Hypophosphatemia in children hospitalized within an intensive care unit

Hypophosphataemia definitions, incidence and associated outcomes in paediatric intensive care: A retrospective cohort study in post-cardiac surgical patients <2 years of age

AIM

Hypophosphataemia has been linked to higher morbidity and mortality in intensive care but there is inconsistency in the definition of hypophosphataemia for infants and children. We aimed to determine the incidence of hypophosphataemia in a group of at-risk children in paediatric intensive care unit (PICU) and associations with patient characteristics and clinical outcomes using three different hypophosphataemia thresholds.

METHODS

Retrospective cohort study of 205 post-cardiac surgical patients <2 years of age admitted to Starship Child Health PICU, Auckland, New Zealand. Patient demographics and routine daily biochemistry for 14 days after PICU admission were collected. Rates of sepsis, mortality and length of mechanical ventilation were compared between groups with different serum phosphate concentrations.

RESULTS

Out of 205 children, 6 (3%), 50 (24%) and 159 (78%) had hypophosphataemia at thresholds of <0.7, <1.0 and <1.4 mmol/L, respectively. There were no differences in gestational age at birth, sex, ethnicity or mortality in those with and without hypophosphataemia at any threshold. Children with a serum phosphate <1.4 mmol/L had more mean (SD) total hours of mechanical ventilation (85.2 (79.6) vs. 54.9 (36.2) h, P = 0.02) and those with mean serum phosphate <1.0 mmol/L had more mean hours of mechanical ventilation (119.4 (102.8) vs. 65.2 (54.8) h, P < 0.0001), episodes of sepsis (14% vs. 5%, P = 0.03) and longer length of stay (6.4 (4.8-20.7) vs. 4.9 (3.9-6.8) days, P = 0.02).

CONCLUSIONS

Hypophosphataemia is common in this PICU cohort and serum phosphate <1.0 mmol/L is associated with increased morbidity and length of stay.

Hypophosphatemia in infants with severe bronchiolitis and association with length of mechanical ventilation

OBJECTIVES

Electrolyte disorders occurs frequently in children with bronchiolitis. The aim of the present study was to describe the frequency of hypophosphatemia and to evaluate its association with length of mechanical ventilation in infants admitted to a pediatric intensive care unit (PICU) with bronchiolitis.

METHODS

This retrospective cohort study included infants aged between 7 days and 3 months admitted to a PICU between September 2018 and March 2020 and diagnosed with severe acute bronchiolitis requiring respiratory support. Infants with a chronic condition that could potentially be a confounding factor were excluded. The primary outcome was the frequency of hypophosphatemia (<1.55 mmol/L); the secondary outcomes were the frequency of hypophosphatemia during the PICU stay, and the association with length of mechanical ventilation (LOMV).

RESULTS

Among the 319 infants admitted 178 had at least one phosphatemia value and were included in the study. The frequency of hypophosphatemia was 41% at PICU admission (61/148) and 46% during the PICU stay (80/172). The median [IQR] LOMV was significantly longer in children with hypophosphatemia at admission (109 [65-195] h vs. 67 [43-128] h, p = 0.007), and in multivariable linear regression lower phosphatemia at admission was associated with longer LOMV (p < 0.001) after controlling for severity (PELOD2 score) and weight.

CONCLUSION

Hypophosphatemia was frequent in infants with severe bronchiolitis admitted to a PICU and was associated with a longer LOMV.

Early hypophosphatemia in critically ill children and the effect of parenteral nutrition: A secondary analysis of the PEPaNIC RCT

BACKGROUND & AIMS

Hypophosphatemia during critical illness has been associated with adverse outcome. The reintroduction of enteral or parenteral nutrition, leading to refeeding hypophosphatemia (RFH), has been presented as potential risk factor. We investigated the occurrence of early RFH, its association with clinical outcome, and the impact of early parenteral nutrition (PN) on the development of early RFH in pediatric critical illness.

METHODS

This is a secondary analysis of the PEPaNIC randomized controlled trial (N = 1440), which showed that withholding supplemental parenteral nutrition (PN) for 1 week (late-PN) in the pediatric intensive care unit (PICU) accelerated recovery and reduced new infections compared to early-PN (<24 h). Patients with renal replacement therapy or unavailable phosphate concentrations were excluded from this analysis. Early RFH was defined as serum/plasma phosphate <0.65 mmol/L and a drop of >0.16 mmol/L within 3 days of admission to the PICU. The association between baseline characteristics and early RFH, and the association of early RFH with clinical outcome were investigated using logistic and linear regression models, both uncorrected and corrected for possible confounders. To examine the impact of nutritional intake on phosphate concentrations, structural nested mean models with propensity score and censoring models were used.

