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Propofol anesthesia in spontaneously breathing children undergoing magnetic resonance imaging: comparison of two propofol emulsions.

BACKGROUND: This study evaluated a propofol-based anesthesia regimen with spontaneous breathing in pediatric patients scheduled for magnetic resonance imaging (MRI). METHODS: In this prospective, randomized, double-blind study propofol formulated with long-chain triglycerides (LCT) and mixed medium-chain/long-chain triglycerides (MCT/LCT) were used. Ninety patients aged 2.4 months to 7.3 years were premedicated with intravenous midazolam. Lidocaine was injected prior to propofol to reduce injection pain. Anesthesia was induced and maintained by propofol. Glycopyrronium bromide was administered for saliva reduction. Hemodynamics, blood oxygen saturation and endtidal capnography were continuously monitored. All patients received additional oxygen. The aggregated propofol dose for induction and maintenance of anesthesia was analyzed for therapeutic equivalence. Incidence of injection pain, laboratory safety values, vital signs, and the adverse event profile were analyzed to compare tolerability and safety. RESULTS: Propofol anesthesia was safe and successful in all children. Both propofol formulations were equivalent regarding dose requirements (mean induction and maintenance doses for anesthesia 2.0-4.0 mg.kg(-1) and 6.0-8.8 mg.kg(-1).h(-1) respectively; aggregated doses 8-13.26 mg.kg(-1)). There were no differences in drug safety such as hemodynamics, spontaneous breathing, injection pain, and laboratory values. Duration of induction and of recovery from anesthesia were short and all examinations were completed with minimal interruption. CONCLUSIONS: Propofol-based short-term anesthesia was well suited for anesthesia during MRI procedures in the studied pediatric patients. There were no clinically relevant differences between the two propofol formulations.

Anesthesia, Intravenous↗

Pain on injection: a double-blind comparison of propofol with lidocaine pretreatment versus propofol formulated with long- and medium-chain triglycerides.

The incidence of pain on injection of propofol has been reported to be 70%. A new propofol formulation with a 10% emulsion of long- and medium-chain triglycerides (LCT/MCT) is associated with less pain on injection. Our goal was to compare the effect of propofol-LCT/MCT on the incidence of pain versus propofol with lidocaine 40 mg IV pretreatment injected as a Bier's block. Two hundred healthy women scheduled for ambulatory gynecological procedures were allocated to 1 of 2 groups in a randomized double-blind fashion. Group LIDO received lidocaine 2% 2 mL injected with a tourniquet 1 min before propofol 1% 2 mg/kg IV; group LCT/MCT received NaCl 0.9% 2 mL with tourniquet 1 min before propofol-LCT/MCT 1% 2 mg/kg IV. Spontaneous verbal expressions of pain, movement of hand, frowning, and moaning during the injection were recorded. The incidence and severity of pain were assessed 30 min and 6 h after surgery. Recall of pain was considered with a visual analog scale (VAS) score >1, and pain was graded as VAS 0-10. More women reported spontaneous verbal expression of pain with propofol-LCT/MCT (47% versus 24%; P = 0.0014; relative risk 1.61 [95% confidence interval, 1.22-2.13]). Among women with a painful injection, there was no difference after surgery regarding the intensity of pain or recall of pain. In contrast to previous reports, we found that propofol-LCT/MCT resulted in a more frequent incidence of pain than propofol 1% with IV lidocaine pretreatment. This may be due to the diversity of pain definitions used in studies or to the lack of premedication in our study.

Adolescent↗

Pain on injection of lipid-free propofol and propofol emulsion containing medium-chain triglyceride: a comparative study.

