Morbidity and mortality in Anaesthesia

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Morbidity & Mortality in Anaesthesia–2025 Evidence Update

  • (incorporates NAP-7, ASOS, SAJAA & recent meta-analyses; figures are per anaesthetic unless stated)

Headline Incidence Figures

  • How we defined the groups
    • Non-high-risk = elective, ASA I–II, age < 65 y, non-cardiac/vascular/trauma surgery.
    • High-risk = ASA III–IV or age ≥ 65 y or major vascular, neurosurgical, emergency or trauma cases (i.e. where contemporary studies report the highest event rates).

Common Complications (≥ 1 %)

Complication Non-high-risk incidence High-risk incidence Everyday comparison†
Uncontrolled acute pain (day-1, VRS ≥ 4) ≈ 20 % ≈ 60 % Non-high-risk: like rolling a ‘6’ on a dice; high-risk: heads-or-tails
Moderate–severe PONV ≈ 10 % ≈ 70–80 % (untreated) Non-high-risk: chances of rain on any summer day in Cape Town; high-risk: almost certain without prophylaxis
Severe respiratory event (re-intubation / unplanned ICU) ≈ 0.15 % (≈ 1: 700) ≈ 4 % after major thoracic / cardiac surgery Non-high-risk: similar to annual risk of lightning fatality in SA; high-risk: like being admitted to an ED for any injury this year

Rare Complications (≤ 0.1 % in non-high-risk)

Complication Non-high-risk incidence High-risk incidence Everyday comparison†
Dental injury 0.05–0.3 % (≈ 1: 2 000–370) ≈ 1 % in difficult airways / maxillofacial cases High-risk ≈ odds of a fender-bender on the way to hospital
Peripheral nerve injury after nerve block (persistent > 3 m) 0.03–0.05 % (≈ 1: 3 000–2 000) ≈ 0.3–1 % in diabetic / neuropathic limbs High-risk: like drawing the Ace of Spades from a full deck
Peri-operative anaphylaxis ≈ 0.005 % (1: 20 000) ≈ 0.017 % (1: 6 000) in atopic / previous-allergy pts Even in high-risk, still < annual road-death risk
Intra-operative awareness ≈ 0.005–0.012 % (1: 19 000–8 300) ≈ 0.4 % (1: 250) in obstetric / major trauma High-risk: odds of being dealt a straight flush

Serious (life-threatening) Complications

Complication Non-high-risk incidence High-risk incidence Why it matters
Anaesthesia-attributable death < 0.0005 % (1: 200 000) ≈ 0.007 % (1: 14 000) ASA IV emergency Irreversible fatality
Peri-operative cardiac arrest 0.005–0.03 % (1: 20 000–3 300) ≈ 0.3 % (1: 330) ASA III–IV, emergency 30-day mortality ≈ 50 %
Peri-operative myocardial infarction ≈ 0.4 % (1: 250) in ≥ 45 y mixed surgery ≈ 1–3 % in major vascular / limb-ischaemia 10–15 % 30-day mortality
Peri-operative stroke ≈ 0.1–0.3 % (1: 1 000–330) ≈ 1–3 % carotid / cardiac / major vascular ≥ 50 % permanent deficit
Severe respiratory event (as above) See Table 1 See Table 1 Prolongs ventilation, ↑ mortality

†Real-life risk anchors: South-African road-fatality ≈ 1: 5 000 / yr; lightning death ≈ 1: 1 000 000 / yr.

