Prevention of pain on injection with propofol: a quantitative systematic review

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.

Prevention of pain on injection of propofol using ice gel pack versus pre-treatment with lignocaine: a randomized controlled trial

PURPOSE

Regardless of the positive attributes of propofol, it is frequently associated with pain on injection. We compared the efficacy of topical cold thermotherapy using an ice gel pack with intravenous lignocaine pre-treatment for reducing pain on propofol injection.

METHODS

This single-blinded randomized controlled trial was conducted in 200 American Society of Anesthesiologists physical status I, II, and III patients scheduled for elective/emergency surgery under general anesthesia. The patients were randomized into two groups: the Thermotherapy group- receiving an ice gel pack proximal to the intravenous cannula for 1 min, or the Lignocaine group-receiving 0.5 mg/kg of lignocaine administered intravenously, with occlusion proximal to the site of the intravenous cannula for 30 s. The primary objective was to compare the overall incidence of pain after propofol injection. The secondary objectives included the incidence of discomfort on the application of an ice gel pack, comparison of dose of propofol needed for induction, and hemodynamic changes at induction, between the two groups.

RESULTS

Fourteen patients in the lignocaine group and 15 patients in the thermotherapy group reported pain. The incidence of pain and the distribution of pain scores were comparable among groups (p = 1.00). Patients of the lignocaine group required significantly less amount of propofol for induction as compared to the thermotherapy group (p = 0.001).

CONCLUSION

Topical thermotherapy using an ice gel pack was not found superior to lignocaine pre-treatment in alleviating pain on injection of propofol injection. However, topical cold therapy using an ice pack remains a non-pharmacological technique that is easily available, reproducible, and cost-effective. Further studies are required to prove its equivalence to lignocaine pre-treatment.

TRIAL REGISTRATION

CTRI (CTRI/2021/04/032950).

Safety, pharmacokinetics and pharmacodynamics of a novel γ-aminobutyric acid (GABA) receptor potentiator, HSK3486, in Chinese patients with hepatic impairment

BACKGROUND

The primary objective of this study was to investigate if hepatic impairment alters the safety, pharmacokinetics, and pharmacodynamics of HSK3486.

RESEARCH DESIGN AND METHODS

This was a clinical trial of HSK3486 in subjects with normal hepatic function (n = 8), and mild (Child-Pugh A; n = 8), or moderate (Child-Pugh B; n = 8) hepatic impairment. Each subject received an IV bolus dose of 0.4 mg/kg HSK3486 for 1 min, immediately followed by a maintenance infusion of 0.4 mg/kg/h HSK3486 for 30 min.

RESULTS

In total, 24 subjects were enrolled and completed the study. HSK3486 was generally well tolerated by all subjects. There were no serious AEs and no deaths reported during the study. The incidence of AEs was numerically highest in subjects with moderate hepatic impairment. The exposure (AUC) of HSK3486 increased gradually with the decrease in hepatic function; however, degree of hepatic impairment had little effect on HSK3486 PD (MOAA/S and BIS).

CONCLUSIONS

Overall, there were no clinically relevant differences in HSK3486 exposure or PD in subjects with mild or moderate hepatic impairment compared to normal control. These data imply that HSK3486 dose adjustment is not warranted in subjects with mild or moderate hepatic impairment.

TRIAL REGISTRATION

The trial is registered at ClinicalTrials.gov (CT.gov identifier: NCT04145596).Key MessageHSK3486 at an IV bolus dose of 0.4 mg/kg and a maintenance infusion of 0.4 mg/kg/h was safe and well tolerated by all mild or moderate hepatic impairment subjects and normal hepatic function subjects.There were no clinically relevant differences in HSK3486 exposure or PD in subjects with mild or moderate hepatic impairment compared to subjects with normal hepatic function.HSK3486 dose adjustment is not required in subjects with mild or moderate hepatic impairment.

Evaluation of Propofol-Sparing Effect of Intravenous Lignocaine in Patients Undergoing Daycare Upper Gastrointestinal Endoscopic Procedures

Background Propofol is the most common sedative for endoscopies. Propofol alone may require larger doses for adequate level of sedation. Lignocaine is known for its anesthetic-sparing effect. We tested whether the addition of intravenous lignocaine to propofol-based sedation reduces its dose. Methods This prospective, randomized study was performed on 90 patients of 18 to 60 years of age, of either sex of the American Society of Anesthesiologists (ASA) Grade-I & II, and was divided into two groups. Group L + P received IV bolus of 1.5 mg/kg 2% lignocaine over 10 minutes followed by 1.5 mg/ kg/ h infusion and group NS + P- received the equivalent volumes of normal saline in bolus and infusion. Patients were induced with fentanyl (2 µg/kg) and propofol (1 mg/kg). To maintain an adequate sedation level, a supplemental bolus of 0.5 mg /kg propofol was administered. The outcomes recorded were the total and supplemental amount of propofol administered, as well as recovery time. Results The mean supplemental propofol for group L + P and group NS + P- 37.00 ± 29.93 and 58.67 ± 19.49 mg, respectively and mean total propofol consumption was 98.22 ± 34.00 mg and 131.11 ± 23.18 mg, respectively, (p < 0.001). Mean recovery time in group L + P was also shorter (5.22 ± 2.14 versus 9.96 ± 2.14). The incidence of adverse events like gag reflux, upper airway obstruction, pain on injection, and hypotension was significantly lower in group L + P (p < 0.05). Conclusion The addition of lignocaine to propofol-based sedation reduced the overall propofol requirement at the same time maintaining hemodynamic stability, spontaneous respiration, and early recovery.

A comparison of ondansetron and lidocaine in reducing injection pain of propofol: a randomized controlled study

Background

Direct stimulation of the afferent nerve endings in the venous endothelium is one explanation of propofol injection pain. Previous studies found that ondansetron can also block sodium channels. This effect is similar to that of lidocaine.

Objective

The primary outcome was the efficacy of ondansetron compared to lidocaine and placebo for the reduction of propofol injection pain.

Method

This trial was conducted in 240 patients, American Society of Anesthesiologists classification I-III and aged between 18–65 years old, undergoing elective surgery, and having a 20-gauge intravenous catheter at the hand dorsum. Each group of 80 patients received 8 mg. of ondansetron in the O Group, 40 mg. of lidocaine in the L Group and normal saline in the C Group. The study medications were blindly administered to the patients through a 20-gauge intravenous catheter placed on the hand dorsum, and then 1 min later, the small dose of propofol (50 mg.) was infused via the syringe pump at a rate of 600 ml/hr. for 30 s. Following that, the syringe pump of propofol was temporarily stopped, and the patients were asked to rate their pain at the injection site.

Result

The incidence of pain was lowest in the L group (66.2%) compared with the O (82.5%) and the C groups (85.0%) (P < 0.01). The median pain score in the L, O, and C groups were 2 (0–4), 4 (2–5), and 4.5 (2–6), respectively (P < 0.01). The incidences of no pain, mild, moderate, and severe pain were also significantly different in the L group (33.8%, 37.5%, 21.2%, and 7.5%, respectively) compared with those in the O group (17.5%, 31.2%, 31.2%, and 20.0%, respectively) and the C groups (15.0%, 22.5%, 40.0%, and 22.5%, respectively) (P < 0.01).

Conclusion

Pretreatment with intravenous lidocaine, rather than ondansetron, can reduce the incidence and intensity of propofol-induced pain.

