Blood Propofol Research Articles

Measured versus predicted blood propofol concentrations in children during scoliosis surgery.

Propofol anesthesia is preferred during scoliosis surgery because it suppresses evoked potential spinal cord function less than other drugs and better enables the detection of spinal cord ischemia. In this study, we determined the difference between the true and predicted blood propofol levels during target-controlled infusions in children during scoliosis surgery. Arterial blood propofol measured concentrations (Cm) were compared with predicted concentrations (Cp) approximately every 30 minutes during the maintenance phase of anesthesia in 20 children. Whole blood propofol concentrations were measured using a point-of-care blood propofol analyzer. Anesthesia management was not affected by the study. The median performance error, median absolute performance error, wobble, and divergence were calculated. Children were aged 9 to 17 years and weighed 26.5 to 95 kg. The Paedfusor model was used in 16 children and the Marsh model in 4 children. In 154 blood propofol measurements, the mean difference between the Cm and Cp was 1.5 µg·mL (limits of agreement, -1.4 to 4.5 µg·mL), and the mean performance error was 44.7% (limits of agreement, -40.1% to 130.2%). The median performance error and median absolute performance error for the whole group were 39.8% (range, -20.9% to 103.3%) and 39.8% (range, 20%-103.3%), respectively. The performance errors improved with increase in duration of infusion (divergence, -2.2 [range, -1.03 to 0.13]). Cm was almost always larger than Cp except in 2 children who had consistently lower Cm than Cp (lowest Cm(s) were 1.74 and 1.96 µg·mL when the Cp was 3 µg·mL); both had the Paedfusor model and their body weights were 28 and 33 kg. Propofol target-controlled infusion models had poor performance characteristics in children undergoing scoliosis surgery. Point-of-care propofol assay may enable adjustment of the infusion to better achieve the intended blood level.

Gas chromatograph–surface acoustic wave for quick real-time assessment of blood/exhaled gas ratio of propofol in humans

Although pilot studies have reported that exhaled propofol concentrations can reflect intraoperative plasma propofol concentrations in an individual, the blood/exhaled partial pressure ratio RBE varies between patients, and the relevant factors have not yet been clearly addressed. No efficient method has been reported for the quick evaluation of RBE and its association with inter-individual variables. We proposed a novel method that uses a surface acoustic wave (SAW) sensor combined with a fast gas chromatograph (GC) to simultaneously detect propofol concentrations in blood and exhaled gas in 28 patients who were receiving propofol i.v. A two-compartment pharmacokinetic (PK) model was established to simulate propofol concentrations in exhaled gas and blood after a bolus injection. Simulated propofol concentrations for exhaled gas and blood were used in a linear regression model to evaluate RBE. The fast GC-SAW system showed reliability and efficiency for simultaneous quantitative determination of propofol in blood (correlation coefficient R(2)=0.994, P<0.01) and exhaled gas (R(2)=0.991, P<0.01). The evaluation of RBE takes <50 min for a patient. The distribution of RBE in 28 patients showed inter-individual differences in RBE (median 1.27; inter-quartile range 1.07-1.59). Fast GC-SAW, which analyses samples in seconds, can perform both rapid monitoring of exhaled propofol concentrations and fast analysis of blood propofol concentrations. The proposed method allows early determination of the coefficient RBE in individuals. Further studies are required to quantify the distribution of RBE in a larger cohort and assess the effect of other potential factors. ChiCTR-ONC-13003291.

A comparison of the predictive performance of three pharmacokinetic models for propofol using measured values obtained during target‐controlled infusion

We compared the predictive performance of the existing Diprifusor and Schnider models, used for target-controlled infusion of propofol, with a new modification of the Diprifusor model (White) incorporating age and sex covariates. The bias and inaccuracy (precision) of each model were determined using computer simulation to replicate the infusion profiles in an earlier study of 41 patients undergoing surgery with propofol administered by target-controlled infusion and in which timed, measured blood propofol concentrations were available. Bias with the White model (5%) was significantly less (p < 0.0001) than with the Diprifusor (16%) or Schnider (15%) models. The White model showed a significant improvement in accuracy (inaccuracy 19%, p < 0.0001) relative to the Diprifusor (26%). Temporal changes were such that with all three models, bias differed at induction and recovery. None of the models accounted fully for the extent of inter-individual variation in propofol clearance, but the improved performance with the White model suggests it has merit.

