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Biomedical subjects

E Witzleb

Publications and source records attributed to E Witzleb.

At least 19 recordsLinked to original sources
PubMed1993

Volume changes in the lower leg during quiet standing and cycling exercise at different ambient temperatures.

The purpose of this study was to investigate whether ambient temperature influences both the rate of leg swelling during orthostasis and the oedema-preventing effect of the skeletal muscle pump. Using mercury-in-rubber strain gauges, volume changes were measured in the calf (n = 34) and near the ankle (n = 24) in healthy volunteers aged 19-33 years. Measurements were performed during 12 min of motionless standing in an upright posture and during 17 min of cycle exercise at intensities of 50 W and a pedalling rate of 50 rpm. The experiments were done in an air-conditioned chamber at temperatures of 20, 28 and 36 degrees C and 50% relative humidity. The rate of leg swelling, which occurred while standing, did not differ significantly among the three temperatures. The mean increases in calf volume during 10 min (min 2-12) orthostasis were 1.6 (SEM 0.1)%, 1.9 (SEM 0.2)% and 2.0 (SEM 0.2)% at 20, 28 and 36 degrees C respectively. In the ankle region the mean values were 0.9 (SEM 0.1)%, 1.0 (SEM 0.1)%, and 1.0 (SEM 0.1)% at the three temperatures, respectively. Exercising at low temperatures continuously reduced the volume of the leg, but at 36 degrees C the leg volume did not change significantly either at the calf or near the ankle. The mean volume changes measured between min 2 and min 15 were, at the calf, -1.1 (SEM 0.1)%, -0.8 (SEM 0.2)%, and -0.02 (SEM 0.1)% at 20, 28 and 36 degrees C, respectively. Near the ankle the mean changes were -0.7 (SEM 0.1)%, -0.3 (SEM 0.1)%, and +0.2 (SEM 0.1)%.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Venous pressure in the saphenous vein near the ankle during changes in posture and exercise at different ambient temperatures.

The venous pressure in the saphenous vein at the ankle was measured in ten healthy subjects (5 men, 5 women) aged 19-33 years during supine posture, orthostasis and cycle ergometer exercise (50 W, 50 rpm). Measurements were made at 20, 28 and 36 degrees C at 50% relative humidity. A custom-built setup consisting of two pressure transducers and a differential amplifier was used to compensate for the hydrostatic effects, temperature influences and movement artefacts that disturbed the pressure measurements. Pressure was lowest in the supine position and varied only slightly with the ambient temperature. The mean pressures were 7 (SEM 1) mmHg [0.9 (SEM 0.13) kPa], 7 (SEM 1) mmHg [0.9 (SEM 0.13) kPa], 4 (SEM 1) mmHg [0.5 (SEM 0.13) kPa] at 20, 28 and 36 degrees C. The venous pressure increased when the subjects were passively tilted from a supine to an upright posture. The rate of the increase was smaller at 20 degrees C than at 28 degrees and 36 degrees C. The final level the pressure reached during motionless standing differed slightly. The mean pressures were 76 (SEM 2) mmHg [10.1 (SEM 0.27) kPa], 79 (SEM 7) mmHg [10.5 (SEM 0.93) kPa] and 75 (SEM 3) mmHg [10.0 (SEM 0.40)] at the three temperatures. When starting exercising, venous pressure decreased within the 1st min to a level which remained virtually constant until the end of exercise. However, this level was found to be temperature dependent. It was lowest at 20 degrees C (26 (SEM 3) mmHg [3.5 (SEM 0.40) kPa]) and increased with temperature.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Measurements of volume changes and venous pressure in the human lower leg during walking and running.

This study investigates whether walking or running prevents the formation of edema in the lower leg. In 18 volunteers changes in calf volume were measured using strain gauge plethysmography during slow (3 km/h) and fast (6 km/h) walking or running (10 km/h) on a treadmill for 20 min each. Venous pressure was measured in a superficial vein near the ankle. Low-pass filtering removed motion artifacts from the signals. Slow walking reduced the calf volume in a biphasic manner: a rapid decrease was followed by a slow decline, lasting from about minute 2 to minute 20, its mean rate being -0.073%/min. Besides a rapid initial decrease, no significant change was observed during fast walking. During running, the calf volume first increased within 7 min to a maximum of 2.5% and subsequently decreased with a mean rate of -0.096%/min. The medians of venous pressure were 84.0, 23.5, 30.4, and 29.5 mmHg during quiet standing, slow and fast walking, and running, respectively. The experimental results prove the hypothesis that walking prevents dependent edema formation. This effect, however, cannot be fully explained by the lowered venous pressures.

Adult↗
PubMed1990

Slow volume changes in calf and thigh during cycle ergometer exercise.

