Coagulation Disorders and Blood Product Use in Patients Undergoing Thoracoabdominal Aortic Aneurysm Repair

Critical Care of the Vascular Surgery Patient

Patients that require major vascular surgery suffer from widespread atherosclerosis and have multiple comorbidities that place them at increased risk for postoperative complications and require admission to the intensive care unit (ICU). Postoperative critical care of these patients is focused on hemodynamic optimization, and early identification and management of complications to improve outcomes.

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.

[Comparison of the outcomes between open and hybrid approaches in the treatment of thoracoabdominal aortic aneurysms repair]

OBJECTIVE

Thoracoabdominal aortic aneurysm is one of the most challenging aortic diseases. Open surgical repair remains constrained with considerable perioperative morbidity and mortality. The emergence of a hybrid approach utilizing visceral debranching with endovascular aneurysm repair has brought an alternative for high-risk patients. This study aimed to compare the short- and long-term outcomes between hybrid and open repairs in the treatment of thoracoabdominal aortic aneurysms.

METHODS

In this retrospectively observational study, patients with thoracoabdominal aortic aneurysm treated in a single center between January 2008 and December 2019 were reviewed, of whom 11 patients with hybrid repair, and 18 patients with open repair were identified. Demographic characteristic, operative data, perioperative morbidity and mortality, freedom from reintervention, and long-term survival were compared between the two groups.

RESULTS

In the hybrid repair group, the patients with dissection aneurysm, preoperative combined renal insufficiency, and American Society of Anesthesiologists (ASA) score of 3 or more were significantly overwhelming than in the open repair group. The operation time of debranching hybrid repair was (445±85) min, and the intraoperative blood loss was (955±599) mL. There were 2 cases of complications in the early 30 days after surgery, without paraplegia, and 1 case died. The 30-day complication rate was 18.2%, and the 30-day mortality was 9.1%. The operation time of the patients with open repair was (560±245) min, and the intraoperative blood loss was (6 100±4 536) mL. Twelve patients had complications in the early 30 days after surgery, including 1 paraplegia and 4 deaths within 30 days. The 30-day complication rate was 66.7%, and the 30-day mortality was 22.2%. The bleeding volume in hybrid repair was significantly reduced compared with open repair (P < 0.001). Besides, the incidence of 30-day complications in hybrid surgery was significantly reduced (P=0.011). During the follow-up period, there were 4 reinterventions and 3 deaths in hybrid repair group. The 1-year, 5-year, and 10-year all-cause survival rates were 72%, 54%, and 29%, respectively. In open repair group, reintervention was performed in 1 case and 5 cases died, and the 1-year, 5-year, and 10-year all-cause survival rates were 81%, 71%, and 35%, respectively. There was no significant difference between hybrid repair and open repair in all-cause survival and aneurysm-specific survival.

CONCLUSION

Hybrid approach utilizing visceral debranching with endovascular aneurysm repair is a safe and effective surgical method for high-risk patients with thoracoabdominal aortic aneurysms. The incidence of early postoperative complications and mortality is significantly reduced compared with traditional surgery, but the efficacy in the medium and long term still needs to be improved.

Extensive cell salvage and postoperative outcomes following thoracoabdominal and descending aortic repair

OBJECTIVE

Cell salvage (CS) reduces intraoperative blood transfusion. However, it may cause deformity of the red blood cells and loss of coagulation factors, which may lead to unwanted sequelae. Thus, we hypothesized that extensive CS would lead to adverse outcomes after descending/thoracoabdominal aortic aneurysm (D/TAAA) repair.

METHODS

Between 1991 and 2017, 2012 patients undergoing D/TAAA repair were retrospectively reviewed. After we excluded patients without reported intraoperative CS amount, patients were enrolled in the study (N = 1474) and divided into 2 groups: low CS (salvaged units <40, N = 983) and high CS (salvaged units ≥40, N = 491). Analyses were performed to verify the extensive CS as the risk factor for adverse outcomes.

RESULTS

Preoperative demographics showed that the high-CS group had a significantly greater incidence of male patients (72% vs 58%), heritable aortic disease (24% vs 17%), redo (27% vs 20%), greater glomerular filtration rate (mL/min/1.73 m², 75 vs 66) and more extensive aneurysms (TAAA extent II-IV). The high-CS group had significantly more postoperative complications compared with the low-CS group, including respiratory failure, renal failure, cardiac complications, neurologic deficits, bleeding, and 30-day mortality. Multivariable analysis confirmed high CS was an independent risk factor for renal failure along with long bypass time, older age, and extent of repairs. There was an incremental risk of renal failure and 30-day mortality proportional to salvaged cell unit (P < .001 in both).

CONCLUSIONS

Increased salvaged cell units were associated with adverse postoperative outcomes after D/TAAA repairs. Risk of renal failure and mortality increased proportionally to the salvaged cell units.

