Hypotonic versus isotonic maintenance fluids in critically ill children: a multicenter prospective randomized study

Efficacy and safety of isotonic versus hypotonic intravenous maintenance fluids in hospitalized children: an updated systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Iatrogenic hyponatremia is a common complication following intravenous maintenance fluid therapy (IV-MFT) in hospitalized children. Despite the American Academy of Pediatrics' 2018 recommendations, IV-MFT prescribing practices still vary considerably.

OBJECTIVES

This meta-analysis aimed to compare the safety and efficacy of isotonic versus hypotonic IV-MFT in hospitalized children.

DATA SOURCES

We searched PubMed, Scopus, Web of Science, and Cochrane Central from inception to October 1, 2022.

STUDY ELIGIBILITY CRITERIA

We included randomized controlled trials (RCTs) comparing isotonic versus hypotonic IV-MFT in hospitalized children, either with medical or surgical conditions. Our primary outcome was hyponatremia following IV-MFT. Secondary outcomes included hypernatremia, serum sodium, serum potassium, serum osmolarity, blood pH, blood sugar, serum creatinine, serum chloride, urinary sodium, length of hospital stay, and adverse outcomes.

STUDY APPRAISAL AND SYNTHESIS METHODS

Random-effects models were used to pool the extracted data. We performed our analysis based on the duration of fluid administration (i.e., ≤ 24 and > 24 h). The Grades of Recommendations Assessment Development and Evaluation (GRADE) scale was used to evaluate the strength and level of evidence for recommendations.

RESULTS

A total of 33 RCTs, comprising 5049 patients were included. Isotonic IV-MFT significantly reduced the risk of mild hyponatremia at both ≤ 24 h (RR = 0.38, 95% CI [0.30, 0.48], P < 0.00001; high quality of evidence) and > 24 h (RR = 0.47, 95% CI [0.37, 0.62], P < 0.00001; high quality of evidence). This protective effect of isotonic fluid was maintained in most examined subgroups. Isotonic IV-MFT significantly increased the risk of hypernatremia in neonates (RR = 3.74, 95% CI [1.42, 9.85], P = 0.008). In addition, it significantly increased serum creatinine at ≤ 24 h (MD = 0.89, 95% CI [0.84, 0.94], P < 0.00001) and decreased blood pH (MD = -0.05, 95% CI [-0.08 to -0.02], P = 0.0006). Mean serum sodium, serum osmolarity, and serum chloride were lower in the hypotonic group at ≤ 24 h. The two fluids were comparable in terms of serum potassium, length of hospital stay, blood sugar, and the risk of adverse outcomes.

LIMITATIONS

The main limitation of our study was the heterogeneity of the included studies.

CONCLUSIONS AND IMPLICATIONS OF KEY FINDINGS

Isotonic IV-MFT was superior to the hypotonic one in reducing the risk of iatrogenic hyponatremia in hospitalized children. However, it increases the risk of hypernatremia in neonates and may lead to renal dysfunction. Given that the risk of hypernatremia is not important even in the neonates, we propose to use balanced isotonic IV-MFT in hospitalized children as it is better tolerated by the kidneys than 0.9% saline.

SYSTEMATIC REVIEW REGISTRATION NUMBER

CRD42022372359. Graphical abstract A higher resolution version of the Graphical abstract is available as Supplementary information.

ESPNIC clinical practice guidelines: intravenous maintenance fluid therapy in acute and critically ill children- a systematic review and meta-analysis

PURPOSE

Intravenous maintenance fluid therapy (IV-MFT) prescribing in acute and critically ill children is very variable among pediatric health care professionals. In order to provide up to date IV-MFT guidelines, the European Society of Pediatric and Neonatal Intensive Care (ESPNIC) undertook a systematic review to answer the following five main questions about IV-MFT: (i) the indications for use (ii) the role of isotonic fluid (iii) the role of balanced solutions (iv) IV fluid composition (calcium, magnesium, potassium, glucose and micronutrients) and v) and the optimal amount of fluid.

METHODS

A multidisciplinary expert group within ESPNIC conducted this systematic review using the Scottish Intercollegiate Guidelines Network (SIGN) grading method. Five databases were searched for studies that answered these questions, in acute and critically children (from 37 weeks gestational age to 18 years), published until November 2020. The quality of evidence and risk of bias were assessed, and meta-analyses were undertaken when appropriate. A series of recommendations was derived and voted on by the expert group to achieve consensus through two voting rounds.

RESULTS

56 papers met the inclusion criteria, and 16 recommendations were produced. Outcome reporting was inconsistent among studies. Recommendations generated were based on a heterogeneous level of evidence, but consensus within the expert group was high. "Strong consensus" was reached for 11/16 (69%) and "consensus" for 5/16 (31%) of the recommendations.

CONCLUSIONS

Key recommendations are to use isotonic balanced solutions providing glucose to restrict IV-MFT infusion volumes in most hospitalized children and to regularly monitor plasma electrolyte levels, serum glucose and fluid balance.

Korean Society of Nephrology 2022 recommendations on controversial issues in diagnosis and management of hyponatremia

The Korean Society for Electrolyte and Blood Pressure Research, in collaboration with the Korean Society of Nephrology, has published a clinical practice guideline (CPG) document for hyponatremia treatment. The document is based on an extensive evidence-based review of the diagnosis, evaluation, and treatment of hyponatremia with the multidisciplinary participation of representative experts in hyponatremia with methodologist support for guideline development. This CPG consists of 12 recommendations (two for diagnosis, eight for treatment, and two for special situations) based on eight detailed topics and nine key questions. Each recommendation begins with statements graded by the strength of the recommendations and the quality of the evidence. Each statement is followed by rationale supporting the recommendations. The committee issued conditional recommendations in favor of rapid intermittent bolus administration of hypertonic saline in severe hyponatremia, the use of vasopressin receptor antagonists in heart failure with hypervolemic hyponatremia, and syndrome of inappropriate antidiuresis with moderate to severe hyponatremia, the individualization of desmopressin use, and strong recommendation on the administration of isotonic fluids as maintenance fluid therapy in hospitalized pediatric patients. We hope that this CPG will provide useful recommendations in practice, with the aim of providing clinical support for shared decision-making to improve patient outcomes.

