EFFECTS OF ENDOTRACHEAL INTUBATION ON AIRWAY NEUROPEPTIDE CONTENT, ARTERIAL OXYGENATION AND LUNG-VOLUMES IN ANESTHETIZED RATS

Background General anaesthesia affects lung volume and pulmonary gas e xchange. What role is played by mechanical stimulation by the endotrac heal tube? Methods Me investigated the effects of intubation on arteri al oxygenation and lung volume in rats. Results Endotracheal intubatio n caused an increase in PA-ao(2) and volume of trapped gas in the lung . This was accompanied by a reduction in neuropeptides and calcitonin gene-related peptide (CGRP) in trachea, bronchi and lung, and in vasoa ctive intestinal peptide (VIP) in the trachea. The increase in PA-ao(2 ) and volume of trapped gas due to intubation was not altered in the a nimals given capsaicin, in which neuropeptide levels were reduced. Con clusions These data suggest that the decrease in CGRP and VIP content in the airway tissues may be one of the consequences, but not the caus e, of impaired gas exchange by endotracheal intubation. The increase i n volume of trapped gas in the lung is apparently not mediated by acti vation of capsaicin-sensitive sensory nerves.