Assessment and modification of pain on induction with propofol (Diprivan)

Characteristics that increase the risk for pain on propofol injection

BACKGROUND

Propofol for anesthesia has become increasingly popular for endoscopic procedures. However, pain on propofol injection (POPI) remains an issue with administration. The primary endpoint of this study was to identify patient characteristics and factors, such as IV site and gauge, that could predict the occurrence of POPI.

METHODS

This was a prospective chart review study of 291 patients undergoing endoscopic procedures. The patient's demographics, intravenous (IV) site, and gauge were extrapolated. POPI was scored 0-3: 0 for no pain, 1 for minimal discomfort or awareness of sensation, 2 for discomfort but manageable/tolerable, and 3 for severe discomfort with writhing.

RESULTS

291 patient charts were reviewed. One patient was excluded for a lower extremity IV site. 225 (77.6%) had no pain, 48 (16.6%) grade 1 pain, 16 (5.5%) grade 2 pain, and 1 (0.3%) grade 3 pain. 137, 13, and 140 patients respectively had antecubital (AC), forearm, and hand IVs. Zero patients with an AC IV experienced a score greater than 1. Compared to AC, forearm IVs with pain of 2-3 had a univariate odds ratio (OR) of 11.3 (0.66,1.92; p-value < 0.001), and hand IVs had a univariate OR of 18.8 (2.46,143.3; p-value < 0.001) with a multivariable OR 15.2 (1.93,118.9; p-value 0.004). Patients with anxiety/depression and pain had a univariate OR 2.31 (1.09, 7.27; p-value 0.031) with a multivariable OR 2.85 (1.06, 7.74; p-value 0.039). SSRI/SNRI use had a univariate OR 1.56 (0.57,4.28; p-value 0.38). Alcohol use had a univariate OR 1.24 (0.39,3.91; p-value 0.71). Narcotic use had a Univariate OR 6.18 (1.49,25.6; p-value 0.012). Diabetic patients had a univariate OR of 1.42 (0.45,4.48; p-value 0.55). Chronic pain had a univariate OR of 3.11 (1.04,9.28; p-value 0.042). Females had a univariate OR 0.98 (0.37,2.63; p-value 0.95).

CONCLUSION

This study identified potential characteristics for having POPI. The incidence of POPI was statistically significant in patients with hand and forearm IVs compared to AC IV sites, larger IV gauges, history of depression/anxiety, history of chronic narcotic use, fibromyalgia, and chronic pain syndromes. This shows the potential of premedicating with analgesics or using AC sites on these select patients to help reduce the risk of POPI.

Micro-Solvation of Propofol in Propylene Glycol-Water Binary Mixtures: Molecular Dynamics Simulation Studies

The water microstructure around propofol plays a crucial role in controlling their solubility in the binary mixture. The unusual nature of such a water microstructure can influence both translational and reorientational dynamics, as well as the water hydrogen bond network near propofol. We have carried out all-atom molecular dynamics simulations of five different compositions of the propylene glycol (PG)/water binary mixture containing propofol (PFL) molecules to investigate the differential behavior of water microsolvation shells around propofol, which is likely to control the propofol solubility. It is evident from the simulation snapshots for various compositions that the PG at high molecular ratio favors the water cluster and extended chainlike network that percolates within the PG matrix, where the propofol is in the dispersed state. We estimated that the radial distribution function indicates higher ordered water microstructure around propofol for high PG content, as compared to the lower PG content in the PG/water mixture. So, the hydrophilic PG regulates the stability of the water micronetwork around propofol and its solubility in the binary mixture. We observed that the translational and rotational mobility of water belonging to the propofol microsolvation shell is hindered for high PG content and relaxed toward the low PG molecular ratio in the PG/water mixture. It has been noticed that the structural relaxation of the hydrogen bond formed between the propofol and the water molecules present in the propofol microsolvation shell for all five compositions is found to be slower for high PG content and becomes faster on the way to low PG content in the mixture. Simultaneously, we calculated the intermittent residence time correlation function of the water molecules belonging to the microsolvation shell around the propofol for five different compositions and found a faster short time decay followed up with long time components. Again, the origin of such long time decay is primarily from the structural relaxation of the microsolvation shell around the propofol, where the high PG content shows the slower structural relaxation that turns faster as the PG content approaches to the other end of the compositions. So, our studies showed that the slower structural relaxation of the microsolvation shell around propofol for a high PG molecular ratio in the PG/water mixture correlate well with the extensive ordering of the water microstructure and restricted water mobility and facilitates the dissolution process of propofol in the binary mixture.

Effect of ondansetron compared to lidocaine and placebo for reducing propofol injection pain: A systematic review and meta-analysis of randomized controlled trials

OBJECTIVE

Propofol is the most commonly used intravenous anesthetic medication and is most commonly associated with post-operative pain. Several drugs are investigated to reduce post-operative pain caused by propofol injection. Ondansetron is a potent anti-emetic drug showing promising results as an analgesic. This meta-analysis aims to compare the efficacy of ondansetron to placebo and lidocaine in reducing post-operative pain caused by propofol injection.

METHODS

PubMed, Embase, Cochrane Library, Web of Science, and Scopus were searched for relevant randomized controlled trials (RCTs) till May 2022. We conducted a meta-analysis using RevMan software version 5.4, and we assessed the quality of included RCTs using the Cochrane risk of bias tool.

RESULTS

In our study, we included 23 RCTs with 2957 participants. Compared to placebo, ondansetron significantly increased the rate of no pain [risk ratio (RR) = 2.36, 95% confidence interval (CI) (1.39-4.01)], and reduced moderate [RR = 0.39, 95% CI (0.30-0.52)] and severe pain [RR = 0.34, 95% CI (0.24-0.50)]. Furthermore, ondansetron significantly reduced PONV [RR = 0.73, 95% CI (0.58, 0.91)]. On the other hand, ondansetron showed an inferior efficacy to lidocaine regarding the incidence of no, moderate, and severe pain.

CONCLUSION

Ondansetron is effective in reducing post-operative propofol-induced pain. However, lidocaine is more effective than it.

The safety and efficacy of remimazolam tosylate combined with propofol in upper gastrointestinal endoscopy: A multicenter, randomized clinical trial

INTRODUCTION

Hypotension is the most common adverse event under propofol-mediated sedation and is possible to cause varying degrees of damage to patients. Whereas remimazolam has a poorer sedative effect than propofol.

AIM

The aim of this study was to explore the advantages of the combination of remimazolam tosylate and propofol.

METHODS

304 patients were divided into the remimazolam tosylate group (RT group), the propofol group (P group), and the remimazolam tosylate plus propofol group(R+T group). The primary outcome was the incidence of hypotension. Secondary outcomes included the results of sedation and recovery. The safety results mainly include the incidence of Hypotension, adverse respiratory events, postoperative nausea and vomiting, hiccup, cough, body movement and bradycardia.

RESULTS

The incidence of hypotension was 56.7% in the P group, 12.6% in the RT group, and 31.3% in the R+P group, three groups of pairwise comparisons showed statistical differences, with P< 0.001. The incidence of body movement was significantly higher in the RT group (26.1%) than in the P group (10.3%) and the R+P group (12.5%), P = 0.004. The endoscopist satisfaction was higher in the P (3.87±0.44) and R+P (3.95±0.22)groups than in the RT(3.53±0.84) group. The incidence of adverse events, in descending order, was P group, RT group, and R+P group (93.8%vs.61.3%vs.42.7%).

CONCLUSION

Co-administration had fewer adverse events than propofol monotherapy, also had a better sedative effect and higher endoscopist satisfaction than remimazolam monotherapy.

TRIAL REGISTRATION

Clinical trial registration number: NCT05429086.

Efficacy of Pre-Treatment with Remimazolam on Prevention of Propofol-Induced Injection Pain in Patients Undergoing Abortion or Curettage: A Prospective, Double-Blinded, Randomized and Placebo-Controlled Clinical Trial

Background

Propofol-induced injection pain (PIP) is a well-known problem in general anesthesia. We hypothesized that pre-treatment with remimazolam prevents PIP in patients undergoing abortion or curettage.

Materials and Methods

In this prospective, single-center, double-blinded, randomized, placebo-controlled clinical trial, adult patients aged 18 to 60 undergoing abortion or curettage were randomly assigned to three groups. Group Lido received system lidocaine (a bolus of 0.5 mg kg⁻¹, iv). Group Remi received remimazolam (a bolus of 0.1 mg kg⁻¹, iv). Group NS received identical volumes of 0.9% normal saline. Sixty seconds after the injection of lidocaine, remimazolam or saline, patients were injected with propofol at a rate of 12 mL/min until the loss of consciousness. The primary outcome was the incidence of PIP at the time of induction using 4-point scale. Secondary outcomes included propofol-induced injection pain, vital signs, the characteristics of anesthesia and surgery, and adverse events.

