Prevention of Pain on Injection with Propofol: A Quantitative Systematic Review

The Impact of Excluding Trials from Network Meta-Analyses - An Empirical Study

Network meta-analysis (NMA) expands the scope of a conventional pairwise meta-analysis to simultaneously compare multiple treatments, which has an inherent appeal for clinicians, patients, and policy decision makers. Two recent reports have shown that the impact of excluding a treatment on NMAs can be substantial. However, no one has assessed the impact of excluding a trial from NMAs, which is important because many NMAs selectively include trials in the analysis. This article empirically examines the impact of trial exclusion using both the arm-based (AB) and contrast-based (CB) approaches, by reanalyzing 20 published NMAs involving 725 randomized controlled trials and 449,325 patients. For the population-averaged absolute risk estimates using the AB approach, the average fold changes across all networks ranged from 1.004 (with standard deviation 0.004) to 1.072 (with standard deviation 0.184); while the maximal fold changes ranged from 1.032 to 2.349. In 12 out of 20 NMAs, a 1.20-fold or larger change is observed in at least one of the population-averaged absolute risk estimates. In addition, while excluding a trial can substantially change the estimated relative effects (e.g., log odds ratios), there is no systematic difference in terms of changes between the two approaches. Changes in treatment rankings are observed in 7 networks and changes in inconsistency are observed in 3 networks. We do not observe correlations between changes in treatment effects, treatment rankings and inconsistency. Finally, we recommend rigorous inclusion and exclusion criteria, logical study selection process, and reasonable network geometry to ensure robustness and generalizability of the results of NMAs.

Comparative study between 2 different doses of pregabalin and lidocaine on pain following propofol injection: A double-blind, randomized clinical consort study

BACKGROUND

Propofol, an intravenous anesthetic, often causes pain on injection, which can be very distressful to patients. We investigated the analgesic effect of pregabalin on pain following propofol injection, compared with lidocaine.

METHODS

In a randomized, double-blind, prospective trial, 120 patients were randomized into 3 groups of 40 each; who received oral placebo and intravenous lidocaine 40 mg with venous occlusion for 1 minute (group L, n = 40), oral pregabalin 75 mg and intravenous normal saline with venous occlusion for 1 minute (group LP, n = 40), and oral pregabalin 150 mg and intravenous normal saline with venous occlusion for 1 minute (group HP, n = 40) as pretreatment, followed by administration of 1% propofol 0.5 mg/kg. Pain intensity was measured on a 4-point scale (0 = no, 1 = mild, 2 = moderate, and 3 = severe pain). Any side effects associated with pretreatment substances were recorded during the first 24 hours after surgery.

RESULTS

A total of 120 patients completed this trial. Demographic data were similar between groups. The incidence of pain following propofol injection was significantly reduced in group HP (50%) and group L (55%) compared with group LP (92.5%) (P < 0.05, respectively). The incidences of moderate pain in group HP (12.5%) and group L (15%) were significantly decreased compared with group LP (37.5%; both, P < 0.05). There were no significant differences in the incidence of side effects such as headache and dizziness between groups.

CONCLUSION

Pretreatment with oral pregabalin 150 mg and intravenous lidocaine 40 mg with venous occlusion equally reduced pain from propofol injection.

Heated carrier fluids in decreasing propofol injection pain: a randomized, controlled trial

Background

Propofol is a commonly used intravenous drug during anesthetic induction because of its rapid onset and short duration. However, the injection pain that patients experience is so severe that they recall the induction of anesthesia as the most painful part of the perioperative period. Therefore, the objective of this study was to determine the effect of heated carrier fluids (40℃) in decreasing propofol injection pain.

Methods

A randomized, controlled clinical trial was conducted in 90 patients aged 18 to 65 who were scheduled for either elective or urgent surgery under general anesthesia classified as American Society of Anesthesiologists physical status I or II. Patients were allocated into the following 3 groups: 1) Group W (n = 30) who received 200 ml of heated carrier fluids for 20 minutes prior to propofol injection; 2) Group L (n = 30) who received 200 ml of heated carrier fluids for 20 minutes prior to 0.5 mg/kg 1%lidocaine 1 minute before propofol injection; 3) Group C (control group, n = 30) who received 200 ml of room temperature fluids prior to propofol injection. Pain was evaluated using verbal pain score (VPS).

Results

Group W and Group L showed significant reduction (P = 0.001) in the incidence and severity of injection pain compared to Group C. VPS scores were significantly lower in Group W and Group L compared to those of Group C. Incidence of propofol injection pain was statistically different between Group W (P = 0.005) and Group L (P = 0.037) compared to Group C, but not statistically different between Group W and Group L (P = 0.432).

Conclusions

Both sole injection of heated carrier fluids and the combination of 0.5 mg/kg 1%lidocaine pretreatment effectively reduced propofol injection pain.

Sensitivity to Excluding Treatments in Network Meta-analysis

Network meta-analysis of randomized controlled trials is increasingly used to combine both direct evidence comparing treatments within trials and indirect evidence comparing treatments across different trials. When the outcome is binary, the commonly used contrast-based network meta-analysis methods focus on relative treatment effects such as odds ratios comparing two treatments. As shown in a recent report, when using contrast-based network meta-analysis, the impact of excluding a treatment in the network can be substantial, suggesting a methodological limitation. In addition, relative treatment effects are sometimes not sufficient for patients to make decisions. For example, it can be challenging for patients to trade off efficacy and safety for two drugs if they only know the relative effects, not the absolute effects. A recently proposed arm-based network meta-analysis, based on a missing-data framework, provides an alternative approach. It focuses on estimating population-averaged treatment-specific absolute effects. This article examines the influence of treatment exclusion empirically using 14 published network meta-analyses, for both arm- and contrast-based approaches. The difference between these two approaches is substantial, and it is almost entirely due to single-arm trials. When a treatment is removed from a contrast-based network meta-analysis, it is necessary to exclude other treatments in two-arm studies that investigated the excluded treatment; such exclusions are not necessary in arm-based network meta-analysis, leading to substantial gain in performance.

Comparison of the effects of lidocaine pre-administration and local warming of the intravenous access site on propofol injection pain: Randomized, double-blind controlled trial

BACKGROUND

Lidocaine reduces pain that occurs upon the intravenous injection of propofol. But, there are few non-pharmacological nursing interventions to reduce propofol injection pain.

OBJECTIVE

To compare the effects of lidocaine pre-administration and local warming of the intravenous access site on propofol injection pain.

DESIGN

Prospective, double-blind, randomized controlled trial.

SETTING

The 555 bed, non-teaching National Cancer Center in Kyunggido, South Korea.

PARTICIPANTS

A total of 96 patients who underwent thyroidectomy under total intravenous general anesthesia with propofol were randomly allocated to the control, lidocaine pre-administration (LA) or local warming (LW) group.

METHODS

All three groups received 2% propofol with an effect-site target at 3μg/mL for induction dose. The control group received 2% propofol with no intervention. The lidocaine pre-administration group received 2% propofol 30s after 1% lidocaine 30mg. The local warming group received 2% propofol after warming of the intravenous access site for 1min using 43°C forced air. Propofol injection pain was assessed by four-point verbal categorial scoring (VCS), numerical rating scale (NRS) and surgical pleth index (SPI).

