Complications of laparoscopic treatment of esophageal achalasia in children

BACKGROUND/PURPOSE

The aim of this study was to evaluate the incidence and management of the complications that occurred in some children who underwent laparoscopic Heller's esophagocardiomyotomy in the authors' institutions.

METHODS

Between March 1993 and October 1998, the files of all the children with achalasia who underwent laparoscopic Heller's esophagocardiomyotomy in a community hospital in Naples, Italy, and a private hospital in Paris, France, were reviewed. A 5-port technique was used associating Heller's esophagocardiomyotomy to an antireflux surgical mechanism (Dor's or Toupet's) in all cases. Intra- and postoperative complications, as well as the postoperative outcome, were evaluated.

RESULTS

Ten laparoscopic Heller's esophagocardiomyotomies were performed in 5 girls and 5 boys with achalasia. Age ranged between 2 and 13 years. Mean operating time was 120 minutes. Hospital stay ranged between 3 and 41 days. Complications were recorded in 3 patients: in 2 an esophageal mucosal perforation and in 1 a prolonged dysphagia. Two of these complications occurred in the last patients operated on. Follow-up varied from 6 months to 6 years. All children were free of symptoms.

CONCLUSIONS

The results show that laparoscopic Heller's esophagocardiomyotomy in children is a feasible procedure. Assessment of mucosal integrity immediately after the myotomy must be performed. Complications can happen even if the operation is performed by expert laparoscopic surgeons.

Continuous tidal peritoneal dialysis (CTPD) prescription and adequacy targets

NKF-DOQI guidelines suggest a Kt/V value of 2.1 and a creatinine clearance (CRCL) value of 63 L/1.73 m2 of body surface area per week as minimum targets in continuous cycling peritoneal dialysis (CCPD). Those targets are obtained by adapting the CAPD guidelines. The aim of our study was to verify the possibility of reaching the suggested targets with continuous tidal peritoneal dialysis (CTPD) and to check target modification in this automated treatment. Eight anuric patients underwent four consecutive CTPD sessions with increasing total prescribed volumes (17 L, 22 L, 27 L, and 32 L; night 9 h; fill 2.2 L; tidal 75%, day 2 dwells). The Kt/V increase was significant (P = 0.012), unlike that of CRCL, with larger volumes. Two patients did not reach target Kt/V, and four did not reach target CRCL. The volume normalized for 1.73 m2 corresponding to DOQI targets was 19.6 +/- 2.6 L for Kt/V and 20.2 +/- 2.4 for CRCL. The overall Kt/V was 2.29 +/- 0.66 and CRCL was 57.3 +/- 16.5 L/1.73 m2. CRCL/Kt/V overall ratio was 25.6 +/- 4.7 and significantly different from the target ratio (63/2.1 = 30, P < 0.001). The CRCL/Kt/V ratio showed a significant decrease with larger volumes (P = 0.001, linear trend P < 0.001). Adequacy targets can be reached only in some patients on CTPD even with high dialysis volumes. The changes in the CRCL/Kt/V ratio in relation to dialysis volume can be considered for adaptation and evaluation of adequacy targets in automated treatments.

Day-to-day variability of adequacy indexes in peritoneal dialysis

BACKGROUND

The achievement of dialysis adequacy targets in peritoneal dialysis (PD) is assessed by the calculation of the Kt/V and creatinine clearance (C(Cr)) obtained by collecting dialysate and urine, usually two or three times a year. Prescription decisions are based on such adequacy assessments, regardless of any variability in the single measurements. The aim of our study was to assess the day-to-day variability of common dialysis adequacy parameters and to evaluate its impact on the adequacy indexes in PD.

METHODS

Twenty-four patients (14 CAPD, 10 APD) at two centres were studied by means of a triple dialysate and urine collection for a period of 1 week. Variability in the findings for a given patient was expressed by the coefficient of variation (CV%) calculated for peritoneal (p), renal, and total (tot) adequacy parameters. The target Kt/V and C(Cr) values were recalculated on the basis of variability.

