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Fewer REBOA complications with smaller devices and partial occlusion: evidence from a multicentre registry in Japan
  1. Yosuke Matsumura1,
  2. Junichi Matsumoto2,
  3. Hiroshi Kondo3,
  4. Koji Idoguchi4,
  5. Tokiya Ishida5,
  6. Yuri Kon6,
  7. Keisuke Tomita7,
  8. Kenichiro Ishida8,
  9. Tomoya Hirose9,
  10. Kensuke Umakoshi10,
  11. Tomohiro Funabiki11
  12. DIRECT-IABO Investigators
  1. 1 R Adams Cowley Shock Trauma Center, University of Maryland, Baltimore, USA
  2. 2 Department of Emergency and Critical Care Medicine, St Marianna University School of Medicine, Kawasaki, Japan
  3. 3 Department of Radiology, Teikyo University School of Medicine, Itabashi-ku, Japan
  4. 4 Senshu Trauma and Critical Care Center, Rinku General Medical Center, Izumisano, Japan
  5. 5 Emergency and Critical Care Center, Ohta Nishinouchi Hospital, Koriyama, Japan
  6. 6 Emergency and Critical Care Center, Hachinohe City Hospital, Hachinohe, Japan
  7. 7 Department of Emergency and Critical Care Medicine, Chiba University Graduate School of Medicine, Chiba, Japan
  8. 8 Department of Acute Medicine and Critical Care Medical Center, Osaka National Hospital, National Hospital Organization, Osaka, Japan
  9. 9 Department of Traumatology and Acute Critical Medicine, Osaka University Graduate School of Medicine, Suita, Japan
  10. 10 Department of Emergency and Critical Care Medicine, Ehime University Graduate School of Medicine, Toon, Japan
  11. 11 Emergency and Critical Care Center, Saiseikai Yokohamashi Tobu Hospital, Yokohama, Japan
  1. Correspondence to Dr Yosuke Matsumura, R Adams Cowley Shock Trauma Center, University of Maryland, 22 S Greene St, Baltimore, MD 21201, USA; yousuke.jpn4035{at}


Background Resuscitative endovascular balloon occlusion of the aorta (REBOA) performed by emergency physicians has been gaining acceptance as a less invasive technique than resuscitative thoracotomy.

Objective To evaluate access-related complications and duration of occlusions during REBOA.

Methods Patients with haemorrhagic shock requiring REBOA, from 18 hospitals in Japan, included in the DIRECT-IABO Registry were studied. REBOA-related characteristics were compared between non-survivors and survivors at 24 hours. 24-Hour survivors were categorised into groups with small (≤8 Fr), large (≥9 Fr) or unusual sheaths (oversized or multiple) to assess the relationship between the sheath size and complications. Haemodynamic response, occlusion duration and outcomes were compared between groups with partial and complete REBOA.

Results Between August 2011 and December 2015, 142 adults undergoing REBOA were analysed. REBOA procedures were predominantly (94%) performed by emergency medicine (EM) physicians. The median duration of the small sheath (n=53) was 19 hours compared with 7.5 hours for the larger sheaths (P=0.025). Smaller sheaths were more likely to be removed using external manual compression (96% vs 45%, P<0.001). One case of a common femoral artery thrombus (large group) and two cases of amputation (unusual group) were identified. Partial REBOA was carried out in more cases (n=78) and resulted in a better haemodynamic response than complete REBOA (improvement in haemodynamics, 92% vs 70%, P=0.004; achievement of stability, 78% vs 51%, P=0.007) and allowed longer occlusion duration (median 58 vs 33 min, P=0.041). No statistically significant difference in 24-hour or 30-day survival was found between partial and complete REBOA.

Conclusion In Japan, EM physicians undertake the majority of REBOA procedures. Smaller sheaths appear to have fewer complications despite relatively prolonged placement and require external compression on removal. Although REBOA is a rarely performed procedure, partial REBOA, which may extend the occlusion duration without a reduction in survival, is used more commonly in Japan.