General Anaesthesia

Complication Low-risk incidence High-risk incidence Real-life comparison
Common complications >1%
Moderate–severe pain day 1 1 in 5 3 in 5 Tossing a coin once vs. twice and getting “heads”
Post-op nausea / vomiting (PONV) 1 in 10 2 in 3 (if no prophylaxis) Non-risk: summer rain on one day; high-risk: Cape winter rain
Sore throat 1 in 5 1 in 3 (difficult airway) Like catching a common cold this season
Shivering / feeling cold 1 in 3 1 in 2 Odds of your next WhatsApp being from a family group
Drop in blood pressure needing medicine 1 in 7 1 in 3 Rolling a “1” vs “1–2” on a six-sided die
Severe complications
Dental damage 1 in 1 000–2 000 1 in 100 (severe airway problems) Low-risk: cracking a phone screen this year; high-risk: a fender-bender on the drive in
Peripheral nerve injury (position-related) 1 in 2 000 1 in 300 (diabetic / long surgery) Picking the joker from a full pack vs. drawing any face card
Drug allergy / anaphylaxis 1 in 20 000 1 in 6 000 (history of allergies) Annual chance of being struck by lightning vs. twice in a lifetime
Intra-operative awareness 1 in 8 000–19 000 1 in 250 (obstetric GA / major trauma) Low-risk: winning a very small lottery prize; high-risk: being dealt a straight flush
Unplanned ICU / re-intubation 1 in 700 1 in 25 Low-risk: yearly chance of lightning fatality; high-risk: ED visit for any injury
Myocardial infarction 1 in 250 1 in 20–30 (major vascular) Low-risk: lifetime risk of appendicitis; high-risk: drawing the Ace of Spades
Stroke 1 in 1 000–3300 1 in 50 (carotid / cardiac) Low-risk: driving 3 000 km; high-risk: serious car crash over a year
Cardiac arrest 1 in 20 000–33000 1 in 330 (ASA IV emergency) Low-risk: struck by lightning twice; high-risk: rolling two consecutive “snake-eyes”
Anaesthesia-attributable death < 1 in 200 000 1 in 14 000 Low-risk: lightning twice on the same day; high-risk: fatal road crash in SA this year

Spinal / Regional Anaesthesia (single-shot Spinal or Peripheral Nerve block)

Complication Low-risk incidence High-risk incidence Real-life comparison
Common complications >1%
Low blood pressure needing treatment 1 in 3 1 in 2 Flipping “heads” once vs. twice
Itching / warmth / shivering 1 in 4 1 in 3 Same odds as your next Uber being a Toyota
Nausea / vomiting 1 in 4 1 in 2 (no prophylaxis) Same as finding parking first try vs. second try
Urinary retention needing catheter 1 in 10 1 in 5 (older men, opioids) Rolling a “6” once vs. twice in a row
Post-dural puncture headache (spinal only) 1 in 200 1 in 50 (young females, large needle) Odds of losing luggage on a single flight
Failed / patchy block needing GA 1 in 20 1 in 10 (obesity, deformity) Drawing any heart from a deck vs. any red card
Transient nerve irritation 1 in 2 000 1 in 300 (diabetic / prolonged tourniquet) Low-risk: joker draw; high-risk: face card draw
Serious complications
Serious infection (epidural abscess) 1 in 10 000 1 in 5 000 (immunosuppressed) Odds of a house fire with damage
Epidural haematoma / permanent nerve damage 1 in 50 000–200 000 1 in 20 000 (anticoagulated) Winning a national raffle
High / total spinal → breathing help 1 in 5 000 1 in 1 000 (very elderly / large dose) Getting audited by tax authorities
Cardiac arrest from high spinal 1 in 100 000 1 in 30 000 Same as fatal lightning strike in SA
Death clearly due to regional < 1 in 100 000 < 1 in 50 000 Same as being a lottery jackpot winner
  1. Most patients fall in the non-high-risk column, where catastrophic events remain much rarer than everyday hazards like driving to hospital.
  2. High-risk profiles multiply (not create) danger–e.g., stroke rises from ~1: 1 000 to ~1: 50 in carotid surgery–and deserve tailored discussion and mitigation.
  3. Common symptoms (pain, nausea) dominate the lived experience, while fatal complications, though devastating, are statistically remote.

Context-specific South-African / African Data

  • Maternal anaesthetic deaths: Confidential Enquiry into Maternal Deaths (Savin 2023)–1.2: 100 000 live births; largely due to failed airway & high-spinal.
  • Resource factors: hospitals lacking 24 h critical-care outreach have 2.8-fold higher death after complication (failure-to-rescue).

