What condition is this?
PT has a spinal cord injury at the thoracic level of T6 or above.
PT gets a full bladder and needs to be cathed. The full bladder causes a sympathetic reflex. When the sympathetic system discharges, the blood vessels constrict. (normally, the reflex is meant to go up to brain and communicate that we need to get rid of urine but the sympathetic goes out and meets the injury but cannot bypass it and tell the brain what is going on) instead, it elicits the sympathetic reflex arc below the level of injury, so all the blood vessels below the level of injury start constricting, leading to an increased BP. Hypertension then occurs, and the baroreceptors sense that raise in BP and attempts to stimulate the vagus nerve, which will go down and slow the heart rate. Unfortunately, the vagus nerve cannot control the blood vessels below the level of injury, so the hypertension below the level on injury is not mediated and keeps going up. Hypertension continues to increase but heart rate continues to decrease. Above the level of injury, there is parasympathetic dominance, but below the level of injury, there is sympathetic dominance;
The blood vessels above the level of injury then dilate (parasympathetic action)[