RESULTS

A total of 1247 patients were eligible (618 early-PN, 629 late-PN). Early RFH occurred in 40 patients (3%) in total, significantly more in the early-PN group (n = 31, within-group occurrence 5%) than in the late-PN-group (n = 9, within-group occurrence 1%, p < 0.001). Patients who were older (OR 1.14 (95% CI 1.08; 1.21) per year added, p < 0.001) and who had a higher Pediatric Risk of Mortality (PIM3) score had a higher risk of developing early RFH (OR 1.36 (95% CI 1.15; 1.59) per unit added, p < 0.001), whereas patients in the late-PN group had a lower risk of early RFH (OR 0.24 (95% CI 0.10; 0.49), p < 0.001). Early RFH was significantly associated with a 56% longer PICU stay (p = 0.003) and 42% longer hospital stay (p = 0.007), but not with new infections (OR 2.01 (95% CI 0.90; 4.30), p = 0.08) or length of mechanical ventilatory support (OR 1.05 (95% CI -3.92; 6.03), p = 0.68), when adjusted for possible confounders. Increase of parenteral nutrition intake (in % kcal of predicted resting energy expenditure) decreased phosphate concentrations (c = -0.002 (95% CI -0.002; -0.001).

CONCLUSIONS

Early RFH occurred in 3% of critically ill children. Patients randomized to late-PN had a lower chance of developing early RFH, which may be explained by the more gradual build-up of nutrition. As early RFH might impact recovery, it is important to closely monitor phosphate concentrations in patients, especially of those at risk for early RFH.

Association between early elevated phosphate and mortality among critically ill elderly patients: a retrospective cohort study

Background

Phosphate disturbances are relatively common in hospitalized patients, especially in critically ill patients. The abnormal phosphate levels may indicate an abnormal body condition. However, little is known about the association between elevated serum phosphate and outcome in critically ill elderly patients. Therefore, the purpose of the present study was to investigate the association between early elevated phosphate and mortality in critically ill elderly patients.

Methods

The present study was a retrospective cohort study based on the medical information mart for intensive care IV (MIMIC-IV) database. Patients with age ≥60 years old were enrolled in the present study. The primary outcome in the present study was ICU mortality. Univariate and multivariate Cox proportional hazard regression analyses were used to evaluate the association between early elevated phosphate and ICU mortality in critically ill elderly patients.

Results

Twenty-four thousand two hundred eighty-nine patients were involved in this analysis and 2,417 patients died in ICU. The median age of involved patients was 78.4 (67.5, 82.9) years old. The median level of serum phosphate in the survivor group was 3.6 (3.0, 4.3) mg/dL, and the median level of serum phosphate in the non-survivor group was 4.4 (3.4, 5.8) mg/dL. The level of serum phosphate in the non-survivor group was significantly higher than the survivor group (4.4 vs. 3.6, P<0.001). The multivariate Cox proportional hazard regression demonstrated that elevated phosphate was an independent risk factor for ICU mortality, after adjustment for other covariates (HR=1.056, 95%CI: 1.028-1.085, P<0.001).

Conclusions

In critically ill elderly patients, early elevated phosphate was significantly associated with increased ICU mortality.

Correcting hypophosphataemia in a paediatric patient with Sanjad-Sakati syndrome through a single oral dose of potassium phosphate intravenous solution

Sanjad–Sakati syndrome is an autosomal recessive disorder that is quite common in Kuwait. Among a wide range of complications in Sanjad–Sakati syndrome patients is the vulnerability to infections and subsequent hypophosphataemia. Hypophosphataemia is a metabolic alteration that contributes to numerous consequences such as cardiac arrhythmia. Therefore, if hypophosphataemia is left unresolved, it may culminate in death. A 20-month-old boy of 2.5 kg body weight diagnosed with Sanjad–Sakati syndrome was initially admitted to the paediatric intensive care unit after recovering from COVID-19, and then shifted to the general ward. He was diagnosed with recurrent pneumonia and urinary tract infection. After 9 days, the patient showed severe hypophosphataemia with serum phosphate concentration reaching 0.33 mmol/L. Despite the availability of potassium phosphate intravenous solution, it was difficult to administer potassium phosphate intravenously because of the small body size and low body weight of the patient. Therefore, 0.6 mL potassium phosphate containing 2.4 mEq of potassium and 5.3 mEq of phosphate was administered through a nasogastric tube. The patient showed rapid response after a single dose through the nasogastric tube. Such an intervention in Sanjad–Sakati syndrome patients shows possible advantages of shifting drug administration from intravenous to oral route that includes a convenient route of administration, whether in the intensive care unit or in the general ward. Moreover, shifting drug administration from the intravenous to oral route overcomes the risk of cannula-induced infection and reduces nurses’ workload.

