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Diploma in Anaesthesia > Drug Misuse and Anaesthetic Implications > Flashcards

Drug Misuse and Anaesthetic Implications Flashcards

1
Q

Rank the most commonly used recreational drugs

A
  1. Cannabis
  2. Cocaine (all forms)
  3. Ecstasy
  4. Amphetamines
  5. Amyl nitrite (poppers/liquid gold)
  6. Hallucinogens
  7. Traquilizers
  8. Glues
  9. Opioid (heroin/methadone)
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2
Q

Categorize recreational drugs into 3 groups

A 
SEDATIVES
Gamma-Hydroxybutyrate (GHB)
Benzodiazepines
Opiates
Cannabis
STIMULANTS
Amphetamines 
Cocaine
Ecstasy
MDMA

HALLUCINOGENS
Lysergic Acid Diethylamine (LSD)
Phencyclidine (PCP) = Angel dust
Ketamine

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3
Q

Define drug misuse

A

Self administration of any drug in a manner that deviates from the approved medical or social patterns within a given culture

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4
Q

Describe the levels of drug dependence

A

Tolerance
- Ordinary effective concentrations no longer produce the desired effect (induction of normal clearance mechanisms and reduced receptor sensitivity)

Habituation
- Compulsion or desire to continue the use of a drug without actual physical dependence.

Physical dependence
- Withholding the drug will lead to a withdrawal syndrome

Addiction
- A combination of tolerance, habituation and physical dependence

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5
Q

Which 3 drugs cause the most problems for anaesthesia

A

Cannabis
Cocaine
Heroin

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6
Q

What is the nam of the Marijuana plant and what parts of the plant are used

A

Cannabis sativa (hemp plant)

  • dried leaves
  • flowers
  • stems
  • seeds
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7
Q

What is hashish?

A

A concentrated resinous form of cannabis –> ingestion or smoking

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8
Q

What chemicals are contained within the Cannabis sativa and what is the main active chemical

A

Main active chemical: ∆9-tetrahydrocannabinol (THC)

  • binds to specific cannabinoid receptors within the CNS
  • these receptors influence: pleasure, memory, thought, concentration, sensory, time perception, coordinated movement.
  • Relaxation and euphoria that last for several hours

Other cannabinoids also present

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9
Q

Describe the pharmacokinetics of cannabinoids

A

Highly fat soluble

  • accumulation in adipose tissue = long elimination T1/2
  • elimination T1/2 in chronic users = 28 h
  • elimination half life in occasional users = 56 h

Metabolism: Liver –> most of the breakdown products have psychoactive properties as well.

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10
Q

How long does it take for complete elimination of a single dose of cannabinoids

A

14 to 30 days

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11
Q

How does significant and recent exposure to cannabis affect the anaesthetic

A

PHARM
More sensitive to induction, volatile agents and opioids
(lower doses required)

CVS
Increase sensitivity of myocardium to myocardial depressant effects of volatile anaesthetics
(avoid drugs that cause tachycardia - atropine/ephedrine/ketamine)

AIRWAY and RESP
Increased airway irritability, bronchospasm, bronchitis, emphysema.

Severe upper airway oedema while undergoing anaesthesia –> Prevent and Rx with dexamethasone

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12
Q

How do chronic uses of cannabis who have abstained for a short while affect the anaesthetic

A

They will be more tolerant to the effects of

  • benzodiazepines
  • opioids
  • barbiturates
  • phenothiazines

So larger doses will be required.

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13
Q

What is the name of the plant from which cocaine is extracted

A

Cocaine is an alkaloid extracted from the leaves of the Erythroxylon coca plant

  • Snorted
  • Dissolved in water for oral consumption
  • injected
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14
Q

How is crack cocaine made and used

A

Addition of baking soda, water and heat to cocaine powder produces crack cocaine which can be smoked/injected/taken orally

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15
Q

What is the mechanism of action of cocaine

A

Prevents pre-synaptic uptake of the sympathomimmetic neurotransmitters

  • Noradrenalin
  • Serotonin
  • Dopamine

Also: Stimulates central SNS outflow

Circulating catecholamines may show a 5 x increase

Euphoria (Increase dopamine in the limbic system)
Tirelessness and power (Increased dopamine in the adrenal cortex and increased circulating catecholamines)

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16
Q

How long do the immediate effects of cocaine last

A

If snorted: 10 - 30 minutes

If smoked: 5 - 10 minutes

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17
Q

How is cocaine metabolized

A

Rapid metabolism by plasma and liver cholinesterases to water soluble metabolites that are excreted in urine

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18
Q

What are the adverse effects of cocaine

A 
Stroke (intense vasospasm)
Myocardial infarction (intense vasospasm)
Aortic dissection (sudden rise in BP)
SAH (sudden rise in BP)
LVH (Chronic high dose usage)
Dysrhythmia - AV block/sinus arrest (Chronic high dose usage)

