Common fluid and electrolyte problems in the pediatric intensive care unit

Interventions for non-oliguric hyperkalaemia in preterm neonates

BACKGROUND

Non-oliguric hyperkalaemia of the newborn is defined as a plasma potassium level > 6.5 mmol/L in the absence of acute renal failure. Hyperkalaemia is a common complication in the first 48 hours of life in very low birth weight (VLBW) (birth weight < 1500 g) and/or very preterm newborns (≤32 weeks gestational age).

OBJECTIVES

To determine the effectiveness and safety of interventions for non-oliguric hyperkalaemia [for the purpose of this review defined as serum potassium > 6.0 mmol/L (the clinical setting in which interventions would likely be introduced prior to reaching a grossly abnormal level) and urine output > 0.5 ml/kg/hour] in preterm or VLBW infants during their first 72 hours of life.

SEARCH METHODS

The Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 2, 2006) was searched to identify relevant randomised and quasi-randomised controlled trials. The following data bases were searched in June 2006; MEDLINE from 1966, EMBASE from 1980, CINAHL from 1982. Search updated in June 2011.

SELECTION CRITERIA

Randomised or quasi-randomised controlled trials conducted in preterm and/or VLBW neonates with a diagnosis of non-oliguric hyperkalaemia. Interventions included were those aimed at redistributing serum potassium (sodium bicarbonate or insulin and glucose) or increasing the elimination of potassium from the body [diuretics (any type) or ion exchange resins (any type), or exchange transfusion, or peritoneal dialysis, or salbutamol, or albuterol] or counteracting potential arrhythmias from hyperkalaemia (calcium) versus placebo or no intervention; or comparing any two of these interventions. Primary outcome measure was 'All cause mortality during initial hospital stay'. Secondary outcomes included common adverse outcomes seen in preterm infants.

DATA COLLECTION AND ANALYSIS

We used the standard review methods of the Cochrane Neonatal Review Group. Two authors assessed all studies identified as potentially relevant by the literature search for inclusion in the review. Statistical methods included relative risk (RR), risk difference (RD), number needed to treat to benefit (NNTB) or number needed to treat to harm (NNTH) for dichotomous and weighted mean difference (WMD) for continuous outcomes reported with 95% confidence intervals (CI). We used a fixed effect model for meta-analysis. Heterogeneity was assessed using the I squared (I(2) ) statistic.

MAIN RESULTS

Three randomised trials, enrolling 74 preterm infants (outcome data available on 71 infants) evaluated interventions for hyperkalaemia. Urine output was ascertained in only one study (Hu 1999). In none of the trials could we ascertain that allocation to the comparison groups was concealed. The sample sizes of the three trials were very small with 12 (Malone 1991), 19 (Singh 2002) and 40 infants enrolled (Hu 1999). The intervention and the outcome assessments could not be blinded to the clinical staff in two trials (Malone 1991; Hu 1999).One study (Malone 1991), glucose and insulin, compared to cation-exchange resin, caused a reduction in all cause mortality that was of borderline statistical significance: RR 0.18 (95% CI 0.03 to 1.15); RD -0.66 (95% CI -1.09 to -0.22); NNTB 2 (95% CI 1 to 5)]. In the study of Hu (Hu 1999), the incidence of intraventricular haemorrhage ≥ grade 2 was significantly reduced [RR 0.30 (95% CI 0.10 to 0.93); RD -0.35 (95% CI -0.62 to -0.08); NNTB 3 (95% CI 2 to 13).Albuterol inhalation versus saline inhalation changed serum K+ from baseline at four hours [WMD -0.69 mmol/L (95% CI -0.87 to -0.51)] and at eight hours [WMD -0.59 mmol/L (95% CI -0.78 to -0.40)] after initiation of treatment. No differences noted in mortality or other clinical outcomes (Singh 2002).No serious side effects were noted with either the combination of insulin and glucose or albuterol inhalation. Other interventions listed in our objectives have not been studied to date.

AUTHORS' CONCLUSIONS

In view of the limited information from small studies of uncertain quality, no firm recommendations for clinical practice can be made. It appears that the combination of insulin and glucose is preferred over treatment with rectal cation-resin for hyperkalaemia in preterm infants. Both the combination of insulin and glucose and albuterol inhalation deserve further study. The two interventions could possibly be tested against each other. The effectiveness of other potentially effective interventions for non-oliguric hyperkalaemia (diuretics, exchange transfusion, peritoneal dialysis and calcium) have not been tested in randomised controlled trials.

Cerebral edema in diabetic ketoacidosis

OBJECTIVE

To review the causes of cerebral edema in diabetic ketoacidosis (CEDKA), including pathophysiology, risk factors, and proposed mechanisms, to review the diagnosis, treatment, and prognosis of CEDKA and the treatment of diabetic ketoacidosis as it pertains to prevention of cerebral edema.

DATA SOURCE

A MEDLINE search using OVID was done through 2006 using the search terms cerebral edema and diabetic ketoacidosis. RESULTS OF SEARCH: There were 191 citations identified, of which 150 were used. An additional 42 references listed in publications thus identified were also reviewed, and two book chapters were used.

STUDY SELECTION

The citations were reviewed by the author. All citations identified were used except 25 in foreign languages and 16 that were duplicates or had inappropriate titles and/or subject matter. Of the 194 references, there were 21 preclinical and 40 clinical studies, 35 reviews, 15 editorials, 43 case reports, 29 letters, three abstracts, six commentaries, and two book chapters.

DATA SYNTHESIS

The data are summarized in discussion.

