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Biomedical subjects

P M Gaylarde

Publications and source records attributed to P M Gaylarde.

At least 19 recordsLinked to original sources
PubMed1990

Venous leg ulcers and arthropathy.

Reduced ankle mobility impairs the venous muscle pump and this leads to an increase in mean venous pressure in the lower leg. We have previously shown that pressure-induced venous distension leads to cutaneous hypoxia which is caused by arteriolar vasoconstriction in response to a spinal reflex. The prolonged cutaneous hypoxia which is thus a consequence of sustained elevation of venous pressure is an important factor in the development of gravitational ulcers. It is postulated that the increased incidence of leg ulcers in patients with rheumatoid arthritis is the result of impairment of the efficiency of the venous muscle pump by reduced ankle mobility. Conversely, the elevation of venous blood pressure in patients with venous insufficiency may lead to arthropathy in the ankle. The hypothesis is presented that prolonged elevation of venous blood pressure causes injury to both the ankle joint and veins leading to chronic reciprocal damage to both. This explains the frequent association between arthropathy of the ankle and venous leg ulcers.

Ankle Joint↗
PubMed1989

The short-term benefit and long-term failure of ultraviolet light in the treatment of venous leg ulcers.

Ultraviolet light has in the past been advocated for the treatment of venous leg ulcers on the assumption that it increases skin blood flow and reduces skin hypoxia. Our results show that UV light increases skin-oxygen tension of the lower leg and inhibits the normal vasoconstrictor response on standing. However, this effect is short lived and is followed after 2 days by a return of the vasoconstrictor reflex and a marked decrease in skin oxygenation which continues for at least 2 weeks. Since UV irradiation improves skin oxygenation for only 48 h, it cannot be recommended as a form of treatment for venous leg ulcers.

Adult↗
PubMed1989

Surgical correction of venous incompetence restores normal skin blood flow and abolishes skin hypoxia during exercise.

Posture has long been recognized to be a crucial factor in the etiology of venous leg ulcers. Activation of the stretch receptors in the veins by venous distention induces reflex vasoconstriction and hypoxia. In patients with defective venous return, exercise fails to reduce venous pressure when the legs are dependent; therefore, hypoxia persists during exercise. Surgical treatment of venous incompetence abolishes the abnormal venous reflux and restores the normal vasodilator response to exercise, thereby correcting the sustained hypoxia observed in patients with venous leg ulcers.

Bandages↗
PubMed1988

Transcutaneous oxygen tension in legs and feet of diabetic patients.

Transcutaneous oxygen tension (tcPO2) of the legs and feet was measured at 37 and 44 degrees C in 21 patients with diabetes mellitus, 9 of whom had peripheral neuropathy. At 37 degrees C, tcPO2 in the legs and feet of diabetic patients with peripheral neuropathy was significantly higher (P less than .02) than in control subjects and diabetic patients without neuropathy. Whereas tcPO2 in the legs of control subjects and nonneuropathic diabetic patients was greater than in the feet (P less than .02), this leg-to-foot difference was absent in diabetic patients with neuropathy. After an increase in skin temperature to 44 degrees C, tcPO2 increased in the legs and feet of all three groups, but the increase was smallest in diabetic patients with neuropathy and greatest in control subjects. In neuropathic (P less than .02) and nonneuropathic (P less than .02) diabetic patients, tcPO2 was significantly lower than in control subjects. These data are consistent with a loss of vasoconstrictor tone in the blood vessels perfusing skin and subcutaneous tissue at 37 degrees C and an inability of these vessels to vasodilate and increase blood flow at 44 degrees C in diabetic patients in general and neuropathic diabetic patients in particular. This inability to increase tcPO2 after an increase in temperature and possibly other vasodilatory stimuli may contribute to the pathogenesis of nonhealing ulcers, protracted infections, and gangrene, which characterize the diabetic foot.

Adolescent↗
PubMed1987

The use of the Hellige Oxymonitor to study skin blood flow changes.

