Types of anaesthesia and what changes the risk
Big picture
- General anaesthesia (GA): unconsciousness + airway/ventilation support as needed.
- Sedation: from minimal (“relaxed”) to deep sedation; airway reflexes may be reduced.
- Regional anaesthesia: numbs a body region using nerve blocks (often with light sedation).
- Neuraxial: spinal or epidural (common for obstetrics and lower body surgery).
- Local anaesthesia: numbs a small area (often combined with minimal sedation).
General vs regional/neuraxial: trade-offs
| Technique | Potential benefits | Key risks/downsides | Common use cases |
|---|---|---|---|
| General anaesthesia | Predictable unconsciousness; immobility; controlled ventilation; suitable for long/major surgery | Airway instrumentation; aspiration risk; PONV; hemodynamic swings; rare awareness; rare malignant hyperthermia | Major abdominal/thoracic/vascular, head/neck, many cancer surgeries |
| Regional (peripheral nerve block) | Excellent site-specific analgesia; less systemic medication; can reduce opioids | Nerve injury (rare); local anaesthetic systemic toxicity (rare); block failure; hematoma risk if anticoagulated | Orthopaedics, limb surgery, some breast/abdominal wall analgesia |
| Spinal | Dense anesthesia for lower body; avoids airway instrumentation; good for C‑section | Hypotension; urinary retention; post-dural puncture headache; rare spinal hematoma/infection | C‑section, hip/knee, urology, lower abdominal/pelvic procedures |
| Epidural | Flexible dosing; excellent labor analgesia; can extend for surgery/post-op pain | Block failure/patchy block; hypotension; rare epidural hematoma/infection; catheter issues | Labor, major abdominal surgery analgesia, thoracic epidurals |
| Sedation (moderate–deep) | Faster recovery than GA for some procedures; avoids intubation in many cases | Airway obstruction/apnea (OSA, obesity); aspiration risk; hypotension; variable recall | Colonoscopy/endoscopy, interventional radiology, minor procedures |
Volatile (inhalational) agents vs TIVA (total intravenous anaesthesia)
Many modern general anaesthetics use either volatile agents (e.g., sevoflurane, desflurane; sometimes nitrous oxide) or TIVA (commonly propofol + short-acting opioid). Choice depends on patient factors, procedure, equipment, clinician preference, and—more recently—environmental impact.
| Approach | Common agents | Pros | Cons / side effects | Notes on cost & footprint |
|---|---|---|---|---|
| Volatile GA | Sevoflurane, isoflurane, desflurane; ± nitrous oxide | Rapid titration; widely familiar; robust across many settings | PONV can be higher than with propofol; atmospheric pollution (agents are vented); malignant hyperthermia trigger (rare) | Desflurane and nitrous oxide have high global warming potential; low-flow techniques reduce waste |
| TIVA | Propofol-based | Often lower PONV; smooth emergence; no volatile-triggered malignant hyperthermia | Requires infusion setup; risk of awareness if delivery is interrupted; propofol causes hypotension in some patients | Life-cycle analyses suggest lower climate impact than high-GWP inhaled agents in many scenarios |
Obstetric specifics (brief)
- Labor epidural is common for pain relief and can be extended if urgent C‑section is needed.
- Spinal is common for planned C‑section (fast, dense block) but hypotension prevention is important.
- General anaesthesia in obstetrics is less common; airway and aspiration risks can be higher in pregnancy.
Anticoagulants and neuraxial blocks: timing matters to avoid spinal/epidural hematoma. See Medicines to review.