Discussion
This is the first study to specifically address gastrointestinal function after REBOA placement in clinical practice. In our single-center retrospective cohort study with propensity score matching analysis conducted at a Japanese urban trauma center, REBOA use was associated with FI and a longer time to achieve feeding goals.
Patients who underwent REBOA placement experienced prolonged durations of mechanical ventilation and longer ICU stays. No statistically significant differences in the incidence of pneumonia and AKI between the REBOA and non-REBOA group were observed. Although previous large-scale multi-institutional studies on REBOA have been conducted, our study contributes to the existing literature by providing a detailed exploration of the impact on gastrointestinal function. The development of FI is a critical concern, particularly in relation to timely initiation of EN, which offers numerous benefits for critically ill patients.
FI is a frequently observed complication in severe trauma patients. Although the definition of FI varies across studies, recent research has consistently shown a high incidence of FI ranging from 33% to 50% in this patient population.6 7 19 The etiology of FI in trauma patients is likely multifactorial. Previous studies have highlighted the associations between gastrointestinal disorders and factors such as high ISS, head injury, and abdominal trauma.7 20 In our study, the incidence of FI and ileus was found to be 52.3% and 18.2%, respectively, relatively high compared with previous reports. This elevated FI incidence can be attributed not only to the effects of REBOA but also to our patient population, which consisted of individuals with higher ISS and abdominal trauma. Furthermore, it is important to note that opioids, which were administered to all patients in our study, can impair gastrointestinal motility in critically ill patients.21
The present study demonstrated that REBOA was a risk factor of FI. FI is known to be associated with an increased risk of several complications, higher hospitalization costs, and prolonged hospital stays.22 23 Furthermore, FI can contribute to the development of multiple organ failure in severe trauma patients.24 A large study utilizing the US nationwide trauma registry reported that REBOA was associated with higher rates of AKI, although there was no significant difference in other complications.25 In our study, we observed numerically higher rates of pneumonia, AKI, and longer hospital stays in patients who underwent REBOA placement compared with those without REBOA, although these differences did not reach statistical significance. Further studies with large sample size are needed to comprehensively explore the relationship between REBOA and complications or length of hospital stays.
REBOA has the potential to induce FI in trauma patients. First, REBOA can exacerbate intestinal ischemia in addition to hemorrhagic shock. Animal studies show that the mesenteric artery blood flow is significantly reduced during inflation26 and histological evidence of intestinal mucosal damage has been observed.5 Second, REBOA may promote gut edema. A study in an animal model of hemorrhagic shock reported a significant increase in fluid resuscitation volume after 90 minutes of REBOA.27 Considering the inflammatory cytokine response and the potential for ischemic/reperfusion injury, it is likely that vascular permeability is increased in the intestine, leading to resuscitation-induced gut edema and subsequent intestinal dysfunction.28 Intra-abdominal hypertension should be carefully monitored during REBOA. In our study, several gastrointestinal symptoms besides FI were more common in patients with REBOA and there was one case of mesenteric ischemia necessitating bowel resection. Therefore, trauma surgeons should exercise caution in the deployment of REBOA, aiming to minimize the risk of ischemic complications. Appropriate partial REBOA techniques may also prove beneficial in mitigating the occurrence of ischemic complications.
Here, CRP was used as an indicator of inflammatory response and did not show a significant increase in patients with REBOA. This may be because CRP is a less sensitive marker of inflammation compared with the direct measurement of cytokines. CRP production in the liver is regulated by the inflammatory cytokines interleukin 6 (IL-6) and has a direct correlation with IL-6 levels.29 30 Unfortunately, we did not have data on inflammatory cytokine levels. Another reason for this result could be that the cytokine levels induced by REBOA were relatively low compared with the excessive cytokine levels associated with severe traumatic insult.
The present study has several limitations. The small sample size and single-center retrospective design are the primary limitations. Although higher rates of gastrointestinal symptoms, AKI, and pneumonia were observed in the REBOA group, these differences were not statistically significant. A large nationwide study conducted in the USA reported similar findings, showing a higher rate of AKI in the REBOA group.25 A post hoc power calculation revealed a power of 25% to detect differences in AKI and pneumonia between groups in our study. There is the possibility of underestimating the effect sizes of the observed differences between groups. Multi-institutional trials are necessary to confirm these findings. Second, we conducted propensity matching by using data to minimize selection bias. However, unmeasured confounding factors must remain. The selected variables only would be difficult to balance the characteristics of the two groups divided by whether or not REBOA was performed, as in a randomized controlled trial. Also, the upper limit of 0.2 for the absolute standardized mean difference is large. Although the limit of 0.1 is more appropriate, it does entail a trade-off as it restricts the number of eligible subjects. Third, this study did not consider REBOA balloon size and inflation duration, which could have a significant impact on intestinal mucosal damage. This is due to incomplete records regarding the REBOA balloon size and inflation time. Fourth, FI was defined by the study authors. The definition of FI should affect the result significantly. There is no universally accepted definition of FI. Instead, in this study, it has been defined using references from various studies.16 Finally, the potential presence of survivorship bias may be caused because this study primarily focuses on patients who survived at least 4 days after the injury. This bias may result in an underestimation of the FI, as we may be analyzing a population that is inherently more resilient or responsive to interventions in terms of avoiding severe complications. These limitations highlight the need for large-scale studies that take into account additional factors to provide a more comprehensive understanding of the effects and potential complications associated with REBOA.