Clinical Signs of MH
What makes you suspect that a patient is having an MH crisis rather than another reaction in the OR?
Three symptoms. Early symptoms include: Muscle Rigidity, Increased HR (arrhythmias), Increased ETCO2
Name at least 2 medications that are safe to use during anesthesia with MH susceptible patients:
The following agents have been identified as the safest to use on MHS patients:
• Droperidol
• Benzodiazepines
• Ester-type local anesthetics
• Thiopental sodium and pancuronium: These seem to be protective agents, since they raise the triggering threshold for MH.
• Nitrous oxide and ketamine hydrochloride are categorized as weak-triggering agents and therefore, are considered safe for use. The prophylactic IV administration of dantrolene prior to the surgical procedure is not considered necessary if safe anesthetics are used.
What is the initial priorities in an MH crisis for the anesthetist, surgeon & nurses.
Anesthetist: Stop triggering agent, hyperventilate with 100%O2
Surgeon: Close/End procedure as quickly as possible
Nursing: Call Code, Get Dantrolene (MH Cart)
Why is mannitol or furosemide given?
Muscle cells are destroyed during an MH crisis and the myoglobin that is released accumulates in the kidneys, obstructing urinary flow, referred to as myoglobinuria. Diuretics are given IV to promote and maintain urinary flow in order prevent renal damage. Mannitol 0.25g/kg IV; furosemide 1mg/kg IV; up to four doses each. Urinary output of 2ml/kg/hr or higher must be maintained to prevent renal failure.
What is the dose of Dantrolene mg/kg?
What is 2.5 mg/kg
-dark, brown urine
-bleeding/oozing from wound sites
-dark blood in operative field
-temperature elevation
What do these symptoms tells you about an MH Crisis
Late Symptoms- the MH crisis has progressed resulting in hyperthermia and muscle cell breakdown
How many dantrolene sodium vials (Dantrium) need to be available? How much sterile water is required for mixing?
What is 36 vials/ 60ml Sterile Water
Why do patients exhibit an increase in temperature during an MH crisis?
Triggering agent --> genetic muscle receptor abnormalities lead to the SR in the skeletal muscle to release excessive calcium --> muscle contraction and rigidity --> increase metabolism + generate heat.
Sodium Bicarb is requested by the anesthetist during an MH crisis. What is the anesthetist looking to treat?
Acidosis
Where is Sodium Bicarb located?
What do these diseases have in common?
Put people at higher risk of developing MH
A Systematic review of Level 1 evidence published in 2013 showed patients are not at risk of an MH crisis if they do not receive a triggering agent. This is why changes have been made in PACU discharge practices.
GROUP JEPOARDY: How many mg of Dantrolene (Dantrium) do you get in each vial? What else is in a Dantrolene vial?
Danrolene 20 mg
Mannitol 3g
How many nurses are required to prepare Dantrolene? What are their roles?
At least 2 (more is helpful)- one reconstitutes Dantrolene, the other prepares 60ml syringes of sterile water
In an MH Crisis Esmolol, Lidocaine, Procainamide are drugs used to treat
arrhythmias
You have called an MH crisis overhead and an ED nurse comes. How do you direct them?
Depending on the situation- may mix Dantrolene
Starting a second, large bore IV site + Bloodwork
Central Line
What do you tell a nursing student who tells you MH is best characterized by an increase in temperature.
this is a classic, yet late symptom of MH. (why?)
How long does the anesthetic machine need to be purged with 100% oxygen? What flow of oxygen?
What is 35 minutes / 15 L Flow
How do we treat extreme increases in temperature? What temperature are we aiming to cool to?
Cool patient: Ice packs, Ice, Frozen IV Bags/ Cooled IV Fluids
38 degrees
What is the mechanism of Dantrolene?
The effect of the therapeutic agent dantrolene is to decrease the release of Ca+ from the Sarcoplasmic Reticulum (SR) and increase re-uptake of Ca+ by the SR.
Since Dantrolene has become available, mortality from MH has declined from greater than 50% to less than 10%.
How does the anesthetist know how to titrate the amount of Dantrolene the patient receives?
Depending on patient symptoms. Dantrolene is administered repeated as frequently as needed until the patients responds with a decrease in ETCO2, decreased muscle rigidity, and/or decreased heart rate
GROUP JEPOARDY: Name any unmentioned symptoms to watch for
What is Cyanosis, Skin Mottling (70%), Unstable BP, Respiratory and/or metabolic acidosis, Abnormal Lab tests, Myoglobinuria, Tachypnea
What must be removed from the gas machine before flushing?
What is Vaporizing module! Old soda lime, circuit tubing, rebreathing bag and all equipment set out on gas machine
What are signs you are monitoring for when administering Dantrolene IV?
A blown IV site: Erythema & edema
Dantrolene can cause tissue necrosis due to its high pH.
Your patient requires an mini-bag infusion. What type of crystalloid do you choose for your primary line?
NaCL (not lactated ringers)
What is the dose and how long should dantrolene be given post MH reaction?
1 mg/kg IV Q6H for 24 - 48 hours