Ultrasonographic measurement of the subclavian vein diameter for assessment of intravascular volume status in patients undergoing gastrointestinal surgery: comparison with central venous pressure.

BACKGROUND: Previous studies have demonstrated that ultrasonographic measurement of the inferior vena cava diameter is a useful tool for the evaluation of intravascular volume status in preoperative patients. However, ultrasonographic measurement of inferior vena cava diameter could be limited by factors including obesity, bowel gas, or complex abdominal wounds. Our study sought to determine whether subclavian vein (SCV) diameter measured by ultrasound correlate with central venous pressure (CVP), as another indicator of intravascular volume status in patients undergoing gastrointestinal surgery. METHODS: Forty patients (American Society of Anesthesiologists I-II) who underwent elective gastrointestinal surgery and 40 healthy volunteers were enrolled in the study. In the patient group, SCV diameters, during both expiration (dSCVe) and inspiration (dSCVi), were measured with ultrasonography before and after fluid resuscitation. Volunteer baseline measurements were conducted without liquid therapy and the subsequent measurement. RESULTS: Forty patients (mean age 46 y; 40% female) and 40 volunteers (mean age 43 y; 45% female) underwent SCV sonographic measurements. The average diameters of the SCVe and SCVi in hypovolemic patients (0.68, 0.48 cm) were significantly lower as compared with the SCVe and SCVi diameters of healthy volunteers (0.92, 0.73 cm), whereas the SCV-collapsibility index (0.35) was higher in the hypovolemic patients as compared with the healthy volunteers (0.20). After fluid resuscitation, the SCVe and SCVi diameters in hypovolemic patients (0.88, 0.67 cm) significantly increased, whereas the SCV-collapsibility index decreased (0.23). The pre-SCVe and the post-SCVe were closely correlated to the CVP (R = 0.612 and R = 0.547, respectively). Similarly, the pre-SCVi and the post-SCVi were correlated to the CVP (R = 0.452 and R = 0.507, respectively). CONCLUSIONS: SCV diameter is consistently low in patients undergoing gastrointestinal surgery as compared with healthy subjects. Measuring the SCV diameter maybe an important addition to the ultrasonographic evaluation of hypovolemia and other potentially volume-depleted patients.

Comparison of different volumes of saline flush in the assessment of perivenous artefacts in the subclavian vein during cervical CT angiography.

OBJECTIVES: The aim of this study was to examine attenuation values in the central vein and perivenous artefacts at the subclavian vein in cervical CT angiography (CTA) when using 40 ml contrast material (CM) followed by different volumes (25 ml vs 40 ml) of saline flush (SF). METHODS: 61 patients underwent CTA between the aortic arch (AA) and distal to the circle of Willis (cW). After calculating test-bolus time to peak enhancement at the cW (Tc), scanning delay was represented as [(Tc + 4) - scan duration between AA and cW] s. 28 patients (Group A) received 40 ml of 370 mg iodine (I) ml(-1) CM followed by 25 ml of SF, and 33 patients (Group B) received the same CM followed by 40 ml of SF, both administered through the right antecubital vein. Arterial attenuation was measured at seven points in the aorto-carotid artery and at three points in the vertebrobasilar artery. Venous attenuation in the central vein was measured at four points. Mean attenuation values were analysed quantitatively. Axial and post-processing three-dimensional images were assessed qualitatively. RESULTS: When Groups A and B were compared, there were no differences in the mean attenuation values in either the aorto-carotid artery (p=0.78) or the vertebrobasilar artery (p=0.82). Mean venous attenuation values were lower (p=0.002) in Group B than in Group A. Although the qualitative assessment of arterial images showed no differences between the two groups overall, perivenous artefacts at the subclavian vein were assessed as less prominent (p<0.01) in Group B. CONCLUSIONS: When compared with CTA followed by 25 ml of SF, CTA followed by 40 ml of SF can reduce venous attenuation values and perivenous artefacts at the subclavian vein.

[Multislice computed tomographic angiography in the assessment of central veins for endovascular treatment planning: comparison with phlebography]. / Angio-TC MS nello studio dei vasi venosi centrali per la pianificazione del trattamento endovascolare: studio comparativo con la flebografia.

