Anaesthetic risk

Life has never been as safe as it is today. In Europe, between 1900 and 1997, life expectancy at birth increased from 44 years to 74 years for males and from 45 years to 82 years for females.

Medical errors represent the fifth or eighth leading cause of mortality. In a Dutch study by Arbous, human failure contributed to (60% to 75%) of anaesthetic deaths and organisational factors to (10% to 40%).

Progress in the field of Anaesthesia has led to mortality rates of 0.5-1.4/10 000 procedures, for all patients, regardless of their ASA physical status, and to 2-10 deaths per million procedures for low-risk patients.

A recent French survey showed a more than twofold increase in anaesthetic procedures between 1980 and 1996, and considerable extension of anaesthesia for surgery in older and/or more severely ill patients, who would not have been previously considered eligible for surgery.

What is an acceptable level of risk?

Definitions

Risk

  • Hazard of loss, or the probability of incurring bad consequences or misfortune (negative)
  • Probability that a particular event occurs during a stated period or results from a particular challenge

Hazard

  • A situation that could lead to harm

Risk perception

  • Risk seeking
  • Risk neutral
  • Risk averse

Risk Characteristics

  • Likelihood
  • Severity, in general patients are more afraid of risks with a very low probability but greater severity
  • Controllability - People like control and the perception of being in control or having a choice downgrades the perceived severity

Compression bias

  • People have a natural tendency to overestimate rare risks and underestimate common ones.

Relative Vs Absolute risk

  • The relative risk of x occurring may be twice that of y occurring, but the absolute risk of either occurring may still be negligible

Communicating risk

No universally accepted method. Patients find it difficult to comprehend a figure. For example the quoted mortality following total knee arthroplasty 0.46% (one death per 217 procedures).

To bring this in to context I have seen it quoted to patients as " We have one death per year on this orthopaedic ward following knee replacement surgery"  It makes it more real to the patient yet does not seem to scare  them unnecessarily.

Road death risk in the UK is 1 in 10 000 during 1 year, Placed into context can be pictured as one person per year from the population of a small town.

Comparing risk: (figures are Canadian)

Anaesthesia 1 death : 20 000 procedures  
Driving car for 3-4 months 1.7 deaths per 10 000 drivers (Canadian driving figure, see above UK 1 year )
Low risk anaesthesia 1 death : 500 000 procedures one anaesthetic could be compared to the risk of 85 years of car driving, but is still 16 times more dangerous than taking an aeroplane.
Aeroplane flight 1 plane crash per 8 million flights  400* less risky than anaesthesia overall

UK lottery analogy:

Number of balls/ numbers Risk Risk per 100 000
3 balls 1 : 11 9091 : 100 000
4 balls 1 : 206 485 : 100 000
5 balls 1 : 11 098 9 : 100 000
6 balls 1 : 2796 763 0.04:100 000

GILL, GURDEV S. MD. MILLS, DAVID MD. JOSHI, ATUL B. MB, MCH(ORTH), FRCS. MORTALITY FOLLOWING PRIMARY TOTAL KNEE ARTHROPLASTY. Journal of Bone & Joint Surgery - American Volume. 85-A(3):432-435, March 2003.

Clergue, Francois. Public demand for greater safety: what solutions can be proposed? Current Opinion in Anaesthesiology. 15(2):225-226, April 2002.

Arbous, M. S. 1. Grobbee, D. E. 2. van Kleef, J. W. 3. de Lange, J. J. 4. Spoormans, H. H. A. J. M. 5. Touw, P. 6. Werner, F. M. 7. Meursing, A. E. E. 8. Mortality associated with anaesthesia: a qualitative analysis to identify risk factors. Anaesthesia. 56(12):1141-1153, December 2001.

Last updated 11/09/2015