Comparison of CapiFlow and frame by frame analysis for the assessment of capillary red blood cell velocity.

CapiFlow (CF), a new fully computerized system for the measurement of capillary blood velocity (CBV) was compared to manual frame by frame analysis (a) in a model system, and (b) in finger nailfold capillaries recorded on video tape. In the model the overall agreement between the two methods was very good (figure 1), with no significant differences being noted between the two sets of results and the calculated velocities. However, when comparing frame by frame and CapiFlow directly, CapiFlow read on average 4.50 +/- 5.21% higher than frame by frame analysis (figure 2). The in vivo results obtained by the two methods showed similar dynamic changes although some differences between the overall mean CBVs were noted (capillary 1, manual 0.13 +/- 0.59 mm s-1 versus CF 0.12 +/- 0.02 mm s-1, (mean +/- SD), p = 0.354; capillary 2, manual 0.66 +/- 0.23 mm s-1 versus CF 0.47 +/- 0.09 mm s-1, p < 0.001; capillary 3, manual 2.53 +/- 0.73 mm s-1 versus CF 2.35 +/- 0.34 mm s-1, p = 0.062). Further analyses established the optimum settings of delta limit and cross correlation. Investigations into the effects of changes in window size, window distance or video settings on CBV results obtained by CapiFlow, indicated that only settings radically different from the optimum had a significant effect on the results obtained.

[1]  A. Shore,et al.  The effect of acetylcholine on finger capillary pressure and capillary flow in healthy volunteers. , 1996, The Journal of physiology.

[2]  B Rosen,et al.  On-line measurement of microvascular diameter and red blood cell velocity by a line-scan CCD image sensor. , 1993, Microvascular research.

[3]  M Anliker,et al.  Evaluation of an on-line videodensitometric measurement of the red blood cell velocity in the capillaries of the human nailfold , 1975, Biomedizinische Technik. Biomedical engineering.

[4]  H Wayland,et al.  Erythrocyte velocity measurement in microvessels by a two-slit photometric method. , 1967, Journal of applied physiology.

[5]  W Siegenthaler,et al.  Red blood cell velocity in nailfold capillaries of man measured by a television microscopy technique. , 1974, Microvascular research.

[6]  F. Mahler,et al.  Evaluation and clinical application of the flying spot method in clinical nailfold capillary TV-microscopy. , 1987, International journal of microcirculation, clinical and experimental.

[7]  A. Beckett,et al.  AKUFO AND IBARAPA. , 1965, Lancet.

[8]  M Intaglietta,et al.  Capillary flow velocity measurements in vivo and in situ by television methods. , 1975, Microvascular research.

[9]  D. Altman,et al.  STATISTICAL METHODS FOR ASSESSING AGREEMENT BETWEEN TWO METHODS OF CLINICAL MEASUREMENT , 1986, The Lancet.

[10]  M Intaglietta,et al.  Capillary red blood cell velocity measurements in human nailfold by videodensitometric method. , 1975, Microvascular research.