A randomized porcine study of the hemodynamic and metabolic effects of combined endovascular occlusion of the vena cava and the aorta in normovolemia and in hemorrhagic shock

The effect of an endovascular Heaney maneuver to achieve total hepatic isolation on survival, hemodynamic stability, retrohepatic bleeding, and collateral flow in a porcine model

PURPOSE

Combining resuscitative endovascular balloon occlusion of the aorta (REBOA) and the inferior vena cava (REBOVC) with open surgery is a new hybrid approach for treating retrohepatic vena caval injuries. We compared endovascular total hepatic isolation with supraceliac REBOA ± suprahepatic REBOVC and no occlusion in experimental retrohepatic vena cava bleeding regarding survival, bleeding volume, hemodynamic stability, and arterial collateral blood flow.

METHODS

Twenty-five anesthetized pigs (n = 6-7/group) were randomized to REBOA; REBOA + REBOVC; REBOA + infra and suprahepatic REBOVC + portal vein occlusion (endovascular Heaney maneuver, four-balloon-occlusion, 4BO) or no occlusion. After balloon inflation, free bleeding was initiated from an open sheath in the retrohepatic vena cava. Bleeding volume, right internal thoracic artery (RITA) blood flow, hemodynamics, and arterial blood variables were measured until death or up to 90 min.

RESULTS

The REBOA group had a longer median survival time (63 min) compared with the 4BO (24 min, P = 0.02) and no occlusion (30 min, P = 0.02) groups, not versus the REBOA + REBOVC group (49 min, P > 0.05). The first 15 min accumulated bleeding was comparable in all groups (P > 0.05); Thereafter, bleeding volume was higher in the REBOA group versus the 4BO group (P < 0.05), not versus the other groups. RITA blood flow and MAP were higher in the REBOA group versus the other groups after 10 min of bleeding (P < 0.05).

CONCLUSIONS

Endovascular Heaney maneuver was not beneficial for survival or hemodynamic stability in this porcine model, whereas supraceliac REBOA was. Anatomical differences in thoracoabdominal collaterals between pigs and humans must be considered when interpreting these results.

Our initial experience of monitoring the autoregulation of cerebral blood flow during cardiopulmonary bypass

BACKGROUND

Cerebral blood flow (CBF) is believed to be relatively constant within an upper and lower blood pressure limit. Different methods are available to monitor CBF autoregulation during surgery. This study aims to critically analyze the application of the cerebral oxygenation index (COx), one of the commonly used techniques, using a reference to data from a series of clinical registrations.

METHOD

CBF was monitored using near-infrared spectroscopy, while cerebral blood pressure was estimated by recordings obtained from either the radial or femoral artery in 10 patients undergoing cardiopulmonary bypass. The association between CBF and blood pressure was calculated as a moving continuous correlation coefficient. A COx index > 0.4 was regarded as a sign of abnormal cerebral autoregulation (CA). Recordings were examined to discuss reliability measures and clinical feasibility of the measurements, followed by interpretation of individual results, identification of possible pitfalls, and suggestions of alternative methods.

RESULTS AND CONCLUSION

Monitoring of CA during cardiopulmonary bypass is intriguing and complex. A series of challenges and limitations should be considered before introducing this method into clinical practice.

A porcine study of ultrasound-guided versus fluoroscopy-guided placement of endovascular balloons in the inferior vena cava (REBOVC) and the aorta (REBOA)

Objectives

In fluoroscopy-free settings, alternative safe and quick methods for placing resuscitative endovascular balloon occlusion of the aorta (REBOA) and resuscitative endovascular balloon occlusion of the inferior vena cava (REBOVC) are needed. Ultrasound is being increasingly used to guide the placement of REBOA in the absence of fluoroscopy. Our hypothesis was that ultrasound could be used to adequately visualize the suprahepatic vena cava and guide REBOVC positioning, without significant time-delay, when compared with fluoroscopic guidance, and compared with the corresponding REBOA placement.

Methods

Nine anesthetized pigs were used to compare ultrasound-guided placement of supraceliac REBOA and suprahepatic REBOVC with corresponding fluoroscopic guidance, in terms of correct placement and speed. Accuracy was controlled by fluoroscopy. Four intervention groups: (1) fluoroscopy REBOA, (2) fluoroscopy REBOVC, (3) ultrasound REBOA and (4) ultrasound REBOVC. The aim was to carry out the four interventions in all animals. Randomization was performed to either fluoroscopic or ultrasound guidance being used first. The time required to position the balloons in the supraceliac aorta or in the suprahepatic inferior vena cava was recorded and compared between the four intervention groups.

Results

Ultrasound-guided REBOA and REBOVC placement was completed in eight animals, respectively. All eight had correctly positioned REBOA and REBOVC on fluoroscopic verification. Fluoroscopy-guided REBOA placement was slightly faster (median 14 s, IQR 13-17 s) than ultrasound-guided REBOA (median 22 s, IQR 21-25 s, p=0.024). The corresponding comparisons of the REBOVC groups were not statistically significant, with fluoroscopy-guided REBOVC taking 19 s, median (IQR 11-22 s) and ultrasound-guided REBOVC taking 28 s, median (IQR 20-34 s, p=0.19).

Conclusion

Ultrasound adequately and quickly guide the placement of supraceliac REBOA and suprahepatic REBOVC in a porcine laboratory model, however, safety issues must be considered before use in trauma patients.

Level of evidence

Prospective, experimental, animal study. Basic science study.

