Vein Catheterization Research Articles

AT 1 receptors mediate chronic central nervous system AII hypertension in rats fed high sodium chloride diet from weaning

CNS angiotensin II (AII) hypertension is induced by chronic, low dose intracerebroventricular (ICV) AII infusion only in rats raised on a relatively high sodium chloride diet (250 meq kg −1 food) from weaning. This experimental model of hypertension is dependent upon renal sympathetic innervation and associated with neurogenic sodium retention. This study determined whether AT 1 and/or AT 2 receptor subtypes in the CNS mediate this neurogenic ICV AII hypertension. Rats were weaned at 21 days of age and fed a 1.5% sodium chloride diet for 10–12 weeks. At adulthood, animals were instrumented with CNS lateral ventricular cannulas, femoral arterial and vein catheters and housed in metabolic pens for chronic study. Low dose ICV AII infusion (20 ng min −1) increased mean arterial pressure by 12±2 mm Hg and decreased urinary sodium excretion for three consecutive days. Subsequent ICV AT 1 blockade with losartan abolished both the pressor and antinatriuretic responses to low dose ICV AII. In contrast, ICV AT 2 receptor blockade with PD 123319 did not affect either angiotensin induced pressor or antinatriuretic responses. Following cessation of ICV AII infusion, arterial pressure and sodium excretion returned to values not significantly different from control in both groups of rats. These data confirm that low dose ICV AII causes hypertension and sodium retention in rats raised from early age on moderately elevated sodium intakes. This AII mediated neurogenic hypertension and antinatriuresis is transduced by activation of CNS AT 1 receptors and not by activation of central AT 2 receptors.

Incidence and risk factors of catheter-related deep vein thrombosis in a pediatric intensive care unit: a prospective study.

To estimate the incidence and to characterize risk factors for central venous catheter (CVC)-related deep vein thrombosis (DVT) in a pediatric intensive care unit. Consecutive children admitted to a pediatric intensive care unit who required a CVC for more than 48 hours were examined by Doppler ultrasonography of the catheterized vein at days 2, 4, 6, or 7 after insertion and weekly thereafter until CVC removal. The incidence of CVC-related DVT was 18.3% (17 of 93) (95% confidence interval = 10.2% to 25.8%). Thromboses were diagnosed within the first 4 days of catheter placement for 15 of 17 CVC-related thromboses. Multivariate analysis showed that risk factors most predictive of CVC-related DVT were presence of a cancer (odds ratio = 17.23, 95% confidence interval = 1.5 to 194) and young age (odds ratio for age = 0.72, 95% confidence interval = 0.54 to 0.96). The frequency of CVC-related DVT is substantial in pediatric intensive care units. Risk is highest during the 4 days after insertion and decreases thereafter. The clinical impact, optimal prevention, and therapy of these thromboses remain to be determined.

Electrical potential difference between exocelomic fluid and maternal blood in early pregnancy.

The forces that drive transfer of solutes between maternal blood and embryo in early human pregnancy are poorly understood. The aim of this study was to determine whether there is an electrical potential difference (PD) between maternal blood and the exocelomic cavity and between maternal blood and the amniotic cavity in the normal human conceptus at or before 10 wk of pregnancy. We measured PD between a saline-filled catheter in a forearm vein of women undergoing termination of pregnancy for psychological reasons in the first trimester and a second saline-filled catheter in the exocelomic cavity or amniotic cavity of their conceptus. The mean (+/- SE) maternal blood/exocelomic cavity PD in eight women was 8.7 +/- 1.0 mV and the mean maternal blood/amniotic cavity PD in four of the women was 6.7 +/- 1.3 mV, embryo side negative for both sets of measurement. These data show that there is a PD between maternal and embryonic extracellular fluid in the first trimester that will directly influence exchange of ions between the two compartments.

Maintenance of baseline angiotensin II potentiates insulin hypertension in rats.