Predicting the Need for Intra-operative Large Volume Blood Transfusions During Thoraco-abdominal Aortic Aneurysm Repair

OBJECTIVE

Thoraco-abdominal aortic aneurysm (TAAA) repair is a complex procedure performed in patients at high cardiovascular risk. High volume intra-operative bleeding is often recorded, and the amount of intra-operative blood product transfusion is associated with relevant morbidity and mortality. The aim of the study was to identify pre-operative predictors of intra-operative large volume blood transfusions (LVBT) to stratify patients pre-operatively.

METHODS

This was a retrospective analysis of prospectively collected data of all patients who underwent open TAAA surgery at San Raffaele Scientific Institute from January 2009 to December 2015. Intra-operative red blood cell (RBC) transfusions were administered to maintain a hematocrit of at least 30%. A LVBT was defined as a transfusion of at least four RBC units, corresponding to 1000 mL.

RESULTS

The study population included 428 patients: 260 (61%) received fewer than 4 RBC units, and 168 (39%) were transfused with at least 4 RBC units. In patients who underwent LVBT, higher mortality was observed after surgery (p=.003), longer intensive care unit admission (p=.004), and longer mechanical ventilation compared with less transfused patients (p=.0002). The patients who received fewer units were administered a higher dose of heparin during the surgical operation compared with patients of the LVBT group: 3400±1100 vs. 2900±1300 IU (international units) (p=.0004). Pre-operative chronic renal failure (OR 1.8), the pre-operative haemoglobin value (OR 0.8), and the need for urgent or emergent surgery (OR 3.15) were independent predictors of LVBT on multivariate analysis.

CONCLUSIONS

The identification of patients at risk of intra-operative LVBT during TAAA surgery is critical as these patients experience a worse outcome. Nevertheless, only few independent predictors are available for clinical practice.

Assessment of the relationships among coagulopathy, hyperfibrinolysis, plasma lactate, and protein C in dogs with spontaneous hemoperitoneum

OBJECTIVE

To relate coagulation and fibrinolysis derangements to shock severity as reflected by plasma lactate concentrations in dogs with spontaneous hemoperitoneum (SHP) and determine the impact on transfusions.

DESIGN

Prospective, observational, case-control study.

SETTING

Three veterinary teaching hospitals.

ANIMALS

Twenty-eight client-owned dogs with SHP and 28 breed- and age-matched control dogs.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Blood samples for platelet counts, coagulation, and anticoagulant assays (prothrombin time, activated partial thromboplastin time, fibrinogen, antithrombin, and protein C, thromboelastography [TEG]), fibrinolysis testing (d-dimer and TEG lysis parameters with and without the addition of 50 U/mL of tissue plasminogen activator [TEG LY30 measured with the addition of 50 U/mL of tPA to the blood sample, LY3050 and TEG LY60 measured with the addition of 50 U/mL of tPA to the blood sample, LY6050 ; LY30 and LY60]), and plasma lactate as an indicator of severity of shock were collected from SHP dogs at the time of diagnosis. SHP dogs were hypocoagulable (prolonged prothrombin time and activated partial thromboplastin time, decreased TEG maximum amplitude) and hyperfibrinolytic (increased LY3050 and TEG LY6050 ) compared to controls. The severity of hypocoagulability was related to protein C activity, while the severity of hyperfibrinolysis was related to plasma lactate concentration. Among the 18 dogs discharged from the hospital, LY3050 was significantly associated with the dose of fresh frozen plasma administered, but none of the parameters were associated with the dose of red blood cells administered.

CONCLUSIONS

Dogs with SHP have evidence of hypocoagulability, protein C deficiency, and hyperfibrinolysis. Parameters of hyperfibrinolysis were related to plasma lactate concentrations and volume of plasma transfused during hospitalization. These derangements resemble those found in people with acute coagulopathy of trauma and shock, and activation of protein C may be a common feature to both syndromes.

Postoperative ICU management of vascular surgery patients

Critical care management of vascular surgical patients poses significant challenges owing to patients' comorbidities and the magnitude of the surgical procedures. The primary goals of the anesthesiologist and intensivist are reestablishing preoperative homeostasis, optimizing hemodynamics until return of normal organ function, and managing postoperative complications promptly and effectively. Postoperative critical care management demands a detailed knowledge of the various vascular surgical procedures and the potential postoperative complications. In this review, the authors describe the postoperative complications related to the major specific vascular surgical procedures and their perioperative management.

[Blood transfusion via the cardiopulmonary bypass circuit: the anesthesiologist point of view]

Cardiac surgery frequently requires blood transfusion. The use of transfusion should be restricted due to side effects. Blood transfusion via the cardiopulmonary bypass (CPB) circuit is easy and allows a fast transfusion. The administration of packed red cells is relatively frequent because of the CPB-induced hemodilution and of the higher rate of postoperative complications when the haematocrit during CPB decreases below 20%. This transfusion of packed red cells does not seem to be associated with complications during CPB. Platelet transfusion during bypass is illogical because of the destruction of platelets during CPB and must be avoided. Fresh frozen plasma transfusion during CPB is seldom indicated but is possible. It could reverse heparin resistance.

