Passive expiratory flow‐volume curve is not an accurate method to measure the respiratory time constant in rabbits

Vialet, Renaud; Monnier, André; Lagier, P.; Jammes, Yves; Tomei, Charles; Martin, Claude

doi:10.1034/j.1399-6576.1999.431008.x

Cited by 3 publications

(1 citation statement)

References 13 publications

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“…In adults, the most common reasons are increased airway or endotracheal tube resistance in combination with insufficient time for expiration ( 6 – 8 ). Adult ventilators allow for measurements of intrinsic PEEP using an end expiratory pause, after which the expiratory time constants can be obtained from the flow-volume curve ( 6 , 7 , 9 , 10 ). As far as we know, there is no equivalent technology available when providing PPV using a TPR to ventilate infants.…”

Section: Introductionmentioning

confidence: 99%

Neonatal Resuscitation With T-Piece Systems: Risk of Inadvertent PEEP Related to Mechanical Properties

et al. 2021

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Background: Resuscitation of infants using T-piece resuscitators (TPR) allow positive pressure ventilation with positive end-expiratory pressure (PEEP). The adjustable PEEP valve adds resistance to expiration and could contribute to inadvertent PEEP. The study indirectly investigated risk of inadvertent peep by determining expiratory time constants. The aim was to measure system expiratory time constants for a TPR device in a passive mechanical model with infant lung properties.Methods: We used adiabatic bottles to generate four levels of compliance (0.5–3.4 mL/cm H2O). Expiratory time constants were recorded for combinations of fresh gas flow (8, 10, 15 L/min), PEEP (5, 8, 10 cm H2O), airway resistance (50, 200 cm H2O/L/sec and none), endotracheal tube (none, size 2.5, 3.0, 3.5) with a peak inflation pressure of 15 cm H2O above PEEP.Results: Low compliances resulted in time constants below 0.17 s contrasting to higher compliances where the expiratory time constants were 0.25–0.81 s. Time constants increased with increased resistance, lower fresh gas flows, higher set PEEP levels and with an added airway resistance or endotracheal tube.Conclusions: The risk of inadvertent PEEP increases with a shorter time for expiration in combination with a higher compliance or resistance. The TPR resistance can be reduced by increasing the fresh gas flow or reducing PEEP. The expiratory time constants indicate that this may be clinically important. The risk of inadvertent PEEP would be highest in intubated term infants with highly compliant lungs. These results are useful for interpreting clinical events and recordings.

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Section: Introductionmentioning

confidence: 99%

Neonatal Resuscitation With T-Piece Systems: Risk of Inadvertent PEEP Related to Mechanical Properties

et al. 2021

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Airway response to induced muscular contraction in spontaneously breathing rabbits

Marchal

Demoulin

Leblanc

et al. 2008

Respiratory Physiology & Neurobiology

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Bronchodilation induced by muscular contraction in spontaneously breathing rabbits: Neural or mechanical?

Marchal¹,

Evrot²,

Demoulin³

et al. 2012

Respiratory Physiology & Neurobiology

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Passive expiratory flow‐volume curve is not an accurate method to measure the respiratory time constant in rabbits

Abstract: The end-inspiratory occlusion technique leads to a systemic bias in measurements of respiratory time constant, especially when the resistance of the respiratory system is elevated.

Cited by 3 publications

References 13 publications

Neonatal Resuscitation With T-Piece Systems: Risk of Inadvertent PEEP Related to Mechanical Properties

Neonatal Resuscitation With T-Piece Systems: Risk of Inadvertent PEEP Related to Mechanical Properties

Airway response to induced muscular contraction in spontaneously breathing rabbits

Bronchodilation induced by muscular contraction in spontaneously breathing rabbits: Neural or mechanical?

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