In vitro investigations of jet-pulses for the measurement of respiratory impedance in newborns

Schmidt, M.; Foitzik, B.; Hochmuth, Olaf; Schmalisch, Gerd

doi:10.1183/09031936.99.14511569

Cited by 5 publications

(3 citation statements)

References 20 publications

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“…The respiratory inertance was measured by brief flow pulses as described previously (Schmidt et al 1999). Briefly, a miniaturized pneumotachograph (PNT) with integrated pressure transducers (PaedXS, Jaeger, Würzburg, Germany) (R PNT = 0.6 kPa l −1 s at 5 l min −1 , deadspace 1.5 ml) was inserted between T-piece and ETT to measure the air flow V (t) and mouth pressure P (t).…”

Section: Inertance Measurement By Fotmentioning

confidence: 99%

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Inertance measurements by jet pulses in ventilated small lungs after perfluorochemical liquid (PFC) applications

et al. 2005

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Perfluorochemical liquid (PFC) liquids or aerosols are used for assisted ventilation, drug delivery, lung cancer hyperthermia and pulmonary imaging. The aim of this study was to investigate the effect of PFC liquid on the inertance (I) of the respiratory system in newborn piglets using partial liquid ventilation (PLV) with different volumes of liquid. End-inspiratory (I(in)) and end-expiratory (I(ex)) inertance were measured in 15 ventilated newborn piglets (age < 12 h, mean weight 724 +/- 93 g) by brief flow pulses before and 80 min after PLV using a PFC volume (PF5080, 3 M) of 10 ml kg(-1) (N = 5) or 30 ml kg(-1) (N = 10). I was calculated from the imaginary part of the measured respiratory input impedance by regression analysis. Straight tubes with 2-4 mm inner diameter were used to validate the equipment in vitro by comparison with the analytically calculated values. In vitro measurements showed that the measuring error of I was <5% and that the reproducibility was better than 1.5%. The correlation coefficient of the regression model to determine I was >0.988 in all piglets. During gas ventilation, I(in) and I(ex) (mean +/- SD) were 31.7 +/- 0.8 Pa l(-1) s(2) and 33.3 +/- 2.1 Pa l(-1) s(2) in the 10 ml group and 32.4 +/- 0.8 Pa l(-1) s(2) and 34.0 +/- 2.5 Pa l(-1) s(2) in the 30 ml group. However, I of the 3 mm endotracheal tube (ETT) used was already 26.4 Pa l(-1) s(2) (about 80% of measured I). During PLV, there was a minimal increase of I(in) to 33.1 +/- 2.5 Pa l(-1) s(2) in the 10 ml group and to 34.5 +/- 2.7 Pa l(-1) s(2) in the 30 ml group. In contrast, the increase of I(ex) was dramatically larger (p < 0.001) to 67.7 +/- 13.3 Pa l(-1) s(2) and to 74.8 +/- 9.3 Pa l(-1) s(2) in the 10 ml and 30 ml groups, respectively. Measurements of I by jet pulses in intubated small animals are reproducible. PFC increases the respiratory inertance, but the magnitude depends considerably on its spatial distribution which changes during the breathing cycle. Large differences between I(in) and I(ex) are an indicator for liquid in airways or the ETT.

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Section: Inertance Measurement By Fotmentioning

confidence: 99%

“…The FOT by brief flow pulses was initially developed for measuring respiratory mechanics without imposing an increased dead space in small lungs (Schmidt et al 1999). In this study, all measurements could be performed during ongoing and uninterrupted mechanical ventilation.…”

Section: Inertance Measurements By Fotmentioning

confidence: 99%

Inertance measurements by jet pulses in ventilated small lungs after perfluorochemical liquid (PFC) applications

et al. 2005

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“…In addition, the FTT has the advantage that the inspired oxygen fraction can be adjusted, tracer gases for other RFTs can be added [13], and it can easily be used in infants requiring continuous positive airway pressure [22]. Furthermore, the FTT can be combined with oesophageal manometry [23] or forced oscillations to investigate lung mechanics during tidal breathing [24]. The FTT also allows continuous assessment of air leaks between the face and the mask which is helpful for maintaining airtight placement of the face mask [19].…”

Section: Relative Advantages and Limitations Of The Two Methodsmentioning

confidence: 99%

Effect of apparatus dead space on breathing parameters in newborns: “flow-through”versusconventional techniques

et al. 2001

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Commercial devices for tidal breathing measurements in newborns allow only short-term measurements, due to the high apparatus dead space of the face mask and pneumotachometer. The¯ow-through technique (FTT) minimizes the dead space by a background¯ow, thereby allowing long-term measurements. The aim of this study was to investigate the comparability of tidal breathing parameters using both techniques.Paired measurements of tidal breathing were performed in 86 sleeping infants (median (range) body weight 2.8 kg (1.9±5.3 kg), age 65 days (3±150 days)), using the FTT and SensorMedics 2600 (SM 2600).There was a signi®cant bias (pv0.001) in all tidal breathing parameters. Compared with the FTT, increases (95% con®dence interval (CI)) in tidal volume (VT), respiratory frequency (fR), and minute ventilation (V'E) were 0.74 (0.5±1.0) mL . kg -1 , 9.0 (6.9±11.2) . min -1 and 92 (74±109) mL . min -1 . kg -1 when measured with the SM 2600, representing average increases of 13, 17 and 30%, respectively, in response to the added dead space. By contrast, time to peak tidal expiratory¯ow as a proportion of expiratory time (tPTEF/tE) was changed by -0.09 (-0.11±-0.08). The mean (95% CI) change in tPTEF/tE of -54 (-62±-45)%, when measured in infants by the SM 2600, was remarkably similar to that observed during in vitro validation studies (-59 (-73±-44)%), suggesting that the discrepancies in timing parameters may be largely attributable to differences in signal processing.In conclusion, differences in measurement technique and precision of the devices used can result in signi®cant differences in tidal breathing parameters. This may impede the comparison of results within and between infants and the clinical interpretation of tidal breathing measurements in newborns. Eur Respir J 2001; 17: 108±114.

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A Distributed Telemedical System for Monitoring of the Respiratory Mechanics by Enhanced Interrupter Technique

Jablonski

Mroczka

2010

Wearable and Autonomous Biomedical Devices and Systems for Smart Environment

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In vitro investigations of jet-pulses for the measurement of respiratory impedance in newborns

Cited by 5 publications

References 20 publications

Inertance measurements by jet pulses in ventilated small lungs after perfluorochemical liquid (PFC) applications

Inertance measurements by jet pulses in ventilated small lungs after perfluorochemical liquid (PFC) applications

Effect of apparatus dead space on breathing parameters in newborns: “flow-through”versusconventional techniques

A Distributed Telemedical System for Monitoring of the Respiratory Mechanics by Enhanced Interrupter Technique

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