The combined method: a novel access technique for fetal endoscopic surgery

BACKGROUND/PURPOSE: To develop practical and less invasive techniques for fetal endoscopic surgery, new methods of lifting the uterine wall to allow fetal surgery without maternal laparotomy were developed and assessed. METHODS: Fetal endoscopic surgical procedures, including tracheostomy and umbilical vascular cannulation, were performed using one of the three methods to enter the uterus without maternal laparotomy in pregnant goats (n = 6; 105 to 115 days' gestation): (1) direct uterine lifting with an air-cushion device; (2) indirect uterine lifting, in which the uterine wall was fixed to the maternal abdominal wall using balloon tip ports inserted percutaneously by Seldinger's method, then the maternal abdomen was lifted mechanically; and (3) combined method, in which low pressure CO2 (5 mm Hg for initial inflation and 2 mm Hg for maintenance) was insufflated into the uterus in addition to the indirect uterine lifting cited above. RESULTS: The direct uterine lifting caused massive injury of myometrium and uterine membranes. The creation of intrauterine space and the protection of the membranes were not accomplished effectively by the indirect uterine lifting only. The combined method provided the adequate intrauterine space and excellent endoscopic visibility for completion of the endoscopic procedures with minimal uterine injury. CONCLUSION: The fetal endoscopic surgery may be accomplished simply and safely by the combined method, a novel technique of uterine lifting to allow fetal surgery without maternal laparotomy.     

A sonographically guided technique for central venous access

OBJECTIVE: The internal jugular vein (IJV) is an important access to the central venous system. We compared sonographically guided technique with the traditional anatomic landmark technique for IJV catheterization. SUBJECTS AND METHODS: In a prospective randomized trial, 100 patients underwent routine catheterization of the IJV (50 patients in the sonography group and 50 patients in the anatomic landmark group). Access time, failure rates, and complication rates were evaluated. In addition, the physicians' number of years of experience with catheter insertion was recorded. RESULTS: Access time was markedly shorter with the sonographically guided technique (mean, 15.2 sec; range, 8-76 sec) than with the anatomic landmark technique (mean, 51.4 sec; range, 3-820 sec) (p = .001). The failure rate was significantly lower with the sonographically guided technique (p = .002). Complications were fewer with the sonographically guided technique (neck hematoma, 2% versus 10%; plexus irritation, 4% versus 6%; carotid artery puncture, 0% versus 12%). We found that the number of years of postgraduate clinical training was greater in the group of physicians using the anatomic landmark technique. CONCLUSION: The sonographically guided technique is associated with less risk and less inconvenience for patients, especially critically ill patients, for whom the technique provides fast, safe, and easy IJV catheterization.     

A novel organotypic long-term culture of the rat hippocampus on substrate-integrated multielectrode arrays

Spatiotemporally coordinated activity of neural networks is crucial for brain functioning. To understand the basis of physiological information processing and pathological states, simultaneous multisite long-term recording is a prerequisite. In a multidisciplinary approach we developed a novel system of organotypically cultured rat hippocampal slices on a planar 60-microelectrode array (MEA). This biohybrid system allowed cultivation for 4 weeks. Methods known from semiconductor production were employed to fabricate and characterize the MEA. Simultaneous extracellular recording of local field potentials (LFPs) and spike activity at 60 sites under sterile conditions allowed the analysis of network activity with high spatiotemporal resolution. To our knowledge this is the first realization of hippocampus cultured organotypically on multi-microelectrode arrays for simultaneous recording and electrical stimulation. This biohybrid system promises to become a powerful tool for drug discovery and for the analysis of neural networks, of synaptic plasticity, and of pathophysiological conditions such as ischemia and epilepsy.     

A novel technique for containerless protein crystallization

Heterogeneous nucleation, which is often detrimental to the production of suitable crystals for X-ray diffraction, can be induced by the contact of a crystallization sample with the walls of its supporting vessel. A novel method for creating a 'containerless' environment for the growth of protein crystals is described. Contact between the container walls and a crystallization drop is eliminated by suspending the drop between two oils of different density: one of higher and the other of lower density than that of water and the common precipitating agents. A number of proteins were crystallized in 2-10 microliters drops using this procedure. It was found that the number of crystals obtained in such suspended drops was reduced significantly compared with the number of crystals obtained in trials where the crystallization drop was situated at the bottom of a vial under a single layer of oil. This method has potential in controlling heterogeneous nucleation.     

