General, regional, local and sedation: what each one is
- Concept
Anaesthesia can put the whole person to sleep, numb one region of the body, numb one small spot, or calm the patient while they keep breathing on their own.
What it is
Anaesthesia means preventing the pain and distress of surgery or a procedure, and it comes in four broad forms. General anaesthesia is a drug-induced, reversible loss of consciousness from which the patient cannot be woken, even by painful stimuli; it combines unconsciousness, amnesia, analgesia and, when needed, muscle relaxation, and because it depresses breathing and the airway reflexes the airway and ventilation usually need support. Regional anaesthesia injects a local anaesthetic around the spinal cord (neuraxial: spinal or epidural) or around a nerve or plexus (peripheral nerve block) so that a whole region is numb and often weak while the patient can stay awake. Local anaesthesia numbs only the tissue at the operative site, by infiltration under the skin or by topical application. Sedation uses smaller amounts of sedative and analgesic drugs to relieve anxiety and discomfort; it is a continuum from minimal through moderate to deep sedation, and deep sedation can slide into general anaesthesia without a clear line. The techniques are often combined, for example general anaesthesia with an epidural or a nerve block for pain relief afterwards, or local anaesthesia with sedation. The choice depends on the patient, the operation and the team, and every technique needs monitoring, a plan for the airway and the readiness to convert to general anaesthesia.
Key points
- The components of general anaesthesia are unconsciousness, amnesia, analgesia, immobility and blunting of the stress response.
- Local anaesthetics act on nerves, not on the brain: they block voltage-gated sodium channels so impulses cannot travel.
- Spinal anaesthesia is a single injection into the cerebrospinal fluid; epidural anaesthesia goes into the epidural space, usually through a catheter that can be topped up.
- Monitored anaesthesia care means an anaesthesia professional monitors the patient and gives sedation as needed during a procedure under local or regional anaesthesia.
- Regional techniques avoid airway instrumentation and give good pain relief afterwards, but they need a cooperative patient, normal coagulation and time to work.
How it works
- General anaesthetics act on the brain: most enhance inhibitory GABA-A receptor signalling (propofol, the volatile agents), while ketamine blocks excitatory NMDA receptors.
- Local anaesthetics placed near a nerve stop sodium entry into the axon, so pain, then touch and movement, are lost below or beyond the block.
- Neuraxial blocks also block sympathetic fibres, so vasodilation and hypotension are expected effects.
- Sedation uses lower levels of the same drugs or others (benzodiazepines, opioids, alpha-2 agonists); as the level deepens, airway tone and breathing fall.
The four types at a glance
| Type | Acts on | Consciousness | Airway | Examples |
|---|---|---|---|---|
| General | The brain | Lost; no response to pain | Usually needs support (supraglottic airway or tracheal tube) | Laparotomy, most long operations |
| Regional | Spinal cord roots or a nerve or plexus | Kept, or with sedation | Patient breathes alone | Spinal for hip or caesarean, brachial plexus block for arm surgery |
| Local | Tissue at the site | Kept | Patient breathes alone | Suturing a laceration, removing a skin lesion |
| Sedation | The brain, lightly | Reduced, to a chosen level | Usually maintained; may need help when deep | Endoscopy, reduction of a dislocation |
In practice
- Patient factors: a predicted difficult airway or severe lung disease may favour regional anaesthesia; anticoagulation, infection at the site or refusal rule out a neuraxial block.
- Surgical factors: the site, expected duration, position and need for muscle relaxation; long abdominal or chest surgery usually needs general anaesthesia.
- Caesarean section is usually done under neuraxial anaesthesia, which avoids the airway risks of general anaesthesia in pregnancy.
- A regional block that is incomplete may need supplementing with local infiltration, sedation or conversion to general anaesthesia: plan this before starting.
- Local anaesthetic systemic toxicity can follow any block or large infiltration: know the maximum safe amount for the drug and have the rescue plan ready.
Next step
- Explain the options, their benefits and risks to the patient, and record the agreed technique and the backup plan in the consent.
- Whatever the technique, prepare monitoring, oxygen, suction, airway equipment and drugs for general anaesthesia before starting.
- Call a senior anaesthetist early if a block is failing, sedation is becoming deep or the patient cannot protect the airway.
- After a regional block, protect the numb limb and check that sensation and movement return as expected; report a block that lasts too long.
- Hand over the technique used and any problems to the recovery team.
Test yourself
Think of the answer, then tap the question to see it.
What are the components of general anaesthesia?
Unconsciousness, amnesia, analgesia, immobility (muscle relaxation when needed) and blunting of the stress response to surgery.
How does regional anaesthesia differ from local anaesthesia?
Regional anaesthesia blocks the neuraxis or a nerve or plexus so a whole region is numb; local anaesthesia numbs only the tissue at the operative site.
Why must whoever gives sedation be able to manage general anaesthesia-level problems?
Sedation is a continuum: a patient can drift one level deeper than intended, lose airway tone and stop breathing adequately, and must be rescued.
What are three reasons a neuraxial block may be ruled out?
Patient refusal, infection at the injection site and abnormal coagulation or anticoagulant use; raised intracranial pressure is another.
Elsewhere in DurgiPedia
- Informed consent: elements and how to obtain it
- Preoperative care: assessment, teaching, fasting, skin preparation and the checklist
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: General Anesthesia for Surgeons (StatPearls (NCBI Bookshelf), 2023); Procedural Sedation (StatPearls (NCBI Bookshelf), 2025).
Spotted a mistake?We are always improving for the community. Tell us what is wrong and our team will review it.Report a mistake
Representative model, for educational purposes only.