Flow measurement in mechanical ventilation: a review.

Accurate monitoring of flow rate and volume exchanges is essential to minimize ventilator-induced lung injury. Mechanical ventilators employ flowmeters to estimate the amount of gases delivered to patients and use the flow signal as a feedback to adjust the desired amount of gas to be delivered. Since flowmeters play a crucial role in this field, they are required to fulfill strict criteria in terms of dynamic and static characteristics. Therefore, mechanical ventilators are equipped with only the following kinds of flowmeters: linear pneumotachographs, fixed and variable orifice meters, hot wire anemometers, and ultrasonic flowmeters. This paper provides an overview of these sensors. Their working principles are described together with their relevant advantages and disadvantages. Furthermore, the most promising emerging approaches for flowmeters design (i.e., fiber optic technology and three dimensional micro-fabrication) are briefly reviewed showing their potential for this application.

[1]  A. Smits,et al.  Temperature corrections for constant temperature and constant current hot-wire anemometers , 2010 .

[2]  H. H. Bruun.  Hot-wire anemometry , 1995 .

[3]  Emiliano Schena,et al.  Optical Fiber-Based MR-Compatible Sensors for Medical Applications: An Overview , 2013, Sensors.

[4]  C. Bellido,et al.  Design and calibration of unicapillary pneumotachographs. , 1998, Journal of applied physiology.

[5]  Sergio Silvestri,et al.  A transistor based air flow transducer for thermohygrometric control of neonatal ventilatory applications. , 2008, The Review of scientific instruments.

[6]  I. Yoshiya,et al.  A bidirectional respiratory flowmeter using the hot-wire principle. , 1975, Journal of applied physiology.

[7]  Christian Buess.  Transit-time ultrasonic airflow meter for medical application , 1988 .

[8]  Richard Plavka,et al.  Expired tidal volumes measured by hot‐wire anemometer during high‐frequency oscillation in preterm infants , 2006, Pediatric pulmonology.

[9]  Sergio Silvestri,et al.  Linearity dependence on oxygen fraction and gas temperature of a novel Fleisch pneumotachograph for neonatal ventilation at low flow rates , 2012 .

[10]  Sergio Silvestri,et al.  A high sensitivity fiber optic macro-bend based gas flow rate transducer for low flow rates: theory, working principle, and static calibration. , 2013, The Review of scientific instruments.

[11]  T. P. Leung,et al.  Performance of conical entrance orifice plates at low Reynolds numbers , 1985 .

[12]  Peter Freymuth,et al.  Frequency response and electronic testing for constant-temperature hot-wire anemometers , 1977 .

[13]  Göran Stemme,et al.  A static turbine flow meter with a micromachined silicon torque sensor , 2003 .

[14]  A. Micco.  A sensitive flow direction sensor. , 1973, Journal of applied physiology.

[15]  HighWire Press.  Proceedings of the Royal Society of London. Series A, Containing papers of a mathematical and physical character , 1934 .

[16]  Sergio Silvestri,et al.  An optical fiber based flow transducer for infant ventilation: Measurement principle and calibration , 2011, 2011 IEEE International Symposium on Medical Measurements and Applications.

[17]  John G. Webster,et al.  Ultrasonic Measurement of Respiratory Flow , 1980, IEEE Transactions on Biomedical Engineering.

[18]  David W. Kaczka,et al.  Four methods of measuring tidal volume during high-frequency oscillatory ventilation , 2006, Critical care medicine.

[19]  A. Rothberg,et al.  Calibration of Fleisch and screen pneumotachographs for use with various oxygen concentrations , 1990, Medical and Biological Engineering and Computing.

[20]  R. Branson,et al.  Humidification in the intensive care unit. Prospective study of a new protocol utilizing heated humidification and a hygroscopic condenser humidifier. , 1993, Chest.

[21]  A. Fleisch.  Der Pneumotachograph; ein Apparat zur Geschwindigkeitsregistrierung der Atemluft , 1925, Pflüger's Archiv für die gesamte Physiologie des Menschen und der Tiere.

[22]  Peter D. Sly,et al.  Measurement of flow and volume , 1996 .

[23]  H. H. Bruun,et al.  Hot-Wire Anemometry: Principles and Signal Analysis , 1996 .

[24]  R. W. Miller,et al.  Flow Measurement engineering handbook (second edition) , 1989 .

[25]  Mitsuhiro Shikida,et al.  A catheter-type flow sensor for measurement of aspirated- and inspired-air characteristics in the bronchial region , 2009 .

[26]  F. Nieuwstadt,et al.  The calibration of (multi-)hot-wire probes. 2. Velocity-calibration , 2004 .

[27]  Qingping Yang,et al.  DP flow sensor using optical fibre Bragg grating , 2001 .

[28]  S. Silvestri,et al.  Influence of gas temperature on the performances of a low dead space capillary type pneumotachograph for neonatal ventilation , 2009, 2009 Annual International Conference of the IEEE Engineering in Medicine and Biology Society.

[29]  R. N. Karekar,et al.  Optical fiber‐based macrobend free air flow sensor using a hinge joint: A preliminary report , 2008 .

[30]  S. Z. Turney,et al.  A coaxial ultrasonic pneumotachometer , 2006, Medical and biological engineering.