Balanced Crystalloids versus Normal Saline in Children with Critical Asthma

There is little known about the impact of maintenance fluid choice in children with critical asthma on clinical outcomes. Our primary study objectives were to determine the differences in the serum chloride and bicarbonate levels based on the receipt of 0.9% saline or a balanced solution. The secondary study objectives included differences in acute kidney injury (AKI) and intensive care unit (ICU)/hospital length of stay (LOS). In this retrospective cohort study, we included 1166 patients admitted to a quaternary children's hospital with critical asthma between 2017 and 2019. The patients were stratified based on if they received 0.9% saline or a balanced solution (Lactated Ringer's or Plasma-lyte) for maintenance therapy. The study outcomes were determined using independent sample t-tests, multivariable logistic regression, and negative binomial regression. The patients who received 0.9% saline maintenance therapy had a significantly higher increase in their serum chloride levels when compared to those who received balanced solutions (0.9% saline: +4 mMol/L, balanced: +2 mMol/L, p = 0.002). There was no difference in the decrease in the serum bicarbonate levels (0.9% saline: -0.4 mMol/L, balanced: -0.5 mMol/L, p = 0.830). After controlling for age, race, sex, and the Pediatric Logistic Organ Dysfunction (PELOD-2) score, there was no association between the type of fluid received and the development of AKI (OR 0.87, 95% CI: 0.46-1.63, p = 0.678). Additionally, there was no association between the type of fluid and hospital or ICU LOS. Thus, despite higher serum chloride levels in the patients that received 0.9% saline, the choice of fluid therapy did not have an impact on the serum bicarbonate values, the development of AKI or hospital and ICU LOS, suggesting there is little difference between 0.9% saline and balanced solutions as maintenance therapy in children with critical asthma.

Korean Society of Nephrology 2022 Recommendations on controversial issues in diagnosis and management of hyponatremia

The Korean Society for Electrolyte and Blood Pressure Research, in collaboration with the Korean Society of Nephrology, has published a clinical practice guideline (CPG) document for hyponatremia treatment. The document is based on an extensive evidence-based review of the diagnosis, evaluation, and treatment of hyponatremia with the multidisciplinary participation of representative experts in hyponatremia with methodologist support for guideline development. This CPG consists of 12 recommendations (two for diagnosis, eight for treatment, and two for special situations) based on eight detailed topics and nine key questions. Each recommendation begins with statements graded by the strength of the recommendations and the quality of the evidence. Each statement is followed by rationale supporting the recommendations. The committee issued conditional recommendations in favor of rapid intermittent bolus administration of hypertonic saline in severe hyponatremia, the use of vasopressin receptor antagonists in heart failure with hypervolemic hyponatremia, and syndrome of inappropriate antidiuresis with moderate to severe hyponatremia, the individualization of desmopressin use, and strong recommendation on the administration of isotonic fluids as maintenance fluid therapy in hospitalized pediatric patients. We hope that this CPG will provide useful recommendations in practice, with the aim of providing clinical support for shared decision-making to improve patient outcomes.

Risk of Electrolyte Disorders in Acutely Ill Children Receiving Commercially Available Plasmalike Isotonic Fluids: A Randomized Clinical Trial

IMPORTANCE

The use of isotonic fluid therapy is currently recommended in children, but there is limited evidence of optimal fluid therapy in acutely ill children.

OBJECTIVE

To evaluate the risk for electrolyte disorders, including hyponatremia, hypernatremia, and hypokalemia, and the risk of fluid retention in acutely ill children receiving commercially available plasmalike isotonic fluid therapy.

DESIGN, SETTING, AND PARTICIPANTS

This unblinded, randomized clinical pragmatic trial was conducted at the pediatric emergency department of Oulu University Hospital, Finland, from October 3, 2016, through April 15, 2019. Eligible study subjects (N = 614) were between 6 months and 12 years of age, required hospitalization due to an acute illness, and needed intravenous fluid therapy. Exclusion criteria included a plasma sodium concentration of less than 130 mmol/L or greater than 150 mmol/L on admission; a plasma potassium concentration of less than 3.0 mmol/L on admission; clinical need of fluid therapy with 10% glucose solution; a history of diabetes, diabetic ketoacidosis, or diabetes insipidus; a need for renal replacement therapy; severe liver disease; pediatric cancer requiring protocol-determined chemotherapy hydration; and inborn errors of metabolism. All outcomes and samples size were prespecified except those clearly marked as exploratory post hoc analyses. All analyses were intention to treat.

INTERVENTIONS

Acutely ill children were randomized to receive commercially available plasmalike isotonic fluid therapy (140 mmol/L of sodium and 5 mmol/L potassium in 5% dextrose) or moderately hypotonic fluid therapy (80 mmol/L sodium and 20 mmol/L potassium in 5% dextrose).

MAIN OUTCOMES AND MEASURES

The primary outcome was the proportion of children with any clinically significant electrolyte disorder, defined as hypokalemia less than 3.5 mmol/L, hypernatremia greater than 148 mmol/L, or hyponatremia less than 132 mmol/L during hospitalization due to acute illness. The main secondary outcomes were the proportion of children with severe hypokalemia and weight change.

RESULTS

There were 614 total study subjects (mean [SD] age, 4.0 [3.1] years; 315 children were boys [51%] and all 614 were Finnish speaking [100%]). Clinically significant electrolyte disorder was more common in children receiving plasmalike isotonic fluid therapy (61 of 308 patients [20%]) compared with those receiving moderately hypotonic fluid therapy (9 of 306 patients [2.9%]; 95% CI of the difference, 12%-22%; P < .001). The risk of developing electrolyte disorder was 6.7-fold greater in children receiving isotonic fluid therapy. Hypokalemia developed in 57 patients (19%) and hypernatremia developed in 4 patients (1.3%) receiving plasmalike isotonic fluid therapy. Weight change was greater in children receiving isotonic, plasmalike fluid therapy compared with those receiving mildly hypotonic fluids (mean weight gain, 279 vs 195 g; 95% CI, 16-154 g; P = .02).

CONCLUSIONS AND RELEVANCE

In this randomized clinical trial, commercially available plasmalike isotonic fluid therapy markedly increased the risk for clinically significant electrolyte disorders, mostly due to hypokalemia, in acutely ill children compared with previously widely used moderately hypotonic fluid therapy containing 20 mmol/L of potassium.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT02926989.

