PREGNANCY INDUCED HYPERTENSION & ECLAMPSIA Wesley Edwards Wishaw General Hospital

Scope Definitions Aetiology Pathophysiology Management Anaesthetic Implications

Definitions Hypertension – sustained systolic BP > 140mmHg or diastolic BP> 90mmHg Chronic Hypertension – hypertension which predates pregnancy or is diagnosed before 20wks gestation PIH – hypertension diagnosed after 20 weeks gestation in a patient without a history of chronic hypertension Pre-eclampsia – PIH in association with renal involvement causing proteinuria (>300mg/24h or 2+ on dipstick

Definitions Severe Pre-eclampsia – pre-eclampsia in association with any of: Sustained BP > 160/110 Proteinuria >5g/24hrs or 3+ on dipstick Urine output <400ml/24hrs Pulmonary oedema or evidence of pulmonary compromise Epigastric or RUQ pain Hepatic rupture Platelet count <100 x 10 9 /L Evidence of cerebral complications

Definitions Eclampsia – convulsions occurring in pregnancy or peurperium in the absence of other causes Many view as continuous spectrum with mild PIH at one end and eclampsia at the other PIH affects 6-8 percent of all pregnancies One of the leading causes of maternal morbidity and mortality, responsible for approx 15% of maternal deaths Perinatal mortality ranging from 8-37%

Aetiology Unknown Theories Toxaemia Immunological and genetic factors Reduced levels of nitric oxide Imbalance of thromboxane and prostacyclin – favours vasoconstriction

Pathophysiology - Cardiorespiratory Hypertension Reduced circulating volume Increased total body water Increased sensitivity to catecholamine and exogenous vasopressors Variable central haemodynamic states Increased capillary permeability – pulmonary oedema and ARDS

Pathophysiology - Haemotological Thrombocytopenia – up to 18% in pre-eclampsia, up to 30% in eclamptic women Increased platelet consumption – thought due to underlying damage to endothelium DIC may result May develop coagulopathy

Pathophysiology - Renal Reduced GFR Glomerulopathy – increased permeability to large molecules resulting in proteinuria Decreased urate clearance – increased serum uric acid levels Oliguria and ARF Need to balance adequate preload without causing pulmonary oedema

Pathophysiology - CNS Headache Visual disturbance Confusion Generalised hyper-reflexia Cerebrovascular haemorrhage Eclampsia – resulting from celebral oedema or cerebrovascular vasoconstriction

Pathophysiology – Fetoplacental Unit Poor placental perfusion – increased resistance in spiral arteries Reduced fetal growth with associated olighydramnios Basically Multisystem disorder Patients with severe pre-eclampsia can be thought to have total body oedema

Management Domain of obstetricians Control hypertension – prevent maternal morbidity Methyldopa – safe in pregnancy Nifedipine B-blockers in third trimester (labetolol preferred) – prolonged use may decrease fetal growth Hydralazine – for acute reduction Avoid ACE inhibitors – associated with oligohydramnios, still birth, neonatal renal failure

Management Treat seizures – magnesium sulphate Severe pre-eclampsia/eclampsia A,B,C’s Appropriate fetal and maternal monitoring etc.. Term delivery ideal – risk of morbidity associated with pre- eclampsia and risks of a pre-term delivery Aim to stabilise symptoms long enough to mature fetal lungs In established pre-eclampsia the only definitive treatment is the delivery of the placenta.

Anaesthetic Implications Pain management during labour Regional anaesthesia for surgical delivery GA for surgical delivery

Anaesthetic Implications - Labour Epidural Traditionally considered anaesthetic of choice Controls excessive surges in BP Decreases circulating stress-induced catecholamines and uterine vascular resistance Check platelet count Beware of fluid preloading prior to insertion in patients with pulmonary oedema Monitor BP and fetus carefully and treat BP promptly with ephedrine (expect increased effect)

Anaesthetic Implications - Spinal Spinal Anaesthesia Evidence based studies limited Use controversial – risk of profound maternal hypotension and uteroplacental hypoperfusion Theoretical advantage of epidural weighed against known benefits of spinal ie. greater reliability, less procedural time, less epidural vascular trauma Check platelets, reduce preload volume, ephidrine etc

Anaesthetic Implications - GA General Anaesthesia Only if regional anaesthesia cotraindicated or precluded by urgency of need for delivery Endotracheal intubation more difficult in pregnant population, plus oedema of upper airway, therefore prepare for difficult intubation Exaggerated hypertensive response to laryngoscopy – significant morbidity RSI If magnesium used – expect prolongatin of action of muscle relaxants Normal dose of suxamethonium, titrate non-depolarising muscle relaxants Avoid NSAIDs for post-op analgesia

Take Home Message Usually multisystemic involvement Risk of significant obstetric and anaesthetic complications Anaesthetic risks reduced by Early communication and preparation Early placement of epidural catheter Utilising spinal for urgent C-section if no epidural in place GA only when regional anaesthesia contraindicated Anticipate difficult airway Emphasis on preoperative baseline BP reduction and blunting hypertensive response to laryngoscopy