Impact of Current Volume Under High-rate Nasal Oxygen Therapy During Acute Hypoxemic Respiratory Failure de Novo

Summary

De novo acute hypoxemic respiratory failure (AHRF) is associated with high overall mortality, which increases significantly with the use of orotracheal intubation. High flow nasal canula (HFNC) has turned to be the first line non-invasive oxygenation strategy aiming to avoid intubation. One of the main factors worsening lung injury and increasing mortality in invasively ventilated patients is a too high tidal volume (TV) delivered by the ventilator. Consistent data suggest that such an aggravation of respiratory lesions may occur during spontaneous ventilation if TV is too large. This phenomenon is called Patient self-inflicted lung injury (P-SILI). The effect of TV on the outcome of patients with de novo AHRF under HFNC has never been evaluated since TV is not easily accessible in patients under HFNC. Investigators hypothesized that a large TV during HFNC has an impact on the outcome. TV will be measured using chest Electrical Impedance Tomography (EIT). To calibrate the EIT data, i.e. to be able to convert changes in thoracic impedance into TV, thoracic impedance signal, flow and volume will be collected during a 4 cmH2O continuous positive airway pressure (CPAP) test, using a pneumotachograph inserted on the ventilator circuit between the mask and the Y-piece. Such a level of CPAP is supposed to reproduce the majority of the physiological effects of HFNC. Thus, EIT signal can be used to calculate TV during HFNC since it remains reliable even when the positive expiratory pressure changes.

A secondary objective is to quantify a respiratory distress index. This quantification will be recorded by respiratory inductance plethysmography (RIP), obtained using two elastic bands equipped with a sensor sensitive to their stretching, one positioned at the level of the thorax, the other at the level of the abdomen. The stretching changes of the two bands during the respiratory cycle allow evaluating their possible asynchronism by calculating the phase angle Investigators want to be able to evaluate up to 6 predictors of HFNC failure in this research with an effect size of 0.15, α risk of 0.05, and a power of 0.8. A number of 55 participants is required. Investigators plan to include 60 patients due to potential withdrawal of consent and/or unusable data.

Conditions

• Acute Hypoxemic Respiratory Failure

Interventions

DIAGNOSTIC_TEST

Assessment of tidal volume using Electrical Impedance Tomography (EIT) during high flow nasal canula(HFNC)

After information and consent, patients under HFNC for de novo acute hypoxemic respiratory failure will undergo a ten minutes 4cmH2O continuous positive airway pressure(CPAP) test while monitored with 1)chest Electrical Impedance Tomography (EIT) 2) a pneumotachograph inserted on the ventilator circuit between the mask and the Y-piece and connected to a differential pressure sensor, and 3) respiratory inductance plethysmography (RIP). Airway flow signal will be acquired using an analog/digital converter and stored for further analysis with acknowledge software. This will allow converting EIT data into tidal volume (TV), and estimating TV under HFNC. RIP signals will allow evaluating asynchronism between chest and abdomen by calculating the phase angle, thus quantifying respiratory distress. Patients monitored with an arterial catheter, arterial blood gas measurements will be done during CPAP and HFNC. These measures will be collected the first day of HFNC, and everyday up to three days

Sponsors & Collaborators

• Assistance Publique - Hôpitaux de Paris

  lead OTHER

Principal Investigators

• Guillaume CARTEAUX, Doctor · Assistance Publique Hôpitaux de Paris - CHU Henri Mondor - Créteil

Study Design

Allocation

NA

Purpose

DIAGNOSTIC

Masking

NONE

Model

SINGLE_GROUP

Eligibility

Min Age

18 Years

Sex

ALL

Healthy Volunteers

No

Timeline & Regulatory

Start

2019-06-01

Primary Completion

2021-06-03

Completion

2021-09-01

Countries

• France

Study Locations