The Pharmacodynamic Effects of a Lower-Lipid Emulsion of Propofol: A Comparison with the Standard Propofol Emulsion

Correlation of Block Success with Perfusion Index Measurement in Cases of Pediatric Surgery Under Caudal Epidural Block Anesthesia

PURPOSE

One of the regional anesthetic procedures, caudal epidural block, is important for lower extremities surgeries in the pediatric patient population. The perfusion index (PI) value, which reflects vasomotor tone, can be used to indicate block success. The aim was to compare the role of perfusion index, heart rate, and mean arterial pressure in detecting the success of caudal epidural block and to investigate whether perfusion index was an earlier indicator in determining the success of the block in pediatric surgery cases.

DESIGN

A randomized controlled trial.

METHODS

The study included 58 patients, American Society of Anesthesiologists'classification 1, between the ages 1 and 6 years. In the left lateral decubitus posture, caudal epidural block was performed using a 23 or 25-gauge caudal needle and a dosage of 0.25% bupivacaine (1 mL/kg). At the 0, 1, 5, 7, 10, 15, and 20th minutes, peripheral oxygen saturation, heart rate, mean arterial pressure, and PI values were obtained using a probe attached to the first toe of the left foot. A successful caudal epidural block indication was defined as an increase of at least 100% in the PI value over the baseline value and a 15% decrease in mean arterial pressure and heart rate FINDINGS: PI represents the ratio of the photoplethysmography signal to pulsatile over nonpulsatile light absorbance. An increase in the PI value indicates that the block is effective. In the 20-minute follow-up period after caudal epidural block, there was at least a 100% increase in PI value in all of the patients at the seventh minute. An expected 15% reduction in mean arterial pressure was observed in 14.5% of the patients and an expected 15% reduction in heart rate was observed in 45.6% of the patients.

CONCLUSIONS

The results obtained from our study show that the increase in PI values is associated with caudal epidural block success. The PI value is more rapid, sensitive and objective than those produced by other parameters. Benefits include an earlier change in anesthesia management due to block failure and faster initiation to surgery, which reduces exposure to anesthetic chemicals.

Efficacy and safety of Ciprofol for procedural sedation and anesthesia in non-operating room settings

STUDY OBJECTIVE

Ciprofol, a novel intravenous anesthetic, provides rapid recovery in patients undergoing colonoscopy. We aimed to examine the efficacy and safety of ciprofol in comparison with propofol for sedation or anesthesia in non-operating room settings including endoscopic submucosal dissection, endoscopic retrograde cholangiopancreatography, and flexible bronchoscopy (FB).

DESIGN

Prospective, randomized, double-blind, parallel-group clinical trial.

SETTING

University-affiliated teaching hospital.

PATIENTS

We recruited 207 patients scheduled for an endoscopic procedure from October 2021 to December 2021.

INTERVENTIONS

Patients were randomized into three groups according to the dose during induction (n = 69 each): 1) ciprofol 6 mg/kg/h, 2) ciprofol 8 mg/kg/h, or 3) propofol 40 mg/kg/h. Ciprofol or propofol was administered throughout the procedure.

MEASUREMENTS

The primary outcome was the success rate of sedation or anesthesia for the procedures. Secondary outcomes included induction time, endoscope insertion time, recovery time, discharge time, incidence of drug-related adverse events (AEs), neurological and inflammatory outcomes.

MAIN RESULTS

The procedure success rates in the three groups were 100%. The induction time in the 6 (3.3 ± 1.0 min) and 8 mg/kg/h (2.9 ± 0.6 min) ciprofol groups was longer than that in the propofol group (2.5 ± 0.6 min) only in patients undergoing FB (p = 0.004). The time for patients to be fully alert and discharged from the post-anesthesia care unit was comparable across the three groups (p > 0.05). The incidence of drug-related AEs in the propofol and 6 and 8 mg/kg/h ciprofol groups was 84.1%, 76.8%, and 79.7%. No pain on injection was reported by ciprofol groups. Neurological outcomes and inflammatory responses were comparable among the three groups.

CONCLUSIONS

Ciprofol induced a level of sedation or anesthesia equivalent to that induced by propofol in non-operating room settings except for a prolonged induction time in patients undergoing FB. Ciprofol had a safety profile similar to that of propofol. No pain on injection was reported by ciprofol.

