Tung-Po Huang

Hemodialysis-Related Pruritus: A Double-Blind, Placebo-Controlled, Crossover Study of Capsaicin 0.025% Cream

Pruritus is a significant symptom among patients receiving hemodialysis. However, its underlying mechanisms remain obscure. Substance P, a neuropeptide, has been implicated in the mediation of pain and some itch sensations. Local application of capsaicin depletes the peripheral neurons of substance P and may block the conduction of pain or pruritus. This study aims to assess the efficacy and safety of capsaicin 0.025% cream in the treatment of hemodialysis-related pruritus and to further explore the underlying pathomechanism. Nineteen hemodialysis patients with idiopathic, moderate (n = 5) to severe (n = 14) pruritus were examined in a double-blind, placebo-controlled, crossover study and 17 of them completed the study. Topical agent of capsaicin or placebo base cream was applied to localized areas of pruritus 4 times a day. The severity of pruritus and treatment-related side effects (cutaneous burning/stinging sensations, dryness, or erythema) were evaluated weekly. The results showed (1) that 14 of 17 patients reported marked relief and 5 of these 14 patients had complete remission of pruritus during capsaicin treatment (Wilcoxon signed-ranks test, 2p < 0.001); (2) capsaicin was significantly more effective than placebo (Mann-Whitney rank sum test, 2p < 0.001) and a prolonged antipruritic effect was observed 8 weeks posttreatment; (3) no serious side effects were noted during the study and (4) there were no significant changes in serum concentrations of albumin, calcium, phosphorus, alkaline phosphatase, or intact parathyroid hormone during the treatment with either capsaicin or placebo. In summary, the present study indicates indirectly that idiopathic pruritus in some patients on maintenance hemodialysis may be transmitted by substance P from the peripheral sensory neurons to the central nervous system. Topical capsaicin with the unique pharmacological effect is demonstrated to markedly improve the pruritus of these patients.

Uremic pruritus : Roles of parathyroid hormone and substance P

BACKGROUND Most patients receiving maintenance hemodialysis have pruritus, but its underlying mechanism remains unknown. Secondary hyperparathyroidism is another common problem in these patients, but its role in uremic pruritus is controversial. Capsaicin can deplete substance P from the peripheral neurons and is known to be effective in the treatment of pain and itching. OBJECTIVE Our purpose was to evaluate the role of parathyroid hormone (PTH) and substance P in uremic pruritus and to elucidate the underlying mechanisms. METHODS The study contained two phases. In phase I, we analyzed the correlation between the intensity of itching and serum levels of intact PTH. In phase II, patients with moderate to severe pruritus were placed into two groups: one with high PTH levels and one with low levels. A double-blind, placebo-controlled study of capsaicin 0.025% cream was conducted in phase II. RESULTS Serum levels of intact PTH did not correlate with the intensity of pruritus and did not significantly change during treatment with capsaicin or placebo. Capsaicin was significantly more effective in alleviating uremic pruritus than the placebo, and no serious side effects were noted. CONCLUSION Uremic pruritus is not related to PTH. Substance P may act as a neurotransmitter in uremic pruritus and topical capsaicin can be used in the treatment of localized pruritus.

Ultrasound-guided cannulation of the internal jugular vein for dialysis vascular access in uremic patients.

Background: A reliable temporary vascular access is always required for hemodialysis when a permanent vascular access is not available. However, techniques for creating temporary vascular accesses remain imperfect. This study utilized the ‘SiteRite’ ultrasound device to improve both success and complication rates of jugular venous cannulation for temporary access. Methods: This prospective, comparative study recruited 104 uremic patients receiving ultrasound-guided and 86 patients undergoing landmark-guided percutaneous internal jugular venous cannulation of dual-lumen dialysis catheters. Success rate, number of puncture attempts, access time, and the complication rate of the ultrasound technique, in comparison with the landmark-guided technique, were studied. Results: The ultrasound-guided cannulation was superior to the external landmark-guided cannulation in overall success rate (99.0 vs. 86.0%, p < 0.01), success rate of the first puncture attempt (80.8 vs. 34.9%, p < 0.01), average puncture (access) times (15.8 vs. 43.7 s, p < 0.01), puncture trials (1.39 vs. 2.58, p < 0.01), and traumatic complication rate (1.9 vs. 11.6%, p = 0.015). The incidence of infective complications for the ultrasound group was not different from that of the landmark-guided groups (2.9 vs. 2.3%, p = 0.589). Conclusion: The ultrasound-guided technique offers both safety and convenience in inserting jugular venous dialysis catheters. It represents a valuable technique in creating temporary dialysis hemoaccesses.