Simple Voltammetric Method for the Determination of the Partition and Diffusion Coefficients in Solvent Polymeric Membranes

For feedback controlled monitoring of the popular anesthetic drug propofol we used an organic membrane-coated voltammetric sensor.1 The membrane coating prevents electrode fouling, and provides outstanding detection limit and selectivity for the voltametric working electrode that is adequate for continuous monitoring of propofol in whole blood in the presence of physiologically relevant interferences.The detection limit of the voltametric sensor is controlled by diffusion coefficient (D) and the concentration of the analyte in the membrane (cM), where cM is a function of membrane/solution partition coefficient (P). The selectivity of the membrane-coated sensor, on the other hand, depends on the partition coefficients of the analyte and interfering compounds.To assess the attainable detection limit and selectivity of the membrane coated sensor the diffusion and the partition coefficients have to be known. For the determination of the diffusion coefficients in the membrane it has been loaded with the analyte and the steady state current of a membrane coated planar electrochemical cell with a carbon fiber ultra microelectrode has been recorded in air (D=i/(4nFcMr)). By placing the membrane-coated planar electrochemical cell into a solution the concentration of the analyte in the membrane will be determined by its partition coefficients. From cyclic voltammetric experiments with the membrane-coated sensor in an analyte solutions one can calculate the partition coefficient of the analyte.In our contribution we discuss the unique advantages of the voltammetric method and report the partition coefficients of a variety of compounds (e.g., propofol, ascorbic acid, p-acetamido phenol) between plasticized PVC membranes and aqueous electrolytes as well as the diffusion coefficients of these compounds in the membranes.1. Kivlehan, F.; Garay, F.; Guo, J. D.; Chaum, E.; Lindner, E., Anal. Chem. 2012, 84 (18), 7670-7676.

Enhancing the sensitivity of the LC-MS/MS detection of propofol in urine and blood by azo-coupling derivatization

Propofol is a low-polarity, volatile molecule that is difficult for an electrospray ion source (ESI) to ionize in either negative ion mode (NIM) or positive ion mode (PIM), which hampers its detection via liquid chromatography-mass spectrometry. The aim of the present study was to use a new derivatization agent to improve ionization efficiency and to develop an efficient liquid chromatography-multiple mass spectrometry (LC-MS/MS) determination of propofol in urine and blood, taking advantage of an electrophilic aromatic substitution. An azo-coupling reaction with a diazonium salt from aniline was performed to introduce a protonation site into the molecule. The diazonium salt was generated by aniline in water solution by HCl and sodium nitrite; derivatization was achieved by stirring a mixture of the diazonium salt and propofol in sodium hydroxide solution for 30min below 5°C. A liquid-liquid extraction with dichloromethane and ethyl acetate was performed to obtain the azo derivative (molecular composition: C18H22ON2; molecular weight: 282Da) in high yield. The compound provided very high ionization yields in both PIM and NIM ESI, and the protonated or deprotonated molecule gave intense signals. The transitions m/z 283 → 77, 241 and m/z 281 → 176, 161 were chosen for the PIM and NIM, respectively, in order to develop quantitative methods of detecting propofol in urine and blood via triple-quadrupole LC-MS/MS. These methods proved to be highly sensitive, with limits of quantification of 0.4pg/mL and 0.1ng/mL obtained in the NIM when analyzing 1mL of urine and 100μL of blood, respectively.

A Remote-Controlled Airbag Device Can Improve Upper Airway Collapsibility by Producing Head Elevation With Jaw Closure in Normal Subjects Under Propofol Anesthesia.

