Vacuum-assisted venous return reduces blood usage

Vacuum assisted and gravitational venous drainage in aortic valve surgery: A propensity-match study

INTRODUCTION

Vacuum assisted venous drainage (VAVD) is widely adopted in minimally invasive cardiac surgery. VAVD enables the advantage of using smaller cannulae in a reduced surgical field while allowing satisfactory drainage and pump flow. The production of gaseous micro-emboli is a recognized risk associated with VAVD, however no difference in clinical endpoints have been reported between patients operated on with gravity venous drainage (GVD) or with VAVD. Due to the paucity of data on selected surgical populations, we sought to evaluate the early outcomes of patients undergoing isolated aortic valve replacement using VAVD or GVD.

METHODS

Data on 521 patients between 09/2016 and 09/2022 were retrieved from our internal database. Patients were divided into two groups according to use VAVD or GVD. A propensity match analysis was performed to account for difference between the two groups.

RESULTS

The propensity match provided two well balanced cohorts with 129 patients each. A minimally invasive access was used in 97% of the cases in VAVD group vs 98% in GVD group (p = .68). Mean cardiopulmonary by-pass (CPB) time was 71 vs 73 min (p = .74), respectively. There was no difference in lactates peak (p = .19) and urine output during CPB (p = .74). We registered two in-hospital deaths in VAVD cohort (1.6%) vs. no mortality in GVD group (p = .5). Postoperative cerebral stroke occurred in 1 patient in GVD cohort vs. 0 in VAVD (p = 1). Severe postoperative acute kidney injury complicated the course in 16 patients in GVD group and in 5 patients who had VAVD (p = .012). VAVD was associated with a higher number of patients with elevated postoperative AST (p = .07) and Troponin I (p = .01) values.

CONCLUSIONS

The use of VAVD during isolated aortic valve replacement was not associated with increased risks of postoperative complications and in-hospital mortality with results that were at least similar to those registered in a matched cohort of patients operated on with GVD.

Increasing surgeon experience and cumulative institutional experience drive decreasing hospital mortality after reoperative cardiac surgery

OBJECTIVE

The study objective was to identify the effects of surgeon experience and age, in the context of cumulative institutional experience, on risk-adjusted hospital mortality after cardiac reoperations.

METHODS

From 1951 to 2020, 36 surgeons performed 160,338 cardiac operations, including 32,871 reoperations. Hospital death was modeled using a novel tree-bagged, generalized varying-coefficient method with 6 variables reflecting cumulative surgeon and institutional experience up to each cardiac operation: (1) number of total and (2) reoperative cardiac operations performed by a surgeon, (3) cumulative institutional number of total and (4) reoperative cardiac operations, (5) year of surgery, and (6) surgeon age at each operation. These were adjusted for 46 patient characteristics and surgical components.

RESULTS

There were 1470 hospital deaths after cardiac reoperations (4.5%). At the institutional level, hospital death decreased exponentially and became less variable, leveling at 1.2% after approximately 14,000 cardiac reoperations. For all surgeons as a group, hospital death decreased rapidly over the first 750 reoperations and then gradually decreased with increasing experience to less than 1% after approximately 4000 reoperations. Surgeon age up to 75 years was associated with ever-decreasing hospital death.

CONCLUSIONS

Surgeon age and experience have been implicated in adverse surgical outcomes, particularly after complex cardiac operations, with young surgeons being novices and older surgeons having declining ability. However, at Cleveland Clinic, outcomes of cardiac reoperations improved with increasing primary surgeon experience, without any suggestion to mid-70s of an age cutoff. Patients were protected by the cumulative background of institutional experience that created a culture of safety and teamwork that mitigated adverse events after cardiac surgery.

Development of a cannula device for gas fraction removal in surgical drains

The development of low-traumatic surgical drains aimed at maximum possible separation of blood and air, is an important trend in modern medicine. The objective of this work is to create an inexpensive, user-friendly and low-traumatic dynamic blood aspiration system (DBAS). The system allows effective separation of blood and air when drawing blood from a wound under vacuum conditions required for blood aspiration. The operating principle of the system is to separate liquid and gas fractions of the blood-air mixture by modifying the blood intake cannula. The effect is achieved by applying the principles of centrifugal forces of a rotating blood-air flow combined with Archimedes lift forces.

Vacuum-assisted venous drainage in adult cardiac surgery: a propensity-matched study

OBJECTIVES

Conventional cardiopulmonary bypass with gravity drainage leads inevitably to haemodilution. Vacuum-assisted venous drainage (VAVD) utilizes negative pressure in the venous reservoir, allowing active drainage with a shortened venous line to reduce the priming volume. The goal of this study was to analyse the efficacy and safety of VAVD.

