Adherence of volatile propofol to various types of plastic tubing

Maurer, Felix; Lorenz, D; Pielsticker, G.; Volk, Th.; Sessler, Daniel I.; Baumbach, Jan; Kreuer, Sascha

doi:10.1088/1752-7163/aa567e

Cited by 12 publications

(15 citation statements)

References 21 publications

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“…Analytical validation of the EDMON device confirmed a wide linear range, high precision, good resolution, and low limits of detection and quantification which are consistent with the manufacturer’s specifications [ 35 ]. We excluded strong carry-over effects with the recommended measurement setup, confirming that the inert tubing material perfluoroalkoxy alkane and polytetrafluoroethylene is unlikely to bind propofol as previously reported [ 36 ]. Additionally, propofol is highly hydrophobic with a solubility of only 124mg/L [ 37 ], and is therefore unlikely to accumulate in condensate building up in the tubing at any humidity level.…”

Section: Discussionsupporting

confidence: 79%

Humidity and measurement of volatile propofol using MCC-IMS (EDMON)

Teucke

Maurer

Müller-Wirtz

et al. 2022

J Clin Monit Comput

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The bedside Exhaled Drug MONitor – EDMON measures exhaled propofol in ppbv every minute based on multi-capillary column – ion mobility spectrometry (MCC-IMS). The MCC pre-separates gas samples, thereby reducing the influence of the high humidity in human breath. However, preliminary analyses identified substantial measurement deviations between dry and humid calibration standards. We therefore performed an analytical validation of the EDMON to evaluate the influence of humidity on measurement performance. A calibration gas generator was used to generate gaseous propofol standards measured by an EDMON device to assess linearity, precision, carry-over, resolution, and the influence of different levels of humidity at 100% and 1.7% (without additional) relative humidity (reference temperature: 37°C). EDMON measurements were roughly half the actual concentration without additional humidity and roughly halved again at 100% relative humidity. Standard concentrations and EDMON values correlated linearly at 100% relative humidity (R²=0.97). The measured values were stable over 100min with a variance ≤ 10% in over 96% of the measurements. Carry-over effects were low with 5% at 100% relative humidity after 5min of equilibration. EDMON measurement resolution at 100% relative humidity was 0.4 and 0.6 ppbv for standard concentrations of 3 ppbv and 41 ppbv. The influence of humidity on measurement performance was best described by a second-order polynomial function (R²≥0.99) with influence reaching a maximum at about 70% relative humidity. We conclude that EDMON measurements are strongly influenced by humidity and should therefore be corrected for sample humidity to obtain accurate estimates of exhaled propofol concentrations.

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Section: Discussionsupporting

confidence: 79%

Humidity and measurement of volatile propofol using MCC-IMS (EDMON)

Teucke

Maurer

Müller-Wirtz

et al. 2022

J Clin Monit Comput

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“…A reason for the effect could be the adhesion of propofol to the inner surfaces of the HovaCAL and the MCC/IMS. Interactions of gaseous propofol with plastic surfaces have been investigated [19]. Plastic in form of polytetrafluorethylene (PTFE) tubing is installed in the MCC/IMS as gas-conveying line.…”

Section: Discussionmentioning

confidence: 99%

Calibration and validation of a MCC/IMS prototype for exhaled propofol online measurement

Maurer

Walter

Geiger

et al. 2017

Journal of Pharmaceutical and Biomedical Analysis

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Propofol is a commonly used intravenous general anesthetic. Multi-capillary column (MCC) coupled Ion-mobility spectrometry (IMS) can be used to quantify exhaled propofol, and thus estimate plasma drug concentration. Here, we present results of the calibration and analytical validation of a MCC/IMS pre-market prototype for propofol quantification in exhaled air. Calibration with a reference gas generator yielded an R≥0.99 with a linear array for the calibration curve from 0 to 20 ppb. The limit of quantification was 0.3 ppb and the limit of detection was 0.1 ppb. The device is able to distinguish concentration differences >0.5 ppb for the concentration range between 2 and 4 ppb and >0.9 ppb for the range between 28 and 30 ppb. The imprecision at 20 ppb is 11.3% whereas it is 3.5% at a concentration of 40 ppb. The carry-over duration is 3min. The MCC/IMS we tested provided online quantification of gaseous propofol over the clinically relevant range at measurement frequencies of one measurement each minute.

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“…Polyurethane or tubing made of silicone may absorb most of the propofol molecules and are thus unsuitable. 32 Few authors describe either the types of materials in the sampling tubes or the airway devices used. We set up the breathing circuit with previously tested materials only, as directed by the manufacturer.…”

Section: Discussionmentioning

confidence: 99%

Online exhaled propofol monitoring in normal‐weight and obese surgical patients

Braathen

Rimstad

Dybvik

et al. 2022

Acta Anaesthesiol Scand

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Background: Ion mobility spectrometry (IMS) allows for online quantification of exhaled propofol concentrations. We aimed to validate a bedside online IMS device, the Edmon ® , for predicting plasma concentrations of propofol in normal-weight and obese patients. Methods:Patients with body mass index (BMI) >20 kg/m 2 scheduled for laparoscopic cholecystectomy or bariatric surgery were recruited. Exhaled propofol concentrations (C A ), arterial plasma propofol concentrations (C P ) and bispectral index (BIS) values were collected during target-controlled infusion (TCI) anaesthesia. Generalised estimation equation (GEE) was applied to all samples and stable-phase samples at different delays for best fit between C P and C A . BMI was evaluated as covariate. BIS and exhaled propofol correlations were also assessed with GEE.Results: A total of 29 patients (BMI 20.3-53.7) were included. A maximal R 2 of 0.58 was found during stable concentrations with 5 min delay of C A to C P ; the intercept a = −0.69 (95% CI −1.7, 0.3) and slope b = 0.87 (95% CI 0.7, 1.1). BMI was found to be a non-significant covariate. The median absolute performance error predicting plasma propofol concentrations was 13.4%. At a C A of 5 ppb, the model predicts a C P of 3.6 μg/ml (95% CI ±1.4). There was a maximal negative correlation of R 2 = 0.44 at 2-min delay from C A to BIS. Conclusions: Online monitoring of exhaled propofol concentrations is clinically feasible in normal-weight and obese patients. With a 5-min delay, our model outperforms the Marsh plasma TCI model in a post hoc analysis. Modest correlation with plasma concentrations makes the clinical usefulness questionable. Editorial CommentMeasurement of exhaled propofol concentration and correlation to drug pharmacodynamics for patients in different weight categories is needed to see if the tool has general clinical value. This trial provides further experience with this method.

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Adherence of volatile propofol to various types of plastic tubing

Cited by 12 publications

References 21 publications

Humidity and measurement of volatile propofol using MCC-IMS (EDMON)

Humidity and measurement of volatile propofol using MCC-IMS (EDMON)

Calibration and validation of a MCC/IMS prototype for exhaled propofol online measurement

Online exhaled propofol monitoring in normal‐weight and obese surgical patients

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