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At least 145 records · Page 8Linked to original sources

PubMed1989

Subcutaneous metastases from malignant melanoma: prevalence and findings on CT.

We reviewed 197 body CT studies on 53 sequential patients who had a histologic diagnosis of malignant melanoma in order to determine the CT appearance, pattern of spread, and prevalence of subcutaneous melanoma metastases. Seventeen (38%) of 45 patients with CT evidence of metastatic melanoma had subcutaneous nodules shown on CT. Five patients (11%) had subcutaneous nodules as the only indication of metastatic disease on their CT scans. All patients who developed subcutaneous metastases had primary lesions classified as Clark level IV or V. (The Clark classification is based on the depth of tumor invasion and is rated I to V.) Metastases appeared as small, discrete rounded densities in the subcutaneous fat; lesions were occasionally subtle because of their small size and peripheral location. The location of subcutaneous nodules could not be predicted consistently on the basis of the site of the primary malignancy. We conclude that subcutaneous metastases are common with melanoma in patients with Clark level IV or V lesions. These subcutaneous nodules are readily detected on CT scans if the subcutaneous tissues are carefully examined. The detection of these lesions may affect management or prognosis of patients, especially in those cases where subcutaneous nodules are the only CT evidence of metastatic disease.

Adipose Tissue↗

PubMed2003

Using a phantom to compare MR techniques for determining the ratio of intraabdominal to subcutaneous adipose tissue.

OBJECTIVE: Patients who have a greater distribution of intraabdominal adipose tissue as compared with subcutaneous adipose tissue and an increased ratio of intraabdominal adipose tissue to subcutaneous adipose tissue are at greater risk for developing cardiovascular disease and type 2 diabetes mellitus. In previous MR investigations, researchers have used conventional T1-weighted spin-echo images to determine the ratio of intraabdominal adipose tissue to subcutaneous adipose tissue. However, no investigation, to our knowledge, has been performed to determine the accuracy of using different MR sequences to estimate adipose distribution. The purpose of our investigation was to compare MR imaging and segmentation techniques in calculating the ratio of intraabdominal to subcutaneous adipose tissue using an adiposity phantom. MATERIALS AND METHODS: A phantom was created to simulate the distribution of subcutaneous and intraabdominal fat (with known volumes). Axial MR images were obtained twice through the phantom using a 5-mm slice thickness and zero gap for the following T1-weighted sequences: spin-echo, fast Dixon, and three-dimensional (3D) spoiled gradient-echo. An in-house computer software program was then used to segment the volumes of fat and calculate the volume of intraabdominal adipose tissue and subcutaneous adipose tissue and the ratio of intraabdominal to subcutaneous adipose tissue. Each imaging data set was segmented three times, so six sets of data were yielded for each imaging technique. The percentage predicted of the true volume was calculated for each MR imaging technique for each fat variable. The mean percentages for each variable were then compared using one-factor analysis of variance to determine whether differences exist among the three MR techniques. RESULTS: The three MR imaging techniques had statistically significant different means for the predicted true volume of two variables: volume of subcutaneous adipose tissue (p < 0.001) and volume of intraabdominal adipose tissue (p = 0.0426). Estimates based on fast Dixon images were closest to the true volumes for all the variables. All MR imaging techniques performed similarly in estimating the ratio of intraabdominal adipose tissue to subcutaneous adipose tissue (p = 0.9117). The acquisition time for the 3D spoiled gradient-echo images was 10-22 times faster than for the other sequences. CONCLUSION: Conventional T1-weighted spin-echo MR imaging, the current sequence used in practice for measuring visceral adiposity, may not be the optimal MR sequence for this purpose. We found that the T1-weighted fast Dixon sequence was the most accurate at estimating all fat volumes. The T1-weighted 3D spoiled gradient-echo sequence generated similar ratios of intraabdominal to subcutaneous adipose tissue in a fraction of the acquisition time.

Abdominal Cavity↗

PubMed1998

Leptin secretion from subcutaneous and visceral adipose tissue in women.

