Beneficial Effect of Prolonged Administration of Albumin on Ischemic Cerebral Edema and Infarction after Occlusion of Middle Cerebral Artery in Rats

Albumin therapy for acute ischemic stroke: a meta-analysis

Human serum albumin has shown remarkable efficacy in rodent models of ischemic stroke, while results from relevant clinical research on albumin therapy remain controversial. We conducted a meta-analysis of published studies to quantitatively analyze the neurofunctional outcomes of patients with ischemic stroke treated with albumin. PubMed, Embase, and Cochrane Library were searched in July 2020. A total of four studies and 1611 patients were included. The aggregated results indicated that there were 635 patients with good neurological outcomes, among which 321 patients were in the albumin group (39.8%) and 314 patients in the control group (39.1%), showing no statistically significant difference between the albumin and control groups (OR = 1.04, 95% CI 0.85-1.27). The results suggest that albumin therapy at the acute stage of ischemic stroke has no beneficial effect on the long-term neurological function of patients with ischemic stroke. Considering pulmonary edema and other complications are more likely to occur in such patients after albumin infusion, the administration of albumin therapy for acute ischemic stroke should be done with utmost caution.

Aspects on the Physiological and Biochemical Foundations of Neurocritical Care

Neurocritical care (NCC) is a branch of intensive care medicine characterized by specific physiological and biochemical monitoring techniques necessary for identifying cerebral adverse events and for evaluating specific therapies. Information is primarily obtained from physiological variables related to intracranial pressure (ICP) and cerebral blood flow (CBF) and from physiological and biochemical variables related to cerebral energy metabolism. Non-surgical therapies developed for treating increased ICP are based on knowledge regarding transport of water across the intact and injured blood-brain barrier (BBB) and the regulation of CBF. Brain volume is strictly controlled as the BBB permeability to crystalloids is very low restricting net transport of water across the capillary wall. Cerebral pressure autoregulation prevents changes in intracranial blood volume and intracapillary hydrostatic pressure at variations in arterial blood pressure. Information regarding cerebral oxidative metabolism is obtained from measurements of brain tissue oxygen tension (PbtO2) and biochemical data obtained from intracerebral microdialysis. As interstitial lactate/pyruvate (LP) ratio instantaneously reflects shifts in intracellular cytoplasmatic redox state, it is an important indicator of compromised cerebral oxidative metabolism. The combined information obtained from PbtO2, LP ratio, and the pattern of biochemical variables reveals whether impaired oxidative metabolism is due to insufficient perfusion (ischemia) or mitochondrial dysfunction. Intracerebral microdialysis and PbtO2 give information from a very small volume of tissue. Accordingly, clinical interpretation of the data must be based on information of the probe location in relation to focal brain damage. Attempts to evaluate global cerebral energy state from microdialysis of intraventricular fluid and from the LP ratio of the draining venous blood have recently been presented. To be of clinical relevance, the information from all monitoring techniques should be presented bedside online. Accordingly, in the future, the chemical variables obtained from microdialysis will probably be analyzed by biochemical sensors.

Associations between cerebrospinal fluid protein concentrations, serum albumin concentrations and intracranial pressure in neurotrauma and intracranial haemorrhage

Recent evidence suggests that using intravenous isotonic albumin solution for haemodynamic resuscitation in neurotrauma is associated with adverse outcomes. This study assessed the correlations between cerebrospinal fluid protein concentrations, serum albumin concentrations and intracranial pressure in a cohort of neurosurgical patients. After obtaining ethics committee approval, correlations between concomitant cerebrospinal fluid protein concentrations, serum albumin concentrations and the mean daily intracranial pressure of 63 consecutive neurosurgical patients, grouped as neurotrauma or intracranial haemorrhage, admitted between 1 January and 31 December 2007, were assessed. The mean daily intracranial pressure was significantly associated with cerebrospinal fluid protein concentrations (Spearman correlation coefficient [SCC] = 0.496, P = 0.001), white cell counts (SCC = 0.359, P = 0.001), red cell counts (SCC = 0.399, P = .0O01) and serum albumin concentrations (SCC = 0.431, P = 0.001) in patients with neurotrauma (n=23). Cerebrospinal fluid protein concentrations were also significantly associated with concomitant serum albumin concentrations (SCC = 0.393, P = 0.001) in these patients. In patients with intracranial haemorrhage (n=40), the mean daily intracranial pressure was only significantly associated with cerebrospinal fluid white cell and red cell counts but not cerebrospinal fluid protein and serum albumin concentrations. In summary, intracranial pressure is correlated with cerebrospinal fluid protein and serum albumin concentrations in patients with severe neurotrauma, and these suggest that blood-brain barrier may not be completely intact after severe neurotrauma.

Serum albumin level as a predictor of outcome in traumatic brain injury: potential for treatment

BACKGROUND

Serum albumin level is correlated with outcome in various clinical situations. Albumin has multiple physiologic properties that could be beneficial in brain injury. The Lund therapy for elevated intracranial pressure uses albumin as part of its protocol and demonstrates favorable outcome. We sought to find out if albumin is associated with outcome after traumatic brain injury to justify conducting a randomized trial.

METHODS

A retrospective study of traumatic brain injury patients was conducted. Characteristics known to influence outcome were included in a multiple logistic regression model to analyze predictors of poor outcome at 6 months.