METHODS

Data on 19 687 patients (18 681 with gravity drainage and 1006 with VAVD) who underwent cardiac operations between 1 January 2015 and 31 January 2018 were retrospectively collected from a single centre. Propensity matching identified 1002 matched patient pairs with VAVD and gravity drainage for comparison of blood product transfusion rate, major morbidities and in-hospital mortality rates.

RESULTS

The blood transfusion rate of the VAVD group was lower than that of the gravity drainage group (28.1% vs 35% for red blood cells, 13% vs 18% for fresh frozen plasma and 0.1% vs 1.8% for platelets; P = 0.0009, 0.0020 and <0.0001, respectively). The mean difference (95% confidence interval) between the groups for red blood cells, fresh frozen plasma and platelets was -6.9% (-11.0% to -2.8%), -5.0% (-8.1% to -1.8%) and -1.7% (-2.5% to -0.9%), respectively. No difference was observed regarding the major morbidities of cerebrovascular accidents, acute kidney injury, hepatic failure and perioperative myocardial infarction and the in-hospital deaths between the 2 groups.

CONCLUSIONS

VAVD was associated with a reduction in blood product transfusions, and an increase in the risk of major morbidities and in-hospital deaths of the VAVD group was not observed.

Single Venous Return for Mitral Valve Operations

Objective

Most cardiac surgeons routinely perform bicaval venous cannulation for mitral valve operations. We describe the technique and advantage of a single-venous cannulation strategy.

Methods/Results

Single venous cannulation with a 29-French small-bore cannula (facilitated by vacuum-assisted venous drainage) yields reliable decompression of the right heart and affords outstanding exposure of the mitral valve.

Conclusions

We recommend and use this technique for all mitral valve operations not requiring opening the right atrium.

Does full sternotomy have more significant impact than the cardiopulmonary bypass time in patients of mitral valve surgery?

Background

Over the past decade, minimally invasive mitral valve surgery (MIMVS) has grown in popularity. Less invasive approaches to mitral valve surgery are increasingly used for improved cosmesis. We sought to compare these minimally invasive approaches fairly with conventional full sternotomy approaches by using propensity-matching methods.

Methods

From January 2011 to January 2017, a total of 1120 isolated mitral valve operations were performed at our institution. Data were retrospectively collected on all patients, and a logistic regression model was created to predict selection to a minimally invasive versus conventional sternotomy approach. Propensity scores were then generated based on the regression model and matched pairs created using 1:1 nearest neighbor matching. There were 165 matched pairs in the analysis (sternotomy, n = 165;MIMVS, n = 165). Clinical outcomes included bypass and cross-clamp time, length of hospitalization, morbidity, and mortality. Patient details and follow-up outcomes were compared using multivariate, and Kaplan–Meier analyses.

Results

The minimally invasive approach led to slightly longer cardiopulmonary bypass time (99 ± 25 vs 88 ± 17 min, p <0.001), and cross-clamp time (65 ± 13 vs 49 ± 11 min, p<0.001). Overall, no significant differences existed among major in-hospital complications between groups. There were no differences between the matched groups in 30-day mortality (1.2% vs 0.6%, p >0.05). However, Chest tube drainage was lower at 6 and 24 h after a minimally invasive approach (30 ± 5 mL) and 120 ± 20 mL than after conventional sternotomy 175 ± 50 mL and 400 ± 150 mL at these times (p < 0.001). Transfusion was less frequent after minimally invasive surgery than after conventional surgery (15.7% vs 40.6%, p < 0.001). Patients undergoing minimally invasive surgery spent less time on ventilation support (6.2 ± 1.1 h vs 10.4 ± 2.7, p < 0.001). The multivariable regression analysis showed the full sternotomy was an independent risk factor for the propensity-adjusted likelihood of postoperative transfusion, re-exploration for bleeding, and postoperative ventilation support (p < 0.05). But the duration of cardiopulmonary bypass time was not an independent risk factor. The mean duration of survival follow-up was 4.4 ± 1.2 years. However, comparison of survival curves between the two groups revealed no significant difference (P = 0.203). With regard to freedom from valve-related morbidity, there was no significant difference between groups (P = 0 .574).

Conclusion

Within that portion of the spectrum of mitral valve surgery in which propensity matching was possible, minimally invasive mitral valve surgery has cosmetic, blood product use, and respiratory advantages over conventional surgery, and no apparent detriments. However, minimally invasive mitral valve surgery required a slightly longer cardiopulmonary bypass time and cross-clamp time. Minimally invasive mitral valve surgery represents a safe and effective surgical technique that we believe should be used more routinely in the surgical management of mitral valve disease. MIMVS provides equally durable midterm results as the standard sternotomy approach.

