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Brief Reports Indian Pediatrics 2002; 39:375-380 |
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Hemodialysis in Children |
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Renal replacement therapy is required for patients who have acute or chronic renal dysfunction, which results in serious uremic toxicity or derangement of electrolytes and acid base balance. Commonly used renal replacement therapies include intermittent peritoneal dialysis, continuous ambulatory peritoneal dialysis (CAPD) and hemodialysis. In children, standard dialysis modalities are temporary measures to maintain fluid, nutrition and electrolyte balance. The ultimate goal of treatment in end stage renal disease is renal transplantation. Whereas intermittent peritoneal dialysis is commonly used in acute renal failure, hemodialysis can be used for both short-term and prolonged renal replacement. Intermittent peritoneal dialysis is inexpensive and can be easily performed at majority of hospitals. However, hemodialysis requires expensive equipment, technical expertise and intensive monitoring that may not be available at pediatric departments in developing countries. There is little information on the experience of hemodialysis in children in our country(1). We report our experience with 53 children, aged between 2 and 16 years who underwent hemodialysis. Subjects and Methods One hundred and twelve children required renal replacement therapy for either acute or chronic renal failure in the Department of Pediatrics from January 1995 to December 1999. Majority of patients were sick and required emergency dialysis. Peritoneal dialysis was easy to initiate, particularly in sick children with hemo-dynamic instability, fluid overload and hypoxia. It was thus the initial renal replacement therapy in almost all cases. Hemodialysis was instituted in patients more than 2 years of age who continued to require dialysis support beyond two weeks. Patients younger than 2 years were managed with intermittent peritoneal dialysis. Vascular access for hemodialysis was obtained using temporary double lumen catheters (Medcomp, PA, USA; Fresenius, Hamburg, Germany), inserted in femoral, subclavian or internal jugular veins. Permanent vascular access, e.g., cuffed catheters, arteriovenous shunt and fistula were used in patients who required prolonged dialysis, when renal transplantation was not possible or delayed. The size of the catheter was based on the weight of the patient. Children weighing 10-15 kg had 9 Fr, children between 16-20 kg had 10 Fr and those weighing more than 20 kg had 11 Fr catheter inserted percutaneously, using Seldinger technique. The position of the subclavian catheter was confirmed by a chest radiograph. Each port of the catheter was filled with heparin (2500 U/ml) following insertion and after each dialysis session. Catheters were not irrigated between hemodialysis sessions and prophylactic antibiotics were not used. Catheter infection was diagnosed in the presence of fever and rigors during dialysis, with resolution of symptoms following antibiotic therapy. Catheters were removed in patients in whom symptoms of infection persisted or when the blood flow through the catheter was insufficient. Hollow-fiber dialyzers made of cupro-phane or cellulose acetate membrane (Terumo, Japan; Focus, USA) were used. Each dialyzer was used for 4 hemodialysis sessions, provided it could be washed clean without significant thrombosis of the fibers. The size of the dialyzer was 75-100% of the body surface area of the child. The extracorporeal circuit in patients weighing less than 15 kg was primed with normal saline or blood before starting the dialysis. Hemodialysis sessions were performed on an ultrafiltration controlled dialysis machine (Fresenius 2000A, Hamburg, Germany). A separate hemodialysis machine was used for hepatitis B surface antigen positive patients. Patients were weighed before and after each hemodialysis session. Patients who had edema or interdialytic weight gain were subjected to ultrafiltration to remove excess body fluid. A maximum ultrafiltration rate of 500 ml/h was used in severely edematous patients. Patients with hemoglobin below 7 g/dl received blood transfusion during dialysis. Each dialysis session ranged from 3-4 hours. Most patients received on an average, 8-10 hours of hemodialysis per week, in 2-3 dialysis sessions. All patients were dialyzed with acetate dialysis fluid; bicarbonate dialysis was not performed. Standard supportive therapy was instituted for renal failure. Blood urea and electrolytes were measured before and after a hemodialysis session, once a week, and the urea reduction rate (URR) calculated as follows(2):
Pre-dialysis urea - Post dialysis urea Results Fifty-three children (35 boys) underwent 835 hemodialysis sessions over the 5-year period. The median age at initiation of dialysis was 11 yr; range 2.2-16 yr. Four patients were aged below 4 years, 23 between 5 and 9 years, and 26 above 10 years. Their clinical characteristics are shown in Table I. Eighteen patients weighed less than 20 kg. Twenty patients underwent hemodialysis for acute renal failure. Of these, 13 had rapidly progressive renal failure, 3 each had acute tubular necrosis and hemolytic uremic syndrome and one had acute-on-chronic renal failure. In 33 patients, dialysis was initiated for end stage renal failure. The underlying cause of end stage renal failure included chronic glomerulonephritis in 12, reflux nephropathy in 11, obstructive uropathy in 8 and renal dysplasia in 2. Fifty-three (6.3%) hemodilaysis sessions were performed for emergencies such as severe hyperkalemia, hypertensive crisis, congestive heart failure and uremic encephalopathy.
