MH and dantroline Flashcards Preview

In a liquid the particles have a range of energies. At the surface of the liquid some particles will have enough energy to escape from the liquid and overcome the attraction of the other liquid particles. This leaves the less energetic particles still in the liquid and so the liquid is cooler.

H2O is transferred from the surface to the atmosphere, the process by which water changes from a liquid to a gas

Through evaporation

Is the movement of thermal energy through a material without the particles in the material moving.

Transfer of energy through matter from particle to particle

Ryanodine receptor 1 (RYR-1) - on chromosome 19

CACNA1S gene - provides instructions for making calcium channels - on chromosome 1

STAC3 gene - protein encoded by this gene is a component of the excitation-contraction coupling machinery of muscles- on chromosome 12

1. membrane depolarization
2. Ca⁺⁺ release
3.  failure of negative feedback (that would otherwise decrease subsequant Ca⁺⁺ release) 
4. increased myoplasmic Ca⁺⁺ release 
5. hypoxemia and cell death and other events

Lots of ATP needed and used up for Ca++ release, reuptake into SR, and troponin “decoupling” (hypermetabolism)

Aerobic metabolism replaces ATP with heat and CO2 → lactic acidosis

Excess Ca⁺⁺​ also signals cell death

Myoglobin released causes rhabdo, hyperkalemia

When ATP is depleted = CV collapse

uncontrolled myoplasmic Ca⁺⁺ release

succinylcholine acts indirectly by activating the nicotinergic acetylcholine receptor (nAChR), a nonspecific cation channel, resulting in continuous local depolarization

The depolarization can trigger propagated action potentials and will further activate the dihydropyridine receptors (DHPR, CaV1.1)

this leads to the gating of both Ca⁺⁺ release from the SR via RyR1 and L-type Ca⁺⁺ current from the extracellular space

inhalational agents dirrectly on RYR1

they stimulate Ca⁺⁺ release via RYR1

Fluids and Mannitol - kidney protection

Oxygen

PPV & hyperventialtion - to remove CO₂

Bicarb (HCO₃) - for acidosis

Insulin & Glucose, Calcium - hyperkalemia 

Ice packs

AVOID Ca⁺⁺ channel blockers in dysrhythmias

Neuroleptic Malignant Syndrome

Light Anesthesia

Pain

Thyroid storm (Hyperthyroid)

Pheochromocytoma (esp if doing a bowel resection)

occult myopathy

May be early sign usually can still open the mouth for airway instrumentation

Stiff jaw but still can open –need to get airway secured incase something happens

Don't cancel the case, but be extra vigilent 

sustained contracture of the jaw muscles following succinylcholine disallowing mouth opening → may be a forewarning of MH

• A mild ↑ in masseter muscle tone following succinylcholine with limb flaccidity may be a normal response
• Immediately check K⁺ & ABG
• Clinical signs of MH occur in about 20% of cases of MMR

Not possible to determine, clinically, whether that ↑ in tone represents an MH reaction or not

If generalized rigidity also occurs → then MH is highly likely

↑ >20,000

During episode - Very high, up to 100,000

May be elevated up to 2 weeks after the event

Elevation correlates

• Best with rhabdomyolysis
• Less well with fever & acidosis

Rapidly developing rhabdomyolysis includes rapid ↑ in  K+ → leading to dysrhythmias

Slowly developing rhabdomyolysis is safer → K+ is redistributed before blood levels can ↑

Myoglobin "leaked" from damaged cells → urine

may occur within a few hours

should be anticipated & treated to prevent acute tubular necrosis

• Mannitol, diuresis, & ↑ fluids

High lactate & acidosis with very low pH

• may be

Cardiac contractility falls at low pH

• the response to NE and epi are GREATLY reduced

Heat loss

• Sweating
• Cutaneous vasodilatation

Sympathetic hyperactivity:

• ↑ circulating catecholamines
• ↑ HR, ↑ SVR, ↑ CO
• Cutaneous vasoconstriction

↑ ventilation

• as the CO₂ increases,  minute ventilation goes up
• may be masked by fentanyl 

postsynaptic muscle relaxant

antagonizes ryanodine receptors

inhibits Ca2+ ions release from sarcoplasmic reticulum → depresses excitation-contraction coupling in skeletal muscle

36 vials (720 mg) sufficient for a 70-kg person

each vial = 20 mg

Needed if succinylcholine is available for resuscitation even if it's a facility in which volatile anesthetics are not used

E½t 10-15h

Redosing Q 6hrs 

Dantrolene does not significantly potentiate effects of nondepolarizing relaxants or interfere with reversal of muscle relaxants

May cause significant muscle weakness in patients with pre-existing muscle disease (MS, MD ect.)

