obstetrics facts Flashcards
WHO class 5 heart issues in obstetrics
Pulmonary arterial hypertension (any cause)
Severe systemic LV dysfunction (NYHA III/IV, LVEF <30%)
Previous peripartum cardiomyopathy and residual LV dysfunction
Aortic root dilation >45mm (Marfan) or >50mm (bicuspid valve)
Severe MS, AS or coarctation
List 2 reasons why asthma can lead to improvement in asthma?
Progesterone effects on bronchial smooth muscle
Increased production of corticosteroid
List 4 reasons why there is deterioration in some patients with asthma during pregnancy
Reduced sensitivity to β-agonists
Increased prostaglandin levels causing bronchoconstriction
Reduced cortisol sensitivity (as progesterone binds the receptor)
Reluctance to take usual medications
3 complications asthmatic parturients at greater risk of?
Asthmatic parturients are more likely to have complications such as pre-term delivery, low birth weight and pre-eclampsia
Name one key difference in management of an acute attack for pregnant vs non-pregnant patients
Management is the same as for non-pregnanct patients
One difference is a patient should be deemed to be ‘tiring’ at a PaCO2 of 4.0kPa, rather than a normal PaCO2, owing to the lower levels during pregnancy
Follow-up frequency depends on WHO class- class 1, 2 and 3/4/5?
Follow-up frequency depends on WHO class e.g. class I (1-2x in pregnancy), class II (1x per trimester) or class III/IV (1-2x per month)
name some changes to ECG due to pregancy alone
LVH
15-20’ left axis deviation
ST-segment and T-wave changes
Lead III: Q-wave and inverted T-wave
Lead AvF: attenuated Q wave
V1-3: inverted T-wave
Atrial or ventricular ectopics
Sinus tachycardia
goals in management of cardiac pregnant patients
Minimise cardiovascular stress by minimising the work of labour and delivery
Monitor and maintain fluid balance
Avoid aortocaval compression
Provide aspiration prophylaxis
Implement invasive monitoring
Assisted vaginal delivery ± early, incremental, epidural analgesia benefits?
This mode of delivery is advantageous over un-assisted vaginal delivery because there are fewer surges in cardiac output associated with pushing
It is also advantageous over LSCS due to:
Less blood loss
Reduced stress response
Reduced incidence of post-partum pulmonary complications, sepsis and VTE
Early, incremental, epidural analgesia has several advantages?
Early, incremental, epidural analgesia has several advantages:
Limits increased cardiac output from pain due to analgesic effect
Reduces both preload and afterload
Limits sympathetic block by careful titration of the level of epidural block required
May be topped up for anaesthesia if required
LCSC reserved for what group of cardiac patients?
Typically reserved for either obstetric indications or specific, high-risk maternal conditions:
Marfan syndrome with aortic root dilation >45mm
Acute or chronic aortic dissection
Intractable cardiac failure
Severe pulmonary artery hypertension
Severe aortic stenosis
The choice of anaesthetic for a LSCS should take into account the underlying cardiac disease and severity, wishes of the mother and anaesthetist’s preferences
Uterotonics
Uterotonics in cardiac patients
Oxytocin when given as a rapid bolus can cause marked tachycardia, reduced SVR and reduced PVR
Therefore boluses are avoided and an infusion alone may be used
Ergometrine is avoided as it causes increased SVR, PVR and coronary vascular resistance
Carboprost should be avoided due to profound vasodilation, especially when SVR maintenance is important e.g. aortic stenosis
How to treat vasodilatation associated with regional technique in patients with cardiac disease
Vasodilation is a feature and should be controlled with titratable vasopressors
Phenylephrine is preferred in stenotic valve lesions to maintain SVR
Ephedrine is preferred in regurgitant valvular lesions due to its positive chronotropic effect
disadvantages of a GA section in cardiac patients
Those inherent to GA, inc. aspiration, failed I&V, anaesthetic effects on foetus
↑ blood loss compared to regional anaesthesia
Cardiac instability due to pressor effects of intubation
Effect of GA drugs, which are typically cardiac depressants and/or vasodilatory
benefits of a GA in cardiac obstetric patients
Advantages
Reduced maternal anxiety:
↓ catecholamine release and less cardiac work
Stable parameters if ‘cardiac anaesthetic’ provided
Suitable in the anticoagulated patient
Monitoring under GA for cardiac obstetrics patients
Standard AAGBI monitoring
Arterial line
Central line may be required, although caution is required with CVP monitoring in the obstetric patient as:
Anatomical variation of the SVC may mean CVC line tip is not where it should be
Irritation by the CVC line may precipitate arrhythmias
Underlying cardiac disease means CVP may not reflect LVEDV
CVP may be a less reliable guide to volume status, especially in PET
TOE may be useful
Conduct of GA cardiac anaesthesia
One should aim to avoid tachycardia and large swings in blood pressure
At induction, obtund the hypertensive response to intubation (e.g. alfentanil 25μg/kg, remifentanil 0.5μg/kg) and titrate induction agent carefully
Maintenance is typically with volatile anaesthetic, although addition of remifentanil is useful to:
Reduce volatile requirement and therefore risk of atonic PPH
Reduce chance of hypertension on extubation if continued during emergency
Good analgesia is paramount because pain and tachycardia increase cardiac work; epidural/neuraxial opioids and use of other regional techniques e.g. TAP blocks
Post-partum care of cardiac obstetric patient?
Planned admission to HDU/ITU may be required for 24-48hrs post-delivery
Mortality due to maternal cardiac disease tends to be post-partum, due to:
Reduced frequency of monitoring compared to ante-natal period
Large fluid shifts in the post-partum period including 500ml autotransfusion at the time of delivery → acute decompensation
Sub-optimal or early withdrawal of analgesia leading to catecholamine surges from pain → worsening cardiac function or arrhythmias
There is an increased incidence of congenital abnormalities with anti-epileptic drugs
Valproate is the most teratogenic of the lot
Patients should have their medication altered by a Neurologist; the lowest effective dose of a single agent should be used
1/3rd of patients experience… in epilepsy pregnancy…
3 things
1/3rd of patients experience worsening seizure frequency, owing to:
Hormonal changes
Altered pharmacokinetics of anti-epileptic drugs
Poor concordance with anti-epileptics
1/3rd of patients experience no change in seizure frequency
1/3rd of patients experience an improvement in seizure frequency
5 issues with drugs which are convulsant in epileptics
One should avoid pethidine, whose active metabolite norpethidine is pro-convulsant; other peripartum analgesics are mostly fair game
Tramadol, a technically viable although seldom-used post-operative analgesic, lowers the seizure threshold - especially in combination with SSRIs or TCAs
Tranexamic acid can induces seizures although this is unlikely in the 1-2g dosing regimen one might use in Obstetrics
If seizures occur they should be treated in the standard fashion (see notes from the ICM section on status epilepticus)
One should be mindful that seizures can be a manifestation of eclampsia, which should be excluded or treated accordingly
