The Determination and Evaluation of Capillary Resistance—A Review of Methodology

In view of the uncertainty and inadequacy still prevailing in the routine determination and interpretation of capillary resistance, the problem has been analyzed in the hope of contributing to a much needed improvement.

(1) The pressure and suction methods have been compared and a good correlation found. A study of the mechanisms involved reveals that both methods rest upon a common underlying mechanism. The suction method is in reality a miniature pressure method.

(2) Scrutiny of the merits and shortcomings of the two methods leads to the conclusion that the pressure method can serve only for crude estimations of capillary resistance. Detailed clinical studies of capillary resistance requiring repeated accurate measurements at short intervals, as well as experimental animal studies, necessitate the suction method as the obvious method of choice.

(3) The three main causes of the present undesirable situation in this field are discussed: lack of standardization; inadequate realization of the pitfalls of testing; and erroneous interpretation of findings.