Reducing catheter infections through use of the CD-1000: a retrospective review of a unique catheter specific composite dressing.

PURPOSE: Catheter-related blood stream infections pose a significant risk for patients living with vascular catheters. The cost to manage these infections is substantial. Although the etiology of these infections is multifactorial, tap water has been implicated as a significant causative factor. This retrospective review evaluates the effectiveness of a surgical dressing, the CD-1000, at protecting catheters and exit site wounds from fluid and debris when patients engage in high risk activities like showering. METHODS: All patients who received the CD-1000 from a single national medical supplier from September 2006 through to March 2007 were contacted to participate in this retrospective review; 209 patients, representing 34 states and 175 unique physicians, participated in this study. Effectiveness of the dressing along with prior and current history of catheter events was queried. RESULTS: The CD-1000 was 95% effective at keeping the catheter and exit site dry while patients engaged in high risk activities like showering. Prior to using the CD-1000, the 209 patients reported a historical catheter infection rate of 1.83 per 1000 catheter days. While using the CD-1000 the 209 patients reported a catheter infection rate of 0.47 per 1000 catheter days. CONCLUSION: The CD-1000 catheter specific composite dressing adequately protects vascular catheters and exit sites when patients engage in high risk activities like showering. In this geographically diverse retrospective review, use of the CD-1000 was associated with a 75% reduction in catheter associated infections.

Antibiotic lock technique for prevention of cuffed tunnel catheter associated bacteremia.

BACKGROUND: Central venous cuffed tunnel catheters are commonly used for short term or long term hemodialysis access. However, catheter-associated bacteremia is a common complication. It has been suggested that the addition of antibiotics to the catheter during the interdialytic interval results in a decrease in bacterial colonization and thereby a decrease in catheter associated infections. To test this hypothesis, a prospective, randomized study was performed comparing a gentamicin citrate mixture to standard heparin as the catheter lock. The effect of covering the catheter hub in a sterile bag on the infection rate was additionally tested. METHODS: From January 1999 to April 2000, all patients who underwent tunnel catheter placement or change (55 catheters) in the Nephrology Interventional Laboratory at Louisiana State University Health Sciences Center in Shreveport, were prospectively randomized as follows: group 1 (n=14): Antibiotic lock with tricitrasol (46.7%), gentamicin (40 mg/ml) and saline in a ratio of 1:5:5 and catheter hub covered with a sterile plastic bag after cleaning with a 10% povidone iodine solution; group 2 (n=22): Heparin lock and sterile plastic bag over catheter hub after cleaning with povidone iodine; and group 3 (n=19): Heparin lock alone. The primary end points of the study were catheter-associated bacteremia and thrombosis. Catheter loss due to access maturation, transplant or transfer were censored. RESULTS: There were a total of 4,805 at risk patient-days. The total number of catheter associated bacteremias were one in group 1, four in group 2 and four in group 3. The number of catheter associated bacteremias per 1000 patient-days in each group was 0.62, 3.05, and 2.11 respectively. The sixty day percent survival of catheters in each group was 74 +/- 12, 55 +/- 12 and 59 +/- 11 respectively. CONCLUSIONS: 1) Tricitrasol and gentamicin as an antibiotic lock reduced the incidence of catheter associated bacteremia; 2) Covering the catheter hub with a sterile bag did not provide an additional advantage; 3) The antibiotic lock improved overall survival of catheters.

Chronic catheter placement.

Since the 1997 publication of the Disease Outcomes Quality Initiative (DOQI) vascular access guidelines for cuffed, tunneled catheter placement, additional evidence supporting these recommendations has been published, including additional documentation supporting the right internal jugular vein as the preferred site for insertion. Placing the catheter tip in the right atrium rather than in the superior vena cava will provide adequate blood flow to support effective hemodialysis. The right atrial positioning of the catheter tip will also accommodate catheter tip retraction and decrease the likelihood of malfunction. Overwhelming evidence now supports the use of ultrasound guidance to assist cannulation of the internal jugular vein. This evidence is based on several studies documenting anatomical variations of the internal jugular vein. Ultrasound guidance has significantly decreased the incidence of serious complications of jugular vein cannulation. Finally, a specific technique of catheter placement with variations for catheter types is described.

