The Science Journal of the American Association for Respiratory Care

1998 OPEN FORUM Abstracts

CHEST WALL MOTION IN ADOLESCENTS WITH CONGENITAL NEUROMUSCULAR DISORDERS OFF AND ON VOLUME CYCLED MECHANICAL VENTILATION.

Cherie Johnson, B.S., Sheila Horan, B.S., Robert Warren, M.D., Arkansas Children's Hospital, Little Rock, AR.

The objective of this study was to review changes in chest wall motion in adolescents with congenital neuromuscular disorders obtained during spontaneous breathing and while receiving volume cycled mechanical ventilatory support. The study was a retrospective evaluation of pulmonary function and chest wall motion in patients who had been seen in the Jones Pulmonary Function Laboratory at Arkansas Children's Hospital. Five boys were diagnosed with Duchenne muscular dystrophy and one girl was diagnosed with nemaline rod myopathy. Ages ranged between 15 and 20 years. During a spontaneous breathing period and again while patients were attached to an LP-10 volume ventilator, chest wall measurements (% ribcage, labored breathing index, phase angle, tidal volume, and breaths/min) were made with a calibrated respiratory inductive plethysmograph (Respitrace PT). Ventilator settings were based on the child's weight, age, and expected respiratory frequency. Respiratory Inductive Plethysmography (RIP), is the most widely used technique of body surface measurement of chest wall motion. Results of the study off and on ventilatory support were:

Subject Age %RC LBI Phase VT Breaths/min

off/on off/on off/on off/on off/on

1 20 67/24 1.3/1.1 81/59 495/550 30/33

2 20 78/52 1.2/1.0 37/14 263/770 20/14

3 18 92/63 1.6/1.5 138/53 75/330 16/13

4 15 50/46 1.1/1.0 24/16 316/810 19/12

5 18 59/59 1.0/1.0 13/9 205/430 34/20

6 16 88/25 1.9/1.1 132/40 520/830 17/14

In all subjects, the degree of chest wall motion asynchrony with spontaneous breathing was reduced as measured by one or more of the RIP parameters. All subjects had an increase in VT on mechanical ventilation ranging from 11% to 340%. All subjects had a reduction in respiratory rate. This data suggests that in each of our subjects, the degree of work of breathing as characterized by their spontaneous asynchronous breathing pattern, improved with mechanical ventilatory support. Data obtained from RIP may further be useful in determining ventilatory settings in the individual patient.

The 44th International Respiratory Congress Abstracts-On-DiskĀ®, November 7 - 10, 1998, Atlanta, Georgia.

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