Iron Metabolism Indices for Early Prediction of the Response and Resistance to Erythropoietin Therapy in Maintenance Hemodialysis Patients

A prospective study with 65 maintenance hemodialysis (MHD) patients on recombinant human erythropoietin (rHuEPO) therapy was conducted to assess the effect of iron balance on responsiveness. An attempt to define the predictors of erythropoietin (EPO) response and identify the specific causes of EPO resistance was undertaken in the present study. The treatment protocol consisted of two stages, the first was rHuEPO therapy for 6 months and the second was iron supplementation plus rHuEPO therapy in patients without response to EPO for the next 6 months. According to the hemoglobin (Hb) changes (increment exceeded 30% of baseline or did not exceed 15% of baseline for 3 consecutive months) and whether or not there was an achievement of target Hb level (>10.5 g/dl), all patients (n = 65) were divided into EPO-responsive (n = 20) and EPO-resistant (n = 45) groups. The EPO-resistant patients were then further stratified into iron-responsive (n = 29) and iron-irresponsive (n=16) groups. Iron metabolism and red cell indices were analyzed prior to and following rHuEPO therapy and iron supplementation.(ABSTRACT TRUNCATED AT 250 WORDS)

Renal Function in Gout Patients

Patients with gouty arthritis were examined at Veterans General Hospital to evaluate whether their renal function is impaired and to define the factor(s), if any, of renal function deterioration. A total of 152 cases were included in the study, and the patients were divided into two groups. One group (n = 80) exhibited pure gout without any associated medical problems or preexisting renal disorders. The second group (n = 72) included patients with gout and hypertension. The group with pure gout was further stratified into patients with tophi (n = 21) and those without (n = 59). Seventy-two sex- and age-matched normal adults served as the control group. We found (1) that the renal function was impaired in the pure-gout group when compared with sex- and age-matched normal individuals (serum creatinine 1.56 +/- 0.64 vs. 0.90 +/- 0.16 mg/dl, p = 0.0001; creatinine clearance 59.91 +/- 30.90 vs. 97.10 +/- 27.19 ml/min, p = 0.0001); (2) that the renal function was significantly more aggravated in patients with clinically visible tophi than in those without (gout with tophi vs. gout without tophi: serum creatinine 1.89 +/- 0.90 vs. 1.44 +/- 0.48 mg/dl, p = 0.040; creatinine clearance 47.27 +/- 31.90 vs. 64.40 +/- 29.53 ml/min, p = 0.030), and (3) that a further significant decline of the renal function was noted in gouty patients with an associated medical illness, i.e., hypertension (gout with hypertension vs. pure gout: serum creatinine 2.10 +/- 0.97 vs. 1.56 +/- 0.64 mg/dl, p = 0.0001; creatinine clearance 45.06 +/- 24.69 vs. 59.91 +/- 30.90 ml/min, p = 0.0029).(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of Intravenous Ascorbic Acid Medication on Serum Levels of Soluble Transferrin Receptor in Hemodialysis Patients