A randomized porcine study of hemorrhagic shock comparing end-tidal carbon dioxide targeted and proximal systolic blood pressure targeted partial resuscitative endovascular balloon occlusion of the aorta in the mitigation of metabolic injury

BACKGROUND

The definition of partial resuscitative endovascular balloon occlusion of the aorta (pREBOA) is not yet determined and clinical markers of the degree of occlusion, metabolic effects and end-organ injury that are clinically monitored in real time are lacking. The aim of the study was to test the hypothesis that end-tidal carbon dioxide (ETCO₂) targeted pREBOA causes less metabolic disturbance compared to proximal systolic blood pressure (SBP) targeted pREBOA in a porcine model of hemorrhagic shock.

MATERIALS AND METHODS

Twenty anesthetized pigs (26-35 kg) were randomized to 45 min of either ETCO₂ targeted pREBOA (pREBOA_ETCO2, ETCO₂ 90-110% of values before start of occlusion, n = 10) or proximal SBP targeted pREBOA (pREBOA_SBP, SBP 80-100 mmHg, n = 10), during controlled grade IV hemorrhagic shock. Autotransfusion and reperfusion over 3 h followed. Hemodynamic and respiratory parameters, blood samples and jejunal specimens were analyzed.

RESULTS

ETCO₂ was significantly higher in the pREBOA_ETCO2 group during the occlusion compared to the pREBOA_SBP group, whereas SBP, femoral arterial mean pressure and abdominal aortic blood flow were similar. During reperfusion, arterial and mesenteric lactate, plasma creatinine and plasma troponin concentrations were higher in the pREBOA_SBP group.

CONCLUSIONS

In a porcine model of hemorrhagic shock, ETCO₂ targeted pREBOA caused less metabolic disturbance and end-organ damage compared to proximal SBP targeted pREBOA, with no disadvantageous hemodynamic impact. End-tidal CO₂ should be investigated in clinical studies as a complementary clinical tool for mitigating ischemic-reperfusion injury when using pREBOA.

Endovascular Balloon Occlusion of the Inferior Vena Cava in Trauma: A Single-Center Case Series

Injury to the inferior vena cava (IVC) can produce bleeding that is difficult to control. Endovascular balloon occlusion provides rapid vascular control without extensive dissection and may be useful in large venous injuries, especially in the juxtarenal IVC. We describe the procedural steps, technical considerations, and clinical scenarios for using the Bridge occlusion balloon (Philips) in IVC trauma. We present a single-center case series of 5 patients in which endovascular balloon occlusion of the IVC was used for hemorrhage control. All 5 patients were men (median age 35, range 22 to 42 years). They all sustained penetrating injuries-4 gunshot wounds and 1 stab wound. Median presenting Shock Index was 0.7 (range 0.5 to 1.5). Median initial lactate was 5.4 mmol/L (range 4.6 to 6.9 mmol/L). There were 2 suprarenal IVC injuries, 2 juxtarenal injuries, and 3 infrarenal injuries. Four patients underwent primary repair of their injury, and one underwent IVC ligation. Four patients had intraoperative Resuscitative Endovascular Balloon Occlusion of the Aorta for inflow control and afterload support. The median number of total blood products transfused during the initial operation was 37 units (range 16 to 77 units). Four patients underwent damage control operations, and one patient had a single definitive operation. Four of the 5 patients (80%) survived to discharge with the lone mortality being due to other injuries. Endovascular balloon occlusion serves as a valuable adjunct in the management of IVC injury and demonstrates the potential of hybrid open-endovascular operative techniques in abdominal vascular trauma.

A clinical study of the hemodynamic and metabolic effects of Zone 3 REBOA for sacral and pelvic tumor resections

Background

Resuscitative endovascular balloon occlusion of the aorta (REBOA) is a key procedure in sacral and pelvic tumor resection that provides hemorrhage control. However, few studies have been performed to capture the effects of REBOA in a nonshock condition and provide a detailed description of the changes occurring with prolonged occlusion time. This study aimed to examine the hemodynamic and metabolic effects of Zone 3 REBOA for sacral and pelvic tumor resections following different periods of REBOA.

Methods

In total, 121 patients who underwent surgical tumor resections of the pelvis and/or the sacrum with the use of aortic balloon occlusion were prospectively enrolled from October 2020 to December 2021. All cases were divided into Group A (occlusion time ≤ 60 min, n = 57) and Group B (occlusion time ≥ 90 min, n = 64). Physiologic parameters were continuously recorded, and laboratory specimens were obtained at regular intervals.

Results

Balloon inflation resulted in a significant increase in SBP from 106 to 120 mmHg and decreased to 96 mmHg immediately following balloon deflation. With the application of REBOA, the median blood loss was only 1200 ml (range, 400–7900). When deflating the REBOA, the arterial pH was lower than baseline (7.36 vs. 7.41, p < 0.01), the arterial lactate concentration increased from 0.9 to 1.4 mmol/L (p < 0.01), serum potassium measurements increased from 3.99 to 4.12 mmol/L, serum calcium measurements decreased from 2.31 to 2.04 mmol/L, and blood creatinine decreased from 64 to 60 µmol/L. The operating time of Group B was longer than that of patients in Group A, and the patients in Group B needed more blood units to be transfused. Although laboratory measurements, including pH, potassium, calcium, and blood creatinine, were at the same level in two groups comparison, the lactate was significantly higher in Group B after deflation (p = 0.01).

Conclusions

The results of this study showed that acceptable hemodynamic and metabolic stability can be attained when the occlusion time of REBOA is more than 90 min, although the long duration of occlusion caused relatively higher lactate levels.