From the Guidelines
The optimal position for a patient in acute respiratory distress is typically upright, with the head of the bed elevated at 30-45 degrees in a semi-Fowler's or high Fowler's position, as recommended by the most recent guidelines 1. This positioning helps maximize lung expansion, decreases the work of breathing, and improves oxygenation by reducing pressure on the diaphragm from abdominal contents. For patients who remain hypoxemic despite this positioning, prone positioning (lying face down) may be beneficial, especially in cases of moderate to severe ARDS, as it promotes better ventilation-perfusion matching by redistributing blood flow to better-ventilated lung regions, as supported by recent studies 1. Lateral positioning (lying on one side) with the affected lung upward may also help in unilateral lung disease. It's essential to reassess the patient frequently, monitoring oxygen saturation, respiratory rate, and work of breathing to determine if the positioning is effective. Positioning should be adjusted based on the patient's response and comfort level, and supplemental oxygen should be provided as needed, following the guidelines for oxygen use in adults in healthcare and emergency settings 1. These positioning strategies work by optimizing lung mechanics, reducing the work of breathing, and improving ventilation-perfusion matching, which ultimately enhances oxygen delivery to tissues. The BTS guideline for oxygen use in adults in healthcare and emergency settings recommends that fully conscious hypoxaemic patients should ideally be allowed to maintain the most upright posture possible, unless there are good reasons to immobilise the patient 1. Recent guidelines from the American Thoracic Society, European Society of Intensive Care Medicine, and Society of Critical Care Medicine also support the use of prone positioning for more than 12 hours a day in severe ARDS, as it has been shown to improve oxygenation and reduce mortality 1.
From the Research
Optimal Positioning for Patients in Acute Respiratory Distress
The optimal position for a patient in acute respiratory distress can vary depending on the specific condition and needs of the patient. However, several studies have investigated the effects of different positions on gas exchange, oxygenation, and other outcomes in patients with acute respiratory distress syndrome (ARDS).
- Upright Positioning: A study published in 2005 found that upright positioning of patients with ARDS resulted in a significant increase in the PaO2/FiO2 ratio, indicating improved gas exchange 2. This position, with the whole body in a straight line at 40 to 45 degrees, was well-tolerated by patients and did not cause significant hemodynamic changes.
- Prone Positioning: Prone positioning has been shown to improve outcomes in patients with severe ARDS. A randomized controlled trial published in 2013 found that prone positioning significantly decreased 28-day and 90-day mortality in patients with severe ARDS 3. This position may help to improve lung recruitment and reduce ventilation-perfusion mismatch.
- Positioning in Infants and Children: In hospitalized infants and children with acute respiratory distress, prone positioning has been found to be more beneficial than supine positioning in terms of oxygen saturation and partial pressure of arterial oxygen 4. However, the benefits of prone positioning must be weighed against the risk of sudden infant death syndrome (SIDS) in young infants.
- Seated Positions: A study published in 2013 evaluated the effects of different seated positions on lung volume and oxygenation in patients with ARDS. The results showed that verticalization, or sitting up, increased lung volume and improved oxygenation in approximately 32% of patients 5.
- Role of Positioning in Preventing Ventilator-Associated Pneumonia: Positioning can also play a role in preventing ventilator-associated pneumonia (VAP). The supine horizontal body position has been shown to increase the risk of pulmonary aspiration and VAP, while the semirecumbent position has been found to have benefits in preventing VAP 6. The prone position may also have beneficial effects in reducing the risk of VAP, although its use is limited by associated adverse effects.