Resistance and inertia of endotracheal tubes used in infants during periodic flow

Jj, Pérez Fontán; Gp, Heldt; Ga, Gregory

doi:10.1097/00003246-198512000-00014

Cited by 11 publications

(3 citation statements)

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“…However, in newborns and small animals, the respiratory rates are much higher and the diameters of airways and endotracheal tubes (ETT) are considerably smaller than in adults. Several studies have already shown that under these conditions, inertive forces contributed significantly to the respiratory mechanics (Davis andLands 1997, Lanteri et al 1999) and to the pressure drop across the ETT (Perez Fontan et al 1985, Guttmann et al 2000. Furthermore, up to now it is not well known how any liquid instillation in the lungs will affect the respiratory inertance.…”

Section: Introductionmentioning

confidence: 99%

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: Introductionmentioning

confidence: 99%

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

et al. 2005

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“…[22][23][24] In the patient with mechanical ventilation, R aw can be directly measured through plethysmography or indirectly estimated using PIP, plateau pressure, and flow by mechanical ventilation. 12,25 In our study, R aw was most affected by the decreased ventilation area of the ETT resulting from insertion of the SC, and high R aw contributed to the relatively high PIP in VC-CMV. In addition, higher flow rates of ventilation and steady-state suctioning of the SC in the distal ETT aggravated the PIP level.…”

Section: Comparison With Past Study Findingsmentioning

confidence: 56%

Optimizing effects on airway pressure and minute volume during closed endotracheal suctioning: a simulated lung model

et al. 2021

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A closed suction system is used to remove endotracheal secretions without interrupting the patient’s ventilation. Closed suctioning may reduce adverse effects associated with suctioning with, for example, decreased clinical signs of hypoxemia and limited environmental, personnel, and patient contamination. However, it is not clear whether ventilation is maintained during the procedure. We aimed to determine the effects of endotracheal tube (ETT) size, suction catheter (SC) size, and SC length in the ETT on ventilation parameters measured during suction. Suction was performed on a test lung, ventilated with either volume-controlled continuous mandatory ventilation (VC-CMV) or pressure-controlled continuous mandatory ventilation (PC-CMV) using ETT sizes of 6.0–8.5 mm paired with SC sizes of 8–16 French gauge (Fr = 0.33 mm). Airway resistance ( Raw), peak inspiratory pressure (PIP), positive end-expiratory pressure (PEEP), and expiratory minute volume ( Vexp) were recorded for each ventilation episode by a HAMILTON-G5 ventilator. Here, Raw was considerably increased by insertion of the SC into the ETT. This Raw effect altered the PIP and Vexp. PIP was increased in VC-CMV because the ventilation area of the ETT was reduced, and Vexp was decreased in PC-CMV in relation to the size of the SC. PEEP decreased with application of the 16 Fr SC and 30 L/min flow rate in VC-CMV. We conclude that airway pressure and minute volume are not maintained during closed endotracheal suctioning with VC-CMV and PC-CMV, respectively. The degree of interference to ventilation is affected through selection of appropriate SC size and ventilation settings.

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“…The contribution of inertial forces is relatively small and can be neglected (8). Therefore, equation 1 can be closely approximated by:…”

Section: Methodsmentioning

confidence: 99%

Mechanics of the Respiratory System during Passive Exhalation in Preterm Lambs

1989

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ABSTRACT. Previous studies have shown large inhomogeneities in the distributions of ventilation and perfusion of newborn infants with hyaline membrane disease. The purpose of this study was to show that measurements of lung mechanics also show evidence of lung inhomogeneities and that a multiple compartment analysis of mechanics gives a more accurate representation of passive exhalation flow and volume than single valued mechanics. We studied 10 sedated preterm lambs (130 d gestation) weighing 2.2 f 0.3 kg at 4 h postnatal age. Passive exhalation lung mechanics of the respiratory system were measured by obstructing gas flow near end inhalation then, after pressures within the lung reached equilibrium, allowing the animals to exhale to the atmosphere. Airway pressure and flow signals were monitored by a computer then analyzed using single and multiple compartment analyses. Single compartment analysis of time constant (7) in s, respiratory system resistance (R) in cm H20/L/s and quasistatic compliance (C) in mL/cm H 2 0 yielded 7 = 0.16 f 0.07, R = 92 f 17, and C = 1.8 f 1.1 (mean f SD). Multiple compartment analysis yielded "fast compartment" 7, = 0.10 f 0.04, R1 = 90 + 28, and C1 = 1.1 f 0.5 and "slow compartment" 7 2 = 0.25 f 0.12, R2 = 503 + 288, and C2 = 0.7 + 0.6. All of the animals studied exhibited nonlinearity in their flow-volume plots. Calculated flow-volume plots were much more accurately portrayed by the twocompartment analysis than by single valued mechanics. Multiple compartment analysis of lung mechanics may provide useful insight into the pathophysiology of the preterm lab with hyaline membrane disease. (Pediafr Res 26: 425-428,1989) Abbreviations C, quasistatic compliance of the respiratory system WT, fraction of tidal volume ventilating each lung compartment HMD, hyaline membrane disease R, respiratory system resistance 7, passive exhalation time constant V, volume of gas in the lungs above functional residual capacity subscript 1 and 2 refer to the "fast" and "slow" compartments, respectively. PIP, peak inspiratory pressure PEEP, positive end expiratory pressure Several studies on infants with HMD suggest that gross inhomogeneities exist in their distributions of ventilation and perfusion. The elevations of nitrogen (1, 2), oxygen (1-3), and carbon dioxide (4, 5) gradients between alveolar gas and arterial blood suggest that ventilation-perfusion mismatching exists and that there are respiratory units with both lower and higher than normal ventilation-perfusion ratios. Additional studies using nitrogen washout suggest that these infants also have an uneven distribution of ventilation (6). Multiple compartment analyses of the results from these studies provide valuable information that influences the interpretations of the pulmonary pathophysiology of infants with HMD.After considering the strong evidence of lung inhomogeneities in infants with HMD, we speculated that lung mechanics measurements would also require multiple compartment analysis for accurate representation of flow and volume d...

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Resistance and inertia of endotracheal tubes used in infants during periodic flow

Cited by 11 publications

References 0 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

Optimizing effects on airway pressure and minute volume during closed endotracheal suctioning: a simulated lung model

Mechanics of the Respiratory System during Passive Exhalation in Preterm Lambs

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