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PubMed2000

Growth and determinants of access in patient e-mail and Internet use.

OBJECTIVES: To measure the rate of access to and use of the Internet and e-mail, to determine sociodemographic predictors of access, and to measure the change in Internet and e-mail access over a 1-year interval. DESIGN: Survey study. Comparison of data with those from a similar survey from 1998. SETTING: Emergency department of a large urban pediatric teaching hospital. PARTICIPANTS: Primary caretakers of pediatric patients or the patients themselves if aged 16 years or older. MAIN OUTCOME MEASURES: Use of and access to the Internet or e-mail. RESULTS: We surveyed 214 individuals: 72.8% use or have access to the Internet, e-mail, or both, an increase from 52.2% in the 1998 survey (P<.001), and 48.5% regularly use the Internet or e-mail, compared with 43.1% in 1998 (P = .32). Outside the home, access is primarily at work (52.2%), schools (8.9%), public libraries (11.5%), and friends' and relatives' houses (16.7%). Internet use and access are linearly correlated with income (r = 0.43; P<.001). White patients are more likely to have access (odds ratio, 2.6; 95% confidence interval, 1.3-5.4; P<.001) than black or Asian patients, whereas those of Hispanic ethnicity are less likely to have access (odds ratio, 0.20; 95% confidence interval, 0.09-0.43; P<.001). However, after adjustment for race and Hispanic ethnicity, only income was a significant predictor of family access to the Internet and e-mail. CONCLUSIONS: During the past year, many patients have gained access to the Internet and e-mail, although rates of regular use have remained steady. This access is often from outside the home. Furthermore, access is directly related to income and is unevenly distributed across racial and ethnic groups.

Adolescent↗

PubMed2005

Prospective assessment of hemodialysis access patency after percutaneous intervention: Cox proportional hazards analysis.

Vascular access failure is the greatest limitation of successful hemodialysis, but the factors associated with long-term patency have not been fully elucidated. Outcomes in a consecutive series of 294 thrombosed or failing accesses [128 fistulas (43.5%) and 166 grafts (56.5%) in 179 patients] were analyzed with life table and multivariable Cox proportional hazards analysis. Initial success was achieved in 275 of 294 accesses (95.6%). The median patency after intervention was 206 days (interquartile range, 79-457 days). Fistulas had longer median patency after intervention than grafts (286 vs. 170 days). Nonthrombosed accesses had longer median patency than thrombosed accesses (238 vs. 136 days), but thrombosed fistulas had similar median patency as thrombosed grafts (140 vs. 136 days). The selective use of stents as a bailout for failed balloon dilatation did not significantly reduce long-term patency (196 days for stented accesses vs. 210 days for unstented accesses). Long-term patency was inversely related to final access pressure, but access patency was not related to the presence of central venous occlusions, graft age, patient age, sex, or diabetes. Catheter-based intervention of thrombosed and failing dialysis accesses significantly prolongs patency and usefulness of dialysis accesses. The expanding use of fistulas, improved detection of early access failure, and selective use of bailout stents should enhance long-term access patency.

Arteriovenous Shunt, Surgical↗

PubMed2005

Comparative study of percutaneous access for staghorn calculi.

OBJECTIVES: To compare the success and complication rates of staghorn calculi treated through the upper pole calix, lower/middle calices, and multiple access. METHODS: Between January 1995 and December 2000, the records of 119 patients with staghorn calculi who underwent percutaneous nephrolithotomy were retrospectively reviewed. The mean stone burden was 6.9 cm. Of the 119 patients, 16 (13.4%) had upper pole access, 70 (58.8%) lower or middle calix access, and 33 (27.7%) multiple renal access. RESULTS: The stone-free rate was 80.0% for those in the lower/middle, 87.5% for those in the upper pole, and 84.8% for those in the multiple access group. Single access was performed in 72.3% and multiple access tracts in 27.7% of patients. The average operative time was 86.8 minutes in the upper pole, 139.1 minutes in the lower/middle pole, and 134.9 minutes in the multiple access groups. Extracorporeal shock wave lithotripsy was used in 4.2% of patients. The overall complication rate was 28.5% (25% in the upper pole, 21.4% in the lower/middle, and 45.4% in the multiple access group). Thoracic complications (pneumothorax and hydrothorax) occurred in 2 patients (1.7%), but only 1 patient had undergone supracostal access. Bleeding requiring blood transfusion was significantly greater in the multiple access group. The average hospital stay was 3.0 days for all patients. CONCLUSIONS: The success of percutaneous treatment of patients with staghorn calculi is highly related to optimal kidney access. The supracostal and multiple access approaches can be used, with a slight increase in the incidence of acceptable complications.

