Study to Measure the Prevalence of Asynchrony In Mechanically Ventilated Patients

Prevalence of Patient Ventilator Asynchrony in Trauma and Surgical Patients

This study will examine the prevalence of patient-ventilator asynchrony and its determinants. Mechanically ventilated trauma patients often experience asynchrony when their pattern of breathing does not match the triggering of a mechanical ventilator.

Asynchrony is thought to be more common in delirious patients, patients with chronic lung disease and those who are heavily sedated. The study will examine the relationship between (1) delirium and sedation and (2) the prevalence of asynchrony in trauma patients.

This is a prospective observational study to determine the prevalence of patient/ventilator asynchrony in a cohort of trauma and surgical patients. There will be two 20-minute periods of observation. The first will be during the first 24 hours of mechanical ventilation and the second will take place when the patient is being weaned from the ventilator and is triggering half or more of all ventilator breaths.

The study team will use computer-captured waveforms to determine the proportion of all breaths that are asynchronous. This proportion is the primary outcome variable of the study.

The study hypothesis is that the proportion of asynchronous breaths is higher in patients with higher levels of sedation, as measured by the Richmond Agitation-Sedation Scale (RASS) and the Confusion Assessment Methods for the Intensive Care Unit (CAM-ICU). This hypothesis will be tested using repeated measures analysis of variance.

Inclusion Criteria:

• Trauma or surgical diagnosis
• Patients requiring mechanical ventilation

Exclusion Criteria:

• Patients with no spontaneous breathing efforts due to injury or chemical paralysis
• Patients with leaks in the patient ventilator system precluding evaluation of waveforms