Biomedical subjects

L Ponferrada

Publications and source records attributed to L Ponferrada.

7 recordsLinked to original sources

PubMed1994

Lean body mass estimation by creatinine kinetics.

A new technique for estimating lean body mass (LBM) from creatinine kinetics has been developed. It is based on the principle that creatinine production is proportional to LBM and that, in the steady state, creatinine production is equal to the sum of creatinine excretion (urinary and dialytic) and metabolic degradation. This technique was applied to 17 normal subjects, 26 stable, chronic hemodialysis (HD) patients, and 71 stable, chronic peritoneal dialysis (PD) patients. In the HD group, LBM was also determined by bioimpedance in 11 patients and calculated from total body water, measured as the volume of urea distribution of a sterile urea infusion, in 15 patients. In normal subjects and in the PD group, LBM was assessed by creatinine kinetics as well as by bioimpedance, near infrared, and anthropometric techniques. In the HD patients, LBM by creatinine kinetics correlated significantly with LBM from total body water and the bioimpedance technique. There was no statistical difference between the total body water and creatinine kinetics techniques, but the bioimpedance values were systematically higher than those obtained by the kinetic technique. In the PD group and in normal volunteers, LBM values by creatinine kinetics correlated significantly with the other methods but were lower. Forty-seven percent of the HD patients and 66% of the PD patients had significantly lower LBM by creatinine kinetics than expected for their sex and age. Estimation of LBM by creatinine kinetics is proposed as a simple and convenient technique for the routine nutritional assessment of dialysis patients.

Anthropometry↗

PubMed1993

Age and indices of adequacy and nutrition in CAPD patients.

We have examined the correlations of age with 95 demographic, clinical, and laboratory parameters in a continuous ambulatory peritoneal dialysis (CAPD) population. Significant inverse correlations were found with lean body mass, dialysate creatinine concentration, serum creatinine concentration, and dialysate creatinine nitrogen output in grams per week; all these findings are compatible with the well-known decrease in muscle mass with aging. Urea nitrogen output in dialysate and urine predicts Kjeldahl nitrogen output in urine and dialysate applying the Randerson equation similarly in older and younger CAPD patients. The relationship of normalized net protein catabolic rate to weekly urea clearance normalized to total body water is similar for older and younger CAPD patients. Older and younger patients have similar values for serum albumin concentration. In conclusion, the findings suggest that comparable weekly creatinine clearances should yield much lower serum creatinine concentrations in older patients. Poor protein intakes in the elderly should not be attributed to age if weekly urea clearances are low. Increases in protein intake in response to increases in urea clearances are similar in older and younger CAPD patients.

Adult↗

PubMed1993

Home visit effectiveness for peritoneal dialysis patients.

Medicare regulations require follow-up home visits to home dialysis patients, yet routine home visits require a lot of personnel time. The effectiveness of home visits was evaluated by a nurse, dietitian and social worker using a questionnaire. Thirty-six patients were evaluated during an 18-month period. Collectively the team documented an average of 10 pertinent observations per visit and made an average of 4 recommendations for change. Staff members gained new information about the patient as indicated by the fact that they changed their rankings on 5 of 15 parameters following the home visit. The home visit policy that recommended an annual home visit was revised to recommend a single home visit for each new peritoneal dialysis patient. Further visits are performed only if significant problems are identified.

Adult↗

PubMed1993

Cross sectional assessment of weekly urea and creatinine clearances and indices of nutrition in continuous ambulatory peritoneal dialysis patients.

OBJECTIVE: To perform a cross sectional analysis in 71 patients on continuous ambulatory peritoneal dialysis (CAPD) to identify significant correlations of weekly small solute clearances and indices of nutritional status with each other and with patient demographics and other commonly monitored clinical and laboratory parameters. DESIGN: This was a retrospective, cross sectional analysis in 71 patients on CAPD from less than 1 to 105 patient-months (average, 20 months). SETTING: An outpatient CAPD program. PATIENTS: All patients on CAPD in our program at the time of the study willing to undergo the clearance and nutritional status measurements. INTERVENTIONS: No interventions other than the monitoring of their status. MAIN OUTCOME MEASURES: Weekly small solute clearances, dietary protein intake, serum albumin, lean body mass, net protein catabolic rate, and urinary and dialysate nitrogen. RESULTS: Weekly Kt/V urea (weekly urea clearance normalized to total body water) of at least 1.7 and weekly total creatinine clearances (liter/week/1.7 m2) of at least 50 are associated with net protein catabolic rates (PCR) greater than 0.9 g/kg of normalized body weight in average CAPD patients. Kt/V urea and net PCR correlate significantly with serum albumin. High transporters identified by the peritoneal equilibration test have greater albumin losses and lower serum albumin concentrations. Estimates of lean body mass correlate significantly with serum albumin and net PCR; lean body mass correlates significantly and inversely with age. CONCLUSIONS: Greater small solute clearances are associated with better nutritional status.