Aprotinin in cardiac surgery

Aprotinin is a naturally occurring serine protease inhibitor that is being used with increasing frequency in cardiac surgery and beyond to reduce blood loss and the need for perioperative blood transfusion. Through inhibition of serine proteases such as plasmin, aprotinin significantly reduces fibrinolysis, thereby aiding hemostasis during surgical procedures. In addition, aprotinin interacts with other factors in the coagulation and fibrinolytic cascade, creating a hemostatic balance, without increasing the risk of thrombosis. These proven benefits are supplemented by the anti-inflammatory properties of aprotinin, which may help curb some of the deleterious effects of cardiopulmonary bypass. This article will review the discovery of aprotinin, its mechanism of action, dosing and adverse effects, and highlight the major recent trials demonstrating its efficacy.

Acute normovolemic hemodilution can aggravate neurological injury after spinal cord ischemia in rats

BACKGROUND

Acute normovolemic hemodilution (ANH) is currently performed during thoracoabdominal aortic surgery. However, the effects of ANH on spinal cord ischemic injury are currently unknown. Because hemodilution below a certain level of hematocrit (Hct) aggravates the neurological damage after cerebral ischemia, we hypothesized that ANH may increase neurological damage after spinal cord ischemia. The aim of these experiments was to determine the effects of ANH on spinal cord ischemic injury.

METHODS

Thirty male Sprague-Dawley rats were randomly assigned to 1 of the following 3 groups: no hemodilution (group C), target Hct level of 30% (group HD30), and target Hct level of 25% (group HD25). ANH was performed upon withdrawal of blood and simultaneous replacement with the same volume with hydroxyethyl starch. Spinal cord ischemia and reperfusion were induced by using a balloon-tipped catheter placed in the descending thoracic aorta, and changes in mean arterial blood pressure were recorded. Neurological function of the hindlimbs was evaluated for 7 days and recorded using a motor deficit score (MDS) (0 = normal; 5 = complete paraplegia). The number of motor neurons within the spinal cord was counted after final MDS evaluation.

RESULTS

Group HD25 developed hypotension during the latter part of the ANH procedure. Group C and group HD30 experienced 3 minutes of reperfusion hypotension, whereas 6 minutes of hypotension was observed in group HD25. Two rats in group HD25 died during the experimental period. Seven days after reperfusion, the MDS of group C, group HD30, and group HD25 was 1.0 (0.5-2.0), 1.0 (0.5-2.0), and 4.0 (2.8-4.2) (median [95% confidence interval]), respectively. Group HD25 showed significantly higher MDS compared with group C (corrected P = 0.0018; 95% CI for median difference = 1.0-3.5). Motor neuron numbers in the anterior horns of group C, group HD30, and group HD25 were 26.5 (25.0-27.5), 23.5 (22.0-26.5), and 12.5 (8.4-16.6) (median [95% CI]), respectively. Motor neuron numbers of group HD25 were significantly lower than those of group C (corrected P < 0.0001; 95% CI for median difference = 9.0-18.0).

CONCLUSION

The results of the present study indicate that intraoperative ANH to an Hct of 25%, combined with coincident hypotension, caused a delayed recovery of baseline mean arterial blood pressure during the reperfusion period and aggravated neurological outcome after spinal cord ischemia.

Magnesium sulfate does not protect spinal cord against ischemic injury

OBJECTIVE

We tested various doses of MgSO(4) to investigate the effect of Mg on a spinal cord ischemia.

METHODS

Rats were treated with either MgSO(4) (30, 100, or 300 mg/kg; group Mg(low), group Mg(medium), group Mg(high), respectively, n = 10 for each) or saline (control group; n = 10) before ischemia. Spinal cord ischemia was induced using a balloon-tipped catheter placed on proximal descending aorta. During surgery, hemodynamic variables were recorded before ischemia, during aortic occlusion and after reperfusion. Neurologic function was assessed using the motor deficit index (MDI; 0 = normal, 6 = complete paralysis) until seven days after reperfusion, and histologic examination of spinal cord was performed.

RESULTS

After reperfusion, the mean arterial pressure in the group Mg(high) was significantly lower than other groups. Compared to the control group, the groups Mg(low) and Mg(medium) did not show any difference in MDI and the group Mg(high) showed significantly higher MDI. The number of normal motor neurons was similar among other groups except the group Mg(high) had a significantly fewer normal motor neurons.

CONCLUSIONS

Intravenous MgSO(4) with low or medium dose (30, or 100 mg/kg) did not improve neurological injury following spinal cord ischemia. Furthermore, higher dose of MgSO(4) (300 mg/kg) resulted in hemodynamic instability and aggravated neurologic outcome.