  • resuscitative endovascular balloon occlusion of the aorta
  • hemorrhagic shock
  • complication
  • partial occlusion
  • arterial access
  • sheath
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Key messages

What is already known on this subject?

  • Resuscitative endovascular balloon occlusion of the aorta (REBOA), performed by emergency physicians, is gaining acceptance as an alternative to resuscitative thoracotomy. Clinical studies on REBOA are limited owing to small numbers.

What this study adds

  • Using a database of REBOA recipients from 18 hospitals in Japan, we found that partial REBOA was more commonly performed, allowing a longer duration of occlusion. Smaller sheaths were associated with fewer complications. Emergency physicians performed the majority of the procedures.


Haemorrhagic shock is the primary cause of potentially preventable deaths worldwide.1 2 Resuscitative thoracotomy and aortic cross-clamping are recommended measures for only a limited group of patients with haemodynamically unstable, non-compressible torso trauma as survival rates are low.3 Recently, resuscitative endovascular balloon occlusion of the aorta (REBOA) has gained greater acceptance,4 as an alternative, minimally invasive stabilisation and resuscitation procedure.5–7

Deployment of REBOA in trauma care is governed by location, the availability of surgery and/or interventional radiology (IR), and blood transfusion. Although some studies have identified its potential pitfalls,8 9 earlier reports have shown improved survival rates in comparison with resuscitative thoracotomy.10 However, clinical studies on REBOA are still relatively new and the number of cases is often small.5 6 11 More extensive analysis is necessary to demonstrate its safety and efficacy.

In Japan, there have been no multi-institutional or nationwide reports on REBOA. However, the Intra-Aortic Balloon Occlusion (IABO) Registry, maintained by the Japanese Society of Diagnostic and Interventional Radiology in Emergency, Critical Care and Trauma (DIRECT), has collected clinical observational data in Japan. The objective of this study was to evaluate outcomes, access-related complications and duration of occlusion in patients receiving REBOA.

Materials and methods

Study setting

The DIRECT-IABO Registry is maintained by the Japanese Society of DIRECT academic committee and is approved by the Planning for the Future Commission of the Japanese Association of Surgery of Trauma. All the participating hospitals obtained approval from the local institutional review boards before the registration of patients’ data. Patients who had undergone REBOA deployment for refractory haemorrhagic shock at 18 hospitals in Japan were registered. On detection of severe haemorrhagic shock, initial assessment and resuscitation were performed by either emergency medicine (EM) physicians or acute care surgeons. Definitive haemostasis was achieved through operative intervention, angioembolisation or other procedures.

Procedure and devices for REBOA

The arterial sheath was placed in the common femoral artery (CFA) either by blind puncture, ultrasound (US)-guided puncture or cut down. In some cases, a small (4 or 5 Fr) femoral arterial sheath or standard arterial line was upsized. The commercially available REBOA catheters in Japan are 7 Fr (Rescue Balloon, Tokai Medical Products, Aichi, Japan), 10 Fr (IABO Block Balloon, Senko Medical Instrument Mfg. Co, Ltd, Tokyo, Japan), 12 Fr (Lock Balloon, Tokai Medical Products) and 14 Fr (Equaliser Occlusion Balloon Catheter, Boston Scientific, Massachusetts, USA) for adult patients. Imaging is recommended to confirm that the guidewire is in the aorta. The balloon catheter is then inserted over the guidewire and inflated until appropriate resistance is met.

