Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
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