Effect of Blood Loss and Transfusion Requirements on Clinical Outcomes of Fenestrated-Branched Endovascular Aortic Repair

An In-Vitro Comparison of Steady State Leakage Rates through Introducer Sheaths Used for Fenestrated Endovascular Aortic Aneurysm Repair

BACKGROUND

Fenestrated Endovascular Aneurysm Repair (fEVAR) involves deploying a covered stent into the aorta followed by multiple visceral stents through fenestrations in the main body of graft. The most commonly used large sheaths for cannulation of visceral vessels are the Gore DrySeal Flex, Cook Performer Check-Flo, and Medtronic Sentrant. None of these sheaths were designed for the insertion of multiple sheaths, and so a slow but steady leakage of blood occurs during the procedure. The aim of this paper is to assess in an in vitro setting which large bore sheath has the best valve for use when multiple smaller sheaths are inserted through it.

METHODS

Three large bore introducer sheaths (LBISs) were used for this study, The Gore DrySeal Flex LBIS, Medtronic Sentrant LBIS and Cook Performer Check-Flo LBIS. A test rig was constructed, made of an 18-liter fluid reservoir mounted vertically and receiving a constant supply of water from a domestic water supply which flowed into the reservoir and out of an overflow. The reservoir was connected to the LBIS by a vertical plastic pipe with an internal diameter of 40 mm and an isolation valve. The LBIS was connected to the isolation valve by inserting the LBIS up a flexible silicone tube connected to the isolation valve. The LBIS was subject to a constant column/pressure of water and fluid leakage from the LBIS was collected in a plastic pot/tray placed underneath the LBIS. The leakage rates through each LBIS were determined for the following smaller diameter sheath combinations inserted through the valve, one 6 French Sheath, two 6 French Sheaths, two 6 French Sheaths and one 7 French Sheath. This was done to closely mimic a fEVAR procedure in vitro. The procedure was to insert different sheath combinations through the nonreturn valves in the LBIS and measure the volume of fluid that leaked through the valves. The leaked fluid was weighed, and the weight was converted to volume using the density of water (1 g/ml).

RESULTS

The average (mean) leakage rates for each LBIS and each sheath combination showed that leakage rates when only one sheath was inserted were very low. For all 3 LBIS's tested, the leakage rates increased dramatically when multiple sheaths were inserted. The Medtronic LBIS leaked the most, followed by Cook, followed by Gore. For the Cook LBIS, the leakage rates exhibited with 2 × 6 French sheaths were approx. 106 times greater than those for the Gore LBIS and 5 times greater for the 2 × 6 French +1 × 7 French sheath combination. A similar comparison for the Medtronic LBIS versus the Gore LBIS yields factors of 132 and 8.

CONCLUSIONS

Leakage rates increase significantly when multiple sheaths are inserted and the Gore LBIS demonstrates significantly lower leakage than both the Cook and Medtronic during procedures that require simultaneous, multiple insertions of smaller sheaths. Although the Gore Dryseal has by far the lowest leakage rate when 3 small diameter sheaths are inserted (just under 1 ml/s), depending on the duration of the procedure this could still result in significant blood loss.

The Importance of Cell Saver Usage in Complex Endovascular Repair of Thoraco-Abdominal Aortic Aneurysms

BACKGROUND

The use of the cell saver is well-established in open aneurysm repair; however, its role in endovascular repair is yet to be determined. The aim of this study was to analyze the effects of cell saver usage in patients undergoing complex endovascular procedures.

MATERIALS AND METHODS

Single-center retrospective cohort study, including consecutive patients undergoing fenestrated and/or branched repair for the treatment of thoracoabdominal and complex abdominal aortic aneurysms (CAAAs) between January 2019 and December 2022. The cell saver was a standard part of the intraoperative setup of these procedures, and its use was readily available. The primary endpoint was the percentage of patients, in which autologous blood collected was transfused (cell saver blood transfusion [CSBT]), alongside the useable amount obtained. Secondary endpoints included mean blood loss, postoperative hemoglobin levels, and 30-day mortality.