UNLABELLED: Pain on injection of propofol continues to be a problem for anesthesiologists. A lipid-free formulation of propofol and a propofol emulsion containing medium-chain triglyceride have become available in the Indian market. We performed this study to assess the pain on injection of propofol emulsion containing medium-chain triglyceride as the lipid carrier and lipid-free propofol formulation. One-hundred-thirty adult patients were randomly assigned to one of two groups: Group I received propofol emulsion containing medium-chain triglyceride and Group II received lipid-free propofol. One fourth of the total calculated induction dose was injected over 5 s in the largest vein on the dorsum of a hand. Pain was assessed using verbal response and behavioral signs. Both formulations caused pain on injection. However, the lipid-free propofol solution produced frequent (89%) and severe pain on injection compared with the emulsion containing medium-chain triglyceride (40%). IMPLICATIONS: Pain on injection of two formulations of propofol was compared. A lipid-free formulation produced more pain on injection as compared with the emulsion containing medium-chain triglyceride.

Adult↗

[Relationship between changes in estimated and measured blood concentrations of propofol and serum albumin concentration during propofol anesthesia: effects of intraoperative bleeding (a case report)].

We investigated the effect of intraoperative bleeding on the changes in estimated and measured blood concentrations of propofol, and the relationship between anesthetic effect of propofol and serum albumin concentration in a patient undergoing prostatectomy during propofol/epidural anesthesia. The rate of propofol infusion was titrated to keep the BIS value about 50. The estimated blood concentration of propofol calculated by ConGrase, a program for on-line simulation of blood propofol concentration, was monitored during anesthesia. Blood samples were obtained at nine points during surgery and the blood concentrations of propofol and albumin were measured postoperatively. When the amount of bleeding reached about 2000 mg, the difference between estimated and measured blood concentrations of propofol did not increase. As the serum albumin concentration decreased, the concentration of propofol to keep bispectral index about 50 decreased. This study suggests that the change in serum albumin concentration following intraoperative bleeding is an important factor in the anesthetic effect of propofol.

Aged↗

[Hemodynamic changes during slow induction of anesthesia using propofol and the effect of cardiac output on the propofol concentration].

This investigation assessed the hemodynamic changes during the slow induction of anesthesia using propofol, and evaluated the effects of cardiac output (CO) and other factors on the hypnotic dose of propofol, the time for hypnosis and the plasma propofol concentration. We studied 26 scheduled surgical patients and induced anesthesia with continuous infusion of propofol at the rate of 15 mg.kg-1.hr-1. The required dose of propofol and time for hypnosis were determined and the plasma concentration of propofol was measured after the administration of propofol 2 mg.kg-1. Cardiac output was determined by dye densitometry using indocyanine green 4 times during induction and CO did not show any significant changes during induction of anesthesia. Multiple linear regression analysis demonstrated that in addition to the age and total body weight, CO determined at achieving hypnosis was significantly related to the plasma concentration of propofol. Cardiac output might affect the pharmacokinetics of propofol during induction of anesthesia.

Adult↗

[The effect of propofol-ketamine anesthesia on hemodynamics and analgesia in comparison with propofol-fentanyl].

