Nurs614 Exam 2 Malignant Hyperthermia

Front 1

What is Malignant Hyperthermia?

Back 1

MH is primarily an autosomal dominant inherited disorder of skeletal muscle (mutation in ryanodine receptor). This means that children, parents and siblings of an MH susceptible have a 50% chance of inheriting MH susceptibility.

Front 2

What triggers MH in susceptible humans and animals?

Back 2

Inhalation agents, succinylcholine, and in rare cases exercise.

Front 3

MH is characterized by:

Back 3

Hypermetabolism
Hypercarbia and hypoxemia
Skeletal muscle damage
Hyperthermia (late sign)
Death (if left untreated)

Front 4

What is the mortality associated with MH?

Back 4

5% to 10% secondary after the advent of Dantrolene

Front 5

Incidence of MH:

Back 5

1:45,000 to 1:60,000
Children: 1:15,000
Adults: 1:50,000

Front 6

Demographics of MH:

Back 6

Increased incidence in Wisconsin, Nebraska, West Virginia, and Michigan; Increasing in the Carolinas;
Among all ethnic groups;
Males more than females

Front 7

What is the pathophysiology of MH?

Back 7

Inherited defect in the Ryanodine receptor.
Ryanodine receptors are proteins located on the SR and are designed for fast release of Ca.
It leads to loss of cellular Ca control secondary to mutations.

Front 8

Explain what happens when an MH susceptible person is exposed to triggering anesthetics?

Back 8

Exposure to triggering anesthetics results in high levels of Calcium in the myoplasm and persistent skeletal muscle contraction resulting in rigidity --> hypermetabolism

Front 9

Where in the cell does calcium come from (to generate a muscle contraction)?

Back 9

Calcium comes from: sarcoplasmic reticulum, influx from sarcolemma and release from mitochondria.

Front 10

Explain the reason for elevated temps associated with MH?

Back 10

Heat generation is secondary to the Calcium pumps attempting to restore homeostasis which results in large ATP utilization and increased aerobic and anaerobic metabolism and hypermetabolic state --> elevated temp.

Front 11

In MH, how is ETCO2 affected?

Back 11

ETCO2 may increase 2-3 x greater

Front 12

In MH, how is the HR affected?

Back 12

There may be unexplained tachycardia (this is also one of the signs)

Front 13

List 9 inhalation agents or drugs that are MH Triggering agents?

Back 13

Isoflurane
Desflurane
Enflurane
Sevoflurane
Halothane
Diethyl ether
Cyclopropane
Methoxyflurane
Succinylcholine

Front 14

With the current concepts regarding MH and with the use of the newer inhalational anesthetics, what is the earliest sign of MH?

Back 14

End-tidal CO2 elevation is usually the earliest sign

Front 15

With the current concepts regarding MH and with the use of the newer inhalational anesthetics, muscle rigidity may/may not be present. If present, is it an early or late sign?

Back 15

Early

Front 16

With the current concepts regarding MH and with the use of the newer inhalational anesthetics,is elevated temp an early or late sign?

Back 16

Elevated temperature is a late sign.

Front 17

With the current concepts regarding MH and with the use of the newer inhalational anesthetics,when is MH most likely to appear?

Back 17

MH may occur at any point during anesthesia or on emergence (or even in the PACU).

Front 18

With the current concepts regarding MH and with the use of the newer inhalational anesthetics,what if any, are the changes in mortality?

Back 18

It is low (<10%).

Front 19

In the evolution of the understanding of MH, what were the original concepts held?

Back 19

That most patients have muscle rigidity;
That there was fast onset of elevated core temperature & acidosis;
High mortality prior to Dantrolene and ETCO2 (>80%).

Front 20

How fast does ETCO2 rise in MH?

Back 20

It may increase over minutes or hours

Front 21

If you find yourself making upward adjustments on your tidal volumes and RR to maintain a normal ETCO2,you should?

Back 21

CONSIDERED MH!!

Front 22

List 12 S/S of MH :

Back 22

Rhabdomyolysis;
Tachycardia with or without dysrhythmia;
Tachypnea (if un-paralyzed);
Increased ETCO2
Increased acidosis - metabolic and respiratory secondary to the increases in CO2 production;
Increased creatinine
phosphokinase (CPK);
Hypercalcemia;
Hyperphosphotemia;
Myoglobin in urine (makes urine dark brown);
Increased serum K+,
Increased lactate (anaerobic metabolism);
Increased temperature;

Front 23

Symptoms can occur over 4 hours or longer. True/false

Back 23

True

Front 24

What test is used to diagnose MH?