Roux-en-Y venting jejunostomy in pancreatic transplantation: a novel approach to monitor rejection and prevent anastomotic leak.

INTRODUCTION: Pancreatic transplantation (PTx) with portal venous delivery of insulin and enteric drainage of the exocrine secretion is more physiologic than bladder-systemic (BS) drainage. With portal-enteric (PE) PTx, the diagnosis of acute rejection (AR) requires a percutaneous biopsy. The roux-en-y (RNY) venting jejunostomy in patients with PEPTx offers a novel approach to monitor rejection and prevent anastomatic leaks. METHODS: From January 1996 to December 1998, we performed 17 simultaneous kidney/pancreas transplants (SKPTx). The initial 4 patients underwent BS drainage and the subsequent 13 patients underwent RNY venting jejunostomy with PE drainage. All patients were treated with quadruple therapy. There were 9 males, 14 patients were Caucasian with a mean age of 32 yr (range 30-54 yr), and a mean pre-transplantation duration of diabetes of 25 yr. Six patients underwent endoscopic donor duodenal biopsy through the jejunostomy to rule out clinically suspected AR. Gastrograffin was inserted into the jejunostomy to examine the integrity of anastamosis when indicated. In 9 out of 13 patients, the venting jejunostomy was taken down 9-12 months post-transplantation after allograft function was stable. RESULTS: Actual patient, kidney, and pancreas graft survival rates were 100, 100 and 94%, respectively, after a mean follow-up of 16 months. Renal allografts functioned immediately in 89% of patients. The mean length of hospital stay was 19 d. Four (23%) patients (2 with BS drainage and 2 with PE drainage) suffered an AR episode in the first month, and 4 (23%) patients had five AR from 3-36 months post-transplantation. Other complications were post-operative bleeding in 3 patients, wound infection in 2 patients and a proximal duodenal stump leak in 1 patient. In patients with clinical rejection, endoscopy through the venting jejunostomy showed inflamed, friable doudenal mucosa and doudenal biopsy findings were compatible with AR. CONCLUSION: These preliminary results suggest that RNY venting jejunostomy with PE drainage can be used safely to diagnose and monitor pancreas AR and to diagnose and prevent anastamotic leaks. This technique will be even more useful to visualize transplanted duodenal mucosa, collect pancreatic secretions (amylase) for analysis and perform endoscopic retrograde cholangiopancreatography if needed to obtain pancreatic biopsies.

Hybrid dialysis: recirculation peritoneal dialysis revisited.