Association Between Hyponatremia and Maintenance Intravenous Solutions in Critically Ill Children: A Retrospective Observational Study

Objetive: We sought to determine the association between maintenance intravenous solutions and the presence of hyponatremia in children in pediatric intensive care (PICU). Materials and Methods: An analytical observational study in children hospitalized in the PICU between January 2015 and December 2018. Patients who received maintenance fluids within the first 48 h after admission and who had at least two serum sodium levels drawn during this time were included. Measurements and Main Results: A total of 1,668 patients were admitted to the PICU during the study period, 503 of whom met the inclusion criteria. The median age was 24 months (IQR 8-96) and 50.9% were female. Altogether, 24.1% of the children developed hyponatremia; it was more frequent in those who received hypotonic solutions (63 vs. 37%; OR 1.41 95% CI 0.92, 2.15 p = 0.106), who also had a longer hospital stay (20 vs. 14 days, difference in means 8 days, 95% CI 2.67, 13.3, p = 0.001). Children who received loop diuretics and those who were post-operative had a greater risk of developing hyponatremia if they received hypotonic solutions (aOR 2.1 95% CI 1.41, 3.0, p = 0.000). Those with balanced isotonic solutions had a lower risk of developing hyponatremia (aOR 0.59 95% CI 0.35, 0.99, p = 0.004) and hyperchloremia (aOR 0.51 95% CI 0.34, 0.77, p = 0.000), adjusted for disease severity. A greater risk of death was found in the group with severe hyponatremia <130 mEq/L (aOR 9.75 95% CI 1.64-58.15; p = 0.01). Conclusions: Hyponatremia associated with the use of hypotonic maintenance solutions occurs in one out of four children in intensive care. The use of these solutions is associated with a longer hospital stay, and the main risk groups are post-operative patients and those who receive loop diuretics. Clinical studies are needed to determine which maintenance solutions have the greatest efficacy and safety in critically ill children.

Risks of severe hyponatremia in children receiving hypotonic fluids

Intravenous fluids are frequently used in hospitalized children. Hypotonic fluids have been the standard of care in pediatrics for many years. This might be explained by the empiricism of early recommendations favoring fluids with dextrose, but an insufficient amount of sodium. The risk of hyponatremia (<135mmol/L) might be increased by the occurrence of the syndrome of inappropriate secretion of antidiuretic hormone (SIADH) in the course of common acute diseases (e.g., bronchiolitis, acute gastroenteritis, encephalitis, meningitis) in children. Severe hyponatremia (<130mmol/L) is often associated with neurologic complications leading to sequelae or even death. Over the last few years, hyponatremia induced by hypotonic fluids has been increasingly reported, and significant progress has been made in the understanding of cerebral edema and osmotic demyelination. Several randomized clinical trials have shown weak but significant evidence that isotonic fluids were superior to hypotonic solutions in preventing hyponatremia. However, clinical practices have not changed much in France, as suggested by the analysis of intravenous fluids ordered from the Assistance Publique-Hôpitaux de Paris (AP-HP) central pharmacy (PCH) in 2017. Therefore, it would be advisable that national guidelines be released under the French Health Authorities regarding the safe infusion of infants and children.

Isotonic versus hypotonic saline as maintenance intravenous fluid therapy in children under 5 years of age admitted to general paediatric wards: a randomised controlled trial

Background: To prevent the risk of iatrogenic hyponatraemia in hospitalised children, isotonic fluid has been recommended as maintenance intravenous fluid (IVF). There are few studies which compare half normal saline with normal saline as maintenance IVF in general paediatric wards.Aim: To compare the safety and efficacy of half normal saline with normal saline as maintenance IVF in general paediatric wards.Methods: Children aged between 3 months and 5 years with an anticipated requirement for IVF for 24 h were randomised to receive either half normal saline (0.45% saline in 5% dextrose) or normal saline (0.9% saline in 5% dextrose). The primary objective was to compare the incidence of hyponatraemia (serum sodium <135 mmol/L with a decrease from baseline of at least 4 mmol/L) at 24 h in children receiving half normal saline with those receiving normal saline. Secondary objectives were to compare the incidence of moderate (sodium <130 mmol/L), severe (sodium <125 mmol/L) and symptomatic hyponatraemia, change in serum sodium level from baseline and the incidence of hypernatraemia.Results: A total of 168 children were randomised to receive either normal saline (n = 84) or half normal saline (n = 84). More than two-thirds of the children were suffering from respiratory diseases (pneumonia and bronchiolitis) and diseases of the nervous system (meningoencephalitis, febrile seizures and epilepsy). The incidence of hyponatraemia at 12 h in children receiving half normal saline was similar to that in those receiving normal saline (6 vs 4.8%; Relative risk (RR) 1.2; 95% CI 0.3.0-4.8; p = 0.73). Although the incidence of hyponatraemia at 24 h in children receiving half normal saline was higher than in those receiving normal saline, the difference was not statistically significant (14.3 vs 6%; RR 2.6; 95% CI 0.9-7.8; p = 0.07). One child in the isotonic group and one in the hypotonic group developed moderate and severe hyponatraemia, respectively. There was no significant difference in the incidence of hypernatraemia between two groups (RR 0.7; 95% CI 0.16-3.3).Conclusion: Half-normal saline as maintenance IVF does not result in a significantly increased risk of hyponatraemia in general paediatric ward patients under 5 years of age.

Isotonic versus Hypotonic Intravenous Maintenance Fluids in Children: A Randomized Controlled Trial

OBJECTIVE

To compare the incidence of hyponatremia during the first 48 h in hospitalized children receiving normal saline vs. N/2 saline as maintenance intravenous fluid.

METHODS

This open label, randomized controlled trial to compare the incidence of hyponatremia in hospitalized children receiving normal saline (0.9% sodium chloride in 5% dextrose) vs. N/2 saline (0.45% sodium chloride in 5% dextrose) as maintenance fluid was conducted from December 2014 through November 2015 in a tertiary care teaching hospital. Children between 1 mo and 18 y requiring maintenance intravenous fluids were randomized to receive normal saline with 5% dextrose (n = 75) or N/2 saline with 5% dextrose (n = 75).

RESULTS

Both groups were comparable for demographic variables and illness severity at baseline. Incidence of hyponatremia at 24 h of hospitalization was comparable between normal saline and N/2 saline group, 3(4%) vs. 6(8%) cases, respectively; p value 0.494. Mean serum sodium levels were marginally higher in normal saline group (138.3 ± 6.0 mEq/L) as compared with N/2 saline group (135.1 ± 4.4 mEq/L) (p value <0.01) at 24 h of hospitalization. Incidence of hyponatremia at 48 h and hypernatremia at 24 and 48 h was comparable in two groups.

CONCLUSIONS

The use of either N/2 saline or normal saline in sick children at standard maintenance fluid rates is associated with low but comparable incidence of hypo or hypernatremia in first 24 h of hospitalization. Both types of fluids appear acceptable in hospitalized sick children.

Hyponatraemia in a Lao paediatric intensive care unit: Prevalence, associations and intravenous fluid use

AIM

Hyponatraemia is a common and potentially deadly complication affecting hospitalised children world-wide. Hypotonic intravenous fluids can be a significant exacerbating factor. Exclusive use of isotonic fluids, coupled with rigorous blood monitoring, has proven effective in reducing hyponatraemia in developed settings. In developing countries, where hyponatraemia is often more common and severe, different factors may contribute to its incidence and detection. We aimed to determine the prevalence and disease associations of hyponatraemia and describe the intravenous maintenance fluid prescribing practices in a Lao paediatric intensive care unit.

