Effects of different flow patterns and end-inspiratory pause on oxygenation and ventilation in newborn piglets: an experimental study

Abstract

BackgroundHistorically, the elective ventilatory flow pattern for neonates has been decelerating flow (DF). Decelerating flow waveform has been suggested to improve gas exchange in the neonate when compared with square flow (SF) waveform by improving the ventilation perfusion. However, the superiority of DF compared with SF has not yet been demonstrated during ventilation in small infants. The aim of this study was to compare SF vs. DF, with or without end-inspiratory pause (EIP), in terms of oxygenation and ventilation in an experimental model of newborn piglets.MethodsThe lungs of 12 newborn Landrace/LargeWhite crossbred piglets were ventilated with SF, DF, SF-EIP and DF-EIP. Tidal volume (VT), inspiratory to expiratory ratio (I/E), respiratory rate (RR), and FiO2 were keep constant during the study. In order to assure an open lung during the study while preventing alveolar collapse, a positive end-expiratory pressure (PEEP) of 6 cmH2O was applied after a single recruitment maneuver. Gas exchange, lung mechanics and hemodynamics were measured.ResultsThe inspiratory flow waveform had no effect on arterial oxygenation pressure (PaO2) (276 vs. 278 mmHg, p = 0.77), alveolar dead space to alveolar tidal volume (VDalv/VTalv) (0.21 vs. 0.19 ml, p = 0.33), mean airway pressure (Pawm) (13.1 vs. 14.0 cmH2O, p = 0.69) and compliance (Crs) (3.5 vs. 3.5 ml cmH2O−1, p = 0.73) when comparing SF and DF. A short EIP (10%) did not produce changes in the results.ConclusionThe present study showed that there are no differences between SF, DF, SF-EIP and DF-EIP in oxygenation, ventilation, lung mechanics, or hemodynamics in this experimental model of newborn piglets with healthy lungs.

Implementing a Thoracic Enhanced Recovery Program: Lessons Learned in the First Year

“…Minimum positive end-expiratory pressure (PEEP) was standardized at 5 cm H 2 O unless the patient had severe chronic obstructive pulmonary disease or clinical evidence of auto-PEEP. Ideal PEEP was determined on a standardized PEEP decrement trial as previously described [15]. Isotonic crystalloids were used to treat hypotension in fluid responsive patients; vasoactive agents were used in patients deemed to be euvolemic.…”

The Effects of Pressure-Versus Volume-Controlled Ventilation on Ventilator Work of Breathing

“…Roth et al [25] reported that decelerating inspiratory flow had no beneficial effects on pulmonary gas exchange when compared with the square inspiratory flow while an increase in mean airway pressure in pressure-controlled ventilation may raise the potential risk of VILI. Some other experimental studies [26,27] showed that there are no differences between square or decelerating flow waveform in oxygenation. Antonaglia et al mathematical model [28] showed that both ventilatory modes provided similar gas distribution, but in square flow, peak pressures were higher in the sicker compartment respect to decelerating flow.…”

The effects of pressure- versus volume-controlled ventilation on ventilator work of breathing

“…Roth et al [25] reported that decelerating inspiratory flow had no beneficial effects on pulmonary gas exchange when compared with the square inspiratory flow while an increase in mean airway pressure in pressure-controlled ventilation may raise the potential risk of VILI. Some other experimental studies [26,27] showed that there are no differences between square or decelerating flow waveform in oxygenation. Antonaglia et al mathematical model [28] showed that both ventilatory modes provided similar gas distribution, but in square flow, peak pressures were higher in the sicker compartment with respect to decelerating flow.…”