In a crossover trial, eight patients were studied during one treatment each of automated peritoneal dialysis (APD) and hybrid dialysis (HyD). During HyD, a fixed quantity of peritoneal dialysis fluid (PDF) was continuously removed at a flow rate of 141.3 +/- 23. 7 mL/min, dialyzed against the secondary dialysate (250 +/- 53.5 mL/min) generated by the hemodialysis delivery system with single-needle dialysis capability, and the regenerated PDF (PDF(HyD)) was reinfused into the peritoneal cavity. Despite using a smaller volume (6,195 +/- 737 versus 13,321 +/- 1,201 mL; P < 0. 0001) of PDF(HyD) with a lower glucose concentration (729 +/- 562 versus 1,659 +/- 373 mg/dL; P < 0.0001) and osmolality (331 +/- 79 versus 387 +/- 184 mOsm/kg; P < 0.001) during HyD compared with APD (PDF(APD)), weight loss was similar with both treatments (1.4 +/- 1. 0 versus 1.6 +/- 1.2 kg). Lactate levels were lower (3.2 +/- 2.5 versus 11.4 +/- 5.4 mEq/L), but pH (7.5 +/- 1.3 versus 5.6 +/- 0.9; P < 0.001) and bicarbonate concentration (22.6 +/- 8.0 versus 11.9 +/- 7.9 mEq/L; P < 0.0001) were greater in PDF(HyD) than PDF(APD). Although the mean dialysate calcium level was lower (6.0 +/- 0.5 versus 6.9 +/- 1.1 mg/dL; P < 0.001) in PDF(HyD), it was more stable throughout the dialysis compared with PDF(APD). A steeper concentration gradient between the blood and dialysate resulted in greater clearance of urea (26.5 +/- 9.1 versus 11.0 +/- 4.7 mL/min; P = 0.04), creatinine (24.1 +/- 11.4 versus 12.0 +/- 7.9 mL/min; P = 0.03), phosphate (19.2 +/- 4.3 versus 9.8 +/- 7.2 mL/min; P = 0.01), and uric acid (15.6 +/- 6.9 versus 9.1 +/- 2.7 mL/min; P = 0.04) and a greater percentage of reduction in values for blood urea nitrogen (20.7% +/- 7.7% versus 11.6% +/- 5.5%; P = 0.02), serum creatinine (16.1% +/- 5.3% versus 6.6% +/- 3.0%; P < 0.001), phosphate (22.7% +/- 8.9% versus 9.8% +/- 4.5%; P = 0.004), and uric acid (15.8% +/- 2.9% versus 6.3% +/- 3.4%; P < 0.001) during HyD than APD. To conclude, HyD is a novel dialytic technique that uses biocompatible bicarbonate-based dialysate to achieve excellent clearance of uremic toxins and ultrafiltration with minimal glucose load.

Accuracy of decrease in blood flow in predicting hemodialysis graft thrombosis.

We recently showed that a single low graft blood-flow measurement (Qa) does not accurately predict graft thrombosis. In this study, we prospectively determined whether percentage of decrease in Qa (DeltaQa) or adjustment of Qa for mean arterial pressure (Qa/MAP; Delta(Qa/MAP)) provides greater predictive accuracy than a single Qa. We monitored 83 grafts from 80 patients for thrombosis over periods up to 12 months. Qa (by ultrasound dilution) and MAP were measured monthly during the study. Receiver operating characteristic curves were used to determine whether Qa, DeltaQa, Qa/MAP, or Delta(Qa/MAP) provided the combination of high sensitivity (>80%) and low false-positive rate (FPR; <20%) needed for clinical use. This level of predictive accuracy requires an area under the curve (AUC) of approximately 0.90. We analyzed the four predictors by a number of criteria and found that all AUCs were less than 0.90 and adjustment for MAP reduced the AUC. In predicting thrombosis within 1 month, for example, AUCs for Qa and net DeltaQa (over 3 months) were 0.84 and 0.82, respectively, whereas AUCs for Qa/MAP and net Delta(Qa/MAP) were 0.78 and 0.75, respectively. At a sensitivity of 80%, FPRs for all predictors were at least 30%. Thus, a high sensitivity always required a high FPR. These results show that DeltaQa and adjustment for MAP are not more accurate than a single low Qa in predicting thrombosis. None of these predictors provide enough predictive accuracy to be the sole criterion for clinical decision making. A successful monitoring and intervention program will likely require the inclusion of other predictors that, together with Qa, may provide the needed accuracy.

Heme oxygenase modulates selectin expression in different regional vascular beds.