Continuous maintenance of an appropriate position of the mandible and head purely by manual manipulation is difficult, although the maneuver can restore airway patency during sleep and anesthesia. The aim of this paper was to examine the effect of head elevation with jaw closure using a remote-controlled airbag device, such as the airbag system, on passive upper airway collapsibility during propofol anesthesia. Seven male subjects were studied. Propofol infusion was used for anesthesia induction and maintenance, with a target blood propofol concentration of 1.5–2 n}{}(mu )ng/ml. Nasal mask pressure (n}{}({P}_{text {N}})n) was intermittently reduced to evaluate upper airway collapsibility (passive n}{}({P}_{_{text {CRIT}}})n) and upstream resistance (n}{}({R}_{_{text {US}}})n) at three different head and jaw positions, jaw opening position in the supine position, jaw opening position in the sniffing position with 6-cm head elevation, and jaw closure at a 6-cm height sniffing position. The 6-cm height sniffing position with jaw closure was achieved by an airbag device that was attached to the subject’s head-like headgear. Patient demographics, n}{}({P}_{_{text {CRIT}}})n and n}{}({R}_{_{text {US}}})n in each condition were compared using one-way ANOVA with a post hoc Tukey test. n}{}({rm P}<0.05)n was considered significant. We also confirmed the effects of our airbag device on improvement of upper airway collapsibility in three obstructive sleep apnea patients in a clinical study. The combination of 6-cm head elevation with jaw closure using the air-inflatable robotic airbag system decreased upper airway collapsibility (n}{}({P}_{_{text {CRIT}}}sim -3.4)n-cm Hn}{}(_{2})nO) compared with the baseline position (n}{}({P}_{_{text {CRIT}}}sim -0.8)n-cm Hn}{}(_{2})nO, n}{}({P} = 0.0001)n). In the clinical study, there was improvement of upper airway obstruction in sleep apnea patients, including decreased apnea and hypopnea duration and increased the lowest level of oxygen saturation. We demonstrated that establishment of head elevation with jaw closure achieved by a remote-controlled airbag device using an inflatable airbag system can produce substantial decreases in upper airway collapsibility and maintain upper airway patency during propofol anesthesia and sleep.

Association of the CYP2B6 c.516G > T Polymorphism with High Blood Propofol Concentrations in Women from Northern Greece

Cytochrome P450 2B6 (CYP2B6) is responsible for the initial biotransformation of profol, an extensively metabolized intravenous anesthetic. In this study we examined the effect of the apparently functional CYP2B6 c.516G>T polymorphism on the distribution of propofol concentrations, quantified by GC/MS analysis following a single bolus dose, in the blood of 44 Greek women undergoing oocyte retrieval. Univariate analysis using age, height, weight and smoking status as covariates, as well as the Mann-Whitney non-parametric test, revealed a strong trend of association of the T allele with high propofol concentrations determined in whole blood, shortly after a single bolus dose. Propofol concentrations which were higher than one standard deviation of the mean were almost invariably associated with carriage of the T allele.

Effect of Target-Controlled Infusion of Propofol-Fentanyl versus Desflurane in Cirrhotic Patients Undergoing Major Hepatic Resection with Transoesophageal Doppler Monitoring A Randomized Control Study