RESULTS

Kt/V was less variable (CV 4.0 and 4.4% for peritoneal Kt/V (pKt/V) and total Kt/V (totKt/V) respectively) than C(Cr) (4.7 and 6.0% for peritoneal creatinine clearance (pC(Cr)) and total creatinine clearance (totC(Cr)) respectively) and proved to be a more reliable indicator of adequacy in terms of the CV. Both variability parameters became worse if renal clearance was added to peritoneal clearance. CV in APD proved to be no different from CAPD for all the parameters considered. In our centres dialysis adequacy target correction for variability provided safe values for weekly Kt/V (pKt/V=1.78-2.10 and totKt/V=1.82-2.15 target 1.7-2.0) and C(Cr)/1.73 (pC(Cr)=53.7-64.4 l and totC(Cr)=55.1-66.1 l; target 50-60 l).

CONCLUSIONS

Evaluating the adequacy of PD by means of a single measurement should take into account the weekly variability as demonstrated by a triple dialysate and urine collection. Standard adequacy targets can be corrected to allow for variability. Thus one can obtain safe values for prescription decisions based on a single collection result.

Symptoms in hemodialysis patients and their relationship with biochemical and demographic parameters

Symptoms can markedly influence the hemodialysis patients well-being and quality of life. The aim of this paper is to study the frequency of symptoms at home and how these relate to biochemical and treatment variables. Seventy-three hemodialysis patients were questioned on the absence, occasional presence or daily recurrence (score = 0, 1, 2) of 14 symptoms and a record was made of their biochemical parameters, age, time on treatment and KtIV as a function of each symptom. The following relationships were detected: thirst with high Osm and BUN; asthenia with old age and hypoalbuminemia; insomnia with hypercalcemia; hypersomnia with hypoxemia and hypernatremia; anorexia with hypokalemia; dyspnea with old age, hypernatremia and hypokalemia; dysgeusia with hypoxemia; nausea with alkalemia, hypoxemia and low BUN; vomiting with alkalemia. Pruritus, arthralgia, restless legs syndrome, cramp and tremor showed no relationships. Monitoring acid-base balance and plasma electrolytes could help to alleviate symptoms and ameliorate quality of life of hemodialysis patients.

Optimal design of a two-sample test for assessing [125I]iothalamate plasma clearance in peritoneal dialysis

BACKGROUND

Plasma clearance of a tracer in peritoneal dialysis (PD) can be used to assess treatment adequacy without labour-intensive fluid collections. Accuracy and precision of plasma clearance estimates by the bolus injection technique depend on the estimation accuracy of the area under the concentration curve and the measurement precision of plasma concentrations. The first source of error is due to oversimplified, e.g. monoexponential, descriptions of plasma disappearance curves. The second source of error arises from the propagation of measurement errors to the parameter estimates.

METHODS

The theoretical bias of parameter estimates is determined first for a monoexponential approximation of a biexponential disappearance curve and as a function of the first sampling time at which mixing is still incomplete. The precision of plasma clearance estimates, expressed as coefficient of variation, is then described as a function of the experimental variables and of the standard deviation of measurement error. This allows the determination of the optimal two-sample test that yields most precise estimates of plasma clearance.

RESULTS

The optimal two-sample schedules for assessing plasma clearance of [125I]iothalamate in PD patients vary between subjects according to individual clearances and distribution volumes. Our results suggest collecting the first sample 120 min, and the second 2-4 days, after the bolus injection.

CONCLUSIONS

The proposed two-sample test is suitable to be used in clinical routine for assessment of adequacy of PD treatment but requires a priori estimation of individual tracer kinetics and of laboratory measurement errors. A fixed design with the first sample taken after 120 min and the second sample collected 3 days after the bolus injection should yield the best performance.

Clinical validation of PD Adequest software: modeling error assessment

OBJECTIVE

PD ADEQUEST software (Baxter Healthcare, Deerfield, IL, U.S.A.) is used in peritoneal dialysis for calculating the indices of dialysis efficiency and for the mathematical simulation of the results of various dialysis regimens. The aim of our study was to quantify the modeling errors and find the methods which give best results.

DESIGN

Nonrandomized, repeated measurement, clinical validation study.

PATIENTS

The study included 78 patients on continuous ambulatory peritoneal dialysis (PD), daytime ambulatory PD, and automated PD.

MEASUREMENTS

We used 207 collections of dialysate and urine associated with peritoneal equilibration tests (PETs) performed with different glucose concentrations (1.36%, 2.27%, 3.86%). The measured urea Kt/V, creatinine clearance (CRCL) and ultrafiltration (UF) were compared with the same data simulated mathematically using the PD ADEQUEST software version 1.4.

