Hyponatremia, volume status and blood pressure following aneurysmal subarachnoid hemorrhage

Patients who survive an aneurysmal subarachnoid hemorrhage (SAH) are endangered by complications, which especially occur during the first weeks after the hemorrhage. These complications have a high mortality and morbidity, and the outcome of patients with SAH will improve if these complications can be prevented or if the neurological deterioration caused by these complications can be reversed. To achieve this, it is of the utmost importance to distinguish between the different causes of deterioration after SAH. For instance, if a patient has an impaired level of consciousness a few days after the initial hemorrhage, while there were no abnormalities during the days before, this patient might have had a rebleed, cerebral ischemia, hydrocephalus or other, less common complications. In our department all such patients were under continuous observation in an intensive care unit. If a deterioration had occurred, the time course was documented, the patient was examined and a CT scan was repeated. The serum sodium levels were also measured in these patients, since it is known that hyponatremia may occur after SAH and can lead to neurological deficits. A low serum sodium level never appeared to be the direct cause of a deterioration, probably because the sodium levels decreased gradually and were never under 120 mmol/liter. However, we had the impression that patients with hyponatremia did worse than others. I decided to investigate whether SAH patients with hyponatremia did indeed have a particularly poor outcome, how and why hyponatremia develops and how it can be prevented. These questions are the subject of this thesis.