Narrative review: ventilator-induced respiratory muscle weakness

Area of Science:

• Critical Care Medicine
• Pulmonary Medicine
• Respiratory Physiology

Background:

• Mechanical ventilation can cause lung injury through excessive pressure.
• Emerging evidence suggests that insufficient respiratory muscle workload during ventilation also leads to significant injury.

Purpose of the Study:

• To review the current understanding of ventilator-induced respiratory muscle injury (VIRMI).
• To highlight the potential for diaphragmatic atrophy and weakness due to prolonged inactivity during mechanical ventilation.

Main Methods:

• Review of animal research demonstrating muscle atrophy from inactivity.
• Analysis of human data showing significant decreases in diaphragmatic fiber size after short periods of inactivity.
• Discussion of the proposed mechanisms, including oxidative stress and protein degradation pathways.

Main Results:

• Animal studies confirm that diaphragmatic inactivity causes severe muscle injury and atrophy.
• Human data indicate that 18–69 hours of complete diaphragmatic inactivity can halve the cross-sectional area of muscle fibers.
• Oxidative stress appears to be a key factor in the development of atrophic injury.

Conclusions:

• Ventilator-induced respiratory muscle injury is an emerging concern in critical care.
• Current scientific understanding is insufficient for definitive clinical recommendations.
• Clinicians should aim for ventilator settings that prevent both excessive patient effort and excessive muscle rest, using airway pressure waveforms as a guide.