The dysfunction of a vascular access for hemodialysis and its loss may depend on drainage difficulties of the superficial or deep venation due to hemodynamically significant stenosis or obstruction of a central vein, which generally involve the innominate-subclavian veins or superior vena cava. These alterations are often neglected due to their central and deep location; when there is hemodynamic compensation, they may remain asymptomatic. For these reasons every suspect clinical sign for central vein stenosis (gross arm syndrome or venous hypertension in an arteriovenous fistula) must not be ignored, as timely intervention is essential for functional recovery of the vessel and for the protection of the arteriovenous fistula. The modern imaging techniques ensure thorough diagnostic assessment, while the possibilities of endovascular treatment with interventional radiology allow, in a large proportion of cases, optimal minimally invasive treatment, but above all the recovery of venation in a hemodialyzed patient. We report our experience with multislice computed tomographic angiography (MS-CTA) and reconstruction software for treatment planning of central vein stenosis or obstruction. Forty-nine patients were studied with MS-CTA (GE 16). Images were acquired in the venous phase (120-180 seconds after contrast medium injection) followed by digital vascular reconstruction (AutoBone for bone removal, vessel analysis for caliber and length measurements, thin and curved MIP, MPR). Within a week control phlebography was performed. The venous tree was divided into seven segments and analyzed in a double-blind fashion with a distinction between patent segments, 50-70% stenosis, >70% stenosis, occlusion, and collateral vascular beds. There was excellent correspondence in all the examined segments for patency, >70% stenosis, and occlusion, with high sensitivity (98%), specificity (99.3%), and diagnostic accuracy (99.1%). The binomial test demonstrated a highly significant concordance (alpha=0.99) for all patients and in all vascular segments with the exception of 70% stenoses, in which MS-CTA gave a slight overestimate. In the central venous district, color Doppler ultrasonography may not be as effective as for the peripheral study of arteriovenous fistulae, and second-level imaging techniques such as MS-CTA are more useful. We suggest that endovascular treatment must be preceded by MS-CTA. This examination shows the lesions that may benefit from endovascular treatment and recognizes ''uncrossable'' lesions, ie, the ones that will not benefit from treatment. Moreover, it allows accurate planning of endovascular treatment by showing the lesion type (stenosis or obstruction), the position and extension of the involved vessels, the vessel caliber above and below the lesion, and the possible presence of a collateral vascular bed. MS-CTA with dedicated reconstruction software, if correctly performed and accurately reconstructed, is a precious tool for diagnosis and treatment planning.

The incidence and risk of central venous catheter malpositioning: a prospective cohort study in 1619 patients.

Central venous catheters are used in various hospital wards. An anterior-posterior chest X-ray is usually obtained soon after cannulation to assess the location of the catheter tip. This prospective clinical study was designed to determine the radiographic catheter tip position after central venous cannulation by various routes, to identify clinical problems possibly associated with the use of malpositioned catheters and to make a cost-benefit analysis of routine chest X-ray with respect to catheter malposition. A total 1619 central venous cannulations were recorded during a three-year period with respect to patient data, information about the cannulation procedures, the radiographic catheter positions and complications during clinical use. The total incidence of radiographic catheter tip malposition, defined as extrathoracic or ventricular positioning, was 3.3% (confidence interval 25 to 4.3%). Cannulation by the right subclavian vein was associated with the highest risk of malposition, 9.1%, compared with 1.4% by the right internal jugular vein. Six of the 53 malpositioned catheters were removed or adjusted. No case of malposition was associated with vascular perforation, local venous thrombosis or cerebral symptoms. We conclude that the radiographic incidence of central venous catheter malpositioning is low and that clinical use of malpositioned catheters is associated with few complications. However, determination of the catheter position by chest X-ray should be considered when mechanical complications cannot be excluded, aspiration of venous blood is not possible, or the catheter is intended for central venous pressure monitoring, high flow use or infusion of local irritant drugs.

Ultrasound guidance for central vascular access in the pediatric emergency department.

Central vascular access is sometimes required for hemodynamic monitoring and infusion of fluids and medications in the pediatric emergency department. In many cases, it is attempted after failed peripheral venous and intraosseous access. Some evidence exists demonstrating benefits of ultrasound (US)-guided central vascular cannulation in adults in emergency departments. With appropriate education in its use, US-guided cannulation of central veins in children is likely to be associated with less complications and greater success. In the pediatric emergency department, the femoral vein is the most practical central venous cannulation site. A sound educational and quality assurance program is necessary for US-guided cannulation in the pediatric emergency department.

Assessment of the subclavian vein in patients with transvenous pacemaker leads.

Thrombosis of the subclavian vein can occur after the implantation of transvenous pacemaker electrodes. Although this is seldom followed by thromboembolic complications, it can cause problems when replacing the leads. To assess the impact of the pacemaker leads on the subclavian vein, a study using noninvasive duplex sonography was performed on 56 patients at an average of 41 months after the implantation. Forty-three percent of the patients were found to have a normal function of the subclavian vein, 46% developed pathological changes of the vessel wall, and 11% occluded. These changes rarely caused symptoms, and, therefore, had little clinical significance. Moreover, the occlusion rate was found independent of the patient's age, the patient's sex, the number of electrodes, the procedure of implantation, and even the time from implantation. As a result, the clinical diagnosis of occlusion is uncertain. Therefore, duplex sonography is recommended as an easy means of excluding a totally thrombosed subclavian vein prior to replacing pacemaker leads.