RESULTS

A total of 170 patients (77.1% male, mean age 71.2 ± 9.2 years) were included, with a median blood loss of 700 mL (interquartile range [IQR] 400-1,200 mL). A total of 96 patients received some kind of blood transfusion (BT) (56.5%): 35 patients were (20.6%) allogenic BT, 31 patients were (18.2%) CSBT only, and 30 patients were (17.6%) a combination of both. In total, 61 patients (35.9% or 63.5% of all patients requiring BTs) received CSBT, with a median useable blood volume of 282 mL (IQR, 194.5-508 mL). Thirty-day mortality was similar in both groups. Although the CSBT group had lower intraoperative hemoglobin values (9.25 ± 1.55 vs. 10.36 ± 1.88 mg/dL; P < 0.001), both groups presented similar postoperative hemoglobin (Hb) levels.

CONCLUSIONS

Blood loss during complex endovascular repair is not insignificant. In this cohort, over 50% of included patients required some kind of BT, 32.3% of which received exclusively CSBT, while 31.3% had supplementary CSBT alongside allogenic BT. This data showcases its potential role in these repairs, paving the way for its standardization in the intraoperative setup of these complex procedures.

Novel method for direct retransfusion reduces blood transfusions in descending and thoracoabdominal aneurysm repair

BACKGROUND

Allogenic blood product usage is associated with worse outcomes in open repair of descending and thoracoabdominal aortic aneurysms. This pilot study evaluated the safety and efficacy of a novel modification of the left heart bypass (LHB) circuit to reduce intraoperative blood transfusions.

METHODS

In modified LHB, pump suckers collected shed blood that was directly retransfused through a femoral vein cannula. In standard LHB, cellsavers were used to collect, wash, and retransfuse shed blood. Consecutive patients undergoing elective surgical descending or thoracoabdominal aneurysm repair using modified (N.=12) or standard (N.=21) LHB were compared. Intraoperative blood product use was the primary outcome. Hypotensive episodes, lactate levels, and adverse events (early mortality, spinal cord injury, renal and respiratory insufficiency) were secondary outcomes.

RESULTS

Groups were comparable regarding pre- and intraoperative variables. No perfusion-related adverse events occurred. With modified LHB, intraoperative blood product use was significantly reduced: packed red blood cells by 60% from 10 to 4 units (P=0.002), fresh frozen plasma by 70% from 17 to 5 units (P<0.001) as well as retransfused cellsaver volume by 75%, from 4500 mL to 1110 mL (P<0.001). Hemodynamic instability occurred in 1 (8.3%) vs. 6 (29%), P=0.22 and overall lactate levels were significantly reduced (P=0.045) with modified LHB. Adverse events combined occurred in 1/12 vs. (P=0.022).

CONCLUSIONS

The novel modified LHB with direct retransfusion was safe and associated with significantly reduced intraoperative blood product use, reduced lactate production and improved clinical outcomes as compared to standard LHB and could represent an important clinical improvement.

Effects of fluids vs. vasopressors on spinal cord microperfusion in hemorrhagic shock induced ischemia/reperfusion

OBJECTIVE

Spinal cord injury induced by ischemia/reperfusion is a devastating complication of aortic repair. Despite developments for prevention and treatment of spinal cord injury, incidence is still considerably high majorly impacting patient outcome. Microcirculation is paramount for tissue perfusion and oxygen supply and often dissociated from macrohemodynamic parameters used to guide resuscitation. Effects of fluids vs. vasopressors in the setting of hemodynamic resuscitation on spinal cord microperfusion are unknown. Aim of this study was to compare the effects of vasopressor and fluid resuscitation on spinal cord microperfusion in a translational acute pig model of hemorrhagic shock induced ischemia/reperfusion injury.

METHODS

We designed this study as prospective randomized explorative large animal study. We induced hemorrhagic shock in 20 pigs as a model of global ischemia/reperfusion injury. We randomized animals to receive either fluid or vasopressor resuscitation. We measured spinal cord microperfusion using fluorescent microspheres as well as laser-Doppler probes. We monitored and analyzed macrohemodynamic parameters and cerebrospinal fluid pressure.

RESULTS

Spinal cord microperfusion decreased following hemorrhagic shock induced ischemia/reperfusion injury. Both fluids and vasopressors sufficiently restored spinal cord microperfusion. There were no important changes between groups (percentage changes compared to baseline: fluids 14.0 (0.31-27.6) vs. vasopressors 24.3 (8.12-40.4), p = .340). However, cerebrospinal fluid pressure was higher in animals receiving fluid resuscitation (percentage changes compared to baseline: fluids 27.7 (12.6-42.8) vs. vasopressors -5.56 ((-19.8)-8.72), p = .003). Microcirculatory resuscitation was in line with improvements of macrohemodynamic parameters.