Propofol (Diprivan), a modern intravenous hypnotic, produces a reduction in both cardiac index (CI) and mean arterial pressure (MAP). Ketamine (Ketanest), a potent analgesic, in contrast, causes an increase in MAP and CI. The aim of the present study was to investigate whether the combination of propofol and ketamine can give better hemodynamic stability during the induction and maintenance of general anesthesia than propofol used with fentanyl, whose cardiodepressant actions may cumulate. METHODS. For induction of general anesthesia 10 patients (ASA I and II) each received 3-5 boluses of propofol (0.5 mg.kg-1 during 35 s until predetermined level of anesthesia was reached (stage D2/E0 according to [20]) followed by a continuous propofol infusion (0.120 mg.kg-1.min). Fentanyl 0.1 mg was administered to each patient in group A for induction of anesthesia and again if evident pain was present. In group B ketamine was given following a pharmacokinetic model based on computer-simulated calculation. After an initial bolus of 38 mg injected within 2 min further doses of 42 mg, 35 mg, 32 mg and 28 mg ketamine were administered over 30 min at a time. Signs of evident pain were treated by means of supplementary doses of 0.5 mg.kg-1. RESULTS. In both groups a moderate drop of MAP was observed after the induction of general anesthesia. Two patients in each group showed a distinct decrease in MAP (-32%). The heart rate dropped slightly (-9%) in group A, but did not change in group B. Following intubation the MAP rose by less in group A (+8%) than in group B (+21%). After the beginning of the operation the group treated with propofol/fentanyl showed major hemodynamic changes; in particular, bradycardia with less than 40 bpm was observed in more patients than in the propofol/ketamine group. Postoperatively, fewer patients in group B required rescue doses of analgesics (1 of 10) than these in group A (7 of 10), though vigilance was better in group B. DISCUSSION. The dose of ketamine administered during the induction of general anesthesia may have been not high enough to neutralize the cardiodepressant effect of propofol. But during the maintenance of anesthesia there was in fact better hemodynamic stability in group B than in group A as a result of the neutralization of opposing actions. Fentanyl even intensified the fall in MAP after propofol. Patients in group B showed better vigilance as well as better pain relief postoperatively. The population of the fentanyl group was obviously more deeply sedated and analgesia was still inadequate. In our study general intravenous anesthesia with propofol and ketamine offered the advantages of better analgesia, a higher state of vigilance and the absence of respiratory depression during the postoperative phase compared with the combination of propofol and fentanyl.

Analgesia↗

Target-controlled infusion during monitored anesthesia care in patients undergoing EUS: propofol alone versus midazolam plus propofol. A prospective double-blind randomised controlled trial.

BACKGROUND: It has been speculated that midazolam may be effective in reducing the required dose of propofol during sedation. AIM: To evaluate the sparing effect of midazolam during target-controlled propofol infusion. METHODS: Two hundred-seventy patients undergoing upper endoscopic ultrasound were randomised to receive sedation with propofol plus placebo (group A) or plus midazolam (group B). Outcome parameters were the procedure duration, the discharge time and the satisfaction of patients, operator and nurse about the quality of sedation. RESULTS: The mean propofol dose administered was 364+/-207 mg in group A and 394+/-204 mg in group B. Mean procedure duration (group A: 32+/-17 min, group B: 35+/-22 min) and discharge time (group A: 39+/-30 min, group B: 38+/-24 min) were similar in both groups. No severe complications were observed. The quality of sedation was judged satisfactory for all patients by both the endoscopist and the nurse assistant without any difference between the two groups. No patient remembered the procedure or reported it as unpleasant. CONCLUSIONS: Target-controlled propofol infusion provides safe and effective sedation; premedication with low dose of midazolam does not reduce the total amount of propofol administered. Further studies are needed to compare propofol alone with propofol co-administered with opioid.

Aged↗

Comparison of propofol with propofol-ketamine combination in pediatric patients undergoing auditory brainstem response testing.

OBJECTIVE: The aim of our study was to compare propofol with propofol-ketamine combination for sedation and also to compare related complications in children undergoing auditory brainstem response (ABR) testing. METHODS: Sixty ASA I-II patients aged between 1 and 13 years of age were sedated for ABR testing. Propofol 1.5mg/kg was used in group P (n=30), and ketamine 0.5 mg/kg+propofol 1.5 mg/kg, i.v., in group PK (n=30). Sedation levels of patients were maintained between scores 3 and 4 according to Ramsey sedation scores; when necessary, half of the starting drug dosage was administered for the maintenance of sedation. Side effects which occurred during or within the first 24h of the procedure were assessed. RESULTS: Additional dosage was needed for 21 cases in group P and eight cases in group PK (p=0.002). While oxygen desaturation and apnea were not observed in any of the patients in group PK, there were four patients (11.4%) with oxygen desaturation, and six (17.1%) with apnea in group P (p<0.05). CONCLUSIONS: In pediatric cases where ABR testing was applied, addition of low dose ketamine to propofol avoided the risk of respiratory depression due to propofol and lowered the need for additional dose of propofol. Therefore, the co-administration of propofol and ketamine appears to be a safe and useful technique for ABR testing.