Data collection

We retrieved all cases of REBOA from the registry entered between August 2011 and December 2015. Data on patient characteristics, bleeding site, systolic blood pressure (SBP) during REBOA insertion (‘pre-occlusion SBP’) and 5 min after balloon inflation (‘post-occlusion SBP’), transfusion requirements during the first 24 hours, survival outcomes, and laboratory data were recorded. Haemodynamic improvement and the achievement of stability (defined as SBP consistently >90 mm Hg12) were also recorded. In Japan, blood products are approximately one-half of the volume of the products provided in Europe or the USA, with one unit of a blood product in Japan consisting of 200 mL donor blood. We used a method previously described to estimate the volume of blood products given by the reported units.13 14

Data on the REBOA device, procedure and operator characteristics were obtained from all the hospitals in the database. The sheath size, location of REBOA placement, arterial access method and imaging confirmation of the guidewire in the aorta were recorded. Sheath sizes were defined as ‘small sheath group (≤8 Fr)’ and ‘large sheath group (≥9 Fr)’. Cases in which additional sheaths were placed in the ipsilateral CFA or in which sheaths were upsized for further endovascular treatments were categorised as the ‘unusual group.’ Further endovascular treatments included veno-arterial extracorporeal membranous oxygenation (VA-ECMO) or stent graft placement. The level of balloon deployment was defined according to a previous study: zone I (between the left subclavian artery and coeliac artery), zone II (between the coeliac artery and lowest renal artery) or zone III (between the lowest renal artery and aortic bifurcation).4

After confirmation of haemodynamic stabilisation, physicians partially deflated the balloon in small steps of 1–3 mL, aiming to keep the SBP at >90 mm Hg, to allow distal perfusion (partial REBOA (P-REBOA)).14 For optional monitoring, the distal arterial pressure was measured to evaluate the visceral organ and lower limb perfusion when the contralateral femoral arterial line was placed. The second sheath was used simply as an arterial line or could be used as access for interventional radiology. The balloon was locked once the target SBP was achieved. If patients deteriorated suddenly, balloon re-inflation was required until complete occlusion (complete REBOA (C-REBOA)) was achieved. Aortic occlusion times were reported as ‘total duration of complete occlusion’, representing the total time of any aortic occlusion (the sum of the duration of C-REBOA and P-REBOA) and ‘duration of partial occlusion’, representing the total time the balloon was partially deflated.

No screening protocols were in place to identify complications in the participating hospitals. All patients returning for follow-up examination were examined for possible complications and were further investigated when a clinical suspicion arose.14


We compared survivors and non-survivors at 24 hours for access type and REBOA-related data, including the bleeding site, operator specialty and experience, location of REBOA deployment, access method, imaging used to confirm the guidewire, aortic level of deployment and duration of aortic occlusion. In patients surviving longer than 24 hours, we compared the groups with different sheath sizes for complications, considering access method, placement duration and method of sheath removal. Finally, the duration of aortic occlusion, haemodynamic response and 24-hour and 30-day survival were compared for C-REBOA and P-REBOA.

Because all the data sources were observational, this study cannot exclude the risk of bias of eligibility criteria and the flawed measurement of both exposure and outcomes. The study size was based on the cases available in the registry from the participating hospitals during the study period.

Statistical analysis

Data are presented as median (IQR), absolute numbers and percentages. Between-group differences were detected using the Mann–Whitney U test. The Wilcoxon signed-rank test was used for paired continuous data and Fisher’s exact test or χ2 test for categorical data. The cases for which data on the occlusion duration were missing were excluded from the comparison of the C-REBOA and P-REBOA groups. All levels of significance are reported at the level α=0.05 using a two-tailed test. Analyses were performed using the IBM SPSS version 22 (IBM Corp, Armonk, New York, USA).


Patient and REBOA characteristics

Of the 144 REBOA patients in the registry, two aged <18 years were excluded, and the remaining 142 cases were then analysed in this study (figure 1). Patients were predominantly male (64%) and the median (IQR) body mass index (BMI) was 23 (20–25) kg/m2. The most common haemorrhage sites were the abdomen (54%), pelvic (50%), chest (21%) and retroperitoneal (13%) regions. The median pre-occlusion SBP was 60 (40–81) mm Hg, which then improved to 110 (91–131) mm Hg after aortic occlusion. Improvement in haemodynamics with REBOA was seen in 82% of cases and in 70%, stability was achieved. Eighty-one patients (57%) survived beyond 24 hours and 62 patients (44%) survived over 30 days (table 1).

