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Biomedical subjects

M N Diringer

Publications and source records attributed to M N Diringer.

At least 37 records · Page 2Linked to original sources
PubMed1998

Autoregulatory vasodilation of parenchymal vessels is impaired during cerebral vasospasm.

Impaired CBF autoregulation during vasospasm after aneurysmal subarachnoid hemorrhage (SAH) could reflect impaired capacity of distal vessels to dilate in response to reduced local perfusion pressure or simply indicate that the perfusion pressure distal to large arteries in spasm is so low that vessels are already maximally dilated. Autoregulatory vasodilation can be detected in vivo as an increase in the parenchymal cerebral blood volume (CBV). Regional CBV, CBF, and oxygen extraction fraction in regions with and without angiographic vasospasm obtained from 29 positron emission tomography studies performed after intracranial aneurysm rupture were compared with data from 19 normal volunteers and five patients with carotid artery occlusion. Regional CBF was reduced compared to normal in regions from SAH patients with and without vasospasm as well as with ipsilateral carotid occlusion (P < .0001). Regional oxygen extraction fraction was higher during vasospasm and distal to carotid occlusion than both normal and SAH without vasospasm (P < .0001). Regional CBV was reduced compared to normal in regions with and without spasm, whereas it was increased ipsilateral to carotid occlusion (P < .0001). These findings of reduced parenchymal CBV during vasospasm under similar conditions of tissue hypoxia that produce increased CBV in patients with carotid occlusion provide evidence that parenchymal vessels distal to arteries with angiographic spasm after SAH do not show normal autoregulatory vasodilation.

Adult↗
PubMed1998

Effects of induced hypertension on transcranial Doppler ultrasound velocities in patients after subarachnoid hemorrhage.

BACKGROUND AND PURPOSE: Transcranial doppler ultrasound (TCD) is used after subarachnoid hemorrhage to detect cerebral vasospasm and is often treated with induced hypertension. Cerebral autoregulation, however, may be disturbed in this population, raising the possibility that TCD velocities may be elevated by induced hypertension. To study this possibility, we performed continuous TCD monitoring of the middle cerebral artery during the induction and withdrawal of induced hypertension in patients after subarachnoid hemorrhage. METHODS: Twenty-eight patients were studied during the induction and withdrawal of hypertension using primarily phenylephrine. Continuous monitoring was performed on the middle cerebral artery with the highest flow velocity. Treatment was based on rising TCD velocities or clinical evidence for cerebral vasospasm. Mean arterial pressure and mean TCD velocities were recorded every minute. A change of > 15% from starting TCD values was considered significant. Cerebral autoregulation was calculated as a percentage of intact autoregulation. Patients were subsequently divided into groups of disturbed and intact autoregulation. RESULTS: In 10 of 19 patients (53%), TCD velocities changed by > 15% and paralleled changes in mean arterial pressure. This directly altered the TCD interpretation of the grade of vasospasm in 7 of 19 patients (36%). Three additional patients had smaller absolute changes in TCD velocities. No clinical difference could be identified between patients with disturbed and intact autoregulation. CONCLUSIONS: In patients with disturbed autoregulation after subarachnoid hemorrhage, induced hypertension can alter cerebral blood flow velocities. The level of autoregulation needs to be considered when interpreting TCD velocities in patients after subarachnoid hemorrhage.

Adult↗
PubMed1998

Hydrocephalus: a previously unrecognized predictor of poor outcome from supratentorial intracerebral hemorrhage.