Chronic insulin infusion in rats increases mean arterial pressure (MAP) by a mechanism dependent on angiotensin II (Ang II). However, the fact that plasma renin activity (PRA) decreases with insulin infusion suggests that Ang II sensitivity is increased and that the parallel reduction in Ang II may partly counteract any hypertensive action of insulin. This study tested that hypothesis by clamping Ang II at baseline levels during chronic insulin infusion. Sprague-Dawley rats were instrumented with artery and vein catheters, and MAP was measured 24 hours per day. In seven angiotensin clamped rats (AC rats), renin-angiotensin II system activity was clamped at normal levels throughout the study by continuous intravenous infusion of the angiotensin-converting enzyme inhibitor benazepril at 5 mg/kg per day (which decreased MAP by 18+/-2 mm Hg) together with intravenous Ang II at 5 ng/kg per minute. Control MAP in AC rats after clamping averaged 99+/-1 mm Hg, which was not different from the 101+/-2 mm Hg measured before clamping Ang II levels. Control MAP in the 8 vehicle-infused rats averaged 105+/-2 mm Hg. A 7-day infusion of insulin (1.5 mU/kg per minute IV) plus glucose (20 mg/kg per minute IV) increased MAP in both groups of rats; however, the increase in MAP was significantly greater in AC rats (12+/-1 versus 5+/-1 mm Hg). This enhanced hypertensive response to insulin in AC rats was associated with a greater increase in renal vascular resistance (153+/-10% versus 119+/-6% of control) and a significant increase in renal formation of thromboxane (149+/-11% of control). Thus, decreased Ang II during insulin infusion limits the renal vasoconstrictor and hypertensive actions of insulin, and this may be caused, at least in part, by attenuation of renal thromboxane production.

Technical aspects of catheter-related interventions in the liver of the rabbit.

On the basis of 89 different vascular interventions performed in the livers of 39 rabbits, we attempted to establish the feasibility and technical limitations of these procedures. Forty-five selective hepatic artery catheterizations were carried out using 0.66-mm and 1.0-mm catheters, including superselective proper hepatic catheterizations (n = 14) using a specially designed 0.66-mm introducer/catheter system. The portal system was investigated with both direct (n = 5) and indirect (arterial) (n = 4) portography. Hepatic, vein catheterizations were performed in 22 cases. With the 0.66-mm system, spasm occurred in one of 11 cases in the proper hepatic artery, and no spasm was observed in the common hepatic and celiac arteries. Both arterial portography and hepatic venography were easily performed and were a precise and repeatable method. The 0.66-mm system has proved to be advantageous over the 1.0-mm catheterization in avoiding arterial spasm. Direct portography as well as catheterization of the hepatic vein from a jugular approach are hazardous, leading to serious complications including the death of the animal.

Comparison of some properties of pronethalol and propranolol. 1965.

Comparison of some properties of pronethalol and propranolol. 1965.

Chronic adrenergic receptor blockade does not prevent hyperinsulinemia-induced hypertension in rats

Increased adrenergic activity has been suggested to mediate the hypertension associated with hyperinsulinemia. This study tested whether combined alpha1- and beta-adrenergic receptor blockade would prevent insulin-induced hypertension when euglycemia was maintained by continuous intravenous glucose infusion. Sprague-Dawley rats (n = 16) were instrumented with artery and vein catheters and placed in metabolic cages. Propranolol and prazosin (10 mg/kg/day each) were infused continuously intravenously in 9 rats and 7 other rats received vehicle. Mean arterial pressure (MAP) and heart rate (HR) were measured 24 h per day using computerized methods. After a control period, a 7-day intravenous infusion of insulin (1.5 microU/kg/min) was begun and glucose was coadministered intravenously at 23 mg/kg/min to prevent hypoglycemia. The MAP averaged 93 +/- 1 mm Hg in the blockade rats during the control period, which was significantly lower than the 98 +/- 1 mm Hg in the normal rats. During insulin infusion, MAP increased similarly in both groups, with a 10 +/- 2 mm Hg and 11 +/- 1 mm Hg increase in normal and blockade rats, respectively, by day 7. The HR also increased in both groups: from 417 +/- 8 beats/ min to 426 +/- 13 beats/min (P = NS) in normal rats and from 379 +/- 10 beats/min to 419 +/- 10 beats/min (P < .05) in blockade rats. Control sodium excretion averaged 2.5 +/- 0.1 mEq/day in both groups and no significant change in sodium balance was measured in either group. All variables returned toward control after stopping insulin. These results suggest that increased adrenergic activity is not required for chronic hyperinsulinemia to raise blood pressure in rats.