The subclavian vein was used for dialysis in 49.3% sessions, femoral vein in 38.2% and internal jugular vein in 10.2% sessions. An arteriovenous shunt or fistula was used for 2.3% sessions. The mean (SD) blood flow rate to the dialyzer was 123 (31.3) ml/minute, dialysate flow 500 ml/min, ultrafiltration rate 321 (159.3) ml/hr and fluid removal 911 (532) ml/session. The median heparin dose used during dialysis was 45 U/kg/hr given as bolus injection. The mean (SD) urea reduction rate was 0.50 (0.09). Complications during dialysis included vomiting in 32.8% sessions, hypotension in 10.2%, hypertension in 8.2% and rigors in 6.2%. Rare complications were blood leak from catheter exit site (8 episodes), dialyzer thrombosis and dialyzer blood leak (4 episdoes each), and air embolism and hypothermia (one episode each). Three patients had headache, vomiting and alteration of sensorium within 24 hours of dialysis. They had rapid reduction in blood urea levels and no other cause for neurological dysfunction could be identified. These patients were considered to have dialysis dysequilibrium syndrome, which improved over 48 hours. None of the patients had seizures during dialysis. The cost of material for each dialysis session with dialyzer reuse was approximately Rs. 700-900. Vascular Access Seventy-four vascular accesses were created in 53 patients. Of 72 central venous catheters, 47 were femoral catheters, 23 subclavian catheters and 2 cuffed permanent internal jugular catheters. Arteriovenous fistula and arteriovenous shunt were used in one patient each. Complications of venous catheterization included thrombosis and limb swelling in 2 patients, and femoral hemorrhage, hemo-thorax, mediastinal hematoma and delayed phrenic nerve palsy in one patient each. The subclavian catheter was accidentally placed in the internal jugular vein in two patients. Twenty-six episodes of catheter infection occured in 15 patients. P. aeruginosa was grown in 12 patients, and Klebsiella spp., S. aureus and E. coli in one case each. The median duration for which femoral and subclavian catheters were used was 14.8 (range 3-18) and 26.5 (range 9-210) days, respectively. Most femoral catheters were electively removed and replaced by a catheter in the subclavian or internal jugular vein. Seven subclavian catheters were functional for more than 6 weeks. The reasons for subclavian catheter removal (n = 17) included inadequate flow in 6 patients, infection in 5 and accidental dislodgement in 2. Four catheters were removed following renal transplantation. Outcome The median duration of dialysis was 36 days (range 7 days-13.2 months). Eight patients were dialyzed for less than one month, 38 for 1-6 months and 7 for more than 6 months. The outcome of patients is shown in Table II. Four patients with rapidly pro-gressive glomerulonephritis and 2 with acute tubular necrosis recovered. Two and 7 patients with rapidly progressive glomerulo-nephritis progressed to chronic renal failure and end stage renal failure, respectively. Eight patients died while on hemodialysis. Of these, 4 died due to pulmonary edema and one each due to septicemia and cardiac arrhythmia. Two patients with acute renal failure due to diethylene glycol poisoning succumbed to toxic encephalopathy. Twenty-six patients opted out of dialysis due to financial constraints. Eleven patients underwent live-related renal transplantation.
