No abstract

Infusion of propofol by a target-controlled infusion (TCI) system is effective in achieving conscious sedation for anxious patients presenting for dental surgery. It is a common clinical observation that anxious patients require more anaesthetic drugs than non-anxious individuals. In study 1 we have defined blood propofol concentrations necessary for conscious sedation in both anxious (n = 23) and non-anxious (n = 18) patients. The pump performance of the TCI system, using Gepts' pharmacokinetic model, was evaluated in these two patient groups. Subsequently, clearance of propofol was compared in the two groups. Mean measured venous serum propofol concentrations obtained between 20 and 35 min after the optimal sedation level was reached were 1.6 (SD 0.2) micrograms ml-1 in the anxious patients compared with 1.7 (0.3) micrograms ml-1 in the control group (study 1) and 1.4 (0.27) micrograms ml-1 in study 2. The pump systematically overpredicted measured propofol concentrations in both groups (study 1). There was no significant difference in propofol clearance between the two groups. In study 2, an optimized set of microconstants was derived which should more accurately predict the pharmacokinetic profile of the anxious population and this set was tested prospectively in another group of 12 anxious dental patients. Bias and precision with the optimized kinetic set were significantly less than the values obtained in study 1. We conclude that there was no significant pharmacokinetic differences between anxious and non-anxious subjects receiving subanaesthetic doses of propofol for conscious sedation.

Hypoventilation as a consequence of deep intravenous sedation is the most frequently reported cause of cardiac arrest during upper gastrointestinal endoscopy (UGIE). Haemodynamic stress can contribute to myocardial ischaemia; therefore, this study was designed to observe prospectively the cardiorespiratory changes during UGIE using either midazolam or propofol for conscious sedation. Thirty-four patients, aged 50 years and older, ASA physical status I-III, scheduled for elective UGIE with sedation, were studied. Oxygen saturation, heart rate, non-invasive blood pressure and Holter ECG were recorded continuously starting 15 min before sedation until 15 min after the endoscopy. In addition, plasma catecholamine concentrations were determined. The results of this study are consistent with previous reports that cardiopulmonary events may occur during endoscopy, with or without sedation. Both midazolam and propofol sedation may provide some protection against haemodynamic stress in response to insertion and manipulation of the endoscope, but sedation can also contribute to the occurrence of hypoxaemia.

No abstract

Computer controlled infusion of propofol can provide satisfactory and safe conscious sedation in dental patients.

The influence of sedative doses of propofol or nitrous oxide on the electroencephalogram was studied in 11 mentally handicapped patients with treated epilepsy undergoing dental procedures. At one session, propofol was titrated to achieve conscious sedation. The mean (+/- SD) dose requirements were 5.5 +/- 1.1 mg.kg-1.h-1. In six patients, the electroencephalogram was unchanged during propofol administration. In three patients, there was a decrease in epileptic activity, and in two patients, paroxysmal discharges disappeared. At another session, nitrous oxide was administered by nasal mask. The mean (+/- SD) concentration of nitrous oxide needed was 43.6% +/- 4.8%. The electroencephalogram did not change in nine patients, whereas in two patients epileptic activity decreased. There were no clinical epileptoid or other adverse manifestations during any treatment or up to 48 h thereafter. The results of the present study suggest that propofol or nitrous oxide can be administered in subanesthetic doses for conscious sedation in mentally handicapped patients with treated epilepsy.

Sudden movements from over-sedation during ophthalmic surgery can be detrimental to the eye. Bispectral index (BIS) and middle-latency auditory-evoked potentials (Alaris AEP index, AAI) were reported to be accurate indicators for the level of sedation and loss of consciousness. We assessed these monitors during sedation with special emphasis on preventing over-sedation. One-hundred patients scheduled for elective eye surgery were sedated with target-controlled propofol infusion and randomly allocated to BIS-guided, AAI-guided, BIS/AAI-guided, or clinically guided groups (n = 25 each). The initial target concentration was 0.5 microg x mL(-1) in patients >70 yr and 1.0 microg x mL(-1) in all other patients. The concentration was increased every 3 min by 0.1 or 0.2 microg x mL(-1), respectively until the patient had reached a BIS value of 75 (range 70-90) or an AAI of 40 (range 35-60). The surgeon who was blinded to group allocation assessed treatment quality after the procedure. Sedation was converted into general anesthesia in four patients because of excessive head movements. BIS was out of range 7% of the time vs 58% for AAI. No significant differences in treatment quality were observed among the four groups. We conclude that propofol sedation, guided by BIS or AAI monitoring, did not enhance ophthalmic surgical operating conditions over sedation guided by clinical observation only.

continuously starting 15 min before sedation until 15 min after the endoscopy. In addition, plasma ca-Hypoventilation as a consequence of deep intravenous techolamine concentrations were determined. The sedation is the most frequently reported cause of results of this study are consistent with previous recardiac arrest during upper gastrointestinal endoports that cardiopulmonary events may occur during scopy (UGIE). Haemodynamic stress can contribute endoscopy, with or without sedation. Both midazolam to myocardial ischaemia; therefore, this study was and propofol sedation may provide some protection designed to observe prospectively the cardioagainst haemodynamic stress in response to insertion respiratory changes during UGIE using either miand manipulation of the endoscope, but sedation can dazolam or propofol for conscious sedation. Thirtyalso contribute to the occurrence of hypoxaemia. four patients, aged 50 years and older, ASA physical status I-III, scheduled for elective UGIE with sedation, Keywords: conscious sedation, midazolam, propofol;upper gastrointestinal endoscopy, cardiorespiratory were studied. Oxygen saturation, heart rate, non-invasive blood pressure and Holter ECG were recorded changes, catecholamine release. Patients and methodsischaemia may result [3-5]. Forty consecutive patients, aged 50 years and older, ASA physical status I-III, scheduled for elective UGIE Accepted March 1998 Correspondence: V. L. B. Oei-Lim.with sedation, were studied. Data from six patients