Adult↗

PubMed1990

Defining adequacy of CAPD with urea kinetics.

The purpose of this paper is to explore the validity of applying urea kinetic indices to CAPD. According to the peak concentration hypothesis, the values of Kt/V required for adequate dialysis are lower for CAPD than for hemodialysis because of the continuous steady state nature of CAPD. Pilot clinical studies were undertaken in 19 patients to correlate the (Kt/V)urea index with clinical assessment of adequacy based on a 12 parameter score. The data shows that the correlation between serum urea nitrogen (Kt/V)urea and protein catabolic rate (PCR) are in keeping with the theoretical predictions of the urea kinetic model. PCR and dietary protein are well correlated. Also, PCR and Kt/V had a high degree of positive correlation. Serum creatinine was inversely correlated with (Kt/V)creatinine. In 74% of the patients, the clinical assessment of adequacy was in agreement with the (Kt/V)urea domains of adequacy established from the peak concentration hypothesis and the urea kinetic model. The lack of correlation in the remaining 26% is being investigated.

Blood Urea Nitrogen↗

PubMedDate not supplied

Cross-sectional assessment of weekly urea and creatinine clearances in patients on continuous ambulatory peritoneal dialysis.

In 55 patients on continuous ambulatory peritoneal dialysis, the authors determined daily renal and dialysate clearances of urea nitrogen (CUN) and creatinine (CCr). Results are expressed as weekly CUN in liters (Kt) divided by liters of total body water determined from a nomogram (V). The authors calculated weekly CCr as the weekly dialysis clearance plus the average of renal CUN and CCr (to correct for creatinine secretion); they normalized total weekly CCr to 1.73 m2 body surface area. Mean weekly Kt/V and CCr were 2.1 and 65.2, respectively. Mean dietary protein intake by dietary survey was 0.85 g/kg body weight. Protein catabolic rate (PCR) calculated from urea kinetics was 0.94 g/kg standardized weight (V/0.58); PCR was significantly (p < 0.01) correlated with Kt/V (r = 0.53). The authors used linear regression to determine PCR, as follows: PCR = 0.80 [weekly Kt/V]/3 + 0.39. This slope is nearly 1.5 times that reported for the relationship of PCR to [weekly Kt/V]/3 in hemodialysis patients. Eighty-two percent of patients on continuous ambulatory peritoneal dialysis had more than the targeted minimum weekly Kt/V of 1.7, 71% had a weekly CCr more than the targeted minimum of 50, and 75% had a PCR > 0.8 g/kg/day. In support of the hypothesis that Kt/V requirements are related to peak concentration control rather than to time averaged blood urea nitrogen, patients on continuous ambulatory peritoneal dialysis have a higher PCR at given Kt/V values compared to hemodialysis patients. These patients are more likely to have a PCR > 0.8 if weekly Kt/V > 1.7.

Blood Urea Nitrogen↗

PubMedDate not supplied

Repair of chronic peritoneal dialysis catheter.

BACKGROUND: Damage to the peritoneal dialysis catheter may be due to wear from long-term use, exposure to antibacterial agents (strong oxidants), and accidental injury from sharp objects. Repair of such catheter, if not associated with subsequent complications, would extend catheter life and reduce costs and patient inconvenience related to catheter replacement. OBJECTIVE AND DESIGN: Retrospective analysis of seven peritoneal catheters repaired 11 times over a 15-year period by splicing the old catheter with an extension tube using the Peri-Patch Repair Kit (Quinton Instrument Co., Bothwell, WA, U.S.A.). RESULTS: The life of these seven catheters was extended by a mean of 26 months (range 1-87 months), without increasing infection rates after splicing. The peritonitis rate after catheter splicing was 0.40 per year, not higher than the overall rate (0.76 per year) in our center during the same time period. Exit-site infections occurred in 6 patients after catheter splicing. Only one infection was related to trauma during the procedure and resulted in chronic exit infection; the catheter was eventually removed. In this patient, damage to the catheter was less than 1.5 cm from the exit site. CONCLUSIONS AND RECOMMENDATIONS: Splicing of the damaged peritoneal catheter, if properly done, is a safe procedure and can significantly prolong catheter life. We recommend that measures to prevent catheter damage, such as avoiding the use of scissors and other sharp objects, should be emphasized during the initial patient education and training. Alcohol and iodine should not be used on silicone rubber catheters. We suggest that the patient should report catheter damage immediately and come to the clinic within a few hours for catheter splicing (if possible) and prophylactic antibiotic to prevent peritonitis. Finally, we recommend that repair of the catheter should not be attempted if the breakage is less than 2 cm from the exit site, unless done as an emergency procedure if immediate catheter replacement cannot be performed.

Adult↗