Hippocampal SIRT1-Mediated Synaptic Plasticity and Glutamatergic Neuronal Excitability Are Involved in Prolonged Cognitive Dysfunction of Neonatal Rats Exposed to Propofol

Neonates who receive repeated or prolonged general anesthesia before the age of 4 are at a significantly higher risk of developing cognitive dysfunction later in life. In this study, we investigated the effects of repeated neonatal propofol exposure on hippocampal synaptic plasticity, neuronal excitability, and cognitive function. Adeno-associated SIRT1 virus with CaMKIIɑ promotor and a viral vector carrying the photosensitive gene ChR2 with the CaMKIIɑ promotor, as well as their control vectors, were stereotaxically injected into the hippocampal CA1 region of postnatal day 5 (PND-5) rats. PND-7 rats were given intraperitoneal injection of 60 mg/kg propofol or fat emulsion for three consecutive days. Western blotting, Golgi staining, and double immunofluorescence staining were used to evaluate the SIRT1 expression, synaptic plasticity, and the excitability of neurons in the hippocampal CA1 region. The Morris water maze (MWM) test was conducted on PND-30 to assess the learning and memory abilities of rats. Repeated neonatal propofol exposure reduced SIRT1 expression, suppressed synaptic plasticity, decreased glutamatergic neuron excitability in the hippocampus, and damaged learning and memory abilities. Overexpression of SIRT1 attenuated propofol-induced cognitive dysfunction, excitation-inhibition imbalance, and synaptic plasticity damage. After optogenetic stimulation of glutamatergic neurons in the hippocampal CA1 region, the learning and memory abilities of rats exposed to propofol were improved on PND-30. Our findings demonstrate that SIRT1 plays an important role in cognitive dysfunction induced by repeated neonatal propofol exposure by suppressing synaptic plasticity and neuronal excitability.

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).

Safety, Pharmacokinetics, and Pharmacodynamics of a Single Bolus of the γ-aminobutyric Acid (GABA) Receptor Potentiator HSK3486 in Healthy Chinese Elderly and Non-elderly

Background: The present clinical trial investigated the potential influences of dosage and age on the pharmacokinetic properties and safety profile of HSK3486, and whether any adjustment in dosing regimen is necessary in elderly patients.

Methods: Twenty-four elderly participants (65–73 years) were apportioned to three equal cohorts to receive a single IV bolus of 0.2, 0.3, and 0.4 mg/kg HSK3486, respectively. An additional control group comprised eight non-elderly participants (21–44 years), who each received a single IV bolus dose of 0.4 mg/kg. Safety was assessed throughout the study, and the clinical effects were assessed based on modified observer’s assessment of alertness/sedation and bispectral index (BIS) monitor. Pharmacokinetic parameters were calculated.

Results: The rates of drug-related adverse reactions among the elderly groups were a little higher than that of the non-elderly, and were slightly higher in the elderly receiving 0.4 mg/kg compared with the elderly given lower doses. The pharmacokinetic characteristics of 0.4 mg/kg HSK3486 in the elderly and non-elderly were comparable. The time to recovery was similar in elderly 0.3 mg/kg, elderly 0.4 mg/kg and non-elderly 0.4 mg/kg groups. In the elderly 0.2 mg/kg group, the time to loss of consciousness was a little longer, and the time to recovery was shorter, relative to the other three groups.

Conclusions: Administration of 0.3 mg/kg to the elderly and 0.4 mg/kg to the non-elderly were similarly efficacious. A dose of HSK3486 of 0.3 mg/kg may be chosen for clinical use in elderly patients.

Factors Associated with Occurrence of Atelectasis during Sedation for Imaging in Pediatric Patients: A Retrospective Single Center Cohort Study

Sedation can induce atelectasis which may cause suboptimal image quality. This study aimed to identify factors associated with the occurrence of atelectasis during sedation for imaging in pediatric patients. Patients < 18 years who had undergone whole-body magnetic resonance imaging (MRI) under sedation with propofol or dexmedetomidine were included in this study. The development of atelectasis was visually and quantitatively assessed by coronal short tau inversion recovery images of the thoracic level. Multivariable logistic regression was performed to identify the independent factors associated with the development of atelectasis. Ninety-one patients were included in the analysis. In the multivariable analysis, administration of supplemental oxygen was the only factor significantly associated with the occurrence of atelectasis (adjusted odds ratio, 4.84; 95% confidence interval, 1.48-15.83; p = 0.009). Univariable analysis showed that the use of dexmedetomidine was associated with a lower incidence of atelectasis; however, this could not be verified in the multivariable analysis. Among the pediatric patients who had undergone imaging under sedation, additional oxygen supplementation was the only independent factor associated with atelectasis occurrence. A prospective clinical trial is required to identify the cause-effect relationship between oxygen administration and occurrence of atelectasis during sedation.

Pain Intensity at Injection Site during Esophagogastroduodenoscopy Using Long- and Medium-Chain versus Long-Chain Triglyceride Propofol: A Randomized Controlled Double-Blind Study

Background/Aims

The intensities of injection pain resulting from the use of long- and medium-chain triglyceride (LCT/MCT) propofol and conventional LCT propofol during esophagogastroduodenoscopy (EGD) have yet to be compared. We aimed to determine the pain intensity caused by different formulations of propofol and to evaluate the formulation that would be preferred by patients as a sedative agent during their next procedure.

Methods

This study was a single-center, randomized, controlled, and double-blind trial. Pain intensity was estimated 30 seconds after propofol injection by an examiner who was blinded to the group assignment using a numeric (0-10) pain rating scale (NPRS). After 1 week, the patients were asked whether they could recall the pain and were willing to receive the same agent for their next EGD.

Results

One hundred twenty-nine patients were randomly assigned to LCT/MCT or LCT group. Although there was no significant difference in pain incidence between the LCT/MCT and LCT groups (52.9% vs 65.6%, p=0.156), the pain intensity was significantly lower in the LCT/MCT group (NPRS median [interquartile range]; 1 (0-2) vs 2 (0-5), p=0.005). After 1 week, fewer patients in the LCT/MCT group recalled the pain (19.1% vs 63.9%, p<0.001) and more patients in the LCT/MCT group were more willing to use the same agent for their next procedure (86.8% vs 72.1%, p=0.048) than in the LCT group.

Conclusions

LCT/MCT propofol significantly reduced injection pain intensity compared to LCT propofol during EGD and preferred by patients as a sedative agent during their next EGD.

Intravenous Dexmedetomidine Administration Prior Anesthesia Induction With Propofol at 4°C Attenuates Propofol Injection Pain: A Double-Blind, Randomized, Placebo-Controlled Trial

Background: Propofol injection pain, despite various interventions, still occurs during the anesthesia induction and causes intense discomfort and anxiety in patients. This study aimed to explore the effect of intravenous dexmedetomidine on propofol injection pain prior to anesthesia induction with propofol at 4°C.

Methods: A total of 251 patients (American Society of Anesthesiologists I–II) who underwent oral and maxillofacial surgery were randomly assigned to a combination group (n = 63), lidocaine group (n = 62), dexmedetomidine group (n = 63), and placebo-control group (n = 63); they received 0.5 ug/kg dexmedetomidine prior to anesthesia induction with propofol at 4°C, 40 mg lidocaine, 0.5 ug/kg dexmedetomidine prior to anesthesia induction, and normal saline, respectively. Incidence of pain, pain intensity, and reaction to the pain stimulus were evaluated by using verbal categorial scoring (VCS), a numerical rating scale (NRS), and the Surgical Pleth Index (SPI), respectively. In addition, hemodynamic parameters such as heart rate (HR) and mean arterial pressure (MAP) were also measured. The VCS and NRS were evaluated at 5 s after propofol injection. In addition, SPI, HR, and MAP were evaluated at three time points (before anesthesia induction and 5 and 30 s after propofol injection).