Blood Conservation in Cardiac Surgery

Blood transfusion is the most common procedure in cardiac surgery. Increasing evidence exists that excess transfusions are harmful to patients. Transfusion reactions and complications, including infection, immune modulation, and lung injury, are known complications but underreported; hence, their significance is often disregarded. Furthermore, a number of randomized trials have shown that a restrictive transfusion strategy is equal to if not better than a liberal transfusion strategy. Despite the evidence for the use of restrictive transfusion triggers, its dissemination in the cardiac surgical community has met with resistance. In this review, we outline the risks of transfusion, compare restrictive and liberal transfusion strategies in cardiac surgery, and finally outline perioperative interventions to minimize transfusion in the cardiac surgical patient.

Vacuum-assisted drainage in cardiopulmonary bypass: advantages and disadvantages

Systematic review of vacuum assisted drainage in cardiopulmonary bypass, demonstrating its advantages and disadvantages, by case reports and evidence about its effects on microcirculation. We conducted a systematic search on the period 1997-2012, in the databases PubMed, Medline, Lilacs and SciELO. Of the 70 selected articles, 26 were included in the review. Although the vacuum assisted drainage has significant potential for complications and requires appropriate technology and professionalism, prevailed in literature reviewed the concept that vacuum assisted drainage contributed in reducing the rate of transfusions, hemodilutions, better operative field, no significant increase in hemolysis, reduced complications surgical, use of lower prime and of smaller diameter cannulas.

Perfusion techniques for minimally invasive valve procedures

In this paper, we present, in detail, the simplified perfusion technique that we have adopted since January 2009 and that we have utilized in 200 cases for cardiac minimally invasive valvular procedures that were performed through a right lateral mini-thoracotomy in the 3(rd)-4(th) intercostal space. Cardiopulmonary bypass was achieved by means of the direct cannulation of the ascending aorta and the insertion of a percutaneous venous cannula in the femoral vein. A flexible aortic cross-clamp was applied through the skin incision and cardioplegic arrest was obtained with the antegrade delivery of a crystalloid solution. Gravity drainage was enhanced by vacuum-assisted aspiration. There were no technical complications related to this perfusion technique that we have adopted in minimally invasive surgical procedures.

Less invasive versus conventional heart valve surgery in patients with severe heart failure

OBJECTIVE

Patients with severe heart failure might benefit from reduced operative trauma, but rarely undergo less-invasive valve surgery. The present study compared the outcomes of less-invasive heart valve surgery with those of complete sternotomy in such patients.

METHODS

From January 1995 to July 2010, 871 patients in New York Heart Association class III or IV underwent valve surgery (aortic or mitral, or both). A less-invasive approach was used in 205. Propensity score matching yielded 185 matched pairs for outcomes comparison adjusted for patient characteristics and 139 pairs adjusted further for individual surgeon.

RESULTS

Without considering surgeons, myocardial ischemic times (59 ± 27 vs 64 ± 26 minutes, P = .04), cardiopulmonary bypass times (75 ± 35 vs 86 ± 34 minutes, P < .0001), and intensive care unit stays (median, 24 vs 43 hours; P = .007) were shorter for less-invasive surgery. Hospital morbidity, mortality (1.6% [3 of 185] vs 2.7% [5 of 185]; P = .5), and long-term survival (53% and 48% at 12 years; P = .3) were similar. After considering the surgeon, these benefits were not apparent; rather, efficiency, safety, and effectiveness were equivalent to those of complete sternotomy. Thus, myocardial ischemic (63 ± 30 vs 62 ± 25 minutes, P = .8) and cardiopulmonary bypass (80 ± 40 vs 81 ± 31 minutes, P = .5) times were similar, as were intensive care unit stay (median, 28 vs 30 hours; P = .09), postoperative complications, in-hospital mortality (2.2% [3 of 139] vs 3.6% [5 of 139]; P = .5), and long-term survival (57% and 53% at 12 years; P = .5).

CONCLUSIONS

In selected patients with severe heart failure, less-invasive valve surgery is a viable option, yielding at least equivalent efficiency, safety, and effectiveness to complete sternotomy. However, achieving these outcomes requires surgeons experienced in less-invasive surgery.