RESULTS

Pain VCS of the LA group (mean±SD, 1.11±0.45) was significantly reduced (U=-3.92, p<.001) compared to the control group (mean±SD, 1.71±0.74). Pain VCS of the LW group (mean±SD, 0.76±0.44) was significantly reduced (U=-5.17, p<.001) compared to the control group (mean±SD, 1.71±0.74). Pain VCS of the LW group was significantly reduced compared to the LA group (U=-3.33, p=.001]. Pain NRS of the LA group (mean±SD, 4.31±2.32) was significantly reduced (mean difference, 1.82; 95% CI, 0.63-3.00; p=.003) compared to the control group (mean±SD, 6.13±2.39). Pain NRS of the LW group (mean±SD, 3.06±2.37) was significantly reduced (mean difference, 3.07; 95% CI, 1.63-4.51; p<.009) compared to the control group. There were significant differences in pain NRS between the LA group and the LW group (mean difference, 1.25; 95% CI, 0.09-2.42; p=.035). SPI of the LA group (mean±SD, 64.1±16.3) was significantly reduced (mean difference control versus LA, 8.36; 95% CI, 1.64-15.1; p=.016) compared to the control group (mean±SD, 72.5±9.56). SPI of the LW group (mean±SD, 55.0±16.2) was significantly reduced (mean difference control versus LW, 17.4; 95% CI, 10.8-24.0; p<.001) compared to the control group. There was a significant difference in SPI between the LA group and LW group (mean difference, 9.06; 95% CI, 1.02-17.1; p=.028).

CONCLUSION

Local warming of the intravenous access site by 43°C forced air for 1min is slightly more effective in reducing propofol injection pain compared to lidocaine pre-administration.

Etomidate exposure in early infant mice (P10) does not induce apoptosis or affect behaviour

BACKGROUND

Numerous animal studies have shown that all commonly used intravenous anaesthetic drugs and volatile agents may cause neuronal apoptosis following exposure in early life. Most studies have focussed on detecting increased apoptosis but their methods are not always readily transferrable to humans. The lipid formulation of etomidate represents an alternative to the currently established intravenous anaesthetic agents but there is no animal or human data on apoptosis or long-term behavioural changes. The aim of our study was to investigate the effects of etomidate on cerebral neuronal apoptosis and long-term behavioural effects using an established mouse model that represents the clinically relevant period of anaesthesia during early infancy in humans.

METHODS

Six groups of 10 day old mice (P10) were injected with either etomidate 0.3, 3 or 10 mg/kg, propofol 60 mg/kg, ketamine 50 mg/kg or placebo only. Apoptosis in the cerebral cortex and hippocampus was assessed 24 h after treatment (activated caspase-3). Late behavioural effects were tested at 2 months of age (spontaneous activity in a new environment).

RESULTS

No evidence was found of differences in activated caspase 3-concentrations among the study groups. Significant late behavioural changes were only observed in the ketamine group.

CONCLUSION

A single dose of etomidate in early infant mice at P10 did not produce evidence of cerebral apoptosis or impaired adult motor behaviour.

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.

Effects of a fentanyl-propofol mixture on propofol injection pain: a randomized clinical trial

BACKGROUND

Propofol injection pain is a common problem that can be very distressing for patients. We compared the effects of injection with saline followed by injection with a fentanyl-propofol mixture, injection with fentanyl followed by a propofol injection, and injection with saline followed by propofol alone on propofol injection pain.

METHODS

The patients were assigned randomly to one of three groups. A rubber tourniquet was placed on the forearm to produce venous occlusion for 1 min. Before anesthesia induction, group C (control, n = 50) and group M (fentanylpropofol mixture, n = 50) received 5 ml of isotonic saline, while group F (fentanyl, n = 50) received 2 µg/kg of fentanyl. After the tourniquet was released, groups C and F received 5 ml of propofol and group M received 5 ml of a mixture containing 20 ml of propofol and 4 ml of fentanyl. At 10 s after the study drugs were given, a standard question about the comfort of the injection was asked of the patient. We used a verbal rating scale to evaluate propofol injection pain. Statistical analyses were performed with Student's t-tests and Fisher's exact tests; P < 0.05 was considered to indicate statistical significance.

RESULTS

The demographic data were similar among the groups. In group M, the number of patients reporting propofol injection pain was significantly lower than in groups F and C (both P < 0.001). No patient in group F or M experienced severe pain, whereas 24 patients (48%) had severe pain in group C (both P < 0.001).

CONCLUSIONS

This study shows that a fentanyl-propofol mixture was more effective than fentanyl pretreatment or a placebo in preventing propofol injection pain.

Options and Considerations for Procedural Sedation in Pediatric Imaging

As pediatric imaging capabilities have increased in scope, so have the complexities of providing procedural sedation in this environment. While efforts by many organizations have dramatically increased the safety of pediatric procedural sedation in general, radiology sedation creates several special challenges for the sedation provider. These challenges require implementation of additional safeguards to promote safety during sedation while maintaining effective and efficient care. Multiple agent options are available, and decisions regarding which agent(s) to use should be determined by both patient needs (i.e., developmental capacities, underlying health status, and previous experiences) and procedural needs (i.e., duration, need for immobility, and invasiveness). Increasingly, combinations of agents to either achieve the conditions required or mitigate/counterbalance adverse effects of single agents are being utilized with success. To continue to provide effective imaging sedation, it is incumbent on sedation providers to maintain familiarity with continuing evolutions within radiology environments, as well as comfort and competence with multiple sedation agents/regimens. This review discusses the challenges associated with radiology sedation and outlines various available agent options and combinations, with the intent of facilitating appropriate matching of agent(s) with patient and procedural needs.

Ketamine-Propofol Versus Propofol Alone for Procedural Sedation in the Emergency Department: A Systematic Review and Meta-analysis

OBJECTIVES

Propofol is an agent commonly used for procedural sedation and analgesia (PSA) in the emergency department (ED), but it can cause respiratory depression and hypotension. The combination of ketamine-propofol (K-P) is an alternative that theoretically provides a reduction in adverse events compared to propofol. The primary objective of this review was to determine if K-P has a lower frequency of adverse respiratory events in patients undergoing PSA in the ED than propofol alone. Secondary objectives were to compare the proportion of overall adverse events, sedation time, procedure time, and recovery time between K-P and propofol.

METHODS

Electronic searches of Medline, EMBASE, Cochrane Central Register of Controlled Trials, and CINAHL were conducted and reference lists were hand-searched. Randomized controlled trials (RCTs) published in English comparing the use of K-P to propofol alone for PSA in the ED were included.

RESULTS

Six RCTs were included with a combined total of 932 patients (K-P = 520, propofol = 412). Five RCTs reported the proportion of adverse respiratory events; the pooled estimate revealed fewer adverse respiratory events with K-P compared to propofol (29.0% vs. 35.4%; risk ratio [RR] = 0.82; 95% confidence interval [CI] = 0.68 to 0.99). There was no significant difference with respect to the proportion of overall adverse events (38.8% vs. 42.5%; RR = 0.88; 95% CI = 0.75 to 1.04). Procedure time was similar when the groups were compared.

CONCLUSIONS

The premise of combining ketamine with propofol is based on the many synergies that theoretically exist between these two agents. In this study, K-P had a lower frequency of adverse respiratory events in patients undergoing PSA in the ED compared to propofol alone.