Results: The incidence of pain in the combination group (51%) was significantly lower than that in the lidocaine group (71%), dexmedetomidine group (67%), or placebo-control group (94%) (p < 0.001). VCS and NRS scores in the combination group were also lower compared with the other three groups (p < 0.001), with no statistically significant differences between the lidocaine group and dexmedetomidine group (p > 0.05). The SPI of the combination group decreased significantly in comparison with the other three groups at 5 s after propofol injection (F = 96.23, p < 0.001) and 30 s after propofol injection (F = 4.46, p = 0.005). Further comparisons between HR and MAP revealed no significant differences across the groups (p > 0.05).

Conclusion: Because of the sedative nature of dexmedetomidine and analgesic effect of low temperature, this study showed that intravenous dexmedetomidine prior to anesthesia induction with propofol at 4°C is highly effective in attenuating the incidence and severity of pain during injection compared with lidocaine (40 mg), dexmedetomidine 0.5 ug/kg) and placebo. This approach was not associated with any anesthesia complications.

Clinical Trial Registration:ClinicalTrials.gov, identifier: ChiCTR-2000034663

Lidocaine for Reduction of Pain Induced by Propofol in a Tertiary Care Hospital: A Descriptive Cross-sectional Study

INTRODUCTION

Propofol is the most frequently used anaesthetic agent. Despite various anaesthetic benefits, propofol is not without side effects, pain on injection being the most common adverse effect. This study aimed to find the grade of pain reduced due to the injection of propofol after administration of lidocaine.

METHODS

A descriptive cross-sectional study was conducted from March 2015 to August 2015 in the operating theatre in a tertiary care hospital after taking ethical clearance with an ethical clearance from the Institutional Review Committee. A total of 64 participants fulfilling all inclusion criteria of both gender, age ranged from 16-65 years of American Society of Anesthesiologists physical status I and II ready for elective surgery under general anaesthesia with propofol pretreated with 60mg lidocaine with venous occlusion for one minute were observed. The pain was graded by the four-point scale (0=none, 1=mild, 2=moderate, 3=severe). Haemodynamic variables were measured until just before intubation.

RESULTS

In patients pretreated with lidocaine, no pain 56 (87.5%), mild pain 8 (12.5%) and moderate pain 0 (0%) were observed.

CONCLUSIONS

The grade of pain during injection of propofol was reduced in more than three-fourth of the patients after administration of pre-anaesthetic drug-like lidocaine.

De-mystifying the "Mixifusor"

Total intravenous anesthesia (TIVA) using a mixture of propofol and remifentanil in the same syringe has become an accepted technique in Pediatric Anesthesia. A survey by a group of respected UK anesthetists demonstrated a low incidence of serious complications, related to the pharmacology and dose of the drugs. However, a current guideline for the safe use of TIVA recommends against this practice. Pharmaceutical concerns include the physical stability of the emulsion when remifentanil is mixed with propofol; changes in drug concentration over time; nonuniform mixing of propofol and remifentanil; the risk of bacterial contamination; and the potential for drug administration errors. Propofol and remifentanil have markedly different pharmacokinetic profiles. When remifentanil is mixed with propofol and delivered as a target-controlled infusion (TCI) of propofol, remifentanil delivery is not target-controlled but passively follows the variable infusion rates calculated by the syringe driver to deliver predicted plasma or effect-site concentrations of propofol. The pharmacokinetic consequences can be illustrated using pharmacokinetic modeling similar to that used in TCI pumps. The clinical consequences reflect the dose-dependent pharmacodynamics of remifentanil. Increasing the target propofol concentration produces a rapid increase and peak in remifentanil concentration that risks apnea, bradycardia, and hypotension, especially with higher concentrations of remifentanil. The faster decline in remifentanil concentration with falling propofol concentrations risks inadequate narcosis and unwanted responses to surgical stimuli. Remifentanil delivery is inflexible and dosing cannot be adjusted to the clinical need and responses of individual patients. The medicolegal considerations are stark. In UK and EU Law, mixing propofol and remifentanil creates a new, unlicensed drug and the person mixing takes on the responsibilities of manufacturer. If a patient receiving anesthesia in the form of a mixed propofol-remifentanil infusion suffered a critical incident or actual harm, the clinician's practice may come under scrutiny and criticism, potentially involving a legal challenge and the Medical Regulator.

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.

Inhibition of Ligand-Gated TRPA1 by General Anesthetics

Several general anesthetics (GAs) produce pain or irritation upon administration, and this occurs predominantly through the activation of the nociceptive ion channel, transient receptor potential ankyrin type 1 (TRPA1). However, the effects of GAs on agonist-mediated TRPA1 activity are unclear. Here we show that a diverse range of noxious and non-noxious volatile anesthetics, at clinically relevant concentrations, inhibit ligand-activated TRPA1 currents. These effects are species-specific; GAs blocks rodent TRPA1 without affecting the Drosophila ortholog. Furthermore, propofol inhibits rodent but not human TRPA1. Analysis of chimeric TRPA1 proteins and mutagenesis combined reveals two amino acid residues located in the S5 domain, Ser876 and Thr877, that are critical for the inhibitory effects of isoflurane and propofol. Introduction of these residues into Drosophila TRPA1 confers anesthetic inhibition. Furthermore, several residues lining the presumptive binding pocket for noxious GAs are not required for the inhibitory effects of GAs. We conclude that anesthetics inhibit TRPA1 by interacting at a site distinct from the activation site. The inhibitory effects of GAs at TRPA1 may contribute to the diverse pharmacological action of these drugs. SIGNIFICANCE STATEMENT: We show that both noxious and non-noxious general anesthetics inhibit agonist-evoked transient receptor potential ankyrin type 1 (TRPA1) activity and identify critical amino acid residues located in the pore domain. Inhibition of TRPA1 may affect pain and vascular signaling during anesthesia.

Acceptability of intravenous propofol sedation for adolescent dental care

PURPOSE

Propofol is an intravenous anaesthetic agent commonly utilised in general anaesthesia, however in sub-anaesthetic concentrations can be utilised to provide sedation through automated dosing of target-controlled infusion (TCI). TCI has been shown to provide accurate and stable predicted plasma and effect-site concentrations of propofol. A four-part mixed-method prospective study was undertaken to evaluate the safety and patient acceptability of intravenous propofol sedation in adolescent patients requiring dental care. There is a paucity in the literature on patient-reported outcomes and patient safety in the management of adolescent patients for dental treatment.

METHODS

Demographics were recorded including age, gender, ASA Classification and Children's Fear Survey Schedule-Dental Subscale (CFSS-DS) completed pre-operatively. Behaviour ratings of the Frankl and Houpt scales were recorded followed by post-operative questionnaire and telephone consultation. Consultation was completed following the procedure to determine patient satisfaction, memory of the procedure and any reported side effects of treatment. Qualitative thematic analysis was utilised.

RESULTS

55 patients were recruited for the study, of which 49 (mean age 14.67 years) completed the sedation study and were treated safely with no post-operative complications. The mean lowest oxygen saturation was 98.12% SpO₂ (SD 2.6). Thematic analysis demonstrated positive patient-reported outcomes to IV sedation.

CONCLUSION

Propofol TCI sedation is an effective treatment modality for the management of dentally anxious adolescents as a safe alternative to general anaesthesia, allowing the opportunity for increased provision of treatment per visit on those patients with a high dental need. Further randomised controlled trials comparing propofol TCI to other pharmacological managements are required.

The propofol-sparing effect of intravenous lidocaine in elderly patients undergoing colonoscopy: a randomized, double-blinded, controlled study

Background

Propofol provides a prominent sedation effect in colonoscopy. However, anesthesia and sedation induced with propofol in the elderly might result in cardiopulmonary complications, especially when it is combined with opoids in the regimen. This study aimed to test the hypothesis that the addition of intravenous lidocaine to propofol-based sedation could decrease the overall propofol requirement in elderly patients during colonoscopy while the procedural sedation satisfaction and the hemodynamic stability were not compromised.

