OVERVIEW LEARNING OBJECTIVES

© 2014 Progressive Surgical Solutions, LLC

Ma

ligna

nt

Hyp

ert

herm

ia

OVERVIEW

LEARNING OBJECTIVES

1. Discuss the pathophysiology of MH.

2. Discuss triggering and non-triggering agents.

3. Describe the signs and symptoms to identify an MH crisis.

4. Discuss diagnosis and treatment of an MH crisis.

5. Discuss preventative measures required to provide safe care to patients who are

susceptible to MH.

The goal of this learning module is to review the key signs and symptoms of Malignant Hyperthermia (MH), to enhance early recognition, and to help each healthcare professional working in the operating room understand the role he or she may have to play in treating an MH episode.

This course is appropriate for everyone who has a role in healthcare: registered nurses, LPN/LVNs, and others. After completing this continuing education activity, the participant should be able to:

Malignant Hyperthermia

2 © 2014 Progressive Surgical Solutions, LLC

What is Malignant Hyperthermia (MH)

Malignant (extremely deadly) hyperthermia (very high temperatures) is a potentially lethal, acute, catastrophic, hypermetabolic syndrome involving the musculoskeletal system triggered in genetically predisposed individuals by commonly used general anesthetics.

• This syndrome may present in several ways and may occur at any point during or shortly after general anesthesia.

• It is best described as a syndrome, as not every patient will have the same response each time they are exposed to offending agents.

• Some patients may undergo multiple surgeries without incident and then experience a full-blown crisis during a subsequent procedure.

• It can recur in the postoperative period even after a positive response to initial treatment.

• The current mortality rate is less than 10%. • In susceptible individuals, MH can also occur in a milder form with exercise in heat

conditions.

Triggering and Non-Triggering Agents

• All volatile inhalation (gas) anesthetics are triggering agents.

• The most commonly used triggering inhalation anesthetics are: o Sevofluorane, Isofluorane, Desflurane and Halothane

• The only inhalation agent that doesn’t trigger an episode of

MH is Nitrous Oxide.

• Other non-triggering agents include: o Regional and local anesthetics o Benzodiazepines, opioids, non-depolarizing muscle relaxants, propofol,

barbituates, ketamine, catecholamines, alpha 2 agonists and etomidate.

• The other triggering agent is the depolarizing neuromuscular blocking agent Succinylcholine, AKA Anectine.

o Succinylcholine is the muscle relaxant of choice during endotracheal intubation

3



Signs and Symptoms

• Increasing End tidal CO2: The measurement of carbon dioxide during exhalation.

• Muscle Rigidity: Due to excess calcium release, muscle rigidity is likely to be present and may involve the trunk or total body. Masseter muscle rigidity (MMR) was noted to be an early sign of MH in the 1970s. As many as 1% of children induced with an inhalation agent and given succinylcholine may develop MMR. If generalized rigidity also occurs, then the diagnosis of MH is almost certain.

• Masseter Spasm or Trismus: Jaw muscle rigidity or the inability to open one’s mouth. When this tightness becomes prolonged, known as “jaws of steel” the risk that this patient is MH susceptible increases by 50%. This can occur even with pre-treatment. If limb rigidity occurs with Succinylcholine, begin treatment with Dantrolene.

• Increasing PaCO2: The circulating carbon dioxide increases as a result of the anaerobic metabolism and excess lactic acid production.

• Tachycardia: Increased heart rate as a result of excess spillage of potassium into the circulation.

• Tachypnea: Rapid respirations as a result of the central and peripheral chemical receptors that control respiration, are stimulated by the build up of excess circulating CO2 and lactic acid.

• Respiratory and Metabolic Acidosis: Excess CO2 and lactic acid in the circulation causing a drop in the pH.

• Arrhythmias: Due to the chemical derangement caused by excess potassium, acids, proteins and catecholamines released into the blood stream.

• Rising Temperature: The hallmark sign, fever is a late occurrence. With the increased energy production comes heat production. Mortality is related to the extremely high body temperature, upwards of 110°F. Coagulopathy and organ failure are a high consequence of a resulting high fever. ** Fever can be masked by a cold OR environment.

• Cyanosis: Skin turns blue due to above and decreased circulating O2 and increased circulating CO2.

• Hyperkalemia: High potassium (K) levels result from excess release from cells during the crisis.