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.

Is propofol an optimal agent for procedural sedation and rapid sequence intubation in the emergency department?

Objective:

We conducted a qualitative systematic review to evaluate the efficacy and safety of propofol for direct current cardioversion (DCC), rapid sequence intubation (RSI) and procedural sedation in adult emergency department (ED) patients.

Data source:

MEDLINE (1966 to September 2000), PubMed (to September 2000), EMBASE (1988 to September 2000), Database of Systematic Reviews (to September 2000), Best Evidence (1991 to September 2000) and Current Contents (1996 to September 2000) databases.

Study selection:

English-language, randomized, comparative evaluations of propofol for procedures routinely conducted in adults (&gt;18 years) were included. Direct current cardioversion, RSI and procedural sedation were considered.

Data extraction:

Efficacy and safety endpoints were evaluated for all trials. For DCC and procedural sedation trials, efficacy measures included induction and recovery times, as well as the association for successful procedure. For the RSI trials, optimal intubating conditions were evaluated as the primary efficacy endpoint. Safety measures included hemodynamic changes, apnea rates and adverse effects.

Data synthesis:

In the setting of DCC, efficacy and safety outcomes were similar for propofol, thiopental, etomidate and methohexital. All of these agents provided markedly shorter induction and recovery times than midazolam. Patients who were pre-medicated with fentanyl exhibited prolonged recovery times and greater decreases in blood pressure. When used for RSI, propofol administration was associated with satisfactory intubating conditions that were comparable to those seen with thiopental and etomidate. Blood pressure reductions were seen in both DCC and RSI studies. Apneic episodes (&gt;30 seconds) occurred in 23% of propofol recipients, 28% of thiopental recipients and 7% of etomidate and midazolam recipients. Apart from the DCC studies described, no procedural sedation studies met our predefined review eligibility criteria.

Conclusion:

The body of literature evaluating propofol for DCC and RSI in the ED is limited. There is evidence to support the use of propofol for DCC and RSI, but this evidence comes from stable patients in non-ED settings. Further ED-based randomized comparative trials should be conducted before propofol is adopted for widespread use in the ED.

Efficacy, safety and patient satisfaction of propofol for procedural sedation and analgesia in the emergency department: a prospective study

Objective:

We evaluated the efficacy, safety and patient satisfaction with the use of propofol for procedural sedation and analgesia in the emergency department (ED).

Methods:

All patients receiving propofol for procedural sedation and analgesia in the ED between December 1, 2003, and November 30, 2005, were prospectively assessed. Propofol was administered using a standardized protocol, which included an initial dose of 0.25–0.5 mg/kg followed by 10–20 mg/minute until sedated. Efficacy was evaluated using procedural success rate, recovery time and physician satisfaction. Adverse respiratory effects were defined as apnea for more than 30 seconds or an oxygen saturation of less than 90%. Hypotension was defined as systolic blood pressure &lt; 90 mm Hg or &gt; 20% decrease from baseline. Patient and physician satisfaction were determined using 5-point Likert scales.

Results:

Our study included 113 patients with a mean age of 50 (standard deviation [SD] 19) years; 62% were male. The most common procedures were orthopedic manipulation (44%), cardioversion (37%), and abscess incision and drainage (13%). The mean total propofol dose required was 1.6 (SD 0.9) mg/kg. Procedural success was achieved in 90% of cases and the mean patient recovery time was 7.6 (SD 3.4) minutes. No patient (0%, 95% confidence interval [CI] 0%–3%) experienced apnea; however, 1 patient (1%, 95% CI 0%–5%) experienced emesis, which resulted in an oxygen saturation &lt;90%. Nine patients (8%, 95% CI 4%–15%) experienced hypotension and 7 (6%, 95% CI 3%–12%) experienced pain on injection. All patients were very satisfied (92%, 95% CI 85%–96%) or satisfied (8%, 95% CI 4%–15%), and 94% (95% CI 88%–98%) reported no recollection of the procedure. The majority of physicians were very satisfied (85%, 95% CI 77%–91%) or satisfied (6%, 95% CI 3%–12%) with the sedation and the conditions achieved.

Conclusion:

When administered as part of a standardized protocol, propofol appears to be a safe and effective agent for performing procedural sedation and analgesia in the ED, and is associated with high patient and physician satisfaction.

Synergistic antinociceptive interactions between fospropofol and alfentanil in mice

BACKGROUND

Combination therapy, which provides the opportunity to achieve optimal analgesia with reduced side effects at lower drug doses, is a valid approach for the treatment of pain. The analgesic interaction between fospropofol and alfentanil has not been investigated till date. We sought to determine the nature of the interaction between fospropofol and alfentanil in mice models of the formalin test, hot-plate test and the tail-flick test.

METHODS

The effects of fospropofol, alfentanil and their combinations were examined in the formalin-induced paw inflammatory hyperalgesia, the hot-plate test and the tail-flick test in mice. In the three models, dose-response curves were established and their respective ED50 (50% effective dose) values were determined separately for each agent. Fixed-ratio combinations of fospropofol and alfentanil were tested for their combined antinociceptive effects, and the type of interaction was determined by the isobolographic analysis.

RESULTS

Fospropofol, alfentanil and their combination produced a dose-dependent decrease in the number of flinches during phase 1 of the formalin test. In the hot-plate test and in the tail-flick test, fospropofol, alfentanil and their combination significantly and dose dependently prolonged the latency of withdrawal. In the three models, isobolographic analysis revealed a significant synergistic interaction between fospropofol and alfentanil. The ED50 value for the drug combination was significantly lower than the theoretical additive value (p<0.05).

CONCLUSIONS

The results demonstrate that fospropofol and alfentanil provide synergistic antinociceptive interactions in the formalin, hot-plate, and tail-flick tests. The observed synergistic interaction between fospropofol and alfentanil are indicative of the effectiveness of the combination treatment in pain management and should be explored further in patients undergoing minor surgical procedures.

Inhibition of acid-sensing ion channel currents by propofol in rat dorsal root ganglion neurons

Acid-sensing ion channels (ASICs), part of the epithelial sodium channel/degenerin family, are activated by extracellular protons. The ASICs play a significant role in the acidosis-mediated perception of pain. The anaesthetic agent propofol also exerts antinociceptive effects, but the underlying mechanisms for this effect are not clear. We used whole-cell patch clamping to investigate the effect of propofol on proton-gated currents in: (i) rat dorsal root ganglion (DRG) neurons; and (ii) HEK293 cells transfected with either ASIC1a or ASIC3. Propofol inhibited the amplitude of proton-gated currents in DRG neurons, but did not change the sensitivity of ASICs to H(+). Notably, propofol altered acid-evoked excitability of rat DRG neurons and decreased the number of action potentials induced by acid stimuli. In addition, we demonstrated that propofol inhibited ASICs by directly binding with these channels in HEK293 cells. These results suggest that propofol inhibits proton-gated currents in DRG neurons and that inhibition of proton-gated currents explains, in part, the antinociceptive effects of propofol in primary afferent neurons.

Magnesium sulfate with lidocaine for preventing propofol injection pain: a randomized, double-blind, placebo-controlled trial

PURPOSE

Propofol injection pain, despite various strategies, remains common and troublesome. This study aimed to test the hypothesis that pretreatment with the combination of intravenous lidocaine and magnesium would have an additive effect on reducing propofol injection pain.