Interaction between cold and hypoxia on pulmonary circulation in COPD.

This study was designed to investigate the interaction of mild and localized cold exposure and hypoxia on pulmonary hemodynamics in chronic obstructive pulmonary disease (COPD). Nineteen patients with COPD were studied at sea level and seven at an altitude of 2,640 m. For all patients, pulmonary hemodynamic measurements were performed 10 min after insertion of a catheter in a femoral vein and following 10 min of cold exposure. Cold exposure was restricted to the forehead, and subjects breathed air at ambient temperature. Flow and temperature of air (1.5 L.s(-1), 5 degrees C) to the forehead were chosen to cool down the forehead skin to approximately 20 degrees C without discomfort for the subject. For the seven patients studied at high altitude, the same measurements were also performed after 5 min of oxygen supplementation with and without cold exposure. At sea level, an increase in pulmonary vascular resistance (PVR) during cold exposure was inversely related to the initial PaO2. In six severe hypoxic subjects (PaO2 < 50 mm Hg), PVR increased by 24%. At high altitude, PVR was significantly increased by 15%. After O2 supplementation, cold exposure did not induce an increase in PVR. We concluded that mild and localized cold exposure to the forehead only induced an increase in PVR in COPD patients with severe hypoxia. Moreover, in cold exposure responders, O2 supplementation negated the effect of cold exposure on pulmonary hemodynamics.

Effects of hypercholesterolaemia on physiological recruitment of coronary vascular reserve in swine.

1. The endothelium participates in the regulation of coronary vascular tone. As evidence exists from studies performed on epicardial vessels that hypercholesterolaemia impairs endothelial function, we tested the hypothesis that hypercholesterolaemia impairs coronary vascular reserve in an intact animal. 2. Domestic swine, maintained on a regular (n = 9) or a 2% high-cholesterol (n = 9) diet for 3 months were instrumented with a catheter in the left atrium for microsphere injection, a catheter in the anterior interventricular vein for venous sampling and an 82% stenosis in the left anterior descending artery. Papaverine was used to determine coronary vascular reserve. Regional coronary flow as reflected by perfusion (microsphere measurement), lactate consumption, oxygen consumption and haemodynamics were obtained at baseline, after 10 mg of papaverine and after atrial pacing at a rate of 120 beats/min and 150 beats/min. 3. Cholesterol was elevated in animals on the high cholesterol diet (350 +/- 50 mg/dl versus 99 +/- 10 mg/dl, P < 0.001). Baseline haemodynamics were similar between groups. Baseline transmural flow and its augmentation with papaverine were comparable in the two groups in the control (circumflex) and stenosed (left anterior descending artery) zones. In both groups, perfusion increased in the control zone in response to increased oxygen demand, whereas in the stenosis zone no increase was observed in either group (P not significant for normal versus high cholesterol diet). Endocardial flow reserve in the stenosis zone was exhausted in both groups. Epicardial flow in the stenosis zone increased significantly in the normal (P < 0.02) but not in the hypercholesterolaemic animals (P not significant). 4. The endocardial/epicardial ratio in the control zone at baseline revealed greater endocardial dominance in the normal compared with the hypercholesterolaemic animals (1.35 versus 1.10, P < 0.01). With papaverine, similar ratios indicated a similar reserve potential in both groups. During increased oxygen demand, normal animals continued to demonstrate endocardial dominance whereas it diminished in the hypercholesterolaemic group. In the stenosis zone, endocardial blood flow dominated at baseline in the normal animals and to a lesser extent in the hypercholesterolaemic animals (1.30 versus 1.10, P = 0.10). During increased oxygen demand, endocardial dominance decreased significantly in both groups of animals; however, it remained greater than 1.0 only in the normal animals. 5. Exposure to elevated cholesterol levels did not impair an animal's ability to augment coronary blood flow in response to an increase in oxygen demand. In contrast to this lack of effect on recruitment of coronary reserve, regional coronary blood flow was altered in the hypercholesterolaemic animals.