[Vein patency in patients with pacemaker implanted via subclavian vein: digital phlebography assessment]. / Pervietà venosa nei pazienti con pacemaker impaintati per via succlavia: controlli con flebografia digitalizzata.

Venous thrombosis is a well-known complication of permanent cardiac pacemaker implantation, particularly, chronic occlusion of the subclavian vein is reported to occur in 20-33% of the cases where the percutaneous approach is performed. We examined 135 asymptomatic patients with digital venography to asses the frequency of venous thromboses causing stenosis and occlusion of the subclavian or anonymous arteries in pacemaker carriers. We considered both one- (44) and two-chamber (91) pacemakers and investigated a possible statistically significant difference between them: we found 21 venous thromboses (15%), seven of them in one-chamber pacemakers (15.9%) and 14 two-chambers pacemakers (15.3%). None of our 94 male and 41 female patients was on anticoagulants or had any evidence of coagulation disorders. Venography was performed 39.3 months (mean) after pacemaker implantation (range: 3-120 months). We conclude that digital venography is a simple and relatively noninvasive method permitting better depiction of subclavian, anonymous and caval veins than Doppler US and also showing some vascular abnormalities which may complicate pacemaker implantation.

Scintigraphic assessment of "effort" axillary-subclavian vein thrombosis.

"Effort" axillary-subclavian vein thrombosis (Paget-Schroetter syndrome) is an uncommon deep venous thrombosis due to repetitive activity of the upper limb. Clinical suspicion is usually confirmed by contrast venography. This report describes a case where the diagnosis was made by radionuclide venography (Tc-99m DTPA). The examination was carried out in the acute phase and clearly demonstrated the presence and the site of the obstruction as well as the collateral vessels. Despite a complete clinical recovery, obtained by medical therapy, further examinations performed in the follow-up period showed persistence of the thrombotic obstruction and a rich development of collateral vessels. In the authors' opinion, radionuclide venography is worth considering as a first-choice procedure when an axillary-subclavian vein thrombosis is suspected, and contrast venography should be performed only when surgical treatment is indicated.

Implantofix vascular access system: an experience with 19 patients.

The use of implantable vascular access devices has increased rapidly in recent years. We have placed the new Implantofix Implantable Drug Delivery System 7500 in 19 patients. The patients reported only minor discomfort. The majority of the nurses found the Implantofix port easier to access than other ports, and some reported less swelling and soreness at the port site. Some of the physicians had difficulty visualizing the radiopaque catheter on X-ray; Burron is currently developing a more radiopaque system. The Implantofix system offers several important benefits. Its compact size assures minimal discomfort for the patient. A new peel-away sheath offers a choice of insertion methods. The system is particularly economical because it can be implanted in an ambulatory care facility or an outpatient surgery room equipped with fluoroscopic capabilities.

Radiographic assessment of venous catheter position in children: value of the lateral view.

Frontal chest radiographs can be misleading in the evaluation of central venous catheter placement. Lateral chest radiographs were obtained, in addition to the standard frontal radiographs, in 25 young children. In five (20%) of the children, the catheters were found to be malpositioned, and the frontal radiograph showed evidence of the abnormality in all five. The lateral radiographs also showed evidence of the abnormality in all five children; however, in three of the five, the lateral radiographs provided additional, more specific, diagnostic information. The lateral chest radiographs also demonstrated satisfactory catheter positioning in three other children in whom the frontal radiographs suggested abnormal positioning. Accurate assessment of catheter position was possible in all patients using both frontal and lateral chest radiographs. Injection of contrast material was not necessary to locate malpositioned catheters. Lateral radiographs are recommended whenever an abnormal catheter position is suspected clinically or from findings on the routine frontal radiograph.

[Phlebography of the upper extremity: assessment of various x-ray signs]. / Die Phlebographie der oberen Extremität: Wertung verschiedener Röntgensymptome.

The article reports on the findings obtained in 56 serial phlebographies of the upper extremity. Using 17 phlebographies without pathological findings as basis, the physiological phenomena of venous contrasting in the region of the shoulder and arm are examined. The remaining phlebograms with pathological findings are assessed according to different criteria, such as localisation and extent of venous vascular occlusion, visualisation of vascular clot and formation of collaterals resulting in collateral circulation.

Roentgenographic assessment of causes of cardiac pacemaker failure and complications.

Implantation of a permanent pacemaker to stimulate the heart is a well established procedure of great benefit. However, a malfunctioning pacemaker is a hazard to well-bing and to life. Once a pacemaker has been installed the physician's attention is directed not only to the patient's illness but also the unique complications of cardiac pacemakers. Roentgenograms are a valuable resource in the assessment of patients with pacemakers. It is essential that the radiologist thorougly understand the extent to which radiologic studies can depict the functioning of the complications associated with pacemakers. The roentgenographic assessment of the causes of pacemaker failure and the complications associated with permanent pacemakers are reviewed and the role of the roentgenogram is defined.