METHODS

We conducted a cross-sectional study of 164 children aged 1 month to 15 years admitted to intensive care at a tertiary centre in Lao People's Democratic Republic (PDR) and recorded their serum sodium and clinical data at admission and on two subsequent days.

RESULTS

Hyponatraemia was detected in 41% (67/164, confidence interval 34-48%) of children, the majority of which was mild (34%, 56/164) and present at admission (35%, 55/158). Hyponatraemia was more common in malnourished children (odds ratio (OR) 2.3, P = 0.012) and females (OR 1.9, P = 0.045). Hyponatraemia correlated with death or expected death after discharge (OR 2.2, P = 0.015); 88% received maintenance intravenous fluids, with 67% of those receiving a hypotonic solution. Electrolyte testing was only performed in 20% (9/46) of patients outside the study protocol.

CONCLUSIONS

Hyponatraemia is highly prevalent in critically ill children in Lao PDR, as is the continued use of hypotonic intravenous fluids. With financial and practical barriers to safely detecting and monitoring electrolyte disorders in this setting, this local audit can help promote testing and has already encouraged changes to fluid prescribing.

Hypotonic versus isotonic maintenance fluid administration in the pediatric surgical patient. Semin Pediatr Surg 2019;28:43-46. [PMID: 30824133 DOI: 10.1053/j.sempedsurg.2019.01.007]

Intravenous fluid administration has been occurring for well over one hundred years for a variety of pediatric disease processes. Surprisingly, clinicians have yet to agree upon a standardized intravenous solution. There is ongoing debate regarding the administration of isotonic versus hypotonic fluids as maintenance solutions. In this article, we will review what is known about different maintenance solutions, discuss the potential complications with their use, and summarize the available evidence to help guide clinicians in their choice of maintenance fluids for their patients.

Syndrome of Inappropriate Antidiuresis

The syndrome of inappropriate antidiuresis (SIAD) is a common cause of hyponatremia in hospitalized children. SIAD refers to euvolemic hyponatremia due to nonphysiologic stimuli for arginine vasopressin production in the absence of renal or endocrine dysfunction. SIAD can be broadly classified as a result of tumors, pulmonary or central nervous system disorders, medications, or other causes such as infection, inflammation, and the postoperative state. The presence of hypouricemia with an elevated fractional excretion of urate can aid in the diagnosis. Treatment options include fluid restriction, intravenous saline solutions, oral sodium supplements, loop diuretics, oral urea, and vasopressin receptor antagonists (vaptans).

Clinical Practice Guideline: Maintenance Intravenous Fluids in Children

Maintenance intravenous fluids (IVFs) are used to provide critical supportive care for children who are acutely ill. IVFs are required if sufficient fluids cannot be provided by using enteral administration for reasons such as gastrointestinal illness, respiratory compromise, neurologic impairment, a perioperative state, or being moribund from an acute or chronic illness. Despite the common use of maintenance IVFs, there is high variability in fluid prescribing practices and a lack of guidelines for fluid composition administration and electrolyte monitoring. The administration of hypotonic IVFs has been the standard in pediatrics. Concerns have been raised that this approach results in a high incidence of hyponatremia and that isotonic IVFs could prevent the development of hyponatremia. Our goal in this guideline is to provide an evidence-based approach for choosing the tonicity of maintenance IVFs in most patients from 28 days to 18 years of age who require maintenance IVFs. This guideline applies to children in surgical (postoperative) and medical acute-care settings, including critical care and the general inpatient ward. Patients with neurosurgical disorders, congenital or acquired cardiac disease, hepatic disease, cancer, renal dysfunction, diabetes insipidus, voluminous watery diarrhea, or severe burns; neonates who are younger than 28 days old or in the NICU; and adolescents older than 18 years old are excluded. We specifically address the tonicity of maintenance IVFs in children.The Key Action Statement of the subcommittee is as follows:1A: The American Academy of Pediatrics recommends that patients 28 days to 18 years of age requiring maintenance IVFs should receive isotonic solutions with appropriate potassium chloride and dextrose because they significantly decrease the risk of developing hyponatremia (evidence quality: A; recommendation strength: strong).

Hospital-Acquired Hyponatremia in Children Following Hypotonic versus Isotonic Intravenous Fluids Infusion

Hypotonic solutions have been used in pediatrics for maintenance of intravenous (IV) hydration. However, recent randomized control trials and cohort studies have raised significant concerns for association with hospital-acquired hyponatremia (HAH). The study aimed to assess whether the use of hypotonic parenteral solutions (PS) compared with isotonic PS is associated with increased HAH risk in children with common pediatric conditions. Retrospective chart review of 472 patients aged 2 months to 18 years who received either isotonic or hypotonic PS as maintenance fluids. Administration of hypotonic PS was associated with a four-fold increase in risk of developing HAH in the univariate analysis, (unadjusted odds ratio (OR) = 3.99; 95% confidence interval (CI): 1.36–11.69, p = 0.01). Hypotonic PS were associated with HAH (p = 0.04) when adjusted for the level of admission serum CO₂. There was a mean decrease of serum sodium of 0.53 mEq/L in the hypotonic group compared to the mean increase of 4.88 mEq/L in the isotonic group. These data suggest that hypotonic PS are associated with HAH in children admitted for common pediatric conditions. Isotonic PS should be considered as a safer choice for maintenance fluid hydration.

In children requiring intravenous fluid for hydration maintenance, which out of hypotonic saline and isotonic saline is less likely to result in the development of hyponatraemia?

The administration of intravenous fluids remains a common intervention for hospitalised children. Commonly used hypotonic fluids administered at maintenance rates provide 2-4 mmol/kg/day of sodium. Being hypotonic, the development of hyponatraemia remains a risk. The consequences of hyponatraemia are not insignificant, with possibilities of irreversible neurological morbidity and mortality. There is currently no clear consensus on the optimal composition of fluids to be used for intravenous rehydration. A review of the available literature suggests that children who receive isotonic fluid have a lower risk of developing hyponatraemia, regardless of the rate of administration. This result is most applicable in the first 24 h of administration in a wide age group of paediatric patients with varying severities of illness.

Hospital-acquired Hyponatremia in Pediatric Intensive Care Unit

Objective:

The objective of the study was to evaluate the etiology of hospital-acquired hyponatremia (HAH) and its effects on morbidity and mortality in the Pediatric Intensive Care Unit (PICU) patients.

Design:

This study design was a prospective observational case–control study.

Setting:

this study was conducted at tertiary care PICU.

