Impact of fluid overload on blood pressure variability in patients on peritoneal dialysis

Figures & data

Figure 1. Body weight changes during 1-year follow-up.

Table 1. Clinical data at baseline in different volume groups (N = 175).

Parameters	Normal volume (OH ≤ 2L)	Mild overload (2L < OH < 4L)	Severe overload (OH ≥ 4L)	p Value
	N = 91	N = 51	N = 33
Age (years)	53.7 ± 15.7	54.4 ± 13.4	52.6 ± 11.3	0.04
BMI per (kg/m^2)	23.1 ± 9.9	22.8 ± 2.6	23.3 ± 3.2	0.15
Hemoglobin (g/L)	114.4 ± 14.7	108.9 ± 13.5	102.8 ± 16.9	<0.01*
Albumin (g/L)	36.1 ± 4.3	33.7 ± 3.7	34.7 ± 4.1	0.15
Triglycerides (mmol/L)	2.1 ± 1.2	1.6 ± 0.6	1.8 ± 1.2	0.06
Cholesterol (mmol/L)	4.9 ± 0.9	4.4 ± 1.1	4.9 ± 1.1	0.97
Uric acid (mmol/L)	375.9 ± 73.2	379.8 ± 59.8	384.6 ± 72.1	0.45
Calcium (mmol/L)	2.3 ± 0.2	2.4 ± 0.1	2.3 ± 0.2	0.42
Phosphorus (mmol/L)	1.4 ± 0.4	1.6 ± 0.5	1.7 ± 0.5	<0.01*
PTH (pg/mL)	253.3 ± 203.1	280.9 ± 271.1	326.2 ± 236.1	<0.01*
Sex (male)/n (%)	47 (51.6%)	30 (58.8%)	28 (84.8%)	<0.01*
Diabetes/%	6 (6.60%)	5 (9.80%)	7 (21.20%)	<0.01*
SGA scores/%	86.10%	71.80%	54.10%	0.03*

BMI: body mass index; PTH: parathyroid hormone; OH: overhydration; SGA: subjective global assessment. P-values refer to the overall difference across categories. *p < 0.05 was considered statistically significant.

Figure 2. Linear regression for the association between OH values and BPV of SBP% (A) and DBP% (B).

Table 2. Comparation of blood pressure and variability in different groups.

Parameters	Normal volume	Mild overload	Severe overload	p Value
	(OH ≤ 2L)	(2L < OH < 4L)	(OH ≥ 4L)
	N = 91	N = 51	N = 33
SBP (mmHg)	137.8 ± 14.2	142.1 ± 7.5	151.8 ± 9.8	0.06
DPB (mmHg)	83.3 ± 16.3	83.4 ± 3.5	83.5 ± 7.1	0.08
BPV of SBP%	7.76 ± 2.93%	9.23 ± 3.33%	12.74 ± 6.34%*	<0.01*
BPV of DBP%	7.72 ± 3.16%	8.7 ± 5.43%	12.22 ± 6.12%*	<0.01*

SBP: systolic blood pressure; DPB: diastolic blood pressure; BPV: blood pressure variability; OH: overhydration. P-values refer to the overall difference across categories. *p < 0.05 vs. normal volume group (OH ≤ 2L).

Table 3. Peritoneal dialysis related parameters and medications(N = 175).

	Normal volume (OH ≤ 2L)	Mild overload (2L < OH < 4L)	Severe overload (OH ≥ 4L)	p Value
	N = 91	N = 51	N = 33
Dialysis-related parameters
Fast plasma glucose(mmol/L)	4.9 ± 1.6	4.8 ± 1.9	5.2 ± 2.1	0.30
Glucose exposure(g/24h)	142.5 ± 25.2	150.8 ± 24.8	159.3 ± 19.2	0.25
Total Kt/V	2.48 ± 0.84	2.12 ± 0.43	2.0 ± 0.5	<0.01*
CCr (ml/min)	69.24 ± 24.92	56.30 ± 11.20	50.30 ± 17.40	<0.01*
Residual GFR (ml/min)	2.39 ± 0.74	2.10 ± 0.29	2.0 ± 0.14	<0.01*
Transport status
(high average%)	24 (24.6%)	16 (31.4%)	15 (46.2%)	<0.01*
nPCR (g/kg/day)	0.98 ± 0.23	0.89 ± 0.21	0.84 ± 0.17	<0.01*
Fluid removal
Urine output(L/day)	0.64 ± 0.4	0.25 ± 0.14	0.17 ± 0.13	<0.01*
Ultrafiltration(L/day)	0.57 ± 0.28	0.83 ± 0.31	0.82 ± 0.38	0.32
Total fluid removal
(L/day)	1.21 ± 0.43	1.08 ± 0.31	0.99 ± 0.28	0.04*
Drugs
Prescribed diuretics (%)	12 (13.2%)	9 (17.6%)	9(27.2%)	<0.01*
Numbers of antihypertensive drugs	1.9 ± 1.7	3.2 ± 1.1	3.7 ± 0.9	<0.05*

Kt/V: urea clearance index; Ccr: creatinine clearance; nPCR: normalized protein catabolic rate; OH: overhydration. P-values refer to the overall difference across categories. *p < 0.05 was considered statistically significant.

Table 4. Parameters related to BPV in different volume groups.

Parameters	OR (95% CI)	p Value
Diabetes/%	0.249 (0.116–0.537)	<0.01*
Phosphorus (mmol/L)	0.323 (0.185–0.563)	<0.001*
PTH (pg/mL)	0.372 (0.214–0.647)	<0.001*
Kt/V	3.403 (1.608–7.199)	<0.01*
CCr	0.426 (0.238–0.760)	<0.05*
nPCR	3.776 (1.940–3.747)	<0.001*
SGA scores	0.155 (0.086–0.282)	<0.001*
Transport status
(high average%)	0.198 (0.102–0.491)	<0.001*

PTH: parathyroid hormone; OR: odds ratio; Kt/V: urea clearance index; Ccr: creatinine clearance; nPCR: normalized protein catabolic rate; SGA: subjective global assessment; BPV: blood pressure variability; CI: confidence interval; OH, overhydration. *p < 0.05 was considered statistically significant.

Table 5. Multivariate linear regression of BPV associated parameters.

Parameters	β	p Value
Diabetes status	0.278	<0.01*
Phosphorus (mmol/L)	−0.070	0.83
PTH (pg/mL)	0.180	<0.05*
Kt/V	−0.720	<0.01*
CCr(ml/min)	0.299	0.26
nPCR	0.047	0.79
SGA scores	0.897	<0.01*
Transport status (high average%)	0.023	0.23

PTH: parathyroid hormone; β: standardized regression coefficient; Kt/V: urea clearance index; Ccr: creatinine clearance; nPCR: normalized protein catabolic rate; SGA: subjective global assessment; BPV: blood pressure variability; OH: overhydration. *p < 0.05 was considered statistically significant.

Data availability statement

Derived data supporting the findings of this study are available from the corresponding author [HR] on request.