Substance Abuse Flashcards
what is the dose of paracetamol ingested which is potentially fatal?
> 12 g in totoal
> 250mg/kg = likely
<150 mg/kg = unlikely
pathophysiology of paracetamol overdose
• mainly inactivated by liver by conjugation leading to 2 metabolites glucuronide or sulfate
o overdose, liver is overwhelmed metabolised in alternative pathway (p-450)
o result in toxic metabolite N-acetyl-p-benzoquinone imine (NAPQI)
o NAPQI inactivated by glutathione harm prevented
o glutathione runs out NAPQI reacts with hepatocytes and cause necrosis
how does N-acetycycsteine prevent harm of paracetamol?
replenishes glutathione stores
what are some of the RF for paracetamol overdose worsening
alcoholics
pt on p450 inducers eg anticonvulsants, rifampicin, St jon’s wart
clinical featres of paracetamol overdose
- N+V
- abdo discomfort at first
- pain and tenderness over liver (after 12 hours)
- jaundice (2-4 days)
- coma due to hypoglycaemia (after 1-3 days)
- hepatic encephalopathy (3-5 yrs)
- loin pain, haematuria and proteinuria initial renal failure
- bleeding coagulant abnor due to liver damage
- hyperventilation due to metabolic acidosis
- cerebral oedema, septicaemia and DIC causes fatality
- can be asymptomatic initially and if not severe enough
investigation for paracetamol overdose
• Paracetamol level level taken after 4 hours of ingestion
o or asap if staggered dose
• U&Es, creatinine AKI
• LFT if ALT > 1000 IU/L hepatotoxicity
• Clotting prothrombin time = best indicator of severity of liver failure
• Glucose hypoglycaemia risk
• FBC for platelets
• body weight needed for treatment calculation
management of paracetamol overdose
- Acute poisoning STAT dose of activated charcoal if within 4 hours of ingestion to dec absorption
- IV Parvolex (NAC) if on or above the of timed plasma paracetamol level –> 1st infusion (losing dose of 160mg/kg body weight over 1 hour), then 50 mg/kg over the next 4 hours, then 100 mg/kg over the next 16 hours
- Methionine can be used if refused IV Parvolex
- Liver transplantation occasionally needed for hepatic failure
Risk factors for getting opiate overdose
mental health conditions, financial problems, and crime
in a relationship that is protective
opiate dependence
alcohol –> enhance the sedative effect of opiate
hepatic impairment
renal impairment
- hypotension
- hypothyroidism
- Asthma
- prostatic hypertrophy
what is the most common cause of opiate overdose?
accidental overdose
intentional overdose
clinical features of opiate overdose
• if chronic problem constipation, N+V, loss of appetite, dependence
• Acute toxicity
o N+V
o Respiratory depression +/- cyanosis/coma/apnoea,
o hypotension
o tachycardia
o pinpoint pupils (miosis)
o non-cardiogenic pulmonary oedema (from heroin/other opioids)
investigation for opiate overdose
- urine drug screen (only detect presence but not quantity)
- baseline bloods FBC, U&Es, LFT, TFT, creatine kinase, ABG
- CXR if pulmonary oedema suspected
- AXR
- ECG arrythmias is possible from opiate toxicity
management of opiate overdose
• A-E assessment
o A – clear airway especially if resp depression
o B – ventilate on O2 if breathing inadequate due to resp depression
o C – IV access + bloods + ECG
IV naloxone (if no Iv access then IM) (0.4-2mg for adult, 0.01mg/kg for children)
• small dose then inc doses every 2-3 minutes if no response
o 0.04 mg
o 0.5 mg
o 2 mg
o 4 mg
o 10 mg
o 15 mg
• observe carefully for recurrence of CNS and resp depression
activated charcoal if ingested within 2 hours
Naltrexone for those who want to stay clean
what is Salicylate
aspirin - a derivative of salicylate which are present in high conc of oils and wintergreen
pathophysiology of salicylate overdose
• characterised by acid-base disturbances, electrolyte abnor and central nervous system effects
what are the doses of aspirin ingested will the person need admission
- ingested > 250 mg/kg aspirin = moderate toxicity
- > 500 mg/kg aspirin = severe and possibly fatal toxicity
ingested < 125 mg/kg aspirin & no symptoms do not require hospital admission
what are some of the risk factors for salicylate overdose
children and elderly late presentation pulmonary oedema, CNS features, hyperpyrexia metabolic acidosis salicylate conc above 700 mg/L
clinical features of mild salicylate overdose
N+V, tinnitus, lethargy or dizziness
clinical features of severe salicylate overdose
dehydration, restlessness, sweating, warm extremities with bounding pulses, inc RR, hyperventilation and deafness
uncommon features of salicylate overdose
hypokalaemia, haematemesis, hyponatraemia/hypernatremia, abnor blood coagulation (inc prothrombin ratio/INR) etc
• CNS confusion, disorientation, coma and convulsions
features of chronic salicylate overdose
anxiety, tachypnoea, diffuse sweating, difficulty concentrating, confusion, hallucinations and agitated delirium
what are the investigations for salicylate overdose?
