Effects of Nasal Ventilation on Cerebral and Pulmonary Function in Orally Intubated Patients

Assistance Publique - Hôpitaux de Paris22 enrolled

Overview

The passage of air through the nasal cavity generates rhythmic oscillations transmitted by the olfactory bulb to the brain, which induces cerebral activation in functional areas and is associated with better cognitive performance compared to oral breathing. Consequently, the abolition of nasal ventilation in patients intubated via the orotracheal route could have deleterious effects on brain activity. Besides the loss of olfaction, the abolition of nasal ventilation could affect brain activity and respiratory control, consequently altering regional pulmonary ventilation. The hypothesis of the study is that nasal ventilation through the passage of humidified nasal airflow in patients intubated via the orotracheal route would be associated with modulation of cerebral electrical activity and tissue oxygenation and a modification of regional pulmonary ventilation.

The effects of nasal ventilation on cerebral activity will be studied on orally intubated and sedated patients in six experimental conditions. The first condition consists of nociceptive stimulation of the left upper limb as a negative control. In three conditions, the inspired fraction of oxygen (FiO2) will remain at 21% while applying three different rates of humidified nasal air at 0L/min, 30L/min and 60L/min respectively. The last two conditions consist of applying humidified nasal air at 30L/min and 60L/min with a FiO2 of 100%. The primary objective of this study is to evaluate the effects of high-flow humidified nasal air on electroencephalogram activity (root mean square gamma frequency) in sedated, orally intubated patients. The secondary objectives of the study are to evaluate the effects of high-flow humidified nasal air on cerebral perfusion and oxygenation, gas exchange and regional pulmonary ventilation in the same patients.

Study Type

OBSERVATIONAL

Enrollment

Conditions

Hypoxemic Acute Respiratory Failure

EEG activity measurementDEVICE

The nasal ventilation device (placed as part of the research) (AIRVO 2; Fisher and Paykel Healthcare, Auckland, New Zealand) will be positioned via nasal cannulas adapted to the patient's anatomy. The FiO2 will be set at 21% and the flow rate will be fixed at 0 L/min at the inclusion visit. The temperature of the humidified nasal oxygenator will be set at 31°C. Six 30-minute experimental conditions will be performed successively: 1) 0 L/min flow, FiO2 21%, 2) 30 L/min flow, FiO2 21%, 3) 30 L/min flow, FiO2 100%, 4) 60 L/min flow, FiO2 21%, 5) 60 L/min flow, FiO2 100%, 6) Negative control. At the end of each condition, a 10-minute thoracic electrical impedance tomography recording, a 10-minute EEG recording, a 10-minute cerebral NIRS recording and an instantaneous temporal Doppler velocity measurement will be performed. A blood gas (1.5 mL) will also be taken at the end of each condition.

Eligibility

Sex: ALLMin age: 18 Years

Medical Language ↔ Plain English

Inclusion Criteria: 1. Age ≥ 18 years old 2. Hypoxemic acute respiratory failure 3. Intubation and mechanical ventilation since less than 4 days 4. PaO2/FiO2 ratio less than 200 5. RASS\<-4 6. Consent obtained from next of kin 7. Patient with health insurance Exclusion Criteria: 1. Central nervous system diseases (stroke, MS, epilepsy) 2. Psychiatric illnesses (psychosis, depression) (indicated on patient's medical record) 3. Hemodynamic instability (noradrenalin\>2mg/h) 4. Patient on AME 5. Patients under legal protection (guardianship/curators) 6. Pregnant or breast-feeding women

Outcomes

Primary Outcomes

Study the effects of nasal ventilation on brain electrical activity using electroencephalogram recording (EEG) in sedated orotracheally intubated patients.

EEG spectral density spectrum of gamma frequency.