MDHB News

Malignant Hyperthermia Anaesthetic Technicians

The Malignant Hyperthermia (MH) anaesthetic technician has an important role in screening for MH susceptible patients and in the maintenance of equipment related to MH.

Malignant Hyperthermia Testing

Each theatre list and where possible each emergency is screened for known MH susceptible family names. A computerised program enables this and susceptible names are highlighted on each operating list.

The anaesthetic technician is responsible for the maintenance of the vapour-free anaesthetic machine, the MH emergency cart, replacing used stock such as dantrolene and checking the supply of resuscitation drugs and appropriate fluids such as normal saline at 4^oC.

In recent years DNA analysis has developed into an important part of MH investigation and the anaesthetic technician is responsible for maintaining stocks of storage vials and assisting in collection of specimens. The technician is also responsible for notifying administrative personnel of results of positive investigations. A national "alert' is then placed on the notes of the appropriate patient.

The anaesthetic technician has an educational role with other theatre staff - use of databases, preparation of drugs, the technician's role in the management of an MH crisis.

Susceptibility

Checking of names for MH Susceptibility:

Booked List Cases:

As assistants to the anaesthetist, anaesthetic technicians are responsible for the checking the surnames of people having operations the next day, then all names that may be MH related are highlighted. Children have the father and mother’s susceptibility checked.
The anaesthetists are therefore made aware and obtain the necessary family history from the patient.
MH names are found on the computer database which is only accessible by the technicians and anaesthetists at Palmerston North Hospital.
There is a manual system still available for the family trees in relation to MH as a back-up should the computer fail.

Acute Cases:

Patients who come for acute surgery have their names checked by the technician on duty and if name is associated with MH, the anaesthetist is informed and they check out susceptibility.
If an association is suspected, an agent free anaesthetic machine is available and used.
With monitoring and the appropriate equipment a trigger free anaesthetic is given.
People with MH negative biopsies are given a normal anaesthetic.

If any assistance is required in regard to Malignant Hyperthermia susceptibility, contact Palmerston North Hospital – Operating Theatre [06 350-8500] and ask for the Consultant Anaesthetist on call.

Set-Up Equipment for Malignant Hyperthermia Patient - Anaesthetic Technician Guidelines

Trigger Free General Anaesthetic

Anaesthetic Machine

Agent Free machine
“Clean Machine” (Anesthesiology 69:395) - Maccani and Wedel demonstrated that prolonged exposure of MH susceptible swine to 5ppm halothane failed to trigger MH. This can be regarded as a safe concentration. Removal of vaporizer, absorber, circle tubing and fresh gas hosing and flushing for 10 minutes with 100% oxygen reduces concentration of agent at the fresh gas hosing outlet to <5 ppm. Retaining the fresh gas hosing doubles the washout time. Intact bellows makes no significant difference to the outlet concentration.

A279
October 18, 2008
2:00 PM - 4:00 PM
Room Hall E2-Area N,

Preparation of the Datex-Ohmeda Aestiva Anesthetic Machine for Malignant Hyperthermia Cases

Kelly S. Shinkaruk, M.D., Kevin Nolan, M.D., F.R.C.P.C., Marylou Crossan, B.S. Anesthesiology, University of Ottawa, Ottawa, ON, Canada

Purpose: Current guidelines for preparing anesthetic machines for malignant hyperthermia susceptible patients were outlined based on studies looking at older models. The newer generation Datex-Ohmeda Aestiva anesthetic machine was studied in order to determine the washout profile of sevoflurane and to establish new guidelines for its preparation.

Technical Features: Initially, sevoflurane was run at 2% (MAC) for two hours. After priming, the anesthetic machine was prepared as per institutional guidelines for a malignant hyperthermia susceptible patient. Fresh gas flows were increased to 10L/min and circuit and gas analysis tubing was replaced with new tubing; a MIRan infrared gas analyzer was utilized to determine sevoflurane concentration in ppm every minute until a concentration below 5ppm was attained. Following this procedure, it was determined that sevoflurane washout time in an Aestiva anesthetic machine was 52 to 59 minutes with a 95% confidence interval.

Conclusion: Given these results, it is concluded that the Aestiva machine must be flushed with a fresh gas flow of 10L/min for at least 55min in order to achieve a sevoflurane concentration of less than 5ppm.

Anesthesiology 2008; 109 A279

Monitoring

Usual monitoring with the addition of intra-operative tympanic temperature monitoring and Nasal CO₂ Monitoring postoperatively

Reusable/Non Reusable items

Most airway equipment is disposable, including Laryngeal Masks. The only items recycled are metal Laryngoscope blades. These are processed/decontaminated in the Steris System.