1) plasam salicyate concentrations - severity of salicylate level at 2- 4 hours after ingestion & repeat another at 2 hours after the first level
2) bloods - FBC, U&Es, LFT, clotting, urinary pH (monitoring), blood glucose, ABG (risk of metabolic acidosis)
3) ECG - widen QRS, AV block, ventricular arrhythmia
what are the different acid-base staging of salicylate overdose
1) stage 1 - blood pH > 7.4, urine > 6 (respiratory alkalosis –> inc urinary excretion of bicarbonate)
2) stgae 2- blood pH > 7.4, urin pH < 6 - metabolic acidosis with compensating resp alkalosis, urinary hydrogen exrection, intrac-cellular potassium depletion
3) Stage 3 - blood pH < 7.4, urin pH < 6 - severe metabolic acidosis and hypokalameia
what is the management of salicylate overdose
if ingested within 1 hour - activated charcoal
aggressive rehydration
correct acid-base and electrolyte abnor
glucose infusion if hypoglycemia
vit K if hypoporthrombinaemia
urinary alkalization (IV sodium bicarbonate to inc poison elimination) - optimum urinary pH is 7.5 - 8.5
moderate to severe - hemodialysis
what are some of the complications for salicylate overdose
ARDS cardiac arrest seizures hepatitis Reye's syndrome (liver and brian damage in children < 20) renal failure DIC
definition of alcohol abuse
over a 12-this month period - Patients drinking has cause clinically significant impairment or distress (determined by the presence of at least 2 or more diagnostic criteria)
what are the 11 DSM V features of alcohol abuse
1) Alcohol is often taken in large amounts or over a longer period than was intended
2) persistent desire or unsuccessful efforts to cut down or control alcohol uses
3) great deal of time spent in activity necessary to obtain alcohol, use alcohol, to recover from its effects
4) craving or a strong desire or urge to use alcohol
5) recurrence alcohol use resulting in failure to fulfil major role obligation at work, school or home
6) continued alcohol use despite having persistent or recurrent social or interpersonal problems causing or exacerbated by the effect of alcohol
7) Important social, occupational, or recreational activities are given up or reduced because of alcohol use
8) recurrent alcohol use in situation in which is physically hazardous
9) alcohol use is continued despite knowledge of having a persistent or recurrent physical or psychological problem that is likely to have caused or exacerbated by alcohol
10) tolerance
a. a need for marked Lee increased amounts of alcohol to achieve intoxication or desire effect
b. a markedly diminished effect with continued use of the same amount of alcohol
11) withdrawal
investigations required for alcohol abuse
CAGE
AUDIT screening (Alcohol use disorder investigation test - the severity of alcohol misuse
LFT - inc GGT, AST> ALT
management of alcohol
o Initial structured brief advice [FRAMES model]
o Extended brief intervention – up to 5 sessions of motivational interviews, undertaken by a those with relevant training
o CBT/behavioural therapy
o Referral to a specialist alcohol treatment service - Can be given chlordiazepoxide (benzo) or sometimes diazepam
o Risk of malnourishment – oral thiamine
o Wernicke encephalopathy – IV thiamine
Feedback about the personal risk of impairment
Responsibility - personal responsibility
Advise to cut down
Menus of alternative drinking pattern
Empathic consultations
self-efficacy - an interview-style which improves the patient’s self-efficacy
