Is Prone Positioning the Best Choice for ARDS Patients?

Acute respiratory distress syndrome (ARDS) is a life-threatening lung injury that allows fluid to enter the lungs, making breathing difficult and affecting how much oxygen can enter the body. To help those with ARDS, prone positioning is often recommended, although it is crucial to first weigh its potential benefits with its possible adverse events.

In this article, we’ll take a look at those benefits and potential complications of the practice, as well as when prone positioning should be employed or avoided.

What Is Prone Positioning?

Prone positioning is the medical term for lying face-down on the stomach, and is a position often used with patients who have moderate to severe respiratory illness. This is in comparison to supine positioning, the standard position for hospitalized patients, which is when the patient lies on their back.

When Should Prone Positioning Be Used?

There are two main indications for implementing prone positioning in patients with ARDS: a need to improve oxygenation or as a potential therapy to help reduce mortality.

The greatest contraindication for prone positioning is in cases where the patient has an unstable spinal fracture.¹ 

Other relative contraindications that may be considered for prone positioning on a case-by-case basis include:

• unstable long bone or pelvic fracture
• open abdominal wounds
• hemodynamic instability
• increased intracranial pressure from head and neck positioning partially blocking cerebral venous drainage

As for all other patients, meta-analyses of randomized controlled trials suggest that prone positioning only offers a survival advantage to patients with relatively severe ARDS. Additionally, research suggests that those with severe ARDS may benefit from combining adjunctive therapies such as recruitment maneuvers, high PEEP, and inhaled vasodilators with prone positioning because of their additive effect on improving oxygenation.²

Further research in support of prone positioning in ARDS patients has shown that early application of prolonged prone positioning (16+ hours) significantly decreased 28-day and 90-day mortality.^{3, 4}

However, these results still do not confirm the ability of prone positioning to improve patient outcomes, as an alternative study concluded that there is no significant survival benefit from prone positioning in patients with ARDS.⁵

These mixed research results are why prone positioning currently remains a case-by-case decision, where doctors must weigh the potential benefits with possible adverse events. 

Benefits Offered by Prone Positioning

Prone positioning can offer many benefits for patients with ARDS.

Less Lung Compression

One of the greatest benefits of prone positioning for those with ARDS is connected to the changes it causes in the compression of the body. With supine positioning, the heart and abdominal organs compress the lungs, reducing gas exchange and leading to low oxygen levels. Since ARDS already lowers oxygen levels, supine positioning can lower them even further. In comparison, prone positioning does not compress the lungs as much, allowing for better gas exchange and oxygen levels.⁶

Redistribution of Blood and Air Flow

ARDS causes an imbalance between blood and airflow. However, body positioning can alter the mechanisms that balance blood flow, and with prone positioning, blood and airflow are distributed throughout the body more evenly, improving gas exchange.²

Decreased Ventilator Reliance

Prone positioning is often used for those with ARDS who require mechanical ventilation. However, since prone positioning can help improve lung function, the patient may require less support from the ventilator. With ventilator-induced lung injury (VILI) as a potential complication of mechanical ventilation, the ability of prone positioning to reduce ventilator reliance may also reduce the risk of ventilator-induced lung injury.⁶

Adverse Events with Prone Positioning

While prone positioning can offer many benefits for individuals with ARDS, it is also essential to acknowledge the adverse events that may cause some patient conditions to worsen or remain the same.

With the change in position from supine to prone, it is possible for breathing tubes, medical devices, and drains to dislodge. The breathing tube, in particular, is challenging to replace should it become dislodged while the patient is in a prone position.⁶

The prone position also makes it difficult to perform lifesaving procedures, such as cardiopulmonary resuscitation (CPR), and often requires immediate repositioning.

A review⁷ of 41 studies found adverse events from prone positioning that include:

• severe desaturation
• barotrauma
• pressure sores
• ventilation-associated pneumonia
• facial edema
• arrhythmia
• hypotension
• peripheral nerve injury

Because of these adverse events, it is crucial to consider prone positioning for those with ARDS on an individual basis.

Final Remarks

Prone positioning is becoming more popular in the treatment of ARDS patients because of its ability to increase oxygenation and alveolar recruitment while decreasing mortality. However, some adverse events can occur with prone positioning, and the research surrounding its benefits for ARDS patients is split.

In the end, the use of prone positioning in patients with ARDS should be considered on a case by case basis and the severity of the illness.

References

1. Guérin, C., Albert, R. K., Beitler, J., Gattinoni, L., Jaber, S., Marini, J. J., Munshi, L., Papazian, L., Pesenti, A., Vieillard-Baron, A., & Mancebo, J. (2020). Prone position in ARDS patients: why, when, how and for whom. Intensive care medicine, 46(12), 2385–2396. https://doi.org/10.1007/s00134-020-06306-w
2. Kallet R. H. (2015). A Comprehensive Review of Prone Position in ARDS. Respiratory care, 60(11), 1660–1687. https://doi.org/10.4187/respcare.04271
3. Guérin, C., Reignier, J., Richard, J. C., Beuret, P., Gacouin, A., Boulain, T., Mercier, E., Badet, M., Mercat, A., Baudin, O., Clavel, M., Chatellier, D., Jaber, S., Rosselli, S., Mancebo, J., Sirodot, M., Hilbert, G., Bengler, C., Richecoeur, J., Gainnier, M., … PROSEVA Study Group (2013). Prone positioning in severe acute respiratory distress syndrome. The New England journal of medicine, 368(23), 2159–2168. https://doi.org/10.1056/NEJMoa1214103
4. Tekwani, S. S., & Murugan, R. (2014). 'To prone or not to prone' in severe ARDS: questions answered, but others remain. Critical care (London, England), 18(3), 305. https://doi.org/10.1186/cc13893
5. Taccone, P., Pesenti, A., Latini, R., Polli, F., Vagginelli, F., Mietto, C., Caspani, L., Raimondi, F., Bordone, G., Iapichino, G., Mancebo, J., Guérin, C., Ayzac, L., Blanch, L., Fumagalli, R., Tognoni, G., Gattinoni, L., & Prone-Supine II Study Group (2009). Prone positioning in patients with moderate and severe acute respiratory distress syndrome: a randomized controlled trial. JAMA, 302(18), 1977–1984. https://doi.org/10.1001/jama.2009.1614
6. Hadaya, J., & Benharash, P. (2020). Prone Positioning for Acute Respiratory Distress Syndrome (ARDS). JAMA, 324(13), 1361. doi: 10.1001/jama.2020.14901 
7. González-Seguel, F., Pinto-Concha, J., Aranis, N., & Leppe, J. (2021). Adverse Events of Prone Positioning in Mechanically Ventilated Adults With ARDS. Respiratory Care, 66(12), 1898-1911. doi: 10.4187/respcare.09194

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