Perforated nasal septum (vasospasm induced necrosis)
Cocaine induced thrombocytopaenia

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19
Q

How long should the cocaine period be for elective and emergency surgery in order to mitigate the pharmacological effects of cocaine

A

Elective: at least 1 week cocaine free

Emergency: Delay anaesthesia by 1 - 2 hours
- IABP
- ECG
- Temp
- CVP
monitoring before during and after anaesthesia

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20
Q

What are the limitations of local anaesthesia in cocaine users

A

Technical difficulties with regards to patient co-operation during the block or part way through the procedure

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21
Q

How can the cardiovascular response to cocaine be attenuated

A
  1. Generous premedication and analgaesia

2. Combination short acting beta blockers and vasodilators (Hydralazine, GTN, CCB)

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22
Q

How can the administration of a beta blocker alone cause problems in the attempt to attenuate the cvs response to cocaine. If beta blockade is attempted, what agents should be co-adminstered

A

Esmolol –> short acting beta blocker –> may enhance cocaine induced coronary vasoconstriction

Labetalol –> Mixed alpha and beta blocking effects BUT may still leave unopposed alpha effects

Vasodilators should be administered simultaneously to alleviate the potential harmful effects of beta blockers on their own

  • Hydralazine
  • GTN
  • CCB
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23
Q

Which induction and maintenance agents are safe to use in cocaine intoxication

A 
Avoid Halothane (Sensitize myocardium to SNS)
Avoid ketamine (SNS stimulation)
Avoid etomidate (seizures in cocaine patient)

Propofol, thiopental, Sevo, Iso are ‘safe’

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24
Q

How does cocaine use affect analgaesia

A

Abnormal endogenous endorphin levels
Altered mew and kappa opioid receptor densities

Altered pain perception –> titration of postoperative analgaesia difficult

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25
Q

How does cocaine use affect SUX

A

Same metabolic pathway so cocaine may prolong the effects of SUX

26
Q

What are the main opioids of misuse

A

Diamorphine (heroin) and morphine

27
Q

How are diamorphine and morphine made

A

Produced from a naturally occurring substance extracted from the resin of the seed-pod of the Asian poppy (‘milk of the poppy’)

28
Q

Describe the withdrawal syndrome

A 
Restless
Tachypnoea
Tachycardia
Hypertension
Mydriasis
Rhinorrhoea
Lacrimation
Piloerection

Dysphoria
Unconsciousness
Seizures

May occur within 6 hours and peak at 48 - 72 hours

Regular observation required for impending withdrawal

29
Q

How does opioid addiction influence anaesthesia

A
  1. Induction and maintenance: lower dose for recent use, higher doses after abstinence or withdrawal
  2. High opioid doses for analgaesia (reprogram PCA)
30
Q

What about local and regional anaesthesia in opioid misuse

A

Though local and regional anaesthetic techniques would appear to be a logical solution, as with cocaine users, there can be technical difficulties due to local and systemic infection and these patients are often non-cooperative.

31
Q

What are the three types of amphetamines and how are these purchased

A

Amphetamine
Metamphetamine
Dextroamphetamine

Often purchased on the street as a combination of all three

32
Q

What are the effects of amphetamines

A

Increase dopamine to very high levels (enhancing mood and body movement)

Increase catecholamine concentrations

33
Q

What are the effects of chronic metamphetamine misuse

A

Reduced motor speed
Reduced verbal learning

Long term effects
- Paranoia
- Aggressiveness
- Delusions
- Memory loss
- Visual/auditory hallucination
- Extreme anorexia
(may be taking large quantities of sedatives: self medication)
34
Q

What is ecstasy

A

3,4 methylene- dioxy-methamphetamine or MDMA)

- synthetic chemical similar to methamphetamine

35
Q

How does ecstasy/MDMA bring about its effect

A

Reduces re-uptake of serotonin within the CNS

Serotonin has an important role in regulating:

  • Mood
  • Aggression
  • Sexual activity
  • Sleep
  • sensitivity to pain
36
Q

How long do the effects of ecstasy last

A

3 - 6 hours but may last for several days

37
Q

What are the adverse consequences of ecstasy

A

Malignant hyperthermia

Hyperthermia –? sweating –> dehydration __. acidosis and shock.

Response: ingestion of large quantities of water –> water intoxication and hyponatraemia –> seizures

38
Q

What approach to anaesthesia should be taken in ecstasy users

A

Similar approach to cocaine

  • Generous premedication and analgaesia
  • Careful CVS monitoring
  • Attenuation of CVS response
  • Increase dose induction agents and volatiles but avoid use of older agents
39
Q

Name four hallucinogens

A

LSD - Lysergic acid Diethylamide
Phencyclidine - PCP - angel dust
Ketamine
Psilocybin (magic mushrooms)

40
Q

Are hallucinogens associated with physical dependence?