Background and aim: The choice of anaesthetic agents is important for cirrhotics undergoing liver resection. Aim is to compare Target Controlled Infusion (TCI) Propofol-Fentanyl versus Desflurane (Des) on recovery, hemodynamics monitored with Transoesophageal Doppler (TED), the effect on hepatocellular, kidney functions and economics. Patients and methods: Prospective randomized controlled study, 50 patients (Child A) divided equally. In (Des) group induction with fentanyl (1microgram/kg), propofol (2 mg/kg) and rocuronium (1 mg/kg) and maintenance with Desflurane. In (TCI) group the Propofol blood target concentration (Ct) for induction was set at 4 μg/min and Fentanyl infusion was set at 3 μg/kg for 30 seconds , 2 μg/kg/h for 30 min, 1.5 μg/kg/h from 31-150 min, and 1 μg/kg/h until 30 min before end. Both propofol and fentanyl maintained with Navigator pharmacokinetic software and Entropy guidance. TED, urinary micro albuminurea (microalb), blood Glutathione-S-transferase (GST) were monitored. Results: Extubation time prolonged with TCI vs. Des (15.2 ± 2.6 vs. 9.7 ± 1.5 min respectively, (P 0.05), (Microalb. 17.7 ± 2.5 vs. 18.64 ± 1.19, (μgm/ml) respectively, P>0.05). Des more economic than TCI (33.5 ± 8.2 vs. 69.1 ± 8.1 US Dollars), (P< 0.05) respectively during same surgical time and with comparable hemoglobin concentrations. Conclusion: Recovery was enhanced better with Desflurane. TED monitoring demonstrated a significant preservation of SVR and MABP post-resection with Des vs. TCI. Neither was superior to the other with respect to liver and kidney functions. Further studies on a larger scale are recommended.

Relationship between blood levels of propofol and recovery of memory in electroconvulsive therapy

Memory impairment is a potential major adverse effect of electroconvulsive therapy (ECT). Some reports have suggested that propofol, an intravenous anesthetic widely used for general anesthesia in ECT, can minimize adverse effects on memory and cognitive function following ECT. The relation between propofol blood level during ECT and memory impairment after the procedure is unknown. We aimed to determine the relation between predicted blood level of propofol administered by target-controlled infusion during ECT and memory impairment after the procedure. Thirty-six patients who underwent a total of 260 series of ECT were enrolled as subjects. Anesthesia was induced with intravenous injection of propofol with a target-controlled infusion pump for predicting blood levels. Orientation and memory testing were performed after completion of ECT. In a subsequent analysis, subjects were divided into early memory recovery (n = 195) and late memory recovery (n = 65) groups. Likewise, for orientation testing,subjects were divided into early recovery (n = 193) and late recovery (n = 67) groups. In both groups, predicted blood propofol levels, total propofol dose, and other variables, such as number of ECT treatments, stimulus energy volume, and spike and slow wave time, were determined for comparison. Predicted blood propofol levels and propofol total dose were significantly higher in the early memory recovery group, while no significant differences were observed for the other variables. As for orientation, there were no significant differences between the early and late orientation recovery groups. Our data shows that the predicted blood propofol levels and the total dose influences memory impairment after the ECT.

A study of analytical methods for the determination of propofol in blood

Propofol (2,6-diisopropylphenol) is a commonly used short-acting intravenous anesthetic agent. However, because of the risk of drug abuse and propofol related death, in Korea propofol is a controlled drug. In this review, the analytical methods using liquid chromatography (LC), gas chromatography/mass spectrometry, or LC coupled with tandem mass spectrometry to detect and quantify propofol or its metabolites in blood were described. The validation data for the analytical methods and propofol concentrations in the blood were reviewed.

Impact of propofol on mid-latency auditory-evoked potentials in children

Propofol is increasingly used in paediatric anaesthesia, but can be challenging to titrate accurately in this group. Mid-latency auditory-evoked potentials (MLAEPs) can be used to help titrate propofol. However, the effects of propofol on MLAEP in children are unclear. Therefore, we investigated the relationship between propofol and MLAEP in children undergoing anaesthesia. Fourteen healthy children aged 4-16 yr received anaesthesia for elective surgery. Before surgery, propofol was administered in three concentrations (3, 6, 9 µg ml(-1)) through a target-controlled infusion pump using Kataria and colleagues' model. MLAEPs were recorded 5 min after having reached each target propofol concentration at each respective concentration. Additionally, venous propofol blood concentrations were assayed at each measuring time point. Propofol increased all four MLAEP peak latencies (peaks Na, Pa, Nb, P1) in a dose-dependent manner. In addition, the differences in amplitudes were significantly smaller with increasing propofol target concentrations. The measured propofol plasma concentrations correlated positively with the latencies of the peaks Na, Pa, and Nb. Propofol affects MLAEP latencies and amplitudes in children in a dose-dependent manner. MLAEP measurement might therefore be a useful tool for monitoring depth of propofol anaesthesia in children.