Methods

Ninety-two patients undergoing colonoscopy were randomly enrolled into lidocaine+propofol (L + P) group or normal saline+propofol (NS + P) groups. Subjects received intravenous bolus of 1.5 mg/kg lidocaine followed by 4 mg kg^− 1 h^− 1 lidocaine continuous infusion in L + P group or equivalent volumes of normal saline for boluses and infusion in NS + P group. Anesthesia was induced with 2.5 μg sufentanil followed by injection of 1.2 mg kg^− 1 propofol in all patients. A single supplemental bolus of 0.6 mg kg^− 1 propofol was administered whenever MOAA/S score > 1 or had body movement during the colonoscopy. The recorded primary endpoints included: the total amount of propofol administered during entire procedure, the supplemental amount of propofol after induction, and the frequencies of boluses of supplemental propofol.

Results

A total of 79 patients were included in the final analysis. Compared with NS + P group, the total amounts of propofol (induction plus supplemental) were no significant differences in L + P group; however, the required supplemental propofol was less (69.9 ± 39.2 mg vs. 51.5 ± 38.6 mg) (P = 0.039); the average frequencies of boluses of supplemental propofol given after induction were lower (2.1 ± 1.1 vs. 1.4 ± 0.9) (P = 0.003); the calculated “unit propofol” infusion rate was lower (0.18 ± 0.05 vs. 0.14 ± 0.04 mg kg^− 1 min^− 1) (P = 0.002).

Conclusions

The addition of intravenous lidocaine to propofol-based sedation resulted in a remarked reduction of supplemental propofol in the elderly during colonoscopy.

Trial registration

The present clinical trial was registered at http://www.chictr.org.cn on 11th March 2019 (registration No. ChiCTR1900021818).

Effect-site concentration of remifentanil for preventing propofol injection pain during induction of balanced anesthesia

Background

Despite various strategies designed for preventing pain from propofol injection, it is still common and distressing to the patients. The purpose of the present study was to investigate the adequate effect-site concentration (Ce) of remifentanil to prevent pain due to propofol injection.

Methods

A total of 160 adults scheduled for elective surgery were randomly assigned to one of four groups receiving normal saline (group S) or remifentanil at a Ce of 2 (group R2), 3 (group R3), or 4 ng/ml (group R4), administered via target-controlled infusion, followed by the injection of 2 mg/kg of propofol (delivered with 1% lipid propofol). The severity and incidence of injection pain were assessed on a four-point scale.

Results

The incidence of propofol injection pain was significantly lower in group R2, R3, or R4 than in group S (30%, 5%, or 2.5% vs. 70%, respectively). Moreover, the intensity of the pain was lesser in group R2, R3, or R4 than in group S. However, the incidence or severity of injection was not different between groups R3 and R4.

Conclusions

During the induction of balanced anesthesia using propofol injection, pretreatment with remifentanil at a target Ce of 3 ng/ml effectively reduced propofol injection pain in adults.

Drug selection for sedation and general anesthesia in children undergoing ambulatory magnetic resonance imaging

The demand for drug-induced sedation for magnetic resonance imaging (MRI) scans have substantially increased in response to increases in MRI utilization and growing interest in anxiety in children. Understanding the pharmacologic options for deep sedation and general anesthesia in an MRI environment is essential to achieve immobility for the successful completion of the procedure and ensure rapid and safe discharge of children undergoing ambulatory MRI. For painless diagnostic MRI, a single sedative/anesthetic agent without analgesia is safer than a combination of multiple sedatives. The traditional drugs, such as chloral hydrate, pentobarbital, midazolam, and ketamine, are still used due to the ease of administration despite low sedation success rate, prolonged recovery, and significant adverse events. Currently, dexmedetomidine, with respiratory drive preservation, and propofol, with high effectiveness and rapid recovery, are preferred for children undergoing ambulatory MRI. General anesthesia using propofol or sevoflurane can also provide predictable rapid time to readiness and scan times in infants or children with comorbidities. The selection of appropriate drugs as well as sufficient monitoring equipment are vital for effective and safe sedation and anesthesia for ambulatory pediatric MRI.

Efficacy of Intravenous Paracetamol in Combination with Lidocaine Pretreatment for Reducing Pain During Injection of Propofol

Introduction

The association of pain and discomfort of moderate to high severity and a high incidence with the intravenous (IV) administration of propofol is well known. Various physical and pharmacological methods are used to minimize propofol-induced pain, but the best intervention is still unknown. Therefore, our aim was to determine the analgesic efficacy of IV paracetamol when used in combination with lidocaine pretreatment in reducing propofol injection pain.

Materials and methods

This double-blind, randomized controlled trial was conducted after receiving the approval of our institutional research ethics board. A total of 74 patients were included after providing informed consent, and participants were placed into two equal groups: group A received IV paracetamol (1 g) in combination with lidocaine pretreatment prior to the injection of propofol, and group B received lidocaine pretreatment alone prior to propofol injection. After propofol injection, all participants were asked to evaluate pain on the visual analog scale.

Results

Patients who received the lidocaine-paracetamol combination reported significantly more pain-free responses (51.35%) than those from patients who received lidocaine pretreatment alone (8.11%; P<0.05). The analgesic efficacy of group A was positive in 36 patients (97.3%), and for group B, the analgesic efficacy was positive in 24 patients (64.9%).

Conclusion

The administration of IV paracetamol with lidocaine pretreatment was more effective than lidocaine pretreatment alone in reducing the pain caused by the injection of propofol. Physicians should consider using IV paracetamol in combination with lidocaine pretreatment when patients require IV propofol to ease patient suffering and reduce pain, which may help provide optimal patient care.

Comparison of Fentanyl, Remifentanil, Sufentanil and Alfentanil in Combination with Propofol for General Anesthesia: A Systematic Review and Meta-analysis of Randomized Controlled Trials

BACKGROUND

Opioid analgesics are commonly used along with propofol during general anesthesia. Due to the dearth of data on the quality of anesthesia achieved with this combination, the present meta-analysis was carried out.

METHODS

Electronic databases were searched for appropriate studies using a suitable search strategy. Randomized clinical trials comparing the combination of remifentanil/sufentanil/alfentanil with propofol with fentanyl and propofol, were included. The outcome measures were as follows: total propofol dose to achieve the desired general anesthesia; time of onset and duration of general anesthesia; depth of general anesthesia; and recovery time (time for eye-opening and time taken for extubation). Risk of bias was assessed and Forest plots were generated for eligible outcomes. The weighted mean difference [95% confidence intervals] was used as the effect estimate.

RESULTS

Fourteen studies were included in the systematic review and 13 were included in the metaanalysis. Statistically significant differences were observed for remifentanil in comparison to fentanyl when combined with propofol: Propofol dose (in mg) -76.18 [-94.72, -57.64]; time of onset of anesthesia (min) -0.44 [-0.74, -0.15]; time taken for eye-opening (min) -3.95 [-4.8, -3.1]; and time for extubation (min) -3.53 [-4.37, -2.7]. No significant differences were observed for either sufentanil or alfentanil about the dose of propofol required and due to scanty data, pooling of the data could not be attempted for other outcome measures for either sufentanil or alfentanil.

CONCLUSION

To conclude, we found that remifentanil has a statistically significant anesthetic profile than fentanyl when combined with propofol. Scanty evidence for both alfentanil and sufentanil precludes any such confirmation.

The analgesic efficacy and duration of lidocaine on vascular pain induced by hypertonic saline infusion: a double-blinded, randomized control trial

PURPOSE

To determine the analgesic efficacy and analgesic duration of lidocaine 20 mg and 40 mg on eliminating the vascular pain associated with hypertonic saline infusion.