Blood transfusion and infection after cardiac surgery

Cardiac surgery is the largest consumer of blood products in medicine; although believed life saving, transfusion carries substantial adverse risks. This study characterizes the relationship between transfusion and risk of major infection after cardiac surgery. In all, 5,158 adults were prospectively enrolled to assess infections after cardiac surgery. The most common procedures were isolated coronary artery bypass graft surgery (31%) and isolated valve surgery (30%); 19% were reoperations. Infections were adjudicated by independent infectious disease experts. Multivariable Cox modeling was used to assess the independent effect of blood and platelet transfusions on major infections within 60 ± 5 days of surgery. Red blood cells (RBC) and platelets were transfused in 48% and 31% of patients, respectively. Each RBC unit transfused was associated with a 29% increase in crude risk of major infection (p < 0.001). Among RBC recipients, the most common infections were pneumonia (3.6%) and bloodstream infections (2%). Risk factors for infection included postoperative RBC units transfused, longer duration of surgery, and transplant or ventricular assist device implantation, in addition to chronic obstructive pulmonary disease, heart failure, and elevated preoperative creatinine. Platelet transfusion decreased the risk of infection (p = 0.02). Greater attention to management practices that limit RBC use, including cell salvage, small priming volumes, vacuum-assisted venous return with rapid autologous priming, and ultrafiltration, and preoperative and intraoperative measures to elevate hematocrit could potentially reduce occurrence of major postoperative infections.

Venous drainage--gravity or assisted?

Since the early start of cardiopulmonary bypass, vascular access has been recognized as a main variable for obtaining optimal blood flow during cardiopulmonary bypass. In particular, venous drainage can limit the maximum flow as the wide, low-resistance, collapsible veins are connected with smaller stiff cannulas and tubing. Due to the introduction of long venous cannulas for minimally invasive cardiac surgery and the desire to limit hemodilution during cardiopulmonary bypass, more and more centers have started using assisted venous drainage techniques. This article gives an overview of these techniques, with their respective advantages and disadvantages.

Using decision-analysis and meta-analysis to predict coronary artery bypass surgical outcomes – a model for comparing off-pump surgery to miniaturized cardiopulmonary bypass circuits

Coronary artery bypass (CABG) surgery with cardiopulmonary bypass (CPB) has been the “gold standard” for many years. However, methods to conduct off-pump coronary artery bypass (OPCAB) surgery with a beating heart have decreased the use of CPB. Improvements in cardiopulmonary bypass technology, using low-prime circuits with retrograde autologous prime, have demonstrated a reduction in blood use while maintaining the surgical advantage of increased revascularization associated with on-pump surgery. A meta-analysis of published randomized clinical trials was used to compare the outcomes. These outcomes included the number of grafts, hospital length of stay, and transfusion rate. They were then incorporated into a decision-analysis model to compare OPCAB with the on-pump surgery, using both conventional high-prime (HP) and low-prime circuits with retrograde autologous prime (LP/RAP). The meta-analysis of randomized clinical trials revealed that OPCAB surgery had 0.33 less grafts (p < .05), a reduction of 0.97 days in hospital length of stay (LOS) (p < .05), and a 63.2% reduction in percentage of patients transfused (p < .05). Based on the decision-analysis model, a relatively low major event rate (defined as myocardial infarction, need for angioplasty or surgery) at 4 years of 2% can eliminate the savings associated with OPCAB when compared to a low-prime circuit with RAP. Using a 5% major event rate at 4 years, the predicted cost savings of LP/RAP over OPCAB is $510 per patient or $51,036,746 per 100,000 patients. The development and implementation of low-prime circuits with retrograde autologous prime is an import step in matching the outcomes associated with OPCAB surgery.

An In Vitro and In Vivo Study of the Detection and Reversal of Venous Collapse During Extracorporeal Life Support

The objective of this study was to investigate venous collapse (VC) related to venous drainage during the use of an extracorporeal life support circuit. A mock circulation was built containing a centrifugal pump and a collapsible vena cava model to simulate VC under controlled conditions. Animal experiments were performed for in vivo verification. Changing pump speed had a different impact on flow during a collapsed and a distended caval vein in both models. Flow measurement in combination with pump speed interventions allows for the detection and quantitative assessment of the degree of VC. Additionally, it was verified that a quick reversal of a VC situation could be achieved by a two-step pump speed intervention, which also proved to be more effective than a straightforward decrease in pump speed.