Determination of breath isoprene allows the identification of the expiratory fraction of the propofol breath signal during real-time propofol breath monitoring

Real-time measurement of propofol in the breath may be used for routine clinical monitoring. However, this requires unequivocal identification of the expiratory phase of the respiratory propofol signal as only expiratory propofol reflects propofol blood concentrations. Determination of CO2 breath concentrations is the current gold standard for the identification of expiratory gas but usually requires additional equipment. Human breath also contains isoprene, a volatile organic compound with low inspiratory breath concentration and an expiratory concentration plateau. We investigated whether breath isoprene could be used similarly to CO2 to identify the expiratory fraction of the propofol breath signal. We investigated real-time breath data obtained from 40study subjects during routine anesthesia. Propofol, isoprene, and CO2 breath concentrations were determined by a combined ion molecule reaction/electron impact mass spectrometry system. The expiratory propofol signal was identified according to breath CO2 and isoprene concentrations and presented as median of intervals of 30s duration. Bland-Altman analysis was applied to detect differences (bias) in the expiratory propofol signal extracted by the two identification methods. We investigated propofol signals in a total of 3,590 observation intervals of 30s duration in the 40 study subjects. In 51.4% of the intervals (1,844/3,590) both methods extracted the same results for expiratory propofol signal. Overall bias between the two data extraction methods was -0.12ppb. The lower and the upper limits of the 95% CI were -0.69 and 0.45ppb. Determination of isoprene breath concentrations allows the identification of the expiratory propofol signal during real-time breath monitoring.

Safety and Effectiveness of Low-Dose Propofol Sedation During and After Esophagogastroduodenoscopy in Child A and B Cirrhotic Patients

Effective and safe sedation for patients with liver cirrhosis is problematic. To examine the safety and effectiveness of low-dose propofol sedation during and after esophagogastroduodenoscopy (EGD) in cirrhotic patients. Study 1 was a prospective study in cirrhotic patients who underwent diagnostic EGD under propofol sedation. Propofol was given by bolus injection with an age-adjusted standard protocol consisting of 40 mg for patients <70 years, 30 mg for patients aged 70-89 years; additional injections of 20 mg propofol were given up to a maximum of 120 mg. The principal parameter was the occurrence of adverse events within 24 h after EGD. Secondary parameters included successful procedures, complications, and full recovery within 60 min. In Study 2, the residual effects of propofol were evaluated using a driving simulator and blood propofol concentrations in a subset of cirrhotic patients undergoing EGD and compared with healthy individuals. The principal parameter was driving ability. Study 1: Consecutive cirrhotic patients were entered and all 163 successfully completed EGD. The mean dose of propofol was 46 mg (range 30-120 mg). No complications occurred. Full recovery had occurred in 100 % 60 min after the procedure. No adverse events occurred within 24 h after EGD. Study 2: There were no significant differences in blood propofol levels between cirrhotic patients (n = 21) and healthy individuals (n = 20) after sedation. In cirrhotic patients, there was no deterioration in driving ability as compared with healthy individuals. Low-dose propofol sedation provided safe and effective sedation for EGD in cirrhotic patients with rapid recovery.