METHODS

After institutional review board (IRB) approval and informed consent, we performed a prospective, double-blind, placebo-controlled, randomized trial. Subjects were randomly assigned to pretreatment with either lidocaine (50 mg), magnesium sulfate (0.25 mg), lidocaine (50 mg) plus magnesium sulfate (0.25 mg), or 0.9 % sodium chloride. Following pretreatment, propofol (50 mg) was administered, and subjects were questioned regarding injection site pain and observed for behavioral signs of pain.

RESULTS

Two hundred subjects were enrolled and 158 subjects (39 placebo, 38 lidocaine, 44 magnesium sulfate, and 37 lidocaine plus magnesium sulfate) received their assigned pretreatment intervention. Intergroup baseline characteristics were similar. The proportion of subjects reporting propofol injection pain was highest in those pretreated with magnesium sulfate (57 %), followed by those pretreated with placebo (46 %), lidocaine plus magnesium sulfate (41 %), and then lidocaine (29 %; p = 0.011). When adjusted for age, gender, diabetes mellitus, chronic pain, tobacco use, and selective-serotonin reuptake inhibitor use, the pain response scale scores were significantly reduced by lidocaine pretreatment compared to magnesium sulfate and placebo (p = 0.031 and p = 0.0003, respectively).

CONCLUSIONS

In this double-blind, placebo-controlled, randomized trial, the combination of intravenous magnesium sulfate and lidocaine offered no additional benefit for the relief of propofol injection pain compared to intravenous lidocaine alone. An improved, receptor-based understanding of the mechanism of propofol injection pain is still needed.

Intubation conditions in young infants after propofol and remifentanil induction with and without low-dose rocuronium

BACKGROUND

Bolus injections of intravenous propofol and remifentanil can be used in the tracheal intubation of infants and children, but relatively large doses are needed. We hypothesised that addition of a small bolus of rocuronium would ensure good intubation conditions when modest propofol and remifentanil doses were used.

METHODS

Seventy infants between 3 weeks and 4 months of age were randomised to receive either placebo or rocuronium. Anaesthesia was induced with IV propofol, 3 (3-5) mg/kg [median (range)]. Rocuronium (0.2 mg/kg) or placebo was then injected, followed 15 s later by 2 μg/kg remifentanil. One anaesthetist attempted tracheal intubation 1 min after the rocuronium/placebo injection and used the 'Copenhagen scoring system' to assess intubation conditions. The neuromuscular effect of 0.2 mg/kg rocuronium was recorded in another eight, already intubated, infants using thumb accelerometry during train-of-four stimulation of the ulnar nerve.

RESULTS

Intubation conditions were classified as 'poor' in 14 of 34 (41%) patients given placebo and in 10 of 36 (28%) patients given rocuronium (P = 0.32). There were four failed first attempts at intubation in the placebo group and none in the rocuronium group (P = 0.051). Maximum neuromuscular depression occurred 4 (3-8) after injection of 0.2 mg/kg rocuronium.

CONCLUSIONS

Intubation conditions were poor in almost one third of the patients receiving propofol-remifentanil. Adding a low-dose rocuronium did not significantly improve intubation conditions.

Efficacy of different doses of lidocaine in the prevention of pain due to propofol injection: a randomized, open-label trial in 120 patients

BACKGROUND

The incidence of pain due to propofol injection is high, but the most efficacious method of preventing this pain has not been identified.

OBJECTIVE

The aim of this study was to investigate the efficacy of lidocaine, at different doses and schedules, on propofol injection pain.

METHODS

In this open-label study, conducted at the Department of Anaesthesiology, Erciyes University Gevher Nesibe Hospital (Kayseri, Turkey), patients with American Society of Anesthesiologists Patient Acuity Classification I-II (ASA I-II) (ie, patients with absent [I] or mild [II] underlying systemic disease) aged 18 to 60 years undergoing various types of surgery were eligible. Patients were randomized to 1 of 4 treatment groups: group 1 received propofol; group 2, a combination of propofol plus lidocaine 10 mg; group 3, lidocaine 10 mg 30 seconds before propofol administration; and group 4, lidocaine 1 mg/kg 30 seconds before propofol administration (all drugs were administered intravenously). After cessation of the standard replacement fluid infusion (isotonic saline), propofol was given at a rate of 2 mL every 5 seconds until a dose of 2 mg/kg was reached. The patients were asked to rate their pain according to the following scale: 0 = none, 1 = mild, 2 = moderate, and 3 = severe.

RESULTS

A total of 120 patients (61 men, 59 women; mean [SD] age, 38.7 [8.9] years) were enrolled in the study (n = 30 patients in each group). The incidence of injection pain in groups 2 and 4 was significantly lower than that in groups 1 and 3 (all P<0.05), but no significant difference in the incidence of pain was found between groups 1 and 3. The incidence of pain in group 2 was significantly lower than that in group 4 (P<0.05).

CONCLUSIONS

In this study population, the addition of 10 mg of lidocaine to propofol 2 mg/kg, or the administration of 1 mg/kg of lidocaine 30 seconds before the administration of propofol 2 mg/kg, effectively decreased pain caused by propofol injection. Furthermore, a lower dose of lidocaine could be used. Based on our results, we suggest mixing propofol with 10 mg of lidocaine to decrease pain due to propofol injection during anesthesia induction.

Lidocaine for prevention of propofol injection-induced pain: A prospective, randomized, double-blind, controlled study of the effect of duration of venous occlusion with a tourniquet in adults

BACKGROUND

Many patients experience pain on injection of propofol. The use of lidocaine to prevent propofol injection pain is common. The analgesic effect of pre-injected lidocaine has been found to increase when a tourniquet is used.

OBJECTIVE

The aim of this study was to compare the effectiveness of various venous occlusion times with lidocaine analgesia to prevent pain during propofol injection.

METHODS

In this prospective, randomized, double-blind, controlled study, women aged 18 to 45 years, classifed as American Society of Anesthesiologists physical sta- tus I or II, who were scheduled to undergo elective surgery under general anesthesia induced with propofol, were randomly assigned to 1 of 5 groups: group 1, 2% lidocaine 20 mg in saline in a total volume of 10 mL and no venous occlusion; group 2, 2% lidocaine 20 mg in saline in a total volume of 10 mL plus venous occlusion for 15 seconds; group 3, 2% lidocaine plus venous occlusion for 30 seconds; group 4, 2% lidocaine plus venous occlusion for 60 seconds; and group 5, saline 10 mL and no venous occlusion. When the first 25% of the calculated propofol dose was administered, patients were asked about propofol-induced pain using a verbal pain scale (0 = no pain; 1 = mild pain; 2 = moderate pain; and 3 = severe pain). All patients and the anesthesiologist who evaluated pain severity were blinded to the study preparation being used.

RESULTS

The study comprised 100 women who were randomly divided into 5 groups of 20 patients each. Significantly more patients in group 5 (18 [90%] patients; P < 0.05) reported pain compared with the other treatment groups. In groups 2, 3, and 4, in which venous occlusion was applied, pain was reported during propofol injection in 6 (30%), 7 (35%), and 2 (10%) patients, respectively. The incidence of reported pain was significantly greater in group 1 (lidocaine without venous occlusion) than in group 4 (P < 0.05); however, the incidence of pain was similar in group 1 compared with groups 2 and 3.

