# Mixed Metabolic and Respiratory Alkalosis: An Uncommon Presentation of Superior Mesenteric Artery Syndrome in an Adolescent Male Patient

## TL;DR

A 16-year-old boy with SMA syndrome showed a rare mix of metabolic and respiratory alkalosis, highlighting the need for early diagnosis and treatment.

## Contribution

This case reports an uncommon acid-base disorder in SMA syndrome, emphasizing atypical presentations in adolescents.

## Key findings

- The patient exhibited a mixed acid-base disorder of metabolic and respiratory alkalosis.
- Strong’s procedure led to successful postoperative recovery and symptom resolution.
- Early diagnosis and intervention are critical to prevent complications in SMA syndrome.

## Abstract

Superior mesenteric artery (SMA) syndrome is an uncommon cause of proximal intestinal obstruction resulting from compression of the third portion of the duodenum between the abdominal aorta and the SMA. Patients typically present with postprandial epigastric pain, bilious vomiting, and weight loss, and most exhibit metabolic alkalosis due to persistent loss of gastric acid. We report the case of a 16-year-old male child with progressive postprandial vomiting and significant nutritional decline who was diagnosed with SMA syndrome on the basis of reduced aortomesenteric angle and marked duodenal dilatation on imaging. Uniquely, the patient demonstrated a mixed acid-base disorder, combining metabolic alkalosis from chronic vomiting with respiratory alkalosis likely secondary to hypoxia-induced hyperventilation. The patient underwent Strong’s procedure with good postoperative recovery and resolution of symptoms. This case emphasizes the importance of recognizing atypical metabolic profiles in SMA syndrome, maintaining clinical suspicion in adolescents with chronic vomiting and weight loss, and intervening early to prevent complications.