Heme oxygenase (HO) catalyzes the degradation of heme to biliverdin, iron, and CO. The inducible isoform (HO-1) has been implicated as a modulator of the inflammatory response. HO-1 activity can be induced by hemin and inhibited with zinc protoporphyrin IX (ZnPP). Using these reagents, we assessed the possibility that HO-1 modulates the inflammatory response by altering the expression of endothelial cell adhesion molecules. Endotoxin (lipopolysaccharide, LPS)-induced expression of P- and E-selectin expression was quantified in different vascular beds of the rat using the dual radiolabeled monoclonal antibody technique. Pretreatment with hemin attenuated, whereas ZnPP treatment exacerbated, the increased selectin expression normally elicited by LPS. Biliverdin, at an equimolar dosage, was as effective as hemin in attenuating LPS-induced selectin expression in the lung, kidneys, liver, and intestines. These findings indicate that the anti-inflammatory properties of HO-1 may be related to an inhibitory action of P- and E-selectin expression in the vasculature. Biliverdin (or its metabolite, bilirubin), rather than CO, may account for this action of HO-1 on endothelial cell adhesion molecule expression.

In search of ideal hemodialysis: is prolonged frequent dialysis the answer?

Advances in technology have made it possible to deliver a high Kt/V in a shorter time. The realization that duration of dialysis may be an important predictor of survival independent of dialysis dose has resulted in the popularity of prolonged slow dialysis (PHD). The longer duration and increased frequency of dialysis achieve excellent small- and middle-molecular weight solute clearance and also attenuate the peak concentration of uremic toxins. The slow dialysis process enables the equilibration of tissue and vascular compartments, resulting in better clearance and decreased postdialysis rebound increase in solutes. Gentle, persistent ultrafiltration allows the control of hypertension with minimal antihypertensive use. The intense and more frequent dialysis improves appetite and permits liberalization of diet. This greater dietary protein intake results in a progressive increase in serum albumin level and dry weight. Nocturnal hemodialysis achieves control of hyperphosphatemia without phosphate binders and a significant reduction in serum beta(2)-microglobulin levels. Normalization of extracellular volume, better clearance of uremic toxins, and improved nutrition result in a significant improvement in survival. The flexible time schedule with home hemodialysis and improvement of sleep and neurocognitive function allow better rehabilitation. The available evidence indicates PHD may be closer to the concept of an ideal dialysis, but there is lingering uncertainty about the consequence of prolonged immune stimulation, catabolism, and loss of essential solutes with these therapies.

Does blood flow accurately predict thrombosis or failure of hemodialysis synthetic grafts? A meta-analysis.

A number of studies have reported that a single low blood flow (Qa) measurement in synthetic hemodialysis grafts predicts thrombosis or failure. In a meta-analysis of these studies, we computed receiver operating characteristic (ROC) curves that evaluated the predictive accuracy of a Qa measurement. The ROC curves plotted sensitivity versus false-positive rate for predicting thrombosis or failure at different Qa thresholds. A perfect predictor has an area under the curve (AUC) of 1.0, whereas a predictor with no discriminative ability has an AUC of 0.5. We identified studies through a literature search and included our own unpublished data. A random-effects model was used to combine the ROC curves from different studies. Of 19 identified studies, 12 were suitable for computing binormal ROC curves (6 predicted thrombosis; 6 predicted failure). The studies measured Qa and then observed outcome during periods of 1.5 to more than 6 months. The combined AUCs from these studies indicate Qa was a relatively poor predictor, with 0.70 +/- 0. 04 (range, 0.61 to 0.84) for thrombosis and 0.76 +/- 0.07 (range, 0. 62 to 0.90) for failure. The wide range of AUCs also shows there was much heterogeneity between studies. We conclude that a single Qa measurement does not appear to have enough accuracy to be a clinically useful predictor of graft thrombosis or failure. Serial Qa measurements and identification of factors that caused heterogeneity between studies may be needed to achieve sufficient accuracy.

Are all successful renal transplants really successful?

