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Download Anaesthetic Management Of Delivery In Patients With Heart Disease
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Anaesthetic Management Of Cardiac Patients Dr Jeremy Corfe Consultant Anaesthetist Norfolk and Norwich University Hospital CVS Physiology CVS Physiology in Pregnancy Roos-Hesselink JW, Duvekot JJ, Thorne SA. Pregnancy in high risk cardiac conditions. Heart 2009; 95: 680-6 Cardiac Output in Labour CO increase: - Latent phase: 15% 1st Stage: 25% 2nd Stage: 50% 3rd Stage: 80% - CO = SV x HR 1st Stage Cardiac Output • ⇧ HR - sympathetic • ⇧ SV - autotransfusion • ~ 500ml per contraction • ⇧ BP with contractions • Systolic 15-25% • Diastolic 10 -15% • Epidurals help 2nd Stage Cardiac Output • 2nd Stage • ⇧ Circulating Oxytocin (Ferguson’s reflex) • ⇧ strength contractions = ⇧ autotransfusion • ⇧ HR • Active pushing – Valsalva 3rd Stage Cardiac Output • 3rd Stage increase in CO • Autotransfusion from contracted Uterus ≤ 1500ml • Aortocaval compression removed • Offset by normal blood loss at delivery • Furosemide is useful Pharmacology in labour Tocolytics • β2 agonists – Terbutaline, Salbutamol, Ritodrine • ⇧ HR Tocolytics • β2 agonists – Terbutaline, Salbutamol, Ritodrine • Nifedipine • ⇩ SVR + ⇩ BP with reflex ⇧ HR + ⇧ Contractility • ≤40mg in 1 hour, followed by 20mg SR TDS • Normal antihypertensive dose 20mg / day Tocolytics • β2 agonists – Terbutaline, Salbutamol, Ritodrine • Nifedipine • Atosiban • Oxytocin receptor antagonist • Animal studies = no effects on HR, contractility or BP • Drug of choice in cardiac patients? • Availability? • £52 per vial. Uterotonics • Oxytocin • Used for • Augmentation of labour • 1st line prophylaxis & treatment of uterine atony • Immediate onset, short duration – 5 minutes • Weak ADH effect Uterotonics • Oxytocin • Case reports of • Chest pain • Ischaemic ECG changes • Cardiac arrest • Why? Uterotonics • Oxytocin • CVS effects • ⇩ SVR • ⇧ HR + ⇧ SV = ⇧ CO Langesæter E et al. Br. J. Anaesth. 2009;103:260-262 Uterotonics • Oxytocin • CVS effects • ⇩ SVR • ⇧ HR + ⇧ SV = ⇧ CO • Effects worse with • IV bolus • 10U vs 5U Thomas J S et al. Br. J. Anaesth. 2007;98:116-119 Uterotonics • Oxytocin strategies in high risk patients • GIVE SLOWLY • 5U “bolus” via pump over 10 – 15 minutes • Or avoid bolus & titrate infusion to effect • Use concentrated solutions for postpartum regime Uterotonics • Ergometrine • Direct effect on smooth muscle - ⇧ uterine tone • Half life 30 – 120 minutes • Effects last approximately 3 hours • Works well • But..... Uterotonics • Ergometrine • Also acts on α1, D2 & 5HT2 receptors • Vasoconstriction – systemic & pulmonary hypertension • Coronary artery spasm • Bronchospasm • Vomiting Uterotonics • Ergometrine • Contraindicated in • Pre-eclampsia • Coronary artery disease • Aortopathies • Aneurysms Uterotonics • Prostaglandins • PGE1 & PGE2 – Misoprostol & Dinoprostone • PGF2α – Carboprost • Diarrhoea, vomiting, pyrexia, shivering • Haemodynamic effects dependent on type • Misoprostol - vasodilatation • Carboprost - vasoconstriction Uterotonics • Prostaglandins - Misoprostol (PGE1) • 800mcg PR • Not as effective as Oxytocin or Ergometrine • Limited haemodynamic effects • Beware of shivering • Best for cardiac patients? Uterotonics • Prostaglandins - Carboprost (PGF2α) • Normally the drug of choice for refractory