BACKGROUND AND PURPOSE: Although several factors have been identified that predict outcome after intracerebral hemorrhage (ICH), no previous study has investigated the impact of hydrocephalus. The purpose of this study was to determine whether the presence of hydrocephalus after ICH would predict mortality and functional outcome. METHODS: Patients with spontaneous supratentorial ICH were identified in our prospectively collected database to determine the following: age, sex, race, past medical history; Glasgow Coma Scale (GCS) score and blood pressure on admission; use of mechanical ventilation, mannitol, and ventriculostomy; and medical complications. CT scans performed within 24 hours of hemorrhage were retrospectively analyzed to determine lesion size and location, pineal shift, cisternal effacement, intraventricular hemorrhage (IVH), and hydrocephalus. Outcome was determined with use of hospital disposition (dead, nursing home, rehabilitation, home) and functional outcome (Functional Independence Measure [FIM]) at 3 months. Patients with and without hydrocephalus were compared and univariate and multivariate analyses performed to determine whether hydrocephalus was an independent predictor of mortality. Data are presented as mean+/-SD. RESULTS: Of the 81 patients studied, 40 had hydrocephalus. Those with hydrocephalus were younger (57+/-15 versus 67+/-15 years), had lower GCS scores (8.2+/-4.2 versus 11+/-2.9), were more likely to have ganglionic or thalamic hemorrhages, and were intubated more frequently (70% versus 27%). Hospital mortality was higher in patients with hydrocephalus (51% versus 2%), and fewer patients went home (21% versus 35%). Those who died had higher hydrocephalus scores (9.67+/-7.1 versus 5.75+/-4.5). Outcome was no different if a ventriculostomy was placed. The final logistic regression model included hydrocephalus score, gender, GCS, and pineal shift, and it correctly predicted 85% of patients as dead or alive. Multivariate analyses indicated that hydrocephalus is an independent predictor of mortality. CONCLUSIONS: We conclude that hydrocephalus is an independent predictor of mortality after ICH.

Adolescent↗
PubMed1998

Response to external ventricular drainage in spontaneous intracerebral hemorrhage with hydrocephalus.

We retrospectively reviewed consecutive intensive care unit patients with spontaneous supratentorial intracerebral hemorrhage (i.c.h.) and hydrocephalus who were treated with ventriculostomy to determine intracranial pressure (i.c.p.), Glasgow Coma Scale (GCS) score, and ventricular volume before and after ventriculostomy. Of 22 patients studied, ICP was controlled at < 20 mm Hg in 20. Only one patient had an improvement in both hydrocephalus and GCS. The three patients who survived to 3 months (modified Rankin scores of 0, 0, and 1) were characterized by very small ICH volumes and stable or improving hydrocephalus and GCS.

Adult↗
PubMed1998

Mechanical ventilation for ischemic stroke and intracerebral hemorrhage: indications, timing, and outcome.

OBJECTIVE: To compare the incidence, indication, and timing of intubation and outcome in patients with cerebral infarction (ISCH) and intracerebral hemorrhage (HEM) requiring mechanical ventilation (MV). BACKGROUND: Poor outcomes have been reported for ISCH patients requiring MV. Because the target population, pathophysiology, and management of ISCH and HEM patients differ considerably, we compared the characteristics of patients with ISCH and HEM who required MV. METHODS: A retrospective review of ISCH and HEM stroke patients who underwent MV at a tertiary care academic center from 1994 to 1997 was performed to determine age, sex, type, and location of stroke (anterior or posterior circulation); brainstem dysfunction at intubation (pupillary, corneal, and oculocephalic reflexes); indication for intubation (neurologic deterioration, cardiopulmonary deterioration, or elective intubation for surgery); timing of intubation (on presentation or later); comorbidities; and outcome (hospital disposition). RESULTS: A total of 230 patients, 74 with ISCH and 156 with HEM (mean age, 61 +/- 16 years; male-to-female ratio, 1.15:1), underwent MV. Intubation rates were 6% for ISCH patients and 30% for HEM patients. Two-thirds of the patients required intubation on presentation (84% were intubated for neurologic deterioration) and 131 patients (57%) died (ISCH, 55%; HEM, 58%). Signs of brainstem dysfunction predicted a higher mortality for both groups. Additionally, early intubation and older age predicted mortality for HEM, and male gender predicted mortality in ISCH. Stroke location and comorbidities did not influence outcome. CONCLUSIONS: MV in acute stroke is associated with high mortality. Mortality and outcome were similar for ISCH and HEM; however, the factors predictive of outcome may differ and influence decisions about the use of MV in such patients.

