Prone Ventilation

Prone Ventilation (Prone Positioning) 

The landmark:PROSEVA Trial(2013)

 Demonstrated significant mortality reduction in severe ARDS when:

• Used early
• Used for prolonged periods-at least 16 hours a day for 4-5 days on average (i.e. for ~ 70-75% of the time)
• Combined with lung-protective ventilation

Since then, prone positioning became standard care for severe ARDS.

Physiological Basis

Why Supine Position Is Harmful in ARDS?

In ARDS:

• Lungs become heavy due to:
• Edema
• Inflammation
• Atelectasis

In supine position: Dorsal (posterior) lung regions

Become compressed by:

• Heart—Mediastinum—Edematous lungs—Abdominal pressure

Result:

• Collapse of dependent alveoli
• Atelectasis
• Shunt formation

Ventral (anterior) regions

Remain relatively aerated and may become overdistended.Thus:

• Ventilation → Anterior lung
• Perfusion → Posterior lung
• Result:Severe V/Q mismatch

Physiological Effects of Prone Positioning

Indications

Strong Evidence-Based Indication-Moderate to Severe ARDS

PaO₂/FiO₂ <150 mmHg

Despite:

• Lung protective ventilation
• Adequate PEEP
• FiO₂ optimization

Common Practical Trigger

PaO₂/FiO₂ <150

with:

• FiO₂ ≥0.6
• PEEP ≥5 cmH₂O

Duration of Proning

• At least 16 hours/session
• Common:16–20 hours/day

Criteria for Discontinuation of Daily Proning

• When:PaO₂/FiO₂ >150–200 AND PEEP ≤10 AND FiO₂ ≤0.6 for at least four hours after the end of the last prone session.When Should Proning Be Started?
• Early initiation Within:24–48 hours of ARDS diagnosis Produces greatest mortality benefit.

Avoid waiting until:

• FiO₂ 100%
• Severe refractory hypoxemia

Contraindications

There are very few absolute contraindications to prone positioning. Modern guidelines (ATS/ESICM, Intensive Care Society, SCCM, WHO, and PROSEVA protocol) emphasize that most contraindications are relative, and the decision should be individualized based on the risk-benefit ratio.

Absolute contraindications

1. Unstable spinal injury
• Unstable cervical spine fracture
• Unstable thoracic or lumbar spinal injury
• Recent spinal fixation not cleared by the spine surgeon

Relative contraindications

Proning may still be performed if the expected benefit outweighs the risks.

Hemodynamic

• Refractory shock despite vasopressors
• Life-threatening arrhythmias
• Mechanical circulatory support with unstable cannulation

Airway

• Difficult or unsecured airway
• Fresh tracheostomy (<24–48 hours, depending on expertise)
• High risk of accidental extubation

Neurologic

• Uncontrolled intracranial hypertension
• External ventricular drain (can still be proned in experienced centers)
• Recent craniotomy
• Unstable skull fractures

Spine and orthopedic

• Stable spinal injury requiring special precautions
• Pelvic instability
• Unstable long-bone fractures

Abdominal

• Massive abdominal distension
• Abdominal compartment syndrome
• Recent major abdominal surgery (relative in most patients)

Cardiovascular

• Recent sternotomy with closed chest (relative)
• Large unstable aortic aneurysm (rare)

Respiratory

• Massive hemoptysis
• Bronchopleural fistula (relative)

Obstetric

• Late pregnancy (third trimester)
• Can still be safely proned using appropriate padding.

Obesity

• Morbid obesity (BMI >40–50 kg/m²)
• Requires experienced staff and specialized positioning.

Other

• Extensive anterior burns or wounds
• Facial trauma or recent facial surgery
• Uncontrolled raised intraocular pressure or recent ocular surgery
• Severe pressure ulcers on anterior body surfaces

Open chest (sternotomy left open)

Open mediastinum after cardiac surgery

Open abdomen

Temporary abdominal closure (damage-control laparotomy)

Evisceration or inability to protect abdominal contents

Preparation Before Proning

Family discussion: Although not legally required in many jurisdictions, it is good practice to inform the family/surrogate that prone positioning is planned, explain its purpose, expected duration, and potential complications (e.g., pressure injuries, accidental line/tube dislodgement, facial edema).