Prospective randomised comparison of Marsh and Schnider pharmacokinetic models for propofol during induction of anaesthesia in elective cardiac surgery

Haemodynamic stability during induction is a cornerstone of cardiac anaesthesia. The evaluation of pharmacokinetic models for propofol during induction is lacking. To compare haemodynamics during cardiac anaesthesia induction with two pharmacokinetic models. Randomised controlled trial. Department of Cardiothoracic Surgery, São João Hospital; July to December 2010. Ninety consecutive elective adult cardiac surgical patients. Random assignment to effect-site target-controlled infusion by Marsh (n = 45) or Schnider (n = 45) pharmacokinetic models with an equilibration constant of 1.2 min(-1) adapted to Marsh's model. Invasive blood pressure measurements, propofol dose, and bispectral index (BIS) were recorded. After an initial target concentration of 1.5 μg ml(-1), concentrations were upward-titrated in 0.5 μg ml(-1) increments until the BIS was <50. No differences were observed between Marsh and Schnider models in required propofol dose (0.99 ± 0.26 vs. 0.93 ± 0.31 mg kg(-1), P = 0.322), decrease in mean blood pressure (25 ± 13 vs. 22 ± 14%, P = 0.192) or the need for vasopressors (20 vs. 24%, P = 0.800), but the use of the Marsh model resulted in a lower predicted effect-site concentration (2.3 ± 0.4 vs. 2.7 ± 0.6 μg ml(-1), P = 0.006) and shorter time to induction (296 ± 59 vs. 338 ± 87 s, P = 0.024). There was a greater decrease in mean blood pressure in older patients (>60 years; 29 ± 10 vs. 22 ± 11%, P = 0.004) irrespective of model, but obese (BMI ≥30 kg m(-2)) and nonobese patients did not differ. Decrease in mean blood pressure. In effect-site targeting with a 1.2 min(-1) equilibration constant, Marsh's model is comparable to Schnider's during induction of anaesthesia.

Journal-related Activities and Other Special Activities at the 2012 American Society of Anesthesiologists Annual Meeting

Journal-related Activities and Other Special Activities at the 2012 American Society of Anesthesiologists Annual Meeting

Comparative canine Pharmacokinetics–Pharmacodynamics of Fospropofol Disodium Injection, Propofol Eemulsion, and Cyclodextrin-Enabled Propofol Solution Following Bolus Parenteral Administration

The pharmacokinetics and pharmacodynamics of fospropofol (FP) disodium injection, propofol emulsion (PE), and cyclodextrin-enabled propofol (CDP) solution following bolus parenteral administration in dogs was evaluated. Three healthy male beagle dogs were treated in a three-way cross-over study (14 day washout period) with 6 mg/kg propofol equivalents. Blood samples were collected predose and at 16 points postdose through 1440 min and analyzed for propofol and FP, when appropriate. From 5 min predose to 30 min postdose, brain electrical activity [electroencephalography (EEG)] was recorded and analyzed by power spectrum analysis techniques. Each formulation appeared to be well tolerated with transient discomfort observed in the PE and CDP animals and minor excitability in the FP animals prior to loss of consciousness. Blood propofol followed three-compartment pharmacokinetic behavior and derived parameters were not statistically different except for elimination half-life from the CDP formulation and onset, and duration of anesthesia from the FP formulation. The effect site concentrations at 50% the maximum EEG effect for the FP and CDP formulations were approximately one-half that of the PE formulation. Onset and duration of anesthesia are correlated with modeled effect site propofol concentrations. The implications of formulation on pain on injection and propofol activity are discussed.

Toward Feedback-Controlled Anesthesia: Voltammetric Measurement of Propofol (2,6-Diisopropylphenol) in Serum-Like Electrolyte Solutions