Daily and hourly temporal association between Δ 4-androstenedione - induced preterm myometrial contractions and maternal plasma estradiol and oxytocin concentrations in the 0.8 gestation rhesus monkey

OBJECTIVE: Our purpose was to investigate the temporal relationship between Δ 4-androstenedione-induced preterm switching of myometrial activity patterns from contractures to contractions and maternal plasma estradiol and oxytocin concentrations in the 0.8 gestation rhesus monkey. STUDY DESIGN: Eight rhesus monkeys (132 to 136 days' gestation) were instrumented under halothane with femoral artery and vein catheters and uterine electromyogram electrodes. At 138 to 142 days' gestation baseline maternal femoral artery blood samples for estradiol and oxytocin measurement were taken at 30-minute intervals for 7 hours, starting 2 hours before the onset of darkness. The day after baseline sampling a continuous intravenous Δ 4-androstenedione infusion (0.3 mg · kg -1 · hr -1 in 10% intralipid at 0.25 ml · hr -1) was started in four monkeys, while four monkeys were infused intravenously with intralipid alone. The sampling regimen was then repeated at 1 and 3 days after the start of the Δ 4-androstenedione or intralipid infusion. Contractions were counted and estradiol and oxytocin were measured by radioimmunoassay. RESULTS: Androstenedione promoted a premature nocturnal increase in myometrial contractions in conjunction with an increase in maternal plasma concentrations of estradiol and oxytocin, which were of similar magnitude to those measured in spontaneous term labor. The increase in maternal estradiol preceded the increase in maternal oxytocin levels and myometrial contractions. The onset of the increase in maternal plasma oxytocin was closely associated with the appearance of myometrial contractions after Δ 4-androstenedione treatment. In contrast, no sustained premature contractions or changes in estradiol and oxytocin occurred in intralipid-treated monkeys. CONCLUSIONS: We conclude that in the 0.8 gestation rhesus monkey (1) the increase in maternal plasma estradiol precedes the increase in maternal plasma oxytocin after Δ 4-androstenedione treatment and (2) Δ 4-androstenedione-induced preterm myometrial contractions are closely associated in time with physiologic increases in maternal plasma oxytocin concentrations. (A M J O BSTET G YNECOL 1996;174:1050-5.)

Poor glycemic control induces hypertension in diabetes mellitus.

We conducted this study to test the hypothesis that hypertension is a primary consequence of poor glycemic control per se very early in insulin-dependent diabetes mellitus. Sprague-Dawley rats (n=15) were instrumented with artery and vein catheters, placed in metabolic cages, and sodium intake was clamped throughout the study. Mean arterial pressure was measured 24 h/d. After a precontrol period, streptozotocin (70 mg/kg IV) was administered, and 15 hours later a continuous intravenous infusion was begun at 4 U/rat per day. The insulin infusion was titrated on an individual rat basis to maintain good glycemic control, and after this 7-day control period, blood glucose, urinary sodium excretion, and mean arterial pressure were not different from precontrol values, averaging 8.8 +/- 0.6 mmol/L, 2.8 +/- 0.2 mmol/d, and 103 +/- 2 mm/Hg, respectively, for control days 5 through 7. Subsequently, a 4-day period of poor glycemic control was initiated by reducing the insulin infusion rate. Blood glucose, urinary sodium excretion, and mean arterial pressure began to increase on day 1; for diabetes days 3 and 4, they averaged 23.4 +/- 1.0 mmol/L, 3.6 +/- 0.1 mmol/d, and 110 +/- 2 mm Hg, respectively. All were significantly elevated. When insulin treatment was restored, all variables returned to control levels during the next 4 days. A second 4-day diabetic period yielded similar results. These results indicate that elevated blood pressure is a primary consequence of poor glycemic control in insulin-dependent diabetes, occurring before renal injury has had time to develop, and therefore, may be a factor contributing to the initiation of end-organ injury.

