Assessing the Role of Mechanical Ventilation in Diaphragm Dysfunction Associated with Critical Illness: Longitudinal Patterns Alone Do Not Confirm Causality

By
Xibin Feng
Miao Yang
Wei Xu
September 5, 2026

Critical Care

Objective:

To challenge the assertion that mechanical ventilation is the primary cause of diaphragm weakness in critically ill patients and to clarify the roles of critical illness and ventilatory management.

Approach:

Causal Analysis: The article critiques the causal claims made regarding diaphragm dysfunction and mechanical ventilation, emphasizing the need for clearer definitions and comparisons in future research.
Review of Evidence: The authors review existing studies to highlight the complexities in attributing diaphragm dysfunction to either critical illness or mechanical ventilation.

Key Findings:

Critical illness may contribute to diaphragm weakness early in the illness course, complicating the assessment of mechanical ventilation's role.
Weakness detected early does not quantify the impact of subsequent ventilation.
Improvements in diaphragm function during ventilation do not confirm that ventilatory management is solely responsible for these changes.
Causal analyses should consider ventilatory management as a time-varying strategy influenced by multiple factors.

Interpretation:

Longitudinal patterns of diaphragm function do not establish a clear causal relationship between mechanical ventilation and diaphragm dysfunction.

Limitations:

Current studies do not successfully isolate the effects of ventilation from those of critical illness.
Existing evidence does not provide a definitive causal hierarchy between critical illness and mechanical ventilation.

Conclusion:

The article advocates for a cautious interpretation of diaphragm dysfunction in critically ill patients, suggesting that both critical illness and ventilatory management play roles.