Study On Changes Of Cerebral Blood Flow Velocity During Head-up Tilt In Patients With Diabetes Mellitus Under General Anesthesia

[Objective]To observe changes of cerebral blood flow velocity in patients with diabetes mellitus who underwent general anesthesia after 45°head-up tilt.[Methods]60 patients were recruited who underwent general anesthesia in this study, aging 40-60 years,ASAâ… -â…¡.Group A:20 patients age matched controls.Group B:20 type 2 diabetes mellitus patients with autonomic neuropathy;Group C:20 type 2 diabetes mellitus patients without autonomic neuropathy.They are all diagnosed more than 1 year ago.They were divided into two groups according to R-R interval variation and sympathetic skin response test.All patients were intubated after general anesthesia, anesthesia was maintained with 1%sevoflurane and maintained EtCO₂ at 35mmHg. Mean arterial pressures,heart rates and cerebral middle artery blood flow velocities were recorded at supine position(T₀ ) and 1.5min(T₁),3.5min(T₂),5.5min(T₃) after the patients were raised head-up 45°position.[Results]No siganificant differences were found about MAP HR and MBFV at T₀ among three groups(P＞0.05).MAP was decreasd siganificantly at T₁ in Group C(P＜0.05).Mean blood flow velocities were decreased 9.5%,10.0%and 15.4% respectly and then rose up slowly.Mean blood flow velocities of diabetic patients with autonomic neuropathy were found more decreased at 1.5min after the patients were raised head-up 45°position.[Discussion]Celebral autoregulatioon is the intrinsic ability of the brain to maintain constant cerebral blood flow during changes of cerebral perfusion pressure.Autonomic neuropathy due to diabetes mellitus affects cerebral autoregulation.