Todd MM, Tommasino C, Moore S: Cerebral effects of isovolemic hemodilution with a hypertonic saline solution
In view of a growing interest in the resuscitative use of hypertonic saline solutions, the authors have examined the cerebral effects of isovolemic hemodilution carried out over 1 hour (hematocrit decreased from 40% to 20%, stable arterial and right arterial pressures), using a hypertonic lactated Ringer's solution (HT-LR: Na+ 252 mEq/liter, osmolality 480 mOsm/liter). Experiments were carried out in anesthetized ventilated rabbits. Measured variables included cerebral blood flow (using the H2 clearance method), intracranial pressure (ICP), the electroencephalogram, spinal cord and skeletal muscle water content (%H2O), and the specific gravity of small (10- to 30-mg) tissue samples taken from different areas of the left hemisphere (including the cortex, thalamus, internal capsule, and hippocampus). The changes produced by HT-LR were compared with those seen in both undiluted control animals and in rabbits hemodiluted with normal saline (Na+ 155 mEq/liter, osmolality 310 mOsm/liter). The results demonstrate that hemodilution with HT-LR leads to the expected increases in serum Na+ and osmolality (158 +/- 6 mEq/liter and 320 +/- 5 mOsm/kg, respectively, mean +/- standard deviation) and that these were accompanied by reductions in the %H2O of all cerebral and extracerebral tissues, increases in the specific gravity of all tissue regions studied, and a decrease in ICP (1.9 +/- 0.7 mm Hg). By contrast, rabbits with hemodilution by normal saline showed no changes in either %H2O or specific gravity, but had significant increases in ICP (3.3 +/- 1.3 mm Hg). Cerebral blood flow increased in all animals hemodiluted with either HT-LR or normal saline by a combined average of +29 ml/100 gm/min. Although these studies were performed in neurologically normal animals, the combination of cerebral changes seen with HT-LR (cerebral dehydration, less peripheral edema, decreased ICP but with increased cerebral blood flow) suggests that this approach may have some advantages over the use of isotonic fluids, and may have some utility in the resuscitation of head-injured patients.
Available from: e-flanc.net
- "Certain adverse effects of this method were observed in some of these studies  . The purpose of the present study, therefore, was to evaluate more extensively the efficacy and safety of HS in the treatment of patients with IH. "
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ABSTRACT: The present study was undertaken to evaluate the efficacy and safety of hypertonic saline (HS) in the treatment of intracranial hypertension after severe head injury.
This prospective, observational study was performed in an 11-bed neurosurgery intensive care unit of a teaching hospital. From February 2002 to September 2004, 18 severely head-injured patients with elevated intracranial pressure (ICP) and Glasgow Coma Scale scores of 5 to 8 (mean, 5.9 +/- 1.2) were admitted to the unit and treated according to a standard protocol. One dose per day of 3% saline was administered by rapid infusion (300 mL/20 min) when ICP values exceeded 20 mm Hg. After infusion, cerebral blood flow, ICP, blood pressure, end-tidal carbon dioxide, and heart rate were monitored continuously for 60 minutes and recorded. Serum osmolarity, sodium, potassium, chloride, arterial carbon dioxide pressure, arterial oxygen pressure, hemoglobin, lactic acid, and pH were measured immediately before infusion (zero time) and 20 and 60 minutes after infusion. Mean arterial pressure, cerebral perfusion pressure (CPP), mean flow velocity (MFV), and pulsatility index (PI) were also recorded and analyzed.
Intracranial pressure fell immediately after initiation of infusion with further significant decreases observed at 20 and 60 minutes (30.4 +/- 8.5, 24.3 +/- 7.4, and 23.8 +/- 8.3 mm Hg, respectively; P < .01). At these respective times CPP increased significantly (78.7 +/- 8.7, 83.2 +/- 7.8, and 87.2 +/- 12.8 mm Hg), PI dropped rapidly (1.51 +/- 0.42, 1.38 +/- 0.32, and 1.34 +/- 0.33) and MFV increased (66.26 +/- 25.91, 71.92 +/- 28.13, and 68.74 +/- 28.44). Serum sodium increased from 141.3 +/- 7.2 to 146.3 +/- 7.2 mmol/L after 20 minutes and returned to 144.3 +/- 7.36 mmol/L at 60 minutes. Potassium concentrations decreased significantly from 3.9 +/- 0.39 to 3.55 +/- 0.35 mmol/L after 20 minutes (P < .01). Lactic acid values at 0, 20, and 60 minutes were 1.6 +/- 0.5, 1.47 +/- 0.48, and 1.38 +/- 0.53 mmol/L, respectively (P < .01).
Rapid infusion of single dose daily of HS is a safe alternative for the treatment of elevated ICP in severe head injury. Further evaluations of long-term consequences and complications and of maximal tolerance to this treatment are required.
Available from: Concezione Tommasino
- "However, the occurrence of hyponatremia after acute spinal cord injury stresses the importance of appropriate fluid management in these patients, mostly to prevent the consequences of reduced plasma osmolality, which might exacerbate spinal cord edema. Laboratory researches have demonstrated that hypertonic saline decreases spinal cord water content , and may provide protection after mechanical injury . "
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ABSTRACT: Few human data exist concerning the impact of fluid administration on brain pathophysiology. Those factors that influence water movement into the brain are examined, in order to provide reasonable recommendations for peri-operative fluid management in the patients with brain pathology.
Available from: nih.gov
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ABSTRACT: Resuscitation from hemorrhagic shock by infusion of isotonic (normal) saline (NS) is accompanied by a transient elevation in intracranial pressure (ICP), although cerebral edema, as measured by brain weights at 24 hours, is prevented by adequate volume resuscitation. The transient increase in ICP is not observed during hypertonic saline (HS) resuscitation. The effect of colloid resuscitation on ICP is unknown. Beagles were anesthetized, intubated, and ventilated, maintaining pCO2 between 30-45 torr. Femoral artery, pulmonary artery, and urethral catheters were positioned. ICP was measured with a subarachnoid bolt. Forty per cent of the dog's blood volume was shed and the shock state maintained for 1 hour. Resuscitation was done with shed blood and a volume of either NS (n = 5), 3% HS (n = 5), or 10% dextran-40 (D-40, n = 5) equal to the amount of shed blood. Intravascular volume was then maintained with NS. ICP fell from baseline values (4.7 +/- 3.13 mmHg) during the shock state and increased greatly during initial fluid resuscitation in NS and D-40 groups, to 16.0 +/- 5.83 mmHg and 16.2 +/- 2.68 mmHg, respectively. ICP returned to baseline values of 3.0 +/- 1.73 mmHg in the HS group with initial resuscitation and remained at baseline values throughout resuscitation. NS and D-40 ICP were greater than HS ICP at 1 hour (p less than .001) and 2 hours (p less than .05) after resuscitation. These results demonstrate that NS or colloid resuscitation from hemorrhagic shock elevates ICP and that HS prevents elevated ICP.
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