Reduction of stomach ulceration by hypothalamic stimulation in the unrestrained rat

A rechargeable demand pulse generator for permanent transvenous cardiac pacing was evaluated in 66 patients. During a cumulative follow-up period of 895 patient months there was no instance of failure of either the pulse generator or of the recharging circuit. Acceptance of the recharging concept was high, there being only one patient in whom it was necessary to replace the rechargeable generator because of inability to master the recharging technique. The early findings indicate that with proper patient selection the rechargeable pulse generator promises to be an important contribution to pacemaker therapy.     

Perioperative considerations of vascular access for dialysis

Perioperative nurses can be advocates for dialysis patients by being knowledgeable about various access routes, advantages and disadvantages of each, and associated nursing care. The longevity of vascular access devices depends on avoiding infection and blood clot formation. Perioperative nurses need to assess the knowledge level of the dialysis patient before surgical intervention in any situation.     

Novel vascular sealing device for closure of percutaneous vascular access sites

To investigate the hemostatic capabilities of a novel vascular sealing device consisting of a balloon catheter and procoagulant, vascular sheaths were placed percutaneously in the femoral arteries of dogs. The sealing device was evaluated using the balloon catheter alone in six femoral arteries and with the addition of a procoagulant, in 21 femoral arteries. The balloon catheter alone was successfully deployed in six of six femoral arteries achieving immediate hemostasis. In a second study in which the procoagulant was delivered following balloon placement, the sealing device was successfully deployed and hemostasis was achieved in 20 of 21 attempts (95%) despite removal of the balloon catheter. In a subset of fully anticoagulated animals, hemostasis was achieved in the sealing device-treated arteries at 6.5+/-3.4 minutes, but in none of the controls (P < 0.001). This novel vascular sealing device successfully achieves rapid hemostasis in normal and anticoagulated dogs following percutaneous vascular procedures.     

Arteriovenous fistula. Vascular access for long-term hemodialysis

Long-term hemodialysis remains the most important support for patients with ESRD, and reliable vascular access is an essential component of this management plan. Recent refinements in AV fistula surgical techniques have produced this dependable, well-tolerated, long-term access route for hemodialysis.     

A brief history of vascular access for hemodialysis: an unfinished story

In the recent literature an inverse relationship between iron status and serum aluminum levels has repeatedly been reported in dialysis patients. To check whether this observation is, at least in part, due to an interference of iron with the protein binding of aluminum, we studied the effect of the latter element on both the number of free binding sites on transferrin (Tf) and on the affinity of the protein for aluminum. For the purpose of this, a recently developed HPLC-ETAAS hybrid method was used, allowing protein-binding studies at clinical relevant metal concentrations and under contamination-free conditions. After we incubated apo-Tf with iron and aluminum which were added in amounts equivalent to the calculated number of metal-binding sites on the protein (i.e., 2 mol metal/mol Tf), we found that Tf can be saturated for 100% with iron. However, for aluminum only a 23% aluminum-Tf saturation was observed. In Tf solutions with iron saturations ranging between 0 and 60% as well as in the serum of 15 subjects with iron-Tf saturations varying between 12 and 48%, a significant (p < 0.001) negative correlation between the degree of iron-Tf saturation and the percentage of aluminum (added in amounts equivalent to the number of the remaining binding sites on Tf) bound to Tf was noted (y = -0.26x + 24.5, r = -0.87 in serum). It is concluded that the iron-Tf saturation influences the Tf binding of aluminum not only by occupying binding sites otherwise available for aluminum, but also by lowering the affinity of Tf for aluminum. The effects of iron on serum aluminum levels and bone aluminum deposition are discussed.     

A biotelemetry system for monitoring heart rates in unrestrained ungulates

An EKG telemetry system has been designed for use on free-living ungulates. An FM transmitter with a battery life of 2 +/-0.5 months and a range of 2-6 km is mounted on the back of the animal by means of an adjustable harness. The EKG signal is detected by subdermal electrodes overlying the sternum and transmitted to an FM receiver equipped with a frequency down-converter. The output of the receiver is the modulated audio carrier which is recorded on magnetic tape. The EKG waveform is recovered from the tape-recorded signal using an FM demodulator connected to a strip chart recorder.     

A technique for chronic intermittent bile collection from the rat

A technique is described for inserting into the bile duct, a re-entrant cannula with a sampling arm to allow intermittent collections of bile from unanaesthetised, minimally restrained rats, for a period of 30 days or more. The flow rate of bile (5.38+/-0-25 cm3/h/kg) was higher than that previously reported when using simple or re-entrant cannulas. This higher flow rate may be a result of allowing a minimum of 10 days post-operative recovery period before starting collection of bile and of avoiding anaesthesia and other stresses at the time of collection.     