CONCLUSIONS

The causes and mechanisms of CEDKA are unknown. CEDKA may be due as much to individual biological variance as to severity of underlying metabolic derangement of the child's state and/or treatment risk factors. Treatment recommendations for CEDKA and diabetic ketoacidosis are made taking into consideration possible mechanisms and risk factors but are intended as general guidelines only in view of the absence of conclusive evidence.

Interventions for non-oliguric hyperkalaemia in preterm neonates

BACKGROUND

Non-oliguric hyperkalaemia of the newborn is defined as a plasma potassium level > 6.5 mmol/L in the absence of acute renal failure. Hyperkalaemia is a common complication in the first 48 hours of life in very low birth weight (birth weight < 1500 g) and/or very preterm newborns (< 32 weeks gestational age).

OBJECTIVES

To determine the effectiveness and safety of interventions for non-oliguric hyperkalaemia [for the purpose of this review defined as serum potassium > 6.0 mmol/L ( the clinical setting in which interventions would likely be introduced prior to reaching a grossly abnormal level) and a urine output > 0.5 ml/kg/hour] in preterm or very low birth weight (VLBW) infants during their first 72 hours of life.

SEARCH STRATEGY

The Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 2, 2006) was searched to identify relevant randomised and quasi-randomised controlled trials. The following data bases were searched in June 2006; MEDLINE from 1966, EMBASE from 1980, CINAHL from 1982.

SELECTION CRITERIA

Randomised or quasi-randomised controlled trials conducted in preterm and/or VLBW neonates with a diagnosis of non-oliguric hyperkalaemia. The interventions included were those aimed at redistributing serum potassium (sodium bicarbonate or insulin and glucose) or increasing the elimination of potassium from the body [diuretics (any type) or ion exchange resins (any type), or exchange transfusion, or peritoneal dialysis, or salbutamol, or albuterol] or counteracting potential arrhythmias from hyperkalaemia (calcium) vs. placebo or no intervention; or comparing any two of these interventions. The primary outcome measure was 'All cause mortality during initial hospital stay'. Secondary outcomes included common adverse outcomes seen in infants born preterm.

DATA COLLECTION AND ANALYSIS

The standard review methods of the Cochrane Neonatal Review Group were used. All studies identified as potentially relevant by the literature search were assessed for inclusion in the review by the two authors. The statistical methods included relative risk (RR), risk difference (RD), number needed to treat to benefit (NNTB) or number needed to treat to harm (NNTH) for dichotomous and weighed mean difference (WMD) for continuous outcomes reported with 95% confidence intervals (CI). A fixed effects model was used for meta-analysis. Heterogeneity was assessed using the I squared (I(2 )) statistic.

MAIN RESULTS

Three randomized trials, enrolling 74 preterm infants (outcome data available on 71 infants) evaluated interventions for hyperkalemia. Urine output was ascertained only in one study (Hu 1999). In none of the trials could we ascertain that allocation to the comparison groups was concealed. The sample sizes of the three trials were very small with 12 (Malone 1991), 19 (Singh 2002) and 40 infants enrolled (Hu 1999). The intervention and the outcomes assessments could not be blinded to the clinical staff in two trials (Hu 1999; Malone 1991). In one study (Malone 1991), glucose and insulin, compared to cation-exchange resin, caused a reduction in all cause mortality that was of borderline statistical significance: RR 0.18 (95% CI 0.03, 1.15); RD -0.66 (95% CI -1.09, -0.22); NNTB 2 (95% CI 1, 5)]. In the study of Hu (Hu 1999), the incidence of intraventricular haemorrhage > grade 2 was significantly reduced [RR 0.30 (95% CI; 0.10, 0.93); RD -0.35 (95% CI; -0.62, -0.08); NNTB 3 (95% CI; 2, 13). Albuterol inhalation vs. saline inhalation changed serum K+ from baseline at 4 hours [WMD -0.69 mmol/L (95% CI; -0.87, -0.51)] and at 8 hours [WMD -0.59 mmol/L (95% CI; -0.78, -0.40)] after initiation of treatment. No differences were noted in mortality or other clinical outcomes (Singh 2002). No serious side effects were noted with either the combination of insulin and glucose or albuterol inhalation. Other interventions that we listed in our objectives have not been studied to date.

AUTHORS' CONCLUSIONS

In view of the limited information from small studies of uncertain quality, no firm recommendations for clinical practice can be made. It appears that the combination of insulin and glucose is preferred over treatment with rectal cation-resin for hyperkalaemia in preterm infants. Both the combination of insulin and glucose and albuterol inhalation deserve further study. The two interventions could possibly be tested against each other. The effectiveness of other potentially effective interventions for non-oliguric hyperkalaemia (diuretics, exchange transfusion, peritoneal dialysis and calcium) have not been tested in randomized controlled trials.

Pediatric Fluid and Electrolyte Therapy

Fluid and electrolyte therapies in pediatric patients are reviewed. Physiologically, the proportion of body water to body weight is different in infants and children than adults. This difference makes managing the pediatric patient an intricate task. Several factors that may increase or decrease fluid needs are discussed.

The main goals of deficit/replacement and maintenance therapies are reviewed. Laboratory analyses assist in evaluating the types of dehydration states. The degree of dehydration may be established by patient history and physical examination. The 5%, 10%, and 15% rule of dehydration is an adequate method for estimating proper fluid replacement.

Maintenance fluid therapy is evaluated and described for certain pediatric disease states, such as pyloric stenosis, burns, and surgery. Guidelines are presented for each situation, but each patient should be treated on an individual basis.