Results

The incidence of patients with PIP was higher in group NS than that in group Lido and group Remi (75.7, 44.3, and 42.9%, respectively, p < 0.001). The percentages of patients with moderate PIP were higher in group NS than that in group Lido and group Remi (20.0, 2.9, and 1.4%, respectively, p < 0.001). Moreover, the consumption of propofol and the incidence of adverse event (hypoxemia and chin lifting) in group Remi were lower than that in group NS and Lido, and less patients got physical movement and cough in group Remi. The recovery time in group NS was longer than that in group Lido and Remi.

Conclusion

Our findings indicate that pre-treatment with remimazolam reduced the incidence and intensity of PIP in abortion or curettage patients, equivalent to that of lidocaine without severe adverse effects.

Trial Registration

Chinese Clinical Trial Registry (identifier: ChiCTR2100041805).

Comparison Between Intravenous Nalbuphine and Lidocaine in Reducing Propofol-Induced Injection Pain During Gastroscopy: A Randomized Controlled Trial

Introduction

Intravenous propofol anesthesia is widely used in painless endoscopy. However, propofol injection pain is a common adverse effect. This study investigated the effects of nalbuphine and lidocaine in reducing propofol-induced injection pain.

Methods

In this double-blind, randomized study, 330 patients were randomly divided into three groups by using a random number table: the nalbuphine group (N), lidocaine group (L), and control group (C). The N, L, and C groups received either 0.1 mg/kg nalbuphine, 0.5 mg/kg lidocaine, or an equivalent volume of normal saline, respectively, as pretreatment drug. Then propofol was manually injected. The primary outcome of this study was the incidence of propofol-induced injection pain, and secondary outcomes included the severity of propofol-induced injection pain, vital signs, and adverse events, including hypotension, bradycardia (< 50 beats/min), hypoxemia (SpO₂ < 90%), drowsiness, physical movement, and cough.

Results

The percentages of patients with propofol injection pain were higher in group C than in group N and group L (64, 34, and 27%, respectively, p < 0.05). The percentage of patients with severe pain after propofol injection was significantly higher in group C than in group N and group L (12, 1, and 0%, respectively, p < 0.05). The doses of propofol in group C and group L were significantly higher than that in group N. More patients suffered hypoxemia in group N than in group C and group L. Then, less patients got physical movement and cough in group N.

Conclusions

Pretreatment with nalbuphine 0.1 mg/kg was effective in reducing propofol-induced injection pain and propofol consumption. Propofol combined with nalbuphine can be safely and effectively used during gastroscopy.

Trial Registration

Chinese Clinical Trial Registry; ChiCTR1900025438.

Premedication with oral paracetamol for reduction of propofol injection pain: a randomized placebo-controlled trial

Background

To compare the effect of premedication with 2 different doses of oral paracetamol to prevent pain at propofol intravenous injection.

Methods

We conducted a double-blind randomized controlled trial in which patients scheduled for induction of general anesthesia with intravenous propofol received either a placebo, 500 mg or 1000 mg of oral paracetamol (P500 and P1000, respectively) 1 h prior to induction. Two mg/kg of propofol was injected at a rate of 600 ml/hr. After 1/4 of the full dose had been injected, the syringe pump was paused, and patients were asked to rate pain at the injection site using a verbal numerical rating score (VNRS) from 0 to 10.

Results

Three hundred and twenty-four patients were included. Pain intensity was lower in both P500 and P1000 groups (median VNRS [interquartile range] = 2 [0–3] and 4 [2–5], respectively) than in the placebo group (8 [7–10]; P < 0.001)*. The rate of pain was lower in the P1000 group (70.4%) than in both the P500 and the placebo group (86.1 and 99.1%, respectively; P < 0.001)*. The respective rates of mild (VNRS 1–3), moderate (VNRS 4–6) and severe pain (VNRS 7–10) were 47.2, 23.2 and 0% in the P1000 group, 28.7, 50 and 7.4% in the P500 group, and 0, 22.2 and 76.9% in the placebo group (P < 0.001* for between group comparisons). Tolerance was similar in the 3 groups.

Conclusions

A premedication with oral paracetamol can dose-dependently reduce pain at propofol intravenous injection. To avoid this common uncomfortable concern for the patients, this well-tolerated, available and cheap treatment appears as an option to be implemented in the current practice.

Trial registration

TCTR20150224002. Prospectively registered on 24 February 2015.

Pain during Injection of Propofol: The Effect of Prior Administration of Ephedrine

Propofol causes pain on intravenous injection in 28 to 90% of patients. A number of techniques have been tried to minimize propofol-induced pain, with variable results. In a randomized, double-blind, placebo-controlled trial, we compared the efficacy of ephedrine 30 μg/kg pretreatment to lignocaine 40 mg for prevention of propofol-induced pain. Ninety-three adult patients, ASA 1 and 2, undergoing elective laparoscopic cholecystectomy were randomly assigned to three groups of 31 each. Group 1 received normal saline, group 2 received lignocaine 2% (40 mg) and group 3 received 30 μg/kg ephedrine. All pretreatment drugs were made up to 2 ml. Pain at the time of propofol injection was assessed on a four-point scale: 0=no pain, 1=mild pain, 2=moderate pain, and 3=severe pain. Twenty-seven patients (87%) of ephedrine pretreatment patients had pain during intravenous injection of propofol as compared to 24 (77%) in the normal saline group. In the lignocaine group, propofol-induced pain was observed in only 13 (42%) when compared with other study groups (P<0.05). Pretreatment with ephedrine 30 μg/kg did not attenuate pain associated with intravenous injection of propofol, nor did it improve haemodynamic stability during induction. However, pretreatment with 2% lignocaine (40 mg) was effective in attenuating propofol-associated pain.

Preventing Pain on Injection of Propofol: A Comparison between Lignocaine Pre-treatment and Lignocaine Added to Propofol

A randomized double-blind study compared two methods of preventing the pain from injection of propofol, lignocaine pre-treatment followed by propofol and lignocaine added to propofol. One hundred patients received a 4 ml solution intravenously with a venous tourniquet for 1 minute, followed by propofol mixed with 2 ml of solution. Patients were divided into two treatment groups of 50 patients each: 4 ml 1% lignocaine pre-treatment followed by propofol and 2 ml saline, or 4 ml saline followed by propofol and 2 ml 2% lignocaine. Pain was assessed with a 100 mm visual analogue scale after induction and in recovery. The incidence of injection pain was 8% in the propofol mixed with lignocaine group, and 28% in the lignocaine pre-treatment group. This difference is statistically significant (P=0.017). For those patients who had pain, the mean pain score was 26.5 on induction for the propofol with lignocaine group (n=4), while the mean score was 44.4 for the pre-treatment group (n=13). The difference was not statistically significant (P=0.25). None of the propofol mixed with lignocaine group recalled pain, while 13 of the pre-treatment group did so. Lignocaine pre-treatment does not improve the immediate or the recalled comfort of patients during propofol induction when compared to lignocaine added to propofol. It is recommended that lignocaine should be added to propofol for induction rather than given before induction.

Lidocaine for reducing propofol-induced pain on induction of anaesthesia in adults

BACKGROUND

Pain on propofol injection is an untoward effect and this condition can reduce patient satisfaction. Intravenous lidocaine injection has been commonly used to attenuate pain on propofol injection. Although many studies have reported that lidocaine was effective in reducing the incidence and severity of pain, nevertheless, no systematic review focusing on lidocaine for preventing high-intensity pain has been published.

OBJECTIVES

The objective of this review was to determine the efficacy and adverse effects of lidocaine in preventing high-intensity pain on propofol injection.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL; 2014, Issue 10), Ovid MEDLINE (1950 To October 2014), Ovid EMBASE (1988 to October 2014), LILACS (1992 to October 2014) and searched reference lists of articles.We reran the search in November 2015. We found 11potential studies of interest, those studies were added to the list of 'Studies awaiting classification' and will be fully incorporated into the formal review findings when we update the review.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) using intravenous lidocaine injection as an intervention to decrease pain on propofol injection in adults. We excluded studies without a placebo or control group.

DATA COLLECTION AND ANALYSIS

We collected selected studies with relevant criteria. We identified risk of bias in five domains according to the following criteria: random sequence generation, allocation concealment, adequacy of blinding, completeness of outcome data and selective reporting. We performed meta-analysis by direct comparisons of intervention versus control. We estimated the summary odds ratios (ORs) and 95% confidence intervals using the random-effects Mantel-Haenszel method in RevMan 5.3. We used the I(2) statistic to assess statistical heterogeneity. We assessed overall quality of evidence using the GRADE approach.

