MH

Question 1

Geology more likely states:

Answer 1

Wisconsin
nebraska
west virginia
michigan

Question 1

Incidence of MH:

Answer 1

1 in 100,000 Sx procedures in adults and 1 in 30,000 in children

52% all reactions are documented in children <15 yrs age

Higher in males

Question 1

Pathophys of MH

Answer 1

Inherited disorder of skeletal muscle

DEFECT in calcium regulation that is expressed by exposure to specific anesthetic triggers (VA or Succ)

Question 2

Most genetic variants are found on:

Answer 2

RYR1 gene (70% of cases)
- codes the ryanodine receptor
-major calcium release channel of the sarcoplasmic reticulum

Question 3

VA or Succ include MH which cases the following:

Answer 3

Enhanced calcium release from SR - effects skeletal muscle

ELEVATED Calcium results in muscel contraction and abnormal muscle metabolism - attempted removal of calcium increases metabolism

OXYGEN consumption, CO2 production, heat production, LA production

ATP depelted

ACIDOSIS, hyperthermia, ATP depletion cause the sarcolemma to be destroyed which increases K, myoglobin and CK

Question 4

Clinical manifestations of MH:

Answer 4

TYPICALLY occurs immediately after induction of anesthesia, but can occur several hours into the sx or even when the surgery is completed

Question 5

Succ may increase the risk of MH:

Answer 5

20x and hasten the onset and severity of the episode

Question 6

Clinical events that occur with MH

Answer 6

Unexplained sudden RISE in ETCO2 >55mmHg most RELIABLE sign - RISES out of proporotion to minute ventilation

Unexplained tachycardia

Masseter muscle rigidity - cant open jaw

RISING temp 1-2 C every 5 mins at an average temp of 39.3

COLA colored urine (myoglobinuria)

Decreased SaO2
Labile BP
mottled,cyanotic skin

Question 7

Clinical labs with MH;

Answer 7

ABG - mixed resp/metabolic acidosis

SERUM K >6
CK > 20,000
Serum Myoglobin - 170mcg/L
Urine myoglobin - >60mcg/L

Blood lactate levels 10-20x

Question 8

Question 9

On average, how many anesthetics occur before a triggering event:

Answer 9

3

Question 10

Qutesions to ask in preop

Answer 10

Any family history of unexpected intraoperative complications or deaths
Any family history of MH, muscle rigidity/stiffness, and/or high fever under anesthesia
Personal history of dark/cola colored urine after surgery/exercise
Personal or family history of high temperature or death during exercise

Question 11

All fam hx must be:

Answer 11

Treated as MH positive

Question 12

Diseases that show a genetic link to MH susceptibility:

Answer 12

Central core disease
King-Denborough syndrome
Multi-minicore myopathy

Question 13

Managmenet of MH

Answer 13

1. Call for help and alert the surgeon to conclude the procedure promptly
2. Immediately discontinue the volatile anesthetic and succinylcholine
   - If surgery must be continued, maintain general anesthesia with intravenous non-triggering anesthetics
   3/ Prepare and administer 2.5mg/kg dantrolene intravenous bolus and repeat as necessary every 5-10 minutes until symptoms diminish (administer through largest IV possible)
   - Sometimes will need 10mg/kg dose
3. Hyperventilate with 100% O2 at high flows (at least 10L/min)
4. If available, apply charcoal filters to each limb of the anesthesia circuit and replace after 1 hour of use
5. If fever is present (>39 C) or if temp is rapidly rising, initiate cooling by lavage, administration of chilled IV normal saline, and surface cooling
6. Treat arrhythmias with standard antiarrhythmic agents. NO calcium channel blockers
7. Check ABG, serum electrolytes, blood glucose
   - Consider administration of sodium bicarbonate for pH < 7.2
8. Treat hyperK
9. maintain UO > 1ml/kg/hr
10. Continue to monitor

Question 14

Hyperventialtion provides several benefits:

Answer 14

facilitates CO2 elimination

Enhances O2 delivery

Drives K into cells

Question 15

Treating HyperK

Answer 15

Hyperventilation

Calcium chloride 10mg/kg (max dose 2000mg) or calcium gluconate 30mg/kg (max dose 3000mg)

Soidum bicarb 1-2mEq/kg IV

Glucose/insulin admin 10 units regulat insulin +50mL 50% dextrose

Question 16

Who can you call?

