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to placebo3. Is MgSO4 as effective as lidocaine in preventing pain on injec-

tion of propofol?

Methods: Prospective randomised controlled double blind trial. With local

ethics approval 120 ASA 1 or 2 patients undergoing GA for elective surgery

were recruited. Group L lidocaine 40mg and venous tourniquet for

30 sec, Group M MgSO4 2.5mmols, Group S 5 mls Saline. Pain on

injection of study drug and propofol were measured with modified verbal rat-

ing score. Data were analysed with Students t-test, Kruskal-Wallis ANOVA

on ranks and Mann-Whitney rank sum test.

Results: Groups were similar in age, weight, and sex.

Table 1. Pain scores after injection of propofol.

Pain score 0 N (%) 1 N (%) 2 N (%) 3 N (%)

Group S (n 40) 17 (42.5) 15 (37.5) 7 (17.5) 1 (2.5)

Group L* (n 40) 24 (60) 6 (15) 7 (17.5) 3 (7.5)

Group M (n 40) 33 (82.5) 5 (12.5) 2 (5) 0 (0)

*The difference in pain scores between Group L and Group S did not reach statistical

significance. The distribution of pain scores was significantly different between Group

M and Group S (p 0.05) and Group M and Group L (p 0.05). If you consider pain on

injection of study drug and propofol combined, for Group M and Group L, the difference

seen in Table 1 is no longer sign ificant (p 0.84).

Conclusions: In this study MgSO4 2.5 mmols given before IV propofol is

more effective than either lidocaine or saline in preventing pain on injection

of propofol. However pain on injection of the MgSO4 itself may limit its clini-

cal usefulness.

References:1 Tan CH, Onsiong MK.Anaesthesia 1998; 53:468476.

2 Picard P, Tramer MR.Anesth Analg 2000; 09:963969.

3 Memis D, Turan A, Maramanlioglu B et al.Anesth Analg 2002; 95:606608.

A-543

Pain on propofol injection: comparison of a reformulated

propofol emulsion to standard propofol with premixed

lidocaine

S. Adam, J. van Bommel, M. Pelka, M. Dirckx, D. Jonsson, J. Klein

Department of Anesthesiology, Erasmus MC, Rotterdam, The Netherlands

Background and Goal of Study: The most commonly used method to

reduce pain on injection is premixture of propofol with lidocaine (1).

Recently, a reformulated lipid emulsion of propofol containing medium-

chain triglycerides (MCT) and long-chain triglycerides (LCT) in equal pro-

portions was found to cause less pain on injection than standard propofol

LCT (2). The goal of this study was to investigate whether propofol MCT/LCTcaused less pain on injection than propofol LCT with premixed lidocaine.

Materials and Methods: In a randomised, prospective, controlled, double-

blinded study, 222 surgical patients received either propofol MCT/LCT

(Group M, n 109) or standard propofol LCT with premixed lidocaine (20 mg

in 200mg propofol) (Group L, n 113). Pain scores were assessed using a

Verbal Analogue Scale (VAS) ranging from 010. Post-operatively, patients

were asked to what extent (VAS 010) they recalled pain on injection.

Results and Discussions: Group L was found to have significantly less

pain on propofol injection (mean VAS 2.5 0.3) than Group M (mean VAS

3.8 0.3), *P 0.002. Also did patients in Group L recall significantly less

pain on injection than Group M (see Figure 1).

Figure 1. VAS of pain on injection and recall of pain; Group M: propofol MCT/LCT, Group

L: propofol LCT with premixed lidocaine. Data: mean SEM, * P 0.05.

Conclusion: Premixing 20mg of lidocaine to 200 mg of standard propofol

LCT causes less pain on injection than propofol MCT/LCT without any addi-

tion of lidocaine.

References:1 Tan C.H.Anaesthesia 1998; 53: 46876.