End-stage organ damage occurs when the brain is deprived of oxygen, acid levels rise and when myoglobin clogs the renal tubules, causing renal failure. If the patient’s body temperature rises above 108 degrees F, changes occur in the coagulation pathway leading to disseminated intravascular coagulation (DIC). DIC is almost always fatal.

If an MH crisis is not identified early and/or is left untreated, these changes can cause cardiac arrest, renal failure, internal hemorrhage, brain injury, liver failure and may be fatal.



Diagnosis and Treatment

• When the signs have been recognized, and a definitive diagnosis of MH has been made, the first and most important action the anesthesiologist should do is to stop the inhalation agents and start hyperventilating with 100% oxygen to help blow off the excess CO2.

• Don’t waste time changing the circle (circuit) system and CO2 absorbent. • Call 911 as soon as a potential MH emergency is recognized

for patient transfer to the hospital. o MH 24-hour Hotline (for emergencies only) Ø United States: 1+800-644-9737 Ø Outside the US: 00+1+209-417-3722

• The surgeon should be informed of the patient’s crisis and encouraged to rapidly end the surgery.

• Get Help. Get Dantrolene. • The MH cart/supplies will be brought into the OR and lots of help will be needed! • Dantrolene comes in 20 mg vials that also contain 3 grams of mannitol (diuretic).

Reconstitution is accomplished with 60 mLs of preservative free “sterile water for injection.”

• FYI – This can be very difficult to do. One RN using a fluid dispensing system is reconstituting, one person is vigorously shaking it into solution, one RN is drawing it up, and one RN or an anesthesiologist is pushing it.

• Dantrolene dosage is 2.5 mg/kg IV bolus (approx 1mg/lb). Repeat as often as necessary titrated to control clinical signs. Sometimes more than 10 mg/kg (up to 30 mg/kg) is necessary. This may take 10 vials initially.

• Bicarbonate for metabolic acidosis. Dosage is 1-2 mEq/kg if blood gas values are not yet available.

• Cool the patient. Lavage open body cavities and/or apply ice to the surface areas, neck, axilla and groin.

• Infuse cold 0.9 % NaCl intravenously (do no use LR as it may contribute to the patient’s acidosis).

• Monitor temperature frequently. In using all these cooling measures you need to be careful there isn’t inadvertent hypothermia. (Use any means necessary to treat temperature, if it has risen or to prevent if from rising).

• Anti-arrhythmic therapy with beta-blocker, Esmolol 0.25 mg/kg IV or Lidocaine 1 mg/kg IV.

**Calcium channel blocking agents are often used in the treatment of arrhythmias. Giving these drugs along with Dantrolene may lead to marked and life-threatening hyperkalemia and myocardial depression.

5



Diagnosis and Treatment (continued)

• Insert foley catheter and an urimeter to measure urinary output. • Once the MH episode is controlled in the OR, the patient needs to be carefully

monitored for 36 hours. Dantrolene should be administered in a dose of 1-2 mg/kg every 4-6 hours titrated to signs of MH or if there are no signs, then the drug should be given empirically for at least 24 hours.

• Recurrence of an MH episode occurs in 25% of patients despite initial treatment of Dantrolene.

The MH Emergency Cart

911 should be called as soon as a potential MH emergency is recognized, for patient transfer to the hospital, but therapy at the surgery center should be aimed at prompt treatment of hyperkalemia, administration of Dantrolene, hyperventilation, and cooling to a target core temperature of 38°C. Every facility that administers general anesthesia or has MH triggering agents should be fully equipped to handle an MH emergency. ASCs typically don’t have the capacity of providing electrolyte testing and ABG testing or CVP insertion and monitoring, so those supplies are not necessary to keep in the facility. Facilities equipped to handle an MH emergency should perform a drill annually.

Drugs

1. Dantrolene – 36 vials should be available, each to be diluted at the time of use with 60 ml sterile water for injection USP (without a bacteriostatic agent).

2. Sterile water for injection USP (without a bacteriostatic agent) – Each vial of Dantrolene should be reconstituted by adding 60 ml of sterile water for injection USP (without a bacteriostatic agent) and the vial shaken until the solution is clear. If the MH episode is proceeding rapidly, simply mix and inject. It is mandatory to get Dantrolene to its effected site, the skeletal muscle. It is advised that the sterile water be stored in 100 ml vials, not bags, to avoid accidental IV administration of this hypotonic solution.



