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22 Cards in this Set
- Front
- Back
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What is MHS? |
Malignant Hyperthermia Susceptibility. An Autosominal dominant genetic disorder of the ryanodine receptor (RYR1) calcium channels with crises triggered in susceptibility individuals. |
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Mode of Transmission: Autosomial Dominant Inheritance |
Dominant: only one mutated gene of a pair is required to posses a trait. Therefore, off spring of patient with MH have 50% chance of inheriting the gene. |
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MHS: Pathophysiology |
Trigger agents cause calcium gated channels to open more easily and stay open longer (leaky channel syndrome) ■ Elevated intracellular calcium levels cause sustained muscle activity, muscle cell metabolism leading to enhanced O2 consumption and heat production. |
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MHS: Early Signs |
■ Prolonged masseter spasm ■ Hypercarbia (80mmHg) ■ Unexplained tachypnoea ■ Unexplained tachycardia ■ Cardiac Arrhythmias (ectopic beats) |
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MHS: Developing Signs |
■ Rapid rise in temp - 0.5 degree/15mins ■ Metabolic acidosis ■ Hyperkalaemia ■ Cardiovascular instability ■ Desaturation ■ Generalised muscular rigidity |
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MHS: Later Signs |
■ Coloured urine - due to myoglobinuria ■ Generalised muscle ache (in awake patient) ■ Coagulopathy ■ Cardiac Arrest |
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What is prolonged Masseter Spasm? |
■ True masseter muscle spasm occurs when "jaws of steel" make mouth opening impossible (for at least 2mins) ■ over 50% of patients will subsequently prove to be MH susceptible. |
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MHS: Non anaesthetic triggers |
■ Stenuous exercise ■ Stress ■ Heat Stroke ■ Muscular Dystrophy |
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MHS: Anaesthetic Triggers |
■ Volatile inhalational agents ■ Halo ■ Iso ■ Des ■ Sevo ■ Depolarising muscle relaxants ■ Sux |
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MH Complications |
■ Disseminated Intravascular coagulation (DIC)- widespread activation of the clotting cascade. ■ Pulmonary Oedema ■ Acute Renal Failure ■ Blindness ■ Seizures ■ Paralysis ■ Cardiac Arrest |
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MHS: Confirmation testing |
■ Blood clotting studies - prothrombin time ■ Urine Analysis: presence of myoglobin (protein) |
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MHS: Diagnosing MHS |
■ Muscle Biopsy: caffein hallothane contracture test (CHCT) ■ Genetic Testing - DNA Analysis - only detects 30% |
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What is the caffien halothane contracture test? |
■ Standard for MH diagnostic testing ■ Used to determine patients MH susceptibility |
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CHCT: Procedure and result |
■ Biopsy of Vastus lateralis 3.5cm long, 2cm wide, 1.5cm deep. (under LA) ■ Biopsy is exposed to caffeine of Halothane separately and the rate and force of contraction recorded electronically. Result: MH susceptible muscle is more sensitive and contracts with greater sustained force than normal muscle. |
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MH trolley contents |
∆ 24x 20mg vials of Dantrolene ∆ drawing up needles ∆ 2000ml sterile water ∆ 50ml syringes (5-10) ∆ task cards ∆ urinary catheter |
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MH trolley contents: drugs |
8.4% sodium bicarbonate 50% dextrose 50ml Lignocaine 1% Amiodarone 300mg |
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MH trolley contents: cool box in fridge |
∆ 2L normal saline ∆ actrapid insulin |
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MH trolley contents: blood sample tubes |
•Haematology •Coagulation profile •Electrolytes •Cross match •Blood gas syringes |
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MH trolley contents: monitoring |
Art line equipment Central line equipment Temperature probe |
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MH resource kit contents |
•MH introduction •MH crisis initial management •MH task cards •MH education poster (you've only got a few mins) •Recommendations for contents •Guidelines for management |
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Crisis cards |
1) coordinator 2) anaesthetist 1: resus 3) Dantrolene 4) anaesthetic tech 5) anaesthetist 2: lines & investigation 6) cooling 7) surgical team 8) logistics |
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Anaesthetic tech role |
1) layout trolley contents 2) prepare and assist with art line 3) assist with Dantrolene mixing 4) ensure adequate stocks 5) prepare & assist with central line. 6) ensure volatile agent is removed 7) change sida lime when required |