Adult↗
PubMed1998

Increase in diameters of vasospastic intracranial arteries by intraarterial papaverine administration.

OBJECT: This study was conducted to determine if there is a change in intracranial arterial diameters after papaverine infusion for vasospasm and to determine whether the change occurs in proximal, intermediate, and distal arteries. METHODS: The authors measured arterial diameters retrospectively in all patients who received intraarterial papaverine for treatment of vasospasm between November 1992 and August 1995. Patients who received papaverine in the same session with or following angioplasty were excluded. Measurements were made in a blinded manner with the aid of a magnification loupe at 12 predetermined sites on each angiogram before and after papaverine infusion. Eighty-one treatments in 34 patients were included. Angiograms obtained at the time of presentation with subarachnoid hemorrhage (SAH) were examined in 26 of the 34 patients. Nine carotid territories visualized by repeated angiography on the day after infusion were examined to determine the duration of the papaverine effect. CONCLUSIONS: In all treatment groups an increase was found in the average arterial diameters ranging from 2.8 to 73.9%, with a mean increase of 26.5%. Increases in diameter were observed in proximal, intermediate, and distal arteries. The timing of treatments ranged from Day 3 to Day 19 post-SAH, and there was no relationship between timing and arterial responsiveness (r = -0.06). There was a moderately good correlation between the degree of vasospasm in an artery and its responsiveness to papaverine (r = -0.54, -0.66, and -0.66, for proximal, intermediate, and distal arteries, respectively). The effect of papaverine did not persist until the following day in patients in whom repeated angiography was performed.

Angiography, Digital Subtraction↗
PubMed1998

Middle cerebral artery territory infarction and early brain swelling: progression and effect of age on outcome.

OBJECTIVE: To determine the clinical course and outcome in patients with a middle cerebral artery (MCA) occlusion and early computed tomographic (CT) scan findings of infarction, particularly relative to age of the patient. MATERIAL AND METHODS: The clinical and neuroimaging features of 42 consecutive patients with MCA occlusion and early CT signs of swelling (within 24 hours after ictus) were studied. CT scans were graded for displacement of the pineal gland and septum pellucidum as well as compression of the frontal horn of the ventricular system. Young adults, defined as younger than 45 years of age, were assessed separately. RESULTS: Overall mortality was 55% in this patient population at risk for further neurologic deterioration. Of the 42 patients, 33 had deterioration-an impaired level of consciousness ensued in 3, a diencephalic herniation syndrome developed in 19, and uncal herniation occurred in 11. Mortality was 70% in these patients with deterioration. Mortality was significantly lower in younger patients with deterioration in comparison with older patients (3 of 11 patients versus 20 of 22; P = 0.00018, Fisher's exact test). Factors predictive of deterioration and poor outcome were older age (more than 45 years) and the presence of hyperdense clot in the MCA on CT scan, in addition to early swelling. CONCLUSION: Deterioration from further brain swelling is common in patients with MCA occlusion and sulci effacement on early CT scan. The outcome is fatal in most patients who deteriorate. Mortality was significantly higher in deteriorating older patients than in younger patients. Clearly defined criteria for decompressive hemicraniotomy in young patients with complete MCA occlusion are needed, preferably derived from a randomized clinical trial.

Adult↗
PubMed1998

Intracranial pressure monitoring during intraarterial papaverine infusion for cerebral vasospasm.