MAIN RESULTS

We included 87 studies, 84 of which (10,460 participants) were eligible for quantitative analysis in the review. All participants, aged 13 years to 89 years, were American Society of Anesthesiologists (ASA) I-III patients undergoing elective surgery. Each study was conducted in a single centre in high- , middle- and low-income countries worldwide. According to the risk of bias assessment, all except five studies were identified as being of satisfactory methodological quality, allowing 84 studies to be combined in the meta-analysis. Five of the 84 studies were assessed as high risk of bias: one for participant and personnel blinding, one for incomplete outcome data, and three for other potential sources of bias.The overall incidence of pain and high-intensity pain following propofol injection in the control group were 64% (95% CI 60% to 67.9%) and 38.1% (95% CI 33.4% to 43.1%), respectively while those in the lidocaine group were 30.2% (95% CI 26.7% to 33.7%) and 11.8% (95% CI 9.7% to 13.8%). Both lidocaine admixture and pretreatment were effective in reducing pain on propofol injection (lidocaine admixture OR 0.19, 95% CI 0.15 to 0.25, 31 studies, 4927 participants, high-quality evidence; lidocaine pretreatment OR 0.13, 95% CI 0.10 to 0.18, 43 RCTs, 4028 participants, high-quality evidence). Similarly, lidocaine administration could considerably decrease the incidence of pain when premixed with the propofol (OR 0.19, 95% CI 0.15 to 0.24, 36 studies, 5628 participants, high-quality evidence) or pretreated prior to propofol injection (OR 0.14, 95% CI 0.11 to 0.18, 52 studies, 4832 participants, high-quality evidence). Adverse effects of lidocaine administration were rare. Thrombophlebitis was reported in only two studies (OR not estimated, low-quality evidence). No studies reported patient satisfaction.

AUTHORS' CONCLUSIONS

Overall, the quality of the evidence was high. Currently available data from RCTs are sufficient to confirm that both lidocaine admixture and pretreatment were effective in reducing pain on propofol injection. Furthermore, there were no significant differences of effect between the two techniques.

Influence of polyvinyl chloride infusion extension tube on propofol injection pain: a randomised controlled study

BACKGROUND

Propofol injection pain is a common and unsolved anaesthesia problem.

OBJECTIVES

The present study attempted to confirm that the plasticiser di(2-ethylhexyl) phthalate in polyvinyl chloride (PVC) infusion tubes may increase propofol injection pain by increasing the aqueous propofol concentration.

DESIGN

A randomised controlled study.

SETTING

University teaching hospital, 1 April to 25 June 2013.

PATIENTS

One hundred patients scheduled for elective surgery were allocated randomly to the PVC or the control (C) group. The PVC group received a propofol (Diprivan) infusion via a 1-m PVC infusion extension tube, whereas group C received propofol injected directly through the port of the cannula.

INTERVENTION

After the syringe was loaded with propofol, air was expelled from the tube and the syringe was left standing for 5 min; intravenous propofol 0.5 mg kg⁻¹ was then injected either through the PVC tube or directly into the cannula.

MAIN OUTCOME MEASURE

A verbal rating scale was used to evaluate the propofol injection pain in both groups. Di(2-ethylhexyl) phthalate and aqueous propofol concentrations were also measured in samples of propofol after simulated injection. To investigate whether the increase in aqueous propofol concentration was caused by leached di(2-ethylhexyl) phthalate, the same amount of di(2-ethylhexyl) phthalate as that measured in the PVC group was added to the samples (group D).

RESULTS

The incidences of pain in groups PVC and C were 88 and 46%, respectively (P < 0.0001). The di(2-ethylhexyl) phthalate concentration in group PVC (1.01 ± 0.07 μg ml⁻¹) was greater than that in group C (lower than the detection limit of 0.03 μg ml⁻¹). No significant difference was found between the aqueous propofol concentrations in groups PVC (25.9 ± 1.8 μg ml⁻¹) and D (24.4 ± 1.1 μg ml⁻¹) (P = 0.22), which were significantly higher than that in group C (14.3 ± 1.0 μg ml⁻¹) (P = 0.079).

CONCLUSION

Propofol injection pain is increased by contact with PVC infusion tubing as a result of an increase in aqueous propofol concentration caused by di(2-ethylhexyl) phthalate leaching into the lipid emulsion.

TRIAL REGISTRATION

chictr.org identifier: ChiCTR-TRC-12003170.

Propofol: a review of its role in pediatric anesthesia and sedation

Propofol is an intravenous agent used commonly for the induction and maintenance of anesthesia, procedural, and critical care sedation in children. The mechanisms of action on the central nervous system involve interactions at various neurotransmitter receptors, especially the gamma-aminobutyric acid A receptor. Approved for use in the USA by the Food and Drug Administration in 1989, its use for induction of anesthesia in children less than 3 years of age still remains off-label. Despite its wide use in pediatric anesthesia, there is conflicting literature about its safety and serious adverse effects in particular subsets of children. Particularly as children are not "little adults", in this review, we emphasize the maturational aspects of propofol pharmacokinetics. Despite the myriad of propofol pharmacokinetic-pharmacodynamic studies and the ability to use allometrical scaling to smooth out differences due to size and age, there is no optimal model that can be used in target controlled infusion pumps for providing closed loop total intravenous anesthesia in children. As the commercial formulation of propofol is a nutrient-rich emulsion, the risk for bacterial contamination exists despite the Food and Drug Administration mandating addition of antimicrobial preservative, calling for manufacturers' directions to discard open vials after 6 h. While propofol has advantages over inhalation anesthesia such as less postoperative nausea and emergence delirium in children, pain on injection remains a problem even with newer formulations. Propofol is known to depress mitochondrial function by its action as an uncoupling agent in oxidative phosphorylation. This has implications for children with mitochondrial diseases and the occurrence of propofol-related infusion syndrome, a rare but seriously life-threatening complication of propofol. At the time of this review, there is no direct evidence in humans for propofol-induced neurotoxicity to the infant brain; however, current concerns of neuroapoptosis in developing brains induced by propofol persist and continue to be a focus of research.

The Effects of Nitroglycerine on Pain Control During the Propofol Injection; a Controlled, Double-Blinded, Randomized Clinical Trial

Background:

The use of Propofol often results in pain upon injection, which is sometimes very distressing for patients. Many patients report some degree of pain or discomfort on injection with propofol. Injection-induced pain during induction of anesthesia can result in patient's discomfort.

Objectives:

This study was performed to evaluate the effects of nitroglycerine on pain severity in patients undergoing propofol injection.

Patients and Methods:

In this double-blind randomized clinical trial, 100 patients with ASA class I and II undergoing anesthesia with propofol injection were selected for the study from 2012 to 2013 in Imam Reza training hospital. Patients were randomly assigned to case and control groups and received either 20 μg of nitroglycerine or normal saline as placebo. The severity of injection pain was assessed using a four-point scale. An anesthesiologist observed hemodynamic and local adverse effects.

Results:

The pain severity in nitroglycerine group was significantly lower compared with the placebo group (P < 0.0001). Moreover, the local adverse reactions were observed only in three patients in the placebo group while no patient in the drug group experienced adverse effects (P = 0.242). The systolic blood pressure showed no significant difference between two groups before and after the induction of anesthesia but the diastolic blood pressure and the heart rate was significantly different between study groups.

Conclusions:

Nitroglycerine may be a safe and effective adjuvant therapeutic for pain reduction in patients under propofol injection. Hence, its use for reduction of propofol injection-induced pain is recommended.

Pre-treatment with intravenous granisetron to alleviate pain on propofol injection: A double-blind, randomized, controlled trial

Background:

Propofol is one of the widely used intravenous (i.v.) anaesthetics, although pain on injection still remains a considerable concern for the anaesthesiologists. A number of techniques has been tried to minimize propofol-induced pain with variable results. Recently, a 5-HT₃ antagonist, ondansetron pre-treatment, has been shown to reduce propofol-induced pain. The aim of our randomized, placebo-controlled, double-blinded study was to determine whether pre-treatment with intravenous granisetron, which is routinely used in our practice for prophylaxis of post-operative nausea and vomiting, would reduce propofol-induced pain.

Methods:

Eighty-two women, aged 18–50 years, American society of Anaesthesiologist grading (ASA) I–II, scheduled for various surgeries under general anaesthesia were randomly assigned to one of the two groups. One group received 2 mL 0.9% sodium chloride while the other group received 2 mL granisetron (1 mg/mL), and were accompanied by manual venous occlusion for 1 min. Then, 2 mL propofol was injected through the same cannula. Patients were asked by a blinded investigator to score the pain on injection of propofol with a four-point scale: 0=no pain, 1=mild pain, 2=moderate pain, 3=severe pain.

Results:

Twenty-four patients (60%) complained of pain in the group pre-treated with normal saline as compared with six (15%) in the group pre-treated with granisetron. Pain was reduced significantly in the granisetron group (P<0.05). Severity of pain was also lesser in the granisetron group compared with the placebo group (2.5% vs. 37.5%).

Conclusion:

We conclude that pre-treatment with granisetron along with venous occlusion for 1 min for prevention of propofol-induced pain was highly successful.

Reduction of Propofol-Induced Pain through Pretreatment with Lidocaine and/or Flurbiprofen

OBJECTIVE

Pain is a well recognised complication of propofol injection. The purpose of this study was to compare the efficacy of flurbiprofen, lidocaine and a combination of the two in reducing pain on injection of propofol.

DESIGN

Prospective, randomised, double-blind, placebo-controlled study.

SETTING

University hospital in Tsukuba City, Japan.

