High Frequency Oscillatory Ventilation Combined With Intermittent Sigh Breaths: Effects on Lung Volume Monitored by Electric Tomography Impedance.

Summary

Background Ventilator induced lung injury (VILI) remains a problem in neonatology. High frequency oscillatory ventilation (HFOV) provides effective gas exchange with minimal pressure fluctuation around a continuous distending pressure and therefore small tidal volume. Animal studies showed that recruitment and maintenance of functional residual capacity (FRC) during HFOV ("open lung concept") could reduce lung injury.

"Open lung HFOV" is achieved by delivering a moderate high mean airway pressure (MAP) using oxygenation as a guide of lung recruitment. Some neonatologists suggest combining HFOV with recurrent sigh-breaths (HFOV-sigh) delivered as modified conventional ventilator-breaths at a rate of 3/min. The clinical observation is that HFOV-sigh leads to more stable oxygenation, quicker weaning and shorter ventilation. This may be related to improved lung recruitment.

Electric Impedance Tomography (EIT) enables measurement and mapping of regional ventilation distribution and end-expiratory lung volume (EELV). EIT generates cross-sectional images of the subject based on measurement of surface electrical potentials resulting from an excitation with small electrical currents and has been shown to be a valid and safe tool in neonates.

Purpose, aims:

* To compare HFOV-sigh with HFOV-only and determine if there is a difference in global and regional EELV (primary endpoints) and spatial distribution of ventilation measured by EIT
* To provide information on feasibility and treatment effect of HFOV-sigh to assist planning larger studies. We hypothesize that EELV during HFOV-sigh is higher, and that regional ventilation distribution is more homogenous.

Methods:

Infants at 24-36 weeks corrected gestational age already on HFOV are eligible. Patients will be randomly assigned to HFOV-sigh (3 breaths/min) followed by HFOV-only or vice versa for 4 alternating 1-hours periods (2-treatment, double crossover design, each patient being its own control). During HFOV-sigh set-pressure will be reduced to keep MAP constant, otherwise HFOV will remain at pretrial settings.

16 ECG-electrodes for EIT recording will be placed around the chest at study start. Each recording will last 180s, and will be done at baseline and at 30 and 50 minutes after each change in ventilator modus.

Feasibility No information of EIT-measured EELV in babies on HFOV-sigh exists. This study is a pilot-trial.

In a similar study-protocol of lung recruitment during HFOV-sigh using "a/A-ratio" as outcome, 16 patients was estimated to be sufficient to show an improvement by 25%. This assumption was based on clinical experience in a unit using HFOV-sigh routinely. As the present study examines the same intervention we assume that N=16 patients will be a sufficient sample size. We estimate to include this number in 6 months.

Conditions

• Respiratory Distress Syndrome In Premature Infants
• Bronchopulmonary Dysplasia
• Ventilator-Induced Lung Injury
• Functional Residual Capacity

Interventions

OTHER

HFOV combined with sigh breaths

It is planned only to investigate infants already ventilated on the HFOV-modus on high frequency oscillators, where the HFOV modus can be superimposed on conventional modes of ventilation. This gives the opportunity to combine HFOV with intermittent sigh breaths with a pre-set frequency and pre-set peak inspiratory pressure (PIP) and thus comparing HFOV combined with sigh breaths (HFOV-sigh) with conventional HFOV (HFOV-only). All included participants will be exposed to the two different ventilator strategies tested in this trial, albeit in alternating and different order. Each patient will serve, as it's own control. The trial will involve four alternating 1-hours periods allowing a sufficient "wash-out" period, as it has been shown that alveolar recruitment and derecruitment may take up to 25 min after changes to ventilator pressures At study start the patients will randomly be assigned to either starting with HFOV-only or HFOV-sigh

Sponsors & Collaborators

• Rigshospitalet, Denmark

  lead OTHER

Principal Investigators

• Christian Heiring, neonatologist · Department of Neonatology, Rigshospitalet, Copenhagen

• Luke Jardine, neonatologist · Department of Neonatology, Mater Mothers Hospital, Brisbane, Australia

Study Design

Allocation

RANDOMIZED

Purpose

TREATMENT

Masking

NONE

Model

CROSSOVER

Eligibility

Min Age

24 Weeks

Max Age

44 Weeks

Sex

ALL

Healthy Volunteers

No

Timeline & Regulatory

Start

2014-01-31

Primary Completion

2018-07-31

Completion

2023-01-01

Countries

• Australia

Study Locations