Oxygen administration and explicit memory: no improvement found in healthy volunteers.

It has been suggested that oxygen administration to healthy volunteers could improve their memory. We tested this hypothesis with a twin, double crossover, placebo-controlled study in 20 healthy non-smokers, allocated randomly to one of two groups. Blinded to the nature of the gas, group A breathed air first then oxygen on day 1, and then oxygen first, followed by air on day 2. Group B had all exposures in reverse order. After each gas exposure a written memory test with a list of 20 words was carried out and evaluated by a blinded observer. Recall after oxygen exposure (mean 8.3 words) was not significantly different from that after air exposure (mean 9 words).

An open, randomized comparison of alfentanil, remifentanil and alfentanil followed by remifentanil in anaesthesia for craniotomy.

We studied 52 adults undergoing elective craniotomy, allocated randomly to one of three opioid treatments: alfentanil 50 micrograms kg-1 followed by 0.833 microgram kg-1 min-1 until dural closure (group Alf.); alfentanil 50 micrograms kg-1 followed by 0.833 microgram kg-1 min-1 for 2 h, then remifentanil 0.25 microgram kg-1 min-1 (group Alf.-Remi.); or remifentanil 1 microgram kg-1 followed by 0.5 microgram kg-1 min-1 reducing to 0.25 microgram kg-1 min-1 after craniotomy (group Remi.). Anaesthesia was maintained with infusion of propofol and 66% nitrous oxide in oxygen. Infusions of propofol and remifentanil were stopped at head bandaging. Group Remi. had the least intraoperative haemodynamic responses and group Alf. the most (P < 0.05). Times to tracheal extubation and obey commands were similar in all groups. In all patients in group Alf.-Remi. and group Remi., the trachea was extubated 27 min from the end of anaesthesia; three patients in group Alf. were slower to recover. Use of analgesia in the recovery room and time to transfer to the neurosurgical unit were similar in the three groups.