OBJECTIVE: To determine whether stopping nitroglycerin and sodium nitroprusside (both vasodilators) infusions in hypertensive, postcardiac surgical patients requiring a high FIO2 improves PaO2 and venous admixture. DESIGN: Prospective, clinical trial. SETTING: Intensive care unit in a university-affiliated hospital. PATIENTS: Thirty postcardiac surgical patients who, because of high FIO2 requirements, did ...

In spite of its invasiveness, measurement of ambulatory venous pressure (AVP) is widely considered the gold standard measurement of venous function. We studied a technique for noninvasive ultrasonographic AVP determination in superficial venous incompetence. A linear relationship between venous pressure (measured by echo-guided venous puncture) and diameter (measured by transverse ...

BACKGROUND: Elastic compression stockings are widely used medical devices for the prevention of edema and treatment of venous diseases. Many beneficial effects have been described in the past. The exact amount of pressure underneath elastic compression stockings at different areas of the leg remains controversial. OBJECTIVE: To examine the pressure ...

OBJECTIVES: Increased activity of pro-inflammatory cytokines in the circulation has been observed in many, though not all, patients with congestive heart failure. To identify the predictors of cytokine activation in congestive heart failure, we assessed the relationship of peripheral and hepatic venous cytokines to central haemodynamics, neuroendocrine status and intermediary ...

The hypothesis was tested that the abdominal area constitutes an important reservoir for central blood volume expansion (CBVE) during water immersion in humans. Six men underwent 1) water immersion for 30 min (WI), 2) water immersion for 30 min with thigh cuff inflation (250 mmHg) during initial 15 min to ...

1. Venous congestion strain-gauge plethysmography enables the non-invasive assessment of arterial blood flow, fluid filtration capacity (Kf), venous pressure (Pv) and isovolumetric venous pressure (Pvi) in man. One of the major assumptions of this technique, that cuff pressure (Pcuff) applied to the limb equals Pv at the level of the ...

A potentially attractive support device for patients with acute respiratory failure is an intravenous membrane oxygenator. One problem, however, is that the membrane surface area required for sufficient gas exchange can unduly increase vena caval pressure drop and impede venous return. The purpose of this study was to design and ...

The aim of the study was to investigate the release of endothelin-1 (ET-1) in normal and varicose saphenous veins at baseline and after venous stasis test. Ten patients (eight women and two men, mean age 43 +/- 4) with primarily varicose great saphenous veins and ten controls (eight women and ...

Thirty adult patients with distal, monolateral deep vein thrombosis of the lower limbs were randomly treated for sixty days either with subcutaneous Ca-Heparin or with Sulodexide, administered IM for ten days and orally for fifty days. The thrombus accretion above the knee, the venous pressures of the affected leg, the ...

OBJECTIVE: To investigate the effect of lightweight graduated elastic stockings on venous haemodynamics. DESIGN: The amount of reflux and function of the calf muscle pump were evaluated before and after the application of lightweight graduated compression stockings using air-plethysmography. Each patient acted as his own control and the Wilcoxon rank ...

OBJECTIVES: To determine whether intra-abdominal pressure (as estimated from urinary bladder pressure) is elevated in patients with central obesity (as measured by sagittal abdominal diameter) and pseudotumor cerebri and whether this increased intra-abdominal pressure is associated with increased pleural pressure and cardiac filling pressure, implying a resistance to venous return ...

The central effects of capsaicin, veratrine, histamine and bradykinin were studied by injecting them directly into the oerebrospinal fluid and their peripheral effects were examined by injecting into femoral vein. Our experiments were performed in Na-pentobarbital-anaesthetized dogs. Tidal volume (VT), respiratory frequency (f/min), systemic arterial pressure (BP) were recorded. A ...

Central venous catheters are commonly used for haemodialysis patients and represent, in our centre, about 15% of the permanent vascular accesses with a total number of more than 230 central venous catheters over the last 10 years. Inadequate blood flow may occur and upsets the nurses, the patients, and the ...

To determine whether changes mixed-venous PCO2 or PO2 affect cardiac output independent of changes in arterial blood gases, we used extracorporeal gas exchange to increase mixed-venous PCO2 or decrease mixed-venous PO2 in adult sheep. Sheep were anesthetized, mechanically ventilated, and connected to a veno-venous extracorporeal circuit. The circuit included a ...

It has been suggested that leukocyte trapping and activation in the microcirculation of the leg skin causes lipodermatosclerosis and ulceration in patients with chronic venous disease. Ambulatory venous hypertension is accepted as the physiologic factor that leads to ulceration. We investigated leukocyte endothelial adhesion in patients who were subjected to ...

Plasma arginine vasopressin (AVP) concentration is reduced in human subjects during prolonged saturation dive exposures of 4 atmospheres absolute (atm abs) and greater. The objectives of the present study were to determine if AVP would be reduced in eight male subjects during a 1-h exposure of 3 atm abs air ...