CONCLUSIONS

The present study found that pretreatment with lidocaine 20 mg with or without venous occlusion significantly reduced the incidence and the severity of pain during the injection of propofol when compared with the group with no venous occlusion administered saline. In addition, pretreatment with lidocaine 20 mg plus venous occlusion for 60 seconds significantly reduced the incidence of propofol-induced pain compared with lidocaine without venous occlusion.

Cisatracurium pretreatment with tourniquet reduces propofol injection pain: a double-blind randomized controlled trial

OBJECTIVES

To investigate the efficacy of pretreatment with cisatracurium for prevention of pain associated with propofol injection, and compare its efficacy with that of lidocaine.

METHODS

Patients undergoing general anaesthesia were randomized to receive normal saline (control group), lidocaine (0.5 mg/kg), 0.03 mg/kg cisatracurium or 0.15 mg/kg cisatracurium. All drugs were administered into the largest dorsal vein of the hand with venous occlusion for 30 s, followed by propofol (0.5 mg/kg). Pain was evaluated using a four-point scale.

RESULTS

The incidence and severity of pain was significantly lower in the lidocaine and 0.15 mg/kg cisatracurium groups than the control and 0.03 mg/kg cisatracurium groups (n = 50/group). There was no significant difference between the lidocaine and 0.15 mg/kg cisatracurium groups in the incidence and severity of pain.

CONCLUSIONS

0.15 mg/kg cisatracurium effectively decreases the incidence and severity of pain induced by propofol injection without any significant complications.

Endoscopic sedation: from training to performance

Adequate sedation and analgesia are considered essential requirements to relieve patient discomfort and pain and ultimately to improve the outcomes of modern gastrointestinal endoscopic procedures. The willingness of patients to undergo sedation during endoscopy has increased steadily in recent years and standard sedation practices are needed for both patient safety and successful procedural outcomes. Therefore, regular training and education of healthcare providers is warranted. However, training curricula and guidelines for endoscopic sedation may have conflicts according to varying legal frameworks and/or social security systems of each country, and well-recognized endoscopic sedation training systems are not currently available in all endoscopy units. Although European and American curricula for endoscopic sedation have been extensively developed, general curricula and guidelines for each country and institution are also needed. In this review, an overview of recent curricula and guidelines for training and basic performance of endoscopic sedation is presented based on the current literature.

Paracetamol, ondansetron, granisetron, magnesium sulfate and lidocaine and reduced propofol injection pain

Background:

Propofol is a most widely used intravenous anesthetic drug. One of its most common complications is the pain upon injection; therefore, different methods, with various effects, have been proposed in order to alleviate the pain.

Objectives:

This study investigates the effects of paracetamol, ondansetron, granisetron, magnesium sulfate and lidocaine drugs on reducing the pain of propofol injection during anesthetic induction. Also, the hemodynamic changes will be analyzed.

Patients and Methods:

This is an interventional study containing 336 patients underwent elective orthopedic surgeries in Educational Hospitals of Mashhad University, using systematic sampling, the patients were divided into six groups. A 20-gauge needle was inserted into a venous vessel in the back of the hand and 100 cc of Ringer serum was injected into the vein, which was applied proximal to the injection site. Afterwards, paracetamol 2 mg/kg (group p), magnesium sulfate 2 mmol (group M), ondansetron 4 mg (group O), granisetron 2 mg (group G), lidocaine 40 mg (group L) and 5 cc saline (group S) were injected into the vessel, after 60 seconds, the tourniquet was opened. One quarter of the total dose of propofol (2.5 mg/kg) was injected with a flow rate of 4 mg/sec and then the injection pain was measured. Finally, the fentanyl (2 µg/kg), atracurium 0.5 mg/kg, and the remaining dose of propofol were injected and the vital signs were recorded before the administration of propofol and 1, 3, 5 and 10 minutes after the propofol injection.

Results:

The six groups did not significantly differ, regarding their gender, weight or age. Propofol injection pain was less in L and G groups, in comparison with the others (P ≤ 0.001). By analyzing the hemodynamic changes, it was observed that the least amount of change in mean arterial pressure was observed in the paracetamol group.

Conclusions:

The reduction of propofol injection pain was observed by using medications (in comparison with normal saline), but it was more significant in groups G and L. Moreover, Hypotension was higher in groups S and G and it was lessened in group P.

Effect of lidocaine volume and concentration on preventing incidence and severity of propofol injection pain

Background:

Propofol is one of common anesthetic drugs used in anesthesia. The most common side effects of propofol are local pain. Pretreatment with lidocaine can reduce propofol injection pain.

Objectives:

The aim of the present study was to assess and compare the efficiency of lidocaine 0.4% and 2% in reducing the incidence and severity of propofol injection pain.

Patients and Methods:

This was a double blind prospective clinical trial on children 4-8 years old with class ASA I and II candidates who were referred to Dr. Shaikh Hospital in Mashhad for elective surgery. Sample size calculated 50 patients in each groups based on pilot study. 100 children's were randomly divided equally in two groups, who were injected with lidocaine solutions 2% and 0.4% respectively. patient's pain evaluation based on VSD (verbal descriptor scale) and NRS (Numeric Rating Scale) using patient's verbal reaction and behavior namely fretting, hand drag and tearing. The collated data was analyzed.

Results:

There was nosignificant difference as to the first three variables (age, gender and weight P > 0.2). The significant difference regarding pain experience in both groups was noteworthy (P > 0.2).

Conclusions:

Most of the studies compared lidocaine with other drugs or its efficiency at different doses. Our study is different in that we applied a constant dose of lidocaine in various volumes and concentration. This result shows that lidocaine with the same does but lower concentration and higher volume is more effective in preventing propofol injection pain. Using diluted lidocaine with the dosage of 1 mg/kg and a concentration of 0.4% is an effective way to relieve pain caused by propofol injection in children.

Intravenous lidocaine pretreatment with venous occlusion for reducing microemulsion propofol induced pain: Comparison of three doses of lidocaine

Objective

Pretreatment with intravenous 40 mg or 0.5 mg/kg lidocaine with venous occlusion is recommended to prevent pain following injection of lipid emulsion propofol. This approach is not sufficient to prevent pain from the injection of microemulsion propofol. The present study investigated whether a higher dose of lidocaine pretreatment with venous occlusion would be more effective for reducing pain following injection of microemulsion propofol compared with 40 mg lidocaine.

Methods

Patients undergoing elective surgery were randomly assigned to one of three groups: pretreatment with 40 mg (group L40), 60 mg (group L60) or 80 mg (group L80) lidocaine intravenously with venous occlusion, followed by injection with microemulsion propofol 1 min later. Pain was assessed on a four-point scale (severe, moderate, mild, none) based on physical responses to the injection.

Results

A total of 68 patients were included in the final analysis. Pain severity and incidence were significantly lower in patients in group L60 and L80 compared with patients in group L40. There were no statistically significant differences in pain incidence or severity between group L60 and group L80.

Conclusions

Pretreatment with 60 mg lidocaine intravenously with venous occlusion may be the most effective minimum dose for reducing injection pain following microemulsion propofol administration for induction of anaesthesia.