Adipose tissue metabolism in humans determined by vein catheterization and microdialysis techniques

Adipose tissue metabolism in humans determined by vein catheterization and microdialysis techniques

Systemic and diaphragmatic oxygen delivery-consumption relationships during hemorrhage.

When tissue O2 delivery falls below a critical threshold, tissue O2 uptake (VO2) becomes limited. We compared critical O2 delivery and critical and maximum O2 extraction ratios of the resting and contracting left hemidiaphragm with those of nondiaphragmatic tissues in seven dogs. The left hemidiaphragm was perfused through the left inferior phrenic artery with blood from the left femoral artery. Phrenic venous blood was sampled through a catheter in the inferior phrenic vein. Systemic O2 delivery was reduced in stages by controlled hemorrhage. Left diaphragmatic VO2 during rest and during 3 min of continuous stimulation (3 Hz) of the left phrenic nerve and VO2 of the remaining nonleft hemidiaphragmatic tissues were measured at each stage. Critical diaphragmatic O2 delivery for the resting diaphragm averaged 0.8 +/- 0.16 ml.min-1.100 g-1 with a critical O2 extraction ratio of 65.5 +/- 6%. In the contracting diaphragm, they averaged 5.1 +/- 0.9 ml.min-1.100 g-1 and 81 +/- 5%, respectively. Whole body O2 delivery at which resting diaphragmatic VO2 became supply limited was similar to that for nondiaphragmatic tissues. By comparison, supply limitation of VO2 occurred at a higher systemic O2 delivery in the contracting diaphragm than in the rest of the body despite the increase in critical diaphragmatic extraction ratio. Thus, oxygenation of the isolated diaphragm does not appear to be preferentially preserved during generalized reductions in O2 delivery. These results suggest that, in diseases associated with increased work of breathing and decreased O2 delivery, the diaphragm may become metabolically impaired before limitation of VO2 is observed systemically.

Intravenous administration of cocaine stimulates gravid baboon myometrium in the last third of gestation

OBJECTIVE: The hypothesis for this investigation was that intravenous cocaine results in a dose-dependent increase in myometrial activity of the unanesthetized, chronically instrumented gravid nonhuman primate. STUDY DESIGN: Seven chronically instrumented gravid baboons were individually caged in an environment of 14 hours of light and 10 hours of darkness. Maternal femoral artery and vein catheters and three pairs of myometrial electromyographic wires were surgically placed at 90 to 121 days' gestation (term 180 days). At least 5 days after surgery, bolus intravenous cocaine hydrochloride doses of 0.05, 0.1, 0.3, 0.5, and 1.0 mg/kg maternal body weight were administered according to various schedules. Myometrial activity was analyzed by quantifying the myometrial electromyographic envelope data as the power spectral density window of contraction activity and as the total area under the rectified electromyographic voltage signal (i.e., total electromyographic activity) before and during the experimental period. RESULTS: Myometrial contraction activity increased after the 0.3 mg/kg dose (p < 0.01), the 0.5 mg/kg dose (p < 0.005), and the 1.0 mg/kg dose (p = 0.07) compared with baseline. The total myometrial electromyographic activity also increased as the cocaine dose increased. CONCLUSION: Intravenous cocaine results in increased myometrial contractions in the gravid baboon during the latter third of pregnancy. (AM J OBSTET GYNECOL 1994;170:1416-20.)

