Anaesthesia and Dementia

[Badri]

Recently there was an article in the Times News paper about a study carried out by French Researchers. They selected 9000 people over the age of 65 and found that within a decade 632 developed dementia. Out of this number they noted that 22.3% had received a general anaesthetic and 18.7% had not. They were going to present a paper at a conference in Barcelona to say that older people who had received at least one general anaesthetic were 35% more likely to develop dementia.

Although some feel that the link was a little vague, it is worth remembering that the elderly patients do carry some risk during gen. anaesthesia. This topic may need further research and study.

(This topic is also posted in General Topics)

[thomasgregorissac]

Dear sir,
The topic of dementia following anaesthesia posted by you is an excellent one.The risk of dementia is more after surgery, it could be multifactorial due to anesthetic drugs, stress prior to and following surgery, iatrogenic trauma(esp brain surgeries, cardiac problems etc.Geriatric population is more prone for this and they have a risk of co-morbidities too.I would like to share a very recent work on the same below which came in a dutch journal-Dtsch Arztebl Int. 2014 Feb 21;111(8):119-25. doi: 10.3238/arztebl.2014.0119.
Rundshagen I[/b]
Abstract
BACKGROUND:
Older patients in particular are vulnerable to memory disturbances and other types of cognitive impairment after surgical operations. In one study, roughly 12% of patients over age 60 had postoperative cognitive dysfunction (POCD) three months after surgery. This is an important issue in perioperative care as extensive surgery on older patients becomes more common.
METHOD:
Selective review of the literature.
RESULTS:
POCD is usually transient. It is diagnosed by comparing pre- and postoperative findings on psychometric tests. Its pathogenesis is multifactorial, with the immune response to surgery probably acting as a trigger. Factors that elevate the risk of POCD include old age, pre-existing cerebral, cardiac, and vascular disease, alcohol abuse, low educational level, and intra- and postoperative complications. The findings of multiple randomized controlled trials indicate that the method of anesthesia does not play a causal role for prolonged cognitive impairment. POCD is associated with poorer recovery and increased utilization of social financial assistance. It is also associated with higher mortality (hazard ratio 1.63, 95% confidence interval 1.11-2.38). Persistent POCD enters into the differential diagnosis of dementia.
CONCLUSION:
POCD can markedly impair postoperative recovery. The findings of pertinent studies performed to date are difficult to generalize because of heterogeneous patient groups and different measuring techniques and study designs. Further investigation is needed to determine which test instruments are best for clinical use and which preventive strategies might lessen the incidence of POCD.

[Badri]

Dear Dr Thomas,

Welcome to our Forum and thank you for your note. Please tell us what your message will be for your juniors who may anaesthetise an older patient.

Badri.

[uamohammed]

Hi everyone

It is a moot question what causes postoperative dementia. As a general physician who usually has opportunities to deal with surgical cases with medical problems, I have a few points to make.
Patients who are already on treatment with antihypertensives and anti-ischemic drugs such as nitrates in addition to anaesthetics do cause relative hypotension during both general and spinal anaesthesia. There is a difference between a relative hypotension and actual hypotension. In the former the sudden fall of blood pressure more than 30 or 40 mm of Hg without actually coming down to a very low level. There is a wide fluctuation in the blood pressure during induction period and later. This may not invite the attention it requires. All these changes may cause damage to the brain either transient or permanent.
In the case of diabetic patients who are on treatment, in most of the centres in these parts (I cannot say about the standards in Western countries) we don't monitor blood sugar during the procedure unlike blood pressure monitoring by anaesthetist. When posted for surgery, nil oral need to be maintained for a few hours only. But in actual practice it takes many long hours. Many factors contribute to this. If there are five cases, the case taken in the last suffers the longest leading to hypoglycaemia. I have noted many times when patients are posted for surgery in the morning, nurses enforce nil oral from previous night meal. It is any body's guess when the team of surgeon and anaesthetist join and start the surgery and how long will the surgical procedure last. All these may cumulatively cause hypoglycaemia of severe degree and inflict brain damage.
UA Mohammed

[Badri]

Mohammed,

You are absolutely right. Even in the so called advanced western countries some of these old patients wait far too long with "Nil by mouth" sign on their beds for their surgery. So much so not only are they hypoglycaemic they are also dehydrated. It does not happen in all hospitals but certainly does in a number of them. I have known 80+ yrs patients with fractures of neck of femur waiting for surgery and "nil by mouth" for 12 - 16 hrs. I am sure this did cause disorientation during the post operative period and their recovery was very prolonged. Their mental state never returned to normal. I wonder if the anaesthetists have anything to add.

Badri.

[gmohan]

Hello Mohammed,Badri,
please see Back to Basics summary on Dementia ,posted under Psychiatry.

G Mohan.