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Query: UMLS:C0022116 (ischemia)
 91,303 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. Posterior body reference thermograms indicate that in general a similar thermal body pattern of humans does exist. 2. The buttocks, hips, and thighs of a nude subject are thermally cool regions, possibly indicating poor vascular circulation and/or large fat concentrations. 3. Thermograms of the same anatomical area on the same subject under controlled environmental conditions are thermally similar. 4. The scapular region is from 1 to 2 deg F hotter than the sacral region for subjects reclining on Mylar. 5. The 1 deg temperature differential thermograms and the reference thermogram while the subject is on Mylar, in many ways, denote the geometrical shape of the underlying bone structure, especially the bones of the scapulae and sacrum. 6. On the degree temperatue differential thermograms, the anatomical regions most accused of being decubitus ulcer prone are the regions of highest temperatures: the scapulae, sacrum, elbows, and calves. 7. During reactive hyperemia, the visible red flare over the sacrum and coccyx becomes very intense in the first few minutes and then gradually diminishes. The thermal flare persists longer than the visible flare. The extended duration of the thermal flare over the visible red flare is attributed to a continued local elevated metabolic tissue rate caused by the previous engorgement of blood. 8. The thermal mottling seen in the first minute after releasing the load is believed to have been caused by the rapid infusion of blood and the dilation of affected vessels responsible for making up the blood flow debt which occurred during the period of ischemia. 9. A posterior body heating effect noticed immediately after the subject left the Mylar film has been attributed to the insulative qualities of the film. The cooling effect is more difficult to explain, but it is thought that the higher than average room temperature caused an increased evaporative cooling rate response of the two subjects either before getting off the film or immediately after getting off and therefore reduced the temperature of the skin. 10. The maximum reactive hyperemic temperature difference, the difference between the initial standing reference thermogram and the maximum flare temperature observed during tissue hyperemia, may be as high as 12 deg F. 11. Males on the average have larger flare patterns than females, 5.7 in.2 and 4.7 in.2, respectively. The flare areas were computed from thermograms taken 2 to 3 minutes after off-loading of tissue. 12. With the average distance from the buttock's fold to the highest and lowest thermal flare indication being lower for females (3.2 and 5.9) than for males (3.8 and 6.4), a relationship between the site or decubitus ulcer formation and the pelvic bone structure of the sexes may well exist. 13. No two thermal flare patterns are similar either in size or in shape. Thermal flare patterns occur along the centerline of the body at the sacrum and coccyx level. 14...
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PMID:Thermographical investigation of decubitus ulcers. 122 84

In order to investigate the mechanism and treatment of angina decubitus, 20 patients (18 men and 2 women aged 36-70 years) were studied during hospitalization. All patients were found to have an increased heart rate x systolic blood pressure product before the onset of angina decubitus, indicating that this type of angina pectoris belongs to the category of effort angina. Of the 11 patients investigated by continuous hemodynamic monitoring, 3 had significant progressive increases in pulmonary artery systolic pressure (PASP) and pulmonary artery diastolic pressure (PADP) before onset: their episodes of angina could not be completely controlled by digoxin and diuretics, but quickly subsided after beta blockers were added. Among the other 8 patients, PADP increased slightly in 5 and remained unchanged in 3 cases before onset: these patients had no manifestations of LV dysfunction, and beta blockers combined with coronary vasodilators produced satisfactory effects. These results indicate that LV failure is not a major factor in the pathogenesis of angina decubitus. The LV diastolic dysfunction seen in 8/11 cases may have been related to LV hypertrophy caused by long-term hypertension or chronic persistent ischemia.
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PMID:Hemodynamic observation and treatment approach for patients with angina decubitus. 136 74

