Malignant Hyperthermia PHUONG PHAM

Transcription

1 Malignant Hyperthermia PHUONG PHAM

2 Objectives Pathophysiology Diagnosis Management Clinical roles Aftermath

3 Epidemiology 1: : 4500 M > F non-triggering agents triggering agents used 52% MH reactions occur in paediatrics

4 Excitation-Contraction Coupling

5 Pathophysiology

6 Clinical Diagnosis EARLY LATE Masseter spasm Cola coloured urine ETCO2 Muscle ache Tachypnoea CK Tachycardia Coagulopathy Cardiac arrest DEVELOPING Temp 0.5⁰C per 15min Acidosis Hyperkalaemia Diaphoresis CVS instability SpO2 or skin mottling Generalised muscle rigidity

7 Differential Diagnoses Inadequate anaesthesia Sepsis Thyroid storm Recreational drugs Phaeochromocytoma Neuroleptic malignant syndrome Intracerebral pathology

8 Initial Management Declare emergency Call for HELP Send for MH box & refrigerated supplies Turn off volatiles and remove vaporisers from machine Hyperventilate with 100% O2 and 15L/min Commence TIVA Allocate task cards Give DANTROLENE

9 Theatre Coordinator Call for additional anaesthesia support Call senior surgeon if required Mobilise off-site dantrolene Organise transfer of additional stocks Organise transfer to ICU Consider rescue helicopter (AVR)

10 Anaesthetic Assistant Lay out contents of MH box & refrigerated supplies Prepare arterial-line equipment Assist with dantrolene mixing Maintain resuscitation & TIVA drugs supply Set up CVC equipment Ensure volatile agent removed from OT Change soda lime when required

11 Local supply 24 vials in MH Box BBH 12 vials St John of God ICU 12 vials Howitt St. Day Surgery Centre 2.5mg/kg (ie: 175mg) Repeat every 10-15min minute 4 boluses = 700mg Each vial of dantrolene = 20mg (ie: 9 vials) 4 boluses = 35 vials Each 20mg mixed with 60ml of sterile water DANTROLENE

12 1 vial Mode of action Orange 20mg dantrolene sodium 3g mannitol Sodium hydroxide ph 9.5 Inhibit ryanodine receptors in sarcoplasmic reticulum Ca ion release is inhibited Skeletal muscular contraction is reduced to a given electrical stimulus Administered IV Repeated every 10-15hrs Total dose 30mg/kg

13 Cooling Room temperature Ice packs Refrigerated IVF Cool sponges Intra-abdominal lavage Collect defibrillator

14 Scribe Document events during critical crisis

15 Anaesthetist 1: Resuscitation Dantrolene Maintenance of anaesthesia Management Hyperkalaemia Arrhythmia Acidosis Renal protection Inotropic support

16 Anaesthetist 2: Lines & Ix Temperature probe Arterial line Regular ABGs Bloods: UEC, CK, Coags CVC Urine sample: myoglobin Maintain urine output 2ml/kg/hr Document

17 Surgical Team Complete or abandon surgery Call for senior help if needed Help cool patient Expose patient Abdomen washout N/S at 4⁰C Pack body with ice bags Insert IDC

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19 Subsequent Testing In Vitro Contracture Test (IVCT) Quadicepts muscle biopsy Caffeine & halothane Four sites Royal Melbourne Hospital Royal Perth Hospital Westmead Children s Hospital Palmerston North Hospital Genetic Testing Track a specific mutation Known IVCT positive family member 50% of IVCT positive will have mutation identified Cannot prove person does not have MH Sensitivity 99% Specificity 93.6%

20 Anaesthesia for the Susceptible Nitrous oxide Barbiturates Propofol/TIVA Opiates NDMR Anaesthesia machine cleansing 5 parts per million of volatile anaesthesia FGF 10L/min Regional

21 References Department of Anaesthesia and Pain Management at The Royal Melbourne Hospital. Malignant Hyperthermia. [Accessed 21/02/2016] < Smith S, Scarth E, Sasada M Drugs in Anaesthesia and Intensive Care. 4 th ed. Oxford: Oxford University Press. p Zhou J, Bose D et al Malignant hyperthermia and muscle-related disorders. In: Miller RD, Cohen NH et al, editors. Miller s Anesthesia. 8 th ed. Philadelphia: Elsevier. p.128

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