RESULTS

The Kt/V, CRCL, and UF measured values were significantly correlated and in agreement with modeled data [concordance correlation (rc) was 0.849, 0.839, 0.625 respectively]. The errors (modeled - measured) were: Kt/V = -0.04 +/- 0.27 (p = ns), CRCL = 2.1 +/- 7.7 L (p < 0.001), UF = -121 +/- 711 mL (p = 0.016). Applying ANOVA to both the peritoneal transport data calculated by PD ADEQUEST (mass transfer area coefficient of the solutes, fluid reabsorption, and hydraulic permeability) and the modeling errors, significant differences were found in relation to the PET glucose concentrations.

CONCLUSION

PD ADEQUEST proves to be a useful instrument in peritoneal dialysis, although there is undoubtedly still room for improvement in its prediction efficacy, which is influenced by the glucose concentration used in the PET.

The use of the PD Adequest mathematical model in pediatric patients on chronic peritoneal dialysis

OBJECTIVE

To test the accuracy of the PD ADEQUEST kinetic model in calculating peritoneal transport parameters and to quantify the differences between the results of software simulations and direct measurements in order to assess the reliability of this tool in chronic peritoneal dialysis (PD) pediatric patients.

PATIENTS

Twenty-nine patients (mean age: 10 +/- 4 years; range: 4-17), 5 on continuous ambulatory PD, 4 on continuous cycling PD, 19 on nocturnal intermittent PD and 1 in nocturnal tidal PD, all free from peritonitis in the previous 2 months. Fourteen patients were anuric and 15 had a mean glomerular filtration rate of 1.79 +/- 1.23 mL/min, range 0.25-4.82.

METHODS

In all patients, 24-hour dialysate and urine collections associated to standard peritoneal equilibration test (PET) were performed using their usual dialytic regimen and fill volume (1023 +/- 159 mL/m2 BSA, range 614-1361). PD ADEQUEST kinetic parameters were compared with pediatric and adult data from literature. The measured weekly normalized total creatinine clearance (CRCL), weekly total Kt/V, and daily net ultrafiltration (UF) were compared with corresponding mathematically modeled values.

RESULTS

Kinetic parameters calculated by the PD ADEQUEST program were comparable to adult and pediatric values from previous studies after normalization for BSA. Measured and modeled CRCL and Kt/V showed a good agreement [concordance correlation (rc) 0.937 and 0.768, respectively] with limited median percentage absolute errors (11.6% and 10.2%, respectively). Ultrafiltration showed less favorable results (rc = 0.600 and median percentage absolute error 45%) probably owing to the wide variability of this parameter. When the analysis was restricted to the peritoneal component, the rc coefficients results were 0.745 for CRCL and 0.512 for Kt/V (median absolute error: 11.6% and 15.2%, respectively).

CONCLUSIONS

The overall findings of our study show that the PD ADEQUEST kinetic model can be used in pediatric patients for the calculation of kinetic indexes and for mathematical simulation of the various regimens. We also feel that the results yielded by the PD ADEQUEST program are reliable enough for this computerized mathematical model to be used in the prescription management of pediatric patients. Only UF prediction needs to be used with a certain caution on account of the marked variability of this parameter.

Evaluation of Non-Linear and Linear Mathematical Models for Creatinine and Glucose Fitting in Peritoneal Dialysis

Four non-linear and five linear models for predicting the creatinine dialysate/plasma ratio (CRD/P) and the glucose dialysate/initial concentration ratio (GLD/Do) were evaluated in a group of 31 patients on peritoneal dialysis and subjected to the peritoneal equilibration test (PET 3.86%, 240'). PET results and classification were compared to obtain a definition of patient peritoneal transport characteristics. The monomolecular and rectangular hyperbola non-linear models, the Lineweaver-Burk, Hanes-Woolf and Dadone linear transformations were considered for the CRD/P fitting. A monoexponential and two-exponential decay plus the semilogarithmic transformations were considered for the GLD/Do. These models are simple, accurate and functionally homogeneous. Further studies are advisable however on the individual peritoneal transport classification, since ∼30% of the patients were in different categories for CRD/P and GLD/Do and the fittings do not give better classification results.

