Effect of head-up tilt on cerebral blood flow velocity during general anesthesla in patients with diabetic neuropathy

Objective To investigate the effect of head-up tilt on cerebral blood flow velocity during general anesthesia in patients with diabetic neuropathy.Methods Sixty ASA Ⅰ - Ⅱ patients of both sexes aged 40-60 yr weighing 52-70 kg undergoing general anesthesia were divided into 3 groups according to diseases complicated with diabetes situation ( n =20 each):group Ⅰ normal control the patients did not have diabetes mellitus; group Ⅱ type Ⅱ diabetics without neuropathy and group Ⅲ Ⅱ diabetics with neuropathy.Anesthesia was induced with propofol 2 mg/kg,fentanyl 3 μg/kg and vecuronium 0.1 mg/kg and maintained with 1％ sevoflurane.The patients were intubated and mechanically ventilated.PErCO2 was maintained at 35-45 mm Hg.Transcranial doppler (TCD)was used to measure middle cerebral artery blood flow velocity (MBFV).MAP and MBFV were measured and recorded in supine position (baseline) and at 1.5,3.5 and 5.5 min of 45° head-up tilt.Results The 3 groups were comparable with respect to age,body weight,height and M/F sex ratio.MAP and MBFV significantly decreased at 45° head-up tilt as compared with the baseline in all the 3 groups.There was no significant difference in MAP and MBFV among the 3 groups.Conclusion Cerebral blood flow velocity decreases when the patients are tilted 45° head-up during general anesthesia in both diabetics with and without neuropathy,but there is no significant difference between the 2 groups. Key words: Posture;  Diabetes mellitus;  Diabetic neuropathies;  Anesthesia, general;  Blood flow velocity;  Brain