title: Diabetic patients have an impaired cerebral vasodilatory response to hypercapnia under propofol anesthesia.
abstract: OBJECTIVE
  The purpose of this study was to examine the effects of diabetes mellitus and its severity on the cerebral vasodilatory response to hypercapnia.
  
  
  METHODS
  Thirty diabetic patients consecutively scheduled for elective major surgery were studied. After induction of anesthesia, a 2.5-MHz pulsed transcranial Doppler probe was attached to the patient's head at the right temporal window, and mean blood flow velocity of the middle cerebral artery (Vmca) was measured continuously. After the baseline Vmca, arterial blood gases, and cardiovascular hemodynamic values were measured, end-tidal CO2 was increased by reducing ventilatory frequency by 2 to 5 breaths per minute. Measurements were repeated when end-tidal CO2 increased and remained stable for 5 to 10 minutes.
  
  
  RESULTS
  Significant differences were observed in absolute and relative CO2 reactivity between the diabetes and control groups (absolute CO2 reactivity: control, 2.8+/-0.7; diabetes mellitus, 2.1+/-1.3; P<0.01; relative CO2 reactivity: control, 6.3+/-1.4; diabetes mellitus, 4.5+/-2.7; P<0.01, Mann-Whitney U test). Significant differences were also found between diabetic patients with retinopathy and those without retinopathy in absolute (P=0.002) and relative (P=0.002) CO2 reactivity, glycosylated hemoglobin (P=0.0034), and fasting blood sugar (P=0.01) (Scheffé's test, Mann-Whitney U test). There was an inverse correlation between absolute CO2 reactivity and glycosylated hemoglobin (r=0.69, P<0.001).
  
  
  CONCLUSIONS
  Insulin-dependent diabetic patients have an impaired vasodilatory response to hypercapnia compared with that of the control group, and the present findings suggest that their degree of impairment is related to the severity of diabetes mellitus.
authors.affiliation: Intensive Care Medicine, Gunma University School of Medicine, 3-39-15 Showa-Machi, Maebashi, Gunma 371-8511, Japan. kadoi@med.gunma-u.ac.jp
authors.forename: Yuji
authors.initials: Y
authors.lastname: Kadoi
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Hinohara
authors.forename: Fumio
authors.initials: F
authors.lastname: Kunimoto
authors.forename: Shigeru
authors.initials: S
authors.lastname: Saito
authors.forename: Masanobu
authors.initials: M
authors.lastname: Ide
authors.forename: Haruhiko
authors.initials: H
authors.lastname: Hiraoka
authors.forename: Fuminori
authors.initials: F
authors.lastname: Kawahara
authors.forename: Fumio
authors.initials: F
authors.lastname: Goto
mesh_terms: D000758:Anesthesia / Q000009:adverse effects; D001783:Blood Flow Velocity / Q000187:drug effects; D001784:Blood Gas Analysis; D001921:Brain / Q000098:blood supply; D002245:Carbon Dioxide / Q000097:blood / Q000502:physiology; D002560:Cerebrovascular Circulation / Q000187:drug effects / Q000502:physiology; D048909:Diabetes Complications; D003920:Diabetes Mellitus / Q000503:physiopathology*; D003930:Diabetic Retinopathy / Q000150:complications / Q000503:physiopathology; D017558:Elective Surgical Procedures / Q000009:adverse effects; D005260:Female; D006442:Glycated Hemoglobin / Q000032:analysis; D006801:Humans; D006935:Hypercapnia / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D020768:Middle Cerebral Artery / Q000000981:diagnostic imaging / Q000187:drug effects / Q000503:physiopathology; D015742:Propofol / Q000008:administration & dosage*; D011659:Pulmonary Gas Exchange; D012016:Reference Values; D017585:Ultrasonography, Doppler, Transcranial; D014664:Vasodilation / Q000502:physiology
chemical_list: D002245:Carbon Dioxide; D006442:Glycated Hemoglobin; D015742:Propofol