Adolescent↗

A pharmacodynamic study of propofol or propofol and ketamine infusions in ponies undergoing surgery.

The pharmacodynamics of infusions of propofol alone (group 1) were compared with the pharmacodynamics of infusions of propofol and ketamine together (group 2) in eight ponies undergoing castration. Anaesthesia was induced with detomidine, 20 micrograms kg-1, followed by ketamine, 2.2 mg kg-1. Subsequently, a bolus dose of propofol, 0.5 mg kg-1, was administered intravenously to both groups, and an infusion of propofol was given for an average of 74 minutes to group 1, and an infusion of propofol and ketamine was given for 60 minutes to group 2. The mean (SD) infusion rates of propofol were 0.330 (0.050) mg kg-1 min-1 in group 1, and 0.124 (0.009) mg kg-1 in group 2, and the ketamine infusion rate was maintained constant at 40 micrograms kg-1 min-1. Arterial hypotension and marked respiratory depression were evident in some of the ponies receiving propofol alone, whereas in the ponies anaesthetised with propofol and ketamine, respiratory and cardiovascular parameters were well maintained. All the ponies in both groups recovered quickly from anaesthesia, with mean times to sternal recumbency and standing of 19.8 (8.0) minutes and 27.2 (7.4) minutes respectively for group 1 and 8.4 (3.2) min and 14.9 (10.1) minutes for group 2.

Analgesics↗

Remifentanil-propofol vs. sufentanil-propofol: optimal combinations in clinical anesthesia.

BACKGROUND: Two opioid regimens, computer-simulated to provide optimal general anesthesia in combination with propofol, were compared using clinical criteria. METHODS: Fifty patients undergoing thyroid surgery were blindly, prospectively and randomly allocated to receive either (a) i.v. remifentanil (1.5 micro g kg-1, followed by 0.2 micro g kg-1 min-1) or (b) i.v. sufentanil (0.2 micro g kg-1 followed by 0.2 micro g kg-1 h-1). Remifentanil infusion was stopped at the last skin suture. Sufentanil infusion was stopped 30 min before the end of surgery. Intravenous propofol was titrated to keep BIS at 50+/-5. Remifentanil and sufentanil groups were compared with regards to (a) propofol delivery, (b) hemodynamic and recovery variables, and (c) effect-site propofol levels during a steady-state period for effect-site remifentanil and sufentanil levels. P<0.05 was significant. RESULTS: Groups were similar in demographic data; types and durations of surgery; total propofol consumption; and response, extubation and emergence times. During the steady-state period for the opioid delivery, the remifentanil and sufentanil effect-site levels were 5.3 ng ml-1 and 0.18 ng ml-1, respectively (potency ratio=30). In both opioid groups, in accordance with previous computer-simulations, the effect-site propofol concentrations remained (a) within a narrow range unaffected by surgical stimuli, (b) significantly smaller in the remifentanil group than in the sufentanil group, but (c) smaller than expected from previous computer-simulations. More patients required ephedrine following induction of anesthesia in the remifentanil compared with the sufentanil group. CONCLUSIONS: The present clinical trial conducted in thyroid surgery is consistent with previous computer-simulated opioid-propofol combinations with respect to intraoperative and recovery variables. Effect-site propofol ranges were, however, lower than expected.

Adult↗

Propofol compared with general anesthesia for pediatric GI endoscopy: is propofol better?