Humans↗

PubMed1997

Care pathway reduces hospitalizations and cost for hemodialysis vascular access surgery.

Hemodialysis vascular access-related hospitalizations account for more than 20% of United States end-stage renal disease (ESRD) hospitalizations, with an annual cost approximating $675 million. Limiting access-related costs while delivering similar degrees of quality care thus would enhance alternative utilization of ESRD funding. We implemented a vascular access care pathway emphasizing coordinated patient evaluation and outpatient surgery to determine whether such an intervention affected outcomes associated with vascular access surgery. Data examining hospitalization and vascular access surgery charges, complications, and patient satisfaction (determined by questionnaire) were analyzed, comparing patients who underwent vascular access surgery in 1994 and 1995 as inpatients (non-care pathway patients) and patients who underwent vascular access surgery via the care pathway in 1995. Inpatient days declined in 1995 (1994: 582 days; 1995: 85 days; P < 0.03) and the average charges per patient for the care pathway cohort were significantly less than charges per patient in 1994 and charges for non-care pathway patients in 1995 (1994 patients: $10,524 +/- $5,209; 1995 non-care pathway patients: $11,196 +/- $5,806; 1995 care pathway patients: $4,686 +/- $2,912/patient; P < 0.02). Incidence rates for major (life-threatening) complications were not significantly different between 1994 patients and care pathway patients in 1995. However, the 1995 non-care pathway patients had a higher incidence of major complications (15.4%). Forty-seven repeat access procedures were performed in 29 patients in 1994 versus 35 repeat access procedures in 22 care pathway patients in 1995, and 12 repeat access procedures were performed in eight non-care pathway patients in 1995. Finally, a majority of the patients entered into the care pathway who responded to a survey stated that they were satisfied with access surgery via the care pathway. These data suggest that a vascular access care pathway can reduce hospital days and costs while achieving acceptable outcomes for access surgery.

Ambulatory Surgical Procedures↗

PubMed1999

A practical approach to vascular access for hemodialysis and predictors of success.

PURPOSE: The long-term results and predictors of success for vascular access at The Toronto Hospital were studied. This report describes the access program and emphasizes the role of the vascular access coordinator. METHODS: A total of 384 consecutive patients underwent 466 vascular access procedures. The access program is centered around a dedicated, full-time vascular access coordinator, who is a registered nurse and is responsible for all aspects of access care, including follow-up. Outcome variables were collected prospectively. Primary, primary-assisted, and secondary success was determined by means of Kaplan-Meier analysis, and the stepwise Cox proportional hazards model was used for multivariate analysis of the factors that were independently predictive of primary success. RESULTS: There were 235 autogenous arteriovenous fistulae (AVFs) and 231 arteriovenous grafts (AVGs). The cumulative primary, assisted-primary, and secondary success (patent and functional for effective dialysis) at 24 months for all 466 cases combined was 36% +/- 3%, 54% +/- 3%, and 66% +/- 3%, respectively. The primary success for AVFs and AVGs at 2 years was 54% +/- 4% and 18% +/- 4%, respectively (P <.001; log-rank test); the primary-assisted success for AVFs and AVGs at 2 years was 62% +/- 4% and 44% +/- 6%, respectively (P <.001; log-rank test); and the secondary success for AVFs and AVGs at 2 years was 70% +/- 4% and 60% +/- 5%, respectively (P =.331; log-rank test). Stratification of variables revealed significant benefit for AVFs (P =.001), the female sex (P =.014), and the absence of diabetes mellitus (P =.001). Multivariate analysis with Cox regression determined that access type (AVF vs AVG; P =.001) and diabetes mellitus (P =.024) were independently predictive of primary success. The improved clinical coordination of access patients with the initiation of the vascular access program resulted in a significant reduction in length of hospital stay before and after the program was organized (2.5 +/- 0.06 vs 1.1 +/- 0.03 days; P =.001). CONCLUSION: The organization of a vascular access program in a practical and cost-effective way for reduced length of hospital stay is streamlined through a dedicated access coordinator, who ensures an integrated, multidisciplinary approach. The results for the Cox model is useful when discussing the anticipated results of access procedures with individual patients.