Upper body obesity is a risk factor for type 2 diabetes. Little is known about the regulation of body fat distribution, but leptin may be involved. This study examined the secretion of leptin in subcutaneous and omental fat tissue in 15 obese and 8 nonobese women. Leptin secretion rates were two to three times higher in subcutaneous than in omental fat tissue in both obese and nonobese women (P < 0.0001 and P < 0.001, respectively). There was a positive correlation between BMI and leptin secretion rates in both subcutaneous (r = 0.87, P < 0.0001) and omental (r = 0.74, P < 0.0001) fat tissue. Furthermore, leptin secretion rates in subcutaneous and omental fat tissue correlated well with serum leptin levels (r = 0.84, P < 0.0001 and r = 0.73, P = 0.001, respectively), although in multivariate analysis, the subcutaneous leptin secretion rate was the major regressor for serum leptin (F = 42). Subcutaneous fat cells were approximately 50% larger than omental fat cells, and there was a positive correlation between fat cell size and leptin secretion rate in both fat depots (r = 0.8, P < 0.01). Leptin (but not gamma-actin) mRNA levels were twofold higher in subcutaneous than in omental fat tissue (P < 0.05). Thus the subcutaneous fat depot is the major source of leptin in women owing to the combination of a mass effect (subcutaneous fat being the major depot) and a higher secretion rate in the subcutaneous than in the visceral region, which in turn could be due to increased cell size and leptin gene expression.

Adipose Tissue↗

PubMed2006

The fatty acid transporter FAT/CD36 is upregulated in subcutaneous and visceral adipose tissues in human obesity and type 2 diabetes.

BACKGROUND: Long-chain fatty acids (LCFAs) cross the plasma membrane via a protein-mediated mechanism involving one or more LCFA-binding proteins. Among these, FAT/CD36 has been identified as key LCFA transporter in the heart and skeletal muscle, where it is regulated acutely and chronically by insulin. In skeletal muscle, FAT/CD36 expression and/or subcellular distribution is altered in obesity and type 2 diabetes. There is limited information as to whether the expression of this protein is also altered in subcutaneous and/or visceral adipose tissue depots in human obesity or type 2 diabetes. OBJECTIVES: To compare (a) the expression of FAT/CD36 in subcutaneous and visceral adipose tissue depots in lean, overweight, and obese individuals and in type 2 diabetics, (b) to determine whether the protein expression of FAT/CD36 in these depots is associated with the severity of insulin resistance (type 2 diabetes>obese>overweight/lean) and (c) whether FAT/CD36 protein expression in these adipose tissue depots is associated with alterations in circulating substrates and hormones. SUBJECTS: Subjects who were undergoing abdominal surgery and who were lean (n=10; three men, seven women), overweight (n=10; three men, seven women) or obese (n=7; one man, six women), or who had been diagnosed with type 2 diabetes (n=5; one man, four women) participated in this study. MEASUREMENTS: Subcutaneous and visceral adipose tissue samples, as well as blood samples, were obtained from the subjects while under general anesthesia. Adipose tissue samples were analyzed for FAT/CD36 using Western blotting. Serum samples were analyzed for glucose, insulin, FFA and leptin. BMI was also calculated. RESULTS: Subcutaneous adipose tissue FAT/CD36 expression was upregulated by +58, +76 and +150% in overweight, obese and type 2 diabetics, respectively. Relative to subcutaneous adipose tissue, visceral adipose tissue FAT/CD36 expression was upregulated in lean (+52%) and overweight subjects (+30%). In contrast, in obese subjects and type 2 diabetics, no difference in FAT/CD36 protein expression was observed between their subcutaneous and visceral adipose tissue depots (P>0.05). The subcutaneous adipose tissue FAT/CD36 expression (R=0.85) and the visceral adipose tissue FAT/CD36 expression (R=0.77) were associated with alteration in BMI and circulating glucose and insulin. CONCLUSIONS: Subcutaneous adipose tissue FAT/CD36 expression is upregulated in obesity and type 2 diabetes. As FAT/CD36 expression is not different in lean, overweight and obese subjects, and was only increased in type 2 diabetics, it appears that visceral adipose tissue FAT/CD36 may respond in a less dynamic manner to metabolic disturbances than subcutaneous adipose tissue FAT/CD36.

Adult↗

PubMed2003

Human subcutaneous tissue distribution of fluconazole: comparison of microdialysis and suction blister techniques.