Measurement of the oxygenation of the peripheral tissues provides useful information about tissue perfusion. A method is described for the measurement of peripheral venous oxyhaemaglobin saturation (SvO2) in the adult forearm by a noninvasive technique, near infrared spectroscopy (NIRS) with venous occlusion. A series of studies is performed on healthy ...

PURPOSE: To determine in-line pressures generated in small-bore central venous catheters during power injection of computed tomographic (CT) contrast media. MATERIALS AND METHODS: Five 3.0-7.0-F central venous catheters for pediatric patients were tested at full and half lengths in vitro. In-line pressures were measured during power injection of three contrast ...

A patient with recurrent acute pancreatitis developed pericardial effusion and cardiac tamponade. His systolic blood pressure fell to 70 mmHg and sinus tachycardia (150/min) developed. The central venous pressure rose from 3 cm H2O to 27 cm H2O. A chest radiograph showed an enlargement of the cardiac shadow. Pericardial paracentesis ...

BACKGROUND: We evaluated the ability of the standards issued by the Danish Society of Anaesthesiologists to reflect a blood loss. METHODS: In 9 pigs bled (0-24 ml kg-1 and retransfused (to 28 ml kg-1) during halothane anaesthesia central cardiovascular, thoracic electrical impedance (TI), oxygen, acid-base and temperature variables were recorded. ...

Venous capacitance plays an important role in the control of cardiac output. However, the central nervous system sites and neurochemical signals involved in modulating venous function remain to be fully elucidated. The hypothalamic paraventricular nucleus (PVN) is an important site modulating autonomic outflow to the cardiovascular system. The present study ...

This study was designed to determine the conditions that promote carbon dioxide embolism after venous injury during laparoscopy in pigs. Injury to an iliac vein was filmed during laparoscopy in the presence of a pneumoperitoneum created at increasing pressures from 0 to 30 mm Hg in 5-mm Hg increments. At ...

Effective peripheral blood flow is positively related to cardiac output and gravity (part dependent) and inversely related to gravity (part elevated), venous pressure, interstitial fluid pressure, degree of peripheral neuropathy, arteriosclerotic and thrombotic arterial obstructions, and infection. These factors are considered in the operation of the end-diastolic pneumatic boot in ...

Venous air embolism (VAE) can be a lethal complication of surgical procedures, during which (1) venous pressure at the site of surgery is subatmospheric or (2) gas is forced under pressure into a body cavity. Though classically associated with neurosurgery, VAE is also a potential complication of laparoscopic, pelvic, and ...

A canine model of cortical vein occlusion was used to evaluate whether data obtained from monitoring venous stump pressure could help predict cerebral infarction after venous obstruction. Following bilateral parasagittal craniotomy, the cortical vein in each hemisphere was temporarily occluded and the increase in pressure was directly measured. Permanent venous ...

Venous bleeding during transsphenoidal surgery for resection of pituitary tumors is a common problem that interferes with the performance of the surgical procedure. In this study, data were collected prospectively from 50 patients to determine whether there were pre- or intraoperative factors (e.g., patient demographics, type and grade of pituitary ...

The aim of this study was the assessment of physiological venous reflexes in open angle glaucoma. The study was carried out by a controlled clinical experiment. The experimental group consisted of 17 glaucoma patients with controlled intraocular pressure. The control group consisted of 15 healthy volunteers. The assessment of venous ...

The currently favoured hypothesis for the link between the raised venous pressure of chronic venous insufficiency and venous ulceration is based on the intermittent inappropriate activation of white blood cells. The damage initiated by the oxidative burst of the leucocyte leads to endothelial dysfunction, interstitial oedema, microthrombi and long-term microcirculatory ...

The arterial, double and venous occlusions are used to partition pulmonary vascular resistance into four segments. In this study, we tested whether the same can be accomplished from one double occlusion. In an isolated canine lung left lower lobe perfused with blood (flow rate = 500 mL.min-1), the pulmonary arterial ...

It has been suggested that hemodynamic instability and impaired vascular reactivity during combined ultrafiltration-hemodialysis are related to bioincompatibility factors such as dialysate-derived contaminants or the dialyzer. The study presented here investigated whether vascular reactivity could be improved by the use of sterile dialysate. Forearm vascular resistance and venous tone (measured ...

OBJECTIVE: To compare two methods, venous dialysis pressure (VDP) and intra-access static flow pressure (VPO), for the prospective identification of venous stenoses in high-risk PTFE grafts. DESIGN: Comparative. SAMPLE/SETTING: Twenty patients with upper extremity loop grafts in an outpatient chronic hemodialysis population. METHODS: VDP and VPO were measured for three ...

Leukocyte trapping and activation in the microcirculation of the legs may play an important role in causing skin damage in venous disease. Leukocyte emigration from the microcirculation and subsequent locomotion in response to venous hypertension was studied in a group of 12 normal volunteers using a "skin window" technique. Two ...

To study the hemodynamic effects of an arteriovenous fistula (AVF) used as an adjunct to venous reconstructions and to determine the optimal size for such a fistula. A model of limb circulation with an AVF (in vitro system) was constructed with silicon elastic tubes and 40% glycerin solution as the ...

