Anaesthesia — Sedation, Monitoring and Recovery, NMC MBBS licence examination syllabus (Nepal Medical Council).
Sedation, Monitoring and Recovery
Almost every death from procedural sedation follows two modest doses of two different drugs, given by someone who was also doing the procedure.
Sedating a patient for a reduction, a drainage or an endoscopy is the anaesthetic act a newly qualified doctor is most likely to perform with the least supervision. It is also where the avoidable deaths are.
This chapter is about how those happen and how they are prevented.
Sedation is a slope, not a setting
The most dangerous misconception is that sedation has levels you select. It does not. It is a continuum, and patients slide along it — with the same dose producing different depths in different people, and in the same person at different times.
Light sedation. The patient responds normally to speech. Airway and breathing are unaffected.
Moderate sedation. Responds purposefully to speech or light touch. The airway is usually maintained without help.
Deep sedation. Responds only to repeated or painful stimulus. The airway may obstruct and breathing may be inadequate.
General anaesthesia. Cannot be roused. Airway and ventilation must be supported.
The governing rule follows directly: you must be able to rescue a patient from one level deeper than you intended. If you plan moderate sedation, you must be able to manage a patient who becomes deeply sedated — because some will. If you cannot, you are not equipped to give the sedation you were planning.
The combination that kills
The characteristic sedation death is not a large dose of one drug. It is a modest dose of a sedative together with a modest dose of an opioid, each individually reasonable.
The two act on respiration through different mechanisms, and the effect of combining them is greater than adding them. A benzodiazepine dose that would be unremarkable alone can stop breathing in a patient who has already had an opioid for pain.
Two habits prevent most of this:
Give one agent at a time and wait for it to work. Sedatives take time to reach peak effect, and stacking further doses before that peak is how patients become over-sedated — the second dose arrives just as the first is taking hold.
Reduce the dose substantially in the elderly and frail. A dose that is routine at thirty can cause apnoea at eighty. Start low, go slow, and titrate to effect rather than to a number.
No doses appear in this chapter deliberately. They depend on the agent, the patient and — critically — on what else has already been given, which is precisely the interaction being described.
Why the saturation reassures you too late
This is the physiological point that catches people out, and it follows from the oxygen dissociation curve covered in the physiology chapter.
A patient breathing supplemental oxygen can stop breathing entirely and maintain a normal saturation for some time. The lungs hold a reservoir of oxygen, and the curve is flat at the top — so the number stays high while carbon dioxide accumulates and the patient becomes progressively more acidotic. By the time the saturation falls, the situation is already advanced.
So the saturation is a late warning, not an early one. What detects the problem earlier:
Looking at the patient. Is the chest moving? Is air actually moving in and out? Has the colour changed? Is the patient rousable?
Capnography, where it is available. It measures exhaled carbon dioxide, so the trace changes the moment ventilation stops — before any change in saturation.
💡 The organisational point matters as much as the technical one: one person's only job must be the patient. If the person giving the sedation is also performing the procedure, they are watching the procedure. That is not a failing of concentration — it is a predictable consequence of asking one person to do two things, and it appears repeatedly in analyses of sedation incidents.
Before you give the first dose
Everything needed to rescue the patient must be present and working before any drug is drawn up. Checking during an emergency is checking too late.
Oxygen, connected and flowing when needed.
Suction, working — tested, not merely present.
Airway equipment in the sizes you might need.
A means of ventilating the patient.
Intravenous access you have tested. A cannula that has tissued is a problem you cannot solve while managing an over-sedated patient.
And then one question, answered honestly: who will manage the airway if it obstructs? If the answer is "nobody in this room can", the sedation should not begin — the procedure waits, or it happens somewhere with the right support. That decision is far easier to make before starting than after.
Recovery: the drug outlasts the procedure
The most under-appreciated period is the one after the procedure finishes, and the reason is not obvious.
The procedure itself was stimulating the patient. Pain and handling were keeping them partly awake, opposing the sedative. When that stops, the stimulus is withdrawn while the drug remains — so sedation deepens after the procedure ends, exactly when attention is turning to notes, equipment and the next patient.
So monitoring continues until the patient is genuinely awake, not until the procedure is finished. Position them so the airway stays open, and keep oxygen and suction at hand.
Discharge requires more than being awake. The patient needs a responsible adult to accompany them, written advice about what was done and what to watch for, and clear instructions not to drive, operate machinery or make significant decisions for the rest of the day. Judgement is impaired for considerably longer than patients believe — a patient who feels fine and insists they can drive is describing their confidence, not their reaction time.
Two further points
Reversal agents exist but are not a plan. There are drugs that reverse opioids and benzodiazepines, and they have a place. But they do not remove the need for airway skills, they may wear off before the sedative does — leaving a patient who becomes re-sedated after apparent recovery — and relying on them encourages larger doses than were ever safe. The plan is careful titration; reversal is the rescue.
Consent still applies. A sedated patient cannot consent, so the discussion happens beforehand — what is planned, that they may not remember it, and what the risks are. Retrograde amnesia is a feature of some sedatives, so a patient who agreed to something during the procedure may have no memory of doing so, which is not valid consent.
Putting it together
Sedation is a continuum, and you must be able to rescue one level deeper than intended.
A sedative plus an opioid is more than the sum — most deaths involve modest doses of both.
One agent at a time, wait for the peak, and far less in the elderly.
Saturation falls late. Watch the chest and use capnography where available.
One person's only job is the patient.
Sedation deepens when the procedure stops, so recovery is a period of risk, not a formality.
No doses, saturation targets or discharge scores appear here: doses depend on the agent, the patient and what else was given, and scoring systems differ between institutions. Use your local protocol.
Syllabus points
Sedation is a continuum, not a setting
Rescue one level deeper than intended
Sedative plus opioid — the characteristic death
One agent at a time; far less in the elderly
Why saturation is a late warning
One person's only job is the patient
What must be ready before the first dose
Recovery deepens sedation; discharge criteria
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