AIMS: To investigate uptake of fluconazole into the interstitial fluid of human subcutaneous tissue using the microdialysis and suction blister techniques. METHODS: A sterile microdialysis probe (CMA/60) was inserted subcutaneously into the upper arm of five healthy volunteers following an overnight fast. Blisters were induced on the lower arm using gentle suction prior to ingestion of a single oral dose of fluconazole (200 mg). Microdialysate, blister fluid and blood were sampled over 8 h. Fluconazole concentrations were determined in each sample using a validated HPLC assay. In vivo recovery of fluconazole from the microdialysis probe was determined in each subject by perfusing the probe with fluconazole solution at the end of the 8 h sampling period. Individual in vivo recovery was used to calculate fluconazole concentrations in subcutaneous interstitial fluid. A physiologically based pharmacokinetic (PBPK) model was used to predict fluconazole concentrations in human subcutaneous interstitial fluid. RESULTS: There was a lag-time (approximately 0.5 h) between detection of fluconazole in microdialysate compared with plasma in each subject. The in vivo recovery of fluconazole from the microdialysis probe ranged from 57.0 to 67.2%. The subcutaneous interstitial fluid concentrations obtained by microdialysis were very similar to the unbound concentrations of fluconazole in plasma with maximum concentration of 4.29 +/- 1.19 microg ml(-1) in subcutaneous interstitial fluid and 3.58 +/- 0.14 microg ml(-1) in plasma. Subcutaneous interstitial fluid-to-plasma partition coefficient (Kp) of fluconazole was 1.16 +/- 0.22 (95% CI 0.96, 1.35). By contrast, fluconazole concentrations in blister fluid were significantly lower (P < 0.05, paired t-test) than unbound plasma concentrations over the first 3 h and maximum concentrations in blister fluid had not been achieved at the end of the sampling period. There was good agreement between fluconazole concentrations derived from microdialysis sampling and those estimated using a blood flow-limited PBPK model. CONCLUSIONS: Microdialysis and suction blister techniques did not yield comparable results. It appears that microdialysis is a more appropriate technique for studying the rate of uptake of fluconazole into subcutaneous tissue. PBPK model simulation suggested that the distribution of fluconazole into subcutaneous interstitial fluid is dependent on tissue blood flow.

Adult↗

PubMed2005

Subcutaneous tissue reapproximation, alone or in combination with drain, in obese women undergoing cesarean delivery.

OBJECTIVE: To compare the efficacy of subcutaneous suture reapproximation alone with suture plus subcutaneous drain for the prevention of wound complications in obese women undergoing cesarean delivery. METHODS: We conducted a multicenter randomized trial of women undergoing cesarean delivery. Consenting women with 4 cm or more of subcutaneous thickness were randomized to either subcutaneous suture closure alone (n = 149) or suture plus drain (n = 131). The drain was attached to bulb suction and removed at 72 hours or earlier if output was less than 30 mL/24 h. The primary study outcome was a composite wound morbidity rate (defined by any of the following: subcutaneous tissue dehiscence, seroma, hematoma, abscess, or fascial dehiscence). RESULTS: From April 2001 to July 2004, a total of 280 women were enrolled. Ninety-five percent of women (268/280) had a follow-up wound assessment. Both groups were similar with respect to age, race, parity, weight, cesarean indication, diabetes, steroid/antibiotic use, chorioamnionitis, and subcutaneous thickness. The composite wound morbidity rate was 17.4% (25/144) in the suture group and 22.7% (28/124) in the suture plus drain group (relative risk 1.3, 95% confidence interval 0.8-2.1). Individual wound complication rates, including subcutaneous dehiscence (15.3% versus 21.8%), seroma (9.0% versus 10.6%), hematoma (2.2% versus 2.4%), abscess (0.7% versus 3.3%), fascial dehiscence (1.4% versus 1.7%), and hospital readmission for wound complications (3.5% versus 6.6%), were similar (P > .05) between women treated with suture alone and those treated with suture plus drain, respectively. CONCLUSION: The additional use of a subcutaneous drain along with a standard subcutaneous suture reapproximation technique is not effective for the prevention of wound complications in obese women undergoing cesarean delivery.

Adipose Tissue↗

PubMed1988

Pharmacokinetics of subcutaneous methotrexate.

The pharmacokinetics of subcutaneously administered methotrexate was studied as a parenteral alternative to oral administration. An initial feasibility study was performed in Rhesus monkeys comparing the subcutaneous route to intravenous (IV) injection and oral administration. The subcutaneous dose was completely absorbed and a sustained-release effect was observed when compared with the IV dose. No local or systemic toxicities resulted from subcutaneous methotrexate in the animals. Twelve children with acute lymphoblastic leukemia on maintenance therapy protocols prescribing either 7.5 mg/m2 biweekly or 40 mg/m2 weekly were also monitored after both a subcutaneous and an oral dose of methotrexate. Four children at the higher dosage level were also studied after an equal IV dose. The subcutaneous dose was again completely absorbed in these children at both dose levels, whereas the oral dose, which produced comparable plasma drug concentrations at the lower dosage level, resulted in a total drug exposure (area under the plasma concentration-time curve) that was one third that of the equal subcutaneous dose at the higher dosage level. No local or systemic toxicity was attributed to the subcutaneous methotrexate. Subcutaneous administration of methotrexate is well tolerated and well absorbed and appears to overcome the problems associated with oral administration, including variable absorption and saturation of the absorption mechanism with increasing doses.

