In vitro assessment of proportional assist ventilation

Patel, Deena-Shefali; Rafferty, Gerrard F.; Hannam, Simon; Lee, Silke; Milner, Anthony; Greenough, Anne

doi:10.1136/adc.2009.170787

Cited by 10 publications

(14 citation statements)

References 23 publications

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“…Although the infants currently studied were all ventilator dependent beyond 1 week after birth, their respiratory system resistances were not found, on average, to be very high; the median respiratory system resistance was 86.5 (range 85–174) cm H 2 O/L/s. We have previously demonstrated that the likelihood of oscillations appearing in the airway pressure waveform was greater when elastic unloading was used in a low compared with a high resistance model 5. In addition, in the in vitro model,5 oscillations in the airway pressure waveform appeared when the resistive unloading was greater than 100 cm H 2 O/L/s.…”

Section: Methodsmentioning

confidence: 96%

“…If after 10 min the infant remained stable and no airway pressure waveform abnormalities were observed, the unloading was increased to 100%. If airway pressure waveform abnormalities were then noted,5 the unloading was reduced back to 75%. Although the infants currently studied were all ventilator dependent beyond 1 week after birth, their respiratory system resistances were not found, on average, to be very high; the median respiratory system resistance was 86.5 (range 85–174) cm H 2 O/L/s.…”

Section: Methodsmentioning

confidence: 99%

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Crossover study of proportional assist versus assist control ventilation

Bhat

Patel

Hannam

et al. 2014

Arch Dis Child Fetal Neonatal Ed

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Objective To test the hypothesis that in very prematurely born infants remaining ventilated beyond the first week, proportional assist ventilation (PAV) compared with assist control ventilation (ACV) would be associated with reduced work of breathing, increased respiratory muscle strength and less ventilator-infant asynchrony which would be associated with improved oxygenation. Design Randomised crossover study. Setting Tertiary neonatal unit. Patients 12 infants with a median gestational age of 25 (range 24-26) weeks were studied at a median of 43 (range 8-86) days. Interventions Infants were studied for 1 h each on PAV and ACV in random order. Main outcome measures At the end of each hour, the work of breathing (assessed by measuring the diaphragmatic pressure time product), thoracoabdominal asynchrony and respiratory muscle strength (maximal inspiratory pressure, maximal expiratory pressure (Pemax) and maximal transdiaphragmatic pressure (Pdimax)) were assessed. Blood gas analysis was performed and the oxygenation index (OI) calculated.Results After 1 h on PAV compared with 1 h on ACV, the median OI (5.55 (range 5-11) vs 10.10 (range 7-16), p=0.002) and PTP levels were lower (217 (range

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Section: Methodsmentioning

confidence: 96%

Section: Methodsmentioning

confidence: 99%

Crossover study of proportional assist versus assist control ventilation

Bhat

Patel

Hannam

et al. 2014

Arch Dis Child Fetal Neonatal Ed

View full text Add to dashboard Cite

show abstract

“…Full unloading was the level of unloading which increased the infant's compliance to the expected 'normal', that is, 2.0 mL/ cm H 2 O/kg. If after 10 min the infant remained stable and no airway pressure waveform abnormalities were observed [4], the unloading was increased to 100 %. If airway pressure waveform abnormalities were then noted by looking at the pressure display, the unloading was to be reduced back to 75 %.…”

Section: Methodsmentioning

confidence: 99%

“…If airway pressure waveform abnormalities were then noted by looking at the pressure display, the unloading was to be reduced back to 75 %. Resistive unloading was not used as, an in vitro model, oscillations in the airway pressure waveforms appeared when the resistive unloading was greater than 100 cm H 2 O/L/s [4].…”

Section: Methodsmentioning

confidence: 99%

“…During PAV, the applied pressure is servo controlled throughout each breath, whereas during ACV, only the initiation of inflation is sycnchronised to the start of inspiration; hence, we hypothesised that oxygenation would be superior on PAV compared to ACV. During PAV, however, we have demonstrated a trigger delay of 60 ms using an in vitro model [4]; hence, it was important to assess blood gases over a longer period that studied previously [1]. The aim of this study, therefore, was to test the hypothesis that infants with evolving or established BPD would have superior oxygenation index results after 4 h on PAV compared to after a similar period on ACV.…”

Section: Introductionmentioning

confidence: 99%

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Proportional assist versus assist control ventilation in premature infants

et al. 2015

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During proportional assist ventilation (PAV), the applied pressure is servo-controlled based on continuous input from the infant's breathing. In addition, elastic and resistive unloading can be employed to compensate for the abnormalities in the infant's lung mechanics. The aim of this study was to test the hypothesis that in very prematurely born infants remaining ventilated beyond the first week, PAV compared to assist control ventilation (ACV) would be associated with superior oxygenation. A randomised crossover study was undertaken. Infants were studied for 4 hours each on PAV and ACV in random order; at the end of each 4-h period, the oxygenation index (OI) was calculated. Eight infants, median gestational age of 25 (range 24-33) weeks, were studied at a median of 19 (range 10-105) days. It had been intended to study 18 infants but as all the infants had superior oxygenation on PAV (p=0.0039), the study was terminated after recruitment of eight infants. The median inspired oxygen concentration (p=0.049), mean airway pressure (p=0.012) and OI (p= 0.012) were all lower on PAV. Conclusion:These results suggest that PAV compared to ACV is advantageous in improving oxygenation for prematurely born infants with evolving or established BPD. What is known:•During proportional assist ventilation (PAV), the applied pressure is servo controlled throughout each spontaneous breath.•Elastic and resistive unloading can compensate for the infant's abnormalities in lung mechanics. What is new:•In a randomised crossover study, infants with evolving/established BPD were studied on PAV and ACV each for 4 h. •The oxygenation index was significantly lower on PAV in all infants studied.

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Proportional assist and neurally adjusted ventilation: Clinical knowledge and future trials in newborn infants

Sindelar

McKinney

Wallström

et al. 2021

Pediatric Pulmonology

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Different types of patient triggered ventilator modes have become the mainstay of ventilation in term and preterm newborn infants. Maintaining spontaneous breathing has allowed for earlier weaning and the additive effects of respiratory efforts combined with pre‐set mechanical inflations have reduced mean airway pressures, both of which are important components in trying to avoid lung injury and promote normal lung development. New sophisticated modes of assisted ventilation have been developed during the last decades where the control of ventilator support is turned over to the patient. The ventilator detects the respiratory effort and adjusts ventilatory assistance proportionally to each phase of the respiratory cycle, thus enabling the patient to have full control of the start, the duration and the amount of ventilatory assistance. In this paper we will review the literature on the ventilatory modes of proportional assist ventilation and neurally adjusted ventilatory assistance, examine the different ways the signals are analyzed, propose future studies, and suggest ways to apply these modes in the clinical environment.

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In vitro assessment of proportional assist ventilation

Abstract: During PAV, unloading does reduce inspiratory load, but there are wave form abnormalities and a time lag in delivery of the inflation pressure. The impact of these problems needs careful evaluation in the clinical setting.

Cited by 10 publications

References 23 publications

Crossover study of proportional assist versus assist control ventilation

Crossover study of proportional assist versus assist control ventilation

Proportional assist versus assist control ventilation in premature infants

Proportional assist and neurally adjusted ventilation: Clinical knowledge and future trials in newborn infants

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