ABSTRACT
This study examined the influence of mode of ventilation (spontaneous or controlled) on the target blood concentrations required to maintain anaesthesia with 'Diprifusor' (a target controlled infusion system for propofol) in 40 healthy, unpremedicated, adult patients undergoing knee arthroscopy. All patients were given alfentanil (10 micrograms.kg-1) and ketorolac (10 mg) immediately before induction and all received a 2:1 mixture of nitrous oxide:oxygen. An initial target blood concentration of propofol of 6.0 micrograms.ml-1 was used in most patients to induce anaesthesia. The blood target concentration required to produce acceptable anaesthetic conditions was not significantly influenced by the mode of ventilation. The mean maintenance target concentration for propofol was 3.9 (SD 0.83) micrograms.ml-1 in the ventilated group and 3.5 (SD 0.82) micrograms.ml-1 in the group of patients breathing spontaneously.
Subject(s)
Anesthetics, Intravenous/blood , Infusion Pumps , Propofol/blood , Respiration, Artificial , Adolescent , Adult , Anesthesia, Intravenous , Anesthetics, Intravenous/administration & dosage , Arthroscopy , Decision Making, Computer-Assisted , Drug Administration Schedule , Female , Humans , Male , Middle Aged , Propofol/administration & dosageABSTRACT
Seventy-four patients received general anaesthesia for Caesarean section. Seven percent of the elective group and 28% of the emergency patients reported dreaming or recall of voices during the procedure (p less than 0.05) at postoperative interview. One patient from each group reported feeling pain or suffocation. All patients were monitored for awareness using the isolated forearm technique and lower oesophageal contractility. Provoked lower oesophageal contractility was the most effective of the different indices. A value greater than 35 mmHg on at least one occasion had a false negative rate of 33%, a false positive rate of 28% and a predictive value of 25%. A value greater than 13 mmHg picked up all patients who dreamed, with a false positive rate of 68%. Both of the 'aware' patients had provoked lower oesophageal contractility response of greater than 70 mmHg, an attribute shared by only 8% of the rest. The isolated forearm was particularly ineffective.
