Flumazenil is ABSOLUTELY contraindicated in a patient with a history of convulsions or thos e who have also ingested tricyclic antidepressants in whom it may precipitate fits and vent ricular arrhythmias. Acute with- drawal may result from the use of flumazenil in those pati ents addicted to benzodiazepines Activated charcoal is not indicated. CHAPTER 6 Poisoning and substance abuse 466 Cannabis Description Psychoactive substances derived from the plant Cannabis sativa. Mari- juana refers to any part of the plant used for its pharmacological effects; hashish is drie d resin from the flowers. Common names include: grass, pot, hash, reefer ganja, bhang, and spliff. Methods of abuse - Dried, then smoked or eaten - Occasionally injected. Clinical features These will depend on the mood, personality of the individual, environ- me nt, and the amount consumed. After smoking, the onset of effects is 10 \200\22330 minutes; after ingestion, 1 \200\2233 hours. Duration of effects, 4 \200\2238 hours. Low dose - Euphoria - Altered perception - Relaxation - Drowsiness - Hypertension, tachycar dia - Slurred speech - Ataxia, lack of co-ordination - Appetite stimulation - Injected conj unctivae - Dilated pupils. High dose - Acute paranoid psychosis - Anxiety, panic attacks - Confusion - Hallucinations and distortions of time and space. Intravenous abuse may result in diarrhea, nausea, vomiti ng, and abdomi- nal pain, as well as hypotension and pulmonary oedema. Management of psycho tic features is discussed on p.484. Immediate management Supportive therapy and observation is usually all that is required. Di aze- muls may be used for sedation, if required. Hypotension responds to intravenous fluids . SUBSTANCE ABUSE1 467 Cocaine/crack cocaine Description - Cocaine is an alkaloid from the leaves of the coca bush from South America. Cocaine: cocaine hydrochloride is a white crystalline powder or colorless crystals Crack cocaine: crack cocaine ( \200\230crack \200\231) is cocaine separated from the hydrochloride base, and usually sold as \200\230rocks \200\231. Methods of abuse - Cocaine is \200\230snorted \200\231 (sniffed) or injected intravenously - Crack is smoked. Clinical features When cocaine is snorted, effects occur very rapidly and may last up to 90 minutes. Smoked crack produces its maximum effect in about 10 minutes and has begun to wea r off after about 15 \200\22320 minutes. Mild/moderate intoxication - Euphoria - Slurred speech and ataxia - Restlessness, tremor, a gitation, and aggression - Hallucinations - Pupillary dilatation - Nausea and vomiting - Pa llor, cold sweats - Tachycardia, tachypnoea, ventricular ectopics/arrhythmias, hypertension. Severe intoxication - Drowsiness and coma - Convulsions - Incontinence - Hyperreflexia - Ci rculatory and respiratory failure \200\224leading to hypotension, hypoxia, and arrhythmias Severe hypertension \200\224leading to stroke, intracerebral hemorrhage, and infarction Artery spasm \200\224leading to myocardial and intestinal ischaemia and AMI - Hyperthermia. A paranoid delusional state may occur with chronic usage. Psychotic reac- tions to individ ual doses may also occur. Hallucinations may also occur. Severe depression and aggression may follow the \200\230high \200\231 and may result in suicide attempts or violent behavior against others. Pneumothorax may be found as a result of valsalva maneuvers per- formed to increase the absorption of inhaled cocaine. CHAPTER 6 Poisoning and substance abuse 468 Immediate management The patient should be assessed in a quiet environment. - Monitor: ECG, pulse, BP - Establish and maintain a patent airway; ensure intravenous access - Diazemuls for fitting, agitation, or psychosis (also reduces hypertension agitation and tachycardia) Transfer to hospital. If transfer is likely to be prolonged or delayed, hyperthermia should be treated with tepid sponging. Cold intravenous fluids may be necessary. Activated charcoal can be given within one hour of oral ingestion if hospital transfer is likely to be prolonged. SUBSTANCE ABUSE1 469 Ecstasy Description Ecstasy (3,4 methylenedioxymetamphetamine, MDMA) is a derivative of amp hetamine. Methods of abuse Oral ingestion. Clinical features - Euphoria and increased sensuality - Dehydration - Hyperthermia - Agitat ion - Convulsions - Muscle spasm - Abdominal pain - Hypotension - Coma - Cerebral hemorrhag