4 Patients and methods
5.4 Uremia control 5.4.1 Laboratory assays
Essential laboratory values are presented in Table 11. There were no statistical differences in creatinine, hemoglobin, calcium or phosphate, PTH, or cholesterol and triglyceride values between retrospectively analyzed and prospectively followed PD patients. PTH and triglyceride values seemed however to be lower in the prospective
group. BUN values were statistically lower in the prospective group (I, II).
Intact PTH levels were difficult to control in our prospective group. IPTH values in the retrospectively analyzed and in the prospectively followed PD patient groups are shown in Figure 9. In both groups, a clear tendency towards an increase in iPTH during PD can be seen. Differences between these patient groups were not statistically significant.
table 11. Laboratory values at 6 months on PD in children less than two years of age at PD onset between 1995 and 2000 (Study I) and between 2001 and 2005 (Study II).
figure 9 Percentage of patients with a plasma intact parathyroid hormone level below or over twice and thrice the upper limit of normal (ULN) during dialysis in retrospectively analyzed (I) and prospective PD patients (II). Numbers of patients above the columns.
5.4.2 Adequacy of PD
In retrospectively analyzed patients with a modified 24-hour dialysate collection, the adequacy parameters were mean urea Kt/V 3.2 ± 1.0 and mean Crcl 67 ± 23 L/week per 1.73 m2 at about nine months on PD (n=15) (I). However, the dialysate collection method was different to our prospectively studied patients (see Methods in chapter 4.2.5.2). In the prospective group, these values were mean urea Kt/V 3.3 ± 0.8 and
mean Crcl 49 ± 19 L/week per 1.73 m2 at three months (n=21),3.5 ± 0.6 and 49 ± 18 L/week per 1.73 m2 at six months (n=18), and 3.5 ± 0.8 and 49 ± 30 L/week/1.73 m2 at nine months (n=9), respectively. Patients with RRF showed no significantly higher urea purification compared with anuric patients. The Crcl levels were significantly better in patients with RRF between 2001 and 2005: 66 ± 27 L/week per 1.73 m2 compared to 44 ± 13 L/wk per 1.73 m2 in anuric patients (p<0.001) (II).
The Crcl levels in our prospectively followed PD patients were lower than targeted, in particular in anuric patients. Still, these patients grew well during PD. When our material was analyzed with the method of Ishikura et al. (2003), described in the methods section, the mean weekly creatinine Kt/V was 2.2 ± 0.9 in all patients. In anuric patients it was 1.9 ± 0.6 and 3.0 ± 1.2 in children with RRF. The determined cut-off point; a weekly creatinine Kt/V of 1.52 which corresponded to a Crcl of 60 L/
week per 1.73 m2 in male adults, was in our patient material equal to a Crcl level of 35 L/week per 1.73 m2, see Figure 10. Thus, if the child is growing and developing well, as low Crcl as 35 L/week per 1.73 m2 or over seems to be enough.
figure 10 Creatinine clearances in 21 prospective PD patients less than 2 years of age at onset of PD. Patients with residual renal function are marked with empty circles and anuric patients with filled circles. Fit line represents all measurements. Vertical dashed line shows weekly creatinine Kt/V of 1.52 and horizontal line corresponds to a creatinine clearance value of 35 L/week 1.73 m2 (unpublished data).
5.5 Complications of PD
5.5.1 Catheter–related complications and hernias
The need for surgical intervention for PD catheters, catheter-related infections, peritonitis. and hernias before PD onset and during PD in retrospectively analyzed and prospectively followed PD patients are presented in Figure 11. There were no significant differences in the number of patients having catheter problems or hernias between the groups. There were less catheter exchanges in the prospective PD patient group but the difference was not statistically significant (I, II).
figure 11 Catheter repositions and exchanges, tunnel and exit-site infections, peritonitis, and hernia in patients under age 2 at PD initiation (n=23, study I; n=21, study II, unpublished data).
5.5.2 Peritonitis
Peritonitis frequency is shown in Tables 10 and 12 (I, II). Peritonitis incidence and causative organisms are presented in Table 12. Prospectively followed PD patients had less peritonitis, but the difference in peritonitis incidence was not statistically significant. However, more prospectively followed PD patients were peritonitis free during the whole PD period compared to retrospectively analyzed patients (p=0.036) (I, II and unpublished data). Staphylococcus aureus was a frequent organism in the prospective group and 86% of these infections were detected in two patients, whom
both experienced three bouts of peritonitis. In the families of these patients, nasal carriers of S. aureus were found (unpublished data).
table 12. Causative organisms of peritonitis in patients under two years of age on PD between 1995 and 2000 (I), and between 2001 and 2005 (II and unpublished data [causative organisms])
5.5.3 Intravascular volume status
Blood pressures, plasma ANP-N and BIA values, linear heart dimensions, and LV mass-for-height Z-scores of our prospective PD patients are presented in Table 13.
At a stable stage on PD, at 3 months after PD initiation, high plasma ANP-N (n=19) correlated well with both systolic and diastolic hypertension (r=0.59, p=0.007 and r=0.57, p=0.011). LVH (Z-scores, n=19) also correlated well with both systolic and diastolic hypertension (r=0.67, p=0.002 and r=0.54, p=0.017) at three months on PD but not with plasma ANP-N. LVEDD and systolic hypertension (n=15) showed a good correlation at 3 months (r=0.62, p=0.013). All these preceding correlations of about the same magnitude were also seen at baseline and at 6 months on PD (II).
BIA RI correlated only in the beginning of PD with LVEDD (n=12, r=0.59, p=0.045) (unpublished data). LVEDD diminished significantly between baseline and 3 months (p=0.002), as well as between baseline and 6 months (p=0.024). The proportion of patients with LVH (counted with Z-scores) decreased during PD. The improvement was statistically significant (p=0.016; PD start vs. 3 months and p=0.035; PD start
Antihypertensive medication was needed in 70% of the retrospectively studied PD patients at some point during PD, while the percentage was only 33% in our prospective group (I, II).
Prospectively followed patients had no clear periods with clinical hypovolemia.
Nor did we find data about clinically significant periods of hypovolemia in the patient records of the retrospectively analyzed PD patients (I, II).
In conclusion, LVH decreased in the prospectively followed patients with time during PD. However, many patients still had high blood pressures during PD.
table 13. Blood pressures and patients exceeding the 95th percentile, plasma ANP-N and patients exceeding the value 3 nmol/L, and BIA resistance, resistance index, and reactance. Under the linear heart dimensions and LV mass-for height Z-scores and percentage of patients exceeding the 95th percentile (II and unpublished data [BIA values]).