Which of the following can affect both SSEP and BAER waveforms?

The correct answer is retractor. Retractors can indeed affect both somatosensory evoked potentials (SSEP) and brainstem auditory evoked responses (BAER) waveforms in a surgical setting. When retractors are used during an operation, they can put mechanical pressure on nerves or tissues, which can lead to changes in the waveforms recorded from SSEP and BAER tests.

For SSEP, this can happen because the stimulation of sensory pathways may be altered if there is pressure on the nerves used for recording, which can affect the latency and amplitude of the waves observed. Similarly, for BAER, if the retractor impinges on the auditory pathways or the structures surrounding them, it could lead to changes in the auditory signal transmission, thus modifying the BAER response.

In contrast, while grounding pads, blood pressure transducers, and suction can have effects on monitoring, they are less likely to produce a direct mechanical interference with the pathways involved in SSEP and BAER. Grounding pads primarily serve to reduce electrical noise and potential differences, blood pressure transducers are used for monitoring hemodynamics and do not interact directly with neural pathways, and suction is used to clear the surgical field but typically does not exert mechanical pressure