Figure 1

Flowchart of the study. One hundred and forty-four patients undergoing resuscitative endovascular balloon occlusion of the aorta (REBOA) were enrolled; two patients aged <18 years were excluded. Results for the 61 non-survivors and 81 survivors at 24 hours were analysed. Among the 81 survivors, two patients required a larger cannula and one patient had multiple sheaths in the ipsilateral common femoral artery. The groups with a small sheath (n=53), a large sheath (n=25) and unusual requirements (n=3) were compared. The complete REBOA (C-REBOA; n=37) and partial REBOA (P-REBOA; n=78) groups were compared and the results analysed after exclusion of patients with an an incomplete record of occlusion time.

Table 1

Baseline characteristics and clinical outcomes

Twenty-eight patients (20%) required cardiopulmonary resuscitation at REBOA insertion. Of these, nine patients (32%) survived beyond 24 hours and 4 (14%) survived beyond 30 days.

The sheath sizes used were 7 Fr (62%), 8 Fr, (1.4%), 10 Fr (27%), 12 Fr (5.6%) and 14 Fr (3.5%). REBOA was performed by either EM physicians, EM physicians with cross-training in interventional radiology (EM-IRs), interventional radiologists (IRs) or others. Of the 142 REBOA procedures, 44% were conducted by EM physicians, 50% by EM-IRs and 4.2% by IRs. Most (65%)procedures were performed by attending physicians (84%). REBOA was most commonly initiated in the emergency department (ED), followed by the angiography suite (18%) and the operating room (7.7%). Of the 11 patients for whom REBOA was started in the operating room, 10 survived beyond 24 hours and one patient with severe liver injury died within 24 hours. Nine patients had abdominal bleeding and none had chest bleeding (table 2).

Table 2

Access and REBOA information in the studied population

The most commonly reported access for REBOA was percutaneous without imaging (92%), followed by US-guided (2.8%) and femoral cut down (2.1%). Imaging was used in 77% of cases to confirm guidewire location within the aorta (15% US, 29% plain X-ray film, 32% fluoroscopy). Initial deployment was achieved at zone I in 95% of cases, balloon rupture occurred in 0.7% and migration was encountered after balloon inflation in 2.1%. Aortic occlusion times were accurately recorded in 115 patients; of these, partial occlusion was performed in 68%.

Factors associated with 24-hour survival

The non-survivors presented with significantly more chest bleeding than survivors (36% vs 9.9%) and less abdominal bleeding (39% vs 65%) (table 2). The operating room was more commonly deployed for survivors (non-survivors vs survivors, 1.6% vs 12%). The total duration of occlusion was significantly shorter in the survivors group (non-survivors vs survivors, 78 vs 34 min). The duration of partial occlusion and probability of partial occlusion were similar.

Sheath sizes and complications

Among the 81 survivors at 24 hours, 53 had a small femoral sheath placed for 19 (11–27) hours while in 25 patients, a larger sheath was placed for 7.5 (3.5–18) hours (P=0.025). Two patients were upsized to a larger sheath; 9 Fr sheath for the stent graft and 15 Fr ECMO returning cannula. A 5 Fr sheath was added to the 7 Fr REBOA sheath for the IR procedure in the ipsilateral CFA in one case. In the remaining three patients (unusual group), either oversized sheaths (n=2) or multiple sheaths (n=1) were placed (figure 1, table 3).

