Pattern of respiration and responses to carbon dioxide during trichloroethylene anaesthesia in the cat

Tidal volume (VT), minute ventilation (VE), the duration of inspiratats anaesthetized with 0.7%, 1% and 1.5% (inspired) trichloroethylene (TCE). The tracheal cannula was occluded at intervals at the start of inspiration and the tracheal pressure was measured to assess the force of contraction of the respiratory muscles. Anaesthesia with TCE 0.7% was associated with an increase in VE, a reduction in VT, and a marked increase in respiratory frequency and mean inspiratory flow rate, but PaCO2 values did not differ significantly from those in conscious animals. Ventilation was also greater than in conscious animals during anaesthesia with TCE 1%. TCE 1.5% caused a significantly greater PaCO2 than in conscious animals. All concentrations of TCE caused a reduction in the ventilatory response to carbon dioxide, measured by the steady-state method. Cervical vagal section did not abolish the tachypnoea caused by TCE.