Materials and Methods:

All consecutive cases admitted with at least one measured serum sodium (P_Na) value were evaluated. Those with normal admission P_Na were followed till they develop hyponatremia (P_Na < 35 mEq/L) 7 days or PICU discharge whichever was earlier.

Results:

During the study period, 123 (19.6%) cases developed HAH and 126 patients remained isonatremic (control group). The admission P_Na 138.8 ± 3.03 mEq/L decreased to 132 ± 2.58 mEq/L (drop of 6.68 ± 3.39 mEq/L, P < 0.001) in HAH cases. The use of antidiuretic hormone (ADH)-stimulating drugs (odds ratio [OR]: 2.83, P = 0.01), postsurgical status (OR: 2.95, P = 0.006), and fluid intake ml/kg (OR: 1.0, P = 0.001) were found to be significant risk factors in HAH group on multivariate analysis. HAH cases had prolonged PICU stay (P = 0.000) and mechanical ventilation (P = 0.01), but no difference in the mortality when compared to controls.

Conclusions:

HAH is associated with increased fluid intake, presence of ADH-stimulating drugs or conditions, and postsurgical status and has an adverse effect on the outcome of PICU patients.

Intravenous isotonic fluids induced a positive trend in natraemia in children admitted to a general paediatric ward

AIM

Using hypotonic intravenous solutions for baseline fluid needs in paediatric patients on a nil by mouth diet may cause serious complications, including hyponatraemia, cerebral oedema and even death. We analysed the evolution of natraemia and explored any adverse effects on children treated with intravenous isotonic fluids.

METHODS

This was a prospective study of 50 patients consecutively admitted to a general paediatric ward who were treated with isotonic intravenous fluids and on a nil by mouth diet.

RESULTS

The most prevalent diagnosis was acute gastroenteritis (64%). Hyponatraemia, defined as sodium in plasma of <135 mEq/L, affected 22% of the subjects, but none displayed this during the first postadmission analysis at a median of eight hours. Sodium levels changed by an average of +0.64 mEq/L/hour. The subgroup analysis (0.91 versus 0.56 mEq/L/hour, p = 0.02) and multiple linear regression (R(2) = 0.756) showed a greater increase in sodium when patients had hyponatraemia on admission. Iatrogenic hyponatraemia was not detected, but two patients showed mild hypernatraemia and 35% developed clinically insignificant hyperchloraemia.

CONCLUSION

Using intravenous isotonic fluids induced a positive trend in natraemia on a general paediatric ward, particularly if patients were hyponatraemic when admitted, and did not induce clinically relevant adverse effects.

Perioperative fluid management and postoperative hyponatremia in children

Intravenous (IV) fluids are used ubiquitously when children undergo surgical procedures. Until recently, Holliday and Segar's guidelines for calculating maintenance fluids dictated fluid management strategies in postoperative pediatric patients. An increased recognition of hospital-acquired hyponatremia and its associated morbidity has led to a critical re-examination of IV fluid management in this population. Postsurgical patients are at high risk of developing hyponatremia due to the presence of non-osmotic stimuli for antidiuretic hormone release. Recent studies have established that, as they are administered in current practice, hypotonic maintenance fluids are associated with increased rates of hyponatremia. The best available data demonstrate that administration of isotonic fluid reduces hyponatremic risk. In this review, we discuss the collective data available on the subject and offer guidelines for fluid management and therapeutic monitoring.

Isotonic versus Hypotonic Parenteral Maintenance Fluids in Very Severe Pneumonia

OBJECTIVE

To compare the risk of hyponatremia between hypotonic and isotonic parenteral maintenance solutions (PMS) administered to children with very severe pneumonia, admitted in the general pediatric ward.

METHODS

A randomized controlled open label trial was conducted in the pediatrics department of a tertiary care medical college hospital including euvolemic children 2 mo to 5 y of age, fulfilling the WHO clinical definition of very severe pneumonia and requiring PMS. They were randomized to receive either isotonic PMS (0.9% saline in 5% dextrose and potassium chloride 20 meq/L) or hypotonic PMS (0.18% saline in 5% dextrose and potassium chloride 20 meq/L) at standard rates for next 24 h.

RESULTS

A total of 119 children were randomized (59: Isotonic; 60: Hypototonic PMS). Nine (15%) children in the isotonic PMS group and 29 (48%) in the hypotonic PMS group developed hyponatremia during the study period, (p <0.001) with a relative risk being 3.16 (95% CI 1.64 to 6.09). Mean serum sodium was significantly lower in the hypotonic group compared to the isotonic group (p < 0.001 each at 6, 12 and 24 h). The difference in mean change in serum sodium from baseline was also significant at 12 and 24 h (5.4 and 5.8 meq/L respectively; p < 0.001 each).

CONCLUSIONS

This study demonstrates the rationality of the use of isotonic PMS in children with respiratory infections, a condition regularly encountered by most pediatricians.

Use of Hypotonic Maintenance Intravenous Fluids and Hospital-Acquired Hyponatremia Remain Common in Children Admitted to a General Pediatric Ward

AIM

To evaluate maintenance intravenous fluid-prescribing practices and the incidence of hospital-acquired hyponatremia in children admitted to a general pediatric ward.

METHODS

This is a prospective observational study conducted over a 2-month period in children ages 2 months to 5 years who were admitted to a general pediatric ward and who were receiving maintenance intravenous fluids. The composition, rate, and duration of intravenous fluids were chosen at the discretion of the treating physician. Serum biochemistries were obtained at baseline and 24 h following admission. Patients who were at high risk for developing hyponatremia or hypernatremia or had underlying chronic diseases or were receiving medications associated with a disorder in sodium and water homeostasis were excluded. Intravenous fluid composition and the incidence of hyponatremia (sodium <135 mEq/L) were assessed.

RESULTS

Fifty-six children were enrolled. All received hypotonic fluids; 87.5% received 0.18% sodium chloride (NaCl) and 14.3% received 0.45% NaCl. Forty percent of patients (17/42) with a serum sodium (SNa) less than 140 mEq/L experienced a fall in SNa with 12.5% of all patients (7/56) developing hospital-acquired or aggravated hyponatremia (126-134 mEq/L) with fall in SNa between 2 and 10 mEq/L.

CONCLUSION

Administration of hypotonic fluids was a prevalent practice in children admitted to a general pediatric ward and is associated with acute hospital-acquired hyponatremia.

The effect of NaCl 0.9% and NaCl 0.45% on sodium, chloride, and acid-base balance in a PICU population

OBJECTIVES

To study the effect of two intravenous maintenance fluids on plasma sodium (Na), and acid-base balance in pediatric intensive care patients during the first 24h of hospitalization.

METHODS

A prospective randomized controlled study was performed, which allocated 233 patients to groups: (A) NaCl 0.9% or (B) NaCl 0.45%. Patients were aged 1 day to 18 years, had normal electrolyte concentrations, and suffered an acute insult (medical/surgical).