RESULTS

Data were available for 138 patients. The majority of patients (65%) had a severe injury (Glasgow Coma Scale score <9). Seventy percent of patients had a favorable outcome. Albumin levels decrease considerably from normal values in the first few days after injury irrespective of outcome. Albumin remained <25 g/L for a longer period of time in patient with an unfavorable outcome (6 days vs. 3 days, p = 0.012). Multiple logistic regression analysis identified albumin levels, age, Glasgow Coma Scale score at admission, and Injury Severity Score as predictors of poor outcome.

CONCLUSION

Serum albumin level seems to be an independent predictor of poor outcome. The model also identified classic predictors of poor outcome that tends to strengthen its adequacy. Because albumin level is the only modifiable factor influencing outcome, it seems justified to carry out a randomized trial of the use of albumin in the treatment of brain injury.

Volume-targeted therapy of increased intracranial pressure: the Lund concept unifies surgical and non-surgical treatments

Opinions differ widely on the various treatment protocols for sustained increase in intracranial pressure (ICP). This review focuses on the physiological volume regulation of the intracranial compartments. Based on these mechanisms we describe a protocol called 'volume-targeted' ('Lund concept') for treatment of increased ICP. The driving force for transcapillary fluid exchange is determined by the balance between effective transcapillary hydrostatic and osmotic pressures. Fluid exchange across the intact blood-brain barrier (BBB) is counteracted by the low permeability to crystalloids (mainly Na+ and Cl-) combined with the high osmotic pressure (5500 mmHg) on both sides of the BBB. This contrasts to most other capillary regions where the osmotic pressure is mainly derived from the plasma proteins (approximately 25 mmHg). Accordingly, the level of the cerebral perfusion pressure (CPP) is of less importance under physiological conditions. In addition cerebral intracapillary hydrostatic pressure (and cerebral blood flow) is physiologically tightly autoregulated, and variations in systemic blood pressure are generally not transmitted to these capillaries. If the BBB is disrupted, transcapillary water transport will be determined by the differences in hydrostatic and colloid osmotic pressure between the intra- and extracapillary compartments. Under these pathological conditions, pressure autoregulation of cerebral blood flow is likely to be impaired and intracapillary hydrostatic pressure will depend on variations in systemic blood pressure. The volume-targeted 'Lund concept' can be summarized under four headings: (1) Reduction of stress response and cerebral energy metabolism; (2) reduction of capillary hydrostatic pressure; (3) maintenance of colloid osmotic pressure and control of fluid balance; and (4) reduction of cerebral blood volume. The efficacy of the protocol has been evaluated in experimental and clinical studies regarding the physiological and biochemical (utilizing intracerebral microdialysis) effects, and the clinical experiences have been favorable.

Effects of AE0047 on cerebral ischaemia and oedema after middle cerebral artery occlusion in cats

1. AE0047 is a new dihydropyridine calcium antagonist with protective effects against cerebral ischaemia and the occurrence of stroke in several animal models. 2. In the present study we investigated whether AE0047 would improve the reduced cerebral blood flow (CBF) and oedema formation in cats subjected to middle cerebral artery (MCA) occlusion and compared it for efficacy with other dihydropyridine calcium antagonists with different moieties, such as nilvadipine and nicardipine. 3. Middle cerebral artery occlusion reduced local CBF (ICBF), as measured by the hydrogen clearance method, while dry weight measurement showed that water content in the cortical tissues surrounding each ICBF measurement electrode had increased after 4 h ischaemia. 4. Both AE0047 (10 micrograms/kg) and nilvadipine (30 micrograms/kg), given intravenously 20 min after MCA occlusion, produced an approximate 10% hypotensive response and significantly increased ICBF in severely and moderately ischaemic regions, grouped according to the initial reduced flow values. However, nicardipine (5 micrograms/kg bolus followed by infusion of 3 micrograms/kg per min for 60 min) failed to mitigate the reduction in ICBF despite an increase in the ICBF of the contralateral cortex. In addition, AE0047 tended to prevent an increase in cortical water content in severely ischaemic regions, whereas water content in both nilvadipine- and nicardipine-treated groups tended to increase. 5. These results suggest that dihydropyridine calcium antagonists act differently on cerebral ischaemia and oedema formation in a manner dependent on their side-chain structures and that AE0047 effectively attenuates ischaemic brain damage without aggravating oedema.

Effects of the calcium antagonist AE0047 on the development of neurological deficit and infarction after middle cerebral artery occlusion in stroke-prone spontaneously hypertensive rats

AE0047 [4-(4-benzhydrylpiperazino)phenethyl methyl 1,4-dihydro-2,6-dimethyl-4-(3-nitrophenyl)-3,5-pyridine dicarboxylate dihydrochloride] is a new dihydropyridine calcium antagonist with protective effects against cerebral ischaemia and the occurrence of stroke in several animal models. We investigated the effects of AE0047 on focal ischaemia induced by middle cerebral artery occlusion in stroke-prone spontaneously hypertensive rats. AE0047 at a dose causing 20 or 40% systemic hypotension (1 or 3 mg kg-1) was given orally twice, 15 min and 24 h after occlusion. The neurological status of animals was investigated 2, 24 and 48 h after occlusion. Infarct area of brain was measured 48 h after occlusion. Middle cerebral artery occlusion resulted in the progressive deterioration of neurological status and large infarction in middle cerebral artery territories with 40% mortality. AE0047 dose-dependently attenuated the deterioration of neurological status, and reduced mortality to 0 or 10%. AE0047 significantly reduced infarct size and left/right hemispheric area ratio, an index of brain swelling. These results suggest that AE0047 has the ability to ameliorate ischaemic cerebral stroke in hypertensive patients.