Propofol Patient Maintained Sedation during hip and knee arthroplasty under Locoregional anaesthesia.

Nick Sutcliffe and Daniel Amutike.

Glasgow UK.

Aim: To assess the efficacy and safety of a modified TCI device for patient controlled sedation (patient maintained sedation) in the clinical setting.

Method: Patients scheduled for hip and knee replacement surgery under locoregional anaesthesia were recruited into the study. Thirty- six patients between the ages 41 – 84 years have been studied to date. Consent was obtain during pre-operative assessment, the patients were instructed in the use of the equipment and were able to operate a target controlled infusion devise of propofol to provide sedation during surgery under supervision of the anaesthetist. All patients received temazepam 10 mg pre-medication and had subarachnoid anaesthesia induced with 20 – 22.5 mg of bupivacaine, Epidural anaesthesia was instituted post operatively. Once the subarachnoid block was established the patient was taken into theatre and the TCI propofol was commenced at a target of 0.5 microgram/ml. The patient was positioned for surgery and then given the “patient push button” and allowed to control their sedation as they wished. A single button push increased the target by 0.1 microgram/ml. There was a lockout time of 4 minutes and a maximum target concentration of 3 micrograms/ml. All patients received oxygen 2L/min via the nasal cannula and were monitored with an electrocardiogram, non-invasive blood pressure and pulse-oximetry. Sedation was assessed every 5 minutes along with the calculated effect site and blood concentration of propofol. The surgeon was asked to grade the surgical field and general operating conditions on a visual analogue scale from 0 – 10. The patients were interviewed on the evening of surgery and asked about their experience and whether they would have the same type of sedation and anaesthetic if they required a second joint replacement in the future.

Results:

Patient satisfaction was high with all patients scoring the technique excellent or good.

The surgeon’s satisfaction with the technique was high, with respect to general operating condition and surgical field. All patients but one would have the technique again for a future similar procedure. Mean calculated blood and effect site propofol concentration was 0.57 ug/ml and 0.53 ug/ml respectively. None of the patients became over sedated, and the lowest recorded saturation was 93% which was before the commencement of nasal 0xygen therapy.

Conclusion: Patient maintained sedation with propofol during locoregional anaesthesia provides safe, effective and satisfactory sedation in clinical practice.

References:

1. MG Irwin, N Thompson and GNC Kenny. Patient Maintained sedation: Assessment of target controlled system. Anaesthesia 1997;52(6) 525 – 530.

2. N. Sutcliffe and D Amutike, Patient controlled sedation during locoregional anaesthesia. A chapter from the book: On the study and Practice of Intravenous Anaesthesia. 2000 Kluwer Academic Publishers.