From our study results, we found out that lower pH values and higher lactic acid levels were associated with greater likelihoods of intussusception recurrence. Notably, although the difference in the numerical pH values between the groups was statistically significant, the values for both groups were within the normal range. Thus, the lactic acid level is probably the only clinically meaningful parameter associated with poor outcomes in this setting. Using different lactic acid cutoff levels (≥1.5, ≥2.0, ≥2.5, and ≥3.0 mmol/L), all of the determined negative predictive values were high but the positive predictive values increased as the cutoff values increased. In particular, the positive predictive value for a poor outcome increased from 50% to 88.9% when the cutoff value was increased from ≥2.5 mmol/L to ≥3.0 mmol/L.
In previous studies, patient lactic acid levels were reported to be poor parameters for diagnosing intussusception . Hence, the diagnostic method of choice is ultrasonography . However, a recent study showed that POCUS, performed by emergency physicians, had a similar diagnostic accuracy as radiologist-performed ultrasound . POCUS is widely used in many institutions, inc9luding ours, because it can be promptly performed in the ED.
Based on our study results, lactic acid levels were found to be potential predictors of poor outcomes in pediatric intussusception patients. Although there is no clear definition for an “elevated” lactic acid level, most previous studies report levels of 2.0 or 2.5 mmol/L to indicate elevation . In our study, when a 2.5-mmol/L cutoff was used, 50% of the patients presented poor outcomes; when a 3.0-mmol/L cutoff was used, the positive predictive value increased to 88.9%.
In patients presenting with abdominal pain associated with suspicious mesenteric ischemia, lactic acid level measurements can help guide further diagnostic workups . According to Lange et al., elevated lactic acid levels showed a 96% sensitivity and 38% specificity for indicating mesenteric ischemia . Furthermore, serum lactic acid levels >2 mmol/L may be associated with irreversible intestinal ischemia . In our study, none of the 11 patients who underwent surgical reduction required resection due to bowel ischemia. Xian-Ming et al. concluded that the median time between symptom onset and operative treatment for intussusception was longer in patients who lost intestinal viability (42 h) than for those who did not (19 h) . In our study, the median time between symptom onset and the procedure was 9 h, which was shorter than that reported by Xian-Ming et al, suggesting that intestinal viability had been preserved.
This study has some limitations. The retrospective nature of the study is the first limitation. Secondly, due to our institutional protocol, only VBGA were performed for most of the patients. Thus, we were unable to analyze the presence of leukocytosis or hemoconcentration, which can be observed in patients with acute mesentery ischemia. Nevertheless, elevated lactic acid levels are early signs of tissue hypoxia and can be used as markers for mesenteric ischemia that are more specific than C-reactive protein levels or leukocyte counts [18, 19]. Future research should include a large, prospectively registered population with additional laboratory findings available for analysis. Furthermore, an evaluation of the association between serial lactic acid levels and outcomes is warranted.
To the best of our knowledge, this is the first study to elucidate an association between intussusception outcomes and laboratory data. Although only a few variables were analyzed, we successfully elucidated an association between the increased risk of poor outcome and increased lactic acid levels; theoretically, lactic acid is a marker of tissue hypoperfusion.
In conclusion, elevated lactic acid levels are associated with poor outcomes in pediatric patients with intussusception. In particular, lactic acid levels ≥2.5 mmol/L imply a greater risk for failed nonsurgical reduction or intussusception recurrence, warranting preparedness for alternative treatment strategies.