Multiparametric Monitoring of Hypnosis and Nociception-Antinociception Balance during General Anesthesia-A New Era in Patient Safety Standards and Healthcare Management

The development of general anesthesia techniques and anesthetic substances has opened new horizons for the expansion and improvement of surgical techniques. Nevertheless, more complex surgical procedures have brought a higher complexity and longer duration for general anesthesia, which has led to a series of adverse events such as hemodynamic instability, under- or overdosage of anesthetic drugs, and an increased number of post-anesthetic events. In order to adapt the anesthesia according to the particularities of each patient, the multimodal monitoring of these patients is highly recommended. Classically, general anesthesia monitoring consists of the analysis of vital functions and gas exchange. Multimodal monitoring refers to the concomitant monitoring of the degree of hypnosis and the nociceptive-antinociceptive balance. By titrating anesthetic drugs according to these parameters, clinical benefits can be obtained, such as hemodynamic stabilization, the reduction of awakening times, and the reduction of postoperative complications. Another important aspect is the impact on the status of inflammation and the redox balance. By minimizing inflammatory and oxidative impact, a faster recovery can be achieved that increases patient safety. The purpose of this literature review is to present the most modern multimodal monitoring techniques to discuss the particularities of each technique.

Design, Synthesis, and Activity Study of Water-Soluble, Rapid-Release Propofol Prodrugs

In this work, a series of water-soluble propofol prodrugs were synthesized, and their propofol release rate and pharmacodynamic characteristics were measured. We found that inserting glycolic acid as a linker between propofol and the cyclic amino acid accelerated the release of propofol from prodrugs into the plasma while preserving its safety. In animal experiments, prodrugs (3e, 3g, and 3j) were significantly better than fospropofol (the only water-soluble propofol prodrug that has been used clinically) in terms of safety, onset, and duration time of anesthesia. Their molar dose, onset time, and anesthesia duration time were comparable to those of propofol, helping to maintain the clinical benefits of propofol. The experimental results showed the potential of such compounds as water-soluble prodrugs of propofol.

Impact of Anesthetics on Human Neutrophil Function

Anesthetics are widely used drugs administered in a multitude of clinical settings. Their impacts on various functions of the immune system have been studied but are still not fully understood. Neutrophil granulocytes are a critical first-line host defense mechanism against infections and contribute to the inflammatory phase of wound healing, but dysregulated neutrophil activation can also precipitate perioperative organ injury. A better understanding of the interactions between common anesthetics and neutrophils may reveal considerations toward optimizing treatment of our most vulnerable patients in the intensive care unit and in the perioperative setting.

Novel propofol derivatives and implications for anesthesia practice

Propofol (2,6-diisopropylphenol) is the most commonly used intravenous agent for induction of anesthesia. It is also used for maintenance of anesthesia and sedation in both Intensive Care Units and outpatient procedural settings. Its success in the clinical setting has been a result of its rapid onset, short duration of action, and minimal side effects despite disadvantages associated with its oil emulsion formulation. Early attempts to alter the standard emulsion or to develop new formulations with cyclodextrins and micelles to resolve issues with pain upon injection, the need for antimicrobial agents, and possible hyperlipidemia have mostly failed. With these challenges in the foreground, attention has now shifted to the use of more prodrugs and exogenous alternatives, the success of which is yet to be determined. These new agents must offer significant clinical advantages over the well-entrenched, generic propofol oil emulsion to justify higher costs and to be well received in the increasingly cost-conscious healthcare marketplace.

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.

New medications and techniques in ambulatory anesthesia

Novel anesthetic and analgesic agents are currently under development or investigation to improve anesthetic delivery and patient care. The pharmacokinetic and analgesic profiles of these agents are especially tailored to meet the challenges of rapid recovery and opioid minimization associated with ambulatory anesthesia practice.

Injection pain of propofol in children: A comparison of two formulations without added lidocaine

Background:

Propofol emulsion in medium and long-chain triglycerides (MCT/LCT) has been reported to cause less injection pain than other propofol solutions in adult studies. The aim of this study was to compare the injection pain of two different propofol emulsions using two different pain scales on the pediatric population.

Materials and Methods:

100 children scheduled for general anesthesia were divided into two groups. Patients were randomly assigned to receive propofol LCT or propofol MCT/LCT. Assessment and evaluation of the Ontario Children's Hospital Pain Scale (mCHEOPS) and the Wong-Baker Faces Scale (WBFS) were performed at the start of the injection until the patients lose consciousness.