Excessive distension of venous grafts due to arterial pressure enhances the convective water transport (filtration flow) through the vessel wall, and thus might affect the infiltration of macromolecules such as lipoproteins. In this paired experimental study, filtration velocities were measured at 100 mm Hg for canine jugular veins with or ...

Compression of the lower extremity is the mainstay of therapy in patients who have chronic venous insufficiency. We evaluated the ability of two forms of compression-elastic stockings and an inelastic compression garment-with air plethysmography to determine how well they corrected abnormal deep venous hemodynamics in patients who had class III ...

We suggest a mechanism by which blood volume changes might explain the hypotension that, after space flight, often accompanies the return to normal gravity. Upon entering microgravity, peripheral veins may collapse and, because of volume redistribution, raise the pressure in the central venous compartment. After some time in space, homeostatic ...

OBJECTIVE: The purpose of this study was to determine if pulsatile flow in lower limbs as seen on venous Doppler waveforms correlates with increased right atrium pressure. MATERIALS AND METHODS: Of 429 patients who, over a 14-month period, underwent venous Doppler imaging of the lower limb to exclude deep venous ...

Oedema remains one of the most common causes of hand stiffness. Local venous return is intimately associated with oedema formation and management. To elucidate the underlying mechanisms of venous return, the venous pumping systems in the hand were objectively and quantitatively investigated using Doppler ultrasound, cadaveric dissection and venography. It ...

BACKGROUND: Although medical elastic compression stockings are widely used in venous diseases their effects on the venous system are still largely unclear. OBJECTIVE: To evaluate the pressure of these medical elastic compression stockings on the skin and their edema protective effects. METHODS: On 18 legs the interface pressure of the ...

In this study, peripheral microcirculatory response to arterial and venous cannulation was studied. Eleven Sprague-Dawley rats were evaluated in two groups. Group I was the control group and received no cannulation (N = 6). After cremaster muscle isolation, the following parameters were evaluated at the microcirculatory level: vessel diameters, red ...

The concept of left ventricular (LV) 'preload' has seemed simple and straightforward. Similarly, the capacitance function of the veins seemed to be defined, in spite of the fact that 'venous return' might be said to be increased in heart failure when it was obvious that cardiac output was substantially decreased. ...

PURPOSE: To determine the feasibility of use of a power injector to deliver contrast material through central venous catheters for computed tomographic (CT) examinations. MATERIALS AND METHODS: Ioversol 240 and iothalamate meglumine 43% were separately injected through three 9.6-F Hickman catheters and three 10.0-F Leonard catheters with a power injector ...

Nitroglycerine relaxes vascular smooth muscle and is routinely use to treat angina and congestive heart failure. However, in preliminary observations of severe heart failure patients, nitroglycerine did not dilate superficial veins, although the observations were made at the top of the distention-pressure relationship for superficial veins. Hence, the purpose of ...

BACKGROUND: Astronauts conducting extravehicular activities undergo decompression to a lower ambient pressure, potentially resulting in gas bubble formation within the tissues and venous circulation. Additionally, exposure to microgravity produces fluid shifts within the body leading to cardiovascular deconditioning. A lower incidence of decompression illness in actual spaceflight compared with that ...

To confirm the hypothesis that venous congestion plays a role in idiopathic lunate necrosis (Kienböck's disease), intraosseous pressure in 12 normal and 12 necrotic lunates was measured. Intraosseous pressure in the capitate of 12 healthy subjects served as reference measurement. The intraosseous pressure was recorded in neutral position and 60 ...

OBJECTIVE: To assess the rate of change in the central retinal venous closing pressure in central retinal vein obstruction over time, and its relationship to visual acuity improvement and the development of rubeosis iridis. METHODS: Fifty patients presenting with central retinal vein obstruction of less than three months' duration, between ...

Based on the results of head-down simulation studies and the results of parabolic flights, the hypothesis was tested that central venous pressure (CVP) in humans increases during microgravity (weightlessness) compared with during the ground-based supine position. CVP was recorded with an intravascular pressure transducer in seven healthy humans during short ...

Gravity affects cardiac filling pressure and intravascular fluid distribution significantly. A major central fluid shift occurs when all hydrostatic gradients are abolished on entry into microgravity (microG). Understanding the dynamics of this shift requires continuous monitoring of cardiac filling pressure; central venous pressure (CVP) measurement is the only feasible means ...

Serum concentrations of rHuEPO were measured after injection into different sites within the blood lines in patients undergoing hemodialysis. The authors compared the venous port to venous drip chamber injection using two separate delivery systems and their associated blood lines (Cobe Centry 3 [CGH, Lakewood, CO] and Fresenius A2008 [Fresenius ...

This study was undertaken to elucidate the still debated question of the relationship between cardiac volume and QRS voltage amplitude. The authors studied 14 healthy men, aged 24-61 years (mean age, 41.2 +/- 12.1 years). They underwent a reduction in venous return, produced by simultaneously inflating sphygmomanometric cuffs placed around ...