PATIENTS AND INTERVENTIONS

120 patients, 56 males and 64 females, aged 20-66 years, scheduled for elective plastic surgery were included. Patients received intravenously either lidocaine 20mg, flurbiprofen 50mg, both, or placebo (saline) accompanied by manual venous occlusion for 2 minutes, followed by administration of propofol 2 mg/kg into a dorsal hand vein (n = 30 in each group). A blinded researcher asked each patient to evaluate the pain score (0 = none, 1 = mild, 2 = moderate, 3 = severe) during propofol injection.

MAIN OUTCOME MEASURES AND RESULTS

The incidence and intensity of pain was less in patients receiving lidocaine (27%, pain score 0 [median]), flurbiprofen (43%, 0), or both (3%, 0) along with venous occlusion than in those receiving placebo (90%, 2) along with venous occlusion (p < 0.01). Combined lidocaine and flurbiprofen with venous occlusion was the most effective treatment (p < 0.05). No complications such as pain, oedema, wheal or flare response were observed at the injection sites within the first 24 hours after surgery.

CONCLUSION

Combined lidocaine 20mg and flurbiprofen 50mg along with venous occlusion for 2 minutes was very effective for reducing pain on injection of propofol in patients scheduled for elective plastic surgery.

Comparative study of attenuation of the pain caused by propofol intravenous injection, by granisetron, magnesium sulfate and nitroglycerine

Background:

Propofol has the disadvantage of causing pain or discomfort on injection. The aim of the study was to assess the efficacy of pretreatment with various drugs to alleviate the propofol injection pain.

Methods:

One hundred American Society of Anesthesiology (ASA) I and II adults, scheduled for various elective surgical procedures under general anesthesia (GA), were included in the study. They were randomly divided into four groups having 25 patients in each group. Group A received pretreatment with intravenous (i.v.) magnesium sulfate, group B received i.v. granisetron, group C received i.v. nitroglycerine and group D was the control group. One-fourth of the total calculated induction dose of propofol was administered over a period of 5 seconds. The patients were asked about the pain on injection. The intensity of pain was assessed using verbal response. A score of 0–3 which corresponds to no, mild, moderate and severe pain was recorded.

Results:

All the three drugs reduced the incidence and intensity of pain on propofol injection but the order of efficacy in attenuation of pain on the propofol injection was granisetron > nitroglycerine > magnesium sulfate > control.

Conclusion:

Granisetron was the most effective followed by nitroglycerine and magnesium sulfate in attenuating pain on propofol intravenous injection.

Clinical factors affecting the pain on injection of propofol

BACKGROUND

Pain on propofol injection is a well-known adverse effect. We evaluated the clinical factors that affect the pain on injection of propofol to develop a strategy to prevent or reduce pain.

METHODS

We conducted a prospective, observational study of 207 adult patients (ASA I-II), and the patients were classified according to gender, age, the body mass index (BMI), the IV site and the side of the IV site. During the 10 seconds after propofol injection, pain intensity was measured on an 11-point numerical rating scale (0 = no pain and 10 = worst possible pain). Pain in excess of 3 on the numerical scale was regarded as moderate to severe pain.

RESULTS

THE SUBGROUPS OF GENDER (FEMALE: 55.6% vs. male: 25.0%; P < 0.01) and the IV site (dorsum of hand: 61.2% vs. wrist: 40.0% vs. antecubital fossa: 22.5%; P < 0.01) had significantly different frequencies for the incidence of pain on injection on the univariate and multivariate analyses. For the subgroup of females, the incidence of pain was statistically different according to the age group (20-40 yr: 71.0% vs. 41-60: 54.8% vs. 61-80: 38.5%; P = 0.014).

CONCLUSIONS

Our results showed that the younger age patients, the patients with a peripheral IV site and female patients are more sensitive to pain on the injection of propofol.

The effect of pretreatment with two different concentrations of remifentanil on propofol injection pain

BACKGROUND

Propofol produces anesthesia with rapid recovery but also causes pain on injection. This study was designed to evaluate the effects of two different concentrations of remifentanil for minimizing the pain caused by propofol and to compare the hemodynamic changes during propofol-remifentanil infusion.

METHODS

In a randomized, double-blind study of 80 patients, we compared the severity of the injection pain of propofol between two groups of patients. The initial effect-site target concentration of remifentanil was set at 4 ng/ml (the R4 group, n = 40) or 8 ng/ml (the R8 group, n = 40). After the effect-site concentration of remifentanil was achieved, the infusion of propofol was started with the concentration of 4 microgram/ml. The remifentanil-related complications were evaluated and the severity of the pain caused by propofol was compared by using a four-point scale during the propofol infusion. The heart rate and arterial blood pressure were measured at pre-induction, just before intubation and at 1 minute after intubation.

RESULTS

The severity of injection pain of propofol was significantly lower in the R8 group than in the R4. There was no significant difference in the incidence of remifentanil-related complications between the two groups. Compared with the pre-induction values, the heart rate and arterial blood pressure were significantly lower at pre-intubation and at 1 minute after intubation in the R4 and R8 groups.

CONCLUSIONS

Pretreatment with an effect-site concentration of 8 ng/ml remifentanil may be useful for minimizing the propofol injection pain compared with 4 ng/ml remifentanil.

Increased phosphorylation of extracellular signal-regulated kinase in trigeminal nociceptive neurons following propofol administration in rats

Although propofol (PRO) is widely used in clinic as a hypnotic agent, the underlying mechanisms of its action on pain pathways is still unknown. Sprague-Dawley rats were assigned to receive PRO or pentobarbital (PEN) and were divided into 2 groups as LIGHT and DEEP hypnotic levels based on the EEG analysis. Rats in each hypnotic level received capsaicin injection into the face and phosphorylated extracellular signal-regulated kinase (pERK) immunohistochemistry was performed in subnucleus caudalis (Vc) and upper cervical spinal cord. In the rats with PEN or PRO administration, a large number of pERK-like immunoreactive (LI) cells was observed in the trigeminal spinal subnuclei interpolaris and caudalis transition zone (Vi/Vc), middle Vc, and transition zone between Vc and upper cervical spinal cord (Vc/C2) following capsaicin injection into the whisker-pad region. The number of pERK-LI cells in Vi/Vc, middle Vc, and Vc/C2 was significantly larger in rats with PRO infusion than those with PEN infusion. The number of pERK-LI cells was increased following an increase in the dose of PRO but not in PEN. The pERK-LI cells were mainly distributed in the Vi/Vc, middle Vc, and Vc/C2 after the bolus infusion of PRO. The expression of pERK-LI cells was depressed after the intravenous lidocaine application before bolus PRO infusion. The present findings suggest that PRO induced an enhancement of the activity of trigeminal nociceptive pathways through nociceptors innervating the venous structure, as indicated by a lidocaine-sensitive increase in pERK. This may explain deep pain around the injection regions during intravenous bolus infusion of PRO.

PERSPECTIVE

The effect of propofol administration on ERK phosphorylation in the subregions of the spinal trigeminal complex and upper cervical spinal cord neurons were precisely analyzed in rats with PRO infusion. A large number of pERK-LI cells was observed following intravenous PRO administration, suggesting an enhancement of trigeminal nociceptive activity and that PRO may produce pain through nociceptors innervating the venous structures during infusion.

Admixture of ephedrine to offset side effects of propofol: a randomized, controlled trial

STUDY OBJECTIVE

To determine whether adding ephedrine to propofol is as effective as adding lidocaine at reducing injection pain, and its effects on hemodynamics.

DESIGN

Randomized, double-blinded, controlled trial.

SETTING

District general hospital in the United Kingdom.

PATIENTS

156 adult, ASA physical status I, II, and III patients undergoing elective or emergency general anesthesia.

INTERVENTIONS

Patients were randomized to one of three groups to receive one mL of 1% lidocaine per 20 mL of 1% propofol (Group L), 15 mg of ephedrine per 20 mL of propofol (Group E15), or 30 mg of ephedrine per 20 mL of propofol (Group E30).

MEASUREMENTS AND MAIN RESULTS

Pain on injection, heart rate, and blood pressure at one-minute intervals for ten minutes were recorded. There was no significant difference in injection pain among groups. Group E30 had the least amount of hemodynamic change.

CONCLUSION

Adding 30 mg of ephedrine to 20 mL of 1% propofol is as effective as adding lidocaine in preventing injection pain, and it results in a more stable hemodynamic profile.

Pain on injection with microemulsion propofol

AIMS

To evaluate the incidence and severity of injection pain caused by microemulsion propofol and lipid emulsion propofol in relation to plasma bradykinin generation and aqueous free propofol concentrations.

METHODS

Injection pain was evaluated in 147 patients. Aqueous free propofol concentrations in each formulation, and in formulation mixtures containing agents that reduce propofol-induced pain, were measured by high-performance liquid chromatography. Plasma bradykinin concentrations in both formulations and in their components mixed with blood sampled from six volunteers were measured by radioimmunoassays. Injection pain caused by 8% polyethylene glycol 660 hydroxystearate (PEG660 HS) was evaluated in another 10 volunteers.