PURPOSE: Intraarterial papaverine infusions are performed to reverse cerebral arterial vasospasm resulting from subarachnoid hemorrhage, but such infusions may lead to increases in intracranial pressure (ICP). This study was undertaken to determine when ICP monitoring is indicated during papaverine treatment. METHODS: Seventy-eight vessels were treated in 51 sessions in 28 patients with symptomatic vasospasm. ICP, papaverine doses, and infusion rates were recorded during treatment sessions. The procedural data, Hunt and Hess scores, Fisher grades, Glasgow Coma Scale scores, and ages for all subjects were reviewed and analyzed retrospectively. RESULTS: Baseline ICP ranged from 0 to 34 mm Hg. With typical papaverine doses of 300 mg per territory and infusion times ranging from 5 to 60 minutes per vessel, ICP increases above baseline during papaverine infusion ranged from 0 to 60 mm Hg. Significant (> or = 20 mm Hg) ICP increases during therapy were observed even in patients with low baseline ICP and with papaverine infused at the slowest rate. Patients with a baseline ICP of more than 15 mm Hg were much more likely to have significant ICP increases than were patients with a baseline ICP of 0 to 15 mm Hg. Hunt and Hess scores, Fisher grades, age, and Glasgow Coma Scale scores on admission and immediately before treatment did not correlate with ICP increases during papaverine infusion. Patients with ICP increases of more than 10 mm Hg during therapy were more likely to experience adverse clinical events than were patients with ICP increases of < or = 10 mm Hg. Reduction in the rate of papaverine infusion, or termination of infusion, resulted in reversal of drug-induced ICP elevation. CONCLUSION: ICP monitoring during intraarterial papaverine infusions for cerebral vasospasm is recommended for all patients and is particularly important for patients with elevated baseline ICP. Continuous ICP monitoring facilitates safe and time-efficient drug delivery.

Age Factors↗
PubMed1998

Collateral circulation and outcome after basilar artery thrombolysis.

BACKGROUND AND PURPOSE: This study was undertaken to examine the relationship between collateral flow and outcome after local intraarterial thrombolytic treatment for basilar artery thrombosis. METHODS: Twenty-four patients with symptomatic basilar thrombosis were treated with intraarterial urokinase. Angiograms at the time of treatment were analyzed to characterize collateral flow. The number of posterior communicating arteries (PCoAs) and the degree of collateral filling of the basilar artery were then compared with symptom duration before treatment, with Glasgow Coma Scale (GCS) score at the time of treatment, with 90-day modified Rankin score, and with 90-day survival status. RESULTS: Of the 20 patients who had carotid artery injections at the time of the thrombolytic procedure, two had no PCoA, eight had one PCoA, and 10 had two PCoAs. Nine had no collateral opacification of the basilar artery, six had collateral opacification of the distal basilar artery, and five had collateral opacification of the distal and proximal basilar artery. Ninety-day survival was 38%; 25% of patients had good neurologic outcomes. No correlation was found between the number of PCoAs and symptom duration, pretreatment GCS score, survival, or neurologic outcome. Duration of symptoms before treatment was longer in patients with collateral flow to the basilar artery. Basilar artery collateral flow did not correlate with survival, but it did correlate with neurologic outcome for the 12 patients with middle or distal basilar artery thrombus in whom collateral flow to the basilar artery was assessed (83% with collateral flow had good neurologic outcomes, but only 17% without collateral flow had good outcomes). All six patients with proximal basilar artery thrombus in whom collateral flow was assessed died, independent of the collateral flow observed. CONCLUSION: In symptomatic acute basilar artery thrombosis, neurologic outcome was better after intraarterial thrombolysis in patients who had collateral filling of the basilar artery, except in cases of proximal basilar thrombosis. Patients with collateral filling of the basilar artery also tolerated longer symptom duration.

Basilar Artery↗
PubMed1997

Does modification of the Innsbruck and the Glasgow Coma Scales improve their ability to predict functional outcome?

