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Is acid base determination an accurate predictor of pyloric stenosis?
1Department of Emergency Medicine, Royal Children's Hospital, Parkville, Victoria, Australia.
Insights
Acid base status effectively predicts pyloric stenosis in vomiting infants. Key indicators include pH, chloride, and base excess (BE), offering a valuable screening tool for early diagnosis.
Area of Science:
- Pediatric Gastroenterology
- Clinical Chemistry
Background:
- Pyloric stenosis is a common cause of vomiting in infants.
- Accurate and early diagnosis is crucial for optimal patient outcomes.
Purpose of the Study:
- To evaluate if acid-base status can predict pyloric stenosis in infants presenting with vomiting.
- To identify specific acid-base parameters indicative of pyloric stenosis.
Main Methods:
- Retrospective chart review of 100 infants with pyloric stenosis and 84 controls.
- Comparison of clinical and biochemical parameters, including acid-base status (pH, bicarbonate, base excess).
Main Results:
- Significant predictors of pyloric stenosis included pH, base excess (BE), chloride, and bicarbonate.
- A predictive model using pH > 7.45, chloride < 98, and BE > +3 achieved an 88% positive predictive value.
Conclusions:
- Acid-base determination serves as a valuable screening tool for pyloric stenosis in vomiting infants.
- Further prospective validation of the developed predictive model is recommended.
Objective:
To determine if acid base status predicts which vomiting patients have pyloric stenosis.
Design:
Retrospective chart review.
Setting:
Tertiary paediatric hospital.
Methodology:
We compared the clinical and biochemical parameters of 100 patients with a discharge diagnosis of pyloric stenosis and 84 patients of a similar age who presented to the emergency department with vomiting and who had an acid base determination. Patients were included from January 1995 to January 1997. Clinical correlates consisted of age, duration of vomiting, weight loss, gestation, and family history of pyloric stenosis. Biochemical correlates were pH, bicarbonate, base excess (BE), chloride, potassium, and sodium.
Results:
Independent variables of significance were pH, BE, chloride, bicarbonate, potassium, weight loss (all of which had a P value < 0.0001), and sex (P = 0.006). Each variable was placed in a logistic regression equation with pyloric stenosis being the dominant variable. Variables of significance were pH (P = 0.0001), BE (P = 0.0001), and chloride (P = 0.009). A model for predicting pyloric stenosis using these variables was then created with pH > 7.45, chloride < 98, and BE > +3, with a positive predictive value of 88%.
Conclusion:
Acid base determination is a useful screening tool when considering pyloric stenosis. This model now needs to be validated on a prospective series of patients with vomiting.