Performance of respirators at fast rates commonly used in neonatal intensive care units

Greenough, Anne; Greenall, F

doi:10.1002/ppul.1950030512

Cited by 29 publications

(13 citation statements)

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“…More importantly, our data are in keeping with data generated from neonatal studies in which conventional ventilation applied at higher breathing frequencies with pressure control ventilation (similar to MFV) led to improved ventilation outcomes. 23,24 Our study demonstrated an increase in heart rate during the application of MFV, which, although not statistically significant, raises the concern for a decrease in stroke volume. Given the lower central venous pressure, stable airway, and pulmonary pressures, we suspect the cause was hypovolemia (decreasing central venous pressure through the study).…”

Section: Discussionmentioning

confidence: 92%

Application of Mid-Frequency Ventilation in an Animal Model of Lung Injury: A Pilot Study

et al. 2014

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BACKGROUND: Mid-frequency ventilation (MFV) is a mode of pressure control ventilation based on an optimal targeting scheme that maximizes alveolar ventilation and minimizes tidal volume (V T ). This study was designed to compare the effects of conventional mechanical ventilation using a lung-protective strategy with MFV in a porcine model of lung injury. Our hypothesis was that MFV can maximize ventilation at higher frequencies without adverse consequences. We compared ventilation and hemodynamic outcomes between conventional ventilation and MFV. METHODS: This was a prospective study of 6 live Yorkshire pigs (10 ؎ 0.5 kg). The animals were subjected to lung injury induced by saline lavage and injurious conventional mechanical ventilation. Baseline conventional pressure control continuous mandatory ventilation was applied with V T ‫؍‬ 6 mL/kg and PEEP determined using a decremental PEEP trial. A manual decision support algorithm was used to implement MFV using the same conventional ventilator. We measured P aCO 2 , P aO 2 , end-tidal carbon dioxide, cardiac output, arterial and venous blood oxygen saturation, pulmonary and systemic vascular pressures, and lactic acid. RESULTS: The MFV algorithm produced the same minute ventilation as conventional ventilation but with lower V T (؊1 ؎ 0.7 mL/kg) and higher frequency (32.1 ؎ 6.8 vs 55.7 ؎ 15.8 breaths/min, P < .002). There were no differences between conventional ventilation and MFV for mean airway pressures (16.1 ؎ 1.3 vs 16.4 ؎ 2 cm H 2 O, P ‫؍‬ .75) even when auto-PEEP was higher (0.6 ؎ 0.9 vs 2.4 ؎ 1.1 cm H 2 O, P ‫؍‬ .02). There were no significant differences in any hemodynamic measurements, although heart rate was higher during MFV. CONCLUSIONS: In this pilot study, we demonstrate that MFV allows the use of higher breathing frequencies and lower V T than conventional ventilation to maximize alveolar ventilation. We describe the ventilatory or hemodynamic effects of MFV. We also demonstrate that the application of a decision support algorithm to manage MFV is feasible.

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Section: Discussionmentioning

confidence: 92%

Application of Mid-Frequency Ventilation in an Animal Model of Lung Injury: A Pilot Study

et al. 2014

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“…Infants ventilated after 1 week of age frequently maintain a relatively rapid spontaneous respiratory rate [8] which is likely to result in a fast triggering rate. Unfortunately, the SLE ventilator is known to malfunction at very fast rates [2] and this could have impaired gas exchange.…”

Section: Discussionmentioning

confidence: 99%

Patient triggered ventilation in chronically ventilator-dependent infants

Hird

Greenough

1991

Eur J Pediatr

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Patient triggered ventilation (PTV) has been assessed as a method of respiratory support in infants remaining ventilator-dependent beyond the 1st week of life. Sixteen preterm infants were studied who had a median gestational age of 26 weeks and postnatal age of 22 days. PTV was delivered using a ventilator incorporating an airway pressure trigger. PTV was only successfully maintained until extubation in 3 infants, failing to provide a satisfactory method of respiratory support in the remaining 13 infants after a median of 1 h (range 1-10). One of the 13 infants was persistently asynchronous at 1 h despite manipulation of inflation time. The other 12 infants, at failure of PTV, were making respiratory efforts which were inadequate to consistently trigger the ventilator. Infants in whom PTV was successful were older, more mature and of greater birth weight; the trigger delay at 1 h was significantly shorter in this group (P less than 0.05). A predictor of failure of PTV was asynchrony in the 1st h after commencing PTV (P less than 0.02). We conclude PTV incorporating an airway pressure trigger infrequently provides a useful method of respiratory support in infants who are chronically ventilator-dependent.

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“…Reduction in flow would, however, adversely affect ventilator waveform, particularly if short inflation times were being used. 7 We conclude other triggering systems and forms of patient triggered ventilation need to be urgently evaluated. In the meanwhile, we recommend that the airway pressure trigger should be used for neonatal patient triggered ventilation in preference to the Graseby MRIO respiration monitor.…”

Section: Discussionmentioning

confidence: 96%