BACKGROUND: The accurate prediction of functional outcome requires the development of multivariate models. To enhance their contribution to such models, the predictive power of each component must be optimized. OBJECTIVES: To improve the predictive power of coma scales as the first step in building more sophisticated multivariate models to predict specific levels of functional outcome. DESIGN: Prospective descriptive study. SETTING: Neurology and neurosurgery intensive care unit (NNICU) in a tertiary care academic center. PATIENTS: Eighty-four patients with acute traumatic brain injury, intracerebral hemorrhage, subarachnoid hemorrhage, or ischemic stroke. INTERVENTIONS: None. MAIN OUTCOME MEASURES: The Glasgow Coma Scale (GCS) and Innsbruck Coma Scale (ICS) were administered within 24 hours of admission to the NNICU and then at 48-hour intervals until discharge of the patient from the NNICU. The assessments were performed by 3 occupational therapy graduate students working under the supervision of the medical director of the NNICU. The functional outcome at 3 months after discharge from the hospital was assessed by telephone by the same nurse using the following categories: (1) dead, (2) receiving nursing home or custodial care, (3) home with help, or (4) independent. Cronbach's alpha estimates of reliability for each scale were computed using all scores obtained during the study. The analyses indicated that the verbal response item of the GCS and the oral automatisms item of the ICS were less reliable in this patient population. The scales were modified by deleting those items, and predictive validity for the original and modified scales was computed using a discriminant function of the admission scores. RESULTS: Before modification, both scales were best at predicting independence (GCS and ICS, 71% correct) and mortality (GCS, 60% correct; ICS, 56% correct). The modifications produced a modest improvement in the ability of both scales to better predict levels of outcome (modified GCS: home with help, 33% correct, independent, 71% correct; modified ICS: home with help, 0% correct, independent, 74% correct). CONCLUSIONS: By deleting items with low reliability from the ICS and the GCS we achieved improved reliability and predictive validity. The improvement in predictive power, however, was inadequate to accurately predict functional outcome. Combining clinical scales with other demographic, physiological, functional, and radiographic data will be needed to achieve useful predictions of functional outcome.

Adult↗
PubMed1997

The use of hyperventilation and its impact on cerebral ischemia in the treatment of traumatic brain injury.

Traumatic brain injury is a common occurrence in the United States, leading to approximately 190,000 deaths or long-term disabilities. Following the primary insult, secondary disturbances in cerebral blood flow (CBF) and metabolism may have deleterious effects on potentially viable neurons. Recent studies evaluating CBF immediately following head injury have revealed flows low enough to produce cerebral ischemia. Hyperventilation is used routinely to lower suspected increased intracranial pressure (ICP). Aggressive hyperventilation produces a marked reduction in CBF, which may give rise to or exacerbate cerebral ischemia, thus enhancing rather than reducing secondary injury. This article reviews the role of hyperventilation in the treatment of increased ICP and its impact on cerebral ischemia following traumatic brain injury.

Animals↗
PubMed1997

Cerebral hemodynamic and metabolic changes caused by brain retraction after aneurysmal subarachnoid hemorrhage.