Absorption↗

PubMed2001

Fludarabine pharmacokinetics after subcutaneous and intravenous administration in patients with lupus nephritis.

STUDY OBJECTIVE: To compare the pharmacokinetics of subcutaneous and intravenous fludarabine in patients with lupus nephritis. DESIGN: Open-label, randomized, crossover trial conducted with a phase I-II trial. SETTING: Government research hospital. PATIENTS: Five patients with lupus nephritis. INTERVENTION: Fludarabine 30 mg/m2/day was administered either subcutaneously or as a 0.5-hour intravenous infusion for 3 consecutive days. All patients received oral cyclophosphamide 0.5 g/m2 on the first day of each cycle. MEASUREMENTS AND MAIN RESULTS: Plasma samples were collected before and 0.5, 1, 1.5, 2, 4, 8, and 24 hours after the first dose. Urine was collected at 6-hour intervals for 24 hours. Plasma and urine were analyzed for fluoro-arabinofuranosyladenine (F-ara-A), fludarabine's main metabolite, using high-performance liquid chromatography. Compartmental techniques were used to determine the pharmacokinetics of F-ara-A; a linear two-compartment model best described them. Comparison of the pharmacokinetics between subcutaneous and intravenous administration was done by using a Wilcoxon signed rank test. No significant differences were found between subcutaneous and intravenous administration in median (interquartile range) maximum concentrations of 0.51 (0.38-0.56) and 0.75 (0.52-0.91) mg/L, respectively, or in fitted area under the concentration-time curves from 0-24 hours of 4.65 (4.17-4.98) and 4.55 (3.5-4.94) mg x hour/L, respectively. Bioavailability of F-ara-A after subcutaneous dosing was approximately 105% of the bioavailability after intravenous administration. Differences in renal clearance and percentage of dose excreted in urine for subcutaneous and intravenous administration were nonsignificant. No injection site reactions were seen with subcutaneous dosing. CONCLUSION: Subcutaneous and intravenous administration of fludarabine appear to have similar pharmacokinetics in patients with lupus nephritis. Subcutaneous injection may offer a convenient alternative to intravenous administration.

Adult↗

PubMed2005

Intermittent subcutaneous methadone administration in the management of cancer pain.

Methadone is a strong opioid analgesic that has been used successfully in cancer pain management. The oral route of administration is generally preferred for opioid analgesics. However that route sometimes cannot be used. Experience with continuous subcutaneous methadone infusions has produced local intolerance. The aim of this study was to analyze the use of intermittent subcutaneous methadone injections. Ten patients whose pain was well-controlled with oral methadone (average dose 30 mg, range 10 to 120 mg) participated in the study. A subcutaneous small vein needle (butterfly) was used exclusively for administration of methadone. Over a period of seven days the local discomfort of each injection was evaluated by means of a Verbal Numerical Rating Scale (NRS) and the site of infusion was observed. When any degree of erythema or inflammation was seen, the infusion site was changed. The initial subcutaneous dose was the same as the previously administered oral dose. A daily record was kept of the dose used, level of pain, and toxicity symptoms. This close vigilance was aimed at avoiding dosage errors due to variations among individuals in acceptance to previous oral medication. Changes in dosage were allowed according to standard medical criteria. Two patients were withdrawn from the study due to non-painful irritation at the infusion point. Another eight patients tolerated repeated administration of subcutaneous methadone over seven days. Any local irritation from subcutaneous methadone that occurred was managed satisfactorily by changing the infusion site and limiting doses to 30 mg. In seven of 182 repeat administration, injection site changes were necessitated by local irritation. The NRS for local discomfort was 2/10. The two patients who were intolerant of the subcutaneous injections were receiving injected doses which were significantly higher than the others (42 mg as compared to 25 mg). Dose adjustments needed when changing from the oral to the subcutaneous methadone route were minimal. Subcutaneous intermittent administration of methadone appears to be a useful alternative to oral administration in selected clinical situations when oral administration is not feasible.