METHOD

Patients who complained pain during infusion of hypertonic saline were randomized into three groups. They received normal saline (Group C), or lidocaine 20 mg (Group L20), or lidocaine 40 mg (Group L40). An electronic stopwatch was used to record the time to onset (T1) and the time to termination (T2) of the analgesic effect, and the analgesic duration (AD) was calculated as T2 - T1.

RESULTS

The incidence of pain elimination was significantly higher in both of the lidocaine groups (83.3 and 56.1% in Groups L40 and L20, respectively) than in the saline group (16.3%). Furthermore, lidocaine 40 mg was significantly more effective than 20 mg in eliminating the pain. The analgesic duration was significantly longer in Group L40 than in Group L20 (211.4 ± 50.2 vs. 130.3 ± 39.5 s, P < 0.001) and Group C (211.4 ± 50.2 vs. 45.1 ± 14.5 s, P < 0.001), and the analgesic duration in Group L20 was significantly longer than in Group C (P < 0.001). The incidence of transient tinnitus/dizziness was significantly higher in Group L40 than in Group L20 (19.0 vs. 2.4%, P < 0.05).

CONCLUSION

A single bolus of Lidocaine was effective in eliminating the pain induced by hypertonic saline infusion, but just for a short period of time. Lidocaine (without venous occlusion) only provides a short analgesic duration for local vein.

Clinical Pharmacokinetics and Pharmacodynamics of Propofol

Propofol is an intravenous hypnotic drug that is used for induction and maintenance of sedation and general anaesthesia. It exerts its effects through potentiation of the inhibitory neurotransmitter γ-aminobutyric acid (GABA) at the GABAA receptor, and has gained widespread use due to its favourable drug effect profile. The main adverse effects are disturbances in cardiopulmonary physiology. Due to its narrow therapeutic margin, propofol should only be administered by practitioners trained and experienced in providing general anaesthesia. Many pharmacokinetic (PK) and pharmacodynamic (PD) models for propofol exist. Some are used to inform drug dosing guidelines, and some are also implemented in so-called target-controlled infusion devices, to calculate the infusion rates required for user-defined target plasma or effect-site concentrations. Most of the models were designed for use in a specific and well-defined patient category. However, models applicable in a more general population have recently been developed and published. The most recent example is the general purpose propofol model developed by Eleveld and colleagues. Retrospective predictive performance evaluations show that this model performs as well as, or even better than, PK models developed for specific populations, such as adults, children or the obese; however, prospective evaluation of the model is still required. Propofol undergoes extensive PK and PD interactions with both other hypnotic drugs and opioids. PD interactions are the most clinically significant, and, with other hypnotics, tend to be additive, whereas interactions with opioids tend to be highly synergistic. Response surface modelling provides a tool to gain understanding and explore these complex interactions. Visual displays illustrating the effect of these interactions in real time can aid clinicians in optimal drug dosing while minimizing adverse effects. In this review, we provide an overview of the PK and PD of propofol in order to refresh readers' knowledge of its clinical applications, while discussing the main avenues of research where significant recent advances have been made.

Painful Recall in Elective Electrical Cardioversion with Propofol and the Need for Additional Analgesia

Introduction

Electrical cardioversion (ECV) is a short but painful procedure for treating cardiac dysrhythmias. There is a wide variation regarding the medication strategy to facilitate this procedure. Many different sedative techniques for ECV are described. Currently, the optimal medication strategy to prevent pain in ECV has yet to be established. The role for additional analgesic agents to prevent pain during the procedure remains controversial, and evidence is limited.

Methods

We conducted a prospective multicenter study to determine the incidence of painful recall in ECV with propofol as a sole agent for sedation, in order to assess the indication for additional opioids. In all patients, sedation was induced with propofol titrated till loss of eyelash reflex and nonresponsiveness to stimuli, corresponding to Ramsay Sedation Score level 5-6. ECV was performed with extracardiac biphasic electrical shocks. The primary outcome was painful recall of the procedure, defined as numeric pain rating scale (NRS) ≥ 1. NRS ≥ 4 is considered inadequately treated pain. Secondary outcome parameters were pain at the side of the defipads and muscle pain after ECV.

Results

A total of 232 patients were enrolled in this study. Six patients were excluded due to missing data or violation of study protocol. Three patients reported recall of the procedure, and one patient (0.4%) reported recall of severe pain during the procedure with NRS 7. Two patients (0.9%) reported recall of mild pain with NRS 1-3. Complete amnesia was observed in 223 patients (98.7%), with NRS 0. The mean of the total dose of propofol was 1.1 mg/kg. Fifteen patients (6.6%) experienced pain at the side of the defipads, and six patients (2.7%) complained of muscle pain after the procedure.

Conclusions

In this prospective multicenter study, propofol as a sole agent provided good conditions for ECV with a low incidence of recall. Effective sedation and complete amnesia was achieved in 98.7% of the patients, 0.4% of patients reported recall of severe pain during the procedure, and 0.9% of patients experienced mild pain during the ECV.

Risk factors for oxaliplatin-induced vascular pain in patients with colorectal cancer and comparison of the efficacy of preventive methods

Background

Vascular pain is a common adverse drug reaction in colorectal cancer patients receiving peripheral venous administration of oxaliplatin. The aim of this work was to identify risk factors for vascular pain, and to examine whether currently used treatments reduce its incidence.

Methods

We conducted a multicenter retrospective study in Japanese colorectal cancer patients receiving peripheral venous administration of oxaliplatin. The effects of various treatments (administration of analgesics, addition of dexamethasone to the infusion solution for pH adjustment, dilution of the infusion solution, or use of hot gel for warming the injection site) on the incidence of vascular pain were assessed. Risk factors for vascular pain were identified by multiple logistic regression analysis.

Results

One hundred and ninety patients who had received an oxaliplatin-containing regimen via a peripheral venous route were analyzed. None of the preventive methods examined significantly reduced the incidence of vascular pain. BMI (BMI < 22), clinical stage (I-III) and oxaliplatin dosage (130 mg/m² versus dose reduction) were identified as independent risk factors for development of vascular pain. The incidence of oxaliplatin-induced vascular pain was significantly higher in patients who had two or more risk factors.

Conclusions

BMI, clinical stage and oxaliplatin dosage were identified as independent predictive markers for oxaliplatin-induced vascular pain. Existing treatments for vascular pain are not effective in reducing its incidence.

Quantifying and presenting overall evidence in network meta-analysis

Network meta-analysis (NMA) has become an increasingly used tool to compare multiple treatments simultaneously by synthesizing direct and indirect evidence in clinical research. However, many existing studies did not properly report the evidence of treatment comparisons and show the comparison structure to audience. In addition, nearly all treatment networks presented only direct evidence, not overall evidence that can reflect the benefit of performing NMAs. This article classifies treatment networks into three types under different assumptions; they include networks with each treatment comparison's edge width proportional to the corresponding number of studies, sample size, and precision. In addition, three new measures (ie, the effective number of studies, the effective sample size, and the effective precision) are proposed to preliminarily quantify overall evidence gained in NMAs. They permit audience to intuitively evaluate the benefit of performing NMAs, compared with pairwise meta-analyses based on only direct evidence. We use four case studies, including one illustrative example, to demonstrate their derivations and interpretations. Treatment networks may look fairly differently when different measures are used to present the evidence. The proposed measures provide clear information about overall evidence of all treatment comparisons, and they also imply the additional number of studies, sample size, and precision obtained from indirect evidence. Some comparisons may benefit little from NMAs. Researchers are encouraged to present overall evidence of all treatment comparisons, so that audience can preliminarily evaluate the quality of NMAs.

