Severe head injury in children produced a modest decrease in cerebral blood flow but a much larger decrease in cerebral oxygen consumption. Absolute hyperemia was uncommon at any time, but measured cerebral blood flow rates were still above the metabolic requirements of most children. The clear relationship between the frequency of cerebral ischemia and hypocarbia, combined with the rarity of hyperemia, suggests that hyperventilation should be used with caution and monitored carefully in children with severe head injuries.

and lInstitute of Psychosomatic Research, Herbsthalde 11, 7000 Stuttgart 1 FRG 1 The possible interaction (as indicated by rat experiments) between calcium channel blocking agents and benzodiazepines has been evaluated in nine healthy subjects. 2 Subsequently to an intravenous loading dose (0.07 mg kg-1) midazolam was infused for 6 h (0.035 mg kg-' h-1) and steady state plasma levels between 54 to 114 ,ug 1-1 were achieved. Two hours after the bolus of midazolam a solution of 20 mg nitrendipine or placebo was administered in a randomized, double-blind crossover fashion. 3 The marked sedative-hypnotic effects of midazolam as assessed by visual analogue scales (about four fold increase in the sedation index) and choice reaction time (100% prolongation) indicated some form of adaptation or tolerance towards the end of the infusion. However, the midazolam-induced impairments were not affected by nitrendipine. 4 EEG-data indicated stabile benzodiazepine-like effects during the complete infusion period of midazolam (e.g. decrease in alpha activity, increase in sigma, delta 2 and beta 1 activity). Again, these alterations were not modified by nitrendipine. 5 There was also no pharmacokinetic interaction between both agents, since elimination of midazolam (t½ -2.5 ± 0.8 h; CL -548 ± 143 ml min-') was in close agreement with control values (t½ = 2.4 ± 0.6 h; CL = 512 ± 102 ml min-'). Likewise, plasma levels of nitrendipine were comparable to literature data. 6 Thus, it could be concluded that nitrendipine does not affect the action of midazolam and therefore a direct involvement of calcium at the benzodiazepine receptor site is unlikely under our clinical conditions.

This chapter discusses the anaesthetic management of elderly patients. It begins with an overview of physiological and pharmacological changes of advanced age. It then describes particular anaesthetic management of the elderly patient with a view to optimizing outcome and avoiding post-operative cognitive dysfunction.