Table II__Outcome of Hemodialyzed Patients Discussion Renal replacement therapy, in patients with renal failure, may be provided by peritoneal or hemodialysis depending on the patient’s age, duration of renal failure, coexisting illnesses and availablity of resources and technical personnel(3). The proportion of patients treated by either of the dialysis modality varies in various centers and countries. Peritoneal dialysis is simple, safe and easily adapted for use in children of all sizes and ages. Inter-mittent peritoneal dialysis is recommended for children with acute renal failure who usually show recovery of renal function within 2-3 weeks. Intermittent peritoneal dialysis cannot be used in patients requiring prolonged dialysis, where CAPD or hemodialysis is preferred. CAPD provides near steady-state biochemical control with no risk of dysequilibrium syndrome, minimal need for dietary and fluid restrictions and freedom from repeated dialysis needle puncture. CAPD exchanges are carried out 4-5 times a day with very meticulous attention for maintaining asepsis. Parents need to be explained and trained about the techniques for performing exchanges and troubleshooting. Despite adequate precautions, such patients are at signification risk for recurrent episodes of peritonitis(4). The procedure of CAPD requires active cooperation from the family and dedicated trained nursing personnel. Smaller dialysate bags are not freely available in our country. Thus, adult bags have to be used, which result in wastage of dialysis fluid and increased cost. Patients with end stage renal failure are usually managed by hemodialysis at our center. Most parents find hemodialysis more convenient. It is considerably less expensive as compared to CAPD in our country. The procedure is performed, 2-3 days a week, in the hospital. Each session lasts for 3-4 hours and patients are usually discharged thereafter. Hemodialysis may also be safely and effectively used for managing patients with acute renal failure, who fail to show recovery of renal function. In comparison to adults, the procedure of hemodialysis is technically more difficult in children and requires close monitoring to prevent complications. Dedicated pediatric hemodialysis units with skilled nursing and technical staff are necessary to provide safe and effective hemodialysis for children. A small proportion of children with end stage renal failure undergo prolonged hemodialysis(5). Children on long-term hemodialysis show subnormal growth, poor quality of life and delayed sexual maturation. The goal of treatment in children with end stage renal disease is renal transplantation(6). In the present study, prolonged dialysis was uncommon because regular hemodialysis was usually provided to patients with acute renal failure or those with end stage renal failure awaiting renal transplantation. A large proportion of patients stopped dialysis treatment due to financial reasons. A high cost of hemodialysis in relation to per capita income and lack of state funded or insurance-linked end stage renal disease treatment programs, in our country, is a constraint for long-term dialysis(7). Patients who died due to uremic complications complied poorly with the dialysis prescriptions. Kurian et al. also observed a similar drop out of patients from a hemodialysis program in south India(1). Common complications encountered during dialysis included hypotension, hyper-tension and vomiting(8). Dysequilibrium syndrome and accidents such as hemorrhage and air embolism were rare. A sudden fall in blood pressure, requiring infusion of fluids, has been reported to occur in 10-11% patients(8). Hypertension was seen in a significant proportion of our patients. Common causes of intradialytic hypertension are severe preexisting hypertension, volume overload, renin-induced hypertension due to overzealous ultrafiltration and removal of antihypertensive drugs during dialysis. The maintenance of a satisfactory vascular access is a major technical problem faced by pediatric hemodialysis units. Percutaneously inserted central venous catheters are the commonest vascular access for pediatric hemodialysis. Majority of these catheters are inserted in the subclavian vein(9). Though an arteriovenous fistula is preferred for prolonged dialysis(10), it is technically difficult to create in small children and requires longer maturation time as compared to adults. Since most of our patients were dialyzed for less than 6 months, we preferred to use temporary central venous catheters. Catheterization of the femoral vein was safe and technically possible in most cases. Thus, this was the initial vascular access in most patients. The average duration of use of femoral and subclavian catheter was similar to other reports(11,12). Infection (21.7%) and thrombosis (26.1%) were the chief reasons for catheter removal, as previously reported(9). In summary, our experience suggests that hemodialysis is a safe and effective renal replacement therapy in children with acute renal failure and end stage renal disease requiring support to transplantation. Central venous catheters provide useful vascular access for hemodialysis but their prolonged use is limited by infection and thrombosis. Contributors: PH and AB analyzed the data and drafted the manuscript. AB will act as the guarantor of the study. MK and MM enrolled the patients and supervised the procedure. Funding: None. Competing interests: None stated.
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