Patient-controlled premedication by i.v. midazolam for ambulatory surgery.

Applying the principle and equipment of patient-controlled analgesia, this double-blind randomised study was designed to determine the premedication dose of midazolam and to provide information about the need for preoperative anxiety control. The effects of patient-controlled premedication by i.v. midazolam were compared to those of a 1-hour i.v. infusion of a fixed dose of 4 mg. Two groups of 25 patients were studied prior to ambulatory surgery. Using a visual analogue scale graded from 0 (no anxiety) to 100, anxiety and short-term memory as well as vital signs, vigilance, cognition and orientation were assessed before premedication and then every 20 min until admission to the operating room. In both groups, 40% of the patients were free of anxiety before premedication. Sixty-four percent of patients in the self-pre-medicated group never used the pump. The dose of midazolam was only 0.7 0.2 mg (mean SD) in this group taken as a whole, 0.7, 1.1 mg (mean SD) in the 8 patients who had an anxiety score at least equal to 50 before premedication, and 1.7 0.3 mg (mean SD) in the 9 patients who chose to push the button of the patient-controlled device. Anxiety and short-term memory scores decreased significantly and similarly in the self-premedicated group and in the fixed-dose group. For similar intraoperative anaesthetic requirements, time from the end of anaesthesia for determining whether a patient was ready for admission to the postrecovery lounge was shorter in the self-premedicated group (26 +/- 8 min vs 32 +/- 8 min; mean +/- SD. Reduced doses of midazolam self-administered via a patient-controlled device can result in a relaxed preoperative period and amnesia in ambulatory surgery patients. However, the level of anxiety before premedication was low, which calls into question the legitimacy of the patient-controlled premedication in this kind of population. The expense of the pump was not justified by the small number of patients using it, probably because they were worried by the technical nature and the invasiveness of this technique.

[The sheep: an animal model for ligament prostheses?]. / Le mouton: modèle animal pour les prothèses ligamentaires?

Ruptures of the anterior cruciform ligament is difficult to repair. Ligament prostheses are sometimes useful. We tested a ligament prosthesis which had the original property of combining a polyester braid with a matrix favouring collagen ingrowth. We implanted this prosthesis in the knee joint of 10 sheep after sectioning the anterior cruciform ligament at it origin. The ligaments were recovered after 6 months. We studied the functional and radiographic results. Tolerance was studied in samples of the articular fluid and synovial tissue. We evaluated bone attachment and fibrous growth using micro-radiography and specific coloration techniques. Samples were examined under electron microscope. No rupture was encountered. We observed a satisfactory functional and radiographic result. No intolerance was observed. The neoligament had a bony or mixed attachment in 60% of the cases and was comprised of oriented tissue in 90% of the cases. Vascular invasion was important. These findings are promising and suggest that long-term studies should be undertaken.