The effect of carrier intravenous fluid speed on the injection pain of propofol
Journal
Anesthesia and Analgesia
Journal Volume
81
Journal Issue
5
Pages
1087-1088
Date Issued
1995
Author(s)
Abstract
Pain is a common side effect during propofol injection [1]. Pain intensity can be reduced by injecting the drug into a larger vein in the antecubital fossa [1,2] or by diluting it with Intralipid or 5% dextrose [3,4]. Nevertheless, injection into a fast-flowing intravenous infusion did not have the expected effect [5,6]. Moreover, it is reported that increasing diluent flow increases the pain associated with injection. There is less pain when the carrier intravenous (IV) fluid is stopped completely and only undiluted propofol is infused [7]. Since this finding has not been proved, we designed this randomized, double-blind study to investigate whether the speed of carrier IV fluid would influence the intensity of pain. Methods This study was approved by our local hospital ethics committee. One hundred fifty women (ASA grade I or II) scheduled for elective gynecologic surgery were studied after they had given informed, written consent. Patients with allergy or seizure history were excluded. All patients were unpremedicated. A 20-gauge cannula was inserted at the distal side of the cephalic vein near the wrist for IV infusion. Normal saline, 6 mL, was given at a speed of 1200 mL/h to test the quality of the IV route. Patients without pain on injection were assigned randomly to one of three groups, each with 50 patients. All patients received propofol at a speed of 400 mL/h and the speeds of carrier IV (normal saline) for Group A, B, and C were 0, 400, and 800 mL/h, respectively. All speeds were controlled by Terumo syringe pump (STC-523). After 2 mL of propofol was injected at the speed of 400 mL/h, the score of injection pain was assessed by a nurse who was blinded to the protocol of this study. The grading criteria was as follows: 0, no pain experienced; 1, patients complained of mild pain or soreness; 2, moderate pain complaint by patients; 3, severe pain associated with grimacing, withdrawal movement of forearm, or both. After pain grading, a full dose of propofol was given and anesthesia was continued as usual. One-way analysis of variance was used for comparison of ages. The pain scores were analyzed by Kruskal-Wallis one-way analysis of variance and Mann-Whitney U-test. P < 0.05 was considered significant. Results Mean (SD) ages among the groups were not significantly different (30 +/- 5, 29 +/- 4, and 30 +/- 6 yr, respectively). Complications such as persistent pain, redness, swelling, and thrombophlebitis were not found in any patients. The pain scores of Group C were significantly higher than those of Group A or B Table 1. The pain intensities in Group B patients were more severe than those in Group A patients, but not statistically significant.Table 1: Pain Scores During Injection of PropofolDiscussion Owing to the nearly normal osmolality and pH of propofol [1,8], the infrequent occurrence of thrombophlebitis [2,4,9], and the wide range of pain response between animal species [5], the mechanism of pain on propofol injection is thought to be related to the pain mediators such as kininogen activated after exposure of the vein wall to propofol, but not a direct irritant effect [4,5]. In this study, we found that the faster the carrier IV infusion, the more severe the pain with the propofol injection. This phenomenon may be explained by fewer kininogen molecules produced from the smaller contact area between the drug and vein endothelium due to the smaller volume of carrier IV fluid given [7]. From another point of view, we assumed that when the carrier fluid was completely stopped, propofol would be diluted by the venous blood; but when the speed of carrier IV fluid was rapid, the dilution effect of venous blood might be decreased by the large amount of IV fluid injected, and propofol was diluted mostly by the aqueous solution. The intensity of pain after IV propofol injection is related to its free aqueous concentration [3]. Consequently, we hypothesized that the propofol diluted in the aqueous solution might be more painful than that in the blood with the same concentration. Awake and oriented patients were needed to accurately assess pain intensity. Two mL of propofol was given in this study to keep patients from becoming drowsy. To avoid possible bias, we administered propofol by syringe pump at a standardized rate. Thus, injection pain was evaluated at the same dose and infusion rate. The incidence and intensity of pain increases after slow injection of propofol [5]. It is possible that when the carrier IV fluid is stopped completely, a higher propofol injection rate further decreases the intensity of pain. Lidocaine mixed with propofol reduces pain intensity [10]. However, the mixture should be used within 30 min to ensure a stable emulsion [10]. Injecting propofol into a large vein or refrigerating propofol to 4 degrees C is not always possible in clinical practice [11]. Stopping the IV fluid completely was a simple and safe method to alleviate pain. We conclude that injection of propofol into a vein with no associated fluid flowing through it reduces the incidence and severity of pain caused by propofol.
SDGs
Other Subjects
kininogen; lidocaine; propofol; anesthesia induction; article; clinical feature; disease association; edema; female; human; incidence; intravenous administration; major clinical study; pain; priority journal; statistical analysis; thrombophlebitis; Analysis of Variance; Anesthetics, Intravenous; Female; Human; Pain; Propofol; Time Factors
Type
journal article