Insights about serum sodium behavior after 24 hours of continuous renal replacement therapy

Romano, Thiago Gomes; Martins, Cassia Pimenta Barufi; Mendes, Pedro Vitale; Besen, Bruno Adler Maccagnan Pinheiro; Zampieri, Fernando Godinho; Park, Marcelo

doi:10.5935/0103-507X.20160026

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ORIGINAL ARTICLE • Rev. bras. ter. intensiva 28 (2) • Apr-Jun 2016 • https://doi.org/10.5935/0103-507X.20160026 copy

Insights about serum sodium behavior after 24 hours of continuous renal replacement therapy

Authorship SCIMAGO INSTITUTIONS RANKINGS

ABSTRACT

Objective:

The aim of this study was to investigate the clinical and laboratorial factors associated with serum sodium variation during continuous renal replacement therapy and to assess whether the perfect admixture formula could predict 24-hour sodium variation.

Methods:

Thirty-six continuous renal replacement therapy sessions of 33 patients, in which the affluent prescription was unchanged during the first 24 hours, were retrieved from a prospective collected database and then analyzed. A mixed linear model was performed to investigate the factors associated with large serum sodium variations (≥ 8mEq/L), and a Bland-Altman plot was generated to assess the agreement between the predicted and observed variations.

Results:

In continuous renal replacement therapy 24-hour sessions, SAPS 3 (p = 0.022) and baseline hypernatremia (p = 0.023) were statistically significant predictors of serum sodium variations ≥ 8mEq/L in univariate analysis, but only hypernatremia demonstrated an independent association (β = 0.429, p < 0.001). The perfect admixture formula for sodium prediction at 24 hours demonstrated poor agreement with the observed values.

Conclusions:

Hypernatremia at the time of continuous renal replacement therapy initiation is an important factor associated with clinically significant serum sodium variation. The use of 4% citrate or acid citrate dextrose - formula A 2.2% as anticoagulants was not associated with higher serum sodium variations. A mathematical prediction for the serum sodium concentration after 24 hours was not feasible.

Keywords:
Renal replacement therapy; Hemofiltration; Hemodiafiltration; Sodium; Critical care

	Whole group (N = 33 patients)	[Na⁺] 24 hours variation ≥ \|8\|mEq/L (N = 7 patients)	[Na⁺] 24 hours variation < \|8\|mEq/L (N = 26 patients)	*p value^ * p value of the comparison between the groups with sodium variation ≥ \|8\|mEq/L and < \|8\|mEq/L within the first 24 hours.**
Patients characteristics
Age (years)	63 (52 - 80)	58 (39 - 80)	64 (57 - 80)	0.597
SAPS 3	55 (54 - 56)	54 (42 - 55)	56 (55 - 57)	0.022
Female gender	4 (12)	1 (14)	3 (12)	0,754
Admission SOFA	8.5 [8.5 - 8.5]	8.5 [8.5 - 10.3]	8.5 [8.5 - 8.5]	0.474
Weight (kg)	68 [60 - 78]	73 [67 - 77]	68 [60 - 80]	0.343
Height (cm)	165 [164 - 171]	170 [169 - 180]	165 [163 - 170]	0.095
Pre-ICU admission LOS (days)	2.0 [1.0 - 7.0]	1.0 [0.5 - 2.5]	2.0 [1.0 - 7.8]	0.503
Diagnosis
Septic shock	25 (76)	4 (57)	21 (81)	0.320
Cardiogenic shock	4 (12)	2 (29)	2 (8)	0.190
Hypovolemic shock	1 (3)	0 (0)	1 (4)	1.000
Multiple trauma	1 (3)	1 (14)	0 (0)	0.212
Respiratory failure	1 (3)	0 (0)	1 (4)	1.000
Metabolic encephalopathy	1 (3)	0 (0)	1 (4)	1.000
Comorbidities
Chronic hypertension	21 (64)	2 (28)	19 (73)	0.071
Chronic renal failure	14 (42)	2 (28)	12 (46)	0.670
Diabetes	11 (33)	1 (14)	10 (38)	0.378
Coronary heart disease	11 (33)	2 (28)	9 (35)	1.000
Heart failure	7 (21)	1 (14)	6 (23)	1.000
COPD	3 (9)	0 (0)	3 (12)	1.000
Cirrhosis	1 (3)	1 (14)	0 (0)	0.212
ICU support^# # At any time of the intensive care unit stay. The results are expressed as the median (25% - 75%) or as the number (%).
Inotropes	16 (48)	1 (14)	15 (58)	0.085
Vasopressors	26 (79)	5 (71)	21 (81)	0.623
Mechanical ventilation	23 (70)	6 (86)	17 (65)	0.397
Antibiotics	33 (100)	7 (100)	26 (100)	1.000
Outcomes
ICU survival	21 (64)	4 (57)	17 (65)	0.686
Hospital survival	21 (64)	4 (57)	17 (65)	0.686