uterine atony • BUT • Bronchospasm • ⇧ Pulmonary shunt • ⇧ PVR & ⇧ PAP • SVR • Contraindicated in • Asthmatics • Single ventricle • Pulmonary hypertension Uterotonics: order of use in high risk patients 1. Oxytocin 2. Misoprostol • Beware of shivering Only proceed if life threatening PPH, consider physical measures first 3. Carboprost • Do NOT give to single ventricle, ⇧PAP, shunt, asthmatics 4. Ergometrine • Do NOT give to pre-eclamptics, aortopathies, aneurysms coronary artery disease Other drugs • Labetolol & Hydralazine • MgSO4 • Dexamethasone / Betamethasone • Na+ + H2O retention Common Anaesthetic agents • Induction agents – Propofol / Thiopentone • Negative inotropes • ⇩ SVR • Maintenance – Isoflurane, Sevoflurane, Desflurane • Mild negative inotropes • ⇩ SVR • Dose dependent tocolytic effect Other commonly used Anaesthetic drugs • Vasopressors • Phenylephrine • Potent α1 agonist • Maternal bradycardia • Anticholinergics • Glycopyrolate / Atropine • Ephedrine • Direct β1 + indirect α1 • Fetal effects Analgesia & Anaesthesia Analgesia & Anaesthesia • 1st stage: T9-L1 • 2nd stage: S2-S4 • Operative delivery • Rectus muscles & parietal peritoneum innervated up to T6 • Block above T4 may block cardiac accelerator fibres Epidural Analgesia • Advantages • Great analgesia • Abolishes sympathetic response to labour • Can be topped up for operative anaesthesia Epidural Analgesia • Disadvantages • Sympathetic block - vasodilatation and ⇩ SVR • Normally well tolerated • Avoid with low dose incremental dosing +/- filling & vasopressors • Beware fixed output states and R>L shunts • Increased risk instrumental delivery • Timing of anticoagulants Remifentanil PCA for labour analgesia • Ultra short acting potent intravenous opioid • Rapidly metabolised by mother and baby • Does not accumulate • Can be used when epidural contraindicated • But • Analgesia inferior to epidurals • Will not completely block sympathetic effects of labour Operative Delivery – Regional Anaesthesia • Preferred to general anaesthesia • Avoids management of more difficult obstetric airway • Greater patient satisfaction • Effects as epidural analgesia - vasodilatation and ⇩ SVR • More profound & quicker onset (Spinal > CSE > Epidural) • Use • Arterial line before insertion • Low dose CSE technique / slow epidural top up General Anaesthesia • Advantages • Quick • Useful in very anxious patients • Allows certain therapeutic interventions • DC cardioversion, 100% O2, post op ventilation • Only option if anticoagulated General Anaesthesia • Disadvantages • Difficult obstetric airway • Hypotension – induction / maintenance • Hypertension & tachycardia – intubation / extubation Connell et al. Can J Anaesth 1980; 27: 389-94 General Anaesthesia • Disadvantages • Difficult obstetric airway • Hypotension – induction / maintenance • Hypertension & tachycardia – intubation / extubation • Arterial line • Cardiostable anaesthetic – lots of opiates • Reduced patient satisfaction • Inferior analgesia, PONV Summary Summary Summary Summary • Order of use of Uterotonics in high risk patients: 1. Oxytocin 2. Misoprostol Only proceed if life threatening PPH, consider physical measures first 3. Carboprost 4. Ergometrine Summary • Anaesthetic agents and techniques • Regional is preferred • All cause ⇩ SVR • Spinal > GA > epidural • Arterial line and low dose CSE works well • Consider anticoagulant timing
