Cholinergic bronchomotor tone and airway caliber in tetraplegic patients

Abstract

Study design: Case-control study. Objectives: To evaluate the resting airway caliber in subjects with tetraplegia; to define the participation of cholinergic innervation in this condition; and to determine if baclofen modifies this pattern. Setting: A rehabilitation hospital, Brası´lia, Brazil. Methods: We studied 18 tetraplegic patients, with complete motor loss between C4 and C8, and 18 healthy control subjects by measuring airway conductance, before and after inhaled ipratropium bromide. Results: At baseline, the pulmonary function parameters revealed mild-to-moderate restrictive impairment in tetraplegic patients as defined by decreases in total lung capacity and predicted percent of slow vital capacity. The average baseline specific airway conductance (sGaw) was less in tetraplegic patients (0.2570.11) than in the control group (0.4170.10 l/s/cm H 2 O) (Po0.0001). All patients had improved postbronchodilator sGaw X40% compared with only four of the 18 controls (Po0.001). The average increase for tetraplegic patients was 235% (793) versus 25% (724) for controls (Po0.0001). Analysis of variance for repeated measurements showed significant difference in sGaw between the control and spinal cord injury (SCI) groups (Po0.0001) following bronchodilator challenge, but found no difference for total gas volume. No difference for mean basal sGaw and bronchodilator challenge was encountered comparing tetraplegic patients using baclofen to those not using it. Conclusions:Cervical SCI patients have a reduced baseline conductance compared to controls. Marked improvement occurs after an inhaled anticholinergic drug. This behavior was not affected by the use of baclofen. The study adds support to the hypothesis of an increased cholinergic bronchomotor tone in tetraplegic patients.

Respiratory Management in the Patient with Spinal Cord Injury

“…Bronchospasms are continuous in patients with cervical SCI due to autonomic changes in the acute phase, with a predominance of vagus nerve tone. Bronchospasms respond well to beta-2 agonists and inhaled anticholinergic agents [93], with beneficial effects on FEV1, FVC, and PEF [94]. Their use is widely recommended and should be started before bronchospasms are apparent [6, 92] There is no question that bronchoscopy with alveolar lavage is an effective method for removing secretions, but it is not exempt from complications such as tracheobronchial irritation, edema, and aspiration.…”

The use of bronchodilators in people with recently acquired tetraplegia: a randomised cross-over trial

“…[3][4][5][6][7] The physiological basis for bronchoconstriction in people with established tetraplegia is debated, although it is most commonly attributed to loss of supraspinal control of the sympathetic nervous system. 8 The sympathetic nervous system is important for dampening parasympathetic nervous system activity. Without its dampening effects, the parasympathetic nervous system can stimulate the bronchial smooth muscles causing bronchoconstriction.…”

“…This may last for 1-3 months. 8 It is not clear how loss of reflex-mediated sympathetic activity in the first few months after injury affects a patient's response to bronchodilator therapy. The purpose therefore of this study was to determine the immediate effects of bronchodilator therapy on respiratory function in people with recently acquired tetraplegia.…”