Multi-modality evoked potentials in hypoxaemia.

The auditory nerve-brain-stem evoked response (ABR) has been shown to be insensitive to hypoxic inspiratory gas mixtures which severely depress the EEG. In order to determine the relative sensitivities of additional brain regions and pathways to hypoxaemia, anaesthetized paralysed cats were ventilated with various gas mixtures while recording the evoked responses of the auditory, somatosensory (including peripheral nerve, brain-stem and primary cortical components), visual and vestibular systems. Arterial blood pressure was maintained by dopamine infusion and pH was corrected with bicarbonate.