We previously described a small group of renal transplant recipients considered to have successful allografts statistically, but who did not benefit clinically. These were patients in whom the grafts survived greater than 6 months but less than 3 years. This expanded study evaluates 179 consecutive renal transplant recipients divided into three groups. Group 1 (n = 18), group 2 (n = 41), and group 3 (n = 120) have patients with graft survival less than 6 months, between 6 months and 3 years, and greater than 3 years, respectively. Mean age, cause of renal failure, HLA match, and immunosuppressive regimen were not statistically different in any group. The number of acute rejection episodes, number of hospitalizations, and number and seriousness of complications were significantly greater in group 2 patients compared with the other groups. Patients in group 2 experienced five times the number of acute rejections (P < 0.0001), three times the number of hospitalizations (P < 0.0001), and two times the number of complications (P < 0.0001) compared with group 3 patients. In conclusion, those transplant recipients whose grafts survived longer than 6 months but less than 3 years were the most unfortunate. They experienced repeated and serious complications and spent many days in the hospital at great expense. A study with more sensitive methods of detecting presensitization might impact on graft performance in the future.

Is peritoneal dialysis a good option for black patients?

Blacks are less likely than whites to use peritoneal dialysis (PD) as the initial renal replacement therapy. The reason for the underusage of PD by blacks is unknown. In a cross-sectional multicenter trial, we studied peritoneal transport character, small-molecular-weight solute clearances, and nutritional status in 475 patients undergoing PD (168 whites, 192 blacks, and 115 Asians). The mean age of blacks undergoing PD was significantly younger than that of whites (47.6 +/- 14.7 v 58.2 +/- 16.7 years; P < 0.0001). Target Kt/V and weekly creatinine clearance (WCC) as defined by the Dialysis Outcome Quality Initiative Work Group was achieved by 62.5% of whites, 67.2% of blacks, and 54.8% of Asians (P = 0.05). Total protein (7.25 +/- 0.88 v 6.55 +/- 0.73 g/dL), albumin (3.72 +/- 0.57 v 3.55 +/- 0.53 g/dL), and lean body mass (LBM; 41.7 +/- 15.6 v 33.0 +/- 11.8 kg) were lower in whites compared with blacks (P < 0.001). Although the normalized protein catabolic rate (nPCR) was greater (0.82 +/- 0.24 v 0.90 +/- 0.32 g/kg/d; P = 0.04), total protein (6.24 +/- 0.85 g/dL) and serum albumin levels (3.36 +/- 0.52 g/dL) and LBM (30.1 +/- 8.0 kg) were significantly lower in Asians than blacks (P < 0.0001). The favorable anabolic response in blacks may partially be explained by a higher calorie intake in this group of patients (29.6 +/- 10.7 Cal/kg/d) compared with whites (22.4 +/- 6.8 Cal/kg/d) and Asians (23.9 +/- 9.8 Cal/kg/d; P = 0.03). Multiple regression analysis identified that black race and weight were positively associated, whereas dialysate/plasma creatinine ratio (D/P(Creat)) and age had a negative effect on serum albumin level. Follow-up data indicated that the Kt/V (2.09 +/- 0.50 v 2.39 +/- 0.56; P = 0.02) and WCC (60.8 +/- 4.3 v 70.2 +/- 7.3 L/1.73 m2; P = 0.02) increased significantly from baseline only in blacks. We conclude that PD is an ideal renal replacement therapy in at least a subset of blacks with end-stage renal disease.

Peritoneoscopic versus surgical placement of peritoneal dialysis catheters: a prospective randomized study on outcome.

