Abstract
Non-invasive intermittent positive pressure ventilation can lead to esophageal insufflations and in turn to gastric distension. The fact that the latter induces transient relaxation of the lower esophageal sphincter implies that it may increase gastroesophageal refluxes. We previously reported that nasal Pressure Support Ventilation (nPSV), contrary to nasal Neurally-Adjusted Ventilatory Assist (nNAVA), triggers active inspiratory laryngeal closure. This suggests that esophageal insufflations are more frequent in nPSV than in nNAVA. The objectives of the present study were to test the hypotheses that: i) gastroesophageal refluxes are increased during nPSV compared to both control condition and nNAVA; ii) esophageal insufflations occur more frequently during nPSV than nNAVA. Polysomnographic recordings and esophageal multichannel intraluminal impedance pHmetry were performed in nine chronically instrumented newborn lambs to study gastroesophageal refluxes, esophageal insufflations, states of alertness, laryngeal closure and respiration. Recordings were repeated without sedation in control condition, nPSV (15/4 cmH2O) and nNAVA (~ 15/4 cmH2O). The number of gastroesophageal refluxes recorded over six hours, expressed as median (interquartile range), decreased during both nPSV (1 (0, 3)) and nNAVA [1 (0, 3)] compared to control condition (5 (3, 10)), (p < 0.05). Meanwhile, the esophageal insufflation index did not differ between nPSV (40 (11, 61) h-1) and nNAVA (10 (9, 56) h-1) (p = 0.8). In conclusion, nPSV and nNAVA similarly inhibit gastroesophageal refluxes in healthy newborn lambs at pressures that do not lead to gastric distension. In addition, the occurrence of esophageal insufflations is not significantly different between nPSV and nNAVA. The strong inhibitory effect of nIPPV on gastroesophageal refluxes appears identical to that reported with nasal continuous positive airway pressure.
Highlights
Non-invasive ventilatory support, either continuous or intermittent positive airway pressure, has been associated with the insufflation of gas into the esophagus and in turn to gastric distension in subjects of all ages [1,2,3,4]
We have previously shown that application of an nCPAP of 6 cmH2O, which did not appear to be associated with gastric distension, virtually abolished gastroesophageal refluxes (GER) in lambs [6]; importantly, this result is in agreement with previous reports on nCPAP in adult humans [7]
We aimed to provide direct documentation of esophageal insufflations during nIPPV and to investigate whether: i) esophageal insufflations are increased in nPSV compared to nasal Neurally-Adjusted Ventilatory Assist (nNAVA); ii) the number of esophageal insufflations is related to the number of GERs in nPSV and nNAVA, and iii) esophageal insufflations during nPSV are increased during the period of active laryngeal closure
Summary
Non-invasive ventilatory support, either continuous (nCPAP) or intermittent (nIPPV) positive airway pressure, has been associated with the insufflation of gas into the esophagus and in turn to gastric distension in subjects of all ages [1,2,3,4]. We have previously shown that application of an nCPAP of 6 cmH2O, which did not appear to be associated with gastric distension, virtually abolished GERs in lambs [6]; importantly, this result is in agreement with previous reports on nCPAP in adult humans [7]. Given that peak inspiratory pressure during nIPPV is most often well above 6 cmH2O, even in newborns [3], it would seem logical to assume that nIPPV will further promote gastric distension and GERs compared to nCPAP
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