Pressure is the sine qua non in the etiology of pressure sores; however, ischemia, denervation, edema, and infection also have been implicated. The role of denervation in tissue infection was studied in an isolated in vivo ovine flap model. Twenty-six adult ewes, divided into three groups, had 29 island pedicle flaps raised on their buttocks. In group I, the cutaneous nerve remained intact, while group II had its nerve divided acutely. Group III had prolonged denervation, where the nerve was divided 7 days before flap elevation. All flaps received intradermal inoculations of 10(7) Staphylococcus aureus. Ninety-six hours later, quantitative bacteriology showed counts of 10(7), 10(7), and 10(9) colony-forming units (CFU) per gram of tissue in groups I, II, and III, respectively. Septic foci were larger in group III, and there was a significant increase in tissue edema between groups I and III. A 25-fold increase in bacterial counts seen in the prolonged denervation group may help explain why neurologically injured patients are more susceptible to infection and pressure ulcerations.
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PMID:The effect of denervation on soft-tissue infection pathophysiology. 823 24

This pilot study examined the pressure-reducing properties of 11 different pressure-reducing devices as compared to a standard hospital mattress. Mean trochanteric and heel pressure readings were obtained on each surface from 13 healthy adult volunteers by using an electropneumatic pressure transducer (Gaymar, catalog # PSM1). Mean trochanteric pressures ranged from 37.2 mm Hg to 55.1 mm Hg on the pressure-reducing support surfaces as compared to 83.6 mm Hg on a standard hospital mattress. Mean heel pressure readings ranged from 28.1 mm Hg to 62.1 mm Hg on the pressure-reducing support surfaces as compared to 93.9 mm Hg on the standard hospital mattress. While pressure-reducing support surfaces were found to yield significantly lower mean pressure readings than the standard hospital mattress, none of them is capable of preventing tissue ischemia if the subcutaneous pressure is three to five times higher than the interface pressure.
Decubitus 1992 Mar
PMID:Tissue interface pressure and estimated subcutaneous pressures of 11 different pressure-reducing support surfaces. 155 91

Pressure sores are a common, expensive, and preventable complication of paralysis. They are the result of ischemia produced when tissue is compressed and distorted by pressure exerted between a bone and an external hard surface for an extended period of time. Prevention involves control of the two variables of pressure and time. Pressure can be minimized by using various pressure-reductive devices in the form of mattresses and cushions. Control of time involves scheduled position changes. If pressure sores occur, treatment consists of keeping the sore completely pressure free and clean. Grades I and II sores usually need no further treatment. Grades III and IV sores heal faster and more effectively when treated surgically.
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PMID:The cause, prevention, and treatment of pressure sores. 192 59

Prediction of surgical flap survival in a dog model was evaluated by using the technique of fluorometry. The model provides a graded variation of flap ischemia with tissue necrosis occurring at the distal end. The indicator sodium fluorescein was administered via the saphenous vein at a constant infusion rate for 20 minutes. Quantitative fluorescence measurements were obtained with surface illumination of the flap at 132 sites for 15 flaps in the five animals. Wash-in slopes and wash-out clearances, both measures of tissue perfusion, were compared with the survival of flap regions observed at seven days. The sensitivity and specificity of fluorometric wash-in and wash-out measurements were compared in their ability to predict flap survival. The study showed sensitivities of 100% and 95% and specificities of 97% and 86%, respectively for the two methods. The wash-in procedure with constant infusion may be preferable to the wash-out technique since it requires less time to complete. In addition, it avoids bolus injections thus reducing the risk of anaphylactoid reactions.
Decubitus 1989 Feb
PMID:Constant infusion fluorometry to predict flap survival. 275 34