The most commonly used technique for insertion of peritoneal dialysis (PD) catheters is open surgical approach by minilaparotomy. Percutaneous implantation via the peritoneoscopic technique is expanding. Studies have suggested that PD catheters placed peritoneoscopically have longer survival rate than surgically placed ones. However, these studies were not randomized, where the surgical group had more patients who were obese or had prior abdominal surgery, and therefore, the selection of patients may have biased the results. We conducted a prospective randomized study in which patients underwent PD catheter placement by either the surgical or the peritoneoscopic technique. In the period from October 1992 through October 1995, 148 double-cuff, curled-end, swan-neck PD catheters were placed in 148 patients. The outcome of the 76 patients in whom the PD catheters were placed peritoneoscopically was compared with that of the 72 patients in whom the catheters were placed surgically. Early peritonitis episodes (within 2 weeks of catheter placement) occurred in 9 of 72 patients (12.5%) in the surgical group, versus 2 of 76 patients (2.6%) in the peritoneoscopy group (P = 0.02). This higher rate of infection was most likely related to a higher exit site leak in the surgical group (11.1%) as compared with the peritoneoscopy group (1.3%). Moreover, peritoneoscopically placed catheters were found to have better survival (77.5% at 12 months, 63% at 24 months, and 51.3% at 36 months) than those placed surgically (62.5% at 12 months, 41.5% at 24 months, and 36% at 36 months) with P = 0.02, 0.01, and 0.04, respectively. We conclude that peritoneoscopically placed PD catheters have a longer survival rate than surgically placed ones. Furthermore, the rate of exit site leak and early infection is lower in the peritoneoscopic method.

Accuracy of Doppler ultrasound in diagnosing anatomic stenosis of hemodialysis arteriovenous access as compared with fistulography.

A variety of techniques (physical examination, venous pump pressure, percent urea recirculation, Crit Line, Transonic Flow, and others) are helpful in detecting vascular access dysfunction with subsequent referral to fistulography for confirmation of stenosis and possible angioplasty. Although these techniques are adequate, it is not uncommon that the results in some patients may be borderline or equivocal. In these cases, Doppler ultrasound may play a role to confirm the presence or absence of significant stenosis before subjecting the patient to the more expensive and invasive fistulography. For Doppler ultrasound to play such a role, it must have a high degree of accuracy in diagnosing anatomic stenosis. In previous studies, percent stenosis by Doppler ultrasound as compared with percent stenosis by fistulography was examined only when stenosis was suspected, therefore not allowing the determination of Doppler ultrasound specificity in diagnosing negative stenosis when fistulography was negative. In this study, we evaluated 38 hemodialysis patients with Doppler ultrasound followed by fistulography, without regard to suspicion of stenosis (to access both the sensitivity and specificity of Doppler ultrasound). Nineteen patients (50%) had significant stenosis by fistulography (> or =50% narrowing). The same 19 patients had significant stenosis by Doppler ultrasound (significant stenosis at > or =40% with high-velocity flow turbulence or > or =50% without turbulent flow), whereas the remaining patients had no significant stenosis. In addition, the percent stenosis by Doppler ultrasound had a linear relationship to the percent stenosis by fistulography. In conclusion, Doppler ultrasound closely correlates to fistulography in diagnosing anatomic stenosis. In patients in whom other techniques for diagnosing access stenosis show borderline results, Doppler ultrasound may play an adjuvant role to confirm the presence or absence of significant stenosis.

Accuracy and reproducibility of urea recirculation in detecting haemodialysis access stenosis.

BACKGROUND: There is wide disagreement among studies that have evaluated the accuracy of urea recirculation (UR) in detecting vascular access stenosis. The 3-site method (UR3) has been discredited and replaced by the 2-site method (UR2), but few studies have evaluated UR2. METHODS: We compared the accuracies of UR2 and UR3 in detecting stenosis in 59 haemodialysis patients during a 12-month period. All patients were studied without regard to clinical suspicion of stenosis. Stenosis (> or = 50% luminal narrowing) was diagnosed by duplex ultrasound and confirmed by angiography. The reproducibility of UR2 was determined by computing its total standard deviation (SDTOT) from measurements during three dialysis sessions over a 15-day period. RESULTS: Stenosis was found in 32% of 124 access studies (mean luminal narrowing = 58%, range = 50%-83%). The mean UR values of stenotic accesses were only slightly higher than non-stenotic accesses for both UR2 (5.6% vs 2.9%, P < 0.01) and UR3 (13.1% vs 11.2%, P = 0.22). An increase in blood pump speed from 300 to 425 ml/min did not improve detection of stenosis by UR2. There were no UR thresholds that could adequately separate the presence of stenosis from its absence. The SDTOT of UR2 was 3.8%, indicating that a patient's UR2 measurement may vary over a range of 16% (+/- 2SDTOT = +/- 8%). CONCLUSION: Stenosis of the haemodialysis access does not predictably cause recirculation, and the reproducibility of the UR2 measurement is poor.

