The levels of recommendation (1-3) and classes of evidence (I-III) are defined at the end of the "Major Recommendations" field.
Level 1
There is no mortality difference between patients receiving early tracheostomy (3 to 7 days) and late tracheostomy or extended endotracheal intubation.
Level 2
Early tracheostomy decreases the total days of mechanical ventilation and intensive care unit length of stay (ICU LOS) in patients with head injuries. Therefore, it is recommended that patients with a severe head injury receive an early tracheostomy.
Level 3
Early tracheostomy may decrease the total days of mechanical ventilation and ICU LOS in trauma patients without head injuries. Early tracheostomy may decrease the rate of pneumonia in trauma patients. Therefore, it is recommended that early tracheostomy be considered in all trauma patients anticipated to require mechanical ventilation for > 7 days.
Definitions:
Rating Scheme for Strength of Recommendations
Level 1
The recommendation is convincingly justifiable based on the available scientific information alone. This recommendation is usually based on Class I data, however, strong Class II evidence may form the basis for a Level I recommendation, especially if the issue does not lend itself to testing in a randomized format. Conversely, low quality or contradictory Class I data may not be able to support a Level I recommendation.
Level 2
The recommendation is reasonably justifiable by available scientific evidence and strongly supported by expert opinion. This recommendation is usually supported by Class II data or a preponderance of Class III evidence.
Level 3
The recommendation is supported by available data but adequate scientific evidence is lacking. This recommendation is generally supported by Class III data. This type of recommendation is useful for educational purposes and in guiding future clinical research.
Rating Scheme for Strength of Evidence
Class I
Prospective randomized controlled trials
Class II
Clinical studies in which data was collected prospectively and retrospective analyses that were based on clearly reliable data. Types of studies so classified include observational studies, cohort studies, prevalence studies and case control studies.
Class III
Studies based on retrospectively collected data. Evidence used in this class includes clinical series and database or registry review.