Functional residual capacity and lung mechanics at different levels of mechanical ventilation

Dw, Cartwright; Mm, Willis; Ga, Gregory

doi:10.1097/00003246-198405000-00002

Cited by 16 publications

(7 citation statements)

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“…However, a frequency of Ͻ60 breaths/min is usually used in clinical practice. 28 The reasons for not operating conventional ventilators at higher than conventional frequencies may include progressive decrease in alveolar minute ventilation, 20,21 auto-PEEP generation from gas trapping with subsequent overdistention of lungs, 29,30 and decrease in the mean airway pressure if adequate bias flow is not maintained. 21 Modern ventilators can achieve faster pressurization of the system as long as optimum inspiratory rise time is provided.…”

Section: Discussionmentioning

confidence: 99%

Feasibility of Mid-Frequency Ventilation Among Infants With Respiratory Distress Syndrome

et al. 2017

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Section: Discussionmentioning

confidence: 99%

Feasibility of Mid-Frequency Ventilation Among Infants With Respiratory Distress Syndrome

et al. 2017

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“…The force of contraction is directly proportional to the amount of stretch applied (19). Both applied PEEP and inadvertent PEEP may cause alveolar overdistension and increase functional residual capacity (10). This may exaggerate the rhythmic lung stretch that accompanies CPPB.…”

Section: Discussionmentioning

confidence: 99%

Air Trapping Causes a Ca2+-Channel-Mediated Increase in Pulmonary Vascular Resistance in Neonatal Lambs

1991

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ABSTRACT. Air trapping and alveolar hyperinflation may occur during mechanical ventilation in the presence of severe airway obstruction, during fast ventilator rates, and when expiratory time is compromised. Inadvertent positive end-expiratory pressure may occur with air trapping and increased mean airway pressure. The pulmonary artery pressure response to air trapping, produced during volumeregulated time-cycled ventilation, was studied in neonatal lamb lungs, isolated in situ, and perfused at a constant flow rate (50-75 ml . kg-'. min-'), both before and after Caz+-channel blockade with verapamil(5 mg). The hub of the endotracheal tube was narrowed to a 1.5-mm orifice to produce fixed proximal airway obstruction. Air trapping was then produced by lengthening inspiratory time from 25 to 80%, at zero end-expiratory pressure. The magnitude of inadvertent positive end-expiratory pressure due to air trapping was estimated by end-expiratory occlusion pressure. End-expiratory occlusion pressure was 0.20 ' 0.03 kPa (1.7 2 0.2 mm Hg) and 1.60 2 0.01 kPa (1 1.8 f 1.0 mm Hg), at 25 and 80% inspiratory times, respectively. On lengthening inspiratory time, mean pulmonary artery pressure (mPpa) increased briskly within 30 s followed by a gradual increase over the next 4 min. Verapamil blunted both the brisk and the gradual increase in mPpa on lengthening inspiratory time. Lengthening inspiratory time increased the mPpa by 2.0 2 0.1 kPa (14.7 f 0.8 mm Hg) from baseline, and verapamil reduced this increase to 1.3 f 0.1 kPa (10.1 f 0.6 mm Hg; p < 0.05 by analysis of variance). Verapamil did not affect changes in mean airway and peak inspiratory airway pressures and the magnitude of inadvertent positive end-expiratory pressure caused by lengthening inspiratory time. In the neonatal lamb, the Ca2+-channel-dependent portion of the mPpa response to air trapping amplifies the Ca2+-channel-independent portion, which represents the compressive effects of airway pressure on the pulmonary circulation. (Pediatr Res 29: 89-92,1991) Abbreviations PEEP, positive end-expiratory pressure CPPB, continuous positive pressure breathing PVR, pulmonary vascular resistance Ppa, pulmonary artery pressure mPpa, mean pulmonary artery pressure

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“…Cartwright et al [4] exam ined the effect of rapid ventilatory rates (30-120 breaths/min) on lung mechanics, using adult rabbits ventilated with a time-cycled, pressure-limited flow generator. Their data also indicated that gas trapping within the lung, as shown by the increase in FRC, was caused by increasing the ventilatory rate.…”

Section: Discussionmentioning

confidence: 99%

“…Simbruner and Gregory [12], using a lung model, and Cartwright et al [4], using rabbits, have shown that gas trapped within the lung increases functional residual capac ity (FRC) at rapid-rate ventilation. The present study was undertaken to ex amine the effect of rapid-rate ventilation, es pecially the effect of longer use, in normal and diseased lungs instilled with meconium.…”

mentioning

confidence: 99%

Effect of Rapid-Rate Ventilation on the Experimental Diseased Lung Caused by Meconium Aspiration

Obara¹,

Maekawa²,

Hamatani³

et al. 1985

Neonatology

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We compared rapid-rate ventilation using a conventional ventilator with slow-rate ventilation in the normal lung of 7 newborn pigs and in the diseased lung model instilled with 25% meconium solution into the trachea. The flow rate (7.5 1/min) and inspiratory:expiratory ratio (1:3) were kept constant during the experiments by using a constant-flow and time-cycled ventilator; the only change in settings was the rate. Transthoracic electrical impedance at end-expiration increased in the normal and in the diseased lung. Both mean intratracheal pressure and end-expiratory esophageal pressure increased significantly (p < 0.05) in both models upon changing to rapid-rate ventilation. Following the increase in ventilatory rates from an initial frequency of 37.5 breaths/min to a rapid rate of 150 breaths/min, there was a significant rise in both PaO₂ and PaCO₂ in the normal and diseased lung models. Although rapid-rate ventilation was maintained for 1 h, the improvement in oxygenation progressively deteriorated and PaCO₂ also increased further. This rise in PaCO₂ returned to the control levels by decreasing ventilation to the initial rate of 37.5/min. This study demonstrates that rapid-rate ventilation using a constant-flow and time-cycled ventilator is inferior to slow-rate ventilation in the diseased lung model.

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Functional residual capacity and lung mechanics at different levels of mechanical ventilation

Cited by 16 publications

References 0 publications

Feasibility of Mid-Frequency Ventilation Among Infants With Respiratory Distress Syndrome

Feasibility of Mid-Frequency Ventilation Among Infants With Respiratory Distress Syndrome

Air Trapping Causes a Ca2+-Channel-Mediated Increase in Pulmonary Vascular Resistance in Neonatal Lambs

Effect of Rapid-Rate Ventilation on the Experimental Diseased Lung Caused by Meconium Aspiration

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