Weaning And Variability Evaluation (WAVE)

In this prospective observational pilot study, mechanically ventilated patients weaning or near extubation (i.e. within 1-5 days) were selected to undergo continuous heart rate (EKG waveform at 500 Hz) and respiratory rate (expired CO2 waveform at 100 Hz) recording. The data was collected as per standard practice by the bedside monitor (Phillips Intelivue MP70). A portable CPU with TrendfaceTM software was used to download the data for variability analysis. All decisions on timing of SBTs and extubation were left to the discretion of the treating team who were unaware of the variability results. SBT's were repeated daily from trial onset until extubation patient permitting.

Inclusion criteria

• Patients who have been requiring mechanical ventilation for >48 hours.
• At least partial reversal of the condition precipitating invasive ventilation.
• Stabilization of "other" organ system failures (i.e. no worsening).
• The patient is able to tolerate pressure support ventilation ≤14 cm H2O (SpO2 ≥ 90% with FiO2 ≤ 40% and PEEP ≤ 10 cm H2O)
• The patient is hemodynamically stable (off vasopressors or on low levels of vasopressors).
• Stable neurological status (no deterioration in the last 24 hors, intact respiratory drive and ICP < 20).
• The patient has intact airway reflexes (adequate cough with suctioning and a gag reflex).

Exclusion criteria

• Allergy to skin adhesives or a contraindication to placing electrocardiogram adhesives (e.g. severe psoriasis).
• Do not reintubate order documented on chart or anticipated withdrawal of life support.
• Tracheostomy
• Known or suspected severe myopathy or neuropathy (i.e. myasthenia gravis, Guillain-Barré syndrome) or quadriplegia.
• Severe heart failure or Grade IV left ventricular function.
• Prior extubation during ICU stay.