RESULTS

The incidence of injection pain [visual analogue scale (VAS) >30 mm] caused by microemulsion and lipid emulsion propofol was 69.7 and 42.3% (P < 0.001), respectively. The median VAS scores for microemulsion and lipid emulsion propofol were 59 and 24 mm, respectively (95% confidence interval for the difference 12.5, 40.0). The aqueous free propofol concentration of microemulsion propofol was seven times higher than that of lipid emulsion propofol. Agents that reduce injection pain did not affect aqueous free propofol concentrations. Microemulsion propofol and 8% PEG660 HS enhanced plasma bradykinin generation, whereas lipid emulsion propofol and lipid solvent did not. PEG660 HS did not cause injection pain.

CONCLUSIONS

Higher aqueous free propofol concentrations of microemulsion propofol produce more frequent and severe pain. The plasma kallikrein-kinin system may not be involved, and the agents that reduce injection pain may not act by decreasing aqueous free propofol concentrations.

Influence of aging on lidocaine requirements for pain on injection of propofol

STUDY OBJECTIVE

To evaluate the influence of aging on lidocaine requirements for propofol-induced pain on injection.

DESIGN

Prospective, randomized, double-blind, placebo-controlled study.

SETTING

The study was undertaken at a University hospital.

PATIENTS

160 ASA physical status I and II adult patients scheduled for elective surgery with general anesthesia.

INTERVENTIONS

Patients received placebo (saline) or lidocaine intravenously at three different doses (10, 20, or 40 mg), with venous occlusion for two minutes, followed by injection of propofol 0.5 mg/kg into a dorsal hand vein.

MEASUREMENT AND MAIN RESULTS

Pain during injection of propofol was evaluated. For young patients, the frequency of propofol-induced pain was 70% in patients receiving lidocaine 10 mg (P = not significant); 50% in those receiving lidocaine 20 mg (P = not significant); and 30% in those receiving lidocaine 40 mg (P < 0.05), compared with placebo (80%). For elderly patients, 15 patients (75%) complained of pain in the placebo group, compared with 13 (65%) in the lidocaine 10 mg group (P = not significant); 5 (25%) in the lidocaine 20 mg group (P < 0.05); and 4 (20%) in the lidocaine 40 mg group (P < 0.05).

CONCLUSIONS

A lidocaine dose of 40 mg for young patients and 20 mg for old patients, with venous occlusion for two minutes, is sufficient to reduce pain on injection of propofol.

Influence of age on flurbiprofen axetil requirements for preventing pain on injection of propofol in Japanese adult surgical patients: a prospective, randomized, double-blind, vehicle-controlled, parallel-group, dose-ranging study

BACKGROUND

Pain on injection is a recognized adverse event (AE) of propofol administration for the induction of general anesthesia. Preceded by venous occlusion, flurbiprofen axetil, a prodrug of the NSAID flurbiprofen, has been associated with a reduction in pain induced by propofol injection. A review of the literature determined that no published data were available on the influence of age on the requirements for flurbiprofen axetil dose.

OBJECTIVE

This study was undertaken to examine the influence of age on flurbiprofen axetil requirements for the treatment of propofol-induced pain on injection in Japanese adult surgical patients.

METHODS

This prospective, randomized, double-blind, vehicle-controlled, parallel-group, dose-ranging study was conducted at the Department of Anesthesiology, Institute of Clinical Medicine, University of Tsukuba, Tsukuba, Japan. Young (age 20-40 years) and older (age 60-80 years) Japanese patients scheduled for various types of surgery (eg, cholecystectomy) were eligible. Patients were randomized to receive flurbiprofen axetil at 1 of 2 doses (25 or 50 mg, regardless of body weight) or inactive vehicle (saline), preceded by manual venous occlusion with a rubber tourniquet for 2 minutes and followed by the infusion of the first 25% of calculated propofol dose (0.5 mg/kg at room temperature, 23 degrees C) into the largest dorsal vein of the hand through a 20-G IV cannula (without local anesthesia), followed by the release of the occlusion and delivery of propofol 2 mg/kg. An investigator blinded to treatment questioned each patient about pain intensity during propofol injection which was assessed using a verbal rating scale: 0 = none; 1 = mild; 2 = moderate; and 3 = severe. The overall prevalence of pain was calculated in each group. AEs at the injection site (pain, edema, wheal, inflammation) were assessed by the study investigator for 24 hours after surgery using spontaneous reporting and patient interview.

RESULTS

A total of 150 patients, 75 young adults (38 men, 37 women; mean [SD] age, 31 [5] years; mean [SD] height, 163 [7] cm; mean [SD] body weight, 58 [9] kg) and 75 older adults (38 men, 37 women; mean [SD] age, 70 [6] years; mean [SD] height, 154 [8] cm; mean [SD] body weight, 53 [10] kg), were enrolled. Each treatment group comprised 25 patients. No differences in demographic characteristics were observed among the 3 study groups. In young patients, the overall prevalence of propofol-induced pain was significantly lower in patients who received flurbiprofen axetil 50 mg (12 [48%]) compared with that in patients who received flurbiprofen axetil 25 mg (20 [80%]) or vehicle (22 [88%]) (P < 0.05 and P < 0.01, respectively). The median pain intensity score was significantly lower in patients who received flurbiprofen axetil 50 mg (0) compared with that in patients who received flurbiprofen axetil 25 mg (1) or vehicle (2) (P < 0.05 and P < 0.01, respectively). In older patients, the overall prevalences of pain on propofol injection were 9 (36%) in the flurbiprofen axetil 50-mg group and 11 (44%) in the flurbiprofen axetil 25-mg group compared with 21 (84%) in the vehicle group (both, P < 0.01). The median pain score was significantly lower in patients who received flurbiprofen 50 mg (0) or 25 mg (0) than in those who received vehicle (1) (both, P < 0.01). All treatments were well tolerated.

CONCLUSIONS

In this small clinical trial in Japanese surgical patients undergoing general anesthesia, flurbiprofen axetil requirements for the reduction of pain during injection of propofol were found to be 50 mg in young adults (age 20-40 years) and 25 or 50 mg in older adults (age 60-80 years), regardless of weight, preceded by venous occlusion for 2 minutes.

Modulation of neuronal activity in CNS pain pathways following propofol administration in rats: Fos and EEG analysis

We studied Fos expression in the central nociceptive pathways at different sedative levels in order to clarify the central mechanism of propofol's nociceptive action. Sprague-Dawley rats received propofol (PRO) or pentobarbital (PEN) and were divided into two groups with different doses of drug administration (light and deep sedative levels) based on the electroencephalogram analysis. Rats at each sedative level received heat stimulation to their face and Fos immunohistochemistry was performed at various brain sites. We also infused lidocaine into the jugular vein to test whether PRO directly activated nociceptors distributed in the vein. Fos expression in two major ascending pain pathways (lateral and medial systems) and descending modulatory system were precisely analyzed following intravenous (i.v.) administration of PRO or PEN. Many Fos protein-like immunoreactive (Fos protein-LI) cells were expressed in the trigeminal spinal nucleus caudalis (Vc), parabrachial nucleus, parafascicular nucleus, a wide area of the primary somatosensory cortex, anterior cingulate cortex, amygdala, periaqueductal gray, solitary tract nucleus, and lateral hypothalamus following heating of the face during PRO or PEN infusion. The number of Fos protein-LI cells was significantly greater in many Central nervous system regions during PRO infusion compared with PEN. Fos expression was significantly greater in the Vc and Periaqueductal gray following greater amount of PRO infusions compared, whereas they were significantly smaller in the Vc in the rats with PEN infusion. The Fos expression was significantly depressed following i.v. infusion of lidocaine before PRO administration. The present findings suggest that PRO is involved in the enhancement of Vc activity through direct activation of the primary afferent fibers innervating veins, resulting in pain induction during infusion.

Characteristics of propofol-evoked vascular pain in anaesthetized rats

BACKGROUND

In this study we have assessed vascular pain caused by the i.v. anaesthetic agent, propofol, using the flexor reflex response and compared this with that of capsaicin in anaesthetized intact rats.

METHODS

Experiments were performed on 133 male Sprague-Dawley rats weighing 280-340 g. The animals were anaesthetized with urethane (1.3 g kg(-1), i.p.), and an arterial cannula was inserted to the level of the bifurcation of the femoral artery. The magnitude of the flexor reflex was examined by recording the electromyogram from the posterior biceps femoris/semitendinosus muscles.

RESULTS

Our data show that the flexor reflexes evoked by intra-arterial (i.a.) injection of propofol (1%, 25-100 microl) and capsaicin (0.05-0.2 microg) were dose dependent. An initial i.a. injection of procaine (2%, 200 microl) blocked both responses. Furthermore, the flexor reflex induced by these chemical stimuli were inhibited by morphine (5 mg kg(-1), s.c.) and restored with naloxone (1.5 mg kg(-1), s.c.). Pre-treatment with capsazepine (20 microg, i.a.), a selective VR1 antagonist, inhibited the capsaicin-evoked response, but not that of propofol. Indomethacin (10 mg kg(-1), i.p.), a non-selective cyclo-oxygenase inhibitor, inhibited only the propofol-evoked response and this recovered with arterial PGE2 (5 microg).