Table 3

Procedures and complications among groups according to sheath size in 24-hour survivors

Percutaneous blind puncture was dominant in all the groups, large, small and unusual (85%, 96% and 100%, respectively). (table 3). On sheath removal, external manual compression was selected in 96% of the cases in the small group and in 45% of the cases in the large group (P<0.001), with the others receiving surgical repair. For sheath-related complications, dissection (n=1, 1.9%) and massive hematoma (n=1, 1.9%) were observed in the small group, but no additional treatment was required. Common femoral artery stenosis resulting from thrombus formation was identified in one patient (4.0%) in the large sheath group while two cases (67%) of lower limb ischemia followed by fasciotomy and amputation were identified in the unusual sheath group (upsized to 15 Fr ECMO returning cannula, 5 Fr and 7 Fr sheaths in a common femoral artery).

Complete versus partial REBOA

Thirty-seven patients had C-REBOA and 78 P-REBOA (Figure 1). The post-occlusion SBP was significantly higher (P=0.009) in the P-REBOA group despite a similar pre-occlusion SBP. Improvement in haemodynamics (C-REBOA vs P-REBOA, 70% vs 92%; P=0.004) and achievement of stability (C-REBOA vs P-REBOA, 51% vs 78%; P=0.007) were also more frequently observed in the P-REBOA. The duration of total occlusion was significantly longer in the P-REBOA group (C-REBOA vs P-REBOA, 33 vs 58 min; P=0.041). No difference in the 24-hour and 30- day survival was found between the two methods (table 4).

Table 4

Characteristics and outcomes of complete and partial REBOA


This study, based on a registry of all patients receiving REBOA in Japan between 2011 and 2015, suggests that, although REBOA is performed infrequently, P-REBOA is more common and most of the sheaths placed are small. In North America and Europe, REBOA procedures are performed with larger 11 to 14 Fr sheaths. Until recently, 10 Fr sheath-compatible catheters were widely used in Japan. However, since 2013, a surge in the popularity of smaller 7 Fr compatible balloon catheters has been observed. It was not until 2016 that a newly developed 7 Fr sheath-compatible catheter was made commercially available in the USA (ER-REBOA catheter, Prytime Medical, Boerne, Texas, USA).

In the small group, the arterial sheath was placed for a significantly longer time and it was more often removed with external manual compression. These study findings corroborate findings from previous studies reporting the safety and feasibility of smaller arterial sheaths.14 Although no complications that required surgical or endovascular treatments arose in the small group, the large sheath group had one case requiring percutaneous transluminal angioplasty and two separate cases of lower limb amputation (female, BMI, 23 kg/m2; 15 Fr ECMO returning cannula, and male, BMI, 31; 5 Fr and 7 Fr sheaths in ipsilateral CFA). Although a small physical build seems to contribute to the risk of limb ischaemia, it has been noticed in a patient with a large physique too. Reported cases of amputation after 10 Fr sheath placement6 suggest that smaller sheaths might improve distal arterial flow and hence prevent such sequelae.

In this study, the P-REBOA group showed a better haemodynamic response than the C-REBOA group; this could be attributed to patients’ poor haemodynamic instability preventing safe P-REBOA deflation. The P-REBOA group also demonstrated significantly longer duration of balloon occlusion but the groups had similar survival at 24 hours or 30 days. These findings are in line with results from previous reports,15 suggesting that P-REBOA may extend the golden time of REBOA. Although P-REBOA is commonly used, it was not selected in all the cases, perhaps owing to individual patient profiles and a lack of common protocols and agreement as to when and how P-REBOA should be performed. Further research needs to be directed towards this technique.

Despite the suggested algorithm,15 the precise indications for REBOA remain unclear. In our patients, chest bleeding was more common in the 24-hour non-survivors group. Understandably, an aortic injury detected on chest X-ray examination is a contraindication to REBOA, but chest bleeding sources are often difficult to identify initially. REBOA may exacerbate proximal thoracic arterial haemorrhage and does not work in cases of pulmonary haemorrhage. Nevertheless, REBOA could still be effective in patients with polytrauma, such as mild chest and severe abdominal injury, and to this end, appropriate patient selection is critical.

