[Postoperative hyponatremia in children: pathophysiology, diagnosis and treatment]

Postoperative Dysnatremia in Pediatric Patients Undergoing Palatoplasty

OBJECTIVE

Identifying predisposing factors to dysnatremia to improve perioperative care after cleft surgery.

DESIGN

Retrospective case series. Patient data were obtained through the electronic medical records of the hospital.

SETTING

Tertiary care university hospital.

PATIENTS

The inclusion criterion was the measurement of an abnormal natremia value, defined as Na >150 or <130 mmol/l after a cleft lip or cleft palate repair procedure. The exclusion criterion was natremia between 131 and 149 mmol/l.

RESULTS

Natremia measurements were available for 215 patients born between 1995 and 2018. Five patients presented with postoperative dysnatremia. Several predisposing factors to dysnatremia have been identified: drugs, infection, administration of intravenous fluids, and postoperative syndrome of inappropriate antidiuretic hormone secretion. Although the hospital environment contributes to dysnatremia development, the fact that only patients undergoing cleft palate repair develop natremia anomalies suggests that this surgery may be itself a risk factor.

CONCLUSION

Children undergoing palatoplasty may be at higher risk to develop postoperative dysnatremia. Early recognition of symptoms and risk factors, postoperative monitoring, and prompt treatment of dysnatremia diminish the risk of neurological complications.

Clinical Associations of Early Dysnatremias in Critically Ill Neonates and Infants Undergoing Cardiac Surgery

Dysnatremias (DN) are common electrolyte disturbances in cardiac critical illness and are known risk factors for adverse outcomes in certain populations. Little information exists on DN in children with cardiac disease admitted to the cardiac intensive care unit (CICU) after undergoing cardiac surgery, either corrective or palliative. The aim was to determine the incidence and adverse outcomes associated with DN in neonates and infants undergoing cardiac surgery. Retrospective cohort and single center study performed at Children's Hospital Colorado from May 2013 to May 2014, in children under 1 year old admitted to the CICU after undergoing surgery for congenital or acquired cardiac disease. 183 subjects were analyzed.

EXCLUSIONS

subjects that demonstrated DN before surgery. Serum sodium levels were recorded for the first 72 h post-operatively. DN was present in 54% of the subjects (98/183): hypernatremia in 60 (33%), hyponatremia in 38 (21%). Multivariate analysis revealed that mild hypernatremia (146-150 mmol/dl) and moderate hypernatremia (151-155 mmol/dl) were associated with longer hospital length of stay (LOS, p < 0.05) and ventilation times (p < 0.05). No association was shown between mild/moderate hyponatremia (125-134 mmol/dl) with either outcome. Hours to DN were significantly lower in hypernatremic (median = 5.8 h) than hyponatremic (median = 43.8 h) patients (p < 0.001). Children younger than 30 days presented DN at an earlier stage than those 31 days-1 year old (median +2.2 vs. 17.3 h). No associations present between DN and the class of diuretic (loop vs. thiazide) administered, or the route of administration (intravenous bolus vs. constant infusion). Total median sodium bicarbonate administration was associated with hypernatremia, as was exposure to vasopressin within the first 72 h post-operatively. Dysnatremias are common in the early post-operative period in neonates and infants undergoing cardiac surgery. Mild to moderate hypernatremia, but not hyponatremia, is associated with longer LOS and longer ventilation time in infants undergoing cardiovascular surgery. Hypernatremia is also associated with younger infants, a higher surgical complexity, administration of bicarbonate and exposure to vasopressin. Diuretic type or interval timing of intravenous delivery did not demonstrate any effect. Prospective studies are needed in this population, in order to determine how DN, particularly hypernatremia, contributes to adverse outcomes, whether this association is independent of illness severity, and what may be safe treatments and interventions for these disorders.

[How I manage the child who is not awakening as expected]

Regarding immediate post-anaesthesia problems, one must distinguish slow awakening and the apparition of neurologic or behavioural problems. Post-anaesthesia delirium, an usual cause of transient agitation in the recovery room following halogenated-based anaesthetic, is not included in this discussion. There are two false causes of slow awakening: residual curarization and a total spinal. Slow awakening is usually caused by overdose, either absolute or relative. Regarding the occurrence of neurologic or behavioural problems, one must consider situations at risk, patients at risk, the consequences of iatrogenicity but also the unknown cerebral tumour or metabolic disorder.

Postnatal toxic and acquired disorders

To develop and function optimally, the brain requires a balanced environment of electrolytes, amino acids, neurotransmitters, and metabolic substrates. As a consequence, organ dysfunction has the potential to induce brain disorders and toxic-metabolic encephalopathies, particularly when occurring during early stages of cerebral maturation. Induced toxicity of three different organ systems that are commonly associated with brain complications are discussed. First, thyroid hormone deficiency caused by intrinsic or extrinsic factors (e.g., environmental toxins) may induce severe adverse effects on child neurological development from reversible impairments to permanent mental retardation. Second, inadequate removal of wastes due to chronic renal failure leads to the accumulation of endogenous toxins that are harmful to brain function. In uremic pediatric patients, the brain becomes more vulnerable to exogenous substances such as aluminum, which can induce aluminum encephalopathy. Following surgical procedures, neurological troubles including focal defects and severe epileptic seizures may result from hypertensive encephalopathy combined with toxicity of immunomodulating substances, or from the delayed consequences of cardiovascular defect. Taken together, this illustrates that organ disorders clearly have an impact on child brain function in various ways.

[Organization of anaesthesia for children in a non-paediatric hospital]

The author reviews the guidelines and the possible organization of anaesthesia and surgery in a non-paediatric hospital.