Hypophosphatemia in critically ill adults and children - A systematic review

BACKGROUND & AIMS

Phosphate is the main intracellular anion essential for numerous biological processes. Symptoms of hypophosphatemia are non-specific, yet potentially life-threatening. This systematic review process was initiated to gain a global insight into hypophosphatemia, associated morbidity and treatments.

METHODS

A systematic review was conducted (PROSPERO CRD42020163191). Nine clinically relevant questions were generated, seven for adult and two for pediatric critically ill patients, and prevalence of hypophosphatemia was assessed in both groups. We identified trials through systematic searches of Medline, EMBASE, Scopus, Cochrane Central Register of Controlled Trials, CINAHL, and Web of Science. Quality assessment was performed using the Cochrane risk of bias tool for randomized controlled trials and the Newcastle-Ottawa Scale for observational studies.

RESULTS

For all research questions, we identified 2727 titles in total, assessed 399 full texts, and retained 82 full texts for evidence synthesis, with 20 of them identified for several research questions. Only 3 randomized controlled trials were identified with two of them published only in abstract form, as well as 28 prospective and 31 retrospective studies, and 20 case reports. Relevant risk of bias regarding selection and comparability was identified for most of the studies. No meta-analysis could be performed. The prevalence of hypophosphatemia varied substantially in critically ill adults and children, but no study assessed consecutive admissions to intensive care. In both critically ill adults and children, several studies report that hypophosphatemia is associated with worse outcome (prolonged length of stay and the need for respiratory support, and higher mortality). However, there was insufficient evidence regarding the optimal threshold upon which hypophosphatemia becomes critical and requires treatment. We found no studies regarding the optimal frequency of phosphate measurements, and regarding the time window to correct hypophosphatemia. In adults, nutrient restriction on top of phosphate repletion in patients with refeeding syndrome may improve survival, although evidence is weak.

CONCLUSIONS

Evidence on the definition, outcome and treatment of clinically relevant hypophosphatemia in critically ill adults and children is scarce and does not allow answering clinically relevant questions. High quality clinical research is crucial for the development of respective guidelines.

History, epidemiology and prevalence of neonatal bone mineral metabolic disorders

The evolutionary patterns of human migration and historical pre/post-industrial revolution have changed the face of bone metabolic disease through past centuries. Cultural, religious, and lifestyle practices continue to alter nutritional recommendations for this expanding diagnosis. Likewise, modern advancements in the field of neonatology and, more specifically, aggressive nutritional management of premature infants have shaped the epidemiology of neonatal bone metabolism over the past two decades. Decreased use of long-term parenteral nutrition, early fortification of enteral nutrition, and stringent American Academy of Pediatrics (AAP) practice guidelines instituting early supplementation of vitamin D have attributed to improved bone mineralization outcomes in both term and preterm infants. Nevertheless, neonatal bone mineral metabolic disorders remain prevalent. In this review, we provide an in-depth look at the diagnoses, therapeutics, and subset populations-both genetic and non-genetic-affected by neonatal bone mineral metabolic disorders.

Incidence and Clinical Outcome of Hypophosphatemia in Pediatric Burn Patients

The objective of this study is to investigate the factors associated with serum phosphate concentrations in severely burned children and whether hypophosphatemia is associated with outcome. Seventy-eight children with a total body surface area of 24% (6.0-68.5) were retrospectively analyzed for serum phosphate concentrations during the first 10 days of stay in the intensive care unit (ICU). The method of generalized estimating equations was used to evaluate the effect of the exposure variables for serum phosphate concentrations during the study period. Outcome variables were the probability of ICU discharge at 30 days and time on mechanical ventilation. Potential explanatory variables for clinical outcome were hypophosphatemia (serum phosphate <3.8 mg/dL for children <2 years and <3.5 mg/dL for older children), age, sex, percent total body surface area burn, inhalation injury, and severe sepsis and/or septic shock. Competing-risk analysis was applied to calculate the probability of ICU discharge at 30 days, and death was assumed as the competing event. The rate of hypophosphatemia was 79.5%. Serum phosphate concentrations were associated with C-reactive protein (coefficient: -0.63; 95% confidence interval [CI]: -0.96 to -0.30; P = .001). Hypophosphatemia was independently associated with a 68% decrease in the probability of ICU discharge at 30 days (subhazard ratio: -0.32; 95% CI: 0.20, 0.53; P = .001) and an increase of 2.9 days in mechanical ventilation (coefficient: 2.91; 95% CI: 1.16, 4.66; P = .001). Serum phosphate concentrations in pediatric burn patients are associated with the magnitude of inflammatory response. Hypophosphatemia is associated with decreased probability of ICU discharge and increased time on mechanical ventilation.

