Swan-Ganz catheter monitoring in neurosurgical patients: theoretical and practical aspects

Ruptured nontraumatic fusiform aneurysm of the cavernous carotid presenting with multiple episodes of epistaxis

Epistaxis from rupture of a non-traumatic, cavernous carotid aneurysm is a rare and life threatening event. The evaluation and management of a patient with such a lesion is described. Direct surgical reconstruction of this fusiform aneurysm using an extradural/intradural approach to the cavernous sinus resulted in a satisfactory outcome.

Usefulness of a fiber optic Swan-Ganz catheter to monitor oxygen transport during volume expansion in a patient with ischemic neurologic deficits from aneurysmal subarachnoid hemorrhage

The usefulness of a fiber optic Swan-Ganz catheter to monitor oxygen transport during volume expansion in a patient with ischemic neurologic deficits due to aneurysmal subarachnoid hemorrhage is illustrated. Usefulness of oxygen delivery and oxygen consumption measurements are presented. The role of oxygen transport in addition to cardiac hemodynamics and volume status in the management of these neurologic symptoms is emphasized.

Role of hypervolemic hemodilution in focal cerebral ischemia of rats

This study was designed to better define a protocol for hypervolemic hemodilution in acute cerebral ischemia and investigate the mechanism of action of this therapy. Anesthetized rats (n = 40) were subjected to 6 h of middle cerebral artery (MCA) occlusion. At 45 min after MCA occlusion, each rat received one of the following treatment modalities: (1) control, (2) isovolemic hemodilution, (3) hypervolemic nonhemodilution (whole blood), (4) hypervolemic hemodilution (normal saline), and (5) hypervolemic hemodilution (hetastarch). Local cerebral blood flow (CBF) was determined with hydrogen clearance technique, and cardiac output was assessed by measuring the descending aorta blood flow (DAF). Infarction volume was estimated by 2,3,5-triphenyltetrazolium chloride staining method. Hetastarch infusion increased both DAF and local CBF more than the other treatments, by 98% and by 89%, respectively. Hetastarch also reduced infarction volume the most to 71 +/- 19 mm3 (p < 0.01 versus control 117 +/- 32 mm3). A significant correlation between percent (%) changes in local CBF and % changes in DAF existed in ischemic brain regions, and the hetastarch infusion improved local CBF more prominently in profoundly ischemic regions in contrast to isovolemic hemodilution. These data demonstrated the superiority of hypervolemic hemodilution with hetastarch as compared to other similar treatment modalities for acute cerebral ischemia, and indicate that cardiac output augmentation may be more responsible than decreased blood viscosity for the beneficial effect of hypervolemic hemodilution on local CBF in profoundly ischemic regions, as such ischemic brain tissue can severely lose its regulatory control of CBF to alterations in cardiac output.

Normovolaemic induced hypertension therapy for cerebral vasospasm after subarachnoid haemorrhage

We showed that normovolaemic induced hypertension therapy was effective in reducing ischaemic symptoms attributed to cerebral vasospasm in 41 patients after subarachnoid haemorrhage. By inducing hypertension to 25% to 50% above normal systolic arterial blood pressure, we observed that in 17 of 24 cases (71%) neurological deficits improved. In four cases of haemorrhagic infarction, the blood pressure rose to over 50% of systolic arterial pressure, and a low density area was confirmed on computerized tomography (CT) scan prior to vasospasm. Induced hypertension was therefore not considered when a low density area was revealed on CT scan. Restriction of fluid input is usually a factor in producing hypovolaemia after a neurosurgical operation. Intravascular volume expansion has been reported effective in reversing ischaemic deficits. However, according to Poiseuille's equation, increasing blood volume to a state of hypervolaemia can not enhance flow. The cerebral blood flow (CBF) was raised by increasing perfusion pressure, reducing viscosity, or increasing blood vessel diameter. Intravascular volume expansion elevates not only systemic arterial pressure, but also pulmonary artery wedge pressure over 18 mmHg and cardiac index over 2.2. Since pulmonary oedema and congestive heart failure may develop, one should monitor haemodynamic parameters with the Swan-Ganz catheter as a preventive measure. We emphasize that normovolaemic induced hypertension, maintaining haemodynamics subset 1 of the comparable haemodynamic subsets, is effective in raising perfusion pressure of CBF.