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The Pharmaceutical Journal Vol 265 No 7114 September 16, 2000
Pharmacy Practice Research
Papers presented at the British Pharmaceutical Conference, Birmingham, September 10 to 13, 2000 pR57

Are general ICU patients optimally sedated while receiving propofol?

By S. J. Beggan, P. E. Deady, J. P. Dade and H. Chrystyn*

Introduction Propofol is used extensively for sedation in intensive care units (ICU) around the UK. Its sedative properties fulfil many of the attributes of the theoretical ideal agent1 but under-sedation and over-sedation are still clinical problems.2 Studies have demonstrated the benefits of close monitoring of sedation of ICU patients such as reduced costs and decreased duration of ventilation and ICU stay.3 However, none have addressed the issue of titrating propofol doses to the patients' sedation scores. The aim of this study was to evaluate the current practice with regard to prescribing and dosing of propofol in relation to sedation scores. The data collected was used to formulate local guidelines in conjunction with ICU consultants and staff. Practice is to be re-evaluated following implementation of the guidelines.

Method Patients were excluded if they had received a propofol infusion for less than 24 hours, had received concurrent infusions of midazolam, were bilateral above-knee amputees or were paralysed. The initial part of the study was carried out retrospectively using medical notes from 70 patients admitted to ICU within the previous six months. A sample of 70 was chosen to achieve a target recruitment of 50, the sample consisted of consecutive patients who remained on ICU for =24 hours. Data from their ICU chart were collated from a 24-hour period from when the propofol infusion was commenced. The dose each hour and all sedation scores documented were recorded. A comparison was made between the patient's weight and the initial dose of propofol, to see if propofol was dosed based on weight. A comparison was then made between the median dose of propofol administered in the 24-hour period and the median sedation score (Addenbrooke's sedation scale was adopted). Patient weights were analysed for linear correlation to the initial dose of propofol prescribed. The relationship between median dose of propofol and median sedation score was analysed for correlation using the Spearmans rank correlation test. A set of local guidelines was then formulated based on the data collected and in conjunction with current literature4,5 and discussion with the senior ICU staff. The next stage involved implementation of the approved guidelines, to be followed by re-evaluation of practice.

Focal points

  • The initial dose of propofol administered to ICU patients was not based on their weight
  • There was no correlation between median doses of propofol and the patients' sedation scores over a 24-hour period in the retrospective analysis
  • Current literature supports the use of close monitoring of sedation in ICU
  • There is a need for guidelines for titration of propofol infusions used for sedation in the ICU

Results From the 70 patients selected, 40 (57 per cent) fulfilled the criteria for inclusion in the study. Of these 40, 42 per cent (17) were female and 58 per cent (23) were male. The median (range) age was 66 (23-86) years and median weight was 65 (30-98) kg. The median (range) propofol dose was 120 (40-280) mg/hour and sedation scores were 5 (4-6). The results from the initial retrospective analysis showed no correlation between initial dose of propofol and patient weight (r=0.159, P>0.1). There was no correlation between median propofol doses and median sedation scores (Spearmans rank correlation test, r=-0.215, P=0.19). Sedation scores were recorded on average every 2.7 hours and the average sedation score for the 40 patients was 5.7 (scale 1-6).

Discussion The initial results demonstrated the need for a clear starting point when commencing propofol infusions. The absence of guidelines on dosage made it difficult to accurately estimate a suitable dose to start with which in turn made dose titration appear very random. Comparing propofol dose with sedation score was difficult due to the two different forms of data; this was compounded by incomplete sedation score documentation. For ease of dose titration to the desired level of sedation, it was suggested that sedation scores were recorded with other routine hourly observations. The average sedation score of 5.7 certainly suggested patients were over-sedated. The guidelines for doses based on weight were successfully launched and doses are now based on patient weight and sedation scores are recorded hourly. Education and training sessions with the ICU staff have increased awareness and understanding of basing propofol doses on weight. The beneficial outcomes for a more tailored approach to propofol prescribing include reduced over and under-sedation, fewer adverse events, faster recovery from prolonged infusions of propofol, and significant cost saving. It will be essential to re-audit practice to evaluate the overall effect of introducing the dosage guidelines.

Pharmacy department, Leeds Teaching Hospitals NHS trust, Leeds LS1 3EX; *school of pharmacy, University of Bradford, Bradford BD7 1DP

References

1. Marinella M. Propofol for sedation in the intensive care unit: essentials for the clinician. Respir Med 1997;91:505-10.
2. Shelly M. Sedation in the ITU. Care of the Critically Ill 1998;14:85-8.
3. Sedation monitoring service reduces costs, cuts duration of ventilation and ICU stay. Hosp Formulary 1999;34: 710-11.
4. Shepherd MF. Criteria for use of propofol in critically ill adults. Am J Hosp Pharm 1994;51:111-3.
5. Covington H. Use of propofol for sedation in the ICU. Crit Care Nurse 1998;18:34-9.