Answer 16

Malignant Hyperthermia Association of the United States (MHAUS) early to report the MH event; they will also walk you through steps on what to do
1-800-644-9737

Question 17

Dantrolene packaged:

Answer 17

As 20mg vials that must be reconstituted with 60ml of sterile water for injection

EACH vial of dantrolene contains 3g of mannitol

Question 18

MOA of dantrolene:

Answer 18

Muscle relaxant

WILL REDUCE Ca release from RYR1 receptor

WILL PREVENT Ca entry into the myocyte (REduces stimulus for calcium induced calcium release)

Requires vigorous mixing and therefore you will need multiple people to be preparing it at once so you can maintain the administration

Question 19

Ryanodex is packaged as:

Answer 19

250mg vials and requires 5ml of sterile water diluent

EACH vial of ryanodex contains 0.125g of mannitol

Question 20

If sx permits, what is preferable for MH patient:

Answer 20

REGIONAL or LOCAL

Amides and esters are non triggering

Question 21

What should be readily available with MH:

Answer 21

MH kit/cart in OR

Ice and 3000mL of cold IV fluid

Question 22

Trace anesthesia gas from anesthesia machine must be removed via the following:

Answer 22

Change out CO2 ABSORBER

REMOVE anesthetic vaporizers

FLUSH the anesthesia gas machine via 10L/min for 20-30 minutes

Attach new circuit and reservoir bag

ATTACH activated charcoal filters on insp and exp limbs of circuit

Question 23

What do activated charcoal filters do?

Answer 23

Remove anesthetic gasses and the need for purging the system STILL NEED to flush teh gas machine for 90 secons @ 10L/min prior to placing the filters WILL KEEP anesthetic agent concentration below 5ppm for up to 12 hours with FGF of at least 3L/min

Question 24

What is the most accurate test for determining MH?

Answer 24

CAFFEINE halothane contracture test (CHCT) takes biopsy of skeletal muscle from patient and measures its contractile response to caffeine, halothane, or both

Question 25

What would normal muscle do with CHCT?

Answer 25

RESPOND to caffeine or halothane, but is augmented in the patient with MH

Question 26

MHAUS recommends the CHCT test for the following:

Answer 26

Patient with an MH positive family member Patient with a past suspected MH event Patient with severe masseter muscle rigidity during anesthesia Patient with moderate to mild masseter muscle rigidity Patient with unexplained rhabdomyolysis during or after surgery Patient with exercise induced rhabdomyolysis after negative rhabdomyolysis workup

Question 27

Postop care after MH episode:

Answer 27

MONITORED in the ICU for MH complications IV dantrolene continued 24 hours at 1mg/kg every 4-6 hours or 0.25mg/kg/hr by continuous infusion

Question 28

Dantrolene can be stopped or the intervels between can be increased if the followign occurs

Answer 28

Metabolic stability for 24 hours Core temp < 38C CK is decreasing No evidence of myoglobinuria Muscle rigidity has resolved

Question 29

S/S of serotonin syndrome:

Answer 29

Mental status changes: anxiety, agitation, confusion Autonomic instability Hyperthermia, tachycardia, tachypnea, diarrhea, abdominal pain Neuromuscular hyperactivity: Clonus, tremor, rigidity Signs and symptoms can appear within minutes or up to 24 hours after initial use of medication, change in dose or addition of new serotonergic drug

Question 30

Tx of serotonin syndrome

Answer 30

CESSATION Benzos for agitation and tremor CYPROHEPATIDINE (H1 receptor antagonist) - 12mg orally - additional 2 mg given every 2 hours until s/s imporove or max dose of 32mg has been reached

Question 31

Answer 31

Question 32

What are pheochromocytomas?

Answer 32

are catecholamine-secreting tumors derived from chromaffin cells in the adrenal medulla

Question 33

Pheo incidence

Answer 33

0.6 cases per 100,000 people 40% of patients who have a pheochromocytoma have an inherited syndrome (neurofibromatosis 1, von Hippel-Lindau syndrome, MEN-2a and MEN-2B Equally likely in men and women, but more likely to occur in 3rd, 4th, and 5th decades of life

Question 34

How are Pheos found?