CONCLUSIONS

Collectively our data suggest that propofol-evoked vascular pain is mainly initiated by prostanoids.

Less local pain on intravenous infusion of a new propofol emulsion

BACKGROUND

Local pain at the site of intravenous (iv) injection of propofol remains a considerable problem in clinical anaesthesiology, and particularly so in infants. The aim of the present study was to compare the influence of two different emulsions of propofol on local pain following iv administration.

METHODS

Eighty adult patients (ASA I-II) scheduled for ear-nose-throat or plastic surgery were randomly allocated into two study groups: A and B. A 1.0-mm teflon cannula (BD, Helsingborg, Sweden) was inserted into a dorsal vein on each hand. Each patient was given two 3.0-ml iv bolus injections of two different propofol emulsions of 10 mg ml(-1) over 2 s, one in each cannula, at 5-min intervals. The first study drug administered was Diprivan (AstraZeneca, Södertälie, Sweden) in group A (n = 34) and Propofol-Lipuro (Braun, Melsungen, Germany) in group B (n = 39). Each patient was then asked by a blinded investigator to score maximal pain intensity on a visual analogue scale (VAS).

RESULTS

The maximal intensity of propofol-induced local pain was significantly (P < 0.0001) lower after Propofol-Lipuro than after Diprivan--median 1 (25th percentile: 0; 75th percentile: 2) range 0-6 vs. 3 (0; 5) 0-9 VAS units.

CONCLUSION

The considerably lower intensity of local pain found to be associated with iv administration of the new drug formula Propofol-Lipuro indicates that emulsions of propofol based on medium- and long-chain triglycerides have a clinical advantage over traditional ones for induction of anaesthesia.

Vein pretreatment with magnesium sulfate to prevent pain on injection of propofol is not justified

PURPOSE

Propofol produces anesthesia with rapid recovery. However, it causes pain or discomfort on injection. A number of techniques have been tried for minimizing propofol-induced pain with variable results. We have compared the efficacy of magnesium and lidocaine for the prevention of propofol induced pain.

METHODS

Three hundred ASA I and II adults undergoing elective surgery were randomly assigned into three groups of 100 each. Group I received magnesium sulfate 1 g, Group II received lidocaine 2% (40 mg) and Group III received normal saline, all in a volume of 2 mL and accompanied by venous occlusion for one minute. Induction with propofol 2.5 mg.kg(-1) was accomplished following the release of venous occlusion. Pain was assessed on a four-point scale: 0 = no pain, 1 = mild pain, 2 = moderate pain, and 3 = severe pain at the time of pretreatment and propofol injection. Results were analyzed by 'Z' test. A P value of < 0.05 was considered as significant.

RESULTS

Pain during i.v. pretreatment with magnesium was 31% as compared to 2% for both the lidocaine and control groups (P < 0.05). Seventy-six percent of patients in the control group had pain during i.v. propofol as compared to 32% and 42% in the magnesium and the lidocaine groups respectively (P < 0.05). Lidocaine and magnesium pretreatment were equally effective in attenuating pain during the propofol injection (P > 0.05).

CONCLUSIONS

Intravenous magnesium and lidocaine pretreatment are equally effective in attenuating propofol-induced pain. However, magnesium pretreatment itself causes pain. Therefore, there is no justification in the use of magnesium pretreatment for attenuating pain associated with i.v. propofol.

Pain During Injection of Propofol: The Effect of Prior Administration of Butorphanol

Propofol causes pain or discomfort on injection in 28%-90% of patients. A number of techniques have been tried for minimizing propofol-induced pain with variable results. We compared the efficacy of butorphanol and lidocaine for prevention of propofol-induced pain. One-hundred-fifty ASA I-II adults, undergoing elective surgery were randomly assigned into 3 groups of 50 each. Group I (NS) received normal saline, Group II (L) received lidocaine 2% (40 mg), and Group III (B) received butorphanol 2 mg. All patients received pretreatment solutions made in 2 mL with normal saline administered over 5 s. One min after pretreatment patients received one-fourth of the total calculated dose of propofol (2.5 mg/kg) over 5 s. Assessment of pain with IV propofol was done by using a four-point scale: 0 = no pain, 1 = mild pain, 2 = moderate pain and 3 = severe pain at the time of propofol injection. In the control Group 39 (78%) patients had pain during propofol injection as compared to 21 (42%) and 10 (20%) in the lidocaine and butorphanol groups, respectively (P < 0.05). Butorphanol was the most effective. We therefore suggest the IV pretreatment with butorphanol 2 mg for attenuation of pain associated with propofol injection.

Pretreatment with thiopental for prevention of pain associated with propofol injection

Propofol causes pain on IV injection in 28%-90% of patients. A number of techniques have been tried to minimize propofol-induced pain, with variable results. We compared the efficacy of pretreatment with thiopental 0.25 mg/kg and 0.5 mg/kg and lidocaine 40 mg after venous occlusion for prevention of propofol-induced pain. One-hundred-twenty-four adult patients, ASA physical status I-II, undergoing elective surgery were randomly assigned into 4 groups of 31 each. Group I received normal saline, group II received lidocaine 2% (40 mg), and groups III and IV received thiopental 0.25 mg/kg and 0.5 mg/kg, respectively. All pretreatment drugs were made in 2 mL and were accompanied by manual venous occlusion for 1 min. Propofol was administered after release of venous occlusion. Pain was assessed with a four-point scale: 0 = no pain, 1 = mild pain, 2 = moderate pain, and 3 = severe pain at the time of propofol injection. Twenty-four patients (77%) complained of pain in the group pretreated with normal saline as compared with 12 (39%), 10 (32%), and 1 (3%) in the groups pretreated with lidocaine 40 mg, thiopental 0.25 mg/kg, and thiopental 0.5 mg/kg, respectively (P < 0.05). Thiopental 0.5 mg/kg was the most effective treatment. We therefore suggest routine pretreatment with thiopental 0.5 mg/kg along with venous occlusion for 1 min for prevention of pain associated with propofol injection.

IMPLICATIONS

Pain associated with IV injection of propofol is seen in 28%-90% patients. Pretreatment with thiopental 0.25 mg/kg and 0.5 mg/kg after manual venous occlusion for 1 min effectively attenuated pain associated with propofol injection. Thiopental 0.5 mg/kg was the most effective in prevention of propofol pain and can be used routinely.

Propofol and remifentanil for intubation without muscle relaxant: the effect of the order of injection

BACKGROUND

Common practice in intubation without muscle relaxant is to inject the opioid drug prior to the hypnotic drug. Because remifentanil reaches adequate cerebral concentration more rapidly than does propofol, we tested the hypothesis that injection of remifentanil after propofol might lead to better intubating conditions.

METHODS

Thirty ASA I-II patients scheduled for elective surgery and with no anticipated difficult intubation were enrolled in the study. Five minutes after midazolam 30 microg kg(-1), patients were randomized into two groups: group PR received propofol 2.5 mg kg(-1) followed by remifentanil 1 microg kg(-1), and group RP received remifentanil 1 microg kg(-1) followed by propofol 2.5 mg kg(-1). Intubating conditions were compared using a well-validated score, and continuous arterial pressure was recorded non-invasively.

RESULTS

Compared with group RP, intubating conditions were significantly better in group PR. The mean arterial pressure decrease was more pronounced in group RP.

CONCLUSIONS

We therefore conclude that in premedicated healthy patients with no anticipated risk of difficult intubation, intubating and haemodynamic conditions are better when remifentanil is injected after propofol.

Pain on injection of propofol: comparison of metoprolol with lidocaine

BACKGROUND AND OBJECTIVE

Pain is often experienced when propofol is injected, and intravenous lidocaine is often effective in preventing such pain. We decided to determine whether metoprolol, given before the injection of propofol, is as effective as lidocaine in reducing the incidence and severity of the pain.

METHODS

Ninety patients scheduled for elective surgery under general anaesthesia were randomly allocated to one of three groups to receive either metoprolol 2 mg, lidocaine 20 mg or saline 2 mL before any propofol was injected. Each patient was given one of these agents intravenously via a 20-G cannula on the dorsum of the hand whilst the venous drainage was occluded manually, at the middle of the forearm, for 45 s. After the occlusion was released, propofol 2.0-2.5 mg kg(-1), at room temperature, was injected at 2 mL (20 mg) every 4 s. Pain was assessed verbally and scored as none (0), mild (1) or severe (2).

RESULTS

The incidence of severe pain in the control group (56.7%) was significantly higher than in the metoprolol and lidocaine groups (16.6 and 10%, respectively). The number of patients who were free of pain was significantly higher in those who had been given either metoprolol or lidocaine.

CONCLUSIONS

Pretreatment with intravenous metoprolol was equally as effective as lidocaine in reducing the pain associated with propofol injection.