Renal salt-wasting syndrome in children with intracranial disorders

Hypotonic hyponatremia, a serious and recognized complication of any intracranial disorder, results from extra-cellular fluid volume depletion, inappropriate anti-diuresis or renal salt-wasting. The putative mechanisms by which intracranial disorders might lead to renal salt-wasting are either a disrupted neural input to the kidney or the elaboration of a circulating natriuretic factor. The key to diagnosis of renal salt-wasting lies in the assessment of extra-cellular volume status: the central venous pressure is currently considered the yardstick for measuring fluid volume status in subjects with intracranial disorders and hyponatremia. Approximately 110 cases have been reported so far in subjects ≤18 years of age (male: 63%; female: 37%): intracranial surgery, meningo-encephalitis (most frequently tuberculous) or head injury were the most common underlying disorders. Volume and sodium repletion are the goals of treatment, and this can be performed using some combination of isotonic saline, hypertonic saline, and mineralocorticoids (fludrocortisone). It is worthy of a mention, however, that some authorities contend that cerebral salt wasting syndrome does not exist, since this diagnosis requires evidence of a reduced arterial blood volume, a concept but not a measurable variable.

[Incidence of hyponatremia and its causes in neurological patients]

INTRODUCTION

Hyponatremia is considered the most frequent electrolyte disorder found in hospitalized patients and seems to be a prognostic factor during hospitalization.

METHODS

A prospective observational study was carried out in consecutive neurological patients admitted to our hospital over a 3-month period. Blood and urinary ionogram and osmolality were determined at entry and 3-5 days after admission in all patients with hyponatremia.

RESULTS

Of the 130 patients admitted, 19 (14.6%) had hyponatremia. The causes of hyponatremia were as follows: inappropriate fluid replacement in 4 patients (21%), antihypertensive drugs in 4 (21%), syndrome of inappropriate secretion of antidiuretic hormone in 4 (21%), cerebral salt wasting syndrome in 2 (10%), and edematous status caused by liver disease in one and digestive loss in one (5%) each. Mortality was one (5%) and 0 (0%) among patients with and without hyponatremia, respectively.

CONCLUSION

Hyponatremia is common in hospitalized neurological patients and can be misdiagnosed as a worsening of the main illness.

The effects of head trauma on hypothalamic-pituitary function in children and adolescents

PURPOSE OF REVIEW

Endocrine dysfunctions have been increasingly recognized following traumatic brain injury. Ever more numerous studies on acute head-injured adults have also raised concern about this risk in children and adolescents who have experienced head injury. The current review of the pediatric literature summarizes recent findings on acute-phase dysfunction and traumatic brain injury-associated hypopituitarism.

RECENT FINDINGS

The pathophysiologic mechanisms underlying acute-phase hyponatremic and hypernatremic disorders have been elucidated. Prospective studies on traumatic brain injury-associated hypopituitarism in pediatric patients are ongoing and preliminary data are available.

SUMMARY

Traumatic brain injury, a 'silent epidemic' that carries a considerable burden of disabilities, leads to a variety of endocrine dysfunctions in 28-69% of adult acute head-injured patients. In the acute posttraumatic phase, adrenal insufficiency and electrolyte disorders are critical conditions. Neurosurgical patients, particularly those prone to neurological damage, require prompt diagnosis. Hypopituitarism may be diagnosed months or years after a traumatic brain injury event. Since growth hormone and gonadotropin secretion are most frequently compromised, careful follow-up of growth and pubertal development is mandatory in children hospitalized for traumatic brain injury.

[Post-tonsillectomy hyponatremia: a posible lethal complication]

Death following tonsillectomy in children is very rare. It is most commonly due to bleeding or aspiration. But, there is another potentially lethal complication following the pediatric tonsillectomy, post-surgical hyponatremia. Acute hyponatremia can lead to catastrophic neurological sequelae. Although this cmplication is not related to the surgical technique, it is potentially life-threatening. The most important factor for hospital acquired hyponatremia is the administration of excessive amounts of hypotonic fluid in situations in wich antidiuretic hormone (ADH) is secreted for non osmotic reasons. We will discuss the etiology and pathophysiology of post-operative hyponatremia. We expect that fatal post-operative hyponatremia can be avoided in pediatric tonsillectomy patients.

Cerebral salt wasting syndrome in children with acute central nervous system injury

The purpose of this investigation was to describe the causes, clinical pattern, and treatment of cerebral salt wasting syndrome in children with acute central nervous system injury. This retrospective study focused on patients<or=15 years old diagnosed with cerebral salt wasting syndrome, over a period of 7 years, in the pediatric intensive care unit of a tertiary care hospital. Selection criteria included evidence of hyponatremia (serum sodium<130 mEq/L), polyuria, elevated urine sodium (>120 mEq/L), and volume depletion. Fourteen patients were identified with cerebral salt wasting syndrome, 12 after a neurosurgical procedure (8 brain tumor, 4 hydrocephalus) and 2 after severe brain trauma. In 11 patients the cerebral salt wasting syndrome was diagnosed during the first 48 hours of admission. Prevalence of cerebral salt wasting syndrome in neurosurgical children was 11.3/1000 surgical procedures. The minimum sodium was 122+/-7 mEq/L, the maximum urine osmolarity 644+/-59 mOsm/kgH2O. The maximum sodium supply was 1 mEq/kg/h (range, 0.1-2.4). The mean duration of cerebral salt wasting syndrome was 6+/-5 days (range 1-9). In conclusion, cerebral salt wasting syndrome can complicate the postoperative course of children with brain injury; it is frequently present after surgery for brain tumors and hydrocephalus and in patients with severe head trauma. Close monitoring of salt and fluid balance is essential to prevent severe neurologic and hemodynamic complications.