Reduction of Endotracheal Tube Connector Dead Space Improves Ventilation: A Bench Test on a Model Lung Simulating an Extremely Low Birth Weight Neonate

Abstract

BACKGROUND: The reduction of instrumental dead space is a recognized approach to preventing ventilation-induced lung injury in premature infants. However, there are no published data regarding the effectiveness of instrumental dead-space reduction in endotracheal tube (ETT) connectors. We tested the impact of the Y-piece/ETT connector pairs with reduced instrumental dead space on CO 2 elimination in a model of the premature neonate lung. METHODS: The standard ETT connector was compared with a low-dead-space ETT connector and with a standard connector equipped with an insert. We compared the setups by measuring the CO 2 elimination rate in an artificial lung ventilated via the connectors. The lung was connected to a ventilator via a standard circuit, a 2.5-mm ETT, and one of the connectors under investigation. The ventilator was run in volume-controlled continuous mandatory ventilation mode. RESULTS: The low-dead-space ETT connector/Y-piece and insert-equipped standard connector/Y-piece pairs had instrumental dead space reduced by 36 and 67%, respectively. With set tidal volumes (V T ) of 2.5, 5, and 10 mL, in comparison with the standard ETT connector, the low-dead-space connector reduced CO 2 elimination time by 4.5% (P < .05), 4.4% (P < .01), and 7.1% (not significant), respectively. The insert-equipped standard connector reduced CO 2 elimination time by 13.5, 25.1, and 16.1% (all P < .01). The low-dead-space connector increased inspiratory resistance by 17.8% (P < .01), 9.6% (P < .05), and 5.0% (not significant); the insert-equipped standard connector increased inspiratory resistance by 9.1, 8.4, and 5.9% (all not significant). The low-dead-space connector decreased expiratory resistance by 6.8% (P < .01) and 1.8% (not significant) and increased it by 1.4% (not significant); the insert-equipped standard connector decreased expiratory resistance by 1.5 and 1% and increased it by 1% (all not significant). The low-dead-space connector increased work of breathing by 4.7% (P < .01), 3.8% (P < .01), and 2.5% (not significant); the insert-equipped standard connector increased it by 0.8% (not significant), 2.5% (P < .01), and 2.8% (P < . IntroductionVentilator-induced lung injury is considered an important causative factor in the pathophysiology of bronchopulmonary dysplasia (BPD) in premature infants. 1 Limiting ventilator-associated lung overdistention/damage is a well-recognized approach for the prevention of BPD, but Dr Ivanov is affiliated with the Section

Effects of a closed system suction connector on airwayresistance in ventilated neonates

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“…Recently, Ivanov reported the importance of reduction in the instrumental dead space for improvement of ventilation in their bench study. The authors demonstrated when the dead space in ETT connectors was decreased artificial lung ventilation improved, even though a slight increase in airway resistance and work of breathing occurred (6). Authors commented on this conflicting finding as the increase in resistance and work of breathing may affect patients especially during weaning as the importance of reduction in the instrumental dead space during weaning was previously emphasized (9).…”

“…We found no statistical data regarding standard deviations of measurements of resistances in in vivo studies and therefore we used the data from the in vitro study by Ivanov et al as a reference to calculate the necessary number of breaths/period for each case (6). We assume that the standard deviation will be larger as this is an in vivo study; therefore we used twice the reference's standard deviation value for power analyses.…”

Preclinical Trial of the Effectiveness of the Safety Nasogastric Tube to Detecting Tube Position Based on Tidal Volume and Pepsin Assay Results in the Gastrointestinal Tract of Macaca Fascicularis

“…According to Ivanov (2015), the loss of air in the equipment can interfere with the amount of gas exchange that is expected to occur. Even a loss of space that is too large can match the TV [29]. Thus, the SNGT requires an airbag with a volume smaller than the TV to allow for easier observation of airbag movement.…”

An in vitro evaluation of the influence of neonatal endotracheal tube diameter and length on the work of breathing

“…To avoid this problem, some clinicians shorten ETTs, which may improve the CO 2 elimination . The shorter‐ and/or wider‐ID ETTs reduce resistance and the shorter one reduces respiratory dead space, presumably leading to decreased work of breathing (WOB) in newborn babies . Mohr et al have recently conducted an in vitro study to quantitate the effect of ETT shortening on WOB in simulated neonatal and pediatric lung models.…”