Malignant Hyperthemia

Question 1

What is the mechanism of Malignant Hyperthermia?

Answer 1

The ryanodine receptor in skeletal muscle is abnormal -> interferes w/ regulation of calcium in the muscle.

An abnormal ryanodine receptor that controls calcium release causes a buildup of calcium in skeletal muscle, resulting in a massive metabolic reaction

Question 2

Name the Early METABOLIC signs of MH

Answer 2

tachypnea
hi CO2 production
increased O2 consumption
combination of metabolic and respiratory acidosis
profuse sweating and mottling of skin

Question 3

Name the early CV signs of MH

Answer 3

Tachycardia
arrhythmias

Question 4

Name the early MUSCLE signs of MH

Answer 4

Masseter spasm if succinylcholine has been given
generalized muscle rigidity

Question 5

Name the LATE signs of MH

Answer 5

Rapid increase in core temperature (1-2 degrees Celsius every 5 minutes)
rhabdomyolysis
grossly elevated blood CPK and myoglobin levels
darkly colored urine
hyperkalemia
severe cardiac arrhythmias
DIC

Question 6

What is the TX for MH?

Answer 6

Dantrolene (Ryandex)

Question 7

Dantrolene (Ryandex) indication/usage?

Answer 7

Skeletal muscle relaxant indicated for:
- tx of MH in conjunction of supportive care
- prevention of MH in HI risk patients

Question 8

What is the MOA for Dantrolene?

Answer 8

decreases the loss of Ca++ from the sarcoplasmic reticulum in the skeletal muscle and restores normal metabolism

Question 9

How to mix Dantrolene?

Answer 9

= Available in 250 mg vial for reconstitution

= Reconstitute w/ 5 mL preservative free sterile water for injection (WITHOUT bacteriostatic agent)
- do NOT reconstitute w/ any other solution

= Shake vial: ensure orange-colored uniform suspension

= visually inspect vial for particulate matter and discoloration

= final concentration: 50 mg/mL
- MUST be used w/in 6 hours of reconstitution
- store at room temperature

Question 10

Dosing of Dantrolene

Answer 10

Prevention of MH in HI risk pts
- 2.5 mg/kg IV over at least 1 minute, beginning 75 minutes prior to surgery w/ additional doses prn

CRISIS situation
- initial dose is 2.5 mg/kg rapidly thru large-bore IV, if possible

• repeat every 5 minutes until the patient responds w/ decrease in ETCO2, decreased muscle rigidity, and/or lowered heart rate up to 10mg/kg is reached
• large doses (> 10 mg/kg) may be required for patients with persistent contractures or rigidity

POST crisis follow-up

• 1 mg/kg every 4 - 6 hours IV/oral or a continuous IV infusion of 0.25 mg/kg/hr for atleast 24 hours; further doses may be indicated

Question 11

How ADMINISTER Dantrolene?

Answer 11

IV PUSH into IV catheter while an IV infusion of 0.9% NS or D5W injection is freely running

            OR

IVP into the indwelling catheter after assuring patency w/out freely running infusion. Flush line after administration to ensure there is no dantrolene remaining in the catheter

CENTRAL LINE PREFERRED
- reconstituted pH 10.3 - caution to avoid extravasation

MHAUS recommends that administration of Dantrolene begin w/in 10 minutes of recognizing MH

Question 12

What are the precautions of Dantrolene?

Answer 12

Skeletal muscle weakness
- ambulate w/ assistance until normal muscle strength and balance is restored

Dyspnea
- monitor for adequacy of ventilation

Dysphagia
- assess for difficulty swallowing and choking

Somnolence and Dizziness
- can occur and persist up to 48 hours post-dose

Tissue Necrosis w/ extravasation
- due to HI pH of reconstituted solution
- prevent leakage into surrounding tissue

Use in combination w/ CCB (cardizem, nicardipine, verapamil) may result in CV collapse w/ marked hyperkalemia (K+)

Question 13

What to do in ACTUTE Tx?

Answer 13

BEGIN TX ASAP as MH is suspected

1. Notify MD/Anesthesiologist if pt is in post-op
2. Get Dantrolene/MH cart
3. Call for help and obtain MH cart ASAP
   - If MH cart is not stored in your unit call your covering unit per coverage list
4. Call MH hotline 800-644-9737 for additional advice
5. Hyperventilate w/ 100% fiO2 using 2-3x NL minute volume
6. Admin Dantrolene
   - repeat until s/sx are reveresed

Question 14

Other Acute Tx?

Answer 14

Cool patient
- cold IV fluids and skin surface by applying ice packs to groin, axillae and head

Monitor and/or tx dysrhythmias and hyperkalemia

Monitor:
- core temp
- UOP w/ bladder catheter
- arterial and/or central venous if warranted
-ETCO2
-HR
-Electrolytes
-CK and urine myoglobin
- coagulation studies

Question 15

Name the Team Members and assigned responsibilities/tasks

Answer 15

Circulating/Charge RN
- calls for help (OR desk or MHAUS hotline)
- notifies other anesthesia in charge
- initiates the MH protocol
- delegates roles to other team members

Dantrolene RN
- obtains MH and/or crash cart
- starts mixing Dantrolene
- organizes assistants (ECT PCTs & clinicians)

Medication RN
- focuses on assisting anesthesia provider in treating hyperkalemia, acidosis, arrhythmias
- be prepared to give ACLS medications and follow protocols
- keeps records

COOLING RN
- gathers/retrieves cooling supplies
- cools patient skin surfaces by applying ice packs to groin, axillae and head
- be prepared to lavage stomach, bladder, and rectum with cold saline
- insert foley catheter, monitor hemodynamic status, and I/O