Welcome to PICU Doc On Call, A Podcast Dedicated to Current and Aspiring Intensivists.
I'm Pradip Kamat coming to you from Children’s Healthcare of Atlanta/Emory University School of Medicine
and I'm Rahul Damania from Cleveland Clinic Children’s Hospital. We are two Pediatric ICU physicians passionate about all things MED-ED in the PICU. PICU Doc on Call focuses on interesting PICU cases & management in the acute care pediatric setting so let’s get into our episode:
In today's episode, we discuss about a 12-year-old male with lethargy after ingestion.
Here's the case presented by Rahul:
A 12-year-old male is found unresponsive at home. He was previously well and has no relevant past medical history. The mother states that he was recently in an argument with his sister and thought he was going into his room to “have some space.” The mother noticed the patient was in his room for about 1 hour. After coming into the room she noticed him drooling, minimally responsive, and cold to the touch. The patient was noted to be moaning in pain pointing to his abdomen and breathing fast. Dark red vomitus was surrounding the patient. The mother called 911 as she was concerned about his neurological state. With 911 on the way, the mother noticed a set of empty vitamins next to the patient. She noted that these were the iron pills the patient’s sister was on for anemia. EMS arrives for acute stabilization, and the patient is brought to the ED. En route, serum glucose was normal. The patient presents to the ED with hypothermia, tachycardia, tachypnea, and hypertension. His GCS is 8, he has poor peripheral perfusion and a diffusely tender abdomen. He continues to have hematemesis and is intubated for airway protection along with declining neurological status. After resuscitation, he presents to the Pediatric ICU. Upon intubation, an arterial blood gas is drawn. His pH is 7.22/34/110/-6 — serum HCO3 is 16, and his AG is elevated.
To summarize key elements from this case, this patient has:
Lethargy and unresponsiveness after acute ingestion.
His hematemesis is most likely related to his acute ingestion.
And finally, he has an anion gap metabolic acidosis, as evidenced by his low pH and low HCO3.
All of these salient factors bring up the concern for acute iron ingestion! In today’s episode, we will not only go through acute management pearls for iron poisoning, but also go back to the fundamentals, and cover ACID BASE disorders.
We will break this episode down into giving a broad overview of acid base, build a stepwise approach, and apply our knowledge with integrated cases.

We will use a physiologic approach to cover this topic!
Pradip, can you give us a quick overview of some general principles when it comes to tackling this high-yield critical care topic?
Absolutely, internal acid base homeostasis is paramount for maintaining life. Moreover, we know that accurate and timely interpretation of an acid–base disorder can be lifesaving.
When we conceptualize acid base today, we will focus on pH, HCO3, and CO2.
As we go into each disorder keep in mind to always correlate your interpretation of blood gasses to the clinical status of the patient.
Going back to basic chemistry, can you comment on the relationship between CO2 and HCO3?
Yes, now this is a throwback. However, we have to review the Henderson–Hasselbalch equation. The equation has constants & logs involved, however in general this equation shows that the pH is determined by the ratio of the serum bicarbonate (HCO3) concentration and the PCO2, not by the value of either one alone. In general, an acid–base disorder is called “respiratory” when it is caused by a primary abnormality in respiratory function (i.e., a change in the PaCO2) and “metabolic” when the primary change is attributed to a variation in the bicarbonate concentration.
Now that we have some fundamentals down, let’s move into definitions. Can you define acidemia and alkalemia and comment on how...