Ventilator-associated pneumonia (VAP) is the most common hospital-acquired infection in the intensive care unit (ICU).[1] It occurs in 9% to 40% of all ICU patients and has an incidence of 5 to 35 cases per 1000 ventilator days.[2] The consequences of VAP are severe: a three-fold increased duration of mechanical ventilation, a two- to six-fold increase in ICU stay, a 2- to 3-day increase in hospital stay.[3]Each case of VAP increases US hospital costs by $40,000 to $50,000 and results in a 15% to 45% increase in attributable mortality.[2,4]

Elevation of the head-of-bed (HOB) of intubated patients is an effective method for reducing rates of aspiration pneumonia. In a randomized two-period crossover study, Torres et al.[5] demonstrated that the semirecumbent position decreased rates of aspiration of gastric contents four-fold. Kollef[6] used multivariate analysis for risk factors of developing aspiration pneumonia and found that head position <30 degrees in the first 24 hrs of intubation was an independent risk factor for developing VAP. The other risk factors were organ system failure, age >60 yrs, and previous antibiotic use. Thus, at the time of intubation, the only modifiable risk factor for the development of aspiration pneumonia risk was head position. In a landmark study, Druculovic et al.[7] performed a randomized trial assessing the frequency of clinically suspected and microbiologically confirmed nosocomial pneumonia in semirecumbent vs. supine position in 86 intubated patients. Thirty-four percent of patients in the supine position developed VAP compared with only 8% of patients in the semirecumbent group. Supine body position (odds ratio 6.8) and enteral nutrition (odds ratio, 5.7) were independent risk factors for nosocomial pneumonia. Those patients in the supine position and receiving enteral nutrition had the highest frequency of VAP (50%). Mechanical ventilation for ≥7 days and a Glasgow Coma Scale score <9 were additional risk factors.

Again, the only modifiable risk factor for the development of VAP was elevation of HOB.

Because of the importance of adequate HOB elevation in preventing VAP, the 1997 Centers for Disease Control and Prevention (CDC) Guidelines for Preventing Aspiration Pneumonia and the 2003 CDC and the Healthcare Infection Control Practices Advisory Committee recommend elevating the HOB of a patient at high risk for aspiration at an angle of 30-45 degrees unless this is contraindicated.[4] The Institute for Healthcare Improvement Safer Systems Saving Lives Campaign has made HOB elevation one of four components of the Ventilator Bundle for preventing nosocomial infections.[8] Most recently, the 2006 Society for Critical Care Medicine Outcomes Task Force endorsed HOB elevation as a method to reduce aspiration pneumonia.[9]

While it is not immediately clear whether elevation of the HOB aids in the prevention of ventilator-associated pneumonia by decreasing the risk of aspiration of gastrointestinal contents or oropharyngeal and nasopharyngeal secretions, this was the ostensible reason for the initial recommendation.

Another reason that the intervention was suggested was to improve patients’ ventilation. Patients in the supine position will have lower spontaneous tidal volumes on pressure support ventilation than those seated in an upright position. Although patients may be on mandatory modes of ventilation, the improvement in position may aid ventilatory efforts and minimize atelectasis.

Furthermore, Elevation of the HOB to 30-Degrees has been shown to be of benefit in lowering intracranial pressure (ICP) (Level 2 Recommendation).

Elevating the HOB is thought to promote intracranial venous return and increase CSF drainage from the head, resulting in decreased ICP (Fan, 2004) Four controlled studies with sample sizes ranging from 5 to 38 patients with severe TBI found significant decreases in ICP with HOB elevations of 30 degrees (Moraine, Berré, & Mélot, 2000; Ng, Lim, & Wong, 2004; Schulz-Stubner & Thiex, 2006; Winkleman, 2000). Increases to 45 degrees caused ICP to rise from the level found
at 30 degrees in one study (Moraine et al.). A systematic review of 11 studies found that 9 studies demonstrated significantly decreased ICP at elevations of 30 degrees (Fan). All 9 studies included patients with severe TBI, with sample sizes ranging from 11 to 25. The effect size (to determine how effectively HOB elevation decreases ICP) was calculated to be moderate-to-large in the 5 studies for which such data were available.

All patients in the critical care setting, not just ventilated patients or those with elevated ICP, should derive benefit from the 30-Degree Elevated HOB Position.  Arguably, this patient positioning should be recommended for all ICU patients, unless contraindicated.  It is a simple intervention that produces dramatic benefit in regards to patient care and patient outcomes.

(Please refer to attached references for full footnote citation)

References:

1. Institute for Health Care Improvement (IHI) How to Guide: Prevent Ventilator Associated Pneumonia (VAP)

2. American Association of Neuroscience (AANN) Clinical Practice Guideline: Nursing Management of Adults with Severe Traumatic Brain Injury

3. The Barrow Neurological Institute: Patient Positioning: More Than Just “Turn Every 2h”

4. Guidelines: Head of Bed Elevation in the ICU (surgicalcriticalcare.net)