Aged↗

PubMed2006

Subcutaneous tissue thickness in children with type 1 diabetes.

AIM: This paper reports a study to measure the thickness of subcutaneous tissue at three major injection sites and to identify frequently used injection sites and injection methods. BACKGROUND: Glycaemic control is the key factor in the management of children with type 1 diabetes, and subcutaneous injection of insulin plays a major role in glycaemic control. However, only limited studies have examined the thickness of subcutaneous tissue at various injection sites. METHODS: The subcutaneous thickness in a convenience sample of 65 children aged 8-16 years attending a diabetes camp in 2002 was measured once per child at the outer arm, anterior thigh, and abdomen by one investigator using a Lange caliper. Injection sites and the method of injection were observed daily for four days by a trained investigator using a checklist. RESULTS: Median values of subcutaneous thicknesses at the outer arm, anterior thigh, and anterior abdomen for girls were respectively 18.00, 18.00 and 19.75 mm, and for boys were 17.00, 12.50 and 17.00 mm. In 40% of participants, the thickness of the subcutaneous tissue of the abdomen was <12.5 mm. Boys over 14 years old had statistically significantly thinner subcutaneous tissue at all injection sites than that of age-matched girls. The anterior abdomen was the most common injection site in boys, and the anterior thigh in girls. Perpendicular injection without skin-folding was the most frequently used injection method. Body Mass Index was statistically significantly correlated with subcutaneous tissue thickness at all sites. CONCLUSION: A needle shorter than a 12.5-mm needle should be used, particularly for boys. Injection with skin-folding may decrease the possibility of intramuscular injection.

Adolescent↗

PubMed1994

Intrapartum fetal subcutaneous tissue/femur length ratio: an ultrasonographic clue to fetal macrosomia.

OBJECTIVE: Our purpose was to compare the accuracy of ultrasonographic intrapartum measurement of fetal abdominal circumference, estimated fetal weight, and fetal subcutaneous tissue/femur length ratio in predicting large-for-gestational-age fetuses. STUDY DESIGN: A cross-sectional analysis of 173 normal patients delivered of normal, appropriate-for-gestational-age infants (group 1) was performed to determine the normal changes of standard fetal biometric parameters and subcutaneous tissue throughout pregnancy. Measurements of fetal subcutaneous tissue were made at the level of the femoral diaphysis. A second group of 101 well-dated patients had these measurements obtained within 24 hours of delivery (group 2). Large for gestational age was defined as a birth weight > 90th percentile for gestational age. The sensitivity and specificity for prediction of large for gestational age of an intrapartum measurement of an abdominal circumference > 90th percentile, estimated fetal weight > 90th percentile, and fetal subcutaneous tissue/femur length ratio > 2 deviations of the mean was calculated. RESULTS: In group 1 the mean gestational age was 31.4 +/- 5.4 weeks (range 17 to 41 weeks). The femur length, abdominal circumference, and fetal subcutaneous tissue correlated well with gestational age (p < 0.0001). The fetal subcutaneous tissue/femur length ratio was stable throughout pregnancy, with a mean of 0.05 +/- 0.014 (range 0.02 to 0.09, R2 0.09). In group 2 mean gestational age was 38 +/- 2.5 weeks (range 30 to 42 weeks). Mean birth weight was 3280 +/- 740 gm (range 1513 to 4801 gm). Nineteen (19%) fetuses were large for gestational age. Significant differences were found between the appropriate- and large-for-gestational-age fetuses for birth weight, abdominal circumference, estimated fetal weight, and fetal subcutaneous tissue/femur length ratio (p < 0.0001). The sensitivity and specificity of the fetal abdominal circumference, estimated fetal weight, and fetal subcutaneous tissue/femur length ratio were 44% and 98%, 68% and 85%, and 82% and 96%, respectively. CONCLUSION: The fetal subcutaneous tissue/femur length ratio is a gestational age-independent parameter that has a greater sensitivity than the fetal abdominal circumference or estimated fetal weight formula for the intrapartum identification of large-for-gestational-age fetuses.

Abdomen↗

PubMed1996

Subcutaneous abdominal adipose tissue blood flow: variation within and between subjects and relationship to obesity.