Algorithms↗

PubMed1995

Utility of intra-access pressure monitoring in detecting and correcting venous outlet stenoses prior to thrombosis.

Vascular access thrombosis is a major problem for hemodialysis patients. Over 7.75 years, we performed intra-access venous pressure monitoring at zero dialyzer blood flow (VP0), correlated VP0 with access anatomy angiographically, and examined the effect of two levels of stenosis, 50% and > 65% luminal diameter reduction (% D) as selection criteria for referral and elective angioplasty or surgical revision upon access outcomes. Summary receiver outcome curves for absolute intra-access pressure (VP0) and intra-access pressure normalized for systemic pressure (VP0/systolic BP) were constructed to evaluate sensitivity and specificity and compared to recirculation and duplex color-flow Doppler. Access outcomes included thrombosis, revision, replacement, and angioplasty rates that were normalized per 100 patient years (100 pt-yrs). During the 7.75 year long study period totaling 832 patient-access years of risk, the percentage of prosthetic bridge grafts increased from 65% to 80%. SROC showed better sensitivity for normalized (VP0/systolic BP) than absolute intra-access pressure (VP0) in grafts. Recirculation had poor predictive power in prosthetic bridge grafts compared to VP0. Predictive power of recirculation was superior to VP0 in native arteriovenous fistulae. The angioplasty rate correlated inversely with the degree of luminal reduction used as selection criterion for referral for angioplasty or surgical revision. A strong inverse relationship between thrombosis rate and the angioplasty rate (R2 = 0.99) but not between thrombosis rate and the number of angiograms performed (R2 = 0.39) was noted. A consistent, yet evolving, intensive graft maintenance protocol produced a 70% decrease in the thrombosis rate, a 79% decrease in the access replacement rate, and an increase in the average age of patent usable vascular accesses from 1.97 to 2.98 years that was associated with a 13-fold increase in the angioplasty rate. We conclude that vascular access monitoring with VP0/systolic BP provides excellent selection criteria for angiographic referral. Intervention for stenotic lesions > 50% D using angioplasty or surgical revision markedly reduces thrombosis and access replacement rates.

Angiography↗

PubMed2001

Assessment of a policy to reduce placement of prosthetic hemodialysis access.

BACKGROUND: The aim of this study was to evaluate the determinants of access patency and revision, including the effects of reducing the placement of prosthetic hemodialysis access. METHODS: A retrospective cohort study of all hemodialysis accesses placed at the Veteran's Administration Puget Sound Health Care System between 1992 and 1999 was conducted. A policy was instituted in 1996 that maximized the use of autogenous hemodialysis access. The impacts of the policy change, demographics, and comorbid factors on access type and patency, were examined. Primary and secondary patency rates were examined using the Kaplan--Meier method, and factors associated with failure and revision were examined using Cox proportional hazard models and Poisson regression. RESULTS: During the study, 104 accesses (61 prosthetic grafts and 43 autogenous fistulas) were placed prior to 1996, and 118 (31 prosthetic grafts and 87 autogenous fistulas) were placed after 1996. There was a significant increase in autogenous fistulas placed after 1996 (87 out of 118) compared with before 1996 (43 out of 104, P < 0.001). At one year, autogenous fistulas demonstrated superior primary patency (56 vs. 36%, P = 0.001) and secondary patency (72 vs. 58%, P = 0.003) compared with prosthetic grafts. After adjustment for age, race, side of access placement, and history of prior access placement, patients with a prosthetic graft were estimated to experience a 78% increase in the risk of primary access failure when compared with similar patients having an autogenous access [adjusted relative risk (aRR) = 1.78, 95% CI 1.21--2.62, P = 0.003)]. Similarly, the adjusted relative risk of secondary access failure for comparing prosthetic grafts with autogenous fistulas was estimated to be 2.21 (95% CI 1.38--3.54, P = 0.001). The adjusted risk of access revision was 2.89-fold higher for prosthetic grafts than for autogenous fistulas (95% CI 1.88--4.44, P < 0.001). CONCLUSIONS: Autogenous conduits demonstrated superior performance when compared with prosthetic grafts in terms of primary and secondary patency and number of revisions. A policy emphasizing the preferential placement of autogenous fistulas over prosthetic grafts may result in improved patency and a reduction in the number of procedures required to maintain dialysis access patency.

