Phase analysis in high-frequency oscillation

Lee, S; Blowes, R; Milner, A. David

doi:10.1016/s1350-4533(98)00042-3

Cited by 4 publications

(2 citation statements)

References 6 publications

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“…By studying the intricacy of oscillatory mechanics,6 7there are potentially ways of further improving the efficiency of this type of ventilation. Hoskyns et al suggested that the delivered volume during high frequency oscillations in a system driven by a sine wave pump is greatest at resonance frequency of the intubated respiratory system,15 while Dorkin et al found this frequency to lie between 13 and 23 Hz in premature neonates with respiratory disease 16…”

Section: Discussionmentioning

confidence: 99%

Resonance frequency in respiratory distress syndrome

Lee

Milner

2000

Archives of Disease in Childhood - Fetal and Neonatal Edition

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Aim-To observe how the resonance frequency changes with the course of respiratory distress syndrome (RDS), by examining the eVect of changing static compliance on the resonance frequency in premature infants. Methods-In 12 ventilated premature infants with RDS (mean gestational age 26.6 weeks, mean birth weight 0.84 kg), resonance frequency and static compliance were determined serially using phase analysis and single breath mechanics technique respectively in the first seven days of life. Results-The minimum number of measurements done in any one baby was three and maximum was five in this seven day study period. The first measurement in each baby was done within the first 72 hours of life. The increase in compliance in this period varied from 27% to 179%. The variation in the corresponding resonance frequency was within 2 Hz in eight babies and within 6 Hz in all recruited babies. Conclusions-The resonance frequency of the respiratory system in preterm infants with RDS remains remarkably constant in the early stages of the illness, despite relatively large changes in static compliance. (Arch Dis Child Fetal Neonatal Ed 2000;83:F203-F206)

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Section: Discussionmentioning

confidence: 99%

Resonance frequency in respiratory distress syndrome

Lee

Milner

2000

Archives of Disease in Childhood - Fetal and Neonatal Edition

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“…13,14 The FOT principles are also used in the research of new optimization methods for more efficient high-frequency ventilation in neonatal practice. 19 …”

Section: Medical Research Applications Under Developmentmentioning

confidence: 99%

New impedance spectrometer for scientific and clinical studies of the respiratory system

Melo

Werneck

Giannella-Neto

2000

Review of Scientific Instruments

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The simple techniques generally used to investigate the biomechanical properties associated with the respiratory process are able to identify only basic characteristics, just supplying an initial representation of the complex behavior of the respiratory system. A much more detailed description can be obtained by the forced oscillation technique (FOT). Requiring very little cooperation of the subject, this technique allows a noninvasive evaluation of the mechanical impedance of the respiratory system. Although the FOT has a great scientific and clinical potential, this is attended by technical difficulties and has yet to be put to widespread use. In this context, this work describes a new flexible, open architecture, virtual-instrument-based impedance spectrometer for the FOT. After the design details are described, the system accuracy is evaluated investigating mechanical models simulating normal and individuals with restrictive disease. This analysis revealed errors smaller than 4% in modulus and 7° in phase. Experimental results obtained in a normal and an asthmatic subject, presented as examples, revealed mean resistance in asthmatic (5.72 cm H2O/l/s) higher than in normal (2.47 cm H2O/l/s). The mean-reactance curve revealed higher resonance frequency in the asthmatic subject (∼29 Hz) than in the normal one (∼9 Hz). A higher influence of the upper airways impedance of the asthmatic individual was also observed. These results are in close agreement with physiological fundamentals, supplying substantial evidence that this instrument can contribute to the production of more detailed biophysical respiratory descriptions and composes an improved basis for the fast and easy implementation of complex medical research projects.

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Determination of resonance frequency of the respiratory system in respiratory distress syndrome

Lee

Alexander

Blowes

et al. 1999

Archives of Disease in Childhood - Fetal and Neonatal Edition

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Aim-To measure tidal volume delivery produced by high frequency oscillation (HFO) at a range of frequencies including the resonance frequency. Methods-Eighteen infants with respiratory distress syndrome were recruited (median gestation 28.7 weeks). Each was ventilated at frequencies between 8 and 30 Hertz. Phase analysis was performed at various points of the respiratory cycle. HFO was provided by a variable speed piston device. Resonance frequency was determined from the phase relation between the cyclical movements of the piston and pressure changes at the airway opening. Tidal volume was measured using a jacket plethysmograph. Results-The results were most reproducible when analysis was performed at the end of inspiration (within 1 Hz in nine out of 10 cases). Comparison between tidal volume delivery at 10 Hz and resonance frequency was made in 10 subjects. Delivery was significantly higher at resonance than at 10 Hertz (mean percentage increase 92%, range 9-222%). Conclusions-These preliminary findings suggest that there is improved volume delivery at resonance frequency. (Arch Dis Child Fetal Neonatal Ed 1999;80:F198-F202)

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Phase analysis in high-frequency oscillation

Cited by 4 publications

References 6 publications

Resonance frequency in respiratory distress syndrome

Resonance frequency in respiratory distress syndrome

New impedance spectrometer for scientific and clinical studies of the respiratory system

Determination of resonance frequency of the respiratory system in respiratory distress syndrome

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