Malignant Hyperthermia Flashcards by hassan gonzales

MH is transmitted by

Autosomal Dominance

How well did you know this?

Not at all

Perfectly

Where is the genetic defect located chromosomally

Long arm of chromosome 19

How well did you know this?

Not at all

Perfectly

Where is the defect associated with MH

Ryanodine receptors

Ry1 (skeletal) only

How well did you know this?

Not at all

Perfectly

True/False

Triggering of MH may not occur with a SINGLE anesthetic exposure

True- may trigger after several exposures

How well did you know this?

Not at all

Perfectly

True/False

MH is a malignancy

False

How well did you know this?

Not at all

Perfectly

True/False

MH causes hyperthermia

False

How well did you know this?

Not at all

Perfectly

What is MH

A fulminant HYPERMETABOLIC state of skeletal muscle induced by VOLATILE inhalational anesthetics, succinylcholine, and perhaps by stress/excercise

How well did you know this?

Not at all

Perfectly

** What is the MOA of MH

Release of substantial amounts of calcium into sarcoplasm caused by defective Ryd1 receptors, with reversal of usual gradients into the SR, mitochondria, and/or sarcolemma into extracellular fluid.

As a result, calcium pump requires excessive amounts of ATP leading to heat, acid, and C02 production which alters the energy supply and demand and causes cell breakdown, release of intracellular contents, and ischemia

How well did you know this?

Not at all

Perfectly

How does Dantrolene stop MH

by stopping the loss of calcium from SR, but not interfering with calcium uptake. This allows the calcium pumps to catch-up with calcium demands

How well did you know this?

Not at all

Perfectly

Name the triggering agents for MH

All halogenated agents including: Methoxyflurane, Cyclopropane, ether, and the rest

Succinylcholine
Decamethonium

How well did you know this?

Not at all

Perfectly

List the Main clinical presentations of MH

SNS stimulation secondary to hypermetabolism
TACHYCARDIA
MASSETER MUSCLE RIGIDITY and generalized muscle rigidity 
HYPERCAPNIA
INCREASED TEMP (1-2 degrees/5 min)
hyperKalemia
hyperCacemia
myoglobinuria
CPK > 20K 
Lactidemia r/t hypermetabolism
Ventricular dysrhythmias

How well did you know this?

Not at all

Perfectly

MMR occurs more commonly in

children

young adults

How well did you know this?

Not at all

Perfectly

Most MMR occurs after which inhalation/muscle blockers

Halothane, Sevoflurane following succs administration

How well did you know this?

Not at all

Perfectly

Will repeat doses of succs or NDMR relieve MMR

How well did you know this?

Not at all

Perfectly

What will the peripheral nerve stimulator reveal with MMR

flaccid paralysis

How well did you know this?

Not at all

Perfectly

List the differential diagnosis for MMR

Myotonic syndrome
TMJ dysfunction
Underdosing with succs
Not allow succs to work
Increased resting tone after succ with fever or elevated epi levels

How well did you know this?

Not at all

Perfectly

List management strategies with MMR

DC anesthesia and postpone case if possible
continue anesthesia with non-triggering agent
give dantrolene, only if generalized rigidity/hypermetabolism noted
admit for 12-24 hours after episode
serial CKs, at 6,12,24 hours
* contracture test- only definitive diagnosis

How well did you know this?

Not at all

Perfectly

Identify other dx’s associated with MH

King-denborough syndrome
Duchenne muscular dystrophy
Becker dystrophy
Myopathies
Myotonias
Periodic paralysis
Osteogenesis imperfecta

How well did you know this?

Not at all

Perfectly

List syndromes with clinical resemblances to MH

Pheochromocytoma
Thyrotoxicosis
Sepis
Hypoxic encephalopathy
Mitochondrial myopathies
NMS
Serotonin Syndrome

How well did you know this?

Not at all

Perfectly

Differences between pheochromocytoma and MH

Highest BP/ Tachy with pheo
No rigidity with pheo
CO2 less with pheo

How well did you know this?

