Malignant Hyperthemia Flashcards
What is the mechanism of Malignant Hyperthermia?
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
Name the Early METABOLIC signs of MH
tachypnea
hi CO2 production
increased O2 consumption
combination of metabolic and respiratory acidosis
profuse sweating and mottling of skin
Name the early CV signs of MH
Tachycardia
arrhythmias
Name the early MUSCLE signs of MH
Masseter spasm if succinylcholine has been given
generalized muscle rigidity
Name the LATE signs of MH
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
What is the TX for MH?
Dantrolene (Ryandex)
Dantrolene (Ryandex) indication/usage?
Skeletal muscle relaxant indicated for:
- tx of MH in conjunction of supportive care
- prevention of MH in HI risk patients
What is the MOA for Dantrolene?
decreases the loss of Ca++ from the sarcoplasmic reticulum in the skeletal muscle and restores normal metabolism
How to mix Dantrolene?
= 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
Dosing of Dantrolene
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
How ADMINISTER Dantrolene?
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
What are the precautions of Dantrolene?
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+)
What to do in ACTUTE Tx?
BEGIN TX ASAP as MH is suspected
- Notify MD/Anesthesiologist if pt is in post-op
- Get Dantrolene/MH cart
- Call for help and obtain MH cart ASAP
- If MH cart is not stored in your unit call your covering unit per coverage list - Call MH hotline 800-644-9737 for additional advice
- Hyperventilate w/ 100% fiO2 using 2-3x NL minute volume
- Admin Dantrolene
- repeat until s/sx are reveresed
Other Acute Tx?
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
Name the Team Members and assigned responsibilities/tasks
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