Answer 34

BY ELEVATED CATS and fractioned METANEPHRINE levels in the blood and urine followed by confirmation by CT or MRI

Question 35

where are pheo tumors found mostly?

Answer 35

85% in adrenal glands

Question 36

What do pheos secrete?

Answer 36

Norepi and epi PRIMARY norepi

Question 37

Rule of 10s with pheo:

Answer 37

involve both adrenal glands in 10% of patients 10% are extra adrenal (paraganlgiomas) 10% are malignant

Question 38

S/S of pheo

Answer 38

Diaphoresis Tachycardia Headache Hypertension Anxiety Pallor Increased metabolism typical spell is less than an hour but can be variable and can be triggered by abdominal pressure, exercise, sx, change in posture or lifting

Question 39

Vasoconstriction from norepi secretion may cause:

Answer 39

PAIN PARESTHESIA CLAUDICATION ISCHEMIA can lead to HF, pulm edema, arrhythmias, and intracranial hemorrhage

Question 40

Tx of pheo:

Answer 40

SURGICAL RESECTION COmplications during sx are intraoperative HTN, BP lability and POSTresection hypotension Since patients have had catecholamines released for as long as they’ve had the pheochromocytoma it is important to assess for dilated cardiomyopathy, heart failure, and diastolic/systolic dysfunction

Question 41

Anesthetic considerations with Pheo:

Answer 41

Preop tx of HTN and expansion of fluid compartments before sx ALPHA ADRENERGIC BLOCKADE (FIrst line tx) - Phenoxybenzamine (nonselective) - Dose 10-30mg oral - Duration 24-48 hours Doxazosin/Terazosin (selective) BETA ADRENERGIC BLOCKADE Large bore IV's arterial line required Expect HTN during induction, when tumor is surgically manipulated Expect hypotension after

Question 42

What to avoid with pheos

Answer 42

Avoid dopamine antagonists (metoclopramide, droperidol), histamine-producing agents (morphine), indirect amines (ephedrine)

Question 43

Alpha and beta with pheo:

Answer 43

Alpha blockade ALWAYS before Beta blockade Blocking beta receptors prior to alpha receptors can cause severe hypertension due to unopposed alpha-mediated vasoconstriction

Question 44

What is important with induction and pheo

Answer 44

SLOW AND CONTROLLED induction to maintain cardiac stability but increase anesthetic depth Avoid des (Tachy) Ketamine (SNS) Succ (Mechanical compression of tumor during fasciculations)

Question 45

Tx hypertension with pheo in the OR with:

Answer 45

Phentolamine Non-Selective Alpha Blocker 1mg test dose, then 1-5mg bolus every 5 min Infusion 0.5 – 1 mg/min as needed Clevidipine Nitroglycerine Nicardipine Treat dysrhythmias with esmolol (rapid/short acting)

Question 46

What is a thyroid storm

Answer 46

A SEVERE EXACERBATION of hyperthyroidism in the previously undiagnosed or incompletely treated hyperthyroid patient that can occur due to trauma, surgery, peripartum, acute illness and infection Mortality rates 20-30%

Question 47

When does thyroid storm occur?

Answer 47

6-18 hours after sx

Question 48

Clinical manifestations of thyroid storm:

Answer 48

Alterations in consciousness Tachycardia Hyperpyrexia > 38.5 C Hypertension Arrhythmias Metabolic acidosis – due to lactate production from increased metabolism Tremor

Question 49

Tx of thyroid storm

Answer 49

Identifying and treating precipitating cause Administering antithyroid medications (stops synthesis of thyroid hormones) Propylthiouracil (PTU) – 200-400 mg orally or via NG tube Radioactive iodine, potassium iodide (blocks release) Propranolol, glucocorticoids (blocks T4 to T3 conversion) Titrated B-adrenergic receptor blockers Esmolol (fast acting) Labetalol Metoprolol Hydration with glucose containing crystalloid solutions Correction of electrolyte and acid base imbalances Management of hyperthermia Acetaminophen (salicylate) Salicylates may displace T3 and T4 from carrier proteins