Drug Misuse and Anaesthetic Implications Flashcards
Rank the most commonly used recreational drugs
- Cannabis
- Cocaine (all forms)
- Ecstasy
- Amphetamines
- Amyl nitrite (poppers/liquid gold)
- Hallucinogens
- Traquilizers
- Glues
- Opioid (heroin/methadone)
Categorize recreational drugs into 3 groups
SEDATIVES Gamma-Hydroxybutyrate (GHB) Benzodiazepines Opiates Cannabis
STIMULANTS Amphetamines Cocaine Ecstasy MDMA
HALLUCINOGENS
Lysergic Acid Diethylamine (LSD)
Phencyclidine (PCP) = Angel dust
Ketamine
Define drug misuse
Self administration of any drug in a manner that deviates from the approved medical or social patterns within a given culture
Describe the levels of drug dependence
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
Which 3 drugs cause the most problems for anaesthesia
Cannabis
Cocaine
Heroin
What is the nam of the Marijuana plant and what parts of the plant are used
Cannabis sativa (hemp plant)
- dried leaves
- flowers
- stems
- seeds
What is hashish?
A concentrated resinous form of cannabis –> ingestion or smoking
What chemicals are contained within the Cannabis sativa and what is the main active chemical
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
Describe the pharmacokinetics of cannabinoids
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.
How long does it take for complete elimination of a single dose of cannabinoids
14 to 30 days
How does significant and recent exposure to cannabis affect the anaesthetic
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
How do chronic uses of cannabis who have abstained for a short while affect the anaesthetic
They will be more tolerant to the effects of
- benzodiazepines
- opioids
- barbiturates
- phenothiazines
So larger doses will be required.
What is the name of the plant from which cocaine is extracted
Cocaine is an alkaloid extracted from the leaves of the Erythroxylon coca plant
- Snorted
- Dissolved in water for oral consumption
- injected
How is crack cocaine made and used
Addition of baking soda, water and heat to cocaine powder produces crack cocaine which can be smoked/injected/taken orally
What is the mechanism of action of cocaine
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)
How long do the immediate effects of cocaine last
If snorted: 10 - 30 minutes
If smoked: 5 - 10 minutes
How is cocaine metabolized
Rapid metabolism by plasma and liver cholinesterases to water soluble metabolites that are excreted in urine
What are the adverse effects of cocaine
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
How long should the cocaine period be for elective and emergency surgery in order to mitigate the pharmacological effects of cocaine
Elective: at least 1 week cocaine free
Emergency: Delay anaesthesia by 1 - 2 hours
- IABP
- ECG
- Temp
- CVP
monitoring before during and after anaesthesia
What are the limitations of local anaesthesia in cocaine users
Technical difficulties with regards to patient co-operation during the block or part way through the procedure
How can the cardiovascular response to cocaine be attenuated
- Generous premedication and analgaesia
2. Combination short acting beta blockers and vasodilators (Hydralazine, GTN, CCB)
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
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
Which induction and maintenance agents are safe to use in cocaine intoxication
Avoid Halothane (Sensitize myocardium to SNS) Avoid ketamine (SNS stimulation) Avoid etomidate (seizures in cocaine patient)
Propofol, thiopental, Sevo, Iso are ‘safe’
How does cocaine use affect analgaesia
Abnormal endogenous endorphin levels
Altered mew and kappa opioid receptor densities
Altered pain perception –> titration of postoperative analgaesia difficult
How does cocaine use affect SUX
Same metabolic pathway so cocaine may prolong the effects of SUX
What are the main opioids of misuse
Diamorphine (heroin) and morphine
How are diamorphine and morphine made
Produced from a naturally occurring substance extracted from the resin of the seed-pod of the Asian poppy (‘milk of the poppy’)
Describe the withdrawal syndrome
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
How does opioid addiction influence anaesthesia
- Induction and maintenance: lower dose for recent use, higher doses after abstinence or withdrawal
- High opioid doses for analgaesia (reprogram PCA)
What about local and regional anaesthesia in opioid misuse
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.