2 Rau J.Anesth Analg 2001; 93: 3824.

A-544

The prevention of pain from injection of propofol by

dexmedetomidine and comparison with lidocaineA. Turan, D. Memis, G. Kaya, B. Karamanloglu, Z. Pamukcu

Department of Anaesthesiology, Trakya Univ. Medical Faculty,

Edirne, Turkey

Background and Goal of Study: Dexmedetomidine is a 2-adrenoreceptor

agonist with supraspinal, spinal, and peripheral actions. The2 receptors are

located on blood vessels where they inhibit nor epinephrine release. Several

studies have determined lidocaine as the drug most efficiently diminishing

and eliminating pain from propofol injection. We have conducted our study,

to determine the efficacy of dexmedetomidine and compare it with lidocaine

in decreasing pain due to injection of propofol.

Materials and Methods: Following ethic committee approval and written

informed consent, 90 patients were randomly divided into three groups. The

patients were then taken into the operation room where at the dorsum of

both hands were catheterized with a 20 G catheter and the mean arterial

pressure, oxygen saturation, and heart rate were monitored. With the aim of

keeping the drug within the vein, the forearm was squeezed with a tourni-

quet up to 70 mmHg; the patients were administered; saline (5 mL) in Group I

(n 30), 0.25g/kg dexmedetomidine in Group II (n 30), 0.5mg/kg lido-

caine in Group III (n 30), diluted into a 5mL with saline at ambient operat-

ing rooms temperature (2022C). After 20 seconds occlusion was released,

5 mL propofol was administered at a rate of 20 mg in 5 s by a mechanical

syringe. The patients were asked if they had pain in the arm and the

response was assessed. The patients were asked a standard question about

the comfort of the injection, the verbal response and behavioral signs, such

as facial grimacing, arm withdrawal, or tears were noted.

Results and Discussions: Patients with no pain are 4,20,23 according to

groups respectively. Light pain was seen in 5,9,6 according to groups

respectively. Moderate pain was seen in 9,1,1 according to groups respec-

tively. Severe pain was seen in only in 12 patients of Group I. Correlation

determined with log linear analysis, significant difference were found pain

score 0 in group I (p 0.05).

Conclusion(s): As a result; this is the first clinical study showing that thedexmedetomidine may be useful in prevention of propofol injection pain.

When compared with lidocaine, dexmedetomidine was equally effective in

reducing the pain associated with the i.v. injection of propofol.

A-545

Development of acute tolerance to the EEG effect of

propofol in rats

M. Schywalsky, H. Ihmsen, A. Tzabazis, H. Schwilden

Department of Anaesthesiology, University of Erlangen-Nuremberg,

Erlangen, Germany

Background and Goal of Study: Previous studies with propofol in rats

suggested development of acute tolerance to the EEG effect (1). The aim of

this study was to evaluate acute tolerance by means of EEG controlled

closed loop anaesthesia as this approach allows precise determination ofdrug requirement to maintain a defined drug effect.

Materials and Methods: Two days before starting the experiments ten male

Sprague-Dawley rats (402 40 g bw, mean SD) were anaesthetized with

ketamine (76 7 mg ip) and a jugular vein catheter was placed for drug infu-

sion. The catheter was tunneled under the pelt and externalized on the dor-

sal surface of the neck. At the day of experiment rats were anaesthetized with

propofol, the femoral artery was catheterized and needle electrodes were

placed occipito-occipitally for EEG recording. Subsequently, closed loop

control of propofol was started. The median frequency (MEF) of the EEG

power spectrum was used as pharmacodynamic control parameter. Infusion

rate was controlled by a model based adaptive algorithm to maintain a set-

point of MEF 3 0.5Hz for 90 min. The performance of the feedback sys-

tem was characterized by the prediction error PE (MEF-setpoint)/setpoint.

Propofol plasma concentrations were determined from arterial samples by

HPLC and tested for differences using the t-test for paired samples.

Results and Discussions: The chosen setpoint was successfully main-

tained in all rats. The median and the absolute median value of PE

Experience and recall of pain on injection

0

1

2

3

4

5

injection recall

Verbalanalogue

scale

(VAS

)

Group M (MCT/LCT) Group L (LCT lidocaine)

*

*

*

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