Arachidonic acid metabolites have been implicated as mediators of progressive dermal ischemia. Decubitus ulcer formation results from chronic mechanical pressure on the skin which results in a diminished blood supply to the skin and underlying tissues. To evaluate the role of thromboxanes in pressure wounds, we measured TxB2, a stable metabolite of TxA2, in spontaneously occurring pressure wounds on Greyhound dogs. In pressure wounds in which the skin was showing early signs of pressure necrosis but was still intact, elevated TxB2 concentrations were found in healthy appearing tissues immediately adjacent to the pressure wounds, in the inner edge of the wounds, and in the center of the wounds. Significantly greater TxB2 concentrations (P less than 0.05) were found in the center of the intact wounds versus the TxB2 concentrations in the inner edge of the wounds or in healthy appearing tissues adjacent to the wounds. In pressure wounds in which the center of the wound had ulcerated or had an eschar, elevated TxB2 concentrations were found in tissues in the inner edge of the wounds and in healthy appearing tissues immediately adjacent to the pressure wounds. These results demonstrate the occurrence of elevated thromboxane concentrations in and around spontaneously occurring pressure wounds.
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PMID:Elevation of thromboxane in pressure wounds. 276 67

We examined specimens of skin overlying the sacral region, among the most common sites of bedsores, from patients with amyotrophic lateral sclerosis (ALS) and controls, and found that in ALS patients, collagen fibrils had a greater density and became more tightly packed with the duration of illness. Our results suggest that the increased density of collagen fibrils may protect the skin of ALS patients from pressure ischemia, a major cause of bedsore formation.
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PMID:Increased dermal collagen density in amyotrophic lateral sclerosis. 334 11

Ischial ulcers are the most common pressure sores in spinal cord injury patients and ischiectomy often is used in the over-all management. Because a high percentage of spinal cord injury patients with total ischiectomy had complications of the membranous and proximal bulbous urethra, we evaluated urodynamically 15 ischiectomy patients in the supine and sitting positions to determine if pressure usually borne by the ischial tuberosities was transmitted to the membranous and proximal bulbous urethra. Of the 8 patients with a complete ischiectomy at least on 1 side 5 had problems of the membranous and proximal bulbous urethra, and the average urethral pressure increase from the reclining to the sitting position was 111 cm. water. The increase in urethral pressure was not related to any change in bladder or abdominal pressure. The average urethral pressure increase in the nonischiectomy patients was only 16 cm. water and none had any problems of the membranous and proximal bulbous urethra. Some retrospective clinical studies have implicated ischiectomy in the development of these urethral complications. Our urodynamic data lend some direct evidence that a more complete ischiectomy results in excessive urethral pressure with the patient in the sitting position, thereby predisposing the membranous and proximal bulbous urethra to problems related to ischemia. Five of the 8 patients with more complete ischiectomy and 1 with bilateral partial ischiectomy had high urethral pressures and complications, such as pseudodiverticulum, diverticulum and dilatation. More incomplete ischiectomy should be used to obviate this urethral damage.
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PMID:Urethral complications following ischiectomy in spinal cord injury patients: a urethral pressure study. 380 14

Pressure ulcer and tracheal injury occurring after endotracheal intubation are clinical examples of pressure-induced tissue damage where magnitude and duration of the applied pressure are of major importance. The objective of this study was to investigate the efflux of macromolecules caused by repeated short-time ischemia induced by a pressure of 60mmHg, which causes circulatory standstill. Pressure was applied to the hamster cheek pouch and the efflux of the macromolecules of the microvasculature was evaluated by using the fluorescein isothiocyanate (FITC) dextran dye and intravital microscopy. The pressure was applied for either 1 or 5 min and repeated 8 times with a 10min restitution period in between. The repeated 1min pressure caused almost no change in microvascular efflux of FITC-dextran while 5min repeated pressure did. The gross mechanical impact on the tissue seems to be equal in the 1 and 5min exposure and thus cannot explain the difference in the developed permeability. Ischemia of such short time as 1 and 5min does not alter the energy state of the tissue significantly. The reactive hyperemia and the mediating vasoactive amines can differ markedly after 1 and 5min ischemia and can thus contribute to the permeability alteration. However, the role of vasoactive amines is unclear and further experiments are needed to determine their role.
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PMID:Microvascular changes due to repeated local pressure-induced ischemia: intravital microscopic study on hamster cheek pouch. 619 95


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