1. We assessed the variation in subcutaneous abdominal adipose tissue blood flow within and between subjects and investigated whether it is correlated with body mass index. 2. We measured body mass index and subcutaneous abdominal adipose tissue blood flow in 38 fasting subjects on the same day and on different days and, in a subgroup of 16 subjects, after a mixed meal. 3. In 190 measurements in the fasted state, subcutaneous abdominal adipose tissue blood flow was significantly more variable between subjects than could be accounted for by the within-subject variation alone. Subcutaneous abdominal adipose tissue blood flow was also significantly more variable between days within subjects than could be accounted for by within-day variation alone. Fasting and post-prandial subcutaneous abdominal adipose tissue blood flow were negatively correlated with body mass index, as was the post-prandial rise in subcutaneous abdominal adipose tissue blood flow. Multiple regression analysis showed that fasting blood flow was not dependent on insulin concentration after allowing for body mass index. There was no correlation between post-prandial subcutaneous abdominal adipose tissue blood flow and insulin concentration. 4. Insulin does not appear to have a direct vasodilatory effect in subcutaneous adipose tissue. Obese subjects have lower fasting and post-prandial subcutaneous abdominal adipose tissue blood flow. This may be because of a blunted response to sympathetic stimulation, or it may be another aspect of the insulin-resistant state.

Abdomen↗

PubMedDate not supplied

Centrally and locally mediated thermoregulatory responses alter subcutaneous oxygen tension.

Mild perianesthetic hypothermia decreases resistance to infections. Decreased resistance likely results in part from direct immune inhibition. However, decreased tissue oxygen partial pressure also decreases resistance to infection by impairing oxidative killing by neutrophils and collagen deposition. Thermoregulatory vasoconstriction decreases skin blood flow and may also decrease subcutaneous tissue oxygen tension. Accordingly, we determined the influence of centrally and locally mediated thermoregulatory vasomotion on subcutaneous oxygen tension. We also compared subcutaneous oxygen tension to other potential markers of tissue perfusion: laser Doppler flowmetry and transcutaneous oxygen tension. Arterial oxygen tension was maintained near 325 mm Hg in five volunteers. Control subcutaneous oxygen tension values were recorded after 1 hour of euthermia (no sweating or vasoconstriction). Volunteers were then cooled with a circulating-water mattress positioned under the trunk and legs. After 1.5 hours of cooling sufficient to produce shivering, the right upper arm was covered for 1 hour with a small circulating water blanket set to 40 degrees C while systemic cooling continued. The volunteers were then systematically warmed to produce sweating, and the right arm was locally cooled. There was no correlation among laser Doppler flowmetry, transcutaneous oxygen tension, and subcutaneous oxygen tension. Systemic cooling significantly decreased subcutaneous oxygen tension, but subcutaneous oxygen tension in the right arm returned to control values during local heating. Systemic warming significantly increased subcutaneous oxygen tension, and 1 hour of local cooling failed to fully reverse the increase. These data indicate that thermoregulatory vasoconstriction significantly decreases tissue oxygen availability. Decreased subcutaneous oxygen tension may be one mechanism by which mild perianesthetic hypothermia facilitates development of surgical wound infections.

Journal Article↗

PubMed1998

Effect of a single element subcutaneous array electrode added to a transvenous electrode configuration on the defibrillation field and the defibrillation threshold.

Even with the use of biphasic shocks, up to 5% of patients need an additional subcutaneous lead to obtain a defibrillation safety margin of at least 10 J. The number of patients requiring additional subcutaneous leads may even increase, because recent generation devices have a < 34 J maximum output in order to decrease their size. In 20 consecutive patients, a single element subcutaneous array lead was implanted in addition to a transvenous lead system consisting of a right ventricular (RV) and a vena cava superior lead using a single infraclavicular incision. The RV lead acted as the cathode; the subcutaneous lead and the lead in the subclavian vein acted as the anode. The biphasic defibrillation threshold was determined using a binary search protocol. Patients were randomized as to whether to start them with the transvenous lead configuration or the combination of the transvenous lead and the subcutaneous lead. In addition, a simplified assessment of the defibrillation field was performed by determining the interelectrode area for the transvenous lead only and the transvenous lead in combination with the subcutaneous lead from a biplane chest X ray. The intraoperative defibrillation threshold was reconfirmed after 1 week, after 3 months, and after 12 months. The mean defibrillation threshold with the additional subcutaneous lead was significantly (P = 0.0001) lower (5.7 +/- 2.9 J) than for the transvenous lead system (9.5 +/- 4.6 J). With the subcutaneous lead, the impedance of the high voltage circuit decreased from 48.9 +/- 7.4 omega to 39.2 +/- 5.0 omega. In the frontal plane, the interelectrode area increased by 11.3% +/- 5.5% (P < 0.0001) and in the lateral plane by 29.5% +/- 12.4% (P < 0.0001). The defibrillation threshold did not increase during follow-up. Complications with the subcutaneous electrode were not observed during a follow-up of 15.8 +/- 2 months. The single finger array lead is useful in order to lower the defibrillation threshold and can be used in order to lower the defibrillation threshold.

