Ventilated Infants Have Increased Dead Space and Lower Alveolar Tidal Volumes during the Early versus Recovery Phase of Respiratory Distress

Abstract

Background: Few studies have reported the measurement of anatomical dead space (V d,an) and alveolar tidal volume (V A) in ventilated neonates with respiratory distress. Objective: The aim of this study was to determine the differences in V d,an and V A in ventilated infants between the early and recovery phases of respiratory distress using volumetric capnography (V cap) based on ventilator graphics and capnograms. Methods: This study enrolled twenty-five ventilated infants (mean birth weight, 2,220 ± 635 g; mean gestational age, 34.7 ± 3.3 weeks). We adjusted respiratory settings to maintain appropriate oxygenation and tidal volume (V T), and performed V cap based on waveforms of ventilator graphics and capnograms. V d,an and V A were measured in infants with respiratory disorders, immediately after intubation (early phase) and subsequently when they were clinically stable (recovery phase). Results: The early phase, with lower dynamic lung compliance, required a higher level of ventilator support, not positive end-expiratory pressure, than the recovery phase. There were significant differences between the early and recovery phases for V d,an

Large difference between Enghoff and Bohr dead space in ventilated infants with hypoxemic respiratory failure

“…Our method of waveform sampling and drawing a volumetric capnogram based on the waveforms have been described previously. 8 In brief, we simultaneously obtained the capnogram waveforms of cap-ONE and the volume waveforms of the ventilator by using a screen capture program with the ventilator parameters. Subsequently, we manually superimposed the capnogram and volume waveforms at the beginning of inspiration and measured the P E CO 2 and expired tidal volume (V T,E ) at the same time points (30-50 points from the start to the end of expiration) by using ImageJ (http://rsb.info.nih.gov/ij/); P E CO 2 was plotted against V T,E for a single breath.…”

“…We had previously reported the use of volumetric capnography based on ventilator graphics and capnograms in ventilated neonates in NICUs by using a commonly used lightweight mainstream capnometer. 8,9 We hypothesized that ventilated infants with hypoxemic respiratory failure (HRF) show a large difference between V d, Enghoff and V d, Bohr . Thus, the objective of this study was to measure both V d, Enghoff and V d, Bohr, and to detect low V/Q mismatch and right-to-left shunting in intubated neonates by using volumetric capnography based on ventilator graphics and capnograms.…”

Reduction in minute alveolar ventilation causes hypercapnia in ventilated neonates with respiratory distress

“…While ventilated neonates received arterial blood sampling necessary for treatment, we simultaneously obtained the capnogram waveforms of cap-ONE and volume waveforms of the ventilator in the supine position, using a screen capture programme, with ventilator parameters. Our method of analysis has previously been described [5]. Briefly, we manually superimposed the capnogram waveforms and volume waveforms at the beginning of inspiration, and measured the P E CO 2 and V T,E values at the same time at 30-50 points from the start to the end of expiration using ImageJ software (http://rsb.info.nih.gov/ij/).…”

“…This method employs a plot of expiratory CO 2 (P E CO 2 ) versus expired tidal volume (V T,E ), and specialised equipment with effective apparatus dead space for newborns with low V T [4]. We have previously reported the analysis of V cap using ventilator graphics and capnograms with low dead-space cap-ONE (Nihon Kohden, Tokyo, Japan) mainstream capnometers [5].…”