Clinical settings and vasopressin function in hyponatraemic children

Management Challenges in a Child with Chronic Hyponatremia: Use of V2 Receptor Antagonist

Chronic hyponatremia is very rare in children and is often seen in the setting of congestive heart failure or liver failure in adults. Here, we report an 8-year-old child with hypothalamic glioma who presented with severe hyponatremia. Initial management consisted of fluid restriction. This was very difficult for the child to follow and the child developed bizarre drinking habits requiring intervention from child psychiatry. So therapy was initiated with low dose V2 receptor antagonist under close inpatient monitoring. While initial response was reassuring, her sodium levels tended to drift down with longer duration of treatment requiring us to increase the dose frequently. Her response to therapy and her stable clinical situation off therapy suggest that she may have reset osmostat.

Hospital-acquired hyponatremia—why are hypotonic parenteral fluids still being used?

Hospital-acquired hyponatremia can be lethal. There have been multiple reports of death or permanent neurological impairment in both children and adults. The main factor contributing to the development of hospital-acquired hyponatremia is routine use of hypotonic fluids in patients in whom the excretion of free water, which is retained in response to excess arginine vasopressin (AVP), might be impaired. The practice of administering hypotonic parental fluids was established over 50 years ago, before recognition of the fact that there are numerous potential stimuli for AVP production in most hospitalized patients. Virtually all neurological morbidity resulting from hospital-acquired hyponatremia has been associated with administration of hypotonic fluids. Multiple prospective studies have shown that 0.9% NaCl is effective prophylaxis against hyponatremia. There is not a single report in the literature of neurological complications resulting from the use of 0.9% NaCl in non-neurosurgical patients. Patients at greatest risk of developing hyponatremic encephalopathy following hypotonic fluid administration are children, premenopausal females, postoperative patients, and those with brain injury or infection, pulmonary disease or hypoxemia. When hyponatremic encephalopathy develops, immediate administration of 3% NaCl is essential. In this Review, we discuss the question of why administering hypotonic fluids is unphysiologic and potentially dangerous, the settings in which isotonic fluids should be administered to prevent hyponatremia, and the appropriate treatment of hyponatremic encephalopathy.

Fluid therapy for children: facts, fashions and questions

Fluid therapy restores circulation by expanding extracellular fluid. However, a dispute has arisen regarding the nature of intravenous therapy for acutely ill children following the development of acute hyponatraemia from overuse of hypotonic saline. The foundation on which correct maintenance fluid therapy is built is examined and the difference between maintenance fluid therapy and restoration or replenishment fluid therapy for reduction in extracellular fluid volume is delineated. Changing practices and the basic physiology of extracellular fluid are discussed. Some propose changing the definition of "maintenance therapy" and recommend isotonic saline be used as maintenance and restoration therapy in undefined amounts leading to excess intravenous sodium chloride intake. Intravenous fluid therapy for children with volume depletion should first restore extracellular volume with measured infusions of isotonic saline followed by defined, appropriate maintenance therapy to replace physiological losses according to principles established 50 years ago.

Fatal child abuse by forced water intoxication

BACKGROUND

Although water intoxication leading to brain damage is common in children, fatal child abuse by forced water intoxication is virtually unknown.

METHODS

During the prosecution of the homicide of an abused child by forced water intoxication, we reviewed all similar cases in the United States where the perpetrators were found guilty of homicide. In 3 children punished by forced water intoxication who died, we evaluated: the types of child abuse, clinical presentation, electrolytes, blood gases, autopsy findings, and the fate of the perpetrators.

FINDINGS

Three children were forced to drink copious amounts of water (over 6 L). All had seizures, emesis, and coma, presenting to hospitals with hypoxemia (PO2 = 44 +/- 8 mm Hg) and hyponatremia (plasma Na = 112 +/- 2 mmol/L). Although all showed evidence of extensive physical abuse, the history of forced water intoxication was not revealed to medical personnel, thus none of the 3 children were treated for their hyponatremia. All 3 patients died and at autopsy had cerebral edema and aspiration pneumonia. The perpetrators of all three deaths by forced water intoxication were eventually tried and convicted.

INTERPRETATION

Forced water intoxication is a new generally fatal syndrome of child abuse that occurs in children previously subjected to other types of physical abuse. Patients present with coma, hyponatraemia, and hypoxemia of unknown etiology. If health providers were made aware of the association, the hyponatremia is potentially treatable.

Arginine vasopressin and renin in acutely ill children: implication for fluid therapy

The hypothesis was tested that in young children when admitted to the hospital for acute illness, vasoactive hormone levels are raised. The plasma concentration of arginine vasopressin (AVP) and plasma renin activity (PRA) were measured in 103 acutely ill infants and children admitted to the hospital. Compared to 31 control children with elective surgery, plasma AVP and PRA levels were significantly elevated and plasma osmolality reduced in acute illness, indicating non-osmotic, cardiovascular AVP release. AVP and PRA elevations were found to be independent of the underlying diseases (e.g. respiratory infections, gastroenteritis, bacterial infections and the viral syndrome). Since cardiovascular AVP activation bears the risk of hyponatraemia in the case of hypotonic fluid therapy, initial fluid management should be performed with solutions containing half-normal or normal saline in acutely ill children.

Hyponatraemia and hyperkalaemia in acute pyelonephritis without urinary tract anomalies

Three children with severe hyponatraemia and hyperkalaemia associated with acute pyelonephritis are reported. All were very young male infants in a poor general condition and seriously dehydrated. Diagnostic procedures did not detect obstructive uropathy or vesico-ureteric reflux.

CONCLUSION

Hyponatraemia and hyperkalaemia occurs in young infants with severe acute pyelonephritis in the absence of obstructive uropathy or vesico-ureteric reflux. The severe inflammation of the kidney itself may explain the electrolyte disturbance by a transient resistance of the distal tubule to aldosterone.

Urinary excretion of aldosterone, arginine vasopressin and cortisol in premature infants with maximum renal acid stimulation

Of 452 low-birth-weight infants who were routinely screened for maximum renal acid stimulation (MRAS) (urine pH < 5.4), 149 episodes of incipient late metabolic acidosis (urine pH < 5.4 on 2 consecutive days) were randomly allocated to either a control group or treatment with NaHCO3 or NaCl (2 mmol/kg/day each) for 7 days. Urinary excretion of aldosterone-18-glucuronide (Aldo), arginine vasopressin (AVP) and cortisol was determined in timed urine samples. On day 1, patients with MRAS showed a tendency towards increased urinary excretion of Aldo compared with infants without MRAS. In patients who received alkali therapy, urinary excretion of Aldo, AVP and cortisol decreased or showed a trend to lower values from day 1 to day 7, whereas in patients with MRAS but no specific therapy, Aldo and AVP showed a tendency to increase. We concluded that persistent MRAS is not only characterized by a reduced rate of weight gain and a tendency to decreased nitrogen assimilation, but also increased secretion of Aldo and AVP.