Transcutaneous oxygen tension is a flow related parameter. Detailed analysis of the physiology and physical chemistry of oxygen consumption and diffusion indicates that tcPO2 is not proportional to skin blood flow. Measurement of tcPO2 at 37 degrees C allows changes in skin blood flow to be clearly demonstrated and is of use in many areas of clinical medicine. Transcutaneous oxygen tension recorded using a polarographic oxygen electrode depends on skin blood flow, skin respiration, arterial oxygen concentration, temperature, skin and electrode permeability and the oxygen consumption of the electrode. Applying clearance principles, the relationship between blood flow, respiration and the difference between arterial and venous oxygen concentrations is well established. This has long been used to measure cardiac output, since the other three parameters are readily determined. Arterial saturation is normally greater than 95% of maximum in subjects without lung disease and it may thus be considered to be constant. Tissue respiration is independent of oxygen concentration when PO2 exceeds 2 mm Hg. If skin respiration is invariant at constant temperature, when the tissue oxygen tension exceeds 2 mm Hg, then blood flow is inversely proportional to the difference in concentration between arterial and venous blood. It has recently been directly shown that the inference that tissue respiration is independent of tissue blood flow is accurate. Correcting for the oxyhaemoglobin dissociation curve and for the deviation from zero order respiration kinetics when tissue PO2 less than 2 mm Hg, the relationship between venous oxygen tension and blood flow at 37 degrees C is shown when arterial oxygen concentration is constant (Figure 1).(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Flow Velocity↗
PubMed1987

Reductions in breath ethanol readings in normal male volunteers following mouth rinsing with water at differing temperatures.

Blood ethanol concentrations were measured sequentially, over a period of hours, using a Lion AE-D2 alcolmeter, in 12 healthy male subjects given oral ethanol 0.5 g/kg body wt. Readings were taken before and after rinsing the mouth with water at varying temperatures. Mouth rinsing resulted in a reduction in the alcolmeter readings at all water temperatures tested. The magnitude of the reduction was greater after rinsing with water at lower temperatures. This effect occurs because rinsing cools the mouth and dilutes retained saliva. This finding should be taken into account whenever breath analysis is used to estimate blood ethanol concentrations in experimental situations.

Adult↗
PubMed1986

Co-trimoxazole in AIDS.

Explore the source record for details and available documents.

Acquired Immunodeficiency Syndrome↗
PubMed1985

Transcutaneous oxygen tension as an index of maturity in hypertrophic scars treated by compression.

Sixteen patients undergoing compression treatment for scar hypertrophy were included in a study to evaluate physical indices of scar maturity. The results show that while thermographic measurements of scar temperature were not clinically valuable, rising levels of transcutaneous oxygen tension in treated scars correlated well with a reduction in scar thickness assessed both clinically and by ultrasound. It is postulated that low levels of tcpO2 in immature scars result from low oxygen diffusibility through scar tissue rather than from rapid metabolic consumption of oxygen by scar tissue.

Adolescent↗
PubMed1985

Skin oxygen tension in venous insufficiency of the lower leg.

Tissue anoxia has for long been invoked as a cause of venous leg ulcers, and recently it has been suggested that pericapillary fibrin prevents the diffusion of oxygen in the skin. In the present study direct measurements of skin oxygen levels on the lower leg were made using a transcutaneous oxygen monitor. In the recumbent position mean oxygen tensions were higher in patients than in controls, thus disproving the existence of any block to oxygen diffusion. In both groups there was a fall in oxygen tension to low levels on standing as a result of the normal reflex vasoconstrictor response to increased venous pressure. Exercise produced a marked rise in skin oxygen tension in normal legs but not in those affected by venous insufficiency. In normal subjects exercise reduces venous pressure, thus removing the stimulus for reflex vasoconstriction. In patients with defective valves, the venous pressure remains high during exercise and reflex vasoconstriction persists. It is concluded from this study that the sustained low skin oxygen tension in the upright position even during exercise is responsible for leg ulcer formation associated with venous insufficiency. Normal legs are protected by a rise in skin oxygenation during exercise.

Aged↗