Intravenous administration of cocaine stimulates gravid baboon myometrium in the last third of gestation

<b>OBJECTIVE:</b> The hypothesis for this investigation was that intravenous cocaine results in a dose-dependent increase in myometrial activity of the unanesthetized, chronically instrumented gravid nonhuman primate. <b>STUDY DESIGN:</b> Seven chronically instrumented gravid baboons were individually caged in an environment of 14 hours of light and 10 hours of darkness. Maternal femoral artery and vein catheters and three pairs of myometrial electromyographic wires were surgically placed at 90 to 121 days' gestation (term 180 days). At lesat 5 days after surgery, bolus intravenous cocaine hydrochloride doses of 0.05, 0.1, 0.3, 0.5, and 1.0 mg/kg maternal body weight were administered according to various schedules. Myometrial activity was analyzed by quantifying the myometrial electromyographic envelope data as the power spectral density window of contraction activity and as the total area under the rectified electromyographic voltage signal (Le., total electromyographic activity) before and during the experimental period. <b>RESULTS:</b> Myometrial contraction activity increased after the 0.3 mg/kg dose (<i>p</i> < 0.01), the 0.5 mg/kg dose (<i>p</i> < 0.005), and the 1.0 mg/kg dose (<i>p</i> = 0.07) compared with baseline. The total myometrial electromyographic activity also increased as the cocaine dose increased. <b>CONCLUSION:</b> Intravenous cocaine results in increased myometrial contractions in the gravid baboon during the latter third of pregnancy.

Exercise-induced fall in insulin: mechanism of action at the liver and effects on muscle glucose metabolism

To determine the importance of the fall in insulin on whole body glucose fluxes and muscle glucose metabolism during exercise, dogs ran on a motorized treadmill for 90 min at a moderate work rate with somatostatin (SRIF) infused to suppress insulin and glucagon and basal (B-INS; n = 6 dogs) or exercise-stimulated (S-INS; n = 8 dogs) insulin replacement. The fall in insulin during exercise potently stimulates glucose production at least in part by potentiating the actions of glucagon. To assess the hepatic effects of insulin in the absence of its potentiating effect on glucagon action, glucagon levels were not restored during SRIF infusion. At least 17 days before experimentation, dogs underwent surgery for chronic placement of sampling (carotid artery and femoral vein) and infusion (inferior vena cava and portal vein) catheters. Hindlimb blood flow was assessed by placement of a Doppler flow cuff on the external iliac artery. Whole body glucose production (Ra) and disappearance (Rd) were assessed with [3-3H]glucose, and hindlimb glucose uptake and metabolism were assessed with arterial-venous differences and [U-14C]glucose. Insulin levels were 69 +/- 6 and 61 +/- 7 pM at rest in B-INS and S-INS and 62 +/- 10 and 41 +/- 6 pM at 30 min of exercise. Glucose levels were clamped at euglycemic levels with an exogenous glucose infusion during rest and exercise in both groups. Exercise-induced increases in Ra, Rd, hindlimb glucose uptake, and hindlimb oxidative and nonoxidative glucose metabolism were not affected by maintenance of basil insulin levels during exercise.(ABSTRACT TRUNCATED AT 250 WORDS)

The Relationship Between the Thrombotic and Infectious Complications of Central Venous Catheters

To assess the frequency of thrombotic and infectious complications of long-term use of vascular catheters in cancer patients and to determine whether the two types of complication are related. Case series. A 500-bed tertiary cancer center. Seventy-two cancer patients. During a 16-month period, postmortem examinations of catheterized veins and contralateral uncatheterized veins were done on all patients with indwelling central venous catheters who met study criteria. Catheter-related septicemia determined by clinical and microbiological data as well as postmortem pathology; venous pathological changes such as mural hemorrhage, thrombosis, calcification, ulceration, and inflammation. Premortem clinical and microbiological data were obtained retrospectively on all patients. Pathological changes were noted in 35 catheterized veins (49%) compared with five contralateral control veins (9.2%) (P < .001). Mural thrombi were noted in 27 catheterized veins (38%) compared with only one contralateral control vein (1.4%) (P < .001). Other pathological changes consisted of four central venous catheter-related mural thrombi (5.6%) in the right atrium and four instances (5.6%) of nonbacterial thrombotic endocarditis, three involving the tricuspid and one the mitral valves. Seven patients had catheter-related septicemia. Of the 31 patients with mural thrombosis of the catheterized vein or right atrium, seven developed catheter-related septicemia, whereas none of the 41 patients with normal catheterized veins and atria developed catheter-related septicemia (P < .01). Thrombotic complications are common in catheterized veins and are often associated with catheter sepsis.