Evaluation of efficacy of Valsalva maneuver for attenuating propofol injection pain: a prospective, randomized, single blind, placebo controlled study

Background

Pain on injection is a limitation with propofol use. The effect of the Valsalva maneuver on pain during propofol injection has not been studied. This maneuver reduces pain through the sinoaortic baroreceptor reflex arc and by distraction. We aimed to assess the efficacy of the Valsalva maneuver in reducing pain during propofol injection.

Methods

Eighty American Society of Anesthesiologists class I adult patients undergoing general anesthesia were enrolled and divided into two groups of 40 each. Group I (Valsalva) patients blew into a sphygmomanometer tube raising the mercury column up to 30 mmHg for 20 seconds, while Group II (Control) patients did not. Anesthesia was induced with 1% propofol immediately afterwards. Pain was assessed on a 10-point visual analog scale (VAS), where 0 represented no pain, and 10, the worst imaginable pain, and a 4-point withdrawal response score, where 0 represented no pain, and 3, the worst imaginable pain. Scores were presented as median (interquartile range).

Results

We analyzed the data of 70 patients. The incidence of pain was significantly lower in the Valsalva than in the control group (53% vs 78%, P = 0.029). The withdrawal response score was significantly lower in the Valsalva group (1.00 [0.00-1.00] vs 2.00 [2.00-3.00], P < 0.001). The VAS score was significantly lower in the Valsalva group (1.00 [0.00-4.00] vs 7.00 [6.25-8.00], P < 0.001).

Conclusions

A prior Valsalva maneuver is effective in attenuating injection pain due to propofol; it is advantageous in being a non-pharmacological, safe, easy, and time-effective technique.

Comparison the Effect of Granisetron and Dexamethasone on Intravenous Propofol Pain

Background:

The incidence of propofol injection pain during induction of general anesthesia varies from 28% to 90%. This prospective, randomized, double-blind, placebo-controlled study evaluated the effect of dexamethasone and granisetron for reducing the incidence and severity of propofol injection pain.

Materials and Methods:

A total of 227 female subjects received 5 mL of preservative-free saline, 1 mg granisetron (5 ml), or 0.15 mg/kg of dexamethasone (5 ml), intravenously, following exsanguination and occlusion of the veins of the arm. This was followed by a 0.5 mg/kg injection of propofol. Pain scores and intensity of pain recorded immediately following the injection of propofol. Hemodynamic parameters and O₂ sat were recorded 1, 3, 5, and 10 min after propofol injection.

Results:

The incidence pain following the injection of propofol was significantly decreased with both granisetron and dexamethasone (50.7% and 49.4%). Mean pain score in granisetron group was 3.16 ± 1.23, dexamethasone was 2.73 ± 1.03, and in saline group was 4.82 ± 1.73 (P = 0.001). Mean pain intensity in granisetron group was 1.16 ± 0.18, dexamethasone was 1.26 ± 0.14, and in saline group was 2.2 ± 0.99 (P = 0.001). There were no differences in either mean arterial pressure or O₂ Sate at any time point after drugs injection among the groups. There was a significant difference in pulse rate in third minutes between three groups and in the group who received granisetron was lesser (P = 0.04).

Conclusion:

Pretreatment with intravenous granisetron (1 mg) and dexamethasone (0.15 mg/kg) before injection of propofol is effective and safe in reducing the incidence and severity of pain due to propofol injection.

Propofol induces nuclear localization of Nrf2 under conditions of oxidative stress in cardiac H9c2 cells

Oxidative stress contributes to myocardial ischemia-reperfusion injury, which causes cardiomyocyte death and precipitate life-threatening heart failure. Propofol has been proposed to protect cells or tissues against oxidative stress. However, the mechanisms underlying its beneficial effects are not fully elucidated. In the present study, we employed an in vitro oxidative injury model, in which rat cardiac H9c2 cells were treated with H₂O₂, and investigated roles of propofol against oxidative stress. Propofol treatment reduced H₂O₂-induced apoptotic cell death. While H₂O₂ induced expression of the antioxidant enzyme HO-1, propofol further increased HO-1 mRNA and protein levels. Propofol also promoted nuclear localization of Nrf2 in the presence of H₂O₂. Knockdown of Nrf2 using siRNA suppressed propofol-inducible Nrf2 and expression of Nrf2-downstream antioxidant enzyme. Knockdown of Nrf2 suppressed the propofol-induced cytoprotection. In addition, Nrf2 overexpression induced nuclear localization of Nrf2 and HO-1 expression. These results suggest that propofol exerts antioxidative effects by inducing nuclear localization of Nrf2 and expression of its downstream enzyme in cardiac cells. Finally, we examined the effect of propofol on cardiomyocytes using myocardial ischemia-reperfusion injury models. The expression level of Nrf2 protein was increased at 15 min after reperfusion in the ischemia-reperfusion and propofol group compared with ischemia-reperfusion group in penumbra region. These results suggest that propofol protects cells or tissues from oxidative stress via Nrf2/HO-1 cascade.

Recent advances in intravenous anesthesia and anesthetics

Anesthesiology, as a field, has made promising advances in the discovery of novel, safe, effective, and efficient methods to deliver care. This review explores refinement in the technology of soft drug development, unique anesthetic delivery systems, and recent drug and device failures.

A prospective observational study of injection pain in children with medium plus long chain triglyceride and long chain triglyceride propofol premixed with lignocaine

Background and Aims:

Propofol injection pain is an unresolved problem in children. Although medium and long chain triglyceride (MCT-LCT) propofol has shown promising results in adults, its efficacy in children is not proven. In a prospective observational study the incidence and severity of pain with MCT-LCT and LCT propofol in children was compared.

Methods:

After obtaining approval from the Institutional Ethics Committee, 170 children (age group 6 months to 8 years) scheduled for various surgeries were included in this study. Following standard pre-medication, propofol 1% either LCT or MCT-LCT in a dose of 2–4 mg/kg along with preservative-free lignocaine (2% lignocaine 1 mg in propofol 10 mg) was administered. The primary objective was to study injection pain on scale of 0–6. For children ≤2 years doubling of motor event score (0–3) and for children >2 years, addition of motor (0–3) and verbalisation scores (0–3) were considered. Mann–Whitney U test was used for statistical analysis.

Results:

MCT-LCT group had lower incidence of pain (17 patients (20%) versus 35 patients (35.3%), P = 0.026) and severe pain (zero patients (0%) versus six patients (7.1%), P = 0.029) as compared to LCT group. MCT-LCT group had significantly lower mean rank of motor (79.65 versus 91.35), verbal (77.29 versus 90.79) and total score (77.76 versus 93.24) as compared to LCT group (P = 0.037, 0.002, and 0.009, respectively).

Conclusion:

MCT-LCT propofol is associated with significantly lower injection pain as compared to LCT propofol in children, when both are combined with lignocaine.

Hyoscine N-Butylbromide for Preventing Propofol Injection Pain: A Randomized, Placebo-Controlled and Double-Blind Study

OBJECTIVE

In this study, the aim was to investigate the effect of hyoscine N-butylbromide (HnBB) pretreatment on pain during propofol injection.

SUBJECTS AND METHODS

In this prospective, randomized, placebo-controlled and double-blind trial, 60 patients scheduled to undergo routine outpatient surgery under general anesthesia were randomly allocated to 2 groups, the HnBB (n = 30) and sodium chloride (n = 30) groups. Twenty seconds after the injection of 20 mg HnBB or 0.9 % sodium chloride, a 50-mg dose of propofol was injected in 2-3 s. Ten seconds later, the pain intensity was assessed using a 4-point scale: no pain (0), mild (1), moderate (2), and severe (3) pain. The Student t test was used for the analysis of parametric data and the Pearson χ2 test for categorical data.