MAIN OUTCOME MEASURED

change in plasma sodium. Parametric tests: t-tests, ANOVA, X(2) statistical significance level was set at α=0.05.

RESULTS

Group A (n=130): serum Na increased by 2.91 (±3.9)mmol/L at 24h (p<0.01); 2% patients had Na higher than 150 mmol/L. Mean urinary Na: 106.6 (±56.8)mmol/L. No change in pH at 0 and 24h. Group B (n=103): serum Na did not display statistically significant changes. Fifteen percent of the patients had Na<135 mmol/L at 24h. The two fluids had different effects on respiratory and post-operative situations.

CONCLUSIONS

The use of saline 0.9% was associated with a lower incidence of electrolyte disturbances.

Isotonic versus hypotonic saline solution for maintenance intravenous fluid therapy in children: a systematic review

BACKGROUND

The administration of hypotonic saline solution for maintenance intravenous fluid (IVF) therapy has been the standard of care, but recent evidence has shown this treatment to be associated with hyponatremia-related complications. The aim of this systematic review was to determine which IVF, i.e., a hypotonic or an isotonic saline solution, poses less risk for the development of hyponatremia among hospitalized children who require maintenance IVF therapy.

METHODS

Medline, Cochrane Library, LILACS, Current Controlled Trials, reference lists, and abstract proceedings were searched for randomized controlled trials (RCTs) comparing hypotonic and isotonic saline solutions for maintenance IVF therapy in hospitalized children. Two reviewers independently assessed all potentially relevant studies and subsequently extracted data and evaluated the methodological quality of the RCTs. Studies were then combined and analyzed using a random effects model.

RESULTS

Eleven RCTs met the inclusion criteria. Our analysis of these 11 RCTs showed that among hospitalized children receiving maintenance IVF therapy, isotonic solutions significantly decreased the risk of developing hyponatremia [relative risk (RR) 0.50, 95% confidence interval (CI) 0.40-0.62] without significantly increasing the risk for hypernatremia (RR 0.83, 95% CI 0.41-1.67).

CONCLUSIONS

Current evidence does not support the standard practice of prescribing a hypotonic saline solution as maintenance IVF therapy to hospitalized children. Although there is no single IVF composition ideal for all children, an isotonic saline solution does appear to be the safer choice when maintenance IVF therapy is used in the general pediatric population.

140 mmol/L of sodium versus 77 mmol/L of sodium in maintenance intravenous fluid therapy for children in hospital (PIMS): a randomised controlled double-blind trial

BACKGROUND

Use of hypotonic intravenous fluid to maintain hydration in children in hospital has been associated with hyponatraemia, leading to neurological morbidity and mortality. We aimed to assess whether use of fluid solutions with a higher sodium concentration reduced the risk of hyponatraemia compared with use of hypotonic solutions.

METHODS

We did a randomised controlled double-blind trial of children admitted to The Royal Children's Hospital (Melbourne, VIC, Australia) who needed intravenous maintenance hydration for 6 h or longer. With an online randomisation system that used unequal block sizes, we randomly assigned patients (1:1) to receive either isotonic intravenous fluid containing 140 mmol/L of sodium (Na140) or hypotonic fluid containing 77 mmol/L of sodium (Na77) for 72 h or until their intravenous fluid rate decreased to lower than 50% of the standard maintenance rate. We stratified assignment by baseline sodium concentrations. Study investigators, treating clinicians, nurses, and patients were masked to treatment assignment. The primary outcome was occurrence of hyponatraemia (serum sodium concentration <135 mmol/L with a decrease of at least 3 mmol/L from baseline) during the treatment period, analysed by intention to treat. The trial was registered with the Australian New Zealand Clinical Trials Registry, number ACTRN1260900924257.

FINDINGS

Between Feb 2, 2010, and Jan 29, 2013, we randomly assigned 690 patients. Of these patients, primary outcome data were available for 319 who received Na140 and 322 who received Na77. Fewer patients given Na140 than those given Na77 developed hyponatraemia (12 patients [4%] vs 35 [11%]; odds ratio [OR] 0·31, 95% CI 0·16-0·61; p=0·001). No clinically apparent cerebral oedema occurred in either group. Eight patients in the Na140 group (two potentially related to intravenous fluid) and four in the Na77 group (none related to intravenous fluid) developed serious adverse events during the treatment period. One patient in the Na140 had seizures during the treatment period compared with seven who received Na77.

INTERPRETATION

Use of isotonic intravenous fluid with a sodium concentration of 140 mmol/L had a lower risk of hyponatraemia without an increase in adverse effects than did fluid containing 77 mmol/L of sodium. An isotonic fluid should be used as intravenous fluid for maintenance hydration in children.

FUNDING

National Health and Medical Research Council, Murdoch Childrens Research Institute, The Royal Children's Hospital, and the Australian and New Zealand College of Anaesthetists.

Controversies in nutritional support for critically ill children

Nutritional support for critically ill infants and children is of paramount importance and can greatly affect the outcome of these patients. The energy requirement of children is unique to their size, gestational age, and physiologic stress, and the treatment algorithms developed in adult intensive care units cannot easily be applied to pediatric patients. This article reviews some of the ongoing controversial topics of fluid, electrolyte, and nutritional support for critically ill pediatric patients focusing on glycemic control and dysnatremia. The use of enteral and parenteral nutrition as well as parenteral nutritional-associated cholestasis will also be discussed.

The efficacy of isotonic and hypotonic intravenous maintenance fluid for pediatric patients: a meta-analysis of randomized controlled trials

AIM

This study aimed to analyze the effect of isotonic versus hypotonic solution as intravenous maintenance fluid on level of plasma sodium in hospitalized children.

METHODS

A fully recursive literature search in May 2013 was conducted in PubMed and EMBASE to identify potentially relevant randomized controlled trials. Jadad score and allocation concealment were adopted to evaluate the methodological quality of each trial. RevMan5.2 was used for statistical analysis.

RESULTS

Eight randomized controlled trials with 752 patients were included. Combined analysis showed a significant lower risk of hyponatremia with isotonic solution (odds ratio, 0.36; 95% confidence interval, 0.26-0.51). The isotonic intravenous maintenance did not increase the possibility of hypernatremia (odds ratio, 0.86; 95% confidence interval, 0.36-2.06).

CONCLUSIONS

The meta-analysis revealed that there was potential risk of hyponatremia for routine infusion of hypotonic maintenance fluid. The use of isotonic solution was warranted in hospitalized pediatric patients.

