Influence of preoperative cognitive status on propofol requirement to maintain hypnosis in the elderly.

BACKGROUND: The loss of cholinergic neurones in the basal forebrain has been shown to correlate to the extent of cognitive dysfunction during ageing in humans and to the hypnotic potency of propofol in animal models. We examined how the preoperative cognitive status, as assessed by mini-mental state examination (MMSE), may interact with propofol consumption during anaesthesia in the elderly. METHODS: In a prospective study, we recruited 41 patients (65-99 yr) undergoing surgery for hip fracture. Femoral nerve block was performed for analgesia. Target-controlled infusion of propofol (Schnider's model) was adjusted to the bispectral index within the range 40-60. Multiple linear regression analysis determined whether age, BMI, gender, duration of anaesthesia, and preoperative MMSE score affected the propofol consumption (general linear model, Systat 8.0). RESULTS: BMI and MMSE score significantly affected the mean value of propofol consumption. A low MMSE score (below 19) was associated with an observed decrease in propofol requirement in patients >65 yr of age. No significant effect of age, gender, and duration of anaesthesia on the propofol consumption was observed. CONCLUSIONS: Propofol requirement to maintain hypnosis during general anaesthesia appears to decrease with deterioration in the cognitive status in the elderly. We suggest that a cognitive dysfunction linked to a cerebral cholinergic dysfunction may influence the brain sensitivity for propofol in aged patients.

[Postoperative ischemic acute stroke and thrombolytic therapy]. / Thrombolyse postopératoire immédiate dans un contexte d'accident vasculaire sylvien gauche.

Intravenous thrombolytic therapy for ischemic stroke was performed on a 75-year-old patient at recovery from cervicocephalic superficial surgery. The patient recovered totally from ischemic stroke and no neurologic sequelae was observed. Thrombolytic therapy must be performed in an intensive care unit in order to manage some bleeding events which can occur.

[Pathophysiology of post-operative cognitive dysfunction: current hypotheses]. / Physiopathologie de la dysfonction cognitive postopératoire du sujet âgé: hypothèses actuelles.

Post-operative cognitive dysfunction (POCD) has been reported after a variety of surgical procedures. POCD is associated with a decline in performance of activities of daily living of elderly patients and can cause substantial damage to family and/or to social support systems. The incidence of POCD in the first week after surgery is 23% in patients between 60 and 69 years of age and 29% in patients older than 70. Cognitive dysfunction was still present in 14% of patients over 70 at three month after surgery. The risk of POCD increases with age, and the type of surgery is also important since there is very low incidence of POCD after minor surgery. For many years, it has been known that general anaesthesia is associated with persistent changes in gene expression in the brain for at least 72 hours. These observed modifications suggest an interesting hypothesis to explain the side effects of anaesthetic agents on cognitive dysfunction, particularly in the elderly. The inflammatory response to surgery is consistent with the hypothesis that inflammation contributes to cognitive decline in the elderly. Most of the drugs administered during anaesthesia interact with the cerebral cholinergic system, which seems to be impaired with ageing. One can hypothesize that this cholinergic dysfunction is a potent factor in the pathogenesis of POCD. These findings have implications for the information provided before obtaining consent from elderly patients prior to surgery; a careful evaluation of mental status is mandatory for all elderly patients undergoing general anaesthesia. Perioperative physicians should be familiar with the prevention, diagnosis, and management of postoperative cognitive dysfunction.