BACKGROUND: The objective of this study was to compare the efficacy and safety of propofol and general anesthesia in children undergoing elective GI endoscopy. METHODS: The study design was prospective, randomized, and open label. Pediatric patients aged 2 to 21 years in whom elective GI endoscopy under general anesthesia was required were randomized to receive propofol or standard inhalational anesthesia. The parameters monitored in the 2 groups were (1) time until wake-up after completion of the procedure, and (2) total time for anesthesia and recovery. Adverse events during the procedures were noted with each agent. RESULTS: Fifty pediatric patients were recruited, 25 in each group. The mean (SD) time until wake-up in the propofol group was 29.92 (16.01) minutes and 18.52 (10.03) minutes in the anesthesia group, (p = 0.002). With stratification into 4 age groups, it was noted that the youngest children, those 2 to 5 years of age, took the longest to awaken with propofol compared with inhalational anesthesia, whereas in the other age groups the differences were not statistically significant. In contrast, the mean total time for anesthesia and recovery in the propofol group was 107.4 (30.14) minutes and 139 (7.61) minutes in the inhalational anesthesia group (p < 0.004). The total time for anesthesia and recovery was longest in the group 5 to 8 years of age who had inhalational anesthesia (p < 0.01). Changes in systolic and diastolic blood pressure occurred with equal frequency in both groups. Transient apnea was noted in 20% of patients receiving propofol. Restlessness and agitation occurred in 52% of patients receiving inhalational anesthesia compared with 8% in the propofol group (p = 0.001). CONCLUSIONS: Propofol, administered by an anesthesiologist, is an excellent and safe intravenous anesthetic agent for pediatric GI endoscopy.

Adolescent↗

The effects of plasma fentanyl concentrations on propofol requirement, emergence from anesthesia, and postoperative analgesia in propofol-nitrous oxide anesthesia.

UNLABELLED: To determine the effects of plasma fentanyl concentrations on intraoperative propofol requirements, emergence from anesthesia, and relief of postoperative pain, we studied 60 ASA physical status I and II patients undergoing spine fusion. The patients were randomly assigned to four study groups according to the expected intraoperative plasma fentanyl concentrations. Group I received an infusion of saline, and Groups II, III, and IV received fentanyl infusions to maintain the blood levels at 1.5, 3.0, and 4.5 ng/mL, respectively. An infusion rate of propofol was adjusted to keep the mean arterial pressure within 15% of the control value. Inspired nitrous oxide concentrations were maintained at 67%. The following were investigated in each group: 1) an average propofol infusion rate, 2) time to spontaneous eye opening and recovery of orientation (name, date, and place), and 3) total dose of fentanyl used for 24 h after admission to the postanesthetic care unit. Average propofol infusion rates were 10.1 +/- 2.5 (mean +/- SD), 7.5 +/- 1.2, 5.7 +/- 1.1, and 4.9 +/- 1.2 mg. kg(-1). h(-1), in Groups I, II, III, and IV, respectively. Groups receiving fentanyl infusion had significantly smaller infusion rates of propofol (P < 0.01) than the group receiving saline. Among the three fentanyl infusion groups, Group II (P < 0.01) had more than Groups III and IV. The time to spontaneous eye opening and the recovery of orientation were directly related to plasma fentanyl concentrations. The plasma fentanyl levels between Groups III and IV were the same. The total amount of IV patient-controlled analgesia fentanyl during postoperative 24 h increased significantly when the order of plasma fentanyl concentrations was reversed, 913.1 +/- 58.4, 553.4 +/- 129, 222.7 +/- 73.4, and 135.1 +/- 69.5 microg in Groups I, II, III, and IV, respectively. These results suggest that the addition of fentanyl infusions had ceiling effects that reduce the intraoperative propofol requirements according to the plasma fentanyl concentrations. The ceiling effect was demonstrated in the recovery of consciousness but not in the fentanyl requirements for postoperative analgesia. IMPLICATIONS: The addition of fentanyl, a potent opioid, reduced the intraoperative requirement of propofol, an IV anesthetic, in the order of the plasma fentanyl concentrations. The ceiling effects of fentanyl were demonstrated in the reduction of propofol requirements and recovery of consciousness but not in the fentanyl requirements for postoperative analgesia.

Adult↗

Synergistic sedation with oral midazolam as a premedication and intravenous propofol versus intravenous propofol alone in upper gastrointestinal endoscopies in children: a prospective, randomized study.