Intravenous ascorbic acid (IVAA) medication has been shown to facilitate iron release from inert depots and subsequently circumvent the defective iron utilization in chronic hemodialysis (HD) patients who are treated with recombinant human erythropoietin (rHuEPO). This study focuses on the effects of IVAA supplementation on serum concentrations of soluble transferrin receptors (TfR) on the basis of the hypothesis that an increase of labile iron in the cytosol will lead to inhibition of TfR expression. First, 138 HD patients were studied to evaluate the interrelation between serum TfR and iron status. In a stepwise multivariate analysis, serum EPO and transferrin saturation (TSAT) were the two independent predictors for serum TfR in HD patients (r(2) = 0.510, P < 0.001). Further analyses showed that the lower the serum EPO and the higher the TSAT, the lower the serum TfR in HD patients who are on maintenance rHuEPO treatment. Second, 36 HD patients were recruited in a randomized, controlled study to receive IVAA (total dose of 2000 mg) or normal saline (placebo) medication. Serum levels of TfR, EPO, and ferritin and TSAT were measured at baseline and within 7 d after starting IVAA or placebo. There were no significant changes in serum EPO and ferritin levels in patients who received either IVAA (n = 18) or placebo (n = 18). Serum TfR levels (P < 0.001) significantly declined with a parallel rise in TSAT (P < 0.05) as compared with presupplemental values within 7 d in IVAA patients before any apparent alteration in hematocrit values, but the changes were not observed in the placebo group. The trend of decreased serum TfR and increased TSAT was similar in IVAA patients with ferritin of <500 microg/L or >500 microg/L. It is concluded that ascorbic acid status can significantly decrease serum TfR concentrations and increase percentage of TSAT, probably through alterations in intracellular iron metabolism.

Improvement of Nutritional Status in Patients Receiving Maintenance Hemodialysis after Correction of Renal Anemia with Recombinant Human Erythropoietin

Despite a large body of evidence showing the beneficial effects of successful treatment of anemia with recombinant human erythropoietin (EPO) in patients with end-stage renal disease, controversy remains as to whether EPO treatment of anemia can improve the nutritional status in patients on maintenance hemodialysis. This prompted us to conduct a prospective study in 41 hemodialysis patients with basal hemoglobin less than 9 g/dl. The dose of EPO was increased for 12 weeks to achieve the target hemoglobin concentration of 10 g/dl and then titrated in the following 12 weeks to maintain the target value. Nutritional status was assessed at baseline and after 6 months of follow-up, using the global protein-calorie malnutrition (PCM) index proposed by Bilbrey and Cohen. A low global PCM score indicates better nutrition. The results showed that hemoglobin values significantly increased from 8.7 ± 0.8 g/dl at baseline to 10.7 ± 0.5 g/dl in the 6th month (p < 0.001). No significant changes were observed in the normalized protein catabolic rate and Kt/V during the study period. Global PCM scores improved from 30.0 ± 7.5 to 23.6 ± 3.1 (p < 0.001) and paralleled the correction of anemia by EPO treatment. The data were consistent with a major improvement in the nutritional markers of relative body weight, triceps skinfold, midarm circumference, midarm muscle circumference, serum albumin, serum transferrin and total lymphocyte count in the 6th month as compared to baseline. The percentages of mild and moderate-severe PCM at baseline were 32 and 58%, respectively. These percentages were significantly reduced during the 6th month to 20 and 30%, respectively (p = 0.0004). In summary, correction of renal anemia with EPO improves the nutritional status in hemodialysis patients. A postulated mechanism is that EPO may exhibit anabolic effects, with a better utilization of ingested protein.

Recombinant Human Erythropoietin Resistance in Iron-Replete Hemodialysis Patients: Role of Aluminum Toxicity