Preoperative vancomycin prophylaxis decreases incidence of postoperative hemodialysis vascular access infections.

The role of vancomycin in the treatment of infected arteriovenous chronic dialysis access is well established. However, the role of preoperative vancomycin administration in preventing infection in newly placed, revised, or surgically thrombectomized grafts has not been determined. We performed a prospective randomized study to examine whether vancomycin prophylaxis can decrease the incidence of postoperative graft infections. Over a 5-year period, 206 patients undergoing 408 permanent vascular access procedures were randomized into two groups. Group 1 (206 procedures) received a single intravenous dose of 750 mg of vancomycin approximately 6 to 12 hours before vascular access placement procedures, while group 2 (202 procedures) did not. Patients were evaluated for access infection within the following 30 days and before use of the access for chronic dialysis. Access infection developed in two patients (1%) in group 1 and in 12 patients (6%) in group 2 (P = 0.006). All 14 infections occurred in upper extremity polytetrafluoroethylene grafts. We conclude that the use of preoperative single-dose intravenous vancomycin prophylaxis for hemodialysis vascular graft procedures reduces the risk of postoperative access infection.

Peritoneal dialysis solutions reverse the hemodynamic effects of nitric oxide synthesis inhibitors.

Nitric oxide (NO) synthesis is inhibited by a variety of L-arginine analogs including NG-nitro-L-arginine methyl ester (L-NAME) and NG NG-dimethylarginine (ADMA). ADMA is present in elevated concentrations in renal failure and potentially could alter microcirculatory hemodynamics during peritoneal dialysis (PD). This investigation utilized the techniques of intravital microscopy to quantitate the mesenteric arteriolar hemodynamic effects of PD solutions during NO synthesis inhibition. L-NAME (100 microns) produced maximum arteriolar vasoconstriction to 74% of baseline diameter (19.9 +/- 2.2 vs. 26.9 +/- 1.4 microns, P < 0.001, N = 10) and ADMA (100 microns) to 68% (20.5 +/- 2.5 vs. 30.1 +/- 2.0 microns, P < 0.01, N = 6). L-NAME decreased red blood cell velocity to 44% of baseline velocity (3.8 +/- 0.8 vs. 8.5 +/- 1.1 mm/second, P < 0.001) and ADMA to 52% (5.1 +/- 1.1 vs. 9.8 +/- 0.9 mm/second, P < 0.01, N = 6). Despite NO synthesis inhibition, standard PD solutions reversed these hemodynamic effects with both 1.5% and 4.25% Dianeal (Baxter) rapidly reversing the vasoconstriction and restoring blood flow back to baseline values. When Dianeal and L-NAME were simultaneously superfused, no L-NAME induced vasoconstriction occurred and Dianeal maintained vasodilatory properties despite L-NAME (P < 0.01, N = 5). This investigation reaffirms that basal levels of NO are important in maintaining normal hemodynamics in the mesenteric microcirculation. Reversal of the L-NAME induced arteriolar hemodynamic effects by Dianeal suggests that the endogenous NO synthesis inhibitor ADMA has no significant effects in the regulation of the mesenteric microvascular arteriolar hemodynamics during PD. Since these PD solutions remain vasoactive despite NO synthesis inhibition, this suggests that these PD solutions possess vasoactive properties primarily through a NO independent mechanism.