[31]  L Battista,et al.  An air flow sensor for neonatal mechanical ventilation applications based on a novel fiber-optic sensing technique. , 2013, The Review of scientific instruments.

[32]  Janet Stocks,et al.  Infant respiratory function testing , 1996 .

[33]  J. P. Zock.  Linearity and frequency response of fleisch type pneumotachometers , 1981, Pflügers Archiv.

[34]  Huibert Burger,et al.  Correction factors for oxygen and flow-rate effects on neonatal Fleisch and Lilly pneumotachometers , 2003, Pediatric critical care medicine : a journal of the Society of Critical Care Medicine and the World Federation of Pediatric Intensive and Critical Care Societies.

[35]  M. Davies,et al.  The effect of perfluorocarbon vapour on the measurement of respiratory tidal volume during partial liquid ventilation , 2000, Physiological measurement.

[36]  J E Cotes,et al.  Lung volumes and forced ventilatory flows , 1993, European Respiratory Journal.

[37]  Jan F. Kreider,et al.  Handbook of Heating, Ventilation, and Air Conditioning , 2000 .

[38]  Mitsuhiro Shikida,et al.  Catheter flow sensor with temperature compensation for tracheal intubation tube system , 2014 .

[39]  S. Turney,et al.  A mathematical model for the ultrasonic measurement of respiratory flow , 2006, Medical and biological engineering.

[40]  Xu Guang Huang,et al.  A Simple Fiber-Optic Flowmeter Based on Bending Loss , 2009, IEEE Sensors Journal.

[41]  Kenneth T. V. Grattan,et al.  Fiber optic sensor technology: an overview , 2000 .

[42]  Fritz Rohrer,et al.  Der Strömungswiderstand in den menschlichen Atemwegen und der Einfluss der unregelmässigen Verzweigung des Bronchialsystems auf den Atmungsverlauf in verschiedenen Lungenbezirken , 1915, Pflüger's Archiv für die gesamte Physiologie des Menschen und der Tiere.

[43]  A.F.P. van Putten,et al.  A silicon bidirectional flow sensor for measuring respiratory flow , 1997, IEEE Transactions on Biomedical Engineering.

[44]  P D Sly,et al.  In vitro assessment of an ultrasonic flowmeter for use in ventilated infants. , 2000, The European respiratory journal.

[45]  S V Dawson,et al.  Linearity and frequency response of pneumotachographs. , 1972, Journal of applied physiology.

[46]  A. Coates,et al.  A very low dead space pneumotachograph for ventilatory measurements in newborns. , 1990, Journal of applied physiology.

[47]  R. Zhu,et al.  Low-cost portable respiration monitor based on micro hot-film flow sensor , 2010, 2010 IEEE International Conference on Nano/Molecular Medicine and Engineering.

[48]  R. W. Miller,et al.  Flow Measurement Engineering Handbook , 1983 .

[49]  D. Baldwin,et al.  Optimized temperature and deadspace correction improve analysis of multiple breath washout measurements by ultrasonic flowmeter in infants , 2007, Pediatric pulmonology.

[50]  M. Heulitt,et al.  Accuracy of small tidal volume measurement comparing two ventilator airway sensors , 2013, Journal of Pediatric Intensive Care.

[51]  A Cantilever Force Sensor Combined With a Spherical Reflecting Mirror for Sensitivity Enhancement of an Optical Detection System , 2009, IEEE Journal of Selected Topics in Quantum Electronics.

[52]  A. Rothberg,et al.  Effects of temperature and composition on the viscosity of respiratory gases. , 1989, Journal of applied physiology.

[53]  Andrea Scorza,et al.  Preliminary evaluation of a fiber-optic sensor for flow measurements in pulmonary ventilators , 2011, 2011 IEEE International Symposium on Medical Measurements and Applications.

[54]  H. C. Hardy,et al.  The Velocity of Sound in Air , 1942 .

[55]  J E Cotes,et al.  [Lung volumes and forced ventilatory flows. Work Group on Standardization of Respiratory Function Tests. European Community for Coal and Steel. Official position of the European Respiratory Society]. , 1994, Revue des maladies respiratoires.

[56]  Emrah Özahi,et al.  Simple methods for low speed calibration of hot-wire anemometers , 2010 .

[57]  Sergio Silvestri,et al.  An orifice meter for bidirectional air flow measurements: Influence of gas thermo-hygrometric content on static response and bidirectionality , 2013 .

[58]  J. Osborn.  A flowmeter for respiratory monitoring. , 1978, Critical care medicine.

[59]  Sergio Silvestri,et al.  Micromachined Flow Sensors in Biomedical Applications , 2012, Micromachines.

[60]  Anton F. P. van Putten,et al.  Silicon thermal anemometry : developments and applications , 1996 .

[61]  Sergio Silvestri,et al.  A novel target-type low pressure drop bidirectional optoelectronic air flow sensor for infant artificial ventilation: measurement principle and static calibration. , 2011, The Review of scientific instruments.

[62]  Air features in spirometric transducers , 2006 .

[63]  Nam-Trung Nguyen,et al.  Micromachined flow sensors—a review , 1997, Flow Measurement and Instrumentation.