Phosphate disturbance in critically ill children: Incidence, associated risk factors and clinical outcomes

Background

Hypophosphatemia is one of the common disorders that develop in critically ill patients. It has potential complications and is often unrecognized in those patients.

Objective

Determining the incidence of hypophosphatemia in critically ill children, its association with clinical outcomes and the possible risk factors.

Methods

50 patients were enrolled in the study. Levels of serum phosphate were measured on day 1 and day 7 of PICU (Pediatric intensive care unit) stay. The following variables were analyzed: age, gender, diagnosis on admission, malnutrition, phosphorus intake, clinical severity score on admission OFI (Organ Failure Index) and daily scores PELOD (Pediatric Logistic Organ Dysfunction), sepsis, use of dopamine, furosemide and steroids and assessment of nutrition by z scores.

Results

The incidence of hypophosphatemia on admission was 42%. On seventh day of admission incidence of hypophosphatemia was 62%. Malnutrition was present in 24% of patients, serum phosphorus level was significantly lower in malnourished than in well-nourished children (p value = 0.018). Hypophosphatemia was associated with prolonged PICU length of stay (p < 0.001) but was not associated with increased mortality (p = 0.13). Cases on parenteral nutrition and insufficient oral intake while on mechanical ventilator significantly showed hypophosphatemia (p = 0.017). Hypophosphatemia was associated with the use of furosemide, dopamine, steroids and β2 agonist.

Conclusion

Hypophosphatemia was common in the first 7 days of PICU hospitalization and was associated with prolonged PICU stay, Significant association between hypophosphatemia and duration of use of mechanical ventilation, use of furosemide, dopamine, steroids and β2 agonist.

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Hypophosphatemia was common in the first 7 days of pediatric intensive care unit hospitalization.

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Significant association between hypophosphatemia and duration of use of mechanical ventilation.

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Hypophosphatemia was associated with prolonged pediatric intensive care unit length of stay.

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Hypophosphatemia was associated with use of furosemide, dopamine, steroid and β2 agonist.

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Good nutrition of critically ill children has an important role in improving their clinical condition.

Phosphate homeostasis and disorders

Recent studies of inherited disorders of phosphate metabolism have shed new light on the understanding of phosphate metabolism. Phosphate has important functions in the body and several mechanisms have evolved to regulate phosphate balance including vitamin D, parathyroid hormone and phosphatonins such as fibroblast growth factor-23 (FGF23). Disorders of phosphate homeostasis leading to hypo- and hyperphosphataemia are common and have clinical and biochemical consequences. Notably, recent studies have linked hyperphosphataemia with an increased risk of cardiovascular disease. This review outlines the recent advances in the understanding of phosphate homeostasis and describes the causes, investigation and management of hypo- and hyperphosphataemia.

Hypophosphatemia and its clinical implications in critically ill children: a retrospective study

PURPOSE

The aims of this study were to determine the prevalence of hypophosphatemia and to discuss the clinical implications of hypophosphatemia in critically ill children.

MATERIALS AND METHODS

A retrospective review of the medical records of children admitted to the pediatric intensive care unit from December 2006 to December 2007 was conducted.

RESULTS

In 60.2% (n = 71) of the patients, any serum phosphorous level at admission and at the third day or seventh day after admission to pediatric intensive care unit was in hypophosphatemic range. Sepsis was present in 22.9% (n = 27) of the children studied and was associated with hypophosphatemia (P = .02). Hypophosphatemia was also associated with use of furosemide (P = .04), use of steroid (P = .04), use of β(2) agonist (P = .026), and use of an H(2) blocker (P = .004). There was a significant association between hypophosphatemia and the rate to attain target caloric requirements by enteral route (P = .007). The median time to attain target caloric requirements by enteral route was 2.9 ± 1.9 (0.2-10) days in the normophosphatemic group and 4.4 ± 2.8 (0.3-12) days in the hypophosphatemic group. In the multiple regression model, solely the rate to attain the target caloric requirements by enteral route demonstrated independent association with hypophosphatemia (P = .006; β = .27; 95% confidence interval, 0.02-0.09). Significant association was found between hypophosphatemia and the duration of mechanical ventilation and between hypophosphatemia and pediatric intensive care unit length of stay (P = .02 and P = .001, respectively).

