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HANDBOOK OF PHYSIOLOGY 



CIRCULATION II 



parts. In the first part the leg is elevated above the 

 body, the veins are emptied, and a tourniquet is 

 applied over the upper thigh tightly enough to occlude 

 the superficial but not the deep veins. The patient 

 then stands. If the superficial veins fill quickly (in 

 less than 30 sec) then the valves of the deep to super- 

 ficial communicating veins are incompetent. The 

 second part of the test is similar except that the 

 tourniquet is removed at the moment the patient 

 stands. If the superficial veins fill immediately in a 

 retrograde fashion, then the saphenous valve system 

 is incompetent. 



Perthes test (72). This test is designed to evaluate the 

 competency of the saphenous and communicating 

 valves and to test for deep vein patency. A tourniquet 

 is applied to the thigh and the patient is asked to 

 walk for 5 min. If the superficial veins collapse during 

 this walk, there is an indication that the communicat- 

 ing valves are competent and the deep veins are 

 patent. If no change is observed, the indication is 

 that the communicating valves are incompetent. If 

 the superficial veins become more prominent and 

 pain is produced, there is an indication that the 

 deep veins are obstructed and the communicating 

 valves may be incompetent. This test utilizes the 

 pumping effect of exercise on venous flow. 



The Perthes test has been modified by Mahorner 

 & Ochsner (54) to determine the location of the 

 incompetent communicating veins. The modifica- 

 tion involves the application of tourniquets to the 

 upper thigh, above the knee and below the knee 

 before walking. Observations are made on the veins 

 below the tourniquet before and after each walking 

 period, and if they collapse then the communicating 

 valves below the tourniquet are competent. 



The mechanisms involved in the above and similar 

 tests should be obvious and will not be pursued 

 further. 



Determinations of venous pressure at rest and 

 during exercise are of help not only in clinical evalua- 

 tion but also in understanding the pathophysiology 

 of many manifestations of venous insufficiency (valvu- 

 lar incompetence or venous obstruction) (g, 79). 

 With significant venous obstruction or valvular incom- 

 petency, venous pressure in the leg fails to drop 

 during walking as it does in the normal. Venous 

 blood flow also fails to increase during walking. Thus, 

 high venous pressure and sluggish venous flow persist 

 during the normal daily activity of these patients. 

 When venous obstruction is marked, venous pressure 

 is even higher and the venous flow more sluggish 

 than normal even in a recumbent position. The 



increase in venous pressure is transmitted back to 

 the venules and capillaries. Thus, the many factors 

 of venous hypertension, stagnant flow, lowered blood 

 oxygen tension, compression of tissue by dilated 

 veins, delayed removal of waste products of metab- 

 olism, previous and present inflammatory reactions, 

 edema, infection, and everyday trauma combine 

 to produce the secondary manifestations of venous 

 disease such as stasis dermatitis and dermal ulcers. 

 In advanced stages, thickening of the walls, endo- 

 thelial proliferation and degenerative changes may 

 be found in arterioles as well as venules (3). 



Edema formation secondary to venous obstruction 

 or valvular incompetence is a topic of its own and will 

 not be discussed here. Some aspects, however, are 

 discussed in a subsequent section of this presentation. 



EVALUATION OF THE STATUS OF CAPILLARY AND LYM- 

 PHATIC vessels. This evaluation is available in other 

 portions of this volume. 



Special Laboratory Procedures for Examining 

 the Peripheral Circulation 



Many of the specialized laboratory procedures 

 for investigating the peripheral circulation are dis- 

 cussed elsewhere in this volume and are beyond the 

 scope of the present discussion. Such methods include 

 plethysmography, thermometry, calorimetry, intra- 

 vascular and tissue pressure recordings, circulation 

 times, blood-gas analyses, rate of radioisotopic 

 clearance, arteriography, venography, lymphangio- 

 graphy, sweat studies, nailbed and scleral capil- 

 larioscopy, infrared photography, and oscillometry. 



EFFECTS OF CIRCULATORY ARREST 



Complete circulatory arrest lies at the farthest end 

 of the spectrum from the normal state. Before pro- 

 gressing to disease, the effects of which may lie any- 

 where between these two extremes, it might be 

 beneficial to review briefly the effects of complete 

 arrest of the circulation. Much of these data are 

 found in the publications of Lewis (48, 49). 



With complete circulatory arrest the temperature 

 of the part decreases to room temperature. The rate 

 of decline is dependent upon environmental tem- 

 perature, relative humidity, and air currents. The 

 greater the mass of the part, the slower the decline. 

 Pallor is the first change in color as the blood drains 

 out of the minute vessels in the first 30 to 60 sec. 



