Obs Flashcards
List features of the foetal heart rate that are used to define and interpret CTG traces
- Baseline (normal= 110-160 beats/min abnormal <100 or >180)
- Baseline variability (normal= 5-25beats/min, abnormal <5 or >25 for >50mins)
- Decelerations (late decels, brady and prolonged)
Each feature can be described as reassuring, non-reassuring or abnormal
How can a CTG trace be categorised?
- Normal (if all features reassuring)
- Suspicious (if one feature non reassuring)
- Pathological (one abnormal feature or two non reassuring features)
- Need for urgent intervention (acute bradycardia or prolonged deceleration)
Give the normal, borderline and abnormal values for pH and lactate in a foetal blood sample
pH:
Normal >7.25
Borderline 7.2-7.25
Abnormal <7.2
Lactate
Normal <4.1
Borderline 4.2-4.8
Abnormal >4.9
Describe the categories of caesarean section
Cat 1: Immediate threat to life of woman or foetus, time from decision to delivery should be <30mins
Cat 2: Maternal or foetal compromise which is not immediately life threatening, time from decision to delivery should be <75mins
Cat 3: No maternal or foetal compromise but requires early delivery
Cat 4: Delivery timed to suit women or staff
List indications for elective caesarean section
- Maternal request
- Malrpresentation, failed ECV
- Multiple pregnancy and first twin not cephalic
- Placenta praevia
- Placenta accreta
- Previous C-S
- Previous traumatic delivery
- Transmissible diseases e.g. HIV, genital HSV
- Cephalopelvic disproportion
- Maternal conditions e.g. diabetes, cardiovascular disease
Methods of monitoring for foetal wellbeing
CTG
Foetal scalp monitoring
Foetal pulse oximetry
Foetal blood sampling
Foetal ECG
Transabdominal ultrasound
Which sensory modalities can be assessed to check the adequacy of neuraxial block prior to c-section, and which height of block should be achieved for each?
- Light touch to T5 bilaterally
- Temperature e.g. cold to T4 bilaterally
What degree of motor block is consistent with adequate neuraxial block for c-section?
Inability to straight leg raise against gravity bilaterally
Give reliable signs that indicate sympathetic block associated with neuraxial anaesthesia
Warm and dry feet bilaterally
State three ways that initially inadequate spinal block can be improved to allow caesarean section to proceed
- Positioning - flex hips to flatten lumbar lordosis, cautious head down tilt, lateral tilt if block is not equal to both sides
- Epidural/ top-up
- Repeat spinal with reduced dose (if some block present), patient positioning to reduce risk of high spinal
What are the risk factors for failure of neuraxial anaesthesia
Surgical
* Greater operative urgency
* Longer surgery
Patient
* High BMI
* First c-section
Anaesthetic
* No intrathecal opioid used
What are the risk factors for post-operative pain when epidural is used for C-section
- High top-up volume required to achieve adequate block
- Adrenaline not used
- Higher number of clinican administered boluses during labour
Aside from improving block and providing a GA, what can you do for management of pain during C-section?
- Nitrous oxide
- Fast acting opioids e.g. alfentanil 250-500mcg boluses
- Ketamine 10mg boluses
Define late intrauterine fetal death
Fetal death in utero after 24 completed weeks of pregnancy
List pre-existing maternal conditions that are associated with inreased risk of IU-fetal death
- Diabetes
- SLE
- Advanced maternal age
- Obesity
- Maternal drug use
- Maternal thrombophilias
- RhD -ve
List obstetric causes of IU-fetal death
- Pre-eclampsia
- PROM
- Placental abruption
- Cord prolapse
- Ascending infection
- Uterine rupture
- Obstetric cholestasis
State ways in which the approach to pain relief may differ between labour with IU-fetal death and live birth
- Maternal pain may be greater due to psychological distress
- Choice to use analgesia may be affected by holistic situation
- No concerns over placental transfer of analgesics - longer acting and higher opiate doses can be used if needed
- Opiates with fewer side effects e.g. morphine can be used instead of pethidine
- Causes of consequences of IUFD may induce coagulopathy, contraindicating neuraxial and intramuscular analgesia
Give abnormal haematological results which may contraindicate epidural analgesia, and why these might be seen in IU-fetal death
- Raised WCC - maternal sepsis contributing to IUFD, or as a consequence of IUFD
- Low platelets - severe pre-eclampsia or HELLP
- Derranged coagulation - DIC from pre-eclampsia/HELLP/thrombophilia/abruption/uterine rupture or because of IUFD itself
Give the features of a post-dural puncture headache
- Fronto-occipital
- Develops within five days of puncture
- Worse on standing, improves on lying
- Neck stiffness
- Tinnitus
- Photophobia
- Sound intolerance
- Cranial nerve palsies e.g. II, III, IV, VI. VIII
Give risk factors for accidental dural puncture
- Extremes of BMI
- Increased depth to epidural space
- Operator inexperience
- Inability of patient to remain still (e.g. advanced labour)
What are the differential diagnoses of post-partum headache?