Comparison of the preventive effects of pretreatment of lidocaine with a tourniquet and a premixed injection of lidocaine on propofol-LCT/MCT injection pain

BACKGROUND

Lidocaine has been used widely to prevent propofol injection pain. Various methods of administration exist, such as lidocaine premixed with propofol or lidocaine pretreatment using a tourniquet, but it is unclear which method of lidocaine administration is more effective for the prevention of injection pain of propofol LCT/MCT. The purpose of this study was to compare pretreatment of lidocaine with a tourniquet and a premixed injection of lidocaine to prevent injection pain of propofol-LCT/MCT.

METHODS

Patients were randomly allocated into the pretreatment group (n = 117) or the premixed group (n = 117). The pretreatment group was pretreated with 2 ml of lidocaine 2%, held with a tourniquet, before propofol-LCT/MCT injection. The premixed group was injected with a premixed solution of propofol-LCT/MCT and 2 ml of lidocaine 2%. To evaluate the incidence and severity of pain, spontaneous verbal expressions of pain, movement of hand, frowning, and moaning were recorded, and the patients were asked to recall their pain with the visual analogue score (VAS) 30 minutes after awakening from anesthesia.

RESULTS

Overall, injection pain occurred in 13.7% of the pretreatment group and 15.4% of the premixed group, without any statistical difference (P = 0.71). There was no difference in spontaneous verbal expressions of pain, movement of hand, frowning, and moaning between the two groups. The pain intensity (VAS) also showed no difference between the two groups (P = 0.49).

CONCLUSIONS

Pretreatment of lidocaine with a tourniquet showed no more benefit to prevent injection pain of propofol LCT/MCT compared to a premixed injection with lidocaine.

Analgesic effects of palonosetron in the intravenous propofol injection

Background

Propofol is a good induction agent, but it has the disadvantage of causing pain on intravenous injection. The incidence of propofol-induced pain is approximately 70%. Palonosetron is a novel second-generation 5-hydroxytryptamine type 3 (5-HT3) receptor antagonist. We presumed that palonosetron would be effective in reducing the occurrence of propofol-induced pain based on similar mechanisms to other 5-HT3 receptor antagonists.

Methods

Eighty patients were randomized to either Group N (0.9% sodium chloride [normal saline] 2 ml, n = 40) or Group P (palonosetron 0.075 mg, 2 ml, n = 40). Patients were intravenously given a 2 ml pretreatment solution, containing either palonosetron 0.075 mg or normal saline. Following pretreatment with 2 ml of palonosetron 0.075 mg or normal saline, we manually occluded venous drainage midarm with the help of an assistant. One minute later, we released the occlusion of venous drainage. This was followed by a 5-second propofol injection at 25% of the total calculated doses. Patients were then interviewed about whether or not they experienced propofol-induced pain.

Results

Overall, the incidence of propofol-induced pain was 60% in the normal saline group and 27.5% in the palonosetron group. No patients in the palonosetron group experienced severe pain. The incidence of propofol-induced pain was significantly lower in the palonosetron group compared to the normal saline group (P < 0.01).

Conclusions

Following pretreatment with palonosetron, 72.5% of patients experienced a decrease in the occurrence of propofol-induced pain.

Reducing waste from incomplete or unusable reports of biomedical research

Research publication can both communicate and miscommunicate. Unless research is adequately reported, the time and resources invested in the conduct of research is wasted. Reporting guidelines such as CONSORT, STARD, PRISMA, and ARRIVE aim to improve the quality of research reports, but all are much less adopted and adhered to than they should be. Adequate reports of research should clearly describe which questions were addressed and why, what was done, what was shown, and what the findings mean. However, substantial failures occur in each of these elements. For example, studies of published trial reports showed that the poor description of interventions meant that 40-89% were non-replicable; comparisons of protocols with publications showed that most studies had at least one primary outcome changed, introduced, or omitted; and investigators of new trials rarely set their findings in the context of a systematic review, and cited a very small and biased selection of previous relevant trials. Although best documented in reports of controlled trials, inadequate reporting occurs in all types of studies-animal and other preclinical studies, diagnostic studies, epidemiological studies, clinical prediction research, surveys, and qualitative studies. In this report, and in the Series more generally, we point to a waste at all stages in medical research. Although a more nuanced understanding of the complex systems involved in the conduct, writing, and publication of research is desirable, some immediate action can be taken to improve the reporting of research. Evidence for some recommendations is clear: change the current system of research rewards and regulations to encourage better and more complete reporting, and fund the development and maintenance of infrastructure to support better reporting, linkage, and archiving of all elements of research. However, the high amount of waste also warrants future investment in the monitoring of and research into reporting of research, and active implementation of the findings to ensure that research reports better address the needs of the range of research users.

Reducing the pain of microemulsion propofol injections: a double-blind, randomized study of three methods of tourniquet and lidocaine

BACKGROUND

Although the new formulation of lipid-free microemulsion propofol (MP) has some advantages over the lipid emulsion, it reportedly produces more injection pain than lipid-based propofol. Intravenous lidocaine with application of a rubber tourniquet before administration of propofol is considered to be the best method for reducing injection pain; however, this technique is not perfect.

OBJECTIVE

The goal of this study was to evaluate the effect of different methods of tourniquet application and lidocaine administration on MP injection pain.

METHODS

This single-center, randomized controlled clinical trial was conducted in 140 patients aged 18 to 65 years. Patients were randomly divided into 4 groups (n = 35 each). Group A received MP (2 mg/kg) after lidocaine (0.6 mg/kg) with a tourniquet with arm down (venous engorgement); group B received MP after lidocaine with a tourniquet with arm up (venous gravity drainage); group C received MP with a tourniquet with arm down; and group D (control group) received MP only (with no tourniquet). In groups A and C, the tourniquet was released after MP; in group B, the tourniquet was released before MP. Injection pain was evaluated by using a verbal pain score (VPS). The bispectral index, the time from the beginning of drug injection to the loss of eyelash reflex, and time to the lowest bispectral index value were recorded.

RESULTS

Group A showed significantly less incidence of pain than the control group when MP was injected. The mean VPS was significantly lower in groups A, B, and C than in group D (the control group). The VPS of group A was significantly lower than that in group B. Other observed values were not significantly different.

CONCLUSIONS

We concluded that intravenous retention of lidocaine with the application of a rubber tourniquet under venous engorgement of the arm reduces the incidence and intensity of MP injection pain.

CLINICAL TRIAL REGISTRY

UMIN000010725.

An effective dose of ketamine for eliminating pain during injection of propofol: a dose response study

BACKGROUND AND PURPOSE

Ketamine can completely eliminate pain associated with propofol injection. However, the effective dose of ketamine to eliminate propofol injection pain has not been determined. The purpose of this study was to determine the effective dose of ketamine needed to eliminate pain in 50% and 95% of patients (ED50 and ED95, respectively) during propofol injections.

METHODS

This study was conducted in a double-blinded fashion and included 50 patients scheduled for elective gynecological laparoscopy under general anesthesia. The initial dose of ketamine used in the first patient was 0.25mg/kg. The dosing modifications were in increments or decrements of 0.025 mg/kg. Ketamine was administered 15 seconds before injecting propofol (2.5mg/kg), which was injected at a rate of 1mL/s. Patients were asked to rate their pain during propofol injection every 5s econds using a 0-3 pain scale. The highest pain score was recorded. The ED50, ED95 and 95% confidence intervals (CI) were determined by probit analyses.