A

No but users do develop tolerance and psychological dependence

41
Q

How do hallucinogens alter the anaesthetic approach

A
  1. Increased anaesthetic doses required if unsedated
  2. Attenuation of SNS CVS response. Monitor (IABP/CVP)
  3. Avoid drugs that increase SNS - atropine/ephedrine/ketamine/halothane)
  4. Clearance of SUX may be affected
  5. Prolongation of analgaesic, sedative, respiratory depressant effects of opioids

The approach is similar to that of the approach to cocaine users because generally the hallucinogens activate the SNS –> Tachycardia, hypertension, hyperthermia.

High doses can cause respiratory depression, seizures, coma and death

42
Q

Summarize the mechanisms of action for the hallucinogens

A

LSD - Increases serotonergic action in CNS
PCP - Inhibits noradrenalin re-uptake and inhibits glutamate transmission
Ketamine (PCP derivative) - noncompetitive NMDA receptor antagonist that blocks glutamate.
Psilocybin - Increase serotonergic action in CNS

43
Q

Name the recreational sedative drugs

A

Benzodizepines (temazepam, diazepam)
Barbiturates (pentobarbitol and quinalbarbital)
Flunitrazepam (Rohypnol/date rape)
Gamma Hydroxybutyrate (GHB)

44
Q

What are the effects of flunitrazepam (Rohypnol)

A

It is a benzodiazepine that causes blackouts and short term memory loss –> effects last up to 8 hours

45
Q

What are the effects of GHB

A

Sedation and euphoria
Side effects: nausea, vomiting and seizures.

Metabolized to CO2 and water and therefore no measurable metabolites –> hard to detect with routine drug testing

46
Q

What are the implcations for anaesthesia with recreational sedatives

A

Decrease induction and volatile required
Pronounced respiratory depression with opioids
Withdrawal in postoperative period

47
Q

List the recreational volatile agents (solvents)

A 
Butane/isobutane/propane
Chlorofluorocarbons
Toulene/hexane/Xylene
1, 1, 1 - trichloroethane, trichloroethylene and tetrachloroethane
Nitrites
48
Q

Which demographic generally uses recreational volatile agents and why

A

Most often used by young children and adolescents as they are easily obtained, but they can be extremely toxic substances

49
Q

What is the source of Butane, isobutane and propane

A

Cigarette lighter refills, fuel gas and aerosol propellants.

50
Q

What is the source of Chlorofluorocarbons

A

Aerosols, refrigerants and fire extinguishers.

51
Q

What is the source of Toluene, hexane and xylene

A

Adhesives, paints and thinners.

52
Q

What is the source of 1, 1, 1, -trichloroethane, trichloroethylene (trilene) and tetrachloroethane

A

Degreasing agents and dry cleaning fluid.

53
Q

What are recreational nitrites

A

These are a particular group of volatile agents that include cyclohexyl, butyl and amyl nitrites (poppers). These can be obtained labelled as ‘video head cleaner’, ‘room odorizer’,‘ leather cleaner’ or ‘liquid aroma’.

54
Q

What are the desired effects of the recreational volatiles

A

Short-lived alterations in mood and perception leading to feelings of euphoria ± hallucinations

55
Q

What are the undesirable effects of the solvents

A 
Sudden death
Cardiac arrythmias
Pulmonary hypertension
Bronchospasm
ARDS
Methaemagolbinaemia
Renal failure
Pulmonary and cerebral oedema
Liver toxicity (toxic liver metabolites - CP450)
56
Q

What does chronic exposure to recreational volatile agents cause

A

Structural changes in the CNS

  • Peripheral neuropathy
  • Cerebellar degeneration
  • Diffuse brain atrophy
57
Q

What are the implications of anaesthesia in the setting of acute intoxication with recreational volatile agents

A

Airway protection
Big risk of cardiac arrythmia
Hepato-renal effects - choose drugs carefully
Lower doses of induction and inhalational anaesthetic will be required in the acutely intoxicated patient

58
Q

How long do most recreational drugs appear in the urine

A

1 - 3 days

59
Q

Perioperative cardiovascular instability is an important feature of anaesthesia in patients misusing the following drugs.

A.	Cannabis		
B.	Opioids		
C.	Cocaine		
D.	Amphetamines		
E.	Volatile agents		
F.	Hallucinogens
A

A. Correct. Cannabis can lead to a depressed sympathetic system.

B. Incorrect. Respiratory complications are more likely with the misuse of opioids.

C. Correct. Can often be very severe.

D. Correct. Amphetamines increase catecholamine concentrations.

E. Correct. With volatile agents, you need to be alert for rhythm problems.

F. Correct. There may be wide swings in BP and HR and an exaggerated response to ephedrine.

60
Q

Which drugs are detected on a ROUTINE drugs of misuse screen

A 
Amphetamines, 
benzodiazepines, 
cocaine (metabolite), 
cannabinoids, 
methadone metabolite (EDDP) and 
opioids

All of the others need to be specifically requested.

Diploma in Anaesthesia (73 decks)

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