RESULTS

The occurrence of pain in the HnBB group (43.3%) was significantly lower than the control group (73.3%) (p < 0.018). Of the 30 patients in each group, 10 in the control group and 3 in the HnBB group experienced severe pain (p = 0.001).

CONCLUSIONS

Pretreatment with 20 mg HnBB significantly reduced propofol injection pain compared to placebo.

Amelioration of Pain on Injection of Propofol: A Comparison of Pretreatment with Granisetron Vs Lignocaine

INTRODUCTION

Pain during propofol injection is a very commonly and frequently encountered event during induction of anaesthesia. A 5HT3 antagonists like granisetron are commonly used just prior to intravenous propofol as pre anaesthetic medication to prevent emesis in patients.

AIM

Comparison of pre treatment with granisetron versus lignocaine with respect to amelioration of pain induced by injection of propofol, in patient admitted for elective surgery with general anaesthesia.

MATERIALS AND METHODS

A randomized double blinded controlled study was conducted with patients divided into three groups with (n=30) in each group. Group I (the placebo group) received 2 ml of 0.9% normal saline, Group II received 2 ml of 1% lignocaine and Group III received 2 ml of granisetron (1 mg/ml) as pre treatment medication respectively. The patient's complain regarding pain on intravenous propofol administration was recorded using the Verbal Rating Score. Pulse, BP, SpO₂ were noted meticulously on three occasions-immediately after pre-treatment, injecting full dose of propofol (not for pain assessment) and after 10 minutes. The results were analysed using the null hypothesis and two sample t-tests.

RESULTS

It was observed and obvious that the relief of pain was significant (p<0.05) when granisetron or lignocaine was compared with the placebo group. But there was insignificant difference (p>0.05) when granisetron was compared with lignocaine in terms of relieve of pain induced by propofol.

CONCLUSION

It was concluded that parenteral administration of granisetron can be considered to be superior to lignocaine as pre treatment medication for pain relief after propofol injection along with the advantage of its anti-emetic effect.

Bayesian hierarchical models for network meta-analysis incorporating nonignorable missingness

Network meta-analysis expands the scope of a conventional pairwise meta-analysis to simultaneously compare multiple treatments, synthesizing both direct and indirect information and thus strengthening inference. Since most of trials only compare two treatments, a typical data set in a network meta-analysis managed as a trial-by-treatment matrix is extremely sparse, like an incomplete block structure with significant missing data. Zhang et al. proposed an arm-based method accounting for correlations among different treatments within the same trial and assuming that absent arms are missing at random. However, in randomized controlled trials, nonignorable missingness or missingness not at random may occur due to deliberate choices of treatments at the design stage. In addition, those undertaking a network meta-analysis may selectively choose treatments to include in the analysis, which may also lead to missingness not at random. In this paper, we extend our previous work to incorporate missingness not at random using selection models. The proposed method is then applied to two network meta-analyses and evaluated through extensive simulation studies. We also provide comprehensive comparisons of a commonly used contrast-based method and the arm-based method via simulations in a technical appendix under missing completely at random and missing at random.

Effective Dosage of Midazolam to Erase the Memory of Vascular Pain During Propofol Administration

Intravenous sedation with propofol is often administered to anxious patients in dental practice. Pain on injection of propofol is a common adverse effect. This study aimed to determine the age-adjusted doses of midazolam required to erase memory of vascular pain of propofol administration and assess whether the Ramsay Sedation Scale (RSS) after the pretreatment of midazolam was useful to predict amnesia of the vascular pain of propofol administration. A total of 246 patients with dental phobia requiring dental treatment under intravenous sedation were included. Patients were classified according to their age: 30s, 40s, 50s, and 60s. Three minutes after administration of a predetermined dose of midazolam, propofol was infused continuously. After completion of the dental procedure, patients were interviewed about the memory of any pain or discomfort in the injection site or forearm. The dosage of midazolam was determined using the Dixon up-down method. The first patient was administered 0.03 mg/kg, and if memory of vascular pain remained, the dosage was increased by 0.01 mg/kg for the next patient, and then if the memory was erased, the dosage was decreased by 0.01 mg/kg. The effective dosage of midazolam in 95% of each age group for erasing the memory of propofol vascular pain (ED95) was determined using logistic analysis. The accuracy of RSS to predict the amnesia of injection pain was assessed by receiver operating characteristic (ROC) analysis. The ED95 of midazolam to erase the memory of propofol vascular pain was 0.061 mg/kg in patients in their 30s, 0.049 mg/kg in patients in their 40s, 0.033 mg/kg in patients in their 50s, and 0.033 mg/kg in patients in their 60s. The area under the ROC curve was 0.31. The ED95 of midazolam required to erase the memory of propofol vascular pain demonstrated a downward trend with age. On the other hand, it was impossible to predict the amnesia of propofol vascular pain using the RSS.

Pain on propofol injection: Causes and remedies

Pain on propofol injection (POPI) is a minor problem that all anesthetists face every day. Introduction of several new formulations and hundreds of clinical trials have failed to find its remedy with just one intervention in all patients. This article highlights the causes of POPI and interventions that are used to eliminate this pain in current practice. Relevant articles from Medline and Embase databases were searched and included in this descriptive review with the following conclusions: (1) POPI is due to irritation of venous adventitia leading to release of mediators such as kininogen from kinin cascade. (2) When two or more drugs or measures are used, the incidence of POPI decreases considerably. Hence, the approach to eliminating POPI should be multimodal. (3) Any regimen that includes a drug having local anesthetic effect combined with central sedative/analgesic and rapid injection into a large vein should definitely reduce the risk of POPI to negligible levels.

Lornoxicam use to reduce the pain associated with propofol injection

Aim: To investigate the efficacy of lornoxicam in the prevention of the pain associated with propofol injection.

Material and method: Approval for this study was granted by the ethics committee of our hospital. Using a computer randomisation software, 120 patients undergoing elective surgery were assigned to four equal groups. In Group I (control group), immediately before anaesthesia induction, 10 ml of isotonic 0.9% NaCl solution (placebo) was administered intravenously (IV). In Groups II, III and IV, the same injection contained 2 mg, 4 mg and 8 mg of lornoxicam respectively. A tourniquet was then applied to the forearm for two minutes. Pain evaluation was made using a verbal pain score.

Results: Differences in pain severity scores were statistically significant between Groups I and II, Groups I and III, Groups I and IV and between Groups II and III (p < 0.05). However, no significant difference was determined between Groups III and IV (p = 0.401).

Conclusion: In all groups administered with lornoxicam, there was a significant reduction in the severity of pain associated with propofol injection, in comparison with the control group. Maximum effect is obtained with a dose of 4 mg.

Identification of a putative binding site critical for general anesthetic activation of TRPA1

General anesthetics suppress CNS activity by modulating the function of membrane ion channels, in particular, by enhancing activity of GABA_A receptors. In contrast, several volatile (isoflurane, desflurane) and i.v. (propofol) general anesthetics excite peripheral sensory nerves to cause pain and irritation upon administration. These noxious anesthetics activate transient receptor potential ankyrin repeat 1 (TRPA1), a major nociceptive ion channel, but the underlying mechanisms and site of action are unknown. Here we exploit the observation that pungent anesthetics activate mammalian but not Drosophila TRPA1. Analysis of chimeric Drosophila and mouse TRPA1 channels reveal a critical role for the fifth transmembrane domain (S5) in sensing anesthetics. Interestingly, we show that anesthetics share with the antagonist A-967079 a potential binding pocket lined by residues in the S5, S6, and the first pore helix; isoflurane competitively disrupts A-967079 antagonism, and introducing these mammalian TRPA1 residues into dTRPA1 recapitulates anesthetic agonism. Furthermore, molecular modeling predicts that isoflurane and propofol bind to this pocket by forming H-bond and halogen-bond interactions with Ser-876, Met-915, and Met-956. Mutagenizing Met-915 or Met-956 selectively abolishes activation by isoflurane and propofol without affecting actions of A-967079 or the agonist, menthol. Thus, our combined experimental and computational results reveal the potential binding mode of noxious general anesthetics at TRPA1. These data may provide a structural basis for designing drugs to counter the noxious and vasorelaxant properties of general anesthetics and may prove useful in understanding effects of anesthetics on related ion channels.

