Postoperative Cognitive Dysfunction More Prevalent Than Previously Thought

The prevalence of change in cognitive function (CCF) after surgery may be higher than previously thought in all age groups, researchers reported here at the 2018 Annual Meeting of the American Society of Anesthesiologists (ASA).

“What surprised us most in the study was the fact that the prevalence of chance in cognitive function was higher in our institution than reported in the literature,” said Ana Brito, MD, Centro Hospitalar do Porto, Porto, Portugal. “In fact, it has warned us of an emerging problem to deal with.”

While further studies are needed to confirm the findings, they also discovered that age, ASA classification, anaesthetic duration, intraoperative haemodynamic instability (IHI), and postoperative pain may be risk factors for the development of CCF.

The authors also said that using a simple achievement test, such as the Digit Symbol Substitution Test (DSST), may help to identify CCF.

For the current study, the researchers conducted a prospective audit of 146 adult patients admitted to Dr. Brito’s institution for elective surgery. They administered the DSST test to the patients before and after surgery and calculated the ratio between the postoperative and preoperative DSST results.

Of the patients, 78% were undergoing general surgery and urology procedures. They verified that 71 patients obtained a postop-to-preop DSST ratio of <1 and 75 had a ratio of >1, showing that the prevalence of CCF was higher than described in the literature. They also verified that 10.96% of the patients reduced the number of postoperative responses by at least 20% from preoperative responses.

They also found that in the <1 group, 46.5% were ASA 3, compared with 28% in the >1 group. Also, the average anaesthesia duration was 137.5 minutes in the <1 group compared with 127.1 minutes in the >1 group. Furthermore, the prevalence of both postoperative pain and intraoperative hemodynamic instability were higher in the <1 group.

“The next step is to analyse other risk factors, namely modifiable risks factors that can be identified, in order to have the most complete list of possible risk factors, so we can intervene if possible and reduce the prevalence of this problem in our institution,” said Dr. Brito.