Isotonic intravenous maintenance fluid reduces hospital acquired hyponatremia in young children with central nervous system infections

OBJECTIVE

To find the appropriate type of intravenous fluid (isotonic vs. hypotonic saline in 5 % dextrose) for empiric maintenance fluid therapy in children with central nervous system (CNS) infections that reduces the incidence of hospital acquired hyponatremia.

METHODS

This blinded randomized controlled trial included hospitalized children aged 3 mo to 5 y with suspected CNS infections requiring intravenous maintenance fluid for at least 24 h. The subjects were randomized to receive 0.9 % saline (Group-A), 0.45 % saline (Group-B) and 0.18 % saline (Group-C) at standard maintenance rate. The outcome measures were proportion of patients developing hyponatremia (serum sodium < 135 mmol/L) after 24 h and serum sodium values at 6, 12, 18, 24 h of receiving maintenance fluids.

RESULTS

Of the 92 patients enrolled, 31, 30 and 31 patients were randomized to Group A, B and C, respectively. Majority (60.7 %) of the patients in Group-C developed hyponatremia compared with 7.1 % of the children in Group-A and 46.1 % in Group-B. During first 24 h of fluid administration successive fall in the serum sodium values was observed in patients receiving hypotonic fluids. The risk of developing hyponatremia was nearly 6½ (95 % confidence interval (CI) 1.6-26) to 8.5 (95 % CI 2.16-33.39) times more in patients who received hypotonic saline compared to those who received isotonic saline.

CONCLUSIONS

Administration of 0.9 % saline in 5 % dextrose as intravenous maintenance fluid in children with CNS infection leads to significantly less incidence of hyponatremia when compared to that with hypotonic fluids.

Isotonic versus hypotonic solutions for maintenance intravenous fluid administration in children

BACKGROUND

Maintenance intravenous fluids are frequently used in hospitalised children who cannot maintain adequate hydration through enteral intake. Traditionally used hypotonic fluids have been associated with hyponatraemia and subsequent morbidity and mortality. Use of isotonic fluid has been proposed to reduce complications.

OBJECTIVES

To establish and compare the risk of hyponatraemia by systematically reviewing studies where isotonic is compared with hypotonic intravenous fluid for maintenance purposes in children.Secondly, to compare the risk of hypernatraemia, the effect on mean serum sodium concentration and the rate of attributable adverse effects of both fluid types in children.

SEARCH METHODS

We ran the search on 17 June 2013. We searched the Cochrane Injuries Group Specialised Register, Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library), MEDLINE (OvidSP), Embase (OvidSP), and ISI Web of Science. We also searched clinical trials registers and screened reference lists. We updated this search in October 2014 but these results have not yet been incorporated.

SELECTION CRITERIA

We included randomised controlled trials that compared isotonic versus hypotonic intravenous fluids for maintenance hydration in children.

DATA COLLECTION AND ANALYSIS

At least two authors assessed and extracted data for each trial. We presented dichotomous outcomes as risk ratios (RR) with 95% confidence intervals (CIs) and continuous outcomes as mean differences with 95% CIs.

MAIN RESULTS

Ten studies met the inclusion criteria, with a total of 1106 patients. The majority of the studies were performed in surgical or intensive care populations (or both). There was considerable variation in the composition of intravenous fluid, particularly hypotonic fluid, used in the studies. There was a low risk of bias for most of the included studies. Ten studies provided data for our primary outcome, a total of 449 patients in the analysis received isotonic fluid, while 521 received hypotonic fluid. Those who received isotonic fluid had a substantially lower risk of hyponatraemia (17% versus 34%; RR 0.48; 95% CI 0.38 to 0.60, high quality evidence). It is unclear whether there is an increased risk of hypernatraemia when isotonic fluids are used (4% versus 3%; RR 1.24; 95% CI 0.65 to 2.38, nine studies, 937 participants, low quality evidence), although the absolute number of patients developing hypernatraemia was low. Most studies had safety restrictions included in their methodology, preventing detailed investigation of serious adverse events.

AUTHORS' CONCLUSIONS

Isotonic intravenous maintenance fluids with sodium concentrations similar to that of plasma reduce the risk of hyponatraemia when compared with hypotonic intravenous fluids. These results apply for the first 24 hours of administration in a wide group of primarily surgical paediatric patients with varying severities of illness.

Impact of perioperative hyponatremia in children: A narrative review

For more than 50 years, hypotonic fluids (crystalloids) have been the standard for maintenance fluid used in children. In the last decade, several studies have evaluated the risk of hyponatremia associated with the use of hypotonic vs isotonic fluids, which has lead to an intense debate. Children undergoing surgery have several stimuli for release of antidiuretic hormone, which controls renal water handling, including pain, nausea, vomiting, narcotic use and blood loss. The body’s primary defense against the development of hyponatremia is the ability of the kidneys to excrete free water and dilute urine. Increased levels of antidiuretic hormone can result in hyponatremia, defined as a plasma sodium level < 136 mmol/L, which causes cells to draw in excess water and swell. This manifests as central nervous system symptoms such as lethargy, irritability and seizures. The risk for symptomatic hyponatremia is higher in children than in adults. It represents an emergency condition, and early diagnosis, prompt treatment and close monitoring are essential to reduce morbidity and mortality. The widespread use of hypotonic fluids in children undergoing surgery is a matter of concern and more focus on this topic is urgently needed. In this paper, we review the literature and describe the impact of perioperative hyponatremia in children.

Hypotonic versus isotonic fluids in hospitalized children: a systematic review and meta-analysis

OBJECTIVE

To determine whether the use of hypotonic vs isotonic maintenance fluids confers an increased risk of hyponatremia in hospitalized children.

STUDY DESIGN

A search of MEDLINE (1946 to January 2013), the Cochrane Central Registry (1991 to December 2012), Cumulative Index for Nursing and Allied Health Literature (1990 to December 2012), and Pediatric Academic Societies (2000-2012) abstracts was conducted using the terms "hypotonic fluids/saline/solutions" and "isotonic fluids/saline/solutions," and citations were reviewed using a predefined protocol. Data on the primary and secondary outcomes were extracted from original articles by 2 authors independently. Meta-analyses of the primary and secondary outcomes were performed when possible.

RESULTS

A total of 1634 citations were screened. Ten studies (n = 893) identified as independent randomized controlled trials were included. Five studies examined subjects in the intensive care unit setting, including 4 on regular wards and 1 in a mixed setting. In hospitalized children receiving maintenance intravenous fluids, hyponatremia was seen more often in those receiving hypotonic fluids than in those receiving isotonic fluids, with an overall relative risk of 2.37 (95% CI, 1.72-3.26). Receipt of hypotonic fluids was associated with a relative risk of moderate hyponatremia (<130 mmol/L) of 6.1 (95% CI, 2.2-17.3). A subgroup analysis of hypotonic fluids with half-normal saline found a relative risk of hyponatremia of 2.42 (95% CI, 1.32-4.45).