OBJECTIVES: The primary objective of the present study was to compare the required dose of intravenous (IV) propofol between group A (synergistic sedation with an oral dose of midazolam combined with IV propofol) and group B (IV propofol alone), in diagnostic upper gastrointestinal endoscopy (UGIE) in pediatric patients. The secondary objective was to compare the safety, the efficacy, the ease of IV line placement and the ease of separation from parents between the 2 groups. METHODS: Fifty-four consecutive children (aged 3 y or older) who underwent UGIE were randomly assigned to 1 of the 2 medication regimens. Patients in group A (n = 26, mean age: 8.1 y) received midazolam (0.5 mg/kg) orally. Thirty minutes after the midazolam dose was given, repeated IV doses of propofol 0.5 mg/kg were administered titrated to achieve the level of deep sedation. Patients in group B (n = 28, mean age: 9 y) received IV propofol alone with the same methodology and sedation end point. RESULTS: The mean dose (1.8 +/- 0.7 mg/kg) of propofol administered in group A patients was remarkably lower compared with that (2.9 +/- 0.9 mg/kg) of group B. Multivariate stepwise logistic regression analysis revealed that among sex, age, ASA grade and the type of sedation, the synergistic sedation was the only factor associated with the ease of IV line placement (chi(2) = 16.3, P < 0.001) and the ease of separation from parents (chi(2) = 41.6, P < 0.001). Additional multivariate stepwise logistic regression analysis revealed that among sex, age, ASA grade and the type of sedation, synergistic sedation was the only factor associated with a higher level of patient comfort (chi(2) = 35.5, P < 0.001). The recovery time was significantly shorter in group B patients (7.7 +/- 3.6 min) compared with that of group A (25.9 +/- 4.1 minutes) (P < 0.01). The 2 regimens were equally safe. CONCLUSIONS: Our data suggest that synergistic sedation with an oral dose of midazolam combined with propofol may benefit the children who undergo UGIE with regard to lower mean dose of propofol used, easier IV line placement, easier separation from the parents, less pain induced by the IV line placement and greater patient comfort.

Administration, Oral↗

Impact of the AEP-Monitor/2-derived composite auditory-evoked potential index on propofol consumption and emergence times during total intravenous anaesthesia with propofol and remifentanil in children.

BACKGROUND: The composite auditory evoked potential index (cAAI), derived from the AEP Monitor/2 (version 1.6; Danmeter A/S, Odense, Denmark) is a measure of the hypnotic component of general anaesthesia. The purpose of this study was to evaluate the impact of cAAI guidance on propofol consumption and emergence times in children receiving total intravenous anaesthesia (TIVA) with propofol and remifentanil. METHODS: Twenty children, aged 3-11 years, scheduled for strabismus repair under TIVA with propofol and remifentanil were enrolled. Remifentanil was given to all patients at a constant infusion rate of 0.3 microg kg(-1) min(-1) throughout the anaesthesia. Patients were randomly allocated to receive a continuous propofol infusion adjusted either according to a conventional clinical practice (Group C, n = 10) or guided by cAAI-monitoring (Group G, n = 10, target cAAI 25-35). All patients were connected to the AEP Monitor/2, but in group C the anaesthetist was blinded to cAAI values. Propofol consumption (mgkg(-1)h(-1)) and emergence times (min) were the primary and secondary outcome measures. RESULTS: Propofol consumption and emergence times (mean +/- SD) were significantly lower in group G compared to group C (Propofol: G: 4.2 +/- 1.7 vs. C 6.4 +/- 1.3 mg kg(-1) h(-1); P < 0.01; emergence times: G: 5.1 +/- 3.7 vs. C 13.2 +/- 8.2 min; P < 0.01). Intraoperative cAAI values (median [interquartile range]) were significantly higher in group G (23.9 [18-29.7]) than in group C (18.4 [16.0-22.1]; P < 0.01). Haemodynamic variables remained stable within age-related limits, and there were no observations of adverse events, especially no clinical signs of intraoperative awareness in any patient. CONCLUSION: Composite auditory evoked potential index monitoring during propofol/remifentanil-TIVA in children results in reduced propofol consumption and faster emergence.