- Meningitis
- Sinusitis
- Migraine
- Cerebral vein thrombosis
- Dehydration
- Lactation headache
What conservative management do you advice for post dural puncture headache?
- Simple analgesia e.g. paracetamol, NSAIDs
- Good hydration
- Caffeine
- Encourage mobilisation, if unable give antiembolism stockings
- Avoid straining - laxatives
- Antiemetics if needed
What are the risks of epidural blood patch?
- Failure
- Bruising
- Temporary back pain/stiffness
- Further accidental dural puncture
- Nerve damage
- Infection
- Spinal canal haematoma
What are the causes of mitral stenosis?
- Infective endocarditis
- Degenerative calcification
- Rheumatic fever
What are the physiological cardiovascular changes in pregnancy and how can these exacerbate pathophysiology of mitral stenosis
- Increased circulating volume - fixed left atrial output unable to cope, pulmonary oedema, increased left atrial stretch, risks atrial fibrillation, further reduced left atrial emptying
- Increased heart rate - shorter diastole and reduced time for flow across stenosed valve, reduced left ventricular filling, reduced cardiac output
- Reduced SVR - reduction in coronary artery perfusion, risk of ischaemia
- Increased oxygen consumption (due to fetus + maternal metabolism) requires increased cardiac output which cannot be facilitated with severely stenosed mitral valve, leading to decompensated heart failure
List the pharmacological interventions that might be required to manage mitral stenosis in pregnancy
- Beta blocker for heart rate control
- Anticoagulation if at risk of AF
- Diuretics if congestive symptoms
What are the haemodynamic goals for mitral stenosis and how can they be achieved during management of labour
- Avoid tachycardia - early pain management with epidural, avoid oxytocin boluses, prompt management of hypovolaemia
- Maintain afterload - slowlu incremental epidural block, alpha-agonist infusion e.g. phenylephrine
- Avoid arrhythmia - continue prescribed medications e.g. beta agonists, avoid increasing load of left atrium with excessive fluid administration, electrical cardioversion if haemodynamic instability following acute onset AF
- Avoid rises in pulmonary arterial pressure - assisted delivery to avoid valsalva from pushing, avoid nitrous oxide, avoid ergometrine
Which events after delivery can predispose to pulmonary oedema in a patient with mitral stenosis?
- Autotransfusion due to contraction of uterus
- Loss of aortocaval compression
A 28-year old woman presents for acute appendicectomy - she is 22 weeks pregnant. List the risks to fetus during GA and why they may occur.
- Hypoxia - maternal hypoxia in event of difficult airway management
- Fetal hypercarbia and myocardial depression - maternal hypercarbia in event of difficult airway management
- Fetal artery vasoconstriction - maternal hypocarbia due to hyperventilation or hypercarbia in event of difficult maternal airway
- Fetal hypoperfusion - aortocaval compression, maternal hypotension during induction
- Adverse neurological outcomes - anaesthetic-induced neuronal apoptosis in developing brain
- Miscarriage - more likely secondary to disease process necessating surgery
Give pre and intraoperative steps to maximise fetal safety if a GA is required to a mother at 27 weeks
- Consider risk of premature labour - involvement of NICU and obstetricians
- Consider fetal monitoring
- Consider tocolysis
- Consider steroids for fetal lung maturation
- Avoid NSAIDs (risks premature closure of ductus arteriosus)
Which changes in maternal physiogy in late pregnancy increase the risk of maternal and therefore fetal hypoxia at induction of general anaesthesia
- Reduction in functional residual capacity - reduced apnoeic time before desaturation
- Increased oxygen consumption due to increased metabolic demand of pregnant woman and increased oxygen demand due to fetoplacental uit
Give considerations to maximise the safety of laparoscopic surgery in a pregnant patient
- Control maternal end-tidal carbon dioxide
- Use open technique to enter abdomen
- Low pneumoperitoneum pressures < 12 mmHg
- Limit trendelenburg positioning, achieve desired position slowly
- Fetal monitoring if feasible
Which analgesics are contraindicated when breast feeding
- Codeine phosphate (respiratory depression baby)
- Tramadol (respiratory depression baby)
- Analgesic dose aspirin (Reye’s syndrome)
What is required to make an advance decision valid in order to refuse life-saving treatment?