Aged↗

PubMed1975

[The subcutaneous vascular system (lower extremity): studies on micro-preparations].

At the level of fascial penetration the cutaneous arteries of the lower extremity are constantly accompanied by 1 or 2 communicating veins of varying diameter. Usually, they penetrate the fascia in rows via the muscular interstitium. There they give up branches to the fascial vascular network, to pre- and subfascial areolar tissue and possibly to the muscle origins on the fascia, or to the intermuscular septa. The texture of the fascia itself determines the structure of fascial openings for the cutaneous vessels. In the subcutaneous tissue the arteries are accompanied by 1 or 2 veins (Vv. comitantes). Numerous arterio-arterial and intervenous anastomoses form a subcutaneous network of vascular bundles. Two anastomosing venous systems can be distinguished in the subcutis: The small Vv. comitantes are fed primarily by the subcutaneous adipose lobes, and end in communicating veins or flow into the subcutaneous veins (epifascial veins). These large subcutaneous veins on the other hand are responsible for the actual outflow from the venous network of the cutis. They form the saphenous system or empty into larger communicating veins. Between the subcutaneous arterioles and accompanying venules there are numerous capillary webs. In addition direct capillaries and looped as well as meandering or knotted arterio-venous shunts are found. The subcutaneous vascular bundles are fixed by a connective tissue. There are often typical capillary meshes within arterial sheat, oriented like a rope-ladder. They undergo prenatal development. The subcutaneous (epifascial) veins are surrounded by areolar tissue on the cutaneous as well as on the fascial side. Fibers from the accompanying connective tissue criss-cross into the adventitia and thereby anchor the veins in a movable fashion. Typical vascular patches with plane capillary networks characterize the areolar tissue around the subcutaneous veins, which is differentiating at the 2nd half of the fetal period. Within are also capillary loops and convoluted arterio-venous shunts.

Adult↗

PubMed1988

Improved radioimmunolocalization of human tumor xenografts following subcutaneous delivery of monoclonal antibodies.

The localization of a radiolabeled murine monoclonal antibody reactive with choriocarcinomas to human choriocarcinoma xenografts following intravenous and subcutaneous injection was evaluated by gamma scanning and tissue sampling. Tumor xenografts were established in the popliteal node region of athymic nude mice after repeated innoculations of the hind foot pads with BEWO choriocarcinoma cells. In dual label specific antibody studies, tumor/non tumor uptake ratios following subcutaneous (resulting in considerable intralymphatic uptake) injection of 131I-5F9.3 were significantly higher than those achieved post simultaneous intravenous injection of 125I-5F9.3. Double label experiments with 131I-5F9.3 and a nonspecific antibody, 125I-UPC-10, following subcutaneous injection, demonstrated that the high localization to popliteal region tumors was largely due to antibody specificity. Gamma scans following subcutaneous antibody administration of specific antibody to tumor bearing animals showed tumors soon after subcutaneous injection, at times earlier than those typically seen following intravenous delivery. Similar subcutaneous injections showed little normal nodal uptake in BALB/c control animals on gamma scans. No correlation was seen between tumor localization by specific antibody between the intravenous and intralymphatic routes, implying a difference in the mechanisms of tumor uptake of antibody by these two routes. The subcutaneous approach to antibody delivery offers advantages over intravenous delivery in tumors of human origin, including higher tumor/non tumor ratios and earlier imaging times. This was true even though these tumors were many times larger than normal lymph nodes. This subcutaneous delivery advantage should be exploitable in imaging nodal metastases of human tumors.

Animals↗

PubMed1996

Postprandial insulin profiles with implantable pump therapy may explain decreased frequency of severe hypoglycemia, compared with intensive subcutaneous regimens, in insulin-dependent diabetes mellitus patients.

