Could mini-PET be used to instead of 4 h original-PET to assess peritoneal permeability in children on peritoneal dialysis?

Peritoneal equilibration testing: Your questions answered

The peritoneal equilibration test (PET), first described in 1987, is a semiquantitative assessment of peritoneal transfer characteristics in patients undergoing peritoneal dialysis. It is typically performed as a 4-h exchange using 2.27/2.5% dextrose dialysate with serial measurements of blood and dialysate creatinine, urea, and glucose concentrations. The percentage absorption of glucose and D/P creatinine ratio are used to determine peritoneal solute transfer rates. It is used to both help guide peritoneal dialysis prescriptions and to prognosticate. There are several derivative tests which have been described in the literature. In this review, we describe the original PET, the various iterations of the PET, the information gleaned, and the use in the setting of poor solute clearance and in the diagnosis of membrane dysfunction, and limitations of the PET.

Comparative Assessment of Peritoneal Membrane Characteristics in Patients on Continuous Ambulatory Peritoneal Dialysis Using Standard Peritoneal Equilibration Test and Fast Peritoneal Equilibration Test

Background

Evaluation of peritoneal membrane permeability in patients on continuous ambulatory peritoneal dialysis (CAPD) is crucial in prescribing treatment regimens. This study evaluated peritoneal membrane characteristics in patients on CAPD using standard peritoneal equilibration test (PET) and fast PET.

Methods

A prospective observational longitudinal study included patients on CAPD with no symptoms of peritonitis for at least 4 weeks before the PET. Both, standard and fast PET were performed using 2.5% glucose-containing dialysate. The dialysate and plasma (D/P) creatinine ratios at each time point (i.e., 0 h, 2^nd h, and 4^th h) in standard and at 4^th hour only in fast PET were determined. Patients were classified according to D/P creatinine value as high, high-average, low-average, low transporter. The follow-up period was 6 months and changes in membrane characteristics were compared again to revalidate the efficacy of fast PET.

Results

A total of 50 patients between 41 and 70 years of age were enrolled. The majority had diabetic nephropathy (40%) and chronic glomerulonephritis (28%). Based on transport type, a significant positive correlation was observed between the D/P creatinine ratio of baseline standard PET I and fast PET I (r = 0.992, P ≤ 0.05) and standard PET II and fast PET II (r = 0.969, P ≤ 0.05) done after 6 months. The results of the PET and transport category after 6 months were similar in 82% cases determined by fast PET and 98% cases determined by the standard pet. There was significant agreement between both the methods of PET (K value = 0.872, P < 0.001). A significant (P ≤ 0.001) correlation was observed between standard PET I and standard PET II transport status.

Conclusion

Fast PET is a good alternative for assessing peritoneal membrane characteristics especially in the setting of less availability of resources and is a less cumbersome procedure as compared to standard PET.

Comparison of three PET methods to assess peritoneal membrane transport

The peritoneal equilibration test (PET) is the most widespread method for assessing water and solute transport across the peritoneal membrane. This study compared three methods: traditional PET (t-PET), mini-PET, and modified PET (mod-PET). Non-diabetic adults (n=21) who had been on peritoneal dialysis (PD) for at least three months underwent t-PET (glucose 2.5%-4 h), mini-PET (glucose 3.86%-1 h), and mod-PET (glucose 3.86%-4 h) to determine dialysate-to-plasma concentration ratio (D/P) for creatinine and dialysate-to-baseline dialysate concentration ratio (D/D0) for glucose. Agreement between methods regarding D/P creatinine and D/D0 glucose was assessed using analysis of variance (ANOVA), Pearson's correlation coefficient, and Bland-Altman analysis. D/P creatinine differed between t-PET and mini-PET (P<0.001) and between mod-PET and mini-PET (P<0.01) but not between t-PET and mod-PET (P=0.746). The correlation of D/P creatinine with t-PET vs mod-PET was significant (r=0.387, P=0.009) but not that of t-PET vs mini-PET (r=0.088, P=0.241). Estimated bias was −0.029 (P=0.201) between t-PET and mod-PET, and 0.206 (P<0.001) between t-PET and mini-PET. D/D0 glucose differed between t-PET and mod-PET (P=0.003) and between mod-PET and mini-PET (P=0.002) but not between t-PET and mini-PET (P=0.885). The correlations of D/D0 glucose in t-PET vs mod-PET (r=−0.017, P=0.421) or t-PET vs mini-PET (r=0.152, P=0.609) were not significant. Estimated bias was 0.122 (P=0.026) between t-PET and mod-PET, and 0.122 (P=0.026) between t-PET and mini-PET. The significant correlation of D/P creatinine between t-PET and mod-PET suggested that the latter is a good alternative to t-PET. There was no such correlation between t-PET and mini-PET.