Rates and statistics

Important definitions

• Perioperative mortality: commonly death within 30 days of surgery (all causes).
• Anaesthesia-attributable mortality: deaths primarily caused by anaesthetic management (rare in high-resource settings).
• Perioperative cardiac arrest: cardiac arrest during or around surgery; may be related to patient disease, surgery, or anaesthesia.

Anaesthesia-attributable mortality (high-income settings)

Contemporary reviews in very high human development settings report very low anaesthesia-related mortality, on the order of single-digit deaths per million anaesthetics in some analyses (definitions and capture methods vary).

Perioperative and anaesthesia-related cardiac arrest

A systematic review/meta-regression found that in high-HDI settings, anaesthesia-related cardiac arrest rates declined over time and in the 1990s–2010s were around 0.7 per 10,000 anaesthetics (with uncertainty intervals), while overall perioperative cardiac arrest rates were higher because they include surgical and disease-related causes.

ASA class and why risk rises steeply

Higher ASA Physical Status is consistently associated with higher postoperative complications and mortality across procedures and settings. For example, in a large ACS‑NSQIP outpatient cohort, overall 30‑day mortality was about 0.08%, and ASA IV status carried a markedly higher adjusted mortality risk compared with ASA I.

For procedure-specific risk (including the effect of ASA class), use the ACS NSQIP Surgical Risk Calculator.

Why very rare events still occur in “healthy” patients

• Anaphylaxis (rare)
• Aspiration (rare, but risk rises with “full stomach” states)
• Unanticipated difficult airway
• Unrecognized bleeding or occult disease