Am. J. Respir. Crit. Care Med., Vol 150, No. 4, 10 1994, 1081-1085.
Evidence of dynamic airway compression during cough in tetraplegic patients
M Estenne, A Van Muylem, M Gorini, W Kinnear, A Heilporn and A De Troyer
Chest Service, Erasme University Hospital, Brussels, Belgium.
Although all the well-recognized muscles of expiration are paralyzed after
traumatic transection of the lower cervical cord, tetraplegic subjects can
still empty their lungs actively by contracting the clavicular portion of
the pectoralis major. It is not known, however, whether contraction of this
muscle bundle may raise pleural pressure enough to cause dynamic
compression of the intrathoracic airways, which is critical for the
production of an effective cough. To investigate this question, we measured
expiratory flow rate and esophageal pressure during a series of forced
expiratory vital capacity (VC) maneuvers in twelve subjects with C5-8
traumatic tetraplegia and constructed isovolume-pressure flow (IVPF)
curves. The curves were interpretable with certainty in nine patients.
Three of them did not show any plateau of flow. On the other hand, six
patients had clearcut plateaus of flow on all IVPF curves between 80-60 and
20% VC, suggesting they had dynamic airway compression. Videoendoscopic
recordings in two patients confirmed trachea and main bronchi collapse
during forced expiration and cough. We conclude, therefore, that
contraction of the pectoralis major causes dynamic airway compression
during expiratory efforts in a substantial proportion of tetraplegic
subjects. Increasing the pressure- generating capacity of this muscle might
thus improve the effectiveness of cough and reduce the prevalence of
bronchopulmonary infections.