RESULTS

The dose of ketamine ranged from 0.175 to 0.275 mg/kg. The ED50 and ED95 of ketamine for eliminating pain during propofol injection were 0.227 mg/kg and 0.283 mg/kg, respectively (95%CI: 0.211-0.243 mg/kg and 0.26-0.364 mg/kg, respectively).

CONCLUSION

Ketamine at an approximate dose of 0.3mg/kg was effective in eliminating pain during propofol injection.

The effect of intravenous dexamethasone and lidocaine on propofol-induced vascular pain: a randomized double-blinded placebo-controlled trial

Background. The mechanism for pain associated with intravenous administration of propofol is believed to be related to the release of nitric oxide. We hypothesized that pain following propofol injection would be reduced by pretreatment with dexamethasone. Methods. One hundred fourteen female subjects received 5 mL of preservative-free saline, 0.5 mg·kg⁻¹ of lignocaine hydrochloride 10 mg·mL⁻¹ or 0.25 mg·kg⁻¹ of dexamethasone, intravenously, following exsanguination and occlusion of the veins of the arm. This was followed by a 0.5 mg·kg⁻¹ injection of propofol. Pain scores, facial grimacing, arm withdrawal, and vocalization were recorded prior to and at 15 and 30 seconds following the injection of propofol. Results. The incidence of moderate to severe pain following the injection of propofol was significantly decreased with both lidocaine and dexamethasone. Hand withdrawal was also significantly decreased in comparison to saline. Conclusion. Low dose dexamethasone is commonly used as an antiemetic, and, in larger doses, it has been demonstrated to provide prolonged postoperative analgesia. At higher analgesic doses, dexamethasone may also reduce pain associated with the injection of propofol. This effect is probably related to the effect of the steroid on nitric oxide production associated with intravenous propofol injection.

Desflurane but not sevoflurane augments laryngeal C-fiber inputs to nucleus tractus solitarii neurons by activating transient receptor potential-A1

AIMS

Volatile anesthetics have distinct odors and some are irritating to the upper airway and may cause cough and laryngospasm, which may result, in part, from stimulation of C-fiber reflex. Local exposure of such anesthetics increases the sensitivity of capsaicin-sensitive laryngeal C-fiber endings compatible with airway irritability presumably by activation of transient receptor potential (TRP) ion channels, but the physiological relevance of this sensitization transmitted to the higher-order neurons in the central reflex pathway and output is unknown.

MAIN METHODS

In anesthetized young guinea pigs, baseline and left atrial capsaicin evoked changes in the extracellular unit activity of laryngeal C-fiber-activated neurons in the nucleus tractus solitarii (NTS) and phrenic nerve activity were compared between irritant (desflurane) and non-irritant (sevoflurane) anesthetic gas exposure to the isolated larynx.

KEY FINDINGS

Desflurane significantly augmented the peak and duration (p<0.01) of the NTS neuronal responses and the prolongation of expiratory time (p=0.017). The effect was enhanced by iontophoretic application of the TRPA1 agonist allyl-isothiocyanate (p<0.05), inhibited by TRPA1 antagonist HC-030031 (p<0.01), but not by TRPV1 antagonist BCTC. Sevoflurane did not affect the central pathway.

SIGNIFICANCE

Thus, the sensitization of the laryngeal C-fiber endings by irritant volatile anesthetics is transmitted to the NTS via activation of the TRPA1 and is associated with a prolonged reflexively evoked expiratory apnea. The findings may help to explain local deleterious effects of irritant volatile general anesthetics on the airways during inhaled induction or bronchodilator therapy for status asthmatics.

Effect of lidocaine (40 mg) mixed to prevent injection pain of propofol on the intubating conditions and onset time of rocuronium

Background

To analyze how lidocaine 40 mg mixed prevents injection pain of propofol affects the onset time of rocuronium, tracheal intubating conditions and intubation related hemodynamic changes.

Methods

This study consisted of 70 patients with an American Society of Anesthesiologists (ASA) physical status class 1 or 2 for general anesthesia. All the patients were randomly allocated into two groups: propofol 2 mg/kg plus normal saline 2 ml (Group C) and propofol 2 mg/kg plus 2% lidocaine 40 mg (Group L). Each group was administrated intravenously during induction and the patient was intubated 1 minute after an injection of 0.6 mg/kg of rocuronium. The time at disappearance of the first twitch and intubation scores were recorded. Also, blood pressure and heart rate were measured at the baseline, after intravenous injection of propofol, before intubation, and at 0, 1, 2, 3 and 5 minutes after intubation.

Results

There were no significant differences between group C and L (P > 0.05).

Conclusions

40 mg of lidocaine mixed with propofol to prevent injection pain did not affect the onset time of rocuronium, intubating conditions and intubation related hemodynamic changes.

Synthesis and characterization of novel quick-release propofol prodrug via lactonization

The water-soluble derivatives of propofol have gained attention as a method to increase solubility of propofol. According to the principle of lactonization, the lead compound HX0969 was synthesized first and then the pharmacological features of HX0969 were evaluated in a comparison with those of propofol in the SD rats. Then, HX0969 disodium phosphate monoester (HX0969W) and glycine ester trifluoroacetic acid salt (HX101230) were synthesized, and their pharmacological features were compared with those of Lusedra®, which has been recognized and marketed as a water-soluble prodrug of propofol since 2008. The results showed that HX0969 could produce an anesthetic effect within a few seconds (3.6±3.0s) and its therapeutic index was 4.66 in the SD rat. The pharmacodynamic characteristics of HX0969W were similar to those of the Lusedra®. HX101230 could still produce an anesthetic effect within 60s in the rats though its therapeutic index was not so high (TI=2.96). Therefore, our study has indicated that HX0969 is a potentially useful lead compound of propofol derivative. Its rapid anesthetic effect is probably associated with lactonization.

Efficacy of intravenous lidocaine to reduce pain and distress associated with propofol infusion in pediatric patients during procedural sedation

BACKGROUND

Research suggests that young children experience an increased incidence and severity of discomfort during propofol infusion. Evaluations of varied interventions to reduce or eliminate this discomfort with adult subjects suggest that premedication with intravenously administered lidocaine (0.5 mg/kg) offers the best overall effectiveness.

OBJECTIVE

Because this regimen's efficacy in a pediatric population is undocumented, we conducted a randomized, double-blind, placebo-controlled study to determine the effectiveness of intravenous lidocaine pretreatment to alleviate pain in pediatric subjects before propofol infusion.

METHODS

Subjects (aged 2-7 years) scheduled for painless diagnostic procedures received either a saline placebo or 1 of 2 lidocaine doses before administering propofol. To capture the patient's baseline behavioral state, a trained observer administered the validated face, legs, activity, cry, consolability pain assessment scale before propofol infusion. During deep sedation induction, the sedating physician, a trained research assistant, and the patient's parent documented maximum distress using a 100-mm visual analog scale (VAS).

RESULTS

Ninety-one subjects participated. We found no difference in VAS pain scores between groups pretreated with lidocaine 0.25 mg/kg, lidocaine 0.5 mg/kg, and placebo. Statistical analysis also found no interrater differences between parents, physician, or observer VAS scores.

