Download Update 11 - Update in Anaesthesia - WFSA

22Update in AnaesthesiaFigure 7: Sinus tachycardiaHeart failureThyrotoxicosis Drugs eg atropine, ether, ketamine, catecholaminesManagement : correction of any underlying cause wherepossible. Beta blockers may be useful if tachycardia causesmyocardial ischaemia in patients with ischaemic heartdisease, but should be avoided in asthma and used withcaution in patients with heart failure.Sinus bradycardia (figure 8).This is defined as a heart rate of less then 60 beats/minutein an adult.It may be normal in athletic patients and may also be dueto vagal stimulation during surgery - see above.Other causes include: Drugs eg; beta blockers, digoxin,anticholinesterase drugs, halothane, second doseof suxamethonium (occasionally first dose inchildren)Myocardial infarctionSick sinus syndromeRaised intracranial pressureHypothyroidism HypothermiaManagement It is often not necessary to correct a sinusbradycardia in a fit young person, unless the rate is lessthan 45 - 50 beats per minute, and / or there ishaemodynamic compromise. However consider:Correcting the underlying cause eg: stop the surgicalstimulus Atropine up to 20 mcg/kg iv or glycopyrolate 10mcg/kg iv. (Atropine works more rapidly and isusually given in doses of 300-400mcg and repeatedif required).Patients on beta blockers may be resistant toatropine - occasionally an isoprenaline infusion maybe required. Alternatively glucagon (2-10mg)can be used in addition to atropine.ARRHYTHMIAS DUE TO RE- ENTRY (Circularmovement of electrical impulses).These arrythmias occur where there is an anatomicalbranching and re-joining of a conduction pathway.Normally conduction would occur down both limbsequally. But if one limb is slower than the other, an impulsemay pass normally down one limb but be blocked in theother. Where the pathways rejoin the impulse can thenFigure 8: Sinus bradycardia