Adult↗

PubMed2002

Vascular access use in Europe and the United States: results from the DOPPS.

BACKGROUND: A direct broad-based comparison of vascular access use and survival in Europe (EUR) and the United States (US) has not been performed previously. Case series reports suggest that vascular access practices differ substantially in the US and EUR. We report on a representative study (DOPPS) which has used the same data collection protocol for> 6400 hemodialysis (HD) patients to compare vascular access use at 145 US dialysis units and 101 units in five EUR countries (France, Germany, Italy, Spain, and the United Kingdom). METHODS: Logistic analysis evaluated factors associated with native arteriovenous fistula (AVF) versus graft use or permanent access versus catheter use for prevalent and incident HD patients. Times to failure for AVF and graft were analyzed using Cox proportional hazards regression. RESULTS: AVF was used by 80% of EUR and 24% of US prevalent patients, and was significantly associated with younger age, male gender, lower body mass index, non-diabetic status, lack of peripheral vascular disease, and no angina. After adjusting for these factors, AVF versus graft use was still much higher in EUR than US (AOR=21, P < 0.0001). AVF use within facilities varied from 0 to 87% (median 21%) in the US, and 39 to 100% (median 83%) in EUR. For patients who were new to HD, access use was: 66% AVF in EUR versus 15% in US (AOR=39, P < 0.0001), 31% catheters in EUR vs. 60% in US, and 2% grafts in EUR vs. 24% in US. In addition, 25% of EUR and 46% of US incident patients did not have a permanent access placed prior to starting HD. In EUR, 84% of new HD patients had seen a nephrologist for> 30 days prior to ESRD compared with 74% in the US (P < 0.0001); pre-ESRD care was associated with increased odds of AVF versus graft use (AOR=1.9, P=0.01). New HD patients had a 1.8-fold greater odds (P=0.002) of starting HD with a permanent access if a facility's typical time from referral to access placement was < or =2 weeks. AVF use when compared to grafts was substantially lower (AOR=0.61, P=0.04) when surgery trainees assisted or performed access placements. When used as a patient's first access, AVF survival was superior to grafts regarding time to first failure (RR=0.53, P=0.0002), and AVF survival was longer in EUR compared with the US (RR=0.49, P=0.0005). AVF and grafts each displayed better survival if used when initiating HD compared with being used after patients began dialysis with a catheter. CONCLUSION: Large differences in vascular access use exist between EUR and the US, even after adjustment for patient characteristics. The results strongly suggest that a facility's preferences and approaches to vascular access practice are major determinants of vascular access use.

Adult↗

PubMed1998

Accuracy and precision of access recirculation measurements by the hemodynamic recirculation monitor.

The hemodynamic monitor (HDM) is a device that uses magnetic principles to accurately measure access recirculation during hemodialysis. The measurement is based on differential conductivity between arterial and venous blood flow rates in the dialysis blood tubing sets. One milliliter of hypertonic saline is injected into the venous line of the blood tubing set as a conductivity "tracer." As the tracer enters the patient, the presence of access recirculation causes a percentage of the hypertonic saline to recirculate into the arterial line and is detected and quantified by the HDM; the percentage of access recirculation is calculated in under 1 minute. Clinical studies were performed in two centers on 106 patients with various forms of blood access (eg, arteriovenous fistulae, Gore-tex grafts [WL Gore and Associates, Flagstaff, AZ], Permcaths [Quinton Instrument Co, Bothell, WA], subclavian catheters). Access recirculation was detected under routine dialysis conditions in only 13 patients. In the remaining cases, attempts at inducing access recirculation were made by reversing the arterial and venous lines and/or increasing the blood pump to its maximum sustainable rate for a given patient. A 15-minute protocol was then instituted. Three blood samples (arterial, venous, and "peripheral" [stop-flow technique]) were first obtained to determine urea measurements and for subsequent calculation of access recirculation; immediately afterward, an HDM recirculation measurement was recorded to allow correlation of urea and HDM access recirculation results (accuracy). Two further HDM access recirculation measurements were made to analyze the precision or repeatability of the HDM test. This protocol was attempted up to three times in each patient on different dialysis days. Two hundred fifty-nine studies were made, and a strong linear correlation was obtained between urea and HDM results (r = 0.94, slope 0.95) over a range of access recirculation (5% to 60%) demonstrating accuracy. Repeated HDM access recirculation results showed a characteristic SD of 1.8% over the whole range of values, demonstrating a precision superior to the 6% expected using the urea method. When zero access recirculation was indicated by the HDM, "ground truth" tests were performed by injecting 1 mL of hypertonic saline (HS) into one injection port of the blood tubing set then 0.1 mL of HS into the other to simulate 10% access recirculation; the mean results were 9.96%+/-1.59% (+/-SD; n = 93), confirming the accuracy of the method.

