolytic
-Class of drug
-Mechanism of action
-Dose
-Side effects (6)
-Contra-indication (3)
- Class of drug: Selective B2 adrenergic receptor agonist
- MOA: Smooth muscle relaxation
- Dose
IV 25-50mcg boluses to max of 250mcg - Side effects
-Maternal tachycardia, palpitations, arrythmias
-Nausea and vomiting
-Tremor, anxiety, headache - Contra-indications
-Cardiac disease
-Hypertension
-Hyperthyroid
Discuss GTN as a tocolytic
-Mechanism of action
-Dose
-Side effects (3)
-Contra-indications (4)
- MOA: Relaxes vascular smooth muscle and also uterine smooth muscle
- Dose 400mcg per spray. Can give 2 5 mins apart
- Side effects
-Headache
-Hypotension
-Reflex tachycardia or bradycardia - Contra-indications
-Acute circulatory failure
-Cardiac disease
-Hypotension
-Severe anaemia
Discuss fetal bradycardia
-Definition (2)
-What is the mechanism by which fetal bradycardia occurs
- Definition
-FHR ,110
-FHR < 15 beats below baseline for >5mins - Mechanism
-Fetal chemoreceptors identify reduced oxygen levels and this results in reflex vagal stimulation to reduce heart rate and cardiac output to reduce myocardial oxygen requirement
Discuss causes of acute fetal bradycardia
-Hypoxic causes attributed to the mother (4)
-Hypoxic causes attributed to the utero-placental unit (3)
-Hypoxic causes attributed to the fetus (3)
- Hypoxic causes - maternal
-Maternal hypoxemia - seizure, hypoventilation, resp disease
-Maternal hypotension - positioning, epidural, sepsis
-Reduced oxygen carrying capacity - anaemia, smoking
-Chronic medical conditions - diabetes, HTN - Utero-placental unit causes
-Excessive uterine activity
-Reduced surface area of placenta for gas exchange - abruption, IUGR
-Uterine rupture - Fetal causes
-Cord compression - Cord prolapse, true knot in cord, oligohydramnios.
-Decreased oxygen carrying capacity- fetal anaemia
-Rapid decent of fetal head through pelvis
What are the causes of a fetal baseline bradycardia
-Maternal (4)
-Fetal (2)
- Maternal
-Recording maternal HR
-Opiates
-Beta blockers
-MgSO4 - Fetal
-Post dates with increased PNS drive
-Fetal heart conduction defect - Fetal heart block
Discuss fetal blood sampling
-Normal lactate and pH
-Pre-acidotic lactate range and pH
-Acidotic range and pH
- Normal range
-Lactate <4.0
-pH >7.25 - Pre-acidotic
-Lactate 4.1 - 4.7
-pH 7.21- 7.24 - Acidotic range
-Lactate >4.7
-pH <7.21
What are the contra-indications to FBS (5)
- < 34 weeks
- Non-vertex presentation
- Possible fetal bleeding disorder
- Maternal infection - HIV/ Hep B, HSV (GBS doesn’t preclude FBS)
- Evidence of serious sustained fetal compromise
Discuss action for the following FBS findings
-Lactate <4.0 (pH > = 7.25)
-Lactate 4.1 - 4.7 (pH 7.21 - 7.24)
-Lactate >4.7 (pH <7.20)
- Lactate <4.0 - Normal range
-If CTG returns to normal no need to repeat lactate
-If CTG abnormalities persist repeat in an hr
-If CTG abnormalities worsen repeat in less than an hour - Lactate 4.1-4.7 - Pre-acidotic
-Recheck in 30 mins to see trend
-Deliver earlier if significant deterioration - Lactate >4.7 - Acidotic
-Stop oxytocin if in process
-Expedite delivery - CS or Instrumental
What are the advantages and disadvantages to FBS
-Advantages (2)
-Disadvantages (1)
- Advantages
Can assist in the interpretation of equivocal CTG
Can reduce CS rates
-CS risk if CTG and no FBS - OR - 2
-CS risk if CTG and FBS OR 1.55
Discuss cord blood sampling
-When should it be taken (4)
-Apgar <4 and 1 min
-Apgar <7 at 5 mins
-Fetal scalp sampling during labour
-Operative delivery undertaken for fetal compromise
What do the cord bloods represent
-Venous gas
-Arterial gas
-Abnormal results (6)
-How are they used (2)
- Venous gas
- maternal acid-base status and placental function
-Expect to be less acidotic - normal >7.32 - Arterial gas
-fetal status
-Expect to be more acidotic as more CO2 from fetal metabolism - normal >7.24 - Abnormal results
-Lactate >7.5
-Base excess <-12
-pH <7.0
-Big difference between arterial (acidotic) and venous (less acidotic) - suggests cord compression of umbi vein
-Both bad - likely placental
-Both the same then probably both venous - How are cord gases used
-Can predict poor neurological outcomes if baby also unwell
-Can guide when to cool babies - pH <7 and Base excess <-12
-Base excess from -12 -> -16 is a significant predictor of neonatal neurological morbidity. 10% chance of severe neurological impairment