CONCLUSIONS

Both, fluids and vasopressors, equally restored spinal cord microperfusion in a porcine acute model of hemorrhagic shock induced ischemia/reperfusion injury. However, significant differences in cerebrospinal fluid pressure following resuscitation were present. Future studies should evaluate these effects in perfusion disruption induced ischemia/reperfusion conditions of microcirculatory deterioration.

Peri-Operative Management of Patients Undergoing Fenestrated-Branched Endovascular Repair for Juxtarenal, Pararenal and Thoracoabdominal Aortic Aneurysms: Preventing, Recognizing and Treating Complications to Improve Clinical Outcomes

The advent and refinement of complex endovascular techniques in the last two decades has revolutionized the field of vascular surgery. This has allowed an effective minimally invasive treatment of extensive disease involving the pararenal and the thoracoabdominal aorta. Fenestrated-branched EVAR (F/BEVAR) now represents a feasible technical solution to address these complex diseases, moving the proximal sealing zone above the renal-visceral vessels take-off and preserving their patency. The aim of this paper was to provide a narrative review on the peri-operative management of patients undergoing F/BEVAR procedures for juxtarenal abdominal aortic aneurysm (JAAA), pararenal abdominal aortic aneurysm (PRAA) or thoracoabdominal aortic aneurism (TAAA). It will focus on how to prevent, diagnose, and manage the complications ensuing from these complex interventions, in order to improve clinical outcomes. Indeed, F/BEVAR remains a technically, physiologically, and mentally demanding procedure. Intraoperative adverse events often require prolonged or additional procedures and complications may significantly impact a patient's quality of life, health status, and overall cost of care. The presence of standardized preoperative, perioperative, and postoperative pathways of care, together with surgeons and teams with significant experience in aortic surgery, should be considered as crucial points to improve clinical outcomes. Aggressive prevention, prompt diagnosis and timely rescue of any major adverse events following the procedure remain paramount clinical needs.

Effect of Remote Ischemic Preconditioning on the Incidence of Contrast Induced Nephropathy in Patients Undergoing Evar (Ripc-Evar Study)

INTRODUCTION

Contrast induced nephropathy (CIN) is a major inconvenience in the use of iodinated contrast media (ICM) and it is associated with a significant increase in morbidity and mortality and cost of hospitalization. Remote ischemic preconditioning (RIPC) is a non-invasive and cost-effective tissue protection technique that has showed beneficial in decreasing renal insult in patients receiving intravascular contrast.

AIM

The primary outcome of this study is to evaluate the impact of RIPC on the incidence of CIN in patients undergoing endovascular aneurysm repair.

MATERIAL AND METHODS

Patients suffering from aortic aneurysm were recruited prior to the administration of iodinated contrast media. Randomization was used to assign patients into the control/RIPC groups. Biochemical parameters determined renal function before and after surgery in immediate (24-72 hours) and at 30 days' follow-up.

RESULTS

Of the 120 patients included in the study, 98,3% were male. Mean age was 73 years (range 56-87). Diabetes and chronic renal failure (considering eGFR<60) was present prior to administration of ICM in 29,16% and 38,33% respectively. RIPC was applied in 50% (n=60) of the patients. A total of 24,17% developed CIN regardless of fluid therapy, RIPC and other protective strategies. RIPC did not influence outcome in terms of incidence on CIN, serum creatinine, urea, estimated glomerular filtration (eGFR) or microalbuminuria in immediate postoperative period. However, the group of RIPC patients showed a statistically significant benefit in renal function in terms of serum creatinine (1,46 ± 0,3 vs 1,03 ± 0,5; p<0,001), urea (61,06 ± 27,5mg/dl vs 43,78 ± 12,9mg/dl; p=0,003) and an increase in eGFR (56,37 ± 23,4ml/min/1.73m²vs 72,85 ± 17,7ml/min/1.73m²; p=0,004) at 30 days follow-up.

CONCLUSIONS

RIPC seems to be a reasonable, effective and low-cost technique to alleviate effects of ICM on the renal parenchyma in EVAR procedures during short-term postoperative period.