Arteriovenous Shunt, Surgical↗

PubMed1998

Accuracy of dilution techniques for access flow measurement during hemodialysis.

Access flow is now widely measured by creating artificial recirculation with the dialysis lines reversed and using dilution methods that sense either ultrasound velocity, electrical impedance, optical, or thermal changes. This study identifies and quantifies factors that influence the accuracy of access flow measurements and recommends ways to reduce these errors. Two major sources of access flow measurement error are identified, arising firstly from the second pass of the indicator by recirculation through the cardiopulmonary system (cardiopulmonary recirculation, CPR), and secondly from changes in venous line blood flow (Qb) and vascular access flow induced by the pressure of venous bolus injections. These errors are considered from theory, by direct measurement of access flow in a sheep model, and by analysis of clinical data. Two extremes for the venous introduction of indicator can be considered in access flow measurements, a slow infusion, which perturbs neither the venous line flow nor access flow but increases the error attributable to the second pass of the indicator by recirculation through cardiopulmonary system, or rapid injection, which eases separation of the second pass of the indicator signal but generates changes in the venous flow and access flow. If CPR is not eliminated, the area added to that of the first pass of indicator ranges up to 40%. Good time resolution could permit the separation of the areas generated by the first and second passage of the indicator. In sheep experiments, injections of 5 or 10 mL into a venous port close to the vascular access caused Qb to change by 20% to 40%. Both the animal experiments and analysis of raw data collected during routine clinical dialysis showed that moving the injection site sufficiently far from the patient, before or into the venous bubble trap, reduced the increase in Qb to only approximately 5% during the critical time when the concentration curve is changing for most tubing brands (Baxter, Belco, Gambro, Hospal, Medisystem, and National Medical Care). Because of the smaller volume of the venous bubble chamber in Cobe tubing (Cobe, Centrysystem 3), this brand showed approximately a 20% increase in Qb. Moving the site of bolus injections to before the bubble trap in the sheep experiments also eliminated the influence of changes in access flow. An additional error in access flow measurement of 20% or more arises from the use of flow reading taken from pump setting rather than a measured flow. The discrepancy between the real flow and pump setting is attributable to needle size, vascular access conditions, or pump calibration. The results show that problems can be minimized by using a dual sensor system that retains the precise timing necessary for separation of access recirculation from CPR; by accurate measurement of dialyzer blood flow; by moving the site of injection to before the venous bubble trap, sufficiently far from the patient, and correcting for any remaining deviations in flow in the venous line concurrent with the dilution curve.

Animals↗

PubMed2006

Effect of change in vascular access on patient mortality in hemodialysis patients.

BACKGROUND: Hemodialysis patients using a catheter have a greater mortality risk than those using an arteriovenous (AV) access (fistula or graft). However, catheter-dependent patients also differ from those with an AV access in several clinical features, and these differences may themselves contribute to their excess mortality. METHODS: The current study evaluates whether a change in vascular access affects risk for mortality in patients enrolled in the Hemodialysis Study. Time-dependent Cox regression was used to relate mortality risk to current type of access and change in access type during the preceding 1 year. RESULTS: Compared with patients who dialyzed using an AV access at both the beginning and end of the preceding 1-year interval, relative risks for mortality were 3.43 (95% confidence interval [CI], 2.42 to 4.86) in patients who dialyzed with a catheter at both times; 2.38 (95% CI, 1.76 to 3.23) in patients switching from an AV access to a catheter, and 1.37 (95% CI, 0.81 to 2.32) in patients switching from a catheter to an AV access. Change from AV access to a catheter was associated with an antecedent decrease in serum albumin level (odds ratio, 1.25; 95% CI, 1.09 to 1.45 per 0.5 g/dL; P = 0.002), weight loss (odds ratio, 1.14; 95% CI, 1.06 to 1.22 per 2 kg; P < 0.001), and decreases in equilibrated normalized protein catabolic rate (odds ratio, 2.22; 95% CI, 1.41 to 3.57 per 0.25 g/kg/d; P < 0.001) and non-access-related hospitalization (odds ratio, 1.19; 95% CI, 1.06 to 1.32 per 1 additional hospitalization over 4 months; P = 0.002). Change from a catheter to AV access was predicted by only the antecedent non-access-related hospitalization rate (odds ratio, 0.93; 95% CI, 0.87 to 0.97 per 1 additional hospitalization over 4 months; P < 0.001). CONCLUSION: Change from a catheter to AV access is associated with a substantial decrease in mortality risk.

