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• 1.
Mälardalen University, School of Innovation, Design and Engineering.
Mälardalen University, School of Innovation, Design and Engineering. Mälardalen University, School of Innovation, Design and Engineering. Mälardalen University, School of Innovation, Design and Engineering. Mälardalen University, School of Innovation, Design and Engineering. Mälardalen University, School of Innovation, Design and Engineering. Mälardalen University, School of Innovation, Design and Engineering. Mälardalen University, School of Innovation, Design and Engineering.
A technique based on laser Doppler flowmetry and photoplethysmography for simultaneously monitoring blood flow at different tissue depths2010In: Medical and Biological Engineering and Computing, ISSN 0140-0118, E-ISSN 1741-0444, Vol. 48, no 5, p. 415-422Article in journal (Refereed)

The aim of this study was to validate a non-invasive optical probe for simultaneous blood flow measurement at different vascular depths combining three photoplethysmography (PPG) channels and laser Doppler flowmeter (LDF). Wavelengths of the PPG were near-infrared 810 nm with source-to-detector separation of 10 and 25 mm, and green 560 nm with source-to-detector separation of 4 mm. The probe is intended for clinical studies of pressure ulcer aetiology. The probe was placed over the trapezius muscle, and depths from the skin to the trapezius muscle were measured using ultrasound and varied between 3.8 and 23 mm in the 11 subjects included. A provocation procedure inducing a local enhancement of blood flow in the trapezius muscle was used. Blood flows at rest and post-exercise were compared. It can be concluded that this probe is useful as a tool for discriminating between blood flows at different vascular tissue depths. The vascular depths reached for the different channels in this study were at least 23 mm for the near-infrared PPG channel (source-to-detector separation 25 mm), 10-15 mm for the near-infrared PPG channel (separation 10 mm), and shallower than 4 mm for both the green PPG channel (separation 4 mm) and LDF.

• 2.
Mälardalen University, School of Innovation, Design and Engineering.
Mälardalen University, School of Innovation, Design and Engineering. Mälardalen University, School of Innovation, Design and Engineering. Mälardalen University, School of Innovation, Design and Engineering. Mälardalen University, School of Innovation, Design and Engineering. Mälardalen University, School of Innovation, Design and Engineering. Mälardalen University, School of Innovation, Design and Engineering. Mälardalen University, School of Innovation, Design and Engineering.
Simultan registrering av blodflode pa flera djup2009In: Medicinteknikdagarna, Vasteras, 2009Conference paper (Refereed)
• 3.
Hok Instrument AB.
Autoliv Dev AB. Mälardalen University, School of Innovation, Design and Engineering. Imego. Hok Instrument AB.
Breath Analyzer for Alcolocks and Screening Devices2010In: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748, Vol. 10, no 1, p. 10-15Article in journal (Refereed)

Alcolocks and alcohol screening devices are becoming commonplace, and their use is expected to grow rapidly with cost reduction and improved usability. A new breath analyzer prototype is demonstrated, with the prospects of eliminating the mouthpiece, reducing expiration time and volume, improving long-term stability, and reducing life cycle cost. Simultaneous CO measurements compensate for the sample dilution and unsaturated expiration. Infrared transmission spectroscopy is used for both the alcohol and CO measurement, yet the entire system is contained within a small handheld unit. Experimental results are reported on the device sensitivity, linearity, resolution, and influence from varying measuring distance. The correlation between early and full-time sampling was established in 60 subjects. Basic concept verification was obtained, whereas resolution and selectivity still needs to be improved. Further improvements are expected by system optimization and integration.

• 4.
Mälardalen University, School of Innovation, Design and Engineering.
Improved breath alcohol analysis with use of carbon dioxide as the tracer gas2010Doctoral thesis, comprehensive summary (Other academic)

State-of-the-art breath analysers require a prolonged expiration into a mouthpiece to obtain the accuracy required for evidential testing and screening of the alcohol concentration. This requirement is unsuitable for breath analysers used as alcolock owing to their frequent use and the fact that the majority of users are sober drivers; as well as for breath testing in uncooperative persons.

