Acid–base balance in hemodialysis patients in everyday practice

Figures & data

Table 1. Baseline clinical characteristics and hemodialysis parameters.

Parameters	Overall (n = 75) Mean ± SD	Range	Reference values	Median
Age (years) > 65 age (%)	65.5 ± 15.8 50.7	25.8-91.4		67.17
Gender (F/M)	34/41 (45% F)
Diabetes	27 (36%)
BMI (kg/m²)	26.15 ± 6.01	12.34-44.75		24.54
CKD time > CKD stage 1 (years)	12 ± 10	1.5 month-45 years		10
Dialysis treatment time (years)	4.3 ± 10.3	1.5 month −25 years		2.17
A-V fistula/catheter	48/27 (64% fistula)
Kt/V	1.35 ± 0.18	0.66–1.67	>1.4	1.4
Hemoglobin (g/dL)	10.57 ± 1.34	6.9–14.2	10.5–11.5	10
Albumin (g/dL)	4.12 ± 0.38	3–4.9	3.5–4.5	4.2
Hemodialysis duration (hours)	4.065 ± 0.427	3–5		4.0
Bicarbonates in dialysate (mmol/L)	32.92 ± 1.78	28–36		32
UF (mL)	2017 ± 904	100–3700		2000
Qb (mL/min)	267 ± 27	200–350		250
Effective surface area (m^2)	1.511 ± 0.3078	1–2.1		1.4

Table 2. Comparison of pre-vs. post-HD acid–base parameters in two group: dialyzed via arterio-venous fistula (A-V fistula) and CVC.

	A-V fistula	CVC	p
pH pre-HD	7.371	7.307	<0.001
HCO3– pre-HD	21.98	21.64	NS
pH post-HD	7.439	7.363	<0.001
HCO3– post-HD	27.213	27.156	NS

Table 3. pH and serum bicarbonate prehemodialysis and posthemodialysis—significant correlations (UF – ultrafiltration volume, Qb – blood flow).

	pH pre- HD	HCO3^– pre- HD	pH post- HD	HCO3^– post- HD	Δ HCO3^–	Hb pre-HD	Albumin pre-HD	UF	HD duration	Qb	HCO3^– bath
pH pre-HD		0.3354 p = 0.003	0.6979 p < 0.001	NS	−0.2866 p = 0.013	NS	NS	NS	NS	NS	NS
HCO3– pre-HD	0.3354 p = 0.003		NS	0.5630 p < 0.001	−0.6448 p < 0.001	NS	NS	NS	NS	NS	NS
pH post-HD	0.6979 p < 0.001	NS		NS	NS	NS	0.3265 p = 0.004	NS	NS	NS	NS
HCO3– post-HD	NS	0.5630 p < 0.001	NS		NS	NS	0.3175 p = 0.06	NS	NS	NS	0.4892 p < 0.001
ΔHCO3–	–0.2866 p = 0.013	−0.6448 p < 0.001	NS	NS		NS	NS	NS	NS	NS	NS
HCO3– bath	NS	NS	NS	0.4892 p < 0.001	NS	NS	0.2909 p = 0.011	NS	NS	NS

Table 4. Statistically significant changes in the acid–base and urea/lactate balance during dialysis.

Parameter	Before hemodialysis	After hemodialysis	p value
pH	7.348 ± 0.057	7.412 ± 0.053	<0.001
Bicarbonates (mmol/L)	21.86 ± 2.38	27.19 ± 1.79	0.00
pCO2 (mmHg)	41.07 ± 5.78	44.02 ± 6.8	<0.001
Lactates (mmol/L)	1.71 ± 0.68	1.44 ± 0.57	<0.01
Urea (mg/dL)	128.89 ± 33.26	42.76 ± 18.01	0.00

Table 5. Comparison of pre-dialysis acid–base value in all dialysis patients depending on the used dialysate (in red color values outside the recommendation).

HCO3^– bath	Total base	No of pts	pH mean	HCO3^– mean	pH < 7.35 (pts/%)	pH 7.35–7.45 (pts)/%	pH > 7.45 (pts)	HCO3^– <20 mmol/L (pts)	HCO3^– <22 mmol/(pts)	HCO3^– >22 mmol/L (pts)	HCO3^– >26 mmol/L (pts)
28	31	2	7.355	19.15	2/100	0	0	1	1	1	0
30	33	6	7.349	20.43	3/50	3/50	0	2	3	1	0
32	35	31	7.336	22.06	18/58	12/38.7	1	3	16	15	2
33	36	5	7.366	22.16	2/40	3/60	0	1	4	0	1
34	37	11	7.336	21.4	7/63.6	4/36.4	0	3	7	4	0
35	38	18	7.379	22.63	3/16.7	15/83.3	0	1	8	10	2
36	39	2	7.267	20.6	1/50	1/50	0	2	2	0	0

Figure 1. Pre-and post-HD pH values.

Figure 2. Pre-and post-HD serum HCO₃^–.

Table 6. Comparison of postdialysis acid–base value in all dialysis patients depending on the used dialysate (in red color values outside the norm).

HCO3^– bath	Total base	No of pts	pH mean	HCO3^– mean	pH < 7.35 (pts)/%	pH 7.35–7.45 (pts)/%	pH > 7.45 (pts)/%	HCO3^– <26 mmol/L (pts)	HCO3^– 26–28 mmol/(pts)	HCO3^– 28–30 mmol/L (pts)	HCO3^– >30 mmol/L (pts)
28	31	2	7.427	23.75	1/50	1/50	0	0	0	1	1
30	33	6	7.421	25.98	1/16.7	3/50	2/33.3	2	3	1	0
32	35	31	7.393	26.95	6/19.4	21/67.7	4/12.9	5	19	6	1
33	36	5	7.418	26.34	1/20	2/40	2/40	2	3	0	0
34	37	11	7.412	27.69	2/18.2	6/54.5	3/27.3	0	6	5	0
35	38	18	7.446	28.04	0	9/50	9/50	1	8	9	0
36	39	2	7.326	29.8	0	1/50	1/50	2	0	0	0