Effect of sevoflurane on human neutrophil apoptosis

BACKGROUND AND OBJECTIVE

Both chronic occupational exposure to volatile anaesthetic agents and acute in vitro exposure of neutrophils to isoflurane have been shown to inhibit the rate of apoptosis of human neutrophils. It is possible that inhibition of neutrophil apoptosis arises through delaying mitochondrial membrane potential collapse. We assessed mitochondrial depolarization and apoptosis in unexposed neutrophils and neutrophils exposed to sevoflurane in vivo.

METHODS

A total of 20 mL venous blood was withdrawn pre- and postinduction of anaesthesia, the neutrophils isolated and maintained in culture. At 1, 12 and 24 h in culture, the percentage of neutrophil apoptosis was assessed by dual staining with annexin V-FITC and propidium iodide. Mitochondrial depolarization was measured using the dual emission styryl dye JC-1.

RESULTS

Apoptosis was significantly inhibited in neutrophils exposed to sevoflurane in vivo at 24 (exposed: 38 (12)% versus control: 28 (11)%, P = 0.001), but not at 1 or 12 h, in culture. Mitochondrial depolarization was not delayed in neutrophils exposed to sevoflurane.

CONCLUSIONS

The most important findings are that sevoflurane inhibits neutrophil apoptosis in vivo and that inhibition is not mediated primarily by an effect on mitochondrial depolarization.

Opioid-induced respiratory depression is associated with increased tidal volume variability

BACKGROUND AND OBJECTIVE

mu-agonistic opioids cause concentration-dependent hypoventilation and increased irregularity of breathing. The aim was to quantify opioid-induced irregularity of breathing and to investigate its time-course during and after an opioid infusion, and its ability to predict the severity of respiratory depression.

METHODS

Twenty-three patients breathing spontaneously via a continuous positive airway pressure (CPAP) mask received an intravenous (i.v.) infusion of alfentanil (2.3 microg kg(-1) min(-1), 14 patients) or pirinitramide (piritramide) (17.9 microg kg(-1) min(-1), nine patients) until either a cumulative dose of 70 microg kg(-1) for alfentanil or 500 microg kg(-1) for pirinitramide had been achieved or the infusion had to be stopped for safety reasons. Tidal volumes (VT) and minute ventilation were measured with an anaesthesia workstation. For every 20 breaths, the quartile coefficient was calculated (Qeff20V(T)).

RESULTS

Both the decrease of minute volume and the increase of Qeff20V(T) during and after opioid infusion were highly significant (P < 0.001, ANOVA). Patients in which the alfentanil infusion had to be terminated prematurely had lower minute volumes (P = 0.002, t-test) and higher Qeff20V(T) (P = 0.034, t-test) than those who received the complete dose. Changes in the regularity of breathing measured as Qeff20V(T) parallel those of minute ventilation during and after opioid infusion.

CONCLUSIONS

Opioids cause a more complicated disturbance of the control of respiration than a mere resetting to higher PCO2. Furthermore, Qeff20V(T) appears to predict the severity of opioid-induced respiratory depression.

Intravenous patient-controlled analgesia after thoracotomy: a comparison of morphine with tramadol

BACKGROUND AND OBJECTIVE

This study examined the quality of analgesia together with the side-effects produced by tramadol compared with morphine using intravenous patient-controlled analgesia during the first 24 h after thoracotomy.

METHODS

Forty-four patients scheduled for thoracotomy were included in the study. Morphine 0.3 mg kg(-1) was given interpleurally 20 min before a standard general anaesthetic. In the postanaesthetic care unit, the patients were randomly allocated to one of two groups to self-administer tramadol or morphine using a patient-controlled analgesia device throughout a 24 h period. The patient-controlled analgesia device was programmed to deliver tramadol 20 mg as an intravenous bolus or morphine 2 mg with a lockout time of 10 min.

RESULTS

Mean cumulative morphine and tramadol consumption were 48.13 +/- 30.23 and 493.5 +/- 191.5 mg, respectively. There was no difference in the quality of analgesia between groups. Five (26.3%) patients in the tramadol group and seven (33%) in the morphine group had nausea, and three of the latter patients vomited. The incidence rate of vomiting with tramadol was 5.2%. All vital signs were within safe ranges. Sedation was less in the tramadol group, but not statistically significant.

CONCLUSIONS

In this clinical setting, which includes interpleural morphine pre-emptively, postoperative analgesia provided by tramadol was similar to that of morphine at rest and during deep inspiration. Side-effects were slight and comparable between the patients receiving morphine and tramadol.

Effects of ropivacaine on human neutrophil function: comparison with bupivacaine and lidocaine

BACKGROUND AND OBJECTIVE

Neutrophils are important both for the immunological defence system and for the inflammatory tissue autoinjury mechanism. However, many local anaesthetics impair certain neutrophil functions. The aim was to assess the effects of ropivacaine, bupivacaine and lidocaine on human neutrophils from adult volunteers.

METHODS

Chemotaxis, phagocytosis, reactive oxygen species production, intracellular calcium ion ([Ca2+]i) concentrations and protein kinase C activity were measured in the absence and presence of ropivacaine, bupivacaine or lidocaine. The lowest concentrations of the local anaesthetics were similar to those clinically observed in the plasma.

RESULTS

Bupivacaine did not affect any neutrophil function (P > 0.05). Ropivacaine failed to change chemotaxis or phagocytosis, while lidocaine suppressed both these neutrophil functions. Ropivacaine (15, 150 microg mL(-1)) and lidocaine (20, 200 microg mL(-1)) impaired neutrophil production of O2-, H2O2 and OH- (P < 0.05) at similar rates (by 7-10%). These same concentrations of ropivacaine and lidocaine suppressed [Ca2+1i elevation. Finally, neither ropivacaine nor bupivacaine inhibited protein kinase C activity, while lidocaine did.

CONCLUSIONS

Suppression of the [Ca2+]i response in neutrophils by ropivacaine may represent one of the mechanisms responsible for the impairment of neutrophil functions. It should be emphasized that the inhibitory effects of ropivacaine are minor and are attained only at high concentrations, which may minimize the clinical implication of ropivacaine-associated impairment of reactive oxygen species production. Further studies using in vivo systems are required to identify the inhibitory effects of ropivacaine on reactive oxygen species production in clinical settings.

Neural nets and prediction of the recovery rate from neuromuscular block

BACKGROUND AND OBJECTIVE

The aim was to train artificial neural nets to predict the recovery of a neuromuscular block during general anaesthesia. It was assumed that the initial/early neuromuscular recovery data with the simultaneously measured physical variables as inputs into a well-trained back-propagation neural net would enable the net to predict a rough estimate of the remaining recovery time.

METHODS

Spontaneous recovery from neuromuscular block (electrically evoked electromyographic train-of-four responses) were recorded with the following variables known to affect the block: multiple minimum alveolar concentration, end-tidal CO2 concentration, and peripheral and central temperature.

RESULTS

The mean prediction errors, mean absolute prediction errors, root-mean-squared prediction errors and correlation coefficients of all the nets were significantly better than those of average-based predictions used in the study. The root-mean-squared prediction error of the net - employing minimum alveolar concentrations from the whole recovery period (the recovery time from E2/E1 = 0.30 to E4/E1 = 0.75; E1 = first response of train-of-four, E2 = second response of train-of-four, etc.)--were significantly smaller than those of other nets, or the same net employing minimum alveolar concentrations only from the initial recovery period (from E2/E1 = 0.30 to E4/E1 = 0.25).

CONCLUSIONS

Neural nets could predict individual recovery times from the neuromuscular block significantly better than the average-based method used here, which was supposed to be more accurate than guesses by any clinician. The minimum alveolar concentration was the only monitored variable that influenced the recovery rate, but it did not aid neural net prediction.

Sevoflurane but not isoflurane can reduce prostacyclin production of endothelial cells

BACKGROUND AND OBJECTIVE

Little is known about the interaction of newer volatile anaesthetics with endothelial eicosanoid production. Sevoflurane may possibly reduce prostacyclin formation. Thus, we compared the influences of sevoflurane and isoflurane on endothelial prostacyclin production.

METHODS

Production of prostacyclin of human umbilical vein endothelial cells was measured by the ELISA technique under basal conditions and after stimulation with calcium ionophore A 23187 10 micromol or histamine 0.1 micromol in the absence and presence of 1 and 2 minimal alveolar concentrations (MAC) of sevoflurane or isoflurane.

RESULTS

The basal production of prostacyclin was unaffected by the volatile anaesthetics. Stimulation of endothelial cells increased prostacyclin formation 3-5-fold. Sevoflurane at 2 MAC, but not at 1 MAC, could reduce stimulated prostacyclin production by about half (P < 0.05). Isoflurane had no inhibitory effect. Inhibition of cyclo-oxygenase function by acetylsalicylic acid abolished the induced burst of prostacyclin formation completely.

CONCLUSIONS

Sevoflurane, but not isoflurane, can reduce stimulated endothelial prostacyclin production in a concentration-dependent manner. Because at least 2 MAC of sevoflurane were required, this effect should be of minor importance under clinical conditions of balanced anaesthesia.

Adsorption of sufentanil to epidural filters and catheters

BACKGROUND AND OBJECTIVE

Stable drug concentrations must be administered to provide adequate patient-controlled epidural analgesia. This study investigated the stability of sufentanil after the epidural delivery system had been flushed with solutions containing the drug.

