Sedation is a drug induced depression of consciousness, a continuum culminating in general anaesthesia
3 levels of sedation
- MINIMAL: Normal response to verbal stimulus. Airway reflexes maintained. Patient remains spontaneously ventilating, no cardiovascular effects
- MODERATE: Purposeful response to verbal/tactile stimulus. Airway reflexes maintained. Spontaneous breathing adequate, no CV effects
- DEEP: Verbal respone with painful stimulus. Airway support may be required. Spontaneous breathing may be inadequate. CV stability usually maintained
- CONSCIOUS SEDATION
extension of “Moderate sedation”. Drug induced depression of consiousness, similar to moderate sedation except that verbal contact is maintained throughout.
- Being aware of local hospital policies/guidelines and national standards, e.g. SIGN guidelines, NICE 112 guidelines, RCOA curriculum
- More guidelines being issued by many other colleges e.g. Gastroenterologists, who use sedation independent of anaesthetists
- Patient selection. Ensuring early preop assessment that patients are suitable medically and psychologically
- Pre operative assessment. Including airway assessment, comorbidities. Fasting often debated, but safest to treat as with for general anaesthesia
- Monitoring. ECG/NIBP/Sats for mild to moderate sedation. Capnography if deep sedation. Verbal contact best form of monitoring.
- During procedure. Maintain verbal contact where appropriate, i.e. Explanation to patient of what's occurring, e.g. IV cannula etc, even when sedated.
- Pharmacology. Using appropriate drug choice, e.g. Opioid if painful procedure.
- Using “principle of minimal intervention” i.e. Single agent therapy where possible. - Take into consideration drug dose/metabolism/renal + liver function, obesity etc.
- Knowing environment and equipment. Resuscitation and airway equipment.
- Appropriately trained staff
- Recovery. Appropriate recovery time and area
- Patient factors. Poor patient selection, e.g. Psychologically or medically, e.g. Difficult airway, meaning procedure may need to be cancelled/abandoned, or potential airway disaster. Counselling patients re sedation, i.e. Awareness sedation is NOT GA
- Enviroment factors. Providing sedation in non hospital setting, or unknown setting, therefore unfamiliarity with equipment. Remote settings e.g. CT or MRI means help may not be easily at hand
- Pharmacology factors. Inappropriate drug choices, e.g. Excessive drug dosing, not allowing peak effect of agent. Not taking into account synergistic effects of some drugs. Using a deeper level of sedation than necessary, and not recognising this. Paradoxical excitement with some drugs e.g. Benzodiazepines causing further administration. Use of drugs/methods not familiar to operator e.g. Propofol TCI. Debate as to whether certain drugs should be used in non anaesthetic hands