General toxicology

hrhodes's version from 2015-10-12 21:23


Question Answer
Features of drugs removed by HDSmall volume of distribution Low molecular weight Low protein binding Low lipid solubility Low endogenous clearance
6 examples of drugs amenable to HDalcohols carbamazepine lithium salicylate theophylline metformin induced acidosis
Drugs needing charcoal haemoperfusionTheophylline, valproate ( high protein binding)


Question Answer
What are the benefits of charcoalReduce absorption 50-60%, more effective that lavage or emesis, can reduce elimination even after absorption, cheap, available
What drugs do not work with charcoalAcids/alkalis, Hydrocarbons, metals, alcohols
How does MDAC work?Interupts enterohepatic circulation, GI dialysis
Name 5 drugs especially amenable to MDACTheophylline, Phenobarbitone, Carbamezipine, Quinine, dapsone
Complications CharcoalVomiting 30%, Aspiration, direct administration to lung via NGT, Mess, Corneal abrasion, bezoar, bowel obstruction and perf, Distraction of staff and consumption resources
Contraindications charcoalNon toxic, subtoxic dose, not ammeanable to charcoal (alcohol, metal, corrosives), Risk assessment suggests imminant seizures or reduced GCS, reduced GCS without airway protection, uncooperative patients
How do you give charcoal50g straight up, (1g/kg in kids), Either drink or NGT. If MDAC, for 25g every 2 hours


Question Answer
What is Whole bowel irrigationUsing volume to push the contents through the bowel. PEG_ELS, 2L/hr via NGT until clear effluent
IndicationsBasically bad stuff that charcoal no good and no good antidote. Fe >60mg/kg, CCB, slow release KCL, Lead poisoning, body packers
RequirementsNGT and cooperative pateitn, preferably ETT insitu as very unpleasant
ComplicationsBowle perforation, electrolyte disturbance, vomiting, aspiration, mess, distraction personal and consumption resources
Indications to cease WBIbowel distention or absent bowel sounds, clear effluent


Question Answer
General benefits of decontaminationReduced absorption of toxin possibly 50-60%, reduced requirement invasive and expensive antidotes and supportive care, reduced LOS, improve morbidity and Mortality
Negatives of decontaminationDistract nursing staff and resources, alter absorption of treatment and other drugs, aspiration, bowel obstruction and perforation

Urinary alkalinistaion

Question Answer
What drugs is urinary alkalisation useful in?Salicylates, phenobarbitone
How do you do urinary alkalisation?Correct K. Give 1-2mmol/kg iv NaHCO3 bolus, then add 100mmol NaHCO3 to a litre of 5% dextrose and run at 250mls/hr +/- 20mmol KCL. If this fails HD
ComplicationsHypokalaemia, hypoCa, alkalinsation

Decontamination and elimination

Question Answer
Name 4 methods of decontaminationInduced emesis, activated charcoal, gastric lavage, WBI
Name 4 methods of enhanced eliminationMDAC, Heamoperfusion, haemofiltration, urinary alkalisation


Question Answer
What 3 things do all deliberate poisoning patient need when planning disposition?risk assessment to determine medical disposition EARLY, social and psychiatric review
What factors affect disposition of patient?combination of risk assessment and discussion with toxicioogy can 1. period of observation in ED, then home, 2. extended observation in EOU (emergency observation Unit) or Gen med ward 3. ICU if need organ support
What general features make EUO ideal to safely observe fox patients?24hour availability of experienced medical staff, appropriate resources, staff and training, open plan environment that facilitates observation and ED ethos geared to assessment and disposition
What specific features do a EUO have for fox patients?Central nurse stations, environment protecting against self harm, secure entrance, dedicated area private interview, social work, pschy, D+A outpatient liaison services, monitoring/telemetry, resus equipment, duress alarm, appropriate staff, skills and equipment, 24/7/365 senior staff, nursepatient ratio 1:4, or 1:8
Criteria needed for EUO following poisoningNo cardiac monitoring, adequate sedation for delirium, risk assess not likely to deteriorate
Benefits of EUO for fox: Admissions in one place, experienced staff, medical staff available, security available, managed by people used to toxicology, reduced admission