High-frequency ventilation for non-invasive respiratory support of neonates

Abstract

Non-invasive respiratory support is increasingly used in lieu of intubated ventilator support for the management of neonatal respiratory failure, particularly in very low birth weight infants at risk for bronchopulmonary dysplasia. The optimal approach and mode for non-invasive support remains uncertain. This article reviews the application of high-frequency ventilation for non-invasive respiratory support in neonates, including basic science studies on mechanics of gas exchange, animal model investigations, and a review of current clinical use in human neonates.

Keywords: High frequency; Neonatal; Non-invasive; Respiratory.

Fig. 1

Interactive factors contributing to delivered tidal volume (V_T) and effectiveness of gas exchange during non-invasive high-frequency nasal ventilation. I:E, inspiratory to expiratory ratio; ΔP, pressure amplitude. NIPPV, nasal intermittent positive pressure ventilation.

Fig. 2

Variable effect of pressure amplitude (ΔP), frequency (f), and nasal prong size on tidal volume (V_T) delivery during test-lung simulated high-frequency nasal ventilation. (a) At a fixed frequency (10 Hz) and mean airway pressure (10 cmH₂O), increasing ΔP is accompanied by increasing V_T with an apparent plateau effect around 70% maximum amplitude. There is a significant increase in V_T when the I:E ratio is increased from 33% to 50%. (Adapted with permission from De Luca et al. [20].) (b) With a set I:E ratio and ΔP, increasing high frequency breath rate is accompanied by decreasing V_T. The effect on V_T is affected by the caliber of the nasal prong interface. High frequency via 3100A (CareFusion, San Diego, CA, USA). (Adapted with permission from De Luca et al. [19].)

Fig. 3

Comparison of relative effectiveness of gas exchange by non-invasive mode (nasal intermittent positive pressure ventilation (NIPPV) vs high-frequency nasal ventilation (HFNV)). High frequency rate has a significant impact on the effectiveness of gas exchange in a test-lung model, with apparent optimal rate for this model at 8 Hz. High frequency via VN500 (Dräger Medical, Lübeck, Germany). (Adapted from Ref. [21].)

Fig. 4

Effect of nasal prong size, amplitude (ΔP) and frequency (f) on delivered tidal volume in lung simulated high-frequency nasal ventilation via a Bronchotron high-frequency ventilator (Percussionaire, Sand Point, ID, USA). Delivered tidal volume is significantly decreased at lower ΔP and at higher f. Nasal interface via variously sized Hudson (H) nasal CPAP prongs (Hudson-RCI, Temecula, CA, USA). (Unpublished data.)

Fig. 5

Physiologic targets for arterial blood gases in premature lambs supported for 21 days by invasive mechanical ventilation (IMV; VIP Bird, CareFusion, San Diego, CA, USA) or two approaches to non-invasive high-frequency nasal ventilation (NIV): VDR4 (Percussionaire, Sand Point, ID, USA) or VN500 (Dräger Medical, Lübeck, Germany). Our model prospectively targets arterial oxygenation (PaO₂) range between 60 and 90 mmHg and ventilation (PaCO₂) range between 45 and 60 mmHg. At day-of-life 6, either mode of NIV respiratory support required ~10% lower F_iO₂ to maintain the targeted PaO₂ range compared to IMV respiratory support. Pressure setting for peak inspiratory pressure (PIP) at the ventilators was comparable among IMV and both NIV modes of respiratory support, but PIP at the ventilator is not the same as mean intra-tracheal pressure during NIV. (See Fig. 7; adapted with permission from Null et al. [25].)

Fig. 6

Graphic representation of in-vivo data from preterm lambs supported by high-frequency nasal ventilation via VDR4 high-frequency ventilator (Percussionaire, Sand Point, ID, USA). (A) High-frequency pressure pulsations are seen throughout both the inspiratory (solid white arrow) and expiratory (dashed white arrow) phases of background convective breaths. (B) Change in peak delivered pressure and convective tidal volume following increased high-frequency pressure amplitude. (C) Measured tidal volume by respiratory inductive plethysmography (Respitrace, CareFusion, San Diego, CA, USA) during convective breaths with simultaneous pressure recordings via Samba 3200 fiberoptic micropressure transducer (Harvard Apparatus Canada, Saint-Laurent, QC, Canada) integrated with a BIOPAC MP150 system (BIOPAC Systems, Goleta, CA, USA) and inserted into posterior nasopharyngeal space.

Fig. 7

Pressure measurements in premature lambs supported by high-frequency nasal ventilation (HFNV) via the VDR4 (Percussionaire, Sand Point, ID, USA) across the spectrum from ventilator output (Vent) to the connection of the ventilator circuit to the nasopharyngeal tube interface (Conn), then beyond the tube within the nasopharyngeal space or within the trachea. (Adapted with permission from Null et al. [25].) Measurements were made at two different set peak inspiratory pressure (PIP) settings (high ~27 cmH₂O, or moderate PIP ~14 cmH₂O). At both high (A) and medium (C) PIP there was ~70% pressure attenuation across the tube interface, but there was essentially no pressure loss from the nasopharynx to mid trachea. Similar pressure decrements are seen for mean airway pressures (B and D) with persistent positive, low positive end expiratory pressure maintained during HFNV in spontaneously breathing neonatal lambs.

Fig. 8

Histopathology at 21 days of preterm lambs (131 days) supported by (a) invasive mechanical ventilation (IMV) or (b) non-invasive high-frequency nasal ventilation (HFNV). The terminal respiratory unit (TRU) is dilated and non-uniform in MV animals compared to HFNV lambs. Blunted secondary crest formation is seen in the lungs of MV lambs (large arrowhead, a) but numerous well-developed secondary crests are noted in the HFNV lambs (large arrowhead, b). The arrows point to thickened saccular/alveolar walls in the lambs managed by IMV contrasted to thin distal airspace walls in the HFNV lambs.

Fig. 9

Monitor view showing waveforms and variable settings interfaced with VDR4 (Percussionaire, Sand Point, ID, USA) for HFNV support. The oscillatory pressure pulses are delivered continuously throughout both the inspiratory phase of convective breaths as well as during the expiratory or CPAP phase. The pressure measurements are obtained proximally at the ventilator, not at or beyond the nasal prong interface.

Fig. 10

Configuration of the “phasitron” to the “turbohub” for non-invasive respiratory support with the VDR4 or Bronchotron ventilators (Percussionaire, Sand Point, ID, UT, USA).