Effect of pressure rise time on ventilator parameters and gas exchange during neonatal ventilation

Abstract

Background Pressure rise time (PRT), also known as slope time to the peak inflating pressure can be set on some modern neonatal ventilators. On other ventilators, PRT is determined by the set circuit flow. Changing slope time can affect mean airway pressure (MAP), oxygenation, and carbon dioxide elimination. Our aim was to investigate the effect of PRT on ventilator parameters and gas exchange during volume‐guaranteed ventilation. Methods In a crossover study, 12 infants weighing greater than 2 kg were ventilated using a Dräger Babylog VN500 ventilator with synchronized intermittent positive pressure ventilation with volume guarantee (SIPPV‐VG) and pressure support ventilation with volume guarantee (PSV‐VG). During both modes PRTs between 0.08 and 0.40 seconds were used in 15‐minute epochs. Data from the ventilator and patient monitors were downloaded with 1‐ and 100‐Hz sampling rate and analyzed using the Python computer language. Results During PSV‐VG, longer PRTs were associated with longer inspiratory time (P < .0001) and with lower peak inflating pressure (PIP; P = .003), but the MAP was similar. During SIPPV‐VG the PIP was not significantly different; however, MAP was lower with longer PRT (P = .001). With a short PRT (0.08 seconds), the PIP was higher during PSV‐VG than during SIPPV‐VG (19.8 vs 16.5 mbar; P = .042). There were no significant differences in tidal volume delivery, respiratory rate, minute volume, oxygen saturations, or end‐tidal CO2 with different PRTs in either mode. Conclusions During SIPPV‐VG or PSV‐VG, using short or long PRTs affects some ventilation parameters but does not significantly change oxygenation or carbon dioxide elimination.

Effect of flow-optimized pressure control ventilation-volume guaranteed (PCV-VG) on postoperative pulmonary complications: a consort study

“…Moreover, the respiratory mechanics-related parameters improved, which is consistent with previous reports [ 24 , 27 ]. As reported by Chong et al, the respiratory parameters did not improve significantly although some of the ventilation parameters did improve significantly [ 23 ]. Mechanical ventilation increased the expression of NLRP3 mRNA in alveolar macrophages and caused lung inflammation dependent on NLRP3 inflammatory bodies [ 28 , 29 ].…”

“…When using the Ingmar ASL5000 in a study to create a passive two-compartment lung model, increasing the IRT helps to balance inspiratory pressure, chamber-specific tidal volume, and volume equilibrium [ 22 ]. A study involving 12 infants weighing over 2 kg indicated that varying IRTs during synchronized intermittent positive pressure ventilation or PCV-VG impacted specific ventilation parameters but did not significantly affect oxygenation and carbon dioxide output [ 23 ]. Extending the duration of time spent inhaling helped sustain the rise in alveolar pressure, decrease the dead space, enhance arterial oxygen levels and respiratory performance, optimize gas exchange and arterial oxygen levels, and lower the airway pressure [ 24 ].…”

Computational analysis of neonatal ventilator waveforms and loops

“…The clinical significance of different PRTs in neonatal ventilation is uncertain. 20 We have also found that a significant proportion of ventilator inflations during AC-VG ventilation contain periods of inspiratory hold or contains no expiratory hold, the occurrence and significance of which in neonates are not known as there are few studies analysing short periods. 21 Ventiliser allows for quantitative analysis of inflations over long periods and will facilitate such studies in future.…”