• still give with extreme caution

Sterile water (without bacteriostatic agent) 

1. Dantrolene 36 vials
2. Sterile water to reconstitute dantrolene: 1,000 ml x 2
3. Sodium bicarbonate (8.4%): 50 ml x 5
4. Furosemide: 40 mg/amp x 4 ampules
5. D₅₀: 50 ml vials x 2
6. CaCl (10%): 20 ml vial x 2
7. Regular insulin: 100 units/ml x 1  (refrigerated)
8. Lidocaine HCl (2%): 1 box = 2 grams or 10 ml/100 mg preloaded vial

1. Syringes (60 ml x 5) to dilute dantrolene
2. Mini-spike® IV additive pins x 2 & Multi-Ad fluid transfer sets x 2 (to reconstitute dantrolene)
3. Angiocaths: (4 ea.) (for IV access and arterial line – need to start an artline and more IVs)
4. 20G, 2-inch; 22G, 1-inch; 24G, ¾-inch
5. D5W 250 ml x 1 
6. Micro Drip IV set x 1
7. NG tubes (Size appropriate for patient population)
8. Irrigation tray with piston syringe (x1) for NG irrigation
9. Toomey irrigation syringes (60 ml x 2) for NG irrigation

1. Esophageal or other core temperature probes
2. CVP kits: size appropriate to patient population
3. Transducer kits for arterial & central venous cannulation

1. Large sterile Steri-Drape (for rapid drape of wound) – you may need to start CPR
2. Three-way irrigating foley catheters → size appropriate for patient population
3. Urine meter x 1
4. Irrigation tray with piston syringe
5. Rectal tubes [Sizes (Malecot Drain) 14F, 16F, 32F, 34F]
6. Large clear plastic bags for ice x 4
7. Small plastic bags for ice x 4
8. Bucket for ice

1. Ensure anesthetic vaporizers disabled by removing them from the machine
2. Change CO2 absorbent (soda lime/baralyme)
3. Flow 10 L/m O2 though circuit via ventilator for the amount of time specified by machine manufacturer (20-100 minutes)
4. During this time a disposable unused breathing bag should be attached to the Y-piece of the circle system & the ventilator set to inflate the bag periodically
5. Use new or disposable breathing circuit

Prophylaxis treatment is not recommended

may be discharged on the day of surgery

Minimum of 4 hours observation is strongly suggested

rocuronium

positive pressure

propofol

Therapy should be directed at treatment of hyperkalemia:

• Calcium chloride
• Bicarbonate
• Insulin
• Glucose
• Hyperventilation

• Dialysis & cardiopulmonary bypass may be required

Monitoring

1. Esophageal or other core temperature probes
2. Three-way irrigating foley catheters → size appropriate for patient population
   • Urine meter x 1
3. Central line materials
   • CVP kits: size appropriate to patient population
   • Angiocaths: (4 ea.) (for IV access and arterial line – need to start an artline and more IVs)
   • Transducer kits for arterial & central venous cannulation

For dantroline

1. Syringes (60 ml x 5) to dilute dantrolene
2. Mini-spike® IV additive pins x 2 & Multi-Ad fluid transfer sets x 2 (to reconstitute dantrolene)

For additional treatment

1. IV access: 20G, 2-inch; 22G, 1-inch; 24G, ¾-inch
2. D5W 250 ml x 1 
3. Micro Drip IV set x 1
4. Large sterile Steri-Drape (for rapid drape of wound) – you may need to start CPR

For Cooling

1. Irrigation trays with piston syringe (x1) for NG irrigation
2. Toomey irrigation syringes (60 ml x 2) for NG irrigation
3. NG tubes (Size appropriate for patient population)
4. Rectal tubes [Sizes (Malecot Drain) 14F, 16F, 32F, 34F]
5. For Ice
   • Large clear plastic bags for ice x 4
   • Small plastic bags for ice x 4
   • Bucket for ice