OBJECTIVE: The cerebral hemodynamic and metabolic effects of aneurysmal subarachnoid hemorrhage are complex. To investigate the impact of surgical retraction, we analyzed position emission tomography (PET) studies that measured the regional cerebral metabolic rate for oxygen, regional oxygen extraction fraction, and regional cerebral blood flow in four patients before and after right frontotemporal craniotomies for clipping of ruptured anterior circulation aneurysms. METHODS: Preoperative studies were conducted 1 day before surgery and postoperative studies 6 to 17 days after surgery. No patient had hydrocephalus or intracerebral hematoma. At the time of the second PET study, none of the patients had signs of clinical vasospasm. Regional measurements were obtained from the right ventrolateral frontal and anterior temporal regions corresponding to the area of retraction and compared to the same regions in the opposite hemisphere. To establish a quantitative means to differentiate between hemodynamic and metabolic changes related to arterial vasospasm and those caused by brain retraction, we studied a second group of preoperative patients, who had undergone PET during angiographic and clinical vasospasm. RESULTS: There was a 45% reduction in regional cerebral metabolic rate for oxygen (1.87 +/- 0.22 to 1.04 +/- 0.28 ml 100 g-1 min-1) and 32% reduction in regional oxygen extraction fraction (0.41 +/- 0.04 to 0.28 +/- 0.03) in the region of retraction but no change in the opposite hemisphere (paired t test; P = 0.042 and 0.003, respectively). There was no change in regional cerebral blood flow in any region. Brain retraction produced a focal area of tissue injury at the site of retractor blade placement, as compared to more diffuse vascular territory changes produced by vasospasm. CONCLUSION: This reduction in the cerebral metabolic rate of oxygen and the oxygen extraction fraction indicates a primary reduction in metabolism and uncoupling of flow and metabolism (luxury perfusion). Similar findings of luxury perfusion have been reported after ischemic stroke and traumatic brain injury. Further studies will be necessary to fully understand the clinical and pathophysiological significance of these observations.

Adult↗
PubMed1997

Multiple-dose mannitol reduces brain water content in a rat model of cortical infarction.

BACKGROUND AND PURPOSE: Repeated use of mannitol in the setting of ischemic infarction is a controversial and poorly defined therapeutic intervention. The purpose of this study was to examine the effects of repeated mannitol infusions on brain water content and tissue pressure in a well-defined rat model of focal ischemic stroke. METHODS: Mannitol infusions (0.5, 1.5, or 2.5 g/kg) were given by intravenous bolus 4 or 24 hours after 90-minute transient cortical ischemia in the territory of the right middle cerebral artery in rats and every 4 hours thereafter for a total of 24 hours. Fluid replacement was limited to 0.5 mL i.v. isotonic saline administered immediately after each mannitol dose. Control rats received 0.5 mL i.v. saline at the same intervals and were otherwise under ad libitum conditions. Water contents (percent H2O) of whole hemispheres and of cortical biopsies were measured with the wet-dry method, and blood samples were analyzed for plasma osmolality and chemistries. In a subgroup of rats, tissue pressure was also measured within the hemisphere ipsilateral to the infarct. RESULTS: Repeated mannitol infusions resulted in a dose-dependent increase in plasma osmolality and a dose-dependent decrease in the percent H2O of the ischemic middle cerebral artery cortex and ipsilateral hemisphere. In contrast, percent H2O of the contralateral cortex and hemisphere was significantly decreased only in the groups given the highest dose of mannitol (2.5 g/kg). Mannitol infusions at a dose of 1.5 g/kg begun 24 hours after reperfusion were also associated with a significant reduction of tissue pressure. CONCLUSIONS: In a rat model of ischemic cortical infarction, repeated mannitol infusions resulted primarily in a decrease in the percent H2O of the infarct and ipsilateral hemisphere, as well as decreased tissue pressure.

Animals↗
PubMed1997

Relationship between clot location and outcome after basilar artery thrombolysis.

PURPOSE: To identify factors that predict survival and good neurologic outcome in patients undergoing basilar artery thrombolysis. METHODS: Over a 42-month period, 20 of 22 consecutive patients with angiographic proof of basilar artery thrombosis were treated with local intraarterial urokinase. Brain CT scans, neurologic examinations, symptom duration, clot location, and degree of recanalization were analyzed retrospectively. RESULTS: Overall survival was 35% at 3 months. Survival in patients with only distal basilar clot was 71%, while survival in patients with proximal or midbasilar clot was only 15%. At 3 months, 29% of patients with distal basilar clot and 15% of patients with proximal or midbasilar clot had good neurologic outcomes (modified Rankin score of 0 to 2 and Barthel index of 95 to 100). Complete recanalization was achieved in 50% of patients; 60% of those survived and 30% had good neurologic outcomes. Of patients with less than complete recanalization, only 10% survived. Neither duration of symptoms before treatment (range, 1 to 79 hours), age (range, 12 to 83 years), nor neurologic status at the initiation of treatment (Glasgow Coma Scale score range, 3 to 15) predicted outcome. Pretreatment CT findings (positive or negative for related ischemic changes) did not predict outcome or hemorrhagic transformation. CONCLUSION: The single best predictor of survival after basilar thrombosis and intraarterial thrombolysis was distal clot location. Complete recanalization favored survival. Radiologically evident related infarctions, advanced age, delayed diagnosis, and poor pretreatment neurologic status did not predict poor outcome and therefore should not be considered absolute contraindications for intraarterial thrombolysis in patients with basilar artery thrombosis.

