| Blood flow | At 20 mL/min/100 g cerebral blood flow cortical SSEPs decreaseAt 15 mL/min/100 g regional cerebral blood flow cortical SSEPs are totally lost |
| Temperature | Cortical SSEPs are very sensitive to changes in body temperatureIncreasing in latency of MEPs at 32°CCold irrigation of neuronal tissues alters EPs |
| Blood rheology | Amplitude of SSEPs increase in mild anemia. At hematocrit of 10%–15% latency of EPs increase |
| Intracranial pressure | Raised intracranial pressure causes increasing in latency and decreasing in amplitude of EPs |
| Ventilation | Hypoxia alters EPs. Altered SSEPs at PCO2 <20 mmHg |
| s-glucose, Na+, K+ | Should keep normal values to ensure normal neuronal function |