What are the three types of amphetamines and how are these purchased
Amphetamine
Metamphetamine
Dextroamphetamine
Often purchased on the street as a combination of all three
What are the effects of amphetamines
Increase dopamine to very high levels (enhancing mood and body movement)
Increase catecholamine concentrations
What are the effects of chronic metamphetamine misuse
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)
What is ecstasy
3,4 methylene- dioxy-methamphetamine or MDMA)
- synthetic chemical similar to methamphetamine
How does ecstasy/MDMA bring about its effect
Reduces re-uptake of serotonin within the CNS
Serotonin has an important role in regulating:
- Mood
- Aggression
- Sexual activity
- Sleep
- sensitivity to pain
How long do the effects of ecstasy last
3 - 6 hours but may last for several days
What are the adverse consequences of ecstasy
Malignant hyperthermia
Hyperthermia –? sweating –> dehydration __. acidosis and shock.
Response: ingestion of large quantities of water –> water intoxication and hyponatraemia –> seizures
What approach to anaesthesia should be taken in ecstasy users
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
Name four hallucinogens
LSD - Lysergic acid Diethylamide
Phencyclidine - PCP - angel dust
Ketamine
Psilocybin (magic mushrooms)
Are hallucinogens associated with physical dependence?
No but users do develop tolerance and psychological dependence
How do hallucinogens alter the anaesthetic approach
- Increased anaesthetic doses required if unsedated
- Attenuation of SNS CVS response. Monitor (IABP/CVP)
- Avoid drugs that increase SNS - atropine/ephedrine/ketamine/halothane)
- Clearance of SUX may be affected
- 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
Summarize the mechanisms of action for the hallucinogens
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
Name the recreational sedative drugs
Benzodizepines (temazepam, diazepam)
Barbiturates (pentobarbitol and quinalbarbital)
Flunitrazepam (Rohypnol/date rape)
Gamma Hydroxybutyrate (GHB)
What are the effects of flunitrazepam (Rohypnol)
It is a benzodiazepine that causes blackouts and short term memory loss –> effects last up to 8 hours
What are the effects of GHB
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
What are the implcations for anaesthesia with recreational sedatives
Decrease induction and volatile required
Pronounced respiratory depression with opioids
Withdrawal in postoperative period
List the recreational volatile agents (solvents)
Butane/isobutane/propane Chlorofluorocarbons Toulene/hexane/Xylene 1, 1, 1 - trichloroethane, trichloroethylene and tetrachloroethane Nitrites
Which demographic generally uses recreational volatile agents and why
Most often used by young children and adolescents as they are easily obtained, but they can be extremely toxic substances
What is the source of Butane, isobutane and propane
Cigarette lighter refills, fuel gas and aerosol propellants.
What is the source of Chlorofluorocarbons
Aerosols, refrigerants and fire extinguishers.
What is the source of Toluene, hexane and xylene
Adhesives, paints and thinners.
What is the source of 1, 1, 1, -trichloroethane, trichloroethylene (trilene) and tetrachloroethane
Degreasing agents and dry cleaning fluid.
What are recreational nitrites
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’.
What are the desired effects of the recreational volatiles
Short-lived alterations in mood and perception leading to feelings of euphoria ± hallucinations
What are the undesirable effects of the solvents
Sudden death Cardiac arrythmias Pulmonary hypertension Bronchospasm ARDS Methaemagolbinaemia Renal failure Pulmonary and cerebral oedema Liver toxicity (toxic liver metabolites - CP450)
What does chronic exposure to recreational volatile agents cause
Structural changes in the CNS
- Peripheral neuropathy
- Cerebellar degeneration
- Diffuse brain atrophy
What are the implications of anaesthesia in the setting of acute intoxication with recreational volatile agents
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
How long do most recreational drugs appear in the urine
1 - 3 days
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. 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.
Which drugs are detected on a ROUTINE drugs of misuse screen
Amphetamines, benzodiazepines, cocaine (metabolite), cannabinoids, methadone metabolite (EDDP) and opioids
All of the others need to be specifically requested.
