Subarachnoid hemorrhage from sudden gravitational changes.

Diffuse subarachnoid hemorrhage is commonly attributed to the rupture of intracranial aneurysms or other vascular malformations. Non-aneurysmal hemorrhages often have a characteristic pattern or clear mechanism (e.g. trauma) with an often more benign clinical course. We report the case of a diffuse non-aneurysmal subarachnoid hemorrhage due to sudden gravitational changes encountered during complex airflight maneuvers, complicated by hydrocephalus and cerebral vasospasm. This case illustrates a rare phenomenon that may again be encountered in the future with the advent and advancement of civilian spaceflight.

Predictors of apnea test failure during brain death determination.

BACKGROUND: In a recent publication (Wijdicks et al. in Neurology 71(16):1240, 2008), apnea test safety during brain death determination was evaluated at a single tertiary care center. One major conclusion was that apnea testing was safe in hemodynamically compromised patients in most circumstances and rarely aborted. Determinants of apnea test completion failure are unknown. METHODS: A-a gradients and PaO2/FiO2 ratios were calculated in the previously studied cohort. Arterial blood gas (ABG) values and systolic blood pressures (SBP) were recorded prior to apnea test initiation. Patients that completed the procedure during the declaration of brain death were compared to those whose studies were aborted. Statistical analysis was performed using Wilcoxon rank-sum and Fisher's exact tests where appropriate. Aborted apnea test risk factor assessment was by logistic regression analysis. RESULTS: 207 of the original 228 patients were evaluated. 10 of the 207 patients had aborted apnea tests because of hypoxemia and/or hypotension. 60% who failed the apnea test were male and were of younger age [median: 23 years vs. median: 47 years (P = 0.02)]. A-a gradient median values for aborted and completed apnea tests were 376 and 175 mmHg, respectively (P = 0.003). Neither the PaO2/FiO2 ratio (P = 0.14) nor SBP (P = 0.28) were associated with test completion failure. Acidemia preceding a carbon dioxide challenge was independently associated with test completion failure (P = 0.028). CONCLUSION: Acute lung injury is common in patients undergoing brain death evaluation. Patients that failed completion of apnea testing tended to be younger, had significantly greater A-a gradients, and were more acidotic.

Indicators of Subarachnoid Hemorrhage as a Cause of Sudden Cardiac Arrest.

Subarachnoid hemorrhage (SAH) may present with cardiac arrest (SAH-CA). We report a case of SAH-CA to assist providers in distinguishing SAH as an etiology of cardiac arrest despite electrocardiogram findings that may be suggestive of a cardiac etiology. SAH-CA is associated with high rates of return of spontaneous circulation, but overall poor outcome. An initially non-shockable cardiac rhythm and the absence of brain stem reflexes are important clues in indentifying SAH-CA.

Multidisciplinary management and emerging therapeutic strategies in aneurysmal subarachnoid haemorrhage.

The management of patients with aneurysmal subarachnoid haemorrhage demands expertise to anticipate, recognise, and promptly treat the many neurological and systemic complications. For this reason, these patients are best cared for in high-volume medical centres with multidisciplinary teams and should preferably be treated in a specialised intensive care unit. Endovascular occlusion and surgical clipping provide complementary alternatives for the treatment of aneurysms. Perfusion scans are redefining the way we detect delayed ischaemia as a growing body of evidence indicates that monitoring vessel diameter is insufficient to prevent cerebral infarctions. Statins, endothelin antagonists, and magnesium sulfate infusion are among the novel strategies being tested for neuroprotection and attenuation of vasospasm. The effectiveness of these treatments is supported by strong experimental data and they represent a new generation of therapeutic options developed from the understanding that vasospasm is primarily caused by endothelial dysfunction.