Back 24

The Caffeine/Halothane Contracture Test (CHCT)

Front 25

When was the Caffeine/Halothane Contracture Test developed?

Back 25

This muscle contracture test was developed in the 1970s.

Front 26

What does the Caffeine/Halothane Contracture Test rely on?

Back 26

It relies on exposing MH skeletal muscle (latissimus) to halothane and caffeine to detect an abnormally elevated contracture linked to calcium release.

Front 27

Why is the Caffeine/Halothane Contracture Test considered invasive?

Back 27

It requires an open skeletal muscle biopsy obtained with surgery and anesthesia.

Front 28

Where is the Caffeine/Halothane Contracture Test done?

Back 28

These bioassay test is done on the muscle in vitro in MH centers.

Front 29

How much does the Caffeine/Halothane Contracture Test cost and is it covered by insurance?

Back 29

It is expensive ($5-6,000) and is usually covered by insurance.

Front 30

What must the suspected MH individual do to get tested?

Back 30

Must travel to one of the six MH diagnostic centers in the US. There is one in Bethesda , MD

Front 31

In the treatment (tx) of MH, what is the first thing to do?

Back 31

Discontinue offending agents
(For eg, turn off for gas)

Front 32

In the treatment of MH, why do we ventilate with 100% oxygen?

Back 32

To minimize the effects of:
Hypercapnia;
Metabolic acidosis;
Increased O2 consumption

Front 33

In the treatment of MH, how do we tx hyperkalemia?

Back 33

With insulin and glucose

Front 34

When treating MH, what is the rationale for diuresis?

Back 34

To prevent ARF from myoglobinuria

Front 35

In the treatment of MH, how do we tx acidosis?

Back 35

Give bicarbonate 1-2 mg/kg PRN

Front 36

What medication is used to tx MH?

Back 36

Dantrolene 2.5mg/kg IV. Repeat same dose PRN
Titrate up to 8-10mg/kg. Even if ineffective, keep giving till effect.
After cessation of s/s, give Dantrolene 1mg/kg every 4-6 hours for 24 - 36 hours.

Front 37

How do we tx hyperthermia in MH?

Back 37

Cool patient - gastric lavage using sterile water(and also lavage any other body cavity that is feasible)
surface cooling including wounds,
ice packs over major arteries,
cool air convection,
cooling blankets.
Cold dialysis & CP bypass if other measures fail.

Front 38

When treating arrhythmias in MH, what is absolutely contraindicated?

Back 38

Calcium channel blockers -they promotes hyperkalemia

Front 39

When treating MH, what lab values should be monitored?

Back 39

Arterial and/or venous blood gases – get an aline;
electrolytes and coagulation studies

Front 40

How is dantolene packaged?

Back 40

It comes 20 mg per vial to be reconstituted in 60 ml sterile water

Front 41

During the post acute phase of an MH episode, what is the minimum recommended amt of time the pt should spend in the ICU?

Back 41

Observe patient in ICU for 24 hours following MH episode.

Front 42

What responsibility does the anesthesia provider have to the family of the newly identified MH pt?

Back 42

To counsel the patient and family to get tested. There is a possibility that other people in the family may have MH.

Front 43

After an MH episode, a report must be made to a registry. What is the name of the report and the registry?

Back 43

Complete Adverse Metabolic Reaction Report.
The North American MH Registry.

Front 44

If pt has a h/o MH, is it necessary to premedicate with dantrolene?

Back 44

No

Front 45

For the MH Susceptible patients how should you prepare the equipment (ventilator/tubing/anesthesia machine/vaporizer, etc)?

Back 45

Shut down and/or disable vaporizers - label vaporizer with “MH”
Flow oxygen at 10 L/min for 20 minutes through machine and ventilator;
Allow the air to blow out from Y-piece;
Change carbon dioxide absorbent.

Front 46

What is masseter rigidity (tightness in jaw) an indication of?

Back 46

MH. Although not totally correlated, it is a good indicator of presence of MH.
If present, cancel elective surgery.

Front 47

What does the AANA MH Preparedness Statement say?

Back 47

Anesthesia departments/providers should be prepared to treat MH;
OR/PACU personnel should be trained in the recognition and treatment of MH;
MH cart should be available in anesthetizing and recovery areas;
A written treatment plan should along with the 24-hour MHAUS Hotline number shoould be posted with cart.