Arteriovenous Shunt, Surgical↗

PubMed2003

[Dialock--an alternative to Permcath and access graft].

PURPOSE: An adequate vascular access is the precondition for a well-functioning hemodialysis. Due to the increasing age and the rising co-morbidity of hemodialysis patients the number of those with grafts or central venous catheters (CVC) is steadily growing. The Dialock vascular access system provides a subcutaneously implantable device for hemodialysis that combines the advantages of central venous access with percutaneous puncture. PATIENTS AND METHODS: Over a period of 30 months 26 Dialock vascular access systems were implanted at our department. 17 patients were male, 9 patients female. In 11 patients the implantation of this system was indicated for internal medicine reasons. In 15 long-term hemodialysis patients implantation was carried out as ultimate solution because of persisting vascular access problems. In a comparable control group of 22 hemodialysis patients 47 vascular accesses were registered within the same period. In parallel, another 110 patients with grafts implanted at our department at that time but not put to hemodialysis at our clinic were analysed. RESULTS: In a comparable number of access days the graft and the central venous catheter showed a considerably higher infection rate (Exit site + blood stream infection) per 1,000 hemodialysis access days than the vascular access device. The rate of malfunctions with or without subsequent lysis was higher using the CVC than when applying Dialock or graft. Angiographies with percutaneous transluminal angioplasty (PTA), or thrombectomies, respectively were significantly more often required with the graft than changes of catheter when using the vascular access system. More than half of the 110 patients observed at the same time, who had a graft implanted at our department without subsequent hemodialysis at our clinic had to undergo another surgical or radiologic intervention. CONCLUSION: The Dialock access system represents in our experience a safe and with careful application less complicated vascular access device for the complex hemodialysis patient. With comparatively low infection and complication rates the Dialock vascular access system serves as a good alternative to the permanent CVC (Permcath) as well as to the graft.

Adult↗

PubMed1999

Totally implantable venous access ports systems for patients receiving chemotherapy for solid tissue malignancies: A randomized controlled clinical trial examining the safety, efficacy, costs, and impact on quality of life.

PURPOSE: To examine the safety, efficacy, costs, and impact on quality of life of venous access ports implanted at the outset of a course of intravenous cancer chemotherapy. PATIENTS AND METHODS: Adults beginning a course of intravenous chemotherapy at two university-affiliated hospitals were randomly allocated to have venous access using a surgically implanted venous access port (Port-a-Cath; Pharmacia, Canada Inc, Montreal, Québec, Canada) or using standard peripheral venous access. All accesses were documented by number, route, purpose, and procedure duration. Outcome measurements included port complications, access strategy failure, access-related anxiety and pain, quality of life (Functional Living Index-Cancer [FLI-C]), and costs. RESULTS: Port complication rates were low (0.23/1,000 days). Failure occurred in two (3.4%) of 59 port subjects and 16 (26.7%) of 60 controls (P =. 0004) at a median period of 26 days after randomization (95% confidence interval, 8 to 92). Peripheral accesses in port subjects took less time, had less access-related anxiety and pain, and were less costly to perform than in controls. Allocation had no effect on FLI-C scores. Peripheral access failure correlated with allocation to the control group (P =.007), higher pain scores with intravenous (IV) starts (P =.003), and anxiety with IV starts (P =.01). Venous accessing overall in port patients was four times more costly than that in controls ($2,178/patient v $530/patient, respectively). CONCLUSION: Ports were safe and effective but had no detectable impact on functional quality of life, despite less access-related anxiety, pain, and discomfort. Because only approximately one quarter of control patients ultimately required central venous access, economic considerations suggest that port-use policies should be based upon defined criteria of need.