Analysis of Variance↗

A combination of fentanyl-midazolam-propofol provides better intubating conditions than fentanyl-lignocaine-propofol in the absence of neuromuscular blocking agents.

BACKGROUND: The use of propofol and adjuvants such as opioids, benzodiazepines and local anaesthetic agents, may provide adequate conditions for tracheal intubation without the need for neuromuscular blocking agents. In this randomized, double-blind study, intubating conditions after induction of anaesthesia with propofol, midazolam and fentanyl were compared with those after propofol, lignocaine and fentanyl. METHODS: In 80 ASA I/II adult patients undergoing elective gynaecological surgery, intubating conditions were compared after induction of anaesthesia with a fentanyl 2 microg/kg, midazolam 0.03 mg/kg, propofol 2.5 mg/kg combination (group FMP) vs. a fentanyl 2 microg/kg, lignocaine 1.5 mg/kg, propofol 2.5 mg/kg combination (group FLP). Intubating conditions were assessed using a qualitative scoring system. RESULTS: Intubation was successful in all patients in group FMP and in 87.5% of patients in group FLP; (P= 0.021). Overall, intubating conditions were clinically acceptable in 77.5% and 55% of patients in group FMP and group FLP, respectively (P= 0.033). CONCLUSION: We conclude that the fentanyl, midazolam, propofol combination more reliably provides acceptable conditions for intubation than the fentanyl, lignocaine, propofol combination. Intubation was successful in all patients receiving the fentanyl, midazolam, propofol combination.

Adult↗

Complement activation by propofol and its effect during propofol anaesthesia.

We have examined whether propofol activates complement. In the first study, blood was mixed with saline, propofol or the lipid solvent for propofol, and the activated complement 3 (C3a) and 4 (C4a) concentrations in the supernatant were assayed. In the second study, blood and propofol were mixed with various levels of nafamostat mesilate (anti-complement agent) up to 0.3 mmol/l and the C3a was assayed. In the third study, the time course of plasma C3a concentration in patients during propofol anaesthesia was examined. The results showed that the lipid solvent activated complement and produced similar levels of C3a to propofol, probably via both the classical and alternative pathways. This activation was not inhibited by any of the nafamostat concentrations used. There was no significant change in plasma C3a concentration during propofol anaesthesia. These results suggest that C3a is generated by the lipid solvent, but its accumulation during propofol anaesthesia is minimal.

Adult↗

2,6 di-tert-butylphenol, a nonanesthetic propofol analog, modulates alpha1beta glycine receptor function in a manner distinct from propofol.

The anesthetic propofol (2,6 diisopropylphenol) mediates some of its effects by activating inhibitory chloride currents in the lower brainstem and spinal cord. The effects comprise direct activation of gamma-aminobutyric acid-A and glycine receptors in the absence of the natural agonist, as well as potentiation of the effect of submaximal agonist concentrations. Replacement of propofol's isopropyl groups by di-tert-butyl groups yields a compound without in vivo anesthetic effects. We have studied the effects of propofol and 2,6 di-tert-butylphenol on chloride inward currents via rat alpha1beta glycine receptors heterologously expressed in human embryonic kidney cells. Propofol, but not 2,6 di-tert-butylphenol, directly activated glycine receptors; half-maximal current activation was observed with propofol 114 +/- 27 microM. Both compounds potentiated the effect of a submaximal glycine concentration (10 microM) to a maximum value of 136% +/- 71% (propofol) and 279% +/- 109% (2,6 di-tert-butylphenol) of the response to glycine 10 microM. The 50% effective concentration for this effect was 12.5 +/- 6.4 microM and 9.4 +/- 10.2 microM for propofol and 2,6 di-tert-butylphenol, respectively. Propofol and its nonanesthetic structural analog do not differ in their ability to coactivate the glycine receptor but differ in their ability to directly activate the receptor in the absence of the natural agonist.

Algorithms↗