Ambulatory surgery and anaesthesia outside the operating room
- Patient and surgery
Same-day surgery and sedation or anaesthesia given in places like endoscopy, scanners or the emergency room, with the same safety standards.
What it is
More and more anaesthesia happens away from the main operating theatre: same-day (ambulatory) surgery, and sedation or general anaesthesia in endoscopy, radiology and magnetic resonance imaging, cardiac catheter and interventional suites, electroconvulsive therapy, dental clinics and the emergency department. Ambulatory care depends on choosing suitable patients and procedures (stable disease, controlled obstructive sleep apnoea, a responsible adult to take them home, short procedures with little pain or bleeding) and on short-acting drugs, nausea prophylaxis, regional blocks and multimodal analgesia so that patients can go home the same day. Remote locations add their own hazards: unfamiliar rooms, distance from help and equipment, dim lighting, radiation, a shared airway with the proceduralist and, in the scanner, a strong magnetic field that turns metal objects into projectiles and needs compatible monitors. Sedation is a continuum from minimal to moderate, deep sedation and general anaesthesia, and the person giving it must be able to rescue a patient who drifts one level deeper than intended. The standard is the same as in theatre: pre-procedure assessment, a dedicated person watching the patient, oxygen, suction and airway equipment, pulse oximetry, blood pressure and, for moderate or deep sedation, continuous waveform capnography, which shows hypoventilation and apnoea before oxygen saturation falls.
What changes in this patient
- Patient selection: stable chronic disease, controlled obstructive sleep apnoea, adequate home support and easy access to care.
- Procedure selection: short, with limited pain, bleeding and fluid shifts, and low risk of airway complications.
- Remote site hazards: unfamiliar layout, distant help, limited space and lighting, radiation and old or different equipment.
- Shared airway in endoscopy and bronchoscopy: the anaesthetist has limited access to the face and mouth.
- Scanner hazards: magnetic projectiles, burns from wires, heating, noise and a patient seen only through a window or camera.
- Common sedatives: propofol, ketamine, a benzodiazepine with an opioid, and dexmedetomidine; reversal agents exist only for opioids and benzodiazepines.
Anaesthetic plan (and why)
- Assess the patient as for theatre: airway, ASA class, sleep apnoea, fasting and the planned depth of sedation — predicts rescue needs.
- Check the site before starting: oxygen, suction, airway kit, monitors, emergency drugs and how to call help — no surprises remote.
- Assign one trained person to watch the patient only — the proceduralist cannot sedate and operate safely at once.
- Monitor pulse oximetry, blood pressure, ECG as needed and continuous capnography for moderate or deep sedation — early warning.
- Titrate short-acting drugs in small steps and wait for effect — over-sedation comes from stacking doses.
- Respond to a flat or falling capnography trace with stimulation, airway manoeuvres and ventilation — prevents hypoxaemia.
- In the scanner, screen everyone for metal and use only compatible equipment — prevents projectile and burn injuries.
- Recover with the same scores and criteria as in the main unit and give written discharge advice — safe same-day discharge.
Reading the capnography trace during sedation
| Trace | Likely meaning | Action |
|---|---|---|
| Normal square waves | Breathing adequately | Continue to watch |
| Rising end-tidal values, slower rate | Hypoventilation from sedatives or opioids | Stimulate, reduce drugs, consider reversal |
| Flat line | Apnoea, complete obstruction or disconnection | Airway manoeuvres, ventilate, check the sampling line |
| Small waves with chest movement | Partial obstruction or laryngospasm | Jaw thrust, airway adjunct, positive pressure |
| Sloping, shark-fin shape | Bronchospasm or obstructed expiration | Treat bronchospasm |
Risks and complications
- Respiratory depression, airway obstruction and apnoea from over-sedation.
- Aspiration, particularly in emergency or endoscopic procedures.
- Laryngospasm and emergence reactions with ketamine; hypotension with propofol.
- Delayed help and equipment failure in remote locations.
- Unplanned admission after day surgery: pain, nausea and vomiting, bleeding or urinary retention.
- Magnetic resonance injuries: projectiles, burns and device malfunction.
Next step
- Recover until discharge criteria are met: stable vital signs, awake and oriented, pain and nausea controlled, able to walk, minimal bleeding.
- Discharge only with a responsible adult; advise no driving, machinery or important decisions for the next day.
- Give written instructions on pain relief, warning signs and who to call, and arrange a follow-up call where possible.
- Admit the patient if discharge criteria are not met; call a senior for airway events, aspiration or unplanned deep sedation.
- Report sedation events and equipment problems so that remote sites can be improved.
Test yourself
Think of the answer, then tap the question to see it.
Why is capnography recommended during moderate and deep sedation?
It shows hypoventilation and apnoea immediately, while pulse oximetry falls late, especially when the patient is breathing supplemental oxygen.
What does it mean to rescue from one level deeper of sedation?
The person giving sedation must be able to manage the airway and breathing of a patient who becomes more deeply sedated than intended, up to general anaesthesia.
What are the usual criteria for same-day discharge after anaesthesia?
Stable vital signs, awake and oriented, pain and nausea controlled, able to walk, minimal bleeding, and a responsible adult to take the patient home.
What is the main extra hazard of anaesthesia in the magnetic resonance scanner?
The strong magnetic field pulls ferromagnetic objects into the bore as projectiles; only compatible monitors, pumps and equipment may enter.
Elsewhere in DurgiPedia
- Opening the airway: head tilt, jaw thrust and simple adjuncts
- Supraglottic airway devices
- Informed consent: elements and how to obtain it
Connections
Educational content; it does not replace supervised training, your institution's protocols or the anaesthetist's or intensivist's decision. It contains no doses and no ventilator or infusion settings.
Sources: Procedural Sedation (StatPearls (NCBI Bookshelf), 2025); Capnography (StatPearls (NCBI Bookshelf), 2026).
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Representative model, for educational purposes only.