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Correspondence  |   March 1995
Effect of Pulmonary Sympathetic Blockade on Bronchial Responsiveness
Author Notes
  • Peter V. Dicpinigaitis, M.D., Assistant Professor, Department of Medicine, Albert Einstein College of Medicine, 1825 Eastchester Road Bronx, New York 10461.
  • Peter L. Almenoff, M.D., Assistant Professor, Department of Medicine, Mount Sinai School of Medicine, VA Medical Center (111), 130 W. Kingsbridge Road, Bronx, New York 10468.
Article Information
Correspondence
Correspondence   |   March 1995
Effect of Pulmonary Sympathetic Blockade on Bronchial Responsiveness
Anesthesiology 3 1995, Vol.82, 794. doi:
Anesthesiology 3 1995, Vol.82, 794. doi:
To the Editor:—A recent article by Groeben et al. [1 ] suggested that high thoracic epidural anesthesia did not alter airway resistance and attenuated the response to inhaled acetylcholine challenge in patients with preexistent bronchial hyperresponsiveness. In light of other recently published data, the results of this study are unexpected.
The parasympathetic nerve supply of the lungs arises in the vagal nuclei of the brainstem, from which efferent fibers pass down the vagus nerve to synapse in ganglia within the airway wall. Sympathetic pulmonary innervation originates from the upper six thoracic ganglia. Although human airways appear to lack tonic sympathetic broncho-dilator tone, it is believed that sympathetic nerves in the lung act in a neuromodulatory capacity, serving to counteract a cholinergic bronchoconstrictor effect. [2 ] A situation that produces selective blockade of sympathetic input to the lung therefore would be expected to enhance bronchial responsiveness. Such is the case in cervical spinal cord injury (quadriplegia), in which transection of the cervical spine interrupts sympathetic pulmonary innervation, resulting in unopposed cholinergic airway tone. We have demonstrated the uniform presence of bronchial hyperresponsiveness to inhaled methacholine in subjects with chronic cervical spinal cord injury, who were lifetime nonsmokers without history of respiratory injury. [3 ] Subjects with lesions of the lower thoracic (below T6) and lumbar spine displayed normal bronchial reactivity. [4 ] Our explanation of these findings on the basis of unopposed parasympathetic airway innervation is supported by recent animal studies. Using a guinea pig model, Hey et al. [5 ] induced vagal cholinergic bronchoconstriction by electrical stimulation of structures within the rostral region of the dorsal medulla. Interruption of the bulbospinal sympathetic neuronal pathways by administration of lidocaine directly into the spinal cord at the first cervical level potentiated the bronchoconstrictor response, as did bilateral adrenalectomy. [6 ] In adrenalectomized animals, injection of lidocaine into the spinal cord or administration of intravenous propranolol further potentiated bronchospasm, thereby suggesting the presence of sympathetic inhibitory neural modulation of electrically induced cholinergic bronchoconstriction independent of circulating catecholamines. [6 ].
These contradictory findings demonstrate the need for further elucidation of the functional significance of pulmonary sympathetic innervation in bronchial reactivity.
Peter V. Dicpinigaitis, M.D., Assistant Professor Department of Medicine Albert Einstein College of Medicine 1825 Eastchester Road Bronx, New York 10461.
Peter L. Almenoff, M.D., Assistant Professor Department of Medicine Mount Sinai School of Medicine VA Medical Center (111) 130 W. Kingsbridge Road Bronx, New York 10468.
REFERENCES
Groeben H, Schwalen A, Irsfeld S, Tarnow J, Lipfert P, Hopf H-B: High thoracic epidural anesthesia does not alter airway resistance and attenuates the response to an inhalational provocation test in patients with bronchial hyperreactivity. ANESTHESIOLOGY 81:868-874, 1994.
Barnes PJ: Neural control of human airways in health and disease. Am Rev Respir Dis 134:1289-1314, 1986.
Dicpinigaitis PV, Spungen AM, Bauman WA, Absgarten A, Almenoff PL: Bronchial hyperresponsiveness after cervical spinal cord injury. Chest 105:1073-1076, 1994.
Singas E, Spungen AM, Bauman WA, Lesser MD, Absgarten A, Almenoff PL: A comparison of bronchial reactivity in subjects with quadriplegia and paraplegia (abstract). Am J Respir Crit Care Med 149:A901, 1994.
Hey JA, del Prado M, Chapman RW: Activation of a novel medullary pathway elicits a vagal, cholinergic bronchoconstriction in guinea-pigs. Pulmon Pharmacol 3:53-54, 1990.
Hey JA, del Prado M, Chapman RW: Central nervous system control of bronchomotor tone: Pharmacological characterization of parasympathetic constrictor and sympathetic inhibitory responses in guinea-pigs. J Auton Pharmacol 13:341-350, 1993.