Results:

There were no significant differences between groups in terms of demographic data. According to the mCHEOPS scale, the pain incidence of propofol LCT was 5%, whereas for propofol MCT/LCT it was 15% (P < 0.05). According to the WBFS Pain Scale, the pain incidence of propofol LCT was 17%, whereas for propofol MCT/LCT it was 21% (P > 0.05).

Conclusions:

Propofol MCT/LCT does not decrease injection pain; contrary to the general assumption, it causes more pain than propofol LCT in children.

Caudal epidural block in children and infants: retrospective analysis of 2088 cases

BACKGROUND AND OBJECTIVES

Regional anesthesia is usually preferred as caudal block via the epidural space. However, the number of large-scale studies including pediatric caudal blocks is small. The objective of this study was to evaluate complications and side effects of local anesthetics and adjuvant drugs.

DESIGN AND SETTING

Retrospective, descriptive study of cases occurring during the period December 2007 to October 2009.

METHODS

Of 4815 medical records were screened, 2088 pediatric cases were identified and included in this study.

RESULTS

As a local anesthetic, we preferred mostly levobupivacaine in 1669 (79.9%) patients and bupivacaine in 419 (20.1%) patients. As adjuvant drug, we preferred mostly morphine (41 patients), fentanyl (7 patients) and adrenaline (6 patients) in 54 (2.5%) patients. For general anesthesia induction, we preferred mostly propofol (1996 patients, 94.2%); for maintenance, sevoflurane (1773 patients, 84.9%). For airway control, we preferred mostly the ProSeal laryngeal mask (PLMA), in 1008 (48.2%) patients. One thousand six hundred five (76.9%) patients were from outpatient clinics and 483 (23.1%) patients were from inpatient clinics. No permanent complication was encountered after caudal blocks.

CONCLUSION

We conclude that caudal epidural blocks are a safe and effective method for subumbilical day-case pediatric surgeries when performed by anesthetists.

The effect and optimal dose of sufentanil in reducing injection pain of microemulsion propofol

Background

Propofol is used as an induction and maintenance agent for general anesthesia but it can cause adverse reactions like hyperlipidemia, growth of microorganisms, and pulmonary embolisms. Microemulsion propofol was developed to avoid these side effects but incidence and severity of pain on injection is higher than with lipid emulsion propofol. We aimed to compare the effects of sufentanil in analgesic doses for reducing the injection pain of microemulsion propofol.

Methods

The candidates included eighty patients, 19-60 years old and ASA I-II. They were randomly classified into four groups and pretreated with normal saline, sufentanil 0.1 µg/kg, 0.2 µg/kg or 0.3 µg/kg before injection of microemulsion propofol. Five minutes after receiving pretreatment drug, 2 mg/kg of microemulsion propofol was injected and VAS was recorded.

Results

There were no significant differences in the incidence of injection pain among the groups. Severity of injection pain was significantly lower in the sufentanil 0.3 µg/kg group than normal saline and sufentanil 0.1 µg/kg group. Significant differences in blood pressure and heart rate were observed in sufentanil groups only after endotracheal intubation. One patient each in sufentanil 0.1 µg/kg and 0.3 µg/kg group experienced mild cough, one from sufentanil 0.3 µg/kg group experienced dizziness and another showed signs of hypoxia. One patient each in normal saline and sufentanil 0.1 µg/kg group showed clinical symptoms of phlebitis in the injection area.

Conclusions

Pretreatment with sufentanil 0.3 µg/kg reduced the severity of microemulsion propofol injection pain without increasing arterial blood pressure and heart rate after endotracheal intubation.

Pain on injection with microemulsion propofol

AIMS

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Development of a new generation of propofol

PURPOSE OF REVIEW

The current advance in development of a new generation of propofol and its clinical implications are reviewed.

RECENT FINDINGS

All currently available formulations of propofol have side effects related to propofol itself, as well as to the emulsion delivery systems. A search for better and safer propofol continues. Improvement of the emulsion delivery systems is one of approaches, which can be achieved by identifying better inactive components, enhancing stability, and applying new technologies such as nanotechnology. Modification of chemical structure is another approach, particularly with the development of propofol prodrugs.

