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Chest wall motion before and during mechanical ventilation in children with neuromuscular disease
C E Diaz1, K S Deoras, J L Allen
1Department of Pediatrics, Temple University School of Medicine, Philadelphia, Pennsylvania.
Insights
Mechanical ventilation significantly improves chest wall motion asynchrony in patients with neuromuscular disease. This intervention reduces the work of breathing and supports respiratory muscle function, offering a rationale for its use in managing respiratory fatigue.
Area of Science:
- Respiratory Physiology
- Neuromuscular Disorders
- Mechanical Ventilation
Background:
- Patients with neuromuscular disease often exhibit paradoxical rib cage and abdominal motion, increasing breathing effort and leading to respiratory muscle fatigue.
- Long-term mechanical ventilation is known to alleviate chronic hypercapnia and reduce the work of breathing in this population.
- The specific effects of mechanical ventilation on chest wall motion (CWM) in these patients have not been extensively studied.
Purpose of the Study:
- To assess changes in chest wall motion (CWM) during mechanical ventilation in pediatric and young adult patients with neuromuscular disease and paradoxical breathing.
- To quantify the asynchrony between rib cage (RC) and abdominal (AB) motion before and during mechanical ventilation.
- To evaluate the impact of mechanical ventilation on the paradoxical contribution to tidal volume.
Main Methods:
- Utilized a calibrated respiratory inductive plethysmograph to measure CWM in 5 children and young adults.
- Quantified chest wall asynchrony by measuring the phase shift (theta) between RC and AB motion.
- Calculated the paradoxical compartment's contribution to tidal volume (PC/VT).
Main Results:
- Before ventilation, mean theta was 131 degrees and PC/VT was -27%, indicating significant asynchrony and paradoxical motion.
- During mechanical ventilation, tidal volume increased significantly (p < 0.05), theta decreased to 41 degrees (p < 0.05), and PC/VT shifted to +39% (p < 0.02).
- These findings demonstrate a marked improvement in RC/AB synchrony and a reversal of paradoxical motion contribution.
Conclusions:
- Mechanical ventilation effectively improves rib cage/abdominal asynchrony in pediatric and young adult patients with neuromuscular disease.
- The study suggests that mechanical ventilation assumes a significant role in respiratory pump function for these patients.
- Assessing CWM during ventilation may aid in optimizing ventilator settings for patients with neuromuscular disease and respiratory fatigue.
Abstract:
Patients with neuromuscular disease can display paradoxic motion of the rib cage (RC) and abdomen (AB), which increases the work of breathing and predisposes to respiratory muscle fatigue. Long-term mechanical ventilation can reverse chronic hypercapnea and decrease the work of breathing in these patients. Changes in chest wall motion (CWM) that occur during mechanical ventilation have not been studied. We have assessed CWM using a calibrated respiratory inductive plethysmograph before and during mechanical ventilation in 5 children and young adults with neuromuscular disease and paradoxic breathing at rest. Asynchrony of CWM was quantitated by measuring the phase shift, theta, between RC and AB motion (0 degree = synchronous motion, 180 degrees = paradoxic motion). The volume contribution of the paradoxing compartment to tidal volume (PC/VT) was calculated. Before mechanical ventilation, mean +/- SEM VT was 122 +/- 17 mL, theta was 131 +/- 15 degrees C, and PC/VT was -27 +/- 6%. During mechanical ventilation, VT increased to 274 +/- 47 mL (P < 0.05), theta decreased to 41 +/- 14 degrees (P < 0.05), and PC/VT increased to +39 +/- 9% (P < 0.02). We conclude that mechanical ventilation improves RC/AB asynchrony and reverses the negative contribution to tidal volume of the paradoxing compartment in children and young adults with neuromuscular disease. This implies that mechanical ventilation assumes most or all the role of the respiratory pump in these patients, which provides a rationale for the use of chronic or nighttime ventilation in the treatment of respiratory muscle fatigue. Assessment of CWM may be useful in the determination of optimal ventilator settings in this population.