African Surgical Outcomes Study (ASOS)

What Was Done

  • 7-day, prospective snapshot (Feb–May 2016) of 11 422 adults in 247 hospitals across 25 African countries.
  • All inpatient surgery (elective & emergency) included; followed until discharge

Headline Results

Metric Africa (ASOS) High-income cohorts (ISOS / EuSOS) Gap
In-hospital mortality 2.1 % 0.5 % ≈ 4 × higher
Elective mortality 1.0 % ≈ 0.1–0.2 % (ISOS elective subset) ≈ 5–10 × higher
Any post-op complication 18 % 17 % Similar
Death after a complication (“failure-to-rescue”) 5.6 % (≈ 1 in 18) 2.8 % (≈ 1 in 36) ≈ 2 × higher
Immediate ICU use 5 % of all patients; only 16 % of high-risk pts 15–20 % of high-risk pts (typical HIC audits) Critical-care shortfall

Risk-factor Profile

Africa (independent predictors of death/complication) Notes & contrasts with HIC
• Age ≥ 65 y (each decade ↑ risk)
• ASA III–V
• Urgent/emergency surgery (57 % of cohort)
• Major / complex procedures (GI, thoracic, neuro)
• Pre-existing sepsis or severe anaemia
• HIV infection (~11 % of patients)		 Same surgical risk factors appear in HIC studies, but HIV & marked anaemia are far less prevalent. African patients were younger (mean 38 y) and ostensibly “lower risk” (median ASA I–II), yet mortality was higher, pointing to system factors rather than biology.

Why the Mortality Gap Exists

  1. Failure-to-rescue: Similar complication rate, but double the death rate once complications occur.
  2. Scarce critical-care capacity: Median three ventilated ICU beds per hospital; < 1 % of all beds.
  3. Workforce shortage: Median 0.7 surgeons + obstetricians + anaesthetists / 100 000 population (vs 20–40/100 000 inflection point for safety).
  4. Limited ward monitoring / early-warning systems; delayed recognition of deteriorating physiology.
  5. Higher burden of communicable disease (HIV, TB) and untreated chronic disease.

ASOS authors’ Core Recommendations

  1. Couple access drives with safety investment–scaling surgery without postoperative surveillance will cost lives.
  2. Targeted postoperative monitoring of high-risk patients (age > 65, ASA III–V, urgent/major surgery, HIV+, anaemia).
  3. Expand critical-care / high-dependency capacity and ensure triage tools (e.g., ASOS Risk Calculator) guide bed allocation.
  4. Introduce early-warning scores, outreach teams, and rapid-response training on surgical wards–standard in most HIC hospitals.
  5. Strengthen the peri-operative workforce pipeline (specialist and nursing) and basic infrastructure (oxygen, monitoring, lab turnaround).
  6. Ongoing regional audits (ASOS-2, ASOS-3) to track progress and evaluate simple system interventions (e.g., twice-daily vital-sign rounds).
  • Bottom line: African surgical patients do not experience more complications than their HIC counterparts, but they are twice as likely to die when complications occur. Closing the gap hinges less on sophisticated technology and more on timely detection and rescue–trained staff, beds, and basic monitoring.

Risk Stratification

Patient Factors (independent Predictors; OR > 2)

  • Age > 65 yr, frailty (Clinical Frailty Scale ≥ 5)
  • ASA ≥ III
  • Severe obesity (BMI ≥ 40) or cachexia (BMI < 18.5)
  • Chronic kidney disease eGFR < 45 mL min⁻¹
  • Poorly controlled CHF / LVEF < 35 %
  • Recent (< 3 m) MI or unstable angina
  • COPD with FEV₁ < 50 % predicted
  • Insulin-treated diabetes
  • Active infection / sepsis
  • Hypercoagulable malignancy

