1.22 Malignant Hyperpyrexia

Question 1

Causes of hypercapnia under GA

Answer 1

Alveolar hypoventilation

• obstruction
• Opioids
• Dead space

Rebreathing

• failure soda lime
• low fgf

Sepsis / ARDS

Asthma
Bronchospasm

Hypermetabolic states

• MH
• Pyrexia
• hyperthyroid

Inappropriate Minute Ventilation settings

Question 2

Diagnosis of MH

Answer 2

Unexplained Rise in EtCo2 +:

Unexplained tachycardia

Unexplained Increased in O2 consumption

Presence of generalised muscle rigidity
-Masseter spasm

Question 3

Immediate management

Answer 3

1. Call for help
2. Assess ABC 100 O2
3. Limit hypermetabolic process
   turn off inhaled volatile
   replace breathing circuit / filters
4. Maintain Anaesthesia with IV agents
5. Hyperventilate
6. IV dantrolene
   2-3mg/kg
   then 1Mg /kg PRN
7. Initiate active cooling
   - cold fluids
   - Ice packs axillae / groin
   - Cold bladder ng + peritoneal irrigation
   - Extracorporeal heat exchange

Question 4

Ongoing Management

Answer 4

Monitoring
Standard AAGBI

Invasive
A line
CVP

Urinary catheter
Urinary Ph

Measure core + peripheral temp

Blood tests
ABG
FBC U+E incl CK
Coag

Specific Rx

HyperK:
IV Ca Cl / Gluc
insulin dex
Soda bic

Forced alkaline diuresis ?rhabdom / myoglobinuria

Blood products PRN

Mg Amio to Rx arrhythmias
Ca channel blocker C/I dantrolene interaction

Question 5

Further management

Answer 5

Rx ICU
Further dantrolene

Continue monitor signs
RF
? Rhabdom
? compartment syndrome

Consider DDx recreation drugs / sepsis / endo tumour

R/F to MH unit for further testing

Question 6

Diagnosis of MH Susceptibility

Answer 6

confirmed either through
genetic testing

or

a muscle biopsy with
in vitro contracture tests (IVCT) of
the excised muscle

Prof. T. McCarthy
Irish Malignant Hyperthermia Diagnostic Centre
Department of Biochemistry
University College Cork

Question 7

How to prep workstation

Answer 7

• Remove vaporisers from anaesthetic workstation

• Flush circuit with oxygen and/or
air with maximum flow rate, for 90 s

• Insert activated charcoal filters
(ACFs) on both inspiratory and expiratory limb

• Change anaesthetic breathing circuit
(T-, circle circuit, reservoir bag) and soda lime
canister for uncontaminated equipment