Faculty Collaboration Database

Dose-dependent effects of halothane on the carbon dioxide responses of expiratory and inspiratory bulbospinal neurons and the phrenic nerve activities in dogs. Anesthesiology 1994 Dec;81(6):1470-83

Date

12/01/1994

Pubmed ID

7992917

DOI

10.1097/00000542-199412000-00023

Scopus ID

2-s2.0-0027948491 (requires institutional sign-in at Scopus site)   29 Citations

Abstract

BACKGROUND: Expiratory bulbospinal and inspiratory bulbospinal neurons in the ventral respiratory group provide drive for thoracoabdominal expiratory and phrenic and thoracic inspiratory motor neurons. Potent inhalational agents such as halothane may have differential effects on inspiratory and expiratory neurons, but detailed studies comparing neurons at a homologous level are lacking.

METHODS: The dose-dependent effects of anesthesia with 1.0-2.5 minimum alveolar concentration halothane on the CO2 responses of single expiratory and inspiratory bulbospinal neurons of the ventral respiratory group and on phrenic neural activities were studied in nonpremedicated, anesthetized, paralyzed, vagotomized dogs. Hyperventilation with O2 and the addition of CO2-O2 mixtures were used to produce low, medium, and high steady-state levels of central CO2 drive.

RESULTS: Peak neuron discharge frequency decreased progressively with increasing halothane dose at all levels of CO2 drive for both types of neurons. The sensitivities of inspiratory and expiratory bulbospinal neuronal activities to halothane were not significantly different from one another, whereas the sensitivity to halothane of the peak phrenic activity was markedly greater than those of the neurons. Increasing halothane dose caused a downward, predominantly parallel shift of the CO2 response curves. Phrenic nerve activity also showed a decrease in slope of the CO2 response.

CONCLUSIONS: The activities of respiratory premotor neurons are less depressed by increasing doses of halothane than is phrenic nerve activity. The greater depression of phrenic activity may result from additional anesthetic actions on the efferent motor pathways, resulting in decreased descending synaptic inputs to phrenic motor neurons.

Author List

Stuth EA, Tonkovic-Capin M, Kampine JP, Bajic J, Zuperku EJ

Authors

Jurica Bajic MD, PhD Assistant Professor in the Anesthesiology department at Medical College of Wisconsin
Eckehard A. Stuth MD Professor in the Anesthesiology department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Animals
Carbon Dioxide
Dogs
Dose-Response Relationship, Drug
Electrophysiology
Halothane
Medulla Oblongata
Motor Neurons
Phrenic Nerve
Respiration
Spinal Cord
Vagotomy