Subparietal hepaticojejunal access loop for the long-term management of intrahepatic stones

BACKGROUND: The subparietal hepaticojejunal biliary access loop is a recognized technique for the long-term management of primary intrahepatic stone disease. This paper assesses the results of this approach in a series of South African patients. METHODS: Between 1985 and 1997, 21 patients, of mean age 34 (range 24-66) years, underwent surgical extraction of intrahepatic stones and formation of an hepaticojejunal access loop. The access loop was subsequently used for further stone removal and stricture dilatation. Patients were followed prospectively (median 47 months) and details of the number and type of procedures performed, stone clearance rates, morbidity and subsequent outcome were recorded. RESULTS: The distribution of intrahepatic stones was left lobe in 13 of 21 patients, right lobe in one and bilateral in seven. Six patients underwent additional left lobectomy at the initial operation because of associated atrophy of the left lobe. Following operation, stone removal and/or stricture dilatation was performed on 97 occasions (median 4 (range 0-24) procedures per patient). Complete stone clearance was achieved in 17 of 21 patients with partial clearance in the remaining four. There were no major complications and no deaths associated with the procedures. CONCLUSION: The subparietal access loop permits long-term access to the intrahepatic ducts allowing removal of stones and dilatation of strictures with minimal patient discomfort and low morbidity.     

Ultrasound-guided cannulation versus the landmark-guided technique for acute haemodialysis access

BACKGROUND: The correct placement of large-bore venous catheters plays an important role in the management of haemodialysis patients. Whilst the procedure for landmark-based placement of these catheters is well known, the technique is not without significant morbidity and mortality. Complications include arterial puncture, haematoma, and pneumothorax. The procedure may be further complicated in these patients by venous thrombosis and abnormal vein position from multiple previous attempts at venous access. METHODS: Data on the use of ultrasound guidance versus anatomical landmarks for the placement of internal jugular vein (n = 69) and femoral vein (n = 30) dialysis access was retrospectively analysed over a 13-month period. Data collected included age, sex, duration on dialysis, number of vein cannulation sets required, number of attempts for successful cannulation, salvage of failed cannulation using landmark-based technique by ultrasound guidance, and the complication rate. RESULTS: Internal jugular vein cannulation using ultrasound was ultimately successful in 96.7% compared to 82% in the landmark group. The vein was entered on the first attempt in 83.3% of patients with ultrasound compared to 35.9% of the landmark group (P < 0.0001). Seven patients in whom the landmark technique was unsuccessful had access placed under ultrasound guidance. There were fewer carotid artery punctures in the ultrasound group (7.7 versus 0%, P = n.s.). In the femoral vein group, the vein was entered on the first attempt in 85.7% of patients with ultrasound compared to 56.25% of the landmark group (P = n.s.). CONCLUSIONS: The use of ultrasound guidance is associated with fewer complications and is more likely to lead to cannulation of the vein at the first attempt in haemodialysis patients.     

A novel, rapid flat-mounting technique for visualizing antibody labeling in the retina

Complete analysis of retinal tissue is difficult because it consists of a thin neural tissue spread across the back of a hemispheric surface. Conventional sectioning in a plane parallel to a central axis of symmetry produces a large number of samples, each containing only a small amount of the tissue of interest. Consequently, quantitative comparison of any feature of interest typically uses a small fraction of the sections from each retina, because analysis of the entire collection of sections is too time consuming. Such a sampling process can lead to misleading or erroneous conclusions. We present a new method which allows complete analysis of the retina using a small number of samples produced by sectioning flattened retinas. This procedure is straightforward as illustrated using an antibody against proliferating cell nuclear antigen (PCNA) to locate dividing cells in the teleost fish retina. Immunocytochemical staining on flat-sectioned retinas was quantified using a computer-based image analysis system. When the cells of interest are randomly distributed, conventional sampling procedures can seriously under- or over-estimate their number. The new technique presented allows significantly more efficient examination and quantification of the entire retina as compared to conventional techniques.     

Transiliac catheterization of the inferior vena cava for long-term venous access in children

In infants and children requiring prolonged, multiple central venous (CV) catheterizations, the superior (SVC) and inferior vena cava may become thrombosed or stenotic, making CV access a difficult problem. Use of the iliac vein may be an acceptable alternative. We report a patient with thrombosis of the SVC in whom the external iliac vein was accessed through a retroperitoneal approach for placement of an implantable port. This technique is easy to perform, and there are no special materials or patient positioning required.