Staff Requirements for Safe Prone Positioning

• Minimum 5–6 trained healthcare personnel are recommended for manual proning (number depends on patient size, obesity, and number of devices).
• Airway operator (1): Usually an intensivist, anesthesiologist, or respiratory therapist; responsible for maintaining cervical alignment, securing the ET tube, and coordinating the turn.
• Trunk/limb operators (3–4): Positioned on either side of the patient to turn the torso and limbs en bloc while maintaining spinal alignment.
• Lines/devices operator (1): Manages vascular lines, chest drains, feeding tube, urinary catheter, ECMO/CRRT circuits (if present), and monitoring cables to prevent dislodgement.
• Team leader (usually the physician or experienced ICU nurse): Performs the pre-proning checklist, coordinates the maneuver, gives commands, and confirms patient stability after proning.
• Additional staff may be required for morbid obesity, ECMO, CRRT, multiple drains, or other complex devices.

Ventilator Management During Proning

• Continue:Lung Protective Ventilation
• Plateau Pressure—<30 cmH₂O
• Driving Pressure—<15 cmH₂O preferred
• Driving Pressure=Pplat −PEEP

Permissive Hypercapnia

Accept if pH acceptable.

Care During Proning

• ABG: Baseline before proning, repeat after 30–60 minutes, then every 4–6 hours (or earlier if clinical deterioration or ventilator changes).
• Airway: Confirm ET tube depth and cuff pressure after turning; perform frequent suctioning as needed (proning promotes secretion drainage).
• Sedation/analgesia: Ensure adequate analgesia and sedation; use neuromuscular blockade only when indicated(e.g., severe ventilator dyssynchrony or refractory hypoxemia).
• Positioning: Maintain 10–15° reverse Trendelenburg (head-up tilt) to reduce facial edema, aspiration risk, and intraocular pressure.
• Pressure injury prevention: Reposition head, arms (“swimmer’s position”), and legs every 2 hours; keep elbows flexed to approximately 90° and protect all pressure points with padding.
• Eye care: Keep eyelids closed/taped, lubricate eyes, and avoid direct ocular pressure.
• Oral care: Perform regular oral hygiene and suction oral secretions to reduce aspiration risk and skin maceration.
• Nutrition: Confirm nasogastric/orogastric tube position before feeding; continue enteral nutrition if tolerated and monitor gastric residuals per ICU protocol.
• Lines and drains: Regularly check all vascular lines, chest drains, urinary catheter, and monitoring cables for secure position and kinking.
• Hemodynamic monitoring: Continuously monitor BP, ECG, SpO₂, and urine output; reassess after every position change.
• Skin assessment: Inspect the face, chest, pelvis, knees, and genitalia for pressure injury at each repositioning.

Complications

Proning and Enteral Nutrition

Current ICU practice:

• Gastric feeding can continue
• Head elevated 10–25°
• Monitor residuals

Routine cessation not required.

Proning and ECMO

Proning remains beneficial even during:

VV-ECMO

Potential benefits:

• Better recruitment
• Improved oxygenation
• Reduced VILI

Increasingly used in expert centers.

Awake Proning

Prone positioning without intubation.

Commonly used in:

• Hypoxemic respiratory failure
• Viral pneumonia

Including:COVID-19

Benefits:

• Improved oxygenation
• May reduce intubation rate

Mortality benefit less certain.

References

• Lakshmikanthcharan S, et. al: Prone ventilation in ARDS
• Guérin C, Albert RK, Beitler J, Gattinoni L, Jaber S, Marini JJ, Munshi L, Papazian L, Pesenti A, Vieillard-Baron A, Mancebo J. Prone position in ARDS patients: why, when, how and for whom. Intensive Care Med. 2020 Dec;46(12):2385-2396. doi: 10.1007/s00134-020-06306-w. Epub 2020 Nov 10. PMID: 33169218; PMCID: PMC7652705.