Guidelines on Subarachnoid Haemorrhage are available from the American Heart Association / American Stroke Association.
Most of the summaries are included below.
The initial bleed
The severity of the initial bleed should be determined rapidly because it is the most useful indicator of outcome after aneurysmal SAH, and grading scales that rely heavily on this factor are helpful in planning future care with family and other physicians
Case review and prospective cohorts have shown that for untreated, ruptured aneurysms, there is at least a 3% to 4% risk of rebleeding in the first 24 hours—and possibly significantly higher—with a high percentage occurring immediately (within 2 to 12 hours) after the initial ictus, a 1% per day to 2% per day risk in the first month, and a long-term risk of 3% per year after 3 months. Urgent evaluation and treatment of patients with suspected SAH are therefore recommended

Diagnosis

1. A high level of suspicion for SAH should exist in patients with acute onset of severe headache
2. CT scanning for suspected SAH should be performed, and lumbar puncture for analysis of CSF is strongly recommended when the CT scan is negative
3. Selective cerebral angiography should be performed in patients with SAH to document the presence and anatomic features of aneurysms
4. MRA and CTA may be considered when conventional angiography cannot be performed in a timely fashion

The degree of neurological impairment using an accepted SAH grading system can be useful for prognosis and triage and should be recorded in the ED. Examples include the Hunt and Hess Scale, Fisher Scale, Glasgow Coma Scale, and World Federation of Neurological Surgeons Scale.
Medical Measures to Prevent Rebleeding After SAH

1. Blood pressure should be monitored and controlled to balance the risk of stroke, hypertension-related rebleeding, and maintenance of cerebral perfusion pressure
2. Bedrest alone is not enough to prevent rebleeding after SAH. It may be considered a component of a broader treatment strategy, along with more definitive measures
3. Although older studies demonstrated an overall negative effect of antifibrinolytics, recent evidence suggests that early treatment with a short course of antifibrinolytic agents combined with a program of early aneurysm treatment followed by discontinuation of the antifibrino- lytic and prophylaxis against hypovolemia and vasospasm may be reasonable, but further research is needed. Furthermore, antifibrinolytic therapy to prevent rebleeding may be considered in certain clinical situations, eg, in patients with a low risk of vasospasm and/or a beneficial effect of delaying surgery.

Surgical treatment

1. Surgical clipping or endovascular coiling should be per- formed to reduce the rate of rebleeding after aneurysmal SAH
2. Wrapped or coated aneurysms and incompletely clipped or coiled aneurysms have an increased risk of rehemorrhage compared with those that are completely occluded and therefore require long-term follow-up angiography. Com- plete obliteration of the aneurysm is recommended whenever possible
3. For patients with ruptured aneurysms judged by an experienced team of cerebrovascular surgeons and endovascu- lar practitioners to be technically amenable to both endovascular coiling and neurosurgical clipping, endovascular coiling can be beneficial. Nevertheless, it is reasonable to consider individual characteristics of the patient and the aneurysm in deciding the best means of repair, and management of patients in centers offering both techniques is probably indicated
4. Although previous studies showed that overall outcome was not different for early versus delayed surgery after SAH, early treatment reduces the risk of rebleeding after SAH, and newer methods may increase the effectiveness of early aneurysm treatment. Early aneurysm treatment is reasonable and is probably indicated in the majority of cases

Management of Cerebral Vasospasm

1. Oral nimodipine is indicated to reduce poor outcome related to aneurysmal SAH. The value of other calcium antagonists, whether administered orally or intravenously, remains uncertain.
2. Treatment of cerebral vasospasm begins with early management of the ruptured aneurysm, and in most cases, maintaining normal circulating blood volume and avoiding hypovolemia are probably indicated
3. One reasonable approach to symptomatic cerebral vasospasm is volume expansion, induction of hypertension, and hemodilution (triple-H therapy)
4. Alternatively, cerebral angioplasty and/or selective intraarterial vasodilator therapy may be reasonable after, together with, or in the place of triple-H therapy, depending on the clinical scenario

Management of Hydrocephalus
Temporary or permanent CSF diversion is recommended in symptomatic patients with chronic hydrocephalus after SAH
Ventriculostomy can be beneficial in patients with ven- triculomegaly and diminished level of consciousness after acute SAH
Management of Seizures
The administration of prophylactic anticonvulsants may be considered in the immediate posthemorrhagic period
Management of Hyponatremia

1. Administration of large volumes of hypotonic fluids and intravascular volume contraction should generally be avoided after SAH
2. Monitoring volume status in certain patients with recent SAH using some combination of central venous pressure, pulmonary artery wedge pressure, fluid balance, and body weight is reasonable, as is treatment of volume contraction with isotonic fluids
3. The use of fludrocortisone acetate and hypertonic saline is reasonable for correcting hyponatremia
4. In some instances, it may be reasonable to reduce fluid administration to maintain a euvolemic state

Guidelines for the Management of Aneurysmal Subarachnoid Hemorrhage: A Statement for Healthcare Professionals From a Special Writing Group of the Stroke Council, American Heart Association
Stroke 2009;40;994-1025 (Full Text)
Other AHA Stroke Guidelines