Voices of Patients' Relatives to Support Weaning From Mechanical Ventilation

Methods: Adult ICU-patients with controlled mechanical ventilation ≥48h due to a neurological disease will be included in the intensive care unit. A predefined text - including information on the patient's condition and recurrent request to breath in and out - will be recorded as an audio file by one of the patient's relatives. Patients will be randomly assigned in a 1:1 ratio to the conventional treatment arm or the Voice-Weaning arm. In the conventional arm, audio recordings will be muted by an independent person resulting in a mute recording without audio signals.

When conversion from controlled to assisted mechanical ventilation is intended according to standard treatment, audio recordings will be administered in repeat mode for 10 minutes and performed three times per day. If spontaneous breathing trials (SBT) are intended according to standard treatment, the audio recordings will be played during the SBT three times per day.

Criteria for weaning not to be intended - according to Boles et al. (Weaning from mechanical ventilation. Eur Respir J. 2007) and adapted to neurological patients:

Objective measurements:

• Unstable clinical condition

• Cardiovascular status (fC≥140/min, systolic BP <90mmHg or >180mmHg, more than minimal vasopressors)
• Metabolic status (e.g. inacceptable electrolytes)
• Inadequate oxygenation

• SaO2 ≤90% on FiO2 >40% or pO2/FiO2 <150mmHg or pO2/FiO2 <120mmHg in case of chronic hypoxemia (Horowitz index)
• PEEP>8cmH2O
• Inadequate pulmonary function

• fR ≥35/min
• MIP>(-20 -) -25cmH2O
• VT ≤5ml/kgKG
• VC ≤10ml/kgKG
• fR/VT ≥105 breaths/min x l (RSBI)
• significant respiratory acidosis (pH≤7.25)
• Unstable neurological condition

• sedation or inadequate mentation on sedation
• present or anticipated intracranial mass effect (e.g. midline shift >10mm or progression, basal cistern effacement or oculomotor disturbance, signs of transfalxial/transtentorial/transforaminal herniation
• elevation of intracranial pressure (>20 cmH2O) and/or obstructive hydrocephalus
• severe vasospasms (>6 kHz in transcranial Doppler, or determined by CT-A/CT-P)
• status epilepticus (determined by EEG)
• acute intracranial infection (without established and/or treated origin)

Clinical assessment:

• Inadequate cough
• Excessive tracheobronchial secretion
• Disease acute phase for which the patient was intubated

Ethics Approval: The Institutional Review Board of the Friedrich-Alexander-Universität Erlangen-Nürnberg approved of the study on 13 November 2018.

Sample Size Calculation: The sample size is computed with 80% power and a 5% α-risk for the hypothesis of Voice Weaning achieving a 15% absolute weaning failure reduction. The sample size is increased by 10% to correct for dropouts and lost to follow up: a maximum of 354 patients will be included and an interim analysis be performed after inclusion of 50% of the calculated subjects.

Inclusion criteria

• Intubation and controlled mechanical ventilation ≥48h due to a neurological disease
• Weaning from mechanical ventilation intended by the attending physician
• Obtained informed consent from the legal representative

Exclusion criteria

• Age < 18 years
• History of psychiatric disease
• Weaning from mechanical ventilation not intended or decision to limit therapeutic interventions