Propofol is a widely used, potent intravenous anesthetic for ambulatory anesthesia and long-term sedation. The target steady state concentration of propofol in blood is 0.25-10 μg/mL (1-60 μM). Although propofol can be oxidized electrochemically, monitoring its concentration in biological matrixes is very challenging due to (i) low therapeutic concentration, (ii) high concentrations of easily oxidizable interfering compounds in the sample, and (iii) fouling of the working electrode. In this work we report the performance characteristics of an organic film coated glassy carbon (GC) electrode for continuous monitoring of propofol. The organic film (a plasticized PVC membrane) improved the detection limit and the selectivity of the voltammetric sensor due to the large difference in hydrophobicity between the analyte (propofol) and interfering compounds of the sample, e.g., ascorbic acid (AA) or p-acetamidophenol (APAP). Furthermore, the membrane coating prevented electrode fouling and served as a protective barrier against electrode passivation by proteins. Studies revealed that sensitivity and selectivity of the voltammetric method is greatly influenced by the composition of the PVC membrane. The detection limit of the membrane-coated sensor for propofol in PBS is reported as 0.03 ± 0.01 μM. In serum-like electrolyte solutions containing physiologically relevant levels of albumin (5%) and 3 mM AA and 1 mM APAP as interfering agents, the detection limit was 0.5 ± 0.4 μM. Both values are below the target concentrations used clinically during anesthesia or sedation.

Real time monitoring of propofol blood concentration in ponies anaesthetized with propofol and ketamine

This study examined the pharmacokinetics of propofol by infusion in ponies using an analyser for the rapid measurement of propofol concentrations. The analyser (Pelorus 1000; Sphere Medical Ltd., Cambridge, UK) has a measurement cycle of approximately five minutes. Ten Welsh-cross ponies (weighing 135-300 kg) undergoing minor procedures were studied after premedication with acepromazine 0.03 mg/kg and detomidine 0.015 mg/kg. Anaesthesia was induced with ketamine 2 mg/kg and diazepam 0.03 mg/kg, and maintained with an infusion of propofol at an initial rate of 0.16 mg/kg/min for the first thirty minutes, after a bolus of 0.3 mg/kg; and ketamine by infusion (20-40 μg/kg/min). Blood samples (<2 mL) were collected prior to, during and after the infusion, and on assuming standing position. Anaesthesia was uneventful; with the duration of infusion 31-89 min. Blood propofol concentrations during the infusion ranged between 1.52 and 7.65 μg/mL; pseudo-steady state concentrations 3.64-6.78 μg/mL, and concentrations on assuming standing position 0.75-1.40 μg/mL. Propofol clearance and volume of distribution were 31.4 (SD 6.1) mL/min/kg and 220.7 (132.0) mL/kg, respectively. The propofol analyser allows titration of propofol to a given concentration; and may be useful for anaesthesia in animals where kinetics are unknown; in disease states; and where intercurrent therapies affect propofol disposition.

Evaluation of a new analyser for rapid measurement of blood propofol concentration during cardiac surgery

We report laboratory and clinical evaluations of a blood propofol concentration analyser. Laboratory experiments used volunteer blood spiked with known propofol concentrations over the clinically relevant concentrations from 0.5 to 16 μg.ml(-1) to assess linearity and the influence of haematocrit and concurrent drug administration. Analyser concentrations demonstrated excellent linearity (R(2) = 0.999). Blood spiked with commonly used drugs showed no significant variation compared to unspiked controls. Propofol measurements were largely independent of haemoglobin concentration. A 6% decay in propofol concentration was observed at the highest prepared concentration. Clinical performance of the analyser was assessed using 80 arterial blood samples from 72 patients receiving propofol infusions during cardiac surgery. Samples were processed using the propofol analyser, and high performance liquid chromatography (HPLC) used as a gold-standard comparator. These data demonstrated excellent agreement between the propofol analyser and HPLC with a bias of 0.13 μg.ml(-1) and precision of -0.16 to 0.42 μg.ml(-1).

661 Driving Ability Is Normal Within One Hour of Routine Colonoscopy Using Propofol Sedation

It is commonly recommended that patients should refrain from driving for 24 hours after endoscopy in which sedation is given. In Japan, routinely, driving is prohibited after receiving sedation. Whether patients can safely drive (e.g., home or to work) 1 hour after routine colonoscopy using propofol sedation is unknown. The aim of this study was to assess psychomotor activity, driving skills, and the blood propofol level before and 1 hour after colonoscopy using propofol sedation.