Welcome to PICU Doc On Call, A Podcast Dedicated to Current and Aspiring Intensivists.
I'm Pradip Kamat and I'm Rahul Damania and we are coming to you from Children's Healthcare of Atlanta - Emory University School of Medicine.
Welcome to our Episode of a 9 year old girl with worsening seizures in the setting of an electrolyte abnormality.
Here's the case:
A 9 year old girl presents to the ED with increased frequency of seizures, dehydration and listlessness. She has h/o of global developmental delay, congenital hydrocephalous (with VP shunt in place with her last revision 3 years prior, and seizure d/o treated with Leviteracetam. She usually has one or two focal seizures per day but on day of admission she had multiple prolonged seizures which were also generalized tonic clonic in semiology. Per her caregiver, the patient usually eats by mouth and mother typically gives her 3 cups of water daily. There is no history of diarrhea but patient has had 2-3 bouts of non-bloody non-bilous emesis on day of presentation. Looking at her growth chart, the patient has also lost ~ 2KG of her weight in the last 3 months and has had poor follow up with her PCP. In the ED she has a hypovolemic shock picture as she is hypothermic, tachycardic, tachpneic, and hypotensive with appropriate saturations. Blood gas is notable for a mild metabolic acidosis. Patient receives abortive seizure rescue. A head CT showed no increased in hydrocephalus, no mass or hemorrhage and a shunt series confirms patency of her VP shunt. Most pertinently to this case, her serum sodium on her RFP was undetectable at a value of = >200mEQ/dL; this was confirmed by a repeat lab draw and POC value. Other notable findings included an elevated Cr for age, an elevated BUN and a microcytic anemia. Patient was given a NS bolus, had cultures drawn, was started on broad spectrum abx therapy, stabilized and sent to the PICU.
To summarize key elements from this case, this patient has:
A history of GDD with epilepsy and shunted hydrocephalus.
A stigmata of cachexia.
And a presentation of hypovolemic shock secondary to decreased intake, increased loss, and potential underlying concern for sepsis.
The most important element of this case is her extreme hypernatremia
All of these factors in this case point to our topic of discussion today → the approach to hypovloemic hypernatremia 2/2 to dehydration.
Let's transition into some history and physical exam components of hypovolemic hypernatremia?

Key history features in patients who present with Hypovolemic HyperNa include:

Increased losses such as emesis
Decreased intake, and in this setting potentially lack of access to free water
Listlessness which could be related to cerebral hypoperfusion
Increase in seizure frequency due to increased rapid depolarization of Na channels in the brain and fluid shifts
And weight loss → all of these factors were seen in our case.
Of note if this patient was a neonate considering a high-pitched cry in the setting of hyperNa & dehydration could be a subtle history finding.

Are there some red-flag symptoms or physical exam components which you could highlight?

Our patient is Non verbal and has global delay secondary to a remote neurological insult
She may not have intact ability to communicate or vocalize thirst.
Apart from her mucous membranes, dry cracked lips, decreased skin turgor that can be described as doughy, and prolonged capillary refill, I think it is important to highlight her hypotension - as BP is one of the last vital signs in pediatrics to be abnormal in intravascular volume depletion. To me, this really stratifies this patient into severe dehydration and potentially septic shock.

This is a great point — understanding % volume loss and its correlation to vital sign and PE anomalies is key. Remember a sensitive marker for dehydration in pediatrics is tachycardia and a late finding if you are primarily dealing with dehydration is hypotension. This...