METHODS

Sufentanil citrate, 5 microg mL(-1) was injected through an epidural catheter system into a glass container. The concentrations of the drug leaving the system, in 1 mL aliquots (1-5 mL) were measured using high-performance liquid chromatography. In the same manner, sufentanil samples were analysed after flushing the filter, as well as after priming the filter and catheter.

RESULTS

ANOVA for repeated measurements demonstrated that sufentanil concentrations remained constant as long as the catheter had been adequately flushed. However, the concentration of sufentanil in the solution exiting the filter was reduced significantly. Hardly any sufentanil could be detected (0.09 +/- 0.01 microg mL(-1), P < 0.001) in the first 1 mL aliquot (probe) leaving the filter. Altogether, 3 mL sufentanil solution was needed to pass through the filter before the baseline values were restored (P > 0.05). The greatest decrease occurred when the whole epidural delivery apparatus (catheter and filter) was primed; to regain baseline values, as much as 4 mL solution was needed to flush the system.

CONCLUSIONS

Sufentanil citrate is adsorbed by the materials used to manufacture systems (catheters, filters) used in epidural anaesthesia. Hence, the epidural catheter system should be primed with sufentanil before connecting it to the patient so as to deliver reliable concentrations.

Nitrous oxide/oxygen mixture and the prevention of pain during injection of propofol

BACKGROUND AND OBJECTIVE

The incidence of pain associated with the injection of propofol still remains a problem. This study sought to examine the analgesic effects of inhaled nitrous oxide in oxygen on the prevention of propofol injection pain.

METHODS

Nitrous oxide in oxygen was compared with a lidocaine (20 mg)-propofol mixture and with propofol alone (control) in a prospective, randomized, observer-blinded study. ASA I and II patients (n = 135) scheduled for elective surgical procedures were studied. A standard propofol injection technique and scoring system to measure the pain on injection was used.

RESULTS

Demographic variables were similar between the study groups. Without analgesia (control) 26 of 45 patients (58%) reported pain on injection compared with 11 of 45 patients (24%) in both the nitrous oxide (95% CI: 14-52%, P = 0.001) and lidocaine groups (95% CI: 14-52%, P = 0.001).

CONCLUSIONS

The inhalation of a nitrous oxide/oxygen mixture significantly reduces the incidence of pain during propofol injection. This therapeutic stratagem was as effective as a lidocaine-propofol mixture.

Effects of repeated anaesthesia on central cholinergic function in the rat cerebral cortex

BACKGROUND AND OBJECTIVE

General anaesthesia may contribute to postoperative cognitive decline in the elderly. The aim was to determine the effects of repeated pentobarbital anaesthesia throughout life on central cholinergic function in the rat.

METHODS

Young Lewis rats were randomly allocated to two groups. The anaesthesia group (n = 15) was anaesthetized with pentobarbital 20 mg kg(-1) intraperitoneally at 6, 8.5, 11, 13.5, 16, 18.5, 21 and 23.5 months of age. The control group (n = 12) was treated identically, apart from the anaesthesia. At 26 months of age, the animals were killed and the brain dissected and stored for analysis. Central cholinergic function in the cortex and hippocampus was assessed by measuring [3H]-epibatidine and [125I]alpha-bungarotoxin binding to nicotinic receptors and choline acetyltransferase (ChAT) activity.

RESULTS

Tissue from nine rats in the anaesthesia group and eight in the control group was available for analysis. There was a significant reduction in alpha-bungarotoxin binding in the anaesthetized compared with the control group in the superior cortex (P < 0.0002) and molecular cortex (P < 0.04). There were no significant differences between the groups for epibatidine binding or ChAT.

CONCLUSIONS

Repeated anaesthesia in rat reduces central nicotinic cholinergic binding in the cortex. The findings may have implications for postoperative cognitive function studies.

Induced arterial hypotension for interventional thoracic aortic stent-graft placement: impact on intracranial haemodynamics and cognitive function

BACKGROUND AND OBJECTIVE

The study investigated the impact of induced arterial hypotension for the facilitation of endovascular stent-graft placement in patients with thoracic aortic aneurysm on cerebral blood flow velocity and neurological/neurocognitive outcome.

METHODS

In 27 ASA III patients, cerebral blood flow velocity was recorded during induced arterial hypotension for endovascular stent-graft placement using transcranial Doppler sonography and the Folstein Mini Mental State Examination and the National Institute of Health Stroke Scale were performed before and after the intervention.

RESULTS

Mean arterial pressure was decreased <50 mmHg, and in 22 patients it was <40 mmHg. Diastolic cerebral blood flow velocity decreased by 59%. Postoperatively, six of 21 patients exhibited changes in the Folstein Mini Mental State Examination and four of these six patients in the National Institute of Health Stroke Scale as indices of new-found neurocognitive dysfunction, but there were no signs of stroke. Loss of the diastolic blood flow profile was detected in two of six patients with new-found neurocognitive dysfunctions and in 18 of 21 patients with no new-found neurocognitive dysfunction. Changes in the Folstein Mini Mental State Examination on postoperative day 1 were correlated to the pre-procedural Folstein Mini Mental State Examination, but not to the time spent with a mean arterial pressure <50 mmHg, <40 mmHg or with a loss of diastolic blood flow profile.

CONCLUSIONS

Transcranial Doppler sonography visualizes the individual effect of induced hypotension and the period of intracranial circulatory arrest during aortic stent-graft placement. However, transient new-found neurocognitive dysfunctions occur independently of the transcranial Doppler data, and are in close correlation to the neurocognitive state before the procedure. The results suggest that induced arterial hypotension is not the major factor for postoperative new-found neurocognitive dysfunction.

Gastric mucosal-to-end-tidal PCO2 difference during major abdominal surgery: influence of the arterial-to-end-tidal PCO2 difference?

BACKGROUND AND OBJECTIVE

Because gastric mucosal PCO2 must be referenced to arterial values via a gastric-to-arterial PCO2 gap (Pg-aCO2), the gastric-to-end-tidal PCO2 difference (Pg-ETCO2) may be proposed as a surrogate method to monitor Pg-aCO2. However, the influence of arterial-to-end-tidal PCO2 (Pa-ETCO2) on its value remains unknown. Pa-ETCO2 may be enhanced by a low cardiac output and subsequent reduced perfusion of the lungs. This study was designed to compare such gaps observed during abdominal surgery in patients with or without preoperative cardiac dysfunction.

METHODS

Haemodynamic, metabolic and tonometric variables were measured in seven patients with Crohn's disease and in five patients with chronic heart failure scheduled for abdominal surgery. Data were collected before skin incision (T0); at extractor placement (T1), 30 (T2) and 60 (T3) min later; at organ extraction (T4), 30 (T5) and 60 (T6) min later, and at the end of surgery (T7).

RESULTS

Gradients appeared larger in the cardiac group. The difference was significant for Pg-ETCO2 during the whole study period, while it was only reached at T1-T2 for Pa-ETCO2 and at T5-T6 for Pg-aCO2. Gaps did not change significantly over the peroperative time points in either group. No major haemodynamic variations were registered in either group.

CONCLUSIONS

In patients with preoperative chronic heart failure, Pg-ETCO2 remained constant throughout a major general surgical procedure and was only moderately influenced by the Pa-ETCO2 gap. In these patients, Pg-ETCO2 may be used as a reliable index of gastrointestinal perfusion after control of PaCO2.

Ondansetron disintegrating tablets of 8 mg twice a day for 3 days did not reduce the incidence of nausea or vomiting after laparoscopic surgery

BACKGROUND AND OBJECTIVE

Although many antiemetic drugs are available for intravenous use in the hospital setting, few are available after patient discharge. Consequently, nausea and vomiting are frequent complaints from patients at home after ambulatory surgery. We tested the hypothesis that the new 8 mg ondansetron disintegrating tablets will decrease the rate of nausea and vomiting at home after laparoscopic surgery.

METHODS

Ninety-six patients were studied in a randomized double-blind study. Starting the first evening after operation and continuing every 12 h for 3 days, patients received either placebo or ondansetron 8 mg disintegrating tablets orally. The patients returned a questionnaire about postoperative nausea and vomiting, other side-effects, e.g. dizziness, headache, nightmare, anxiety and pain, as well as their overall satisfaction at 24 and 72 h after completion of surgery.

RESULTS

The rates of nausea and vomiting were similar in the two groups, both during the first 24 h (28 versus 48%, placebo and ondansetron, respectively (ns) and during the 24-72 h (21 versus 35% (ns)). The incidence rate of vomiting was 8% (placebo) versus 12% (ondansetron) during the first 24 h (ns) and 9 versus 13% respectively in the 24-72 h (ns). No difference between groups was observed in overall satisfaction, incidence of postoperative pain or other side-effects.

CONCLUSIONS

The use of ondansetron disintegrating tablets of 8 mg twice a day for 3 days did not reduce the incidence of nausea and vomiting in patients undergoing outpatient laparoscopic surgery.