This thesis presents a method by which breath alcohol analysis can be improved, using carbon dioxide (CO2) as the tracer gas, offering quality control of the breath sample, enabling the mouthpiece to be eliminated, and bringing about a significant reduction in the time and effort required for a breath alcohol screening test. With simultaneous measurement of the ethanol and the CO2 concentrations in the expired breath, the end-expiratory breath alcohol concentration (BrAC) can be estimated from an early measurement, without risk of underestimation.

Comparison of CO2 and water (H2O) as possible tracer gases has shown that the larger intra- and inter-individual variations in the (end-expiratory) concentration is a drawback for CO2 whereas the advantages are a low risk of underestimation of the BrAC, and the limited influence from ambient conditions on the measured CO2 concentration. The latter is considered to be of importance because the applications likely imply that the breath tests will be conducted in an uncontrolled environment, e.g., in a vehicle or ambulance. In emergency care, the measurement of the expired CO2 concentration also provides the physicians with information about the patient's respiratory function.

My hope and belief, is that with a more simple, reliable and, user-friendly test procedure, enabled with the simultaneous measurement of the CO2 in the breath sample, the screening for breath alcohol will increase. An increased number of breath alcohol analysers installed as alcolocks and more breath alcohol tests conducted in emergency care, is likely to save lives and diminish the number and severity of injuries.

• 5.
Mälardalen University, School of Innovation, Design and Engineering.
Influence from breathing pattern on alcohol and tracer gas expirograms - implications for alcolock useManuscript (preprint) (Other academic)
• 6.
Mälardalen University, School of Innovation, Design and Engineering.
Hök Instrument AB. Mälardalen University, School of Innovation, Design and Engineering. Uppsala University.
Influence from breathing pattern on alcohol and tracer gas expirograms: Implications for alcolock use2011In: Forensic Science International, ISSN 0379-0738, E-ISSN 1872-6283, Vol. 206, no 1-3, p. 52-57Article in journal (Refereed)

Measurement of breath alcohol concentration is strongly influenced by timing and the breathing pattern. In particular, shallow expiration and hyperventilation leads to underestimation of the breath alcohol concentration. In the present study, expirograms of alcohol, water and carbon dioxide were recorded in 30 healthy individuals at various breathing manoeuvres (tidal volume, slow maximum and vital capacity expiration, breath holding, and hyperventilation). Estimation of the end expiratory alcohol concentration with the use of simultaneously measured carbon dioxide was shown to reverse the tendency of underestimation at shallow expiration and hyperventilation. These findings indicate that breath alcohol estimations can be performed at shorter expiration time and reduced expired volume compared to existing alcolocks. This is believed to improve their usability and to prevent a possible route for manipulation.

• 7.
Hök Instrument AB och Akademin för innovation, design och teknik, School of Innovation, Design and Engineering.
Mälardalen University, School of Innovation, Design and Engineering.
Improved breath alcohol analysis in patients with depressed consciousnessManuscript (preprint) (Other academic)
• 8.
Mälardalen University, School of Innovation, Design and Engineering.
Hok Instrument AB, Vasteras, Sweden. Univ Rostock, Inst Forens Med, Rostock, Germany . Univ Rostock, Dept Anaesthesiol & Intens Therapy, Rostock, Germany. Mälardalen University, School of Innovation, Design and Engineering.
Improved breath alcohol analysis in patients with depressed consciousness2010In: Medical and Biological Engineering and Computing, ISSN 0140-0118, E-ISSN 1741-0444, Vol. 48, no 11, p. 1099-1105Article in journal (Refereed)