	Whole group (N = 36 sessions)	[Na⁺] 24 hours variation ≥ \|8\|mEq/L (N = 7 sessions)	[Na⁺] 24 hours variation < \|8\|mEq/L (N = 29 sessions)	*p value^ * p value of the comparison between the groups with sodium variation ≥\|8\|mEq/L and <\|8\|mEq/L within the first 24 hours.**
Laboratorial data
pH	7.36 [7.29 - 7.40]	7.35 [7.29 - 7.38]	7.37 [7.29 - 7.40]	0.537
PaCO₂ (mmHg)	40 [33 - 48]	36 [33 - 45]	41 [34 - 48]	0.508
HCO₃^- (mEq/L)	21 [15 - 24]	21 [19 - 22]	21 [14 - 25]	0.912
SBE (mEq/L)	-3.3 [-8.9 - -0.4]	-4.5 [-6.4 - -2.4]	-3.0 [-9.3 - -0.4]	0.842
Lactate^- (mEq/L)	2.4 [1.6 - 3.2]	2.4 [2.3 - 2.9]	2.5 [1.4 - 3.3]	0.646
Na⁺ (mEq/L)	140 [136 - 145]	151 [141 - 161]	140[136 - 144]	0.023
K⁺ (mEq/L)	4.5 [4.1 - 4.9]	4.4 [3.9 - 4.9]	4.5 [4.1 - 4.9]	0.895
Cl^- (mEq/L)	105 [101, 109]	110 [106 - 131]	103 [100 - 108]	0.074
Na⁺ - Cl^-	36.0 [32.0 - 40.0]	34.0 [32.5 - 39.0]	36.0 [32.2 - 40.0]	0.674
Na⁺ variation - during 24 hours (mEq/L)	1.0 [-2.0 - 5.0]	15.0 [10.5 - 17.0]	1.5 [0.0 - 6.5]	< 0.001
Creatinine (mg/dL)	2.62 [1.73 - 4.93]	2.62 [1.58 - 5.32]	2.62 [1.77 - 3.72]	0.929
Dysnatremia severity class
Na⁺ < 125mEq/L	0 (0)	0 (0)	0 (0)	-----
Na⁺ < 135mEq/L	6 (17)	0 (0)	6 (21)	0.301
Na⁺ ≥ 135mEq/L and ≤ 145mEq/L	19 (53)	3 (43)	16 (55)	0.422
Na⁺ > 145mEq/L	8 (22)	4 (57)	4 (14)	0.030
Na⁺ > 160mEq/L	2 (6)	2 (29)	0 (0)	0.033
CRRT prescription
CVVH	30 (84)	7 (100)	23 (79)	1.000
Post-dilutional replacement	0 (0)	0 (0)	0 (0)	-----
Pre-dilutional replacement	28 (93)	7 (100)	21 (91)	1.000
Hybrid replacement^† † In these sessions, the pre- and post-dilutional fluid replacement were used at the same time during continuous venous-venous hemofiltration and continuous venous-venous hemodiafiltration (Both sessions used the ratio pre/post dilutional = 2/1).	2 (7)	0 (0)	2 (9)	1.000
CVVHD	0 (0)	0 (0)	0 (0)	-----
CVVHDF	6 (16)	0 (0)	6 (21)	0.317
Post-dilutional replacement	0 (0)	0 (0)	0 (0)	-----
Pre-dilutional replacement	6 (100)	0 (0)	6 (100)	1.000
Hybrid replacement^† † In these sessions, the pre- and post-dilutional fluid replacement were used at the same time during continuous venous-venous hemofiltration and continuous venous-venous hemodiafiltration (Both sessions used the ratio pre/post dilutional = 2/1).	0 (0)	0 (0)	0 (0)	-----
Citrate 4% use	20 (56)	3 (43)	17 (59)	0.675
ACD-A 2.2% use	8 (22)	3 (43)	5 (17)	0.167
Heparin use	2 (6)	1 (14)	1 (3)	0.356
Lavage use	6 (16)	0 (0)	6 (79)	0.317
Dosage (mL/kg/hour)^‡ ‡ Calculated using the effluent flow rate. The results are expressed as the median (25% - 75%) or as number (%).	35 [28 - 44]	35 [27 - 43]	35 [28 - 44]	0.952
Clinical data
Cumulative fluid balance (mL)	3800 [1000 - 5400]	3800 [1050 - 5949]	3800 [1025 - 5300]	0.877
Diuresis of the day before initiation (mL)	500 [340 -1130]	690 [415 - 1420]	500 [310 - 830]	0.495

