Establishment of the Cardio-Ankle Vascular Index in Patients With Obstructive Sleep Apnea
ABSTRACT An arterial stiffness parameter, the cardio-ankle vascular index (CAVI), has been developed. CAVI is adjusted for BP and can be used to measure arterial stiffness with little influence of BP. The purpose of this study was to evaluate the reproducibility, validity, and clinical usefulness of CAVI among patients with obstructive sleep apnea (OSA), who often have elevated BP during measurement.
Overall, 543 consecutive patients with OSA were studied. CAVI was automatically calculated from the pulse volume record, BP, and the vascular length from the heart to the ankle. First, CAVI was measured three times on different days in 25 patients to evaluate its reproducibility. Second, the correlation between CAVI and BP was assessed. Third, patients were classified into two groups (mild OSA or moderate-to-severe OSA), and the CAVIs of these groups were compared. Fourth, the correlation between CAVI and carotid intima-media thickness (IMT) was also assessed in 74 patients.
The mean coefficient of variation was 2.8. CAVI demonstrated weak or no correlations with BP (with systolic BP, r = 0.184; with diastolic BP, r = 0.223). Patients with moderate-to-severe OSA (n = 469) had a significantly greater CAVI than patients with mild OSA (p = 0.034). CAVI was positively correlated with IMT (r = 0.487).
The measurement of CAVI demonstrated good reproducibility and was not affected by the BP during measurement. Additionally, CAVI was positively correlated with another arteriosclerosis indicator. CAVI was higher in patients with more severe OSA and is regarded as a clinically useful index for the progression of vascular damage.
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- "We have previously reported that the CAVI measures arterial stiffness independent of blood pressure6. Increased arterial stiffness has been reported to be complicated by metabolic syndrome7, sleep apnea syndrome8 and smoking9. However, a detailed relationship between hyperglycemia and arterial stiffness has not been fully clarified. "
ABSTRACT: AbstractAims/IntroductionAlthough arteriosclerotic diseases have been reported to be frequently complicated by diabetes mellitus (DM), a detailed relationship between hyperglycemia and arterial stiffness has not been fully clarified. We investigated the influence of hyperglycemia on arterial stiffness using the cardio‐ankle vascular index (CAVI), which is a new method for estimating arterial stiffness.Materials and Methods CAVI values of 52 early‐staged DM patients (duration <5 years, no microangiopathies) were compared with those of 43 age‐matched non‐diabetic (NDM) subjects. The association between CAVI and clinical background factors was evaluated. The effect of glycemic improvement on CAVI was examined in 36 DM patients who were hospitalized for 2 weeks to treat hyperglycemia. CAVI and clinical parameters were measured twice during hospitalization and again after 8 weeks. Additionally, we measured CAVI before and 2 h after breakfast in five DM and five NDM subjects.ResultsThe CAVI of DM patients was significantly higher than that of NDM subjects. Multiple regression analysis showed that neither hypertension, obesity nor dyslipidemia, but aging and hemoglobin A1c (HbA1c) were significantly related to CAVI elevation. The CAVI, HbA1c and total cholesterol (TC) had significantly improved. Improvement of CAVI was significantly associated with HbA1c improvement. In contrast, no significant association was observed between the improvements of TC and CAVI. CAVI values before and after breakfast did not change significantly.Conclusions CAVI elevation seems to be a sensitive arteriosclerotic marker, which is closely associated with hyperglycemia and improved by glycemic control.01/2013; 4(1):82-7. DOI:10.1111/j.2040-1124.2012.00229.x
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ABSTRACT: A three-layer adaptive clustering neural net is described for distortion-invariant multiclass object recognition in difficult problems requiring piecewise nonlinear discriminant surfaces. The number of hidden-layer neurons is determined by an organized procedure (several neurons are used per class as prototypes of each class). These are chosen by clustering techniques. The vector description of each prototype in the multidimensional input feature space specifies a set of linear discriminant functions that are the initial input to the hidden-layer weights used. These weights are then refined by a neural net algorithm using conjugate gradient techniques to produce the final weights. A neural net (NN) that marries pattern-recognition and NN techniques is thus obtained. Various multiclass distortion-invariant classification results are presentedNeural Networks, 1990., 1990 IJCNN International Joint Conference on; 07/1990
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ABSTRACT: During the first 6 months of the year 2009 have been published numerous articles about sleep apnea-hypoapnea syndrome (SAHS). These articles reaffirm different aspects published previously and gives new light on other areas less explored. Thus, these publications reinforce the evidence that SAHS is associated with increased inflammatory mechanisms and that CPAP therapy decrease inflammatory mechanisms. Also, these articles strengthens the association between this patology and morbidity-mortality, especially cardio-cerebrovascular disease. The dimension that reaches sleep apnea does necessary to achieve an appropriate population screening, a correct treatment and close follow-up, in order to obtain better control of these patients and fewer complications.01/2010; 13(1):23–28. DOI:10.1016/S1576-9895(10)70030-8