Adult↗

PubMed2001

IgM anticardiolipin antibodies are associated with stenosis of vascular access in hemodialysis patients but do not predict thrombosis.

AIM: The prevalence of anticardiolipin antibodies (ACA) is elevated amongst hemodialysis patients as compared with the general population. Previous studies have disagreed as to whether the presence of ACA represents a risk factor for access thrombosis. Other risk factors for access thrombosis (decreased blood flow, elevated venous pressure) have also been described. MATERIALS AND METHODS: We performed a combination retrospective and prospective cohort study of a single outpatient dialysis unit to assess the association between these potential risk factors and access thrombosis. ACA, access blood flow, presence of stenosis, and venous pressures were measured in 100 patients. Information on episodes of access thrombosis was gathered for 12 months prior to and 12 months after ACA measurement. RESULTS: ACA were present in 19% of patients with equal numbers of IgG- and IgM-ACA. The presence of IgM-ACA was significantly associated with the use of aspirin and the presence of stenosis by Doppler at the time of ACA testing (p < 0.05). A logistic regression model was used to estimate the association between clinical factors and access thrombosis. In this multivariate analysis, the presence of access stenosis and a history of access thrombosis were both significantly associated with the development of access thrombosis. Adjusted for these variables, neither IgG- nor IgM-ACA was significantly associated with access thrombosis. The presence of an ACA was not associated with episodes of access thrombosis in either the prospective or retrospective analyses. CONCLUSION: Further investigation is required to determine if the association between aspirin use and IgM-ACA, or of IgM-ACA and access stenosis, has implications for underlying pathogenetic mechanisms of access stenosis.

Adult↗

PubMed2005

[Monitoring protocol of native vascular accesses for haemodialysis].

Vascular access failure is an important cause of morbidity and mortality for patients on haemodialysis. We have prospectively studied, with a 5 years follow up, a monitoring protocol of native vascular accesses, using the available methods in every haemodialysis unit. All the native vascular accesses, created from 1- 1998 to XII-2001, with a posterior follow up until XII-2002, were monitored. Monitoring was based on physical examination, dificulty for blood flow greater than 300 ml/min, and in a monthly basis: dynamic venous pressure, urea recirculation and urea kinetic model. Abnormalities suggestive of fistulogram were a priori defined. During the recruitment period, a total of 164 accesses were created in 144 patients. Of these only 3 were grafts, 28 native vascular accesses were never functioning (primary failure rate 17. 1%), and 127 native accesses created in 113 patients (age 63.3 +/- 12.4 years; 18 % diabetics), were monitored (83% cephalic vein). Monitoring findings indicated realization of fistulogram in 35% and percutaneus angioplasty in 25% of the accesses. In order to maintain patency, the surgical intervention rate was 0.03 procedures/patient/year, the radiological 0.10 and the total 0.13. During the 5 years of the study occurred 41 thrombosis episodes in 40 accesses (0.07 thrombosis/patient/year), with percutaneus repermeabilization in 30%. Primary (unassisted) survival was 30.3 months (Confidence Interval 95% 25.6, 35.0) and secondary (assisted) survival 42.8 months (Confidence Interval 95%: 38.7, 46.9). Logistic regression analysis showed that presence of a central catheter at the time of creating the vascular access posses a greater risk for thrombosis (Relative Risk 5.6 if in subclavian vein), whereas age, diabetes, time to canulation, number of previous accesses and anatomic type do not increase that risk. In conclusion, in an old haemodialysis population, with an important diabetes prevalence, it is possible to create functioning native vascular accesses in most of them. The monitoring protocol allowed the detection and posterior correction of stenosis in a great number of accesses. The main risk of thrombosis is the presence of a central catheter at the time of creating a vascular access.

Catheters, Indwelling↗

PubMedDate not supplied

[Anatomic rationale for a transmaxillary access to the cavernous sinus].