Many patients in pre-hospital and emergency care are under the influence of alcohol. In addition, some of the more common pathological conditions can introduce a behaviour that can be mistaken to be related to alcohol inebriation. Fast quantitative determination of the breath alcohol concentration (BrAC) in emergency patients facilitates triage and medical assessment, but shallow expirations performed by non-cooperative patients reduce the measurement reliability. The aim of this study was to evaluate if breath alcohol analysis in non-cooperative patients can be improved with use of simultaneous measurement of the expired carbon dioxide (CO2). With prototypes of a handheld breath alcohol analyser based on infrared transmission spectroscopy the alcohol and CO2 concentration in expired breath from 37 cooperative and non-cooperative patients were measured. The results show that enhanced breath sampling with use of a pump and estimation of the end expiratory BrAC with use of the ratio between the measured partial pressure of CO2 ($$P_{{{\text{CO}}_{2} }}$$) and a reference value of the alveolar $$P_{{{\text{CO}}_{2} }}$$, provided adequate correlation with the blood alcohol concentration (BAC). This pre-clinical study has shown that breath alcohol analysis in shallow expirations from non-cooperative patients can be improved with use of CO2 as a tracer gas.

• 9.
Mälardalen University, School of Innovation, Design and Engineering.
Mälardalen University, School of Innovation, Design and Engineering. Mälardalen University, School of Innovation, Design and Engineering. Mälardalen University, School of Innovation, Design and Engineering.
Methodology investigation of expirograms for enabling contact free breath alcohol analysis2009In: Journal of Breath Research, ISSN 1752-7155, Vol. 3, no 3Article in journal (Refereed)

The present techniques for breath alcohol determination have usability limitations concerning practical use and the time and effort required for the test person. The rationale of the physiological assumptions in a recently demonstrated technique for breath analysis without a mouthpiece is investigated in this paper. Expirograms quantifying ethanol, carbon dioxide (CO(2)) and water (H(2)O) from 30 test subjects were analysed, with respect to the influence of individual variations in end-expiratory CO(2) and H(2)O concentrations, and possible benefits from simultaneous measurement of CO(2) or H(2)O. Both healthy subjects and patients suffering from pulmonary diseases performed breath tests with small and maximum volume expiration. The breath tests were recorded basically with a standard evidential instrument using infrared absorption spectroscopy, and equipped with a mouthpiece. Average concentrations were significantly higher for the maximum than for the small expirations. For the maximum expirations, the healthy subjects had a significantly higher end-expired PCO(2) of 4.4 +/- 0.5 kPa (mean +/- standard deviation) than the patients (3.9 +/- 0.7 kPa). The corresponding values for H(2)O were 39 +/- 1 and 38 +/- 1 mg l(-1). The results indicate that the CO(2) variability is consistent with the requirements of accuracy for alcohol ignition interlocks. In addition, CO(2) as tracer gas is preferable to H(2)O due to its low concentration in ambient air. In instruments for evidential purposes H(2)O may be required as tracer gas for increased accuracy. Furthermore, the study provides support for early determination of breath alcohol concentration, indicating that determination after 2 s will introduce an additional random error of 0.02 mg l(-1) or less.

• 10.
Mälardalen University, School of Innovation, Design and Engineering.
Hök Instrument AB. Mälardalen University, School of Innovation, Design and Engineering.
Development of a breath alcohol analyzer for use on patients in emergency care2009In: IFMBE Proceedings, vol. 25, no. 1, 2009, p. 84-87Conference paper (Refereed)

The quantification of breath alcohol concentration is considered important input in medical diagnosis and triage at emergency medical care. In many severe emergency cases, for example head injuries, stroke, heart attack, diabetes, or psychological illness, the medical condition of the patient can be mistaken for alcohol intoxication. In cases like these, quantification of the alcohol concentration would facilitate and speed up the diagnostic procedure. However, the use of breath analyzers in medical care is limited as the state-of-the-art devices require active involvement of the patient, and expiratory volume and flow incompatible with patients respiratory function. This paper presents a prototype of a handheld breath analyzer based on infrared spectroscopy which does not require active involvement from the patient and also provides direct feedback on the quality of the breath test by measurement of the expired PCO2.

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