[Perioperative mortality. Risk factors associated with anaesthesia]

Perioperative mortality associated with anaesthesia has been closely monitored throughout half of the century. The breakthrough in anaesthesia safety occurred in the 80-ties and 90-ties of the last century, when we could witness 5-folded reduction in mortality associated with anaesthesia, i.e. from 1 death:2680 operations/anaesthetic procedures (the 50-ties of the 20 h century) to 1:10,000 (and even 20-folded reduction within the ASA 1 and 2 groups of the patients--1 death:185,000 procedures). However, the more detailed analysis showed that the perioperative mortality is significantly higher, namely 1 death: approximately 500 procedures, and in the ASA 5 group of patients 1:4.5 procedures; what is more meaningful, the numbers have not been changed since 50 years. This phenomenon supports the thesis of anaesthesia safety, however, it indicates the drawbacks within the models and scoring systems evaluating operative risk. Several available scoring scales which can predict death rate, at the same time are not able to assess the extent of the other than biological risk factors. The "extra-biological risk" (i.e. process of therapy) may in some cases increase the operative risk as a whole. The value of the operative risk, as the fraction given by predicted death rate, is located between the numbers 0 and 1 (or between survival and death in the binary model of the probability theory). Recognition of the "extrabiological risk" value depends however on the high sensitivity of the scales evaluating prediction of death rate.