The REBOA procedures were predominantly performed by EM physicians. REBOA has been carried out since the early 1990s in Japan and therefore, most EM physicians are familiar with the techniques.9 Compared with North America, where REBOA is performed primarily by surgeons,12 EM physicians undertake the majority of REBOA procedures in Japan, with comparable complication rates.14 Nevertheless, REBOA is not a routine procedure and complications may be associated with insufficient skill and experience. Our entire dataset consisted of only 142 cases, across 18 hospitals, which indicates that individual EM physicians may not have sufficient experience with REBOA procedures. In addition, there is no nationally standardised certification and therefore, endovascular workshops15 16 were conducted to provide qualifying skills. The Japanese Society of DIRECT (established in 2011)9 has been conducting workshops since 2013 to promote safe insertion procedures in the ED without fluoroscopy for EM physicians, acute care surgeons and IRs.

While the ED was the most common location for REBOA deployment, it was initiated in the operating room in 11 patients. These results demonstrate the potential benefits of REBOA during abdominal surgery, in cases in which REBOA was not initially required in the ED.

This study has several limitations. First, this is a retrospective observational study. Second, the Japanese physique, the medical training and the specific instruments used may limit generalisation of the results to other countries. Third, the small number of included cases can make data interpretation and therefore, research into REBOA, difficult. Finally, data were missing from our observational study. Despite these limitations, our results suggest that smaller sheaths and partial occlusion are useful. The DIRECT-IABO registry is still new and further development and gathering of additional information could be useful. Sharing the data of our registry with information from other international databases would improve generalisability.12


EM physicians are undertaking the majority of REBOA procedures in Japan. Smaller sheaths might be associated with fewer complications and could be removed with manual external compression even after prolonged sheath placement. Although C-REBOA is rarely performed, P-REBOA is used more commonly in Japan and may prolong balloon occlusion time without a negative effect on survival. Further evaluation can be expected with the maturation of the DIRECT-IABO registry.


We thank all the investigators of the DIRECT-IABO Registry. Osaka City University Hospital (Naohiro Hagawa, MD); Ohta Nishinouchi Hospital (Tokiya Ishida, MD); National Hospital Organization Osaka National Hospital (Kenichiro Ishida, MD); Nippon Medical School Musashikosugi Hospital (Eiji Yamamura, MD); Ehime University Hospital (Kensuke Umakoshi, MD); Saga University Hospital (Kosuke Chiris Yamada, MD); Tokyobay UrayasuIchikawa Medical Center (Yosuke Homma, MD); Osaka University Hospital (Tomoya Hirose, MD); Kouseiren Takaoka Hospital (Mahiro Fujii, MD); Asahi General Hospital (Chikao Ito, MD); Teikyo University Hospital (Takahiro Yamamoto, MD);Saiseikai Yokohamashi Tobu Hospital (Tomohiko Orita, MD);St. Marianna University School of Medicine Hospital (Junichi Matsumoto, MD); Osaka Prefcture Senshu Critical Care Medical Center (Koji Idoguchi, MD); Hachinohe City Hospital (Yuri Kon, MD); Chiba University Hospital (Keisuke Tomita, MD); Yokohama Rosai Hospital (Takafumi Shinjo, MD) and Toho University Omori Medical Center (Yukitoshi Toyoda, MD).


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  • Contributors YM contributed to study conception and design, analysis and interpretation of data, statistical analysis, drafting of the manuscript. JM, HK, KId and TF contributed to critical revision of the manuscript for important intellectual content, and provided intellectual input to the research and manuscript. TI, YK, KT, KIs, TH and KU contributed to acquisition of data, and provided intellectual input to the research and manuscript. All authors read and approved the manuscript.

  • Competing interests YM is a clinical advisory member of Tokai Medical Products.

  • Ethics approval Japanese Association of Surgery of Trauma ethics committee, Chiba University Graduate School of Medicine and institutional review board in all participating hospitals.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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