Evaluation of non-linear and linear mathematical models for creatinine and glucose fitting in peritoneal dialysis

Four non-linear and five linear models for predicting the creatinine dialysate/ plasma ratio (CRD/P) and the glucose dialysate/initial concentration ratio (GLD/D0) were evaluated in a group of 31 patients on peritoneal dialysis and subjected to the peritoneal equilibration test (PET 3.86%, 240'). PET results and classification were compared to obtain a definition of patient peritoneal transport characteristics. The monomolecular and rectangular hyperbola non-linear models, the Lineweaver-Burk, Hanes-Woolf and Dadone linear transformations were considered for the CRD/P fitting. A monoexponential and two-exponential decay plus the semilogarithmic transformations were considered for the GLD/ D0. These models are simple, accurate and functionally homogeneous. Further studies are advisable however on the individual peritoneal transport classification, since approximately 30% of the patients were in different categories for CRD/P and GLD/D0 and the fittings do not give better classification results.

Calcium lactate interference in measuring creatinine in peritoneal dialysis fluids by the Jaffé kinetic method

Creatinine measurements in peritoneal dialysis fluids using the Jaffé method have poor specificity due to interfering substances. We have checked to see if calcium lactate, in addition to glucose, interferes with the Jaffé kinetic measurement. Eight samples were prepared with increasing concentrations of glucose (960-3890 mg/dL) and eight were prepared with the same glucose content plus 7 mg/dL of calcium lactate, all without creatinine; in addition, 96 samples with increasing concentrations of glucose (1500-4000 mg/dL), calcium lactate (3-7.5 mg/dL), and creatinine (0.75-4.5 mg/dL) were prepared. There was a 0.31 +/- 0.13 mg/dL glucose interference on the Jaffé kinetic measurement in the first series, with an exponential trend. Interference was greater with calcium lactate and glucose: 0.50 +/- 0.16 mg/dL with the same trend. Data from the second series confirm the overestimation: 0.54 +/- 0.05 mg/dL (32.6%) with an exponential trend. The interference of glucose, creatinine, and calcium lactate on the Jaffé kinetic measurement was obtained by multi-variate regression. The single effects of glucose2 and glucose are predominant, but both creatinine and calcium lactate have a significant effect. Our study highlights the nonlinear glucose interference on creatinine measurement with the Jaffé kinetic method and the linear interference of both calcium lactate and creatinine.

Importance of donor/recipient body weight ratio as a cause of kidney graft loss in the short to medium term

The importance of the donor/recipient body weight ratio (DRBWR) as a cause of kidney graft loss was evaluated in 112 non-diabetic, ciclosporin-treated, first cadaver kidney transplant recipients. According to the DRBWR, the patients were divided into three groups: 'low' (< or = 0.80), 'medium' (0.81-1.20), and 'high' (> 1.20). The three groups did not differ in patient or graft survival, and the DRBWR was not a predictor of graft failure at multivariate analysis (Cox models), even after only patients with graft survivals > 1 year were considered. The three groups did not differ in glomerular filtration rate (GFR) and proteinuria 6-60 months after renal transplantation. When the 55 patients with a follow-up period > 4 years were considered, no differences between groups were found in GFR or GFR evolution over time. Hypertension was significantly less frequent in group 'high' (Mantel-Cox p = 0.04), but very likely as a consequence of uneven recipient gender (an independent predictor of hypertension at multivariate analysis) distribution between groups, the significance being lost when survival curves were rebuilt by stratifying for recipient gender. DRBWR never resulted as a significant predictor of GFR at multivariate analysis when GFR values 6-60 months after transplantation were analyzed. We conclude that the DRBWR has no major effects on kidney graft function and survival in the short to medium term.

Correction of glucose concentration interference on Jaffé kinetic creatinine assay in peritoneal dialysis

Overestimation of creatinine measurement using the Jaffé kinetic method in peritoneal dialysis solutions, due to glucose interference, has been quantified and corrected through the elaboration of linear formulas obtained from 110 recovery and 301 biological tests. The added pure powdered creatinine and enzymatic method were considered as references after proven accuracy. Considering creatinine as well as glucose concentration interference, we obtained correction formulas from multiple regression application. All the computed formulas gave satisfactory corrections but different accuracy levels. The best model in biological samples was: Corrected CR = K1JafféCr + K2Glucose (all values in mg/dl) where K1 = 0.973 and K2 = -0.00035 (Rsq = 0.987, F ratio = 10,945, p = 0.00001). Applying formulas to biological samples there was a drop in accuracy, possibly explained by the presence of numerous unidentified substances in peritoneal dialysis biological samples that can amplify scatter. Every laboratory can reduce the error of the Jaffé kinetic assay by calculating their own correction formula in relation to the method and instrument used, because Jaffé kinetic assay gives different results with different kinetic windows. So, especially when applied to peritoneal dialysis fluid measurements, if a creatinine assay reference method is not available, the correction formula can be applied directly as given. Otherwise the method we have described can be followed with a well-structured creatinine recovery fest to identify and quantify assay interferences.

