2020B08 Discuss the adverse environmental effects of anaesthetic agents in current use



Greenhouse gas

·      Substance that absorbs and emits infrared radiation

·      e.g. CO2, N2O, methane, ozone

Anthropogenic global warming

·      Warming of average temperatures on earth caused by greenhouse emissions arising from human activity

·      Many detrimental environmental effects

Ozone layer

·      O3 rich region in the stratosphere

·      Absorbs UV-B


List of agents:

(descending order of toxicity)


·      Direct AGW: 6 hours at Fi 7% ≈ 1000kmg driving

·      0.02% metabolised; also resistant to environmental breakdown

·      Greater impact mostly due to long half life

Nitrous oxide

·      Direct AGW: 6 hours at Fi 50% ≈ 500km driving

·      Depletes ozone layer

·      Chronic exposure can cause neuropathy, teratogenicity, miscarriage in health care workers due to inactivation of methionine synthetase


·      Direct AGW: 6 hours at Fi 3.5% ≈ 50km driving

·      ~5% metabolised


·      Minimal impact on AGW, even after taking into account syringe driver, manufacture, procurement

·      Improperly discarded propofol is toxic to marine life

·      Syringes and tubing contribute to medical waste

·      Almost 100% metabolised; metabolites excreted in urine

·      Environmental effects of metabolites unknown


·      Minimal impact

·      Can be used as a sole agent

·      Minimal effects of ABC

·      Hence reduces need for other disposable equipment

Neuraxial/regional local anaesthetics

·      i.e. bupivacaine, ropivacaine, lignocaine

·      Minimal direct impact

·      Can be performed without sedation or general anaesthesia

·      Hence reduces need for other disposable equipment



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