e and infarction - Cardiac arrhythmias. Effects of chronic use include anorexia, palpitatio n, jaw stiffness, teeth grinding, sweating, and insomnia Immediate management - Intravenous access - Monitor ECG - Diazemuls for fitting, agitation, or psychosis (also reduces hypertension agitation and tachycardia) Activated charcoal can be given within one hour of oral ingestion if hospital transfer is l ikely to be prolonged. If transfer is likely to be prolonged or delayed, hyperthermia shoul d be treated with damp sponging to reduce the core temperature. Cold intravenous fluids sho uld be considered. Transfer to hospital (SVT and hypertension can be treated after arrival, unless this is likely to be delayed). Note The common causes of death following ecstasy use appear to be arrhyth- mias (early) an d a hyperthermic neuroleptic malignant-like syndrome (late). CHAPTER 6 Poisoning and substance abuse 470 Gammahydroxybutyric acid Description GHB is sold (illegally) for body building and weight l oss. It is also used as a psychedelic agent. Methods of abuse Sold as a powder, GHB is dissolved in water and taken orally. Clinical features Symptoms are dose dependent and include: - Nausea - Diarrhea - Drowsiness , confusion, coma - Vertigo - Tremor - Extrapyramidal signs - Agitation - Bradycardia - Hyp otension - Cardiorespiratory depression (severe poisoning) - Fits. Immediate management - Monitor: BP, pulse, respiratory rate, and pulse oximetry - Check: BM stix - Diazemuls for fits - Atropine for bradycardia - Transfer to hospital. SUBSTANCE ABUSE1 471 Hallucinogenic fungi Description A wide range of fungi are ingested for their hallucinogeni c properties. The most common of these is Psilocybe semilanceata (liberty cap). Methods of abuse Oral ingestion. Clinical features Symptoms usually begin within 30 \200\22390 minutes following ingestion a nd include: - Nausea and vomiting - Abdominal pain - Dilated pupils - Hallucinations (visua l and auditory) - Agitation, tremor - Drowsiness - Depression. Immediate management - Evacuation to hospital - Diazemuls for sedation, if required. CHAPTER 6 Poisoning and substance abuse 472 Ketamine Description A dissociative anesthetic/analgesic. Methods of abuse - Commercial ketamine is injected intramuscularly or intravenously - Stree t ketamine is sniffed or smoked. Clinical features The onset of action is rapid and the psychological effects usually last l ess than one hour: - Euphoria - Psychological effects/confusion: Synaesthesia (experiencing a stimulus with the \200\230wrong \200\231 sense) - Out-of-body experiences - Depersonalization - Persistent repetition of acts or words Agitation - Aggression - Vomiting - Slurred speech - Blurred vision - Numbness - Dizziness and ataxia - Hypertension and tachycardia - Rarely, convulsions, cardiac and respiratory ar rest, raised intracranial pressure, and pulmonary oedema may occur. Emergence reactions may be profoundly unpleasant including vivid dreams, hypersensitivity t o light, and hallucinations. Immediate management - Monitor: pulse, BP, ECG, and pulse oximetry - The patient should be maintained wherever possible in a quiet dark environment to reduce emergence phenomena. Dia zemuls may be used for agitation and will also reduce emergence symptoms. Transfer to hospital. SUBSTANCE ABUSE1 473 Lysergic acid diethylamide (LSD) Description A synthetic hallucinogen. Methods of abuse Usually ingested, either impregnated onto small squares of paper or as tab lets or capsules. Rarely, taken intravenously, nasally, or by smoking. Clinical features Effects are usually seen within an hour after oral ingestion; more rapidl y after intravenous abuse. Patients may present with a \200\230bad trip \200\231: Hallucinations (usually auditory) - Acute anxiety state (anxiety, panic, agitation, sweatin g, piloerection) - Aggression - Confusion. Other effects include: - Coma - Nausea, vomiting - Dilated pupils - Tachycardia, tachypnoea - Visual disturbance - Weakness, tremor, ataxia - Salivation, lacrimation - Focal neurolog ical deficit - Acute psychosis with behavioral change, hallucinations, paranoia, and mania may occur. Immediate management - Monitor: pulse, BP, pulse oximetry - The patient should be maintaine d in a quiet, dark environment with minimal stimuli and gently reassured. Diazemuls should be used if sedation is necessary or to control fitting.