CONCLUSIONS

Critically ill pediatric patients are prone to hypophosphatemia, especially if they cannot be fed early by enteral route. Hypophosphatemia is associated with an increased duration of mechanical ventilation and increased length of stay in the pediatric intensive care unit, suggesting that active repletion might improve these parameters.

Hypophosphatemia in critically ill children: prevalence and associated risk factors

BACKGROUND

Hypophosphatemia is a disorder with potential complications and is often unrecognized in critically ill patients.

AIMS

To identify the prevalence of hypophosphatemia and risk factors associated to this disorder in critically ill children.

METHODS

In a prospective cohort study, 82 children admitted consecutively to a pediatric intensive care unit (ICU) were monitored regarding phosphorus serum levels during the first 10 days of admission. The following variables were analyzed as independent for hypophosphatemia: age, gender, diagnosis at admission, malnutrition, phosphorus intake, clinical severity score at admission (pediatric index of mortality 2) and daily scores (Pediatric Logistic Organ Dysfunction), sepsis, use of dopamine, furosemide and steroids, starvation period, and refeeding. Children with a z score of less than -2 of expected weight for age or body mass index (National Center for Health Statistics, 2000) were considered malnourished. Variables significantly associated with hypophosphatemia by bivariate analysis (p < 0.1) were included in a multiple logistic regression model.

RESULTS

The rate of hypophosphatemia was 61% during the first 10 days of pediatric ICU stay, and 12 patients developed hypophosphatemia during the study period. Malnutrition was present in 39.1% of patients, and the sera phosphorus concentration was significantly lower in malnourished than in well-nourished children (2.6 +/- 0.7 mg/dL vs. 3.5 +/- 0.8 mg/dL, p = 0.01). The multiple logistic regression model indicated the diagnosis of acute respiratory disease (odds ratio: 3.22; confidence interval: 1.03-10.1; p = 0.04), use of dopamine (odds ratio: 8.65; confidence interval: 1.58-47.3; p = 0.01), and malnutrition (odds ratio: 3.96; confidence interval: 1.19-13.3; p = 0.02) as independent risk factors for hypophosphatemia. None of the other potential risk factors discriminated for hypophosphatemia.

CONCLUSIONS

Hypophosphatemia was common in the first 10 days of ICU hospitalization and was associated with the diagnosis of respiratory disease, use of dopamine, and malnutrition. These factors should be taken into account during clinical follow up of critically ill children, especially when these conditions are found together.

Structure-function aspects of PstS in multi-drug-resistant Pseudomonas aeruginosa

The increasing prevalence of multi-drug-resistant (MDR) strains of Pseudomonas aeruginosa among critically ill humans is of significant concern. In the current study, we show that MDR clinical isolates of P. aeruginosa representing three distinct genotypes that display high virulence against intestinal epithelial cells, form novel appendage-like structures on their cell surfaces. These appendages contain PstS, an extracellular phosphate binding protein. Using anti-PstS antibodies, we determined that the PstS-rich appendages in MDR strains are involved in adherence to and disruption of the integrity of cultured intestinal epithelial cell monolayers. The outer surface-expressed PstS protein was also identified to be present in P. aeruginosa MPAO1, although to a lesser degree, and its role in conferring an adhesive and barrier disruptive phenotype against intestinal epithelial cells was confirmed using an isogenic DeltaPstS mutant. Formation of the PstS rich appendages was induced during phosphate limitation and completely suppressed in phosphate-rich media. Injection of MDR strains directly into the intestinal tract of surgically injured mice, a known model of phosphate limitation, caused high mortality rates (60%-100%). Repletion of intestinal phosphate in this model completely prevented mortality. Finally, significantly less outer surface PstS was observed in the MPAO1 mutant DeltaHxcR thus establishing a role for the alternative type II secretion system Hxc in outer surface PstS expression. Gene expression analysis performed by RT-PCR confirmed this finding and further demonstrated abundant expression of pstS analogous to pa5369, pstS analogous to pa0688/pa14-55410, and hxcX in MDR strains. Taken together, these studies provide evidence that outer surface PstS expression confers a highly virulent phenotype of MDR isolates against the intestinal epithelium that alters their adhesive and barrier disrupting properties against the intestinal epithelium.