title: Combination of cardiorespiratory reflex parameters and heart rate variability power spectrum analysis for early diagnosis of diabetic cardiac autonomic neuropathy.
abstract: OBJECTIVE
  The study objective was to compare cardiorespiratory reflex (CR-R) parameters and heart rate variability power spectrum (HRV-PS) analysis in the diagnosis of cardiac autonomic neuropathy (CAN) in diabetic patients.
  
  
  METHODS
  Four CR-R tests (Valsalva manoeuvre, deep breathing, and two successive 5-minute periods with the subject supine and standing, respectively) were performed in 399 diabetic patients (58.6% male, median age: 51 years) and 105 healthy controls (40% male, median age: 34 years). Patients with two or more abnormal CR-R parameters were classified as CAN+, while those with only one abnormal CR-R parameter were considered CAN 'borderline'. HRV-PS was performed in all study participants.
  
  
  RESULTS
  The low-frequency (LF) area with the patient standing was reduced in CAN+ diabetics (median 35.6 normalized units [nu], n=31), in CAN 'borderline' diabetics (median 64.3nu, n=70) and even in diabetics without CAN (median 89.4nu, n=298) versus control subjects (median 93.7nu; P<0.001, P<0.001 and P<0.05, respectively). Adding the abnormal (<2.5 nu) LF area to the diagnostic criteria in CAN 'borderline' patients caused 11 (15.7%) patients to be considered CAN+.
  
  
  CONCLUSIONS
  Combining abnormal CR-R parameters (I - E and I/E the most specific) with HRV-PS (particularly the LF area with the subject standing) allowed diagnosis of diabetic CAN at an earlier stage.
authors: University Department of Medicine and Service of Endocrinology and Nutrition, University Hospital of Santiago, USC, Santiago de Compostela, Spain. jose.cabezas@usc.es
authors: J
authors: J
authors: Cabezas-Cerrato
authors: A
authors: A
authors: Gonzalez-Quintela
authors: M
authors: M
authors: Perez-Rodriguez
authors: A
authors: A
authors: Calle
authors: E
authors: E
authors: Faure-Noguera
authors: J A
authors: JA
authors: Vazquez-Garcia
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging; D016009:Chi-Square Distribution; D003920:Diabetes Mellitus / Q000503:physiopathology; D003929:Diabetic Neuropathies / Q000175:diagnosis* / Q000503:physiopathology; D042241:Early Diagnosis; D004562:Electrocardiography / Q000379:methods; D005260:Female; D005583:Fourier Analysis; D006334:Heart Function Tests; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012018:Reflex / Q000502:physiology*; D012129:Respiratory Function Tests; D012307:Risk Factors; D012815:Signal Processing, Computer-Assisted; D018709:Statistics, Nonparametric; D016683:Supine Position