UNLABELLED: W. Couldwell et al. were the first to propose a transmaxillary access to the cavernous sinus in 1997. The authors showed that this approach was low-invasive and cosmetic and it ensured visualization of different nervous formations of the cavernous sinus and the intracavernous segment of the internal carotid artery. This study was undertaken to study microsurgical anatomy, to simulate a transmaxillary access, to demonstrate its expediency, and to assess the use of endoscopic techniques when this access was applied. The study was conducted in 3 steps: 1) a craniometric study on 33 skulls and 25 craniograms to examine the craniological and geometric parameters of the anatomy of the osseous structures included into the transmaxillary access; 2) simulation of the access on the osseous structures of the skull (2 sides); by including anterior and posterior maxillotomy and bone drilling-out around the round foramen; 3) microsurgical preparation--dissection was performed on 3 head samples (5 sides) at the Laboratory of Microneurosurgical Anatomy, Acad. N. N. Burdenko Research Institute of Neurosurgery, Russian Academy of Medical Sciences. Endoscopy was tested when the transmaxillary access was applied. The results were as follows: 1. The depth of the access failed to correlate with the shape of the skull. The operative observation angle averaged 18-23 degrees. 2. Simulation of the transmaxillary access on the dried skull made it possible to visualize the medial portion of the infratemporal fossa, by enlarging the pterygpid-maxillary fissure. The bone drilling-out boundaries for the skull base were defined. 3. Microsurgical dissection after removal of the posterior maxillary sinus wall and opening the pterygopalatine fossa. The topography of the maxillary artery and nerve was studied. After drilling out the bone of the skull base, the lower wall of the cavernous sinus was crescent. The cavernous sinus was opened as far as possible both above the maxillary nerve and between the second and third branches of the trigeminal nerve. CONCLUSIONS: 1. The access is deep and narrow, yet low-traumatic. 2. It may be the access of choice in removing a small pathological focus in the pterygopalatine fossa, round foramen or lower portions of the cavernous fossa. 3. The access may be used to approach the medial portion of the infratemporal fossa. 4. The described stepwise microsurgical anatomy and internal guiding lines in the retromaxilllary space permit one to perform surgical operations with confidence. 5. With this access, there is no guidance over the great vessel (internal carotid artery). 6. The access passes through the vestibule of the mouth; in this connection its application is undesirable at surgery for intradural abnormalities.

Cavernous Sinus↗

PubMed1984

Patterns of ethanol consumption as a function of the schedule of ethanol access.

The present experiment demonstrated that patterns of ethanol consumption can be controlled by altering the schedule of ethanol availability. Thirty-two male albino rats, maintained at 80% of their ad libitum weight, were first exposed to 10 base-line sessions in which access to either 8 or 32% ethanol was unrestricted. Each subject was then exposed to one of four restricted access schedules for 30 sessions. During each 23-hr session, the ethanol access period was held constant at 20 min while the time between ethanol access periods was either 70, 160, 340 or 700 min. After restricted access, all subjects were returned to unrestricted access for 10 sessions. Water was continually available throughout the experiment. When ethanol access periods occurred every 70 or 160 min, animals at both concentrations consumed more ethanol (grams per kilogram) than during the initial period of unrestricted access. When the time between ethanol access periods was 340 or 700 min, animals consumed an equal amount or half as much, respectively, as during unrestricted access. Analysis of responding revealed that the mean amount of ethanol consumed per bout was greater during restricted than during unrestricted access. The longer the time between access periods the greater the amount consumed per bout. Upon return to unrestricted access, total daily consumption increased, but the amount consumed per bout decreased to base-line levels.

Alcohol Drinking↗

PubMed2005

The index of multiple deprivation 2000 access domain: a useful indicator for public health?

The access domain of the UK index of multiple deprivation (IMD) 2000 was designed to identify populations in small areas with poor geographical access to certain local key services. The measure is a composite of straight line distances to post offices, large food shops, primary schools and general practice surgeries for population sub-groups. Using the region of East Anglia as a case study area, this research evaluated the utility of the IMD2000 as an indicator of access to primary care. IMD2000 access scores for electoral wards were compared with a range of more detailed indicators of travel times and bus availability for visiting a general practitioner generated in a geographical information system (GIS). A range of easy-to-calculate surrogate variables was developed and tested as possible candidates to improve the explanatory power of the IMD2000 access score. The access domain was negatively correlated with the other five deprivation domains that comprise the overall index, suggesting that access should not be combined with the other measures of deprivation into a composite single score. The access domain was also found to predict access to primary care only with moderate accuracy. Two additional indicators of accessibility calculated in a GIS (road kilometres per thousand population and the presence of a major road in each ward) were found to add slightly to the power of the index. The predictive power of the index was best in urban areas, although it is in rural areas that access to primary care is a more important public health issue. The IMD2000 should be therefore used with caution as a measure of health service accessibility in rural areas.

Catchment Area, Health↗