Lungs surrounded by a protective barrier, symbolizing lung protection during breathing.

Breathing Easy: How to Protect Your Lungs During Spontaneous Breathing

Lena Voss in Health & Wellness December 2025 • 4 min read.

"Understanding and mitigating ventilator-induced lung injury (VILI) and patient self-inflicted lung injury (P-SILI) for better respiratory health."

In the early 2000s, medical professionals became increasingly aware of ventilator-induced lung injury (VILI) when using mechanical ventilation to support patients with acute respiratory failure. This heightened awareness stemmed from a significant randomized controlled trial by the ARDS Network, highlighting the importance of understanding and preventing VILI.

VILI is associated with the excessive stretch of alveoli in the lungs. To minimize VILI during passive ventilation, doctors often use a strategy called lung-protective ventilation, which involves limiting tidal volume to 6 mL/kg of ideal body weight and maintaining plateau pressure below 28-30 cmH2O. While effective, this method is primarily designed for patients under passive ventilation, raising questions about its effectiveness during spontaneous breathing.

The question arises: can spontaneous breathing itself cause lung injury? Research suggests the answer is yes, leading to the concept of patient self-inflicted lung injury (P-SILI). Two studies in 1988 demonstrated that both negative pressure ventilation in animals and spontaneous hyperventilation in sheep could lead to lung injury similar to VILI. Understanding how to minimize P-SILI is crucial for optimizing respiratory care.

How to Minimize P-SILI: Balancing Assistance and Protection

Lungs surrounded by a protective barrier, symbolizing lung protection during breathing.

Minimizing P-SILI involves two main strategies. The first is complete elimination of spontaneous effort through full ventilatory support. While effective, this can lead to disuse atrophy of the respiratory muscles. Therefore, the second strategy involves using positive ventilation to support the patient's spontaneous effort, known as assisted ventilation. Optimizing this approach requires a reliable way to assess lung overstretch at the bedside.

Ideally, lung strain (the deformation of lung tissue relative to its original size) is the best measure of overstretch, but it's challenging to assess in practice. Alternatively, lung stress, or the force experienced by the lungs, can serve as a surrogate. Lung stress is typically measured by transpulmonary pressure, the difference between airway and pleural pressure. Pleural pressure is often estimated using an esophageal catheter, but this method isn't widely implemented.

Eliminate Spontaneous Effort: Complete ventilatory support to rest the respiratory muscles.
Support Spontaneous Effort (Assisted Ventilation): Balance positive ventilation with the patient's breathing.
Monitor Lung Overstretch: Assess lung strain or stress to prevent excessive deformation.

Clinicians often use airway pressure as a substitute for transpulmonary pressure, but this can be inaccurate during spontaneous breathing because it doesn't account for the force exerted by respiratory muscles. During spontaneous breathing, direct measurement of airway plateau and driving pressures requires temporarily relaxing the respiratory muscles, which isn't always feasible. Instead, if lung compliance remains stable, limiting tidal volume can effectively control tidal stress during both passive and spontaneous breathing.

The Path Forward: Preserving Spontaneous Effort While Protecting Lungs

The journey to optimizing ventilator settings and modes to reduce P-SILI remains ongoing. From a physiological perspective, developing a ventilatory strategy that minimizes P-SILI while preserving spontaneous effort is a continuous and essential pursuit. Future research and clinical trials are needed to refine our understanding and improve patient outcomes.

About this Article -

This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

Everything You Need To Know

What is ventilator-induced lung injury (VILI), and how does it differ from patient self-inflicted lung injury (P-SILI)?

Ventilator-induced lung injury (VILI) is damage to the lungs caused by mechanical ventilation, specifically excessive stretching of the alveoli due to factors like high tidal volumes. This was recognized in the early 2000s, after the ARDS Network study. Patient self-inflicted lung injury (P-SILI), on the other hand, is lung damage caused by the patient's own spontaneous breathing efforts. Research has shown that spontaneous hyperventilation can lead to lung injury. Both VILI and P-SILI share similar mechanisms of lung damage, though their origins differ; one is from the ventilator, the other from the patient's breathing pattern.

How can lung-protective ventilation help, and is it effective during spontaneous breathing?

Lung-protective ventilation, a strategy used to prevent ventilator-induced lung injury (VILI), involves limiting tidal volume to 6 mL/kg of ideal body weight and keeping plateau pressure below 28-30 cmH2O. This method is primarily designed for patients under passive ventilation. However, the application and effectiveness of lung-protective ventilation during spontaneous breathing are more complex, as the patient is actively breathing, and additional measures may be needed to prevent patient self-inflicted lung injury (P-SILI).

What strategies are used to minimize patient self-inflicted lung injury (P-SILI), and how do they work?

Minimizing patient self-inflicted lung injury (P-SILI) involves two primary strategies. The first strategy is to eliminate spontaneous effort by providing complete ventilatory support, which effectively rests the respiratory muscles, but risks causing disuse atrophy. The second strategy involves assisted ventilation, where positive ventilation supports the patient's own breathing efforts. This approach requires a balance to prevent lung overstretch, often monitored by assessing lung strain or, indirectly, lung stress, typically measured using transpulmonary pressure.

Why is monitoring lung overstretch crucial in respiratory care, and what methods are used to assess it?

Monitoring lung overstretch is essential to prevent both ventilator-induced lung injury (VILI) and patient self-inflicted lung injury (P-SILI). Excessive lung strain can damage the delicate structures of the alveoli. Ideally, lung strain is the best measure of overstretch, but practically challenging to assess. Alternatively, lung stress, or the force experienced by the lungs, can be used as a surrogate and is measured using transpulmonary pressure, which is the difference between airway and pleural pressure. While direct measurement of transpulmonary pressure is not always feasible, clinicians may use tidal volume to manage the tidal stress when lung compliance is stable, effectively controlling lung overstretch during both passive and spontaneous breathing.

What are the challenges and future directions in optimizing respiratory care to prevent lung injury?

Optimizing ventilator settings and modes to reduce patient self-inflicted lung injury (P-SILI) is an ongoing process. Current challenges involve balancing the need to support the patient's breathing with the need to protect the lungs. This includes the difficulty of accurately assessing lung overstretch, which could lead to ventilator-induced lung injury (VILI). Future directions include developing ventilatory strategies that minimize P-SILI while preserving spontaneous effort and conducting further research to improve patient outcomes. Clinicians are continually working to refine methods and improve the balance of supporting the patient's breathing while ensuring lung protection.