Adolescent↗
PubMed1996

Hospital resource utilization in the treatment of cerebral aneurysms.

The authors reviewed clinical and financial data for all patients treated for nontraumatic subarachnoid hemorrhage (SAH) and unruptured cerebral aneurysms at their institution between June 1993 and December 1994. This study sought to identify specific areas of high resource utilization that may be amenable to reduction of expenditures without compromising quality of care. Detailed hospital financial data were correlated with clinical grade and course. Areas of high resource use were identified based on patient charges and category-specific loaded hospital cost. Patients were divided into four groups: Group 1, surgically treated unruptured aneurysms (28 patients); Group 2, acute SAH (42 patients); Group 3, SAH with vasospasm (32 patients); and Group 4, SAH with negative angiogram (10 patients). Total cost per patient (mean +/- standard deviation in thousands of U.S. dollars) was highest for Group 3 (38.4 +/- 21.3; vs. Group 1, 12.7 +/- 8.8; Group 2, 22.6 +/- 20.9; and Group 4, 25.0 +/- 33.5) and correlated with hospital length of stay, Hunt and Hess grade, and Fisher grade. Areas of highest hospital cost were not always reflected in patient charges. The three areas of highest cost accounted for 48.5% of the total cost and were: 1) intensive care unit (ICU) room (Group 1, 2.5 +/- 3.5; Group 2, 7.0 +/- 9.2; Group 3, 11.0 +/- 7.8; and Group 4, 7.9 +/- 14.1); 2) arteriography (Group 1, 1.7 +/- 1.2; Group 2, 2.1 +/- 1.5; Group 3, 4.1 +/- 2.1; and Group 4, 2.2 +/- 0.7); and 3) ICU medicosurgical supplies (Group 1, 1.7 +/- 0.8; Group 2, 2.0 +/- 1.5; Group 3, 3.7 +/- 1.7; and Group 4, 2.0 +/- 3.0). It is concluded that cost containment strategies should be based on cost rather than charge and novel approaches will be required to reduce the cost of treating patients with SAH. Such approaches might include preventing vasospasm, reducing ICU stay, selective use of arteriography, and reducing the cost of supplies.

Aged↗
PubMed1995

Experimental therapies to improve delivery of oxygen and substrate in acute stroke.

The results of large-scale clinical trials of hemodilution therapy and vasodilators for acute stroke have been disappointing. However, interventions involving the manipulation of whole blood viscosity, blood oxygen-carrying capacity, cardiac output, and the resistance properties of cerebral vessels are viable therapeutic modalities currently being investigated. The central aim of all of these therapies is the timely improvement of perfusion and substrate delivery to ischemic brain regions. Better understanding of cerebrovascular flow regulation and the physiology of microvessels may give rise to more effective therapies. In the past, overemphasis on hematocrit reduction and cerebral vasodilators has obscured the potential risks of reducing blood oxygen content and vascular resistance during acute stroke and the importance of optimizing oxygen delivery by other means, in particular by cardiac output augmentation and manipulation of plasma properties. A broader approach to therapeutic strategies for acute stroke includes not only increasing cerebral blood flow, but also interventions that will create favorable changes in the humoral microenvironment and promote overall substrate delivery to the brain.

Acute Disease↗