CONCLUSION

In hospitalized children in intensive care and postoperative settings, the administration of hypotonic maintenance fluids increases the risk of hyponatremia when compared with administration of isotonic fluids. For patients on general wards, insufficient data are available based on the reviewed studies, and individual risk factors must be assessed.

Neurological symptoms in hospitalised patients: do we assess hyponatraemia with sufficient care?

AIM

To review the incidence of hyponatraemic encephalopathy in children treated in a tertiary care centre hospital, together with the clinical setting and clinical management of these cases.

METHODS

Retrospective descriptive study by chart review of patients admitted to hospital during 2000-2010. Patients older than 1 month were included who had severe hyponatraemia (sodium concentration <125 mmol/L) on admission or during their hospital stay and co-incidental neurological symptoms. Epidemiological, clinical, laboratory and therapeutic data were collected.

RESULTS

We analysed 41 cases of severe hypotonic hyponatraemia and neurological symptoms compatible with hyponatraemic encephalopathy. Boys accounted for 56.1% patients, and the median age was 1 year. Hyponatraemia was acquired in hospital by 61% of the patients, and 88% of those patients were receiving intravenous hypotonic fluids. The most frequent neurological symptom was seizures. The most common therapeutic strategy was sodium supplementation and antiepileptic drugs. Hypertonic fluids were only used in the initial treatment of 16 patients. There were two deaths related to hyponatraemic encephalopathy.

CONCLUSION

Hyponatraemia should always be considered a cause of neurological symptoms in hospitalised patients. Treatment should be prompt to prevent neurological sequelae and death. Current recommendations for fluid management in hospitalised children should be reviewed.

Isotonic versus hypotonic maintenance IV fluids in hospitalized children: a meta-analysis

OBJECTIVE

To assess evidence from randomized controlled trials (RCTs) on the safety of isotonic versus hypotonic intravenous (IV) maintenance fluids in hospitalized children.

METHODS

We searched PubMed, Embase, Cochrane Library, and clinicaltrials.gov (up to April 11, 2013) for RCTs that compared isotonic to hypotonic maintenance IV fluid therapy in hospitalized children. Relative risk (RR), weighted mean differences, and 95% confidence intervals (CIs) were calculated based on the effects on plasma sodium (pNa). The risk of developing hyponatremia (pNa <136 mmol/L), severe hyponatremia (pNa <130 mmol/L), and hypernatremia (pNa >145 mmol/L) was evaluated. We adopted a random-effects model in all meta-analyses. Sensitivity analyses by missing data were also performed.

RESULTS

Ten RCTs were included in this review. The meta-analysis showed significantly higher risk of hypotonic IV fluids for developing hyponatremia (RR 2.24, 95% CI 1.52 to 3.31) and severe hyponatremia (RR 5.29, 95% CI 1.74 to 16.06). There was a significantly greater fall in pNa in children who received hypotonic IV fluids (-3.49 mmol/L versus isotonic IV fluids, 95% CI -5.63 to -1.35). No significant difference was found between the 2 interventions in the risk of hypernatremia (RR 0.73, 95% CI 0.22 to 2.48). None of the findings was sensitive to imputation of missing data.

CONCLUSIONS

Isotonic fluids are safer than hypotonic fluids in hospitalized children requiring maintenance IV fluid therapy in terms of pNa.

Association between maintenance fluid tonicity and hospital-acquired hyponatremia

OBJECTIVE

To evaluate whether the administration of hypotonic fluids compared with isotonic fluids is associated with a greater risk for hyponatremia in hospitalized children.

STUDY DESIGN

Informatics-enabled cohort study of all hospitalizations at Lucile Packard Children's Hospital between April 2009 and March 2011. Extraction and analysis of electronic medical record data identified normonatremic hospitalized children who received either hypotonic or isotonic intravenous maintenance fluids upon admission. The primary exposure was the administration of hypotonic maintenance fluids, and the primary outcome was the development of hyponatremia (serum sodium <135 mEq/L).

RESULTS

A total of 1048 normonatremic children received either hypotonic (n = 674) or isotonic (n = 374) maintenance fluids upon admission. Hyponatremia developed in 260 (38.6%) children who received hypotonic fluids and 104 (27.8%) of those who received isotonic fluids (unadjusted OR 1.63; 95% CI 1.24-2.15, P < .001). After we controlled for intergroup differences and potential confounders, patients receiving hypotonic fluids remained more likely to develop hyponatremia (aOR 1.37, 95% CI 1.03-1.84). Multivariable analysis identified additional factors associated with the development of hyponatremia, including surgical admission (aOR 1.44, 95% CI 1.09-1.91), cardiac admitting diagnosis (aOR 2.08, 95% CI 1.34-3.20), and hematology/oncology admitting diagnosis (aOR 2.37, 95% CI 1.74-3.25).

CONCLUSIONS

Hyponatremia was common regardless of maintenance fluid tonicity; however, the administration of hypotonic maintenance fluids compared with isotonic fluids was associated with a greater risk of developing hospital-acquired hyponatremia. Additional clinical characteristics modified the hyponatremic effect of hypotonic fluid, and it is possible that optimal maintenance fluid therapy now requires a more individualized approach.

Intravenous maintenance fluids revisited

Intravenous maintenance fluid therapy aims to replace daily urinary and insensible losses for ill children in whom adequate enteric administration of fluids is contraindicated or infeasible. The traditional determination of fluid volumes and composition dates back to Holliday and Segar's seminal article from 1957, which describes the relationship between weight, energy expenditure, and physiologic losses in healthy children. Combined with estimates of daily electrolyte requirements, this information supports the use of the hypotonic maintenance fluids that were widely used in pediatric medicine. However, using hypotonic intravenous fluids in a contemporary hospitalized patient who may have complex physiologic derangements, less caloric expenditure, decreased urinary output, and elevated antidiuretic hormone levels is often not optimal; evidence over the last 2 decades shows that it may lead to an increased incidence of hyponatremia. In this review, we present the evidence for using isotonic rather than hypotonic fluids as intravenous maintenance fluid.

Hospital-acquired hyponatremia in pediatric patients: a review of the literature

Hypotonic intravenous (IV) fluids in children are a mainstay of therapy based on a recommendation made in 1957 by Holliday and Segar. Since that time, hospital-acquired hyponatremia caused by hypotonic IV fluids has been found to be an additional risk factor in the cause of death and neurological impairment in acutely ill children. This article reviews and critically evaluates the literature regarding the association of hyponatremia and hypotonic IV fluids in pediatric hospitalized, postoperative, and critical care patients.