CONCLUSIONS

Our data do not support using lidocaine pretreatment to alleviate pain/discomfort in pediatric patients during propofol infusion.

A prospective, randomized, double-blind study to compare the efficacy of lidocaine + metoclopramide and lidocaine + ketamine combinations in preventing pain on propofol injection

PURPOSE

Propofol injection is known to cause distressing pain, and various methods have been used to decrease this pain. We investigated the efficacy of the lidocaine + metoclopramide and lidocaine + ketamine combinations on modulating propofol injection pain.

METHODS

Ninety ASA I/II patients aged 20-60 years were randomly assigned to three groups to receive lidocaine 20 mg (group L), lidocaine 20 mg + metoclopramide 10 mg (group LM), or lidocaine 20 mg + ketamine 5 mg (group LK), respectively, with venous occlusion for 1 min using a forearm tourniquet. Propofol 0.5 mg/kg was subsequently administered into a dorsal hand vein, and pain was assessed during its injection using a verbal rating score. The results were analyzed statistically with analysis of variance, the chi-square test, and the Wilcoxon rank sum test, where appropriate. The significance level was set at p < 0.05.

RESULTS

The incidence of pain was rated to be significantly less in patients in groups LM (40 %) and LK (6.7 %) than in those in group L (83.3 %) (p = 0.001 and p < 0.001, respectively). The pain score [median (range)] was also significantly less in patients in groups LM [0 (0-3)] and LK [0 (0-2)] than in those in group L [2 (0-3)] (p = 0.001 for both groups).

CONCLUSION

The lidocaine-ketamine combination is most effective for decreasing the pain on propofol injection.

A comparative study of non-lipid nanoemulsion of propofol with solutol and propofol emulsion with lecithin

BACKGROUND AND OBJECTIVES

Some formulations have been proposed to reduce the adverse reactions due to the lipid emulsion containing soybean oil used as propofol carrier. This study for endoscopy sedation was aimed at evaluating and comparing the safety, effectiveness and adverse effects of the use of propofol nanoemulsion compared to propofol currently commercialized.

METHOD

In this prospective study, 150 patients were submitted to upper digestive endoscopy. These patients were allocated into two groups: the control group (CONT Group; n=75) and the nanoemulsion group (NE Group; n=75). HR, SBP, DBP, SpO(2) and BIS (which is considered to be appropriate between 65 and 75 during procedure) were monitored. Gender, age, weight, height, BMI, ASA physical status, times and doses were analyzed, as well as adverse effects (phlogistic signs and pain on injection, apnea, nausea/vomiting) and alterations in monitoring variables. A p-value < 0.05 was considered significant.

RESULTS

The groups had similar results concerning anthropometric data and physical status. None of the patients developed apnea or presented phlogistic signs in the injection site. The incidence of pain on injection in the CONT Group was 82.7% and 53.3% in the NE Group (p<0.001), and the incidence of nausea and vomiting was 10.7% in the CONT Group and 2.7% in the NE Group (p>0.05). The times, induction doses and the SBP and DBP values at the end of examination and at the moment of discharge from the PACU were lower in the NE Group (p<0.05).

CONCLUSIONS

Lipid propofol and propofol nanoemulsion were equivalent concerning effectiveness, safety and adverse effects in the doses used. There was a lower incidence of pain on injection in the nanoemulsion formulation.

Efficacy of Lignocaine plus Ketamine at Different Doses in the Prevention of Pain Due to Propofol Injection

OBJECTIVE

Pain on injection is still a major problem with propofol. Lignocaine (lidocaine) is effective in preventing propofol-induced pain on injection, but cannot entirely control the pain. The purpose of this study was to examine the effect of lignocaine plus ketamine, an N-methyl-D-aspartate receptor antagonist, on pain on injection of propofol.

DESIGN

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

SETTING

University Hospital.

PATIENTS

120 female patients scheduled for gynaecological laparoscopy.

INTERVENTIONS

Patients received intravenously lignocaine 20mg plus either placebo (saline) or ketamine at three different doses (2.5mg, 5mg and 10mg), with manual venous occlusion for 1 minute, followed by administration of propofol 0.5 mg/kg into a dorsal hand vein (n = 30 in each group). A blinded researcher asked the patients to assess pain during the propofol injection. MAIN OUTCOMES MEASURES AND RESULTS: Twelve of 30 patients (40%) complained of pain in the lignocaine/placebo group compared with three (10%) in the lignocaine/ketamine 5mg group and three (10%) in the lignocaine/ketamine 10mg group (both p = 0.015). No significant differences were found between the lignocaine/ketamine 2.5mg (10 patients [33%]) and lignocaine/placebo groups. No complications such as pain, oedema, wheal or flare response were observed at injection sites within the first 24 hours after anaesthesia.

CONCLUSION

Combined lignocaine 20mg and ketamine 5mg, with manual venous occlusion, is more effective than lignocaine 20mg alone for pain control during propofol injection.

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.

Receptor specificity defines algogenic properties of propofol and fospropofol

BACKGROUND

Propofol-evoked injection site pain is not observed with fospropofol. We hypothesized that unlike propofol, fospropofol does not activate the irritant receptor, transient receptor potential 1 (TRPA1).

METHODS

We tested the hypothesis using electrophysiology and behavioral studies.

RESULTS

Our data demonstrate that propofol (100 μM) evokes an inward current only in TRPA1-expressing neurons. However, fospropofol (100 μM and 1 mM) is unable to evoke depolarizing currents in either TRPA1-positive or TRPA1-negative neurons. Both propofol and fospropofol produced general anesthesia.

CONCLUSIONS

The lack of algogenic activity in fospropofol is most likely the result of its inability to activate TRPA1 on nociceptors.

Drug-administration sequence of target-controlled propofol and remifentanil influences the onset of rocuronium. A double-blind, randomized trial

BACKGROUND

Remifentanil is known to cause bradycardia and hypotension, as well as the decreases of cardiac output (CO). We hypothesized that hemodynamic suppression by remifentanil would affect the onset time of rocuronium. This study investigated whether the onset of rocuronium was influenced by the drug-administration sequence during induction of anesthesia with target-controlled infusion of propofol and remifentanil.

METHODS

Healthy adult patients (n = 126) undergoing elective surgery under general anesthesia were randomized into two groups according to drug-administration sequence. In Remi-Pro-Rocu group (n = 62), remifentanil was infused first, followed by propofol. Then, rocuronium was administered lastly. In Pro-Rocu-Remi group (n = 64), propofol, rocuronium, and remifentanil were given in that order. As a primary outcome, the onset time of rocuronium was measured. Mean arterial pressure (MAP), heart rate (HR), CO, and stroke volume were recorded before anesthesia (T1), at injection of rocuronium (T2), immediately before and after intubation (T3 and T4).

RESULTS

In Remi-Pro-Roc group, the onset of rocuronium was delayed significantly compared with Pro-Rocu-Remi group [median (interquartile range); 130 (105-150) vs. 90 (71-100) s, P < 0.001]. At the time of rocuronium injection (T2), MAP, HR, and CO were significantly lower in Remi-Pro-Rocu group than Pro-Rocu-Remi group (P < 0.001).

CONCLUSION

The onset time of rocuronium is prolonged significantly by early administration of remifentanil during target-controlled infusion of propofol and remifentanil, and it may be due to the decreased CO caused by remifentanil.