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Updated: Aug 17, 2026
Assessing Rat Diaphragm Motor Unit Connectivity Outcome Measures as Quantitative Biomarkers of Phrenic Motor Neuron Degeneration and Compensation
Published on: April 19, 2024
Twitch airway pressure elicited by magnetic phrenic nerve stimulation in anesthetized healthy children
Gerrard F Rafferty1, Naveed Mustfa, William D Man
1Department of Child Health, Guy's, King's, and St. Thomas' School of Medicine, London, UK. gerrard.rafferty@kcl.ac.uk
Insights
Diaphragm contractility in children was measured using magnetic phrenic nerve stimulation. Results show that diaphragm function in healthy prepubertal children is significantly influenced by age.
Area of Science:
- Pediatric Pulmonology
- Neuromuscular Physiology
Background:
- Diaphragm dysfunction can impair ventilation in children.
- Accurate diagnosis requires appropriate testing and reference ranges.
Purpose of the Study:
- To measure diaphragm contractility in healthy children.
- To investigate the influence of age and maturation on diaphragm function.
Main Methods:
- Magnetic phrenic nerve stimulation (MS) was used to assess diaphragm contractility.
- Airway pressure (TwPaw) was measured during MS in anesthetized children.
- Data were analyzed for bilateral and unilateral responses, and subgroup analysis was performed for prepubertal children.
Main Results:
- Mean TwPaw values were established for bilateral, left unilateral, and right unilateral stimulation.
- Intrapatient coefficients of variation were calculated for reliability assessment.
- Diaphragm contractility (TwPaw) showed a significant positive relationship with age in healthy children.
Conclusions:
- Magnetic phrenic nerve stimulation provides reliable measurements of diaphragm contractility in children.
- Age is a significant factor influencing diaphragm contractility in healthy prepubertal children.
- These findings establish reference ranges for diaphragm function in pediatric populations.
Abstract:
Children with diaphragm dysfunction may be unable to maintain adequate ventilation. Accurate diagnosis is important, but can only be achieved using an appropriate test and reference range. The aim of this study, therefore, was to measure diaphragm contractility and examine the influence of age and maturation, using magnetic phrenic nerve stimulation in healthy children. Anterolateral magnetic stimulation (MS) of the phrenic nerves was performed using a 43-mm figure-eight coil in 23 children (14 male; mean age, 7.8 years; range, 1.8-15.7) anesthetized for minor surgery with sevoflurane gas. The airway was maintained with a cuffed laryngeal mask airway (LMA) which was briefly occluded during MS. Diaphragm contractility was assessed by measuring the airway pressure (TwPaw) elicited by MS. TwPaw responses were obtained in all subjects, with mean (SD) TwPaw 18.2 (6.8) cm H2O bilateral, 7.3 (3.2) cm H2O left unilateral, and 8.6 (3.1) cm H2O right unilateral. Subgroup analysis was performed in 17 of the children who were prepubertal. Their mean (SD) TwPaw was 17.3 (6.8) cm H2O bilateral, 7.1 (3.7) cm H2O left unilateral, and 8.3 (3.3) right unilateral. The mean (SD) intrapatient coefficients of variation for bilateral and left and right unilateral TwPaw were 8.4% (5.2), 6.7% (3.5), and 11.7% (10.3), respectively. Bilateral and left and right unilateral TwPaw were significantly related to age (P < 0.05). In healthy prepubertal children, diaphragm contractility is primarily influenced by age.