Surgical / Organisational Factors

Category Relative risk vs baseline
Emergency surgery × 8 (ASOS)
Night-time start (20:00–07:59) × 2–3
Major vascular / open aortic × 5
Major thoracic/abdominal oncology × 3
Inadequate PACU nurse: patient ratio (> 3: 1) × 2
No HDU/ICU bed when indicated × 4 (failure-to-rescue)
Procedure Typical complication Incidence Mitigation
Arterial line Thrombosis, haematoma 0.2 % severe Ultrasound guidance, ≤ 20 cm H₂O flush pressure
Internal jugular CVC Pneumothorax, malposition, infection Mechanical 1–2 %; CLABSI 0.5–1 / 1000 cath-days US guidance, chlorhex 2 %+ alcohol prep, subclavian alt.
Femoral CVC CLABSI 20 %, DVT 20 % (≥ 5 d) Prefer IJ/SCV if feasible; full‐barrier removal at 48–72 h.
  • Mortality continues to fall in HICs but remains static in LMICs; ≥ 50 % of deaths are potentially avoidable (failure to rescue).
  • Cardiac arrest aetiology shifting: haemorrhage (17 %), brady-arrhythmia (9 %), myocardial ischaemia (7 %).
  • Anaphylaxis: Rocuronium, sugammadex and antibiotics now leading triggers; early IV adrenaline (10–20 µg boluses) halves mortality.
  • PPCs: protective lung ventilation (VT 6–8 mL kg⁻¹+PEEP ≥ 5 cmH₂O) lowers PPC by 30 %.
  • Data-driven risk models (e.g., Ex-PRESS, ARISCAT-SA) outperform ASA alone for predicting PPC & mortality.

Practical Pearls

  1. Quote population not ASA-attributable mortality when asked broad “death after anaesthesia” (2.1 % Africa vs 0.7 % HIC).
  2. Emphasise failure-to-rescue rather than surgical complexity as the main driver of African excess deaths.
  3. Mention NAP-7 if questioned on cardiac-arrest rates or causes.
  4. For device questions, state ultrasound guidance plus full barrier as evidence-based standard.
  5. Always discuss risk-mitigation bundles (checklists, early warning scores, protected PACU staffing).

Links

References:

  1. Braz, L. G., Braz, D. G., Cruz, D. S. d., Fernandes, L. A., Módolo, N. S. P., & Bráz, J. R. C. (2009). Mortality in anesthesia: a systematic review. Clinics, 64(10), 999-1006. https://doi.org/10.1590/s1807-59322009001000011
  2. Li J et al. Anaesthesia-related mortality 2017-2022: systematic review. Br J Anaesth 2023;131:964-75. pmc.ncbi.nlm.nih.gov
  3. Biccard BM et al. Peri-operative patient outcomes in the African Surgical Outcomes Study. Lancet 2018;391:1581-8. asos.org.za
  4. Royal College of Anaesthetists. NAP-7: Peri-operative Cardiac Arrest Report. 2023. rcoa.ac.uk
  5. American Heart Association. 2024 Guideline for peri-operative CV evaluation. Circulation 2024;149:e1-e95. ahajournals.org
  6. Gong J et al. Protective ventilation and postoperative pulmonary complications: meta-analysis. BMC Anaesth 2024;24:197. [bmcanesthesiol.biomedcentral.com](https://bmcanesthesiol.biomedcentral.com/articles/10.1186/s12871-024-02737-w?utm_source=chatgpt.com
  7. Guyer A C et al. Anaphylaxis 2023 practice parameter update. Ann Allergy Asthma Immunol 2023;131:211-23. annallergy.org
  8. DoH South Africa. National Patient Safety Incident Guideline v2, 2022.
  9. SAHPR A. Vigilance Guideline v4, 2024.
  10. Association of Anaesthetists. Peri-operative cardiac arrest epidemiology. Anaesthesia 2023;78:1458-70.
  11. Wang, Y., Wang, J., Ye, X., Xia, R., Ran, R., Wu, Y., … & Yao, S. (2023). Anaesthesia-related mortality within 24 h following 9,391,669 anaesthetics in 10 cities in hubei province, china: a serial cross-sectional study. The Lancet Regional Health – Western Pacific, 37, 100787. https://doi.org/10.1016/j.lanwpc.2023.100787

Summaries:

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© 2025 Francois Uys. All Rights Reserved.

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