Objective:To investigate the effect of hypertonic sodium chloride hydroxylethyl starch 40（HH40）infused intravenously for volume expansion before controlled hypotension on electrolytes and acid-base balance in intracranial aneurysm surgery.Methods:Forty ASAⅠorⅡpatients aged 22～67 years

weighing 46～72 kg

scheduled for intracranial aneurysm surgery were randomly allocated to one of two groups:HH40 group（n=20）and control group（n=20）.Anesthesia was induced with midazolam 0.1～0.15 mg/kg

fentanyl 4～5μg/kg and vecuronium 0.1～0.2 mg/kg.The patients were mechanically ventilated after tracheal intubation and PetCO

2

were maintained 25～30 mmHg by modulating V

T

and RR.Anesthesia was maintained by propofol and remifentanil pumped intravenously and inhalation of isoflurane 0.5～2 vol%.Before segregaton of the aneurysm

nitroprusside sodium was pumped with 0.3～0.8μg/kg/min intravenously to induce hypotension.The left femoral artery was cannulated to collect arterial blood gases and measure mean arterial pressure（MAP）.A central venous catheter was placed via right internal jugular vein to measure central venous pressure（CVP）and collect venous blood samples.During the first 30 minutes after meninx fibrosa incision

HH40 group was infused with HH40 250 ml whereas the control group with isotonic hydroxylethyl starch 500 ml.Normal saline solution was used in both groups in the other time of the surgery.HR

MAP

CVP

arterial blood gases

electrolytes

blood sugar and hemorheology were measured before surgical incision（T

0

）

before meninx fibrosa incision（T

1

）

30 minutes after meninx fibrosa incision（T

2

）

at the beginning of controlled hypotention（T

3

）

just after the clipping of the aneurysm（T

4

）

at the end of the surgery（T

5

）

1h after the surgery（T

6

）

2 h after the surgery（T

7

）

Crystalloid osmolality was calculated by the equation:OSM（mmol/L）=2（Na

+

mmol/L +K

+

mmol/L）+blood sugar（mmol/L）at each time point as mentioned above. Blood loss

infused solution volume and urinary volume were measured at the end of the surgery.The patients were followed-up for one week after the operation to observe the neurological complication.Results:Each group excluded one patient for the rupture of the aneurysm and use of mannitol.Compared with T

0

MAP in both groups and CVP in the control group were decreased at T

4

while CVP in both groups were increased significantly during T

5-7

.CVP in HH40 group was higher than that in the control group during T

3～5

.Plasma sodium concentration and crystal osmolality in HH40 group were increased significantly in T

2

compared with T

0

and were higher thanthose in control group.Blood sugar was increased during T

3～8

in both groups.Blood viscosity in both groups were decreased during T

3～6

as compared with T

0

and the data was lower in HH40 group than those in control group during T

3～4

.Conclusion:HH40 250 ml can be safely used in intracranial aneurysm surgery for its benefits in volume expansion and organ perfusion by decreasing the blood viscosity without disordering the electrolytes and acid-base balance.