Peritoneal dialysis prescription: the “Clearance Peak” model

Creatinine clearance (CRCL) was studied in 20 patients on CAPD in relation to the dwell times (DT), in order to establish a personalised dialysis schedule with the best clearance (CL) results, while respecting the patient's life-style. By calculating the CRCL from the two exchanges with dwell-times of 4 and 8 hours (2 1, 2.27%), curves (2nd degree polynomial regression) were plotted with three points (Oh, 4h, 8h) for CRCL and the ultrafiltration rate (UF) as a function of the DT. The DT corresponding to the CRCL peak (CLPeak-time) was calculated for each subject with the first derivative of the function. On the basis of the CRCL obtained with the three most common DT (4h, 6h, 8h), we divided the patients into three categories (CLPeak-time <5h: “fast”, 5-7h: “normal”; >7h: “slow”) for the best CRCL correspondence of the 4h, 6h or 8h exchanges respectively. Also the 8h/4h ratio was used to determine CLPeak-time. For each of the three categories there is a corresponding dialysis schedule for the best CRCL and UF results of the exchanges with DT of 4, 6 and 8 hours, plus the theoretical calculation of the daily CRCL obtainable (“fast”: APD; “normal”: CAPD 4 exchanges/DAPD 4 exchanges; “slow”: CAPD 4 exchanges). The “CLPeak” dialysis prescription model therefore identifies the most advantageous DT for each patient by using the CRCL values of two 2.27% exchanges of 4 and 8h respectively. Functional classification into three categories may give a rational orientation to dialysis prescription in order to reach the maximum CRCL possible with the individual peritoneal transport rates.

Peritoneal dialysis prescription: the "Clearance Peak" model

Creatinine clearance (CRCL) was studied in 20 patients on CAPD in relation to the dwell times (DT), in order to establish a personalised dialysis schedule with the best clearance (CL) results, while respecting the patient's life-style. By calculating the CRCL from the two exchanges with dwell-times of 4 and 8 hours (2 I, 2.27%), curves (2nd degree polynomial regression) were plotted with three points (0h, 4h, 8h) for CRCL and the ultrafiltration rate (UF) as a function of the DT. The DT corresponding to the CRCL peak (CLPeak-time) was calculated for each subject with the first derivative of the function. On the basis of the CRCL obtained with the three most common DT (4h, 6h, 8h), we divided the patients into three categories (CLPeak-time < 5h: "fast", 5-7h: "normal"; > 7h: "slow") for the best CRCL correspondence of the 4h, 6h or 8h exchanges respectively. Also the 8h/4h ratio was used to determine CLPeak-time. For each of the three categories there is a corresponding dialysis schedule for the best CRCL and UF results of the exchanges with DT of 4, 6 and 8 hours, plus the theoretical calculation of the daily CRCL obtainable ("fast": APD; "normal": CAPD 4 exchanges/DAPD 4 exchanges; "slow": CAPD 4 exchanges). The "CLPeak" dialysis prescription model therefore identifies the most advantageous DT for each patient by using the CRCL values of two 2.27% exchanges of 4 and 8h respectively. Functional classification into three categories may give a rational orientation to dialysis prescription in order to reach the maximum CRCL possible with the individual peritoneal transport rates.

Comparison of fast peritoneal equilibration tests with 1.36 and 3.86% dialysis solutions

At present dialysis solutions with different glucose concentrations are used for the peritoneal equilibration test (PET) and Fast-PET in peritoneal dialysis (PD). We compared the results of two Fast-PETs, using 1.36 and 3.86% solutions sequentially in 30 patients on PD treatment, to obtain information on peritoneal transport (D/P-4 h) and ultrafiltration rates. Creatinine, phosphorus and urea D/P-4 h in the two Fast-PETs were not statistically different, unlike those for potassium, beta 2-microglobulin and glucose. The creatinine and phosphorus D/P-4 h values in particular proved to be uninfluenced by the different dialysis solutions. The lack of correlation between the two Fast-PET ultrafiltration values confirmed the difficulty in interpreting this parameter, above all in the case of non-homologous Fast-PETs. We obtained useful indications for comparing different Fast-PET results, but were unable to reach a decisive conclusion regarding the best of the two dialysis solutions for this test.