- Patient over 18 years old
- Patient has capacity at time of writing decision
- Patient has lost capacity at time of application of advance decision
- Written document
- Signed by patient or on patient’s direction if unable to sign
- Witnessed with signature
- Specifies the treatments the patient refuses to have
- Acknoweledges risk of death as a consequence of refusal
- Has not been later withdrawn in writing or verbally
What pharmacological approaches can be used to minimise the risk of consequences of haemorrhage in an elective c-section with placenta praevia and fibroid uterus
- Pre-op optimisation of haemoglobin with iron
- Consider need for erythropoetin
- Uterotonics e.g. oxytocin infusion, long acting oxytocin (carbetocin), escalation plan for uterotonics
- Stop any drugs with an adverse effect on bleeding e.g aspirin, low molecular weight heparin
- Use tranexamic acid
Jehova’s witness patient, refusing blood products. Elective CS, fibroids, placenta praevia.
State risks to be discussed with this patient before they make their advanced decision
- Potential for haemorrhage is increased due to fibroids and placenta praevia
- Risk of death if blood not given in event of massive haemorrhage - no true blood alternatives
- Risk of major morbidity from massive haemorrhage including prolonged ICU stay, prolonged ventilation, poor wound healing, infection, hysterectomy, difficulties caring for newborn
Give advantages of intraoperative cell salvage during c-section
- Avoids risks of allogenic transfusion e.g. blood administration errors, transfusion reactions, viral/bacterial/prion tranmission
- Blood reinfused at room temperature, reduce risk of transfusion associated hypothermia
- Useful in patients with atypical antibodies where cross match is difficult and turnaround is longer
- Salvaged blood has normal 2,3-DPG levels so normal oxygen carrying behaviour
- Often acceptable to Jehova’s witnesses
- Consumables only cost slightly more than one unit of donated blood
Give the problems associated with intraoperative cell salvage during c-section
- Leucocyte depletion filter slows infusion rate and can result in release of bradykinin causing hypotension
- Does not reinfuse platelets or coagulation products
- Risk of air embolism and amniotic fluid embolism
- Red cell lysis due to “skimming” reduces the availability of whole cells for reinfusion
- Staff training necessary
- Risk of bacterial contamination
- Risk of electrolyte imbalance
- Risk of circulatory overload
State the definition of pre-eclampsia
- New onset hypertension (>140/90 two readings 4 hours apart) after 20 weeks gestation
- Accompanied by evidence of proteinuria/ maternal organ dysfunction (neuro, liver, kidney, haem)/uteroplacental dysfunction
Neuro e.g. headache, central scotoma, altered mental status, seizures. Liver- transaminitis. Kidneys- creatinine above 90, haem - platelets < 150, DIC, haemolysis)
List the symptoms of pre-eclampsia that should be reported by women if experienced
- Severe headache
- Visual changes e.g. blurring, flashing
- Severe pain just below the ribs
- Vomiting
- Sudden swelling of hands, face or feet
Define eclampsia
Seizures on a background of pre-eclampsia
Give risk factors for the development of pre-eclampsia
- Hypertensive in previous pregnancy
- CKD
- Autoimmune disease
- Pregestational diabetes
- Primip
- > 40 yrs
- BMI over 35kg/m2
Which drugs may be used intravenously to control raised blood pressure in pre-eclampsia
- Labetalol (10-20mg initially)
- Hydralazine (5-10mg initially)
When is magnesium sulphate indicated for pre-eclampsia
- Severe pre-eclampsia in critical care setting when delivery planned within 24hrs
- For seizures and prevention of further seizures
What are the features of severe pre-eclampsia?
- SBP ≥160 mmHg or DBP ≥110 mmHg
- Thrombocytopaenia (platelet count ≤100x10^9/L)
- Impaired liver function (ALT/AST> twice the upper limit of normal, severe persistent right upper quadrant or epigastric pain not accounted for by alternative diagnoses)
- AKI (doubling of creatinine)
- Pulmonary oedema
- New onset headache, unresponsive to medication and not accounted for by alternative diagnoses
- Visual disturbance