Not at all

Perfectly

Differences between Thyrotoxicosis and MH

Study These Flashcards

Second highest BP ever seen/Tachy

CO2 less with thyrotox

Hypoxic encephalopathy and MH

Study These Flashcards

Patient doesnt wake up, posturing, stiff neck with HE

NMS and MH

Study These Flashcards

In NMS, symptoms occur in severly ill patients treated with antipyschotics, or dopamine antagonists with symptoms resembling MH such as: muscle rigidity, and hyperpyrexia

NMS:

Severe muscle rigidity
Slow onset (1-3 days)

Treatment of NMS include

Study These Flashcards

temperature, acid-base, fluid status

Benzo, Bromocriptine (dopamine agonist), Dantrolene

Serotonin Syndrome

Occurs within hours vs. MH which occurs within minutes, Hypercapnia within minutes

Differential Diagnosis r/t ETCO2 > 5mmHg above steady state

**Increased CO2 production is most sensitive and specific for MH r/o fever, light anesthesia Decreased ventilation- r/o spont. breathing, ventilator issues, breathing circuit, pulmonary issues, extrathoracic issues Monitoring error-r/o technical problems

Differential Diagnosis r/t Tachycardia and Fever

Too much covers or ambient temp equipment problems Increased heat production-r/o infection,pheo, etc CNS-r/o hypothalamus injury, serotonin, prostaglandin Drug reactions-r/o NMS, MAOI, cocaine, TCA,ketamine, etc.

List treatment measures for MH

``` STOP triggering agent-start propofol infusion Hyperventilate with 100% oxygen Administer Dantrolene Initiate cooling measures Correct dysrhythmias Correct hyperKalemia Secure monitoring lines Maintain urine output Follow postop Call MHAUS ```

Dantrolene administration

IV STAT- 2.5 mg/kg with repeated doses until MH reversed. Dose can be as high as 10mg/kg, but should be less than 30 mg/kg

Metabolic acidosis correction

Correct metabolic acidosis with Sodium Bicarbonate per ABGs (1-2 mEq/kg)

Cooling measures

IV iced SALINE SOLUTION with 15 cc/kg/10 minutes for 30 minutes Surface cooling with ice, hypothermia blanket Lavage: stomach, bladder, rectum, peritoneal, thoracic cavities with NS *Stop cooling when temp < or equal to 38 C

Dysrhythmias correction

Correct hyperKalemia and acidosis | Don't give CCB- will cause hyperKalemia or cardiac arrest in presence of dantrolene

HyperKalemia correction

``` Hyperventilation Bicarbonate Glucose/Insulin- 10 Units with D50 50 mL Check glucose levels hourly Frequent ABGs ```

Monitoring lines

CORE temp Foley catheter art-line

Urine output

at least 2cc/kg/hr | give mannitol 1.25 gm/kg IV and Lasix 1 mg/kg up to 4 doses

Post incident monitoring and therapy

until episodes subsides put in ICU at least 24 hours PO dantrolene 1 mg/kg q 4-6 hours or 0.25 mg/kg/hr IV *titrate to muscle rigidity, tachycardia, and acidosis

For MH susceptible patients

``` Choose regional anesthetic prep anesthesia machine-remove vaporizers, change CO2 absorbent, 02 flow in circuit for 20 min at 10LPM Get preop CBC/CPK Cooling Blankets on OR table art-line/CVP ``` *Preop admin of dantrolene not recommended

Dantrolene is classified as a

skeletal muscle relaxant

Dantrolene works by

inhibiting the release of calcium from SR

Dantrolene is caustic to

tissues- prevent extravasation

Caution patients of -----, ----, ---- after dantrolene administration

decreased muscle strength (ambulation), light headness, and swallowing difficulties

What two drugs displace Dantrolene from plasma proteins, and thus increases risk for toxicity

Warfarin | Clofibrate

What drug increases plasma binding of Dantrolene, and thus decreases bioavailability

Tolbutamide

List the AE of dantrolene

Pulmonary edema r/t mannitol Thrombophlebitis r/t extravasation Urticaria/Erythema Hepatitis, seizure, pleural effusion, pericarditis with long term exposure

How is dantrolend prepared

dilute each vial with 60 cc Sterile water without BACTERIOSTATIC agent gently shake until clear Each vial contains 20 mg Dantrolene, 3 g Mannitol, and Sodium hydroxide pH is 9.5 Once mixed, must be used within 6 hours

what is a contracture test

A muscle biopsy is carried out at an approved research center, under local anesthesia. The fresh biopsy is bathed in solutions containing caffeine or halothane and observed for contraction; under good conditions

what is the sensitivity for the contracture test

100%- identifies those with dx

what is the specificity for the contracture test

78%- identifies who doesn't have dx

List the four basis for litigation r/t MH

failure to obtain a thorough personal hx failure to monitor temperature failure to have adequae supplies of dantrolene failure to investigate increase in temp, skeletal muscle tone when assoc. with incr. HR and dysrhythmias

What should you ask every patient preop r/t MH

"Have you or any family members ever had problems with anesthesia such as fever, or death"

Malignant Hyperthermia Flashcards

(50 cards)