	[Na⁺] 24 hours variation	CRRT initiation	12 hours	24 hours	*p value^ * p value of the Friedman’s test, comparing the variables trough the time.**
pH	Whole group	7.37 [7.29 - 7.40]	7.34 [7.27 - 7.42]	7.40 [7.34 - 7.43]	0.072
	≥ \|8\|mEq/L	7.34 [7.32 - 7.35]	7.37 [7.31 - 7.43]	7.37 [7.31 - 7.40]	0.717
	< \|8\|mEq/L	7.37 [7.28 - 7.42]	7.34 [7.27 - 7.42]	7.40 [7.34 - 7.44]	0.132
PaCO₂ (mmHg)	Whole group	37 [30 - 47]	41 [33 - 45]	41 [37 - 46]	0.014
	≥ \|8\|mEq/L	35 [28 - 42]	37 [32 - 43]	45 [38 - 48]	0.018
	< \|8\|mEq/L	39 [31 - 47]	41 [33 - 46]	40 [37 - 45]	0.580
SBE (mEq/L)	Whole group	-3.7 [-9.0 - -1.0]	-3.4 [-7.7 - 1.1]	-0.8 [-4.4 - 1.7]	< 0.001
	≥ \|8\|mEq/L	-6.3 [-9.1 - -2.5]	-1.3 [-7.6 - 1.1]	0.6 [-1.4 - 1.2]	0.236
	< \|8\|mEq/L	-3.4 [-8.7 - -0.7]	-4.0 [-7.2 - 0.6]	-1.2 [-4.2 - 2.0]	0.095
HCO₃^- (mEq/L)	Whole group	21 [15 - 24]	22 [18 - 25]	23 [20 - 26]	< 0.001
	≥ \|8\|mEq/L	19 [14 - 23]	22 [18 - 25]	25 [22 - 27]	0.169
	< \|8\|mEq/L	21 [15 - 24]	22 [18 -25]	23 [20 - 26]	0.099
Lactate^- (mEq/L)	Whole group	2.3 [1.4 - 3.2]	2.3 [1.7 - 3.5]	2.2 [1.7 - 3.1]	0.088
	≥ \|8\|mEq/L	2.9 [2.2 - 3.7]	1.3 [0.9 - 1.8]	2.0 [1.8 - 2.2]	0.097
	< \|8\|mEq/L	2.3 [1.4 - 3.2]	2.7 [1.9 - 3.7]	2.3 [1.7 - 3.2]	0.033
K⁺ (mEq/L)	Whole group	4.5 [4.1 - 4.9]	4.3 [4.0 - 4.6]	4.2 [3.9 - 4.4]	0.164
	≥ \|8\|mEq/L	4.4 [3.7 - 5.2]	4.4 [4.2 - 4.6]	4.1 [3.9 - 4.3]	0.819
	< \|8\|mEq/L	4.5 [4.1 - 4.9]	4.3 [4.0 - 4.7]	4.2 [3.9 - 4.5]	0.227
Na⁺ - Cl^- (mEq/L)	Whole group	36.0 [32.0 - 40.0]	36.5 [34.0 - 41.0]	37.5 [32.8 - 41.2]	0.104
	≥ \|8\|mEq/L	33.3 [2.8 - 34.8]	38.5 [36.5 - 40.5]	34.0 [32.0 - 37.0]	0.074
	< \|8\|mEq/L	36.0 [33.3 - 40.0]	35.3 [34.0 - 41.0]	38.0 [34.5 - 41.5]	0.071
Temperature (ºCelsius)	Whole group	36.2 [36.7 - 36.6]	35.7 [35.2 - 36.4]	36.0 [35.6 - 36.6]	0.495
	≥ \|8\|mEq/L	36.7 [35.6 - 36.3]	35.6 [35.1 - 36.0]	36.2 [35.6 - 36.7]	0.147
	< \|8\|mEq/L	36.2 [35.6 - 36.6]	36.2 [35.5 - 36.6]	36.0 [35.6 - 36.6]	0.888
Diuresis (mL)^† † Diuresis and fluid balance are cumulative from the continuous renal replacement therapy beginning.	Whole group	0 [0 - 0]	40 [0 - 465]	191 [0 - 875]	< 0.001
	≥ \|8\|mEq/L	0 [0 - 0]	25 [0 - 463]	0^‡ ‡ p > 0.05 versus < \|8\|mEq/L group (Wilcoxon’s test). The results are expressed as the median (25% - 75%). [0 - 600]	0.180
	< \|8\|mEq/L	0 [0 - 0]	55 [0 - 420]	280 [10 - 895]	0.006
Fluid balance (mL)^† † Diuresis and fluid balance are cumulative from the continuous renal replacement therapy beginning.	Whole group	0 [0 - 0]	0 [0 - 0]	0 [-720 - 969]	0.872
	≥ \|8\|mEq/L	0 [0 - 0]	0 [0 -105]	0^‡ ‡ p > 0.05 versus < \|8\|mEq/L group (Wilcoxon’s test). The results are expressed as the median (25% - 75%). [-310 - 796]	0.446
	< \|8\|mEq/L	0 [0 - 0]	0 [0 -0]	0 [-905 - 994]	0.861

