Muscle Relaxants

Question 1

Risk of hyperkalemia?

Answer 1

Serious dysrhythmias and cardiac arrest

Question 2

Metabolism of sux?

Answer 2

Broken down by plasma or pseudocholinesterase (made in liver, present in plasma)

Question 3

Which patients have decreased pseudocholinesterase?

Answer 3

Pregnant
Renal failure
Hypothermia

Question 4

Scoline apnoea?

Answer 4

Inherited disease, of pseudocholinesterase, (enzyme is chemically different to normal enzyme with varying degree of activity and prolonged paralysis

Question 5

Treatment of Scoline apnoea?

Answer 5

Supportive, make sure adequate sedation for continuing mechanical ventilation of the lungs until mm power returns

Question 6

Which no -depolarizers are benzyl-isoquinolines?

Answer 6

Curare, alcuronium, atracurium, cis-atracurium, and mivacurium

Question 7

Which non-depolarizer are amino-steroids?

Answer 7

Vecuronium, rocuronium, and pancuronium

Question 8

Chemical structure of non-depolarizers?

Answer 8

Highly ionized and water-soluble. No penetration of lipid barriers such as BBB, or Placenta

Question 9

Physical properties of non-depolerisers?

Answer 9

Some are stored in a powder form requiring re-constitution with sterile water or saline - vecuronium

Other require the fridge/ pancuronium, rocuronium, atracurium and cis-atracurium

Question 10

Clinical effects of non-depolarizers?

Answer 10

Onset of paralysis is slower than sux, can take 90sec to 5mins. No fasciculations occur due to no depolarization

Question 11

Whos’s at risk of hyperkalemia with suxamethonium admin, and therefore is contraindicated to use sux?

Answer 11

Renal failure patients K >5
Massive tissue injury (burn, crush injury)
Disuse of muscles over last few weeks/months (paraplegic, stroke patient.

Question 12

Which muscle relaxants are stored in the fridge?

Answer 12

Suxamethonium 
Pancuronium
Rocuronium 
Atracurium 
Cistracurium

Question 13

Which muscle relaxants aren’t store in the fridge?

Answer 13

Alcuronium
Vercuronium
Mivacurium

Question 14

Which two drugs undergo Hoffman degradation?

Answer 14

Atracurium

Cisatracuriun

Question 15

MM relaxants safe in renal failure?

Answer 15

Vercuronium
Atracurium
Cistracurium

Question 16

MM relaxants that release histamine?

Answer 16

Alcuronium
Atracurium
Mivacurium

Question 17

Which mm relaxants is useful in liver failure?

Answer 17

Cistracurium

Question 18

Dose of rocuronium, and it’s creature?

Answer 18

0,45-1,2mgkg
Stored in fridge
Low dose= slow intubation and short duration
High dose= intub within 60-90secs and long duration of action (1hr)
Cardiac stable

Question 19

Mivacurium’s acting time and relationship to sux?

Answer 19

10-20mins and rapid recovery

Similar do sux, degraded by plasma-/ pseudo-cholinesterase

Question 20

What normally breaks down ACh?

Answer 20

Acetyl cholinesterase

Question 21

How does a reversal work? And which ones for available?

Answer 21

It inhibits AChE, allowing more ACh to compete with NMB and displacing the from the cell.

Neostigmine, endrophonium, pyridostigmine

Question 22

What needs to be given with ACh inhibitors and why?

Answer 22

Anticholingeric acting on muscuraine receptors such as glycopyrrolate and Atropine to minimize autonomic effects of ACh

Question 23

What are the doses of mm relaxants?

Answer 23

Neostigmine 0,04-0,05mgkg
Glycopyrrolate 0,01-0,015
Atropine 0,02

Question 24

When is patient ready to be reversed?

Answer 24

Gag reflex, breathing, coughing, and eye opening

Needs patient co-op:
Sustained head lift (5-10secs)
Sustained hand squeeze
Sustained jaw grip

Question 25

What is the best way to determine if a patient is ready for reversal?

Answer 25

Peripheral never stimulation

Question 26

When can reversal safely be given?

Answer 26

Use train of four stimulation- >3twitches and >30mins since last dose of mm relaxants

Question 27

When do we do deep extubation?

Answer 27

Where coughing and buckling on ETT with extubation will cause complications.

In asthmatics, microvascular eye or ENT surgery

It is imperative that these patients fully reversed and breathing spontaneously, taking adequate tidal volume breaths.

Once extubated these patients must be monitored until fully awake, protective reflexes have returned and able to protect the airway

Question 28

What is peripheral nerve stimulation?

Answer 28

Monitors transmission across neuromuscular junction

Supra-maxima stimulus, the response of the mm is then observed

Question 29

How is PNS done

Answer 29

15-40mA used for ulnar nerve at wrist

Question 30

Which nerves can be used and how?

Answer 30

Ulnar, facial, common peroneal, posterior tibial

Nerves are superficial, and easily stimulated

2 elctrodes positioned with the black electrode over nerve and the other 2cm proximally over the path

Question 31

What is a twitch and when is it used?

Answer 31

1 short duration 0,1-1Hz stimulus, given automatically every 10secs

Used after given mm relaxants to check patient is paralyzed before intubation

Question 32

Train if four (TOF)?

Answer 32

Can be used to measure degree of neuromuscular block and assess for reversibility

4twitches of 2Hz each over 2secs

If non-depolarizing mm relaxant has been used you will see
-fade (1st >4th)

Maybe

Question 33

Signs of inadequate reversal?

Answer 33

Jerky respiration
Poor chest expansion with decreased tidal volume 
Tracheal tug
Restlessness agrravated by hypoxia
Inability to raise head from pillow 
Weak hand group poor ability to cough
Ptosis

Question 34

What is tetanus?

Answer 34

50-100Hz to detect any residual NMB you will see fade

Question 35

Double-burst Stimulation?

Answer 35

2short bursts of 50Hz stimulation, gives a better and more accurate visual representation of fade

Question 36

Post-tentanic facilitation or potentiation?

Answer 36

Used for more profound degrees of neuromusular block

5sec tetanus at 50Hz is followed by 3sec pause and 20 twitches at 1Hz

Number of contractions with determiner time required before reversal is feasible