To study the transcapillary fluid movements in the human lower limb in the upright body position and during muscle exercise, the slow changes in thigh and calf volumes were measured by mercury-in-rubber-strain gauge plethysmography. Measurements were carried out on 20 healthy volunteers while sitting, standing and doing cycle ergometer exercise at intensities of 50 and 100-W. A plethysmographic recording of slow extravascular volume changes during muscle exercise was possible because movement artefacts were eliminated by low-pass filtering. While standing and sitting the volumes of both thigh and calf increased due to enhanced transcapillary filtration. While standing the mean rate of increase was 0.13%.min-1 in the calf and 0.09%.min-1 in the thigh. During cycle ergometer exercise at 50 and 100 W, the calf volume decreased with a mean rate of -0.09.min-1. In contrast, the thigh volume did not change significantly during exercise at 50 W and increased at 100 W. Most of the increase occurred during the first half of the experimental period i.e. between min 2 and 12, amounting to +0.6%. Thus, simultaneous measurements revealed opposite changes in the thigh and calf. This demonstrates that the conflicting findings reported in the literature may have occurred because opposite changes can occur in different muscle groups of the working limb at the same time. Lowered venous pressure, increased lymph flow and increased tissue pressure in the contracting muscle are considered to have caused the reduction in calf volume during exercise.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

On the edema-preventing effect of the calf muscle pump.

During motionless standing an increased hydrostatic pressure leads to increased transcapillary fluid filtration into the interstitial space of the tissues of the lower extremities. The resulting changes in calf volume were measured using a mercury-in-silastic strain gauge. Following a change in body posture from lying to standing or sitting a two-stage change in calf volume was observed. A fast initial filling of the capacitance vessels was followed by a slow but continuous increase in calf volume during motionless standing and sitting with the legs dependent passively. The mean rates of this slow increase were about 0.17%.min-1 during standing and 0.12%.min-1 during sitting, respectively. During cycle ergometer exercise the plethysmographic recordings were highly influenced by movement artifacts. These artifacts, however, were removed from the recordings by low-pass filtering. As a result the slow volume changes, i.e. changes of the extravascular fluid were selected from the recorded signal. Contrary to the increases during standing and sitting the calf volumes of all 30 subjects decreased during cycle ergometer exercise. The mean decrease during 18 min of cycling (2-20 min) was -1.6% at 50 W work load and -1.9% at 100 W, respectively. This difference was statistically significant (p less than or equal to 0.01). The factors which may counteract the development of an interstitial edema, even during quiet standing and sitting, are discussed in detail. During cycling, however, three factors are most likely to contribute to the observed reduction in calf volume: (1) The decrease in venous pressure, which in turn reduces the effective filtration pressure.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1985

On physiological edema in man's lower extremity.

To examine whether the so-called musculovenous pump counteracts the development of interstitial edema in the lower extremities of man in the upright position, the volume changes in the calf which occurred during twenty minutes of rhythmic muscular exercise were measured in twenty-three subjects by impedance-plethysmography. The results were compared with the volume increase found during quiet relaxed standing for the same length of time. Contrary to the hypothesis, and edema-protective effect of the musculovenous pump could only be shown in about half the number of the subjects. In the others, muscular exercise led to increases in calf volume which were higher than those measured in the normal upright position. These results show that the calf muscle pump does not generally have a edema-protective effect but rather that muscle contractions also activate mechanisms which stimulate the extravasation of fluid. In a second test-series with twenty subjects, changes in calf volume were measured during the course of the day. In nearly all cases, the calf volume was greater in the evening than in the morning. It could be shown that the volume increases in the evening are caused by an increase in extravascular fluid. Compared to the increase in extravascular volume occurring during twenty minutes, in a normal upright position, the accumulation of extravascular fluid during the day is, however, remarkably low. Although it is still unknown how interstitial edema in man's lower extremities is prevented during the day, these findings lead to the hypothesis that the edema-preventing mechanisms, for instance the muscle-lymphpump, do not become maximally effective until a certain volume has accumulated in the interstitial space.

Adult↗
PubMed1979

[Crural phleboses. Physiological, diagnostic and therapeutic aspects (author's transl)].

On standing, the crural veins are subject to increased hydrostatic pressures impairing their function as a blood vessel and blood depot. In addition to hemodynamic changes there are shifts in the balance between capillary filtration and reabsorption in the sense of an increase in interstitial fluid volume up to the development of a visible edema. These effects may be compensated partly through the function of the so-called muscle vein pump and by venoconstrictive reactions. Insufficient compensation will entail disorders of cell supply which may lead to chronic venous insufficiency. In addition to clinical investigation methods the bi-directional ultrasonic measurement of flow velocity based on the Doppler principle is relatively simple and suitable for the functional diagnosis of superficial veins. Therapy may be initiated by physicotherapeutic, pharmacotherapeutic and surgical measures.

Humans↗