	[Na⁺] 24 hours variation	CRRT initiation	12 hours	24 hours	*p value^ * p value of the Friedman’s test, comparing the variables trough the time.**
Blood flow (mL/minute)	Whole group	180 [150 - 180]	180 [150 - 180]	180 [150 - 180]	0.651
	≥ \|8\| mEq/L	180 [158 - 180]	180 [180 - 180]	180 [150 - 180]	0.589
	< \|8\| mEq/L	180 [158 - 180]	180 [150 - 195]	180 [150 - 180]	0.958
Dialysate flow (mL/hour)	Whole group	1000 [1000 - 1200]	1000 [1000 - 1200]	1000 [1000 - 1200]	-----
	≥ \|8\| mEq/L	0 [0 - 0]	0 [0 - 0]	0 [0 - 0]	-----
	< \|8\| mEq/L	1000 [1000 - 1300]	1000 [1000 - 1300]	1000 [1000 - 1300]	-----
Replacement fluid flow (mL/hour)	Whole group	2000 [1500 - 2500]	2000 [1500 - 2500]	2500 [1500 - 2500]	-----
	≥ \|8\| mEq/L	2000 [1850 - 2000]	2000 [1850 - 2000]	2000 [1850 - 2000]	-----
	< \|8\| mEq/L	2000 [1500 - 2500]	2000 [1500 - 2500]	2000 [1500 - 2500]	-----
ACD-A 2.2% flow (mL/hour)	Whole group	180 [180 - 180]	180 [180 - 180]	180 [180 - 182]	0.223
	≥ \|8\| mEq/L	180 [180 - 180]	180 [180 - 180]	180 [180 - 180]	1.000
	< \|8\| mEq/L	180 [180 - 180]	180 [180 - 180]	180 [180 - 190]	0.368
Citrate 4% flow (mL/hour)	Whole group	150 [140 - 160]	150 [140 - 160]	150 [140 - 160]	0.692
	≥ \|8\| mEq/L	160 [145 - 170]	140 [135 - 145]	150 [140 - 160]	0.264
	< \|8\| mEq/L	150 [140 - 160]	160 [140 - 160]	150 [140 - 160]	0.973
Volume of lavage (mL/hour)	Whole group	300 [225 - 300]	300 [300 - 300]	300 [188 - 300]	0.819
	≥ \|8\| mEq/L	450 [375 - 525]	200 [150 - 250]	300 [200 - 300]	0.368
	< \|8\| mEq/L	300 [150 - 300]	300 [300 - 300]	300 [225 - 300]	0.692
Affluent fluid [Na⁺] (mEq/L)	Whole group	138 [127 - 140]	138 [127 - 140]	139 [127 - 140]	1.000
	≥ \|8\| mEq/L	140 [125 - 142]	140 [125 - 142]	140 ^† † > 0.05 versus < \|8\|mEq/L group (Wilcoxon’s test). [125 - 142]	1.000
	< \|8\| mEq/L	137 [128 - 140]	137 [128 - 140]	137 [128 - 140]	1.000
Ultrafiltration rate (mL/hour)	Whole group	100 [100 - 164]	150 [100 -2 00]	110 [100 - 164]	0.257
	≥ \|8\| mEq/L	75 [50 - 125]	150 [130 - 164]	100 [100 - 100]	0.368
	< \|8\| mEq/L	100 [100 - 164]	150 [100 - 200]	150 [100 - 200]	0.612
Effluent flow^‡ ‡ Effluent flow equalizes the sum of dialysate, replacement fluid, 2.2% ACD-A, 4% citrate, lavage and ultrafiltration rate. The results are expressed as the median (25% - 75%). (mL/hour)	Whole group	2340 [1975 - 2794]	2270 [1808 - 2745]	2290 [1800 - 2730]	0.918
	≥ \|8\|mEq/L	2225 [2010 - 3123]	2265 [1824 - 2655]	2360 [1910 - 2600]	0.895
	< \|8\|mEq/L	2385 [1925 - 2784]	2270 [1835 - 2715]	2290 [1800 - 2735]	0.964

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[1] Corresponding author: Thiago Gomes Romano, Av. Príncipe de Gales, 821, Vila Príncipe de Gales, CEP: 09060-650 - Santo André (SP), Brazil, E-mail: thromano25@hotmail.com