The present study was designed to investigate the impact of aluminum toxicity on the response to recombinant human erythropoietin (rHuEPO) therapy in hemodialysis patients, when iron deficiency has been corrected or excluded. We studied 39 patients on regular hemodialysis (20 males and 19 females; mean age 58.8 years), who were under maintenance rHuEPO treatment for at least 6 months, and who had stable hematocrit levels for more than 3 months. All patients had adequate iron stores and availability with serum ferritin >100 µg/l and iron saturation >25%. They were classified into two groups: 19 poor responders, who required subcutaneous rHuEPO doses >100 U/kg/week and failed to achieve the target hematocrit level of 30%, and 20 good responders, who needed doses of ≤100 U/kg/week to maintain the target level. Serum aluminum levels including basal (Albasal) and 44 h after desferrioxamine (DFO) infusion (Alpost-DFO), intact parathyroid hormone, and inflammatory and hemolytic indices were examined in both groups. The results showed that the mean weekly rHuEPO doses were significantly lower and the mean hematocrit levels higher in the good responders than in the poor responders. Although the poor responders had markedly higher mean Albasal and Alpost-DFO levels, no differences were observed in the other parameters between the two groups. Furthermore, the poor responders significantly had the greater increment in the serum aluminum levels after DFO infusion (ΔAl =Alpost-DFO – Albasal). The mean corpuscular volume had a strong inverse correlation with ΔAl in the poor response group (r = –0.711, p < 0.001). We concluded that the post-DFO rise of serum aluminum can be used as a means of estimating tissue stores. Subclinical aluminum toxicity may exhibit an inhibitory effect on erythropoietic response to rHuEPO therapy.

Mathematical Approach for Estimating Iron Needs in Hemodialysis Patients on Erythropoietin Therapy

Functional iron deficiency occurs when recombinant human erythropoietin (rHuEPO) accelerates erythropoiesis to an extent that the iron availability cannot meet the anticipated demand. Such a phenomenon will reduce the optimal response to rHuEPO. To estimate the iron needs of functional iron deficiency in hemodialysis patients on rHuEPO therapy, we utilized a mathematical method. Forty hemodialysis patients were examined in the study, and all had a baseline serum ferritin (SF) level > 100 microg/l. They were stratified into patients with a transferrin saturation (TfS) value > or = 25% (group I) and those below this value (group II). The treatment protocol consisted of rHuEPO therapy in the two groups for 6 months and iron supplement only in group II. The target hemoglobin level was 10.5 g/dl, and iron metabolism indices were analyzed prior to and following therapy. The results showed (1) in group I (n = 20) hemoglobin rose from 7.5 +/- 0.9 to 10.7 +/- 0.7 g/dl (p < 0.01) and the mean SF level declined from 1,583 +/- 997 to 968 +/- 664 mg (p < 0.01); (2) in group II (n = 20) hemoglobin also increased from 7.8 +/- 0.9 to 10.6 +/- 0.8 g/dl (p < 0.01) following iron supplement, while the SF rose from 183 +/- 70 to 326 +/- 125 mg (p < 0.01); (3) TfS was significantly elevated in group II following iron therapy (18.9 +/- 4.8 vs. 34.5 +/- 9.1%, p < 0.01), and (4) the nomogram showed a sensitivity of 80%, a specificity of 100%, a positive predictive value of 100%, and a negative predictive value of 83% in estimating the iron status before rHuEPO therapy. We conclude that SF levels reflect iron stores and that TfS < 25% is an index of functional iron deficiency. Iron supplementation is not necessary in patients with SF > 100 microg/l and TfS > or = 25%. It seems rational to provide intravenous iron in EPO-resistant patients with functional iron deficiency (SF > 100 microg/l, TfS < 25%). This paper illustrates the importance that accurate assessment of iron needs by a mathematical method would enhance treatment efficacy and avoid iron overload in hemodialysis patients on rHuEPO therapy.

Internal jugular vein haemodialysis catheter-induced right atrium endocarditis : Case report and review of the literature

We present a case of right-sided endocarditis as a life-threatening complication of having a jugular vein haemodialysis catheter inadvertently placed in the right atrium. The mechanisms of direct traumatization of the endocardium by the catheter tip and continuous inoculation of bacteria onto the endocardial surface make dual lumen catheter-induced endocarditis similar to the pathophysiology of experimental endocarditis in animals. Therefore, the catheter tip should be placed in the distal superior vena cava during cannulation. Once endocarditis is present, removal of catheters and a 4-6-week course of intravenous antibiotics guided by the sensitivity test are recommended.