Proning is a medical technique that involves carefully turning a patient from lying on their back (supine position) to lying face-down on their stomach (prone position). This repositioning is used primarily to improve oxygenation in individuals experiencing severe respiratory failure, most commonly those with Acute Respiratory Distress Syndrome (ARDS). Although the technique has been used for decades, it gained wider public attention for its application in treating patients with respiratory complications from illnesses like COVID-19. The change in body position helps the lungs function more effectively by redistributing pressure and optimizing gas exchange.
How Prone Positioning Improves Lung Function
The body’s anatomy creates a disadvantage to breathing when a person is lying on their back. In the supine position, the heart and abdominal contents press down on the lung tissue closest to the back, leading to the collapse of small air sacs (alveoli) in the dorsal lung regions. This compression creates a mismatch between ventilation (airflow) and perfusion (blood flow), because gravity pulls blood toward these collapsed, poorly ventilated areas. The result is blood passing through the lungs without picking up sufficient oxygen, known as a shunt.
Flipping the patient to the prone position reverses this effect of gravity. The weight of the heart and abdominal organs shifts to rest against the sternum and chest wall instead of compressing the lungs. This movement allows the dorsal lung regions, which contain the largest volume of lung tissue, to re-expand and become better ventilated. This re-opening of previously collapsed alveoli, known as lung recruitment, is a benefit of proning.
The prone position leads to a more uniform distribution of both ventilation and perfusion throughout the lung. While blood flow remains largely directed toward the dorsal areas due to gravity, these areas are now also better ventilated. This improved matching of ventilation to perfusion (V/Q matching) is the physiological reason for the increase in blood oxygen levels. The more homogeneous distribution of air and blood flow also helps reduce mechanical stress on the lungs, protecting them from further injury.
Clinical Use in Mechanically Ventilated Patients
Prone positioning is a well-established intervention in the Intensive Care Unit (ICU), particularly for patients with severe Acute Respiratory Distress Syndrome (ARDS) who require mechanical ventilation. The goal of proning in this setting is to improve oxygen saturation and reduce mortality. For patients with severe ARDS, defined by a very low ratio of arterial oxygen pressure to fraction of inspired oxygen (PaO2/FiO2), proning offers a survival advantage.
The procedure is complex and requires a coordinated team of specialists, typically including physicians, nurses, and respiratory therapists. The patient is secured with padding placed under the face, chest, and pelvis to prevent pressure sores and ensure the abdomen hangs freely, which prevents increased abdominal pressure from inhibiting lung function. The process must be performed carefully to avoid accidental removal of tubes, lines, or drains, such as the endotracheal tube connected to the ventilator.
Patients on mechanical ventilation are typically kept in the prone position for an extended duration, often between 12 to 16 hours per day. This extended period maximizes the therapeutic effect and is repeated over several days until the patient’s oxygenation stabilizes. The decision to stop proning is made when the patient maintains adequate oxygen levels while briefly positioned on their back.
Guidance for Self-Proning at Home
Self-proning is a modification of the technique for conscious, non-intubated individuals with mild to moderate respiratory issues. The purpose is to use the same physiological benefits to improve oxygenation and potentially prevent the condition from worsening to the point of needing mechanical ventilation. This practice is a supportive measure and should only be undertaken after consulting a healthcare provider.
For self-proning, the approach involves rotating through several positions rather than remaining face-down constantly. A common rotation includes lying on the stomach for 30 minutes to two hours, then switching to the right side, sitting upright, and then lying on the left side before returning to the prone position. Pillows should be used to support the head, chest, and pelvis to ensure comfort and prevent pressure on the knees or abdomen.
Avoid self-proning immediately after eating to reduce the risk of reflux. The person should return to a comfortable position immediately if they experience increased pain, discomfort, or shortness of breath. Monitoring oxygen saturation with a pulse oximeter 15 minutes after each position change helps ensure the repositioning is beneficial.
When Prone Positioning Should Be Avoided
Prone positioning is not suitable for every patient and has specific safety restrictions, known as contraindications. Absolute contraindications include conditions that would be immediately worsened or made life-threatening by the position change. These include unstable spinal fractures, severe facial trauma, or significantly increased pressure within the skull.
Other conditions are considered relative contraindications, meaning the risk must be weighed against the potential benefit. These include severe hemodynamic instability, recent major abdominal or thoracic surgery, or open wounds on the front of the body. Women in the second or third trimester of pregnancy are advised to avoid proning due to discomfort and pressure on the fetus. In the hospital setting, a risk is the dislodgement of various tubes and lines during the turning process, which requires specialized personnel to manage.