Drugs

3. Sodium bicarbonate (8.4%) – 50 ml x 5

4. Dextrose 50% – 50 ml vials x 2

5. Calcium chloride (10%) –10 ml vial x 2

6. Regular insulin – 100 units/ml x 1 (refrigerated)

7. Lidocaine* for injection (2%) – 100 mg/5 ml or 100 mg/10 ml in preloaded syringes (3). Amiodarone is also acceptable. ACLS protocols, as prescribed by the AHA, would be followed when treating all cardiac derangements caused by MH. • Lidocaine or procainamide should not be given if a wide-QRS complex arrhythmia is

likely due to hyperkalemia; this may result in asystole. 8. Refrigerated cold saline solution – A minimum of 3,000 ml for IV cooling

General Equipment

1. Syringes - (60 ml x 5) to dilute Dantrolene

2. Intravenous Catheters - 16G, 18G, 20G, 2-inch; 22G, 1-inch; 24G, 3/4-inch (4 each) (for IV access and arterial line)

3. NG Tubes - sizes appropriate for your patient population

4. Toomy Irrigation Syringes - (60 ml x 2) with adapter for NG irrigation

Monitoring Equipment

1. Esophageal or other core (e.g., nasopharyngeal, tympanic membrane, rectal, bladder, pulmonary artery catheter) temperature probes

2. CVP kits (sizes appropriate to your patient population)

3. Transducer kits for arterial and central venous cannulation

Nursing Equipment

1. Large sterile Steri-Drape (for rapid drape of wound)

2. Urine meter x 1

3. Irrigation tray with piston (60cc irrigation) syringe

4. Large clear plastic bags for ice x 4

5. Small plastic bags for ice x 4

6. Bucket for ice

7. Test strips for urine analysis

7



Prevention of MH

• Pre-op screening of personal/family history of anesthetic problems and neuromuscular disorders is done on every patient scheduled for surgery.

• The best way to prevent MH is through detection of those at risk prior to surgery. Patients with a family history of MH or suggestive of MH should ensure that this information is communicated to his/her anesthesia caregiver.

• Because MH is considered a dominantly inherited disorder, all members of a family in which MH has occurred must also be considered MH susceptible and managed accordingly, unless proven otherwise.

• It should be noted that those who have had previous anesthetics without problem cannot be certain they are not at risk.

Monitoring Tools

• Temperature/end-tidal CO2 monitoring during general anesthesia. • Recognition of masseter muscle rigidity. • Investigation of unexplained tachycardia, hypercarbia, hyperthermia. • Availability of Dantrolene and the Malignant Hyperthermia Cart. • Avoiding MH triggers in MH susceptible patients.

Conclusion

Report the episode on the AMRA form to the MH Registry of MHAUS. Forms are available by contacting: North American MH Registry of MHAUS

UPMC Mercy Hospital 8th Floor, Ermire Building (B)

Room 8522-3 1400 Locust Street

Pittsburgh PA 15219 1-888-274-7899

www.mhaus.org/registry

Alert the family to the dangers of MH in the other family members. Refer family members for testing at the nearest MH Diagnostic Testing Center.

Individuals who experienced MH episodes should have blood sent for genetic screen of RYR1. The successful management of MH requires that the providers:

• Know about it. • Be prepared for it. • Know what signs to look for. • Know their roles if and when it happens.

While MH is an uncommon entity, it can kill in minutes if not recognized and managed promptly. Bringing an episode to a successful conclusion depends on each and every member of the operating team!



References

• Malignant Hyperthermia Association of the United States www.maus.org

• Association of perioperative Registered Nurses www.aorn.org

• Advancing Knowledge in Healthcare www.akh.org

• Outpatient Surgery Magazine Feb 2012 Are You Ready for a Malignant Hyperthermia Emergency? www.outpatientsurgery.net/issues/2012/02/print&id=10116

• OR Nurse 2013 Taking the Heat Out of Malignant Hyperthermia www.ORNurseJournal.com


Log in to eSupport to take a post test.

Other CEU Learning Modules available on • OSHA Overview • Abuse Identification • Fluoroscopic Imaging in the OR • Hazard Communication • Radiation Safety • Infection Control 1 • Infection Control 2 • Latex Sensitivity • Steam Sterilization • TASS and Endophthalmitis • Workplace Violence • Disaster Preparedness • Sterilization Best Practices in the ASC

CONTACT US:

www.pss4asc.com

[email protected]

(855) PSS – 4ASC (855) 777 – 4272

Documents

OVERVIEW LEARNING OBJECTIVES