PURPOSE: To examine the mechanism of the decreased frequency of severe hypoglycemia with implantable pump therapy compared with subcutaneous intensive therapy. PATIENTS AND METHODS: Eight subjects with insulin-dependent diabetes mellitus (IDDM), enrolled in an implantable insulin pump study, were admitted to the General Clinical Research Center and on 2 separate days were given either a dose of preprandial insulin chosen to maintain normoglycemia for a standard (450 kcal, 50% carbohydrate) breakfast or 1.75 times the dose. The two doses were administered subcutaneously (by syringe or with an external pump) during one inpatient admission and by implantable pump (intraperitoneally, n=6; or intravenously, n=2) during a separate admission. Blood glucose, plasma-free insulin, and neurocognitive function were measured for 4 hours after the meal. RESULTS: Subcutaneous administration resulted in 7 episodes of hypoglycemia (2 with the usual dose and 5 with the 1.75-fold dose), defined as blood glucose less than 50 mg/dL; implantable pump treatment resulted in only 2 episodes, both with the 1.75-fold dose (P <0.05, Fisher's two-tailed test for implantable versus subcutaneous). Compared with subcutaneous delivery, implantable pump therapy provided significantly lower insulin levels during the final 2 hours after administration of the usual dose and the 1.75-fold dose (P <0.005). In addition to the decreased frequency of hypoglycemia, implantable pump therapy resulted in significantly lower area under the glycemia curve during the first 120 minutes with the 1.75-fold dose compared with subcutaneous administration. CONCLUSIONS: The lower frequency of severe hypoglycemia with intensive therapy administered by implantable pump therapy is explained by the more rapid clearance of insulin delivered intraperitoneally or intravenously compared with intensive subcutaneous injection regimens. The lower frequency of severe hypoglycemia with implantable pump therapy compared with subcutaneous therapy demonstrated in clinical trials is confirmed by this study, in which we attempted to induce hypoglycemia.

Adult↗

PubMed2000

A new therapeutic option by subcutaneous recombinant hirudin in patients with heparin-induced thrombocytopenia type II: a pilot study.

We prospectively studied 15 patients suffering from acute heparin-induced thrombocytopenia (HIT) type II with and without thromboembolic events and 4 patients with anamnestically known HIT type II recurrently requiring thromboprophylaxis in order to develop new therapeutic strategies by subcutaneous recombinant hirudin administration. Patients with acute venous or arterial thromboembolism were treated with aPTT-controlled intravenous (mean: 19.3 days) followed by subcutaneous r-hirudin (mean: 22.5 days). Patients without thromboembolism were treated with subcutaneous r-hirudin (mean: 25.9 days). Four patients were readmitted to subcutaneous r-hirudin (mean: 32 days). When r-hirudin was administered subcutaneously following intravenous treatment, mean baseline (prior to the injection) and mean peak (1.5-2.5 hours after the injection) aPTT ratios were 1.1 (+/-0.2) to 1.7 (+/-0.48) and 2. 48 (+/-0.43) to 2.52 (+/-0.4) times normal value, respectively. Mean baseline and mean peak ECT ratios were 1.2 (+/-0.12) to 1.9 (+/-0. 22) and 2.2 (+/-0.25) to 2.6 (+/-0.11) times the upper normal value, respectively. When r-hirudin was initially administered subcutaneously, mean baseline and mean peak aPTT ratios were 1.41 (+/-0.25) to 1.61 (+/-00.28) and 1.88 (+/-0.26) to 2.06 (+/-0.09) times the normal value, respectively. Mean baseline and mean peak ECT ratios were 1.25 (+/-0.2) to 1.5 (+/-0.38) and 2.01 (+/-0.21) to 2.23 (+/-0.25) times the upper limit of normal, respectively. Patients who received recurrent subcutaneous r-hirudin had mean baseline and peak aPTT values of 1.5 (+/-0.35) to 1.75 (+/-0.156) and 2.0 (+/-0.33) to 2.1 (+/-0.18) times the normal value, respectively. Mean baseline and peak ECT ratios were 1.3 (+/-0.26) to 1.65 (+/-0.09) and 1.94 (+/-0.256) to 2.7 (+/-0.23) times the upper limit of normal, respectively. The overall cumulative incidence of r-hirudin antibodies was 12/19 (63%) with a significant accumulation of r-hirudin in antibody-positive patients compared to antibody-negative patients (p<0.05). No patient suffered a new thromboembolic or major bleeding event. Subcutaneous administration of recombinant hirudin provides a long-term thromboprophylaxis regimen in HIT type II patients after passivation of acute thromboembolism.

Adult↗