Efficacy of lidocaine on preventing incidence and severity of pain associated with propofol using in pediatric patients: A PRISMA-compliant meta-analysis of randomized controlled trials

BACKGROUND

Propofol injection pain was considered as one conundrum during clinical anesthesia. The systematic review about the effect of lidocaine in reducing injection pain among children has not been established. The aim of the study was to systematically evaluate the efficacy and safety of such intervention.

METHODS

The literature search was performed from the inception to the May 31, 2016 in PubMed, Ovid EMBASE, and Cochrane database. All randomized controlled trials that using lidocaine for propofol injection pain in children were enrolled. The primary outcome included the incidence of injection pain and the incidence of propofol injection pain in different degrees. The data were combined to calculate the relative ratio and relevant 95% confidence interval. A meta-analysis was performed following the guidelines of the Cochrane Reviewer's Handbook and the PRISMA statement.

RESULTS

Data from the included 11 studies indicated that the incidence of injection pain was lower in lidocaine group than the incidence in saline control group and in propofol lipuro (medium- and long-chain triglycerides) group (pain occurrence: 22.1% in lidocaine vs 66.8% in saline, RR with 95% 0.34 [0.26, 0.43], I = 38%; 30.5% in lidocaine vs 46.9% in propofol lipuro, RR with 95% 0.68 [0.46, 1.00], I = 9%). There was no difference between lidocaine and ketamine/alfentanil both in reducing pain occurrence and in reducing pain severity (pain occurrence: 29.7% in lidocaine vs 25.8% in ketamine, RR with 95% 1.47 [0.16, 13.43], I = 94%; 31.0% in lidocaine vs 30.7% in alfentanil, RR with 95% 1.01 [0.69, 1.46], I = 11%). And the reported side effects revealed that the safety of lidocaine in pediatric patients was acceptable.

CONCLUSION

Compared with ketamine and alfentanil, lidocaine would be served as one more effective treatment in consideration of its well-matched efficacy, acceptable accessibility, and reasonable safety. However, more high-quality evidences in pediatric patients are necessary.

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.

Propofol emulsion-free drug concentration is similar between batches and stable over time

Despite their widespread use for anesthesia and sedation, propofol emulsions have several unresolved issues, including pain on injection, stability concerns, and propensity to support bacterial growth. Pain accompanying a propofol injection has been attributed to the amount of free as opposed to emulsified propofol in the blood, which can differ with the formulation. Emulsions are inherently unstable and subject to several types of destabilization, but the actual mechanism may vary between formulations or batches. Free drug concentration and emulsion stability have not been widely studied between batches of propofol emulsions. Verifying whether batch-to-batch variability is a contributing factor to pain on injection or emulsion destabilization will help us better assess the causes and guide the design of future propofol formulations.

METHODS

Several samples of generic 1% propofol emulsion from various batches were compared. Free drug concentration was measured using an equilibrium dialysis method. Emulsion stability was evaluated by visible observation and by measuring droplet size distribution and polydispersity during shelf storage for up to 21 months.

RESULTS

Small differences in free drug concentration were observed between samples (10.6-16.7 μg/mL), but these differences were not statistically significant (p > 0.05). Emulsion droplet size (235.4-221.1 nm) and polydispersity (0.115-0.095) did not differ statistically over 21 months of storage. All batches were resistant to creaming and other destabilization mechanisms.

CONCLUSIONS

Batch-to-batch variability does not significantly alter the free drug concentration or stability of propofol formulations. If pain on injection of propofol is in fact related to the free propofol drug concentration, then it is unlikely that batch-to-batch variability causes any changes in pain on propofol injection.

A comparative study of attenuation of propofol-induced pain by lignocaine, ondansetron, and ramosetron

Background and Aims:

Propofol is widely used for induction of anaesthesia, although the pain during its injection remains a concern for all anaesthesiologists. A number of techniques have been adopted to minimise propofol-induced pain. Various 5-hydroxytryptamine-3 antagonists have shown to reduce propofol-induced pain. Hence, this placebo-controlled study was conducted to compare the efficacy of ondansetron, ramosetron and lignocaine in terms of attenuation of propofol-induced pain during induction of anaesthesia.

Methods:

Hundred and fifty adult patients, aged 18–60 years, posted for various elective surgical procedures under general anaesthesia were randomly assigned to three groups of 50 each. Group R received 0.3 mg of ramosetron, Group L received 0.5 mg/kg of 2% lignocaine and Group O received 4 mg of ondansetron. After intravenous (IV) pre-treatment of study drug, manual occlusion of venous drainage was done at mid-arm with the help of an assistant for 1 min. This was followed by administration of propofol (1%) after release of venous occlusion. Pain was assessed with a four-point scale. Unpaired Student's t-test and Chi-square test/Fisher's exact test were used to analyse results.

Results:

The overall incidence and intensity of pain were significantly less in Groups L and R compared to Group O (P ≤ 0.001). The incidence of mild to moderate pain in Groups O, R and L was 56%, 26% and 20%, respectively. The incidence of score ‘0’ (no pain) was significantly higher in Group L (76%) and Group R (72%) than Group O (34%) (P < 0.001).

Conclusion:

Pre-treatment with IV ramosetron 0.3 mg is equally effective as 0.5 mg/kg of 2% lignocaine in preventing propofol-induced pain and both were better than ondansetron.

Lipid composition and lidocaine effect on immediate and delayed injection pain following propofol administration

Background:

Propofol has been used for the induction and maintenance of anesthesia. However, patients experience vascular pain during its injection.

Aims:

The objective of this study was to compare the effect of the lipid type used in propofol preparations and that of lidocaine on the immediate and delayed vascular pain induced by propofol administration.

Materials and Methods:

In this double-blinded clinical study, 150 patients at American Society of Anesthesiologists level I-II were randomly divided into three equally sized groups. A propofol with medium and long-chain triglycerides (propofol-MCT/LCT) was administered to the first group. The second group received propofol containing propofol-LCT, and the third group received propofol-LCT and pretreatment lidocaine 20 mg. The incidence and the intensity of immediate (during injection) and delayed injection pain (after 20 s) were evaluated on a verbal analog scale (1–10) until patients’ unconsciousness.

Statistical Analysis:

Sample size was calculated with SigmaPlot version 12.5 software. Data were analyzed with Statistical Package for the Social Sciences (SPSS) version 16, one-way analysis of variance, and post-hoc Tukey. P < 0.05 was considered statistically significant.

Results:

The demographic parameters of the three groups were similar. The lidocaine group experienced the least immediate vascular pain. The intensity of pain was highest in the propofol-LCT group (P = 0.04). Additionally, the intensity of delayed pain was lowest in the propofol-MCT/LCT group (P = 0.01). The incidence of pain associated with the propofol administration was 26.5, 44, and 18%, respectively, in propofol-MCT/LCT, propofol-LCT, and lidocaine and propofol-LCT groups.

Conclusion:

The results indicate an effect of the lipid type on delayed pain reduction, especially propofol-MCT/LCT. On the other hand, the lidocaine decreases immediate propofol-LCT vascular pain.