SUMMARY

There is a continuous need to develop a better and safer propofol. The development of a new propofol should be focused on minimizing the unwanted side effects, while preserving the beneficial profiles. Hopefully, just such a new propofol will be available in the near future for clinical use.

Propofol: an immunomodulating agent

Propofol (2,6-diisopropylphenol) is a potent intravenous hypnotic agent widely administered for induction and maintenance of anesthesia and for sedation in the intensive care unit. Propofol is insoluble in water and therefore is formulated in a lipid emulsion. In addition, a preservative (ethylenediaminetetraacetic acid [EDTA] or sodium metabisulfite) is added to retard bacterial growth. Propofol has antiinflammatory properties, decreasing production of proinflammatory cytokines, altering expression of nitric oxide, and inhibiting neutrophil function. Propofol also is a potent antioxidant. The added preservatives have biologic activity; EDTA has antiinflammatory properties, whereas metabisulfite may cause lipid peroxidation. The antiinflammatory and antioxidant properties of propofol may have beneficial effects in patients with sepsis and systemic inflammatory response syndrome.

Changes in concentrations of free propofol by modification of the solution

Because free propofol is thought to be responsible for pain on injection, we investigated the changes in concentrations of free propofol by modifying two kinds of propofol products in a medium- and long-chain triglyceride (MCT/LCT) emulsion and in an LCT emulsion. The techniques used in this study were 1) mixing 2% lidocaine (10:1), 2) mixing 5% dextrose in acetated Ringer's solution to reduce pH (10:1), and 3) changing the temperature to 4 degrees , 20 degrees , and 36 degrees C. The propofol preparations were dialyzed for 24 h, and the receptor medium was analyzed using high-performance liquid chromatography. The concentration of free propofol in propofol MCT/LCT was significantly smaller by 30% than that in propofol LCT. Neither mixing lidocaine nor cooling reduced the concentrations of free propofol in both products, but the concentrations were reduced by a decrease in pH and by an increase in temperature. Because mixing lidocaine can induce instability in an emulsion of propofol and warming can rapidly induce microbial growth, injection of lidocaine before propofol administration is recommended to reduce the pain on injection. The concentrations of free propofol in propofol MCT/LCT were significantly smaller (by approximately 30%-45%) than those in propofol LCT during any situation in this study.

IMPLICATIONS

Neither mixing lidocaine nor cooling reduced the concentrations of free propofol in both products but the concentrations were reduced by a decrease in pH and by an increase in temperature. Propofol medium- and long-chain triglycerides had significantly smaller concentrations by approximately 30%-45% than those in propofol long-chain triglycerides during any situation in this study.

Adverse Events Associated with Sedatives, Analgesics, and Other Drugs That Provide Patient Comfort in the Intensive Care Unit

Since the 2002 publication of multidisciplinary clinical practice guidelines for intensive care unit (ICU) sedation and analgesia, additional information regarding adverse drug events has been reported. Our understanding of the risks associated with these sedative and analgesic agents promises to improve outcomes by helping clinicians identify and respond to therapeutic misadventures sooner. This review focuses on many issues, including the potentially fatal consequences associated with the propofol infusion syndrome, the evolving understanding of propylene glycol intoxication associated with parenteral lorazepam, new data involving high-dose and long-term dexmedetomidine therapy, haloperidol- and methadone-related prolongation of QTc intervals on the electrocardiogram, adverse events associated with atypical antipsychotics, and the potential for nonsteroidal antiinflammatory drugs to interfere with bone healing.

Recent advances in intravenous anaesthesia

Efforts to develop new hypnotic compounds continue, although several have recently failed in development. Propofol has been reformulated in various presentations with and without preservatives. Pharmacokinetic and pharmacodynamic differences exist between some of these preparations, and it is currently unclear whether any have substantial advantages over the original presentation. The use of target-controlled infusion (TCI) has been extended to include paediatric anaesthesia and sedation. Application of TCI to remifentanil is now licensed. Linking of electroencephalogram (EEG) monitoring to TCI for closed-loop anaesthesia remains a research tool, although commercial development may follow. The availability of stereoisomer ketamine and improved understanding of its pharmacology have increased non-anaesthetic use of ketamine as an adjunct analgesic. It may be useful in subhypnotic doses for postsurgical patients with pain refractory to morphine administration.