Adipose tissue metabolism in humans determined by vein catheterization and microdialysis techniques

A technique for catheterization of a vein draining abdominal subcutaneous tissue and a microdialysis technique that allows measurements of intercellular water concentrations in adipose tissue in humans have recently been described. In the present study, we compare the two techniques during an oral glucose load. In addition a technique using microdialysis for measurement of tissue oxygen and carbon dioxide tensions is described. Microdialysis and vein catheterization were performed in the same region on the abdomen, and the subcutaneous adipose tissue blood flow was measured by the local 133Xe washout method. The results show that subcutaneous adipose tissue gas tensions are on level with gas tensions measured in abdominal venous blood. Comparison of metabolite concentrations measured in the venous blood and venous blood concentrations calculated from microdialysis data shows that there is good agreement between the concentrations obtained by the two techniques with respect to glucose and glycerol, whereas lactate concentrations are very different. With regard to substrate fluxes calculated by Fick's principle, the catheterization technique is probably the most reliable, considering the numerous assumptions on which calculations of venous concentrations from microdialysis data are based. Advantages and disadvantages of the two techniques are discussed.

Plasma 3 beta-hydroxy-delta 5-steroids in patients with congenital adrenal hyperplasia due to 21-hydroxylase deficiency.

There is little information about the plasma concentrations of 3 beta-hydroxy-delta 5-steroids (delta 5-steroids) in untreated patients with congenital adrenal hyperplasia due to 21-hydroxylase deficiency. To further study the delta 5 pathway, we measured plasma levels of delta 5- and delta 4-steroids in 21 adult patients with different degrees of 21-hydroxylase deficiency (11 salt-wasters, 5 simple virilizers, and 5 patients with the nonclassical form of the disease). In all patients, investigations were performed after withdrawal of steroid treatment for at least 10 days. In addition, catheterization of gonadal and adrenal veins was performed in two salt-wasting male patients displaying bilateral testicular tumors to study adrenal secretion of delta 5- and delta 4-steroids. In one of them, surgical resection of the intratesticular adrenal rests gave the opportunity to measure 3 beta-hydroxysteroid dehydrogenase (3 beta HSD) activity. In all untreated patients, an increase in plasma delta 4-steroids was observed. In contrast, although plasma levels of dehydroepiandrosterone (DHEA) and dehydroepiandrosterone sulfate (DHEAS) were not significantly modified in simple virilizers, a paradoxical decrease in all delta 5-steroids was observed in salt-wasters. Catheterization of the adrenal veins confirmed the decrease in delta 5-steroids, particularly DHEA and DHEAS. The androstenedione/DHEA ratio was increased in all patients proportionally to the severity of the disease, suggesting an increase in adrenal 3 beta HSD. In vitro analysis of 3 beta HSD activity showed a 4-fold increase in intratesticular adrenal tissue compared to that in normal adrenals. A positive correlation between the androstenedione/DHEA ratio and plasma ACTH levels was observed, suggesting a long term stimulatory effect of ACTH on 3 beta HSD. Angiotensin-II could have an additive effect on ACTH-induced 3 beta HSD activity.

Internal Jugular Vein Catheterization under Echographic Guidance

Having examined the various disadvantages of the catheterization of the central veins performed using the Seldinger technique, we report our results of internal jugular vein catheterization under echographic guidance in 38 uremic patients. The echographic guidance technique allows an easier and safer utilization of the internal jugular vein as vascular access in emergency situations.