Open and closed chest extrathoracic cannulation for cardiopulmonary bypass and extracorporeal life support: methods, indications, and outcomes

Extrathoracic cannulation to establish cardiopulmonary bypass has been widely applied in recent years and includes: (a) repeat surgery, (b) minimally invasive surgery, and (c) cases with diseased vessels such as porcelain, aneurysmal, and dissecting aorta. In addition, the success and relative ease of peripheral cannulation, among other technological advances, has permitted the development of closed chest extracorporeal life support, in the form of cardiopulmonary support and extracorporeal membrane oxygenation. With this development have come applications for cardiopulmonary bypass based support outside the traditional cardiac theatre setting, including emergency circulatory support for patients in cardiogenic shock and respiratory support for patients with severely impaired gas exchange. This review summarises the approach to extrathoracic cannulation for the generalist.

A review of the application of propensity score methods yielded increasing use, advantages in specific settings, but not substantially different estimates compared with conventional multivariable methods

OBJECTIVE

Propensity score (PS) analyses attempt to control for confounding in nonexperimental studies by adjusting for the likelihood that a given patient is exposed. Such analyses have been proposed to address confounding by indication, but there is little empirical evidence that they achieve better control than conventional multivariate outcome modeling.

STUDY DESIGN AND METHODS

Using PubMed and Science Citation Index, we assessed the use of propensity scores over time and critically evaluated studies published through 2003.

RESULTS

Use of propensity scores increased from a total of 8 reports before 1998 to 71 in 2003. Most of the 177 published studies abstracted assessed medications (N=60) or surgical interventions (N=51), mainly in cardiology and cardiac surgery (N=90). Whether PS methods or conventional outcome models were used to control for confounding had little effect on results in those studies in which such comparison was possible. Only 9 of 69 studies (13%) had an effect estimate that differed by more than 20% from that obtained with a conventional outcome model in all PS analyses presented.

CONCLUSIONS

Publication of results based on propensity score methods has increased dramatically, but there is little evidence that these methods yield substantially different estimates compared with conventional multivariable methods.

Magnesium as a neuroprotectant in cardiac surgery: A randomized clinical trial

OBJECTIVE

We sought to evaluate magnesium as a neuroprotectant in patients undergoing cardiac surgery with cardiopulmonary bypass.

METHODS

From February 2002 to September 2003, 350 patients undergoing elective coronary artery bypass grafting, valve surgery, or both were enrolled in a randomized, blinded, placebo-controlled trial to receive either magnesium sulfate to increase plasma levels 1(1/2) to 2 times normal during cardiopulmonary bypass (n = 174) or no intervention (n = 176). Neurologic function, neuropsychologic function, and depression were assessed preoperatively, at 24 and 96 hours after extubation (neurologic) and at 3 months (neuropsychologic, depression). Neurologic scores were analyzed using ordinal longitudinal methods, and neuropsychologic and depression inventory data were summarized by principal component analysis, followed by linear regression analysis using component scores as response variables.

RESULTS

Seven (2%) patients had a postoperative stroke, 2 (1%) in the magnesium and 5 (3%) in the placebo group (P = .4). Neurologic score was worse postoperatively in both groups (P < .0001); however, magnesium group patients performed better than placebo group patients (P = .0001), who had prolonged declines in short-term memory and reemergence of primitive reflexes. Three-month neuropsychologic performance and depression inventory score were generally better than preoperatively, with few differences between groups (P > .6); however, older age (P = .0006), previous stroke (P = .003), and lower education level (P = .0007) were associated with worse performance.

CONCLUSIONS

Magnesium administration is safe and improves short-term postoperative neurologic function after cardiac surgery, particularly in preserving short-term memory and cortical control over brainstem functions. However, by 3 months, other factors and not administration of magnesium influence neuropsychologic and depression inventory performance.

Vacuum-Assisted Venous Drainage during Fetal Cardiopulmonary Bypass

We investigated a miniature magnetically levitated centrifugal blood pump intended to deliver 0.3-1.5 l/min of support to neonates and infants. The back clearance gap between the housing and large volume of the rotor, where the suspension and motor bearings are located, forms a continuous leakage flow path. Within the gap, flow demonstrates a very complex three-dimensional structure: the fluid adjacent to the rotating disk tends to accelerate by centrifugal force to flow radially outwards toward the outlet of the impeller against an unfavorable pressure gradient, which in turn forces blood to return along the stationary housing surfaces. Consequently, one or multiple vortices may be generated in the gap to block blood flow and cause the formation of a retrograde and antegrade leakage flow phenomenon at the gap outlet using an optimization process including extensive computational fluid dynamics (CFD) analysis of impeller refinements, we found that secondary blades located along the back or extended to the side surfaces of the rotor have the capacity to reduce and eliminate the retrograde flow in the back clearance gap. Flow visualization confirmed the CFD-predicted flow patterns. This work demonstrates the utility of CFD-based design optimization to optimize the fluid path of a miniature centrifugal pump.