Vacuum-assisted Venous Drainage Research Articles

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

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. 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. 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. 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.

Single-Center Experience With a Self-Expandable Venous Cannula During Minimally Invasive Cardiac Surgery.

Venous drainage is often problematic in minimally invasive cardiac surgery (MICS). Here, we describe our experience with a self-expandable stent cannula designed to optimize venous drainage. The smart canula® was used in 58 consecutive patients undergoing MICS for mitral valve disease (n = 40), left atrial myxoma (n = 3), left ventricular outflow tract obstruction (n = 1), and aortic valve replacement via a right anterior minithoracotomy (n = 14) procedures. The venous cannula was placed under transesophageal echocardiography guidance to reach the superior vena cava. Vacuum-assisted venous drainage (between -20 and -35 mm Hg) was used to reach a target flow index of 2.2 L/min/m² at a core temperature of 34 °C using a goal-directed perfusion strategy aimed at a minimum DO2 of 272 mL/min/m2. Cardiopulmonary bypass (CPB) parameters were recorded, and hemolysis-related parameters were analyzed on postoperative days 1 to 7. Mean body surface area and median body mass index were 1.9 ± 0.2 m2 and 25.2 (23.4, 30.2) kg/m2. Mean CPB and median cross-clamping times were 107.7 ± 24.4 min and 64.5 (53, 75.8) min, and median CPB flow during cardioplegic arrest was 4 (3.6, 4.2) L/min (median cardiac index 2.1 [2, 2.2] L/min/m²). Venous drainage was considered sufficient by the surgeon in all cases, and insertion and removal were uncomplicated. Mean SvO2 during CPB was 80.2% ± 5.5%, and median peak lactate was 10 (8, 14) mg/dL, indicating sufficient perfusion. Mean venous negative drainage pressure during cross-clamping was 27.2 ± 12.3 mm Hg. Platelets dropped by 73.6 ± 37.5 K/µL, lactate dehydrogenase rose by 81.5 (44.3, 140.8) U/L, and leukocytes rose by 3.4 (2.2, 7.2) K/µL on postoperative day 1. The venous smart canula® allows for optimal venous drainage at low negative drainage pressures, facilitating sufficient perfusion in MICS.

Minimally invasive pulmonary valve replacement via left anterior minithoracotomy.

ABSTRACT Pulmonary valve replacement is one of the most common indications for reoperation in adults with congenital heart disease. Finding an alternative to repeat median sternotomy may facilitate recovery and shorten hospital stay. We present our technique of left anterior minithoracotomy for pulmonary valve replacement.

An evaluation of hard-shell venous reservoir integrated pressure relief valve pressure mitigation performance.

Vacuum assisted venous drainage (VAVD) requires the sealing of the hard-shell venous reservoir, thereby creating circumstances where reservoir pressurization may occur. Manufacturers utilize integrated pressure relief valves (IPRV) to mitigate pressurization risk; however, accidents have been reported even with these devices. We have undertaken a performance evaluation of IPRV's in a large number of hard-shell venous reservoirs. Reservoirs were sealed and gas insufflated while measuring reservoir internal pressure. Linear regression models were developed to depict the association between internal pressure and gas inflow rate. External secondary one-way valves (ESOV) were assessed for pressure mitigation performance. An assisted venous drainage survey was circulated to Canadian Clinical Perfusionists. The reservoirs tested were adult (n = 9, 64%) and pediatric (n = 5, 36%) designs. Significant variability (p < 0.001) in internal reservoir pressures (range: 0.04-161.41 mmHg) was observed across the titrated gas inflow rate (0.5-10.0 l/min). The regression models demonstrate excellent predictive performance (SE: 0.008-0.309). ESOV's reduce the reservoir pressure below that of the IPRV; however, they cannot eliminate reservoir pressurization. The survey showed a majority (91%) of respondents use VAVD, and reservoir pressurization events occur regularly (18%). Significant variability among reservoir's IPRV to mitigate reservoir pressurization exists. The predictive models are extremely accurate at estimating the internal pressure. ESOV performance limitations moderate their utility as a backup pressure mitigation technique. A significant number of reservoir pressurization events are occurring with the use of VAVD. As a result, standardized communication from manufacturers on the purpose and performance of IPRV is recommended in order to delineate the limitations of these devices.

Neck cannulation for bypass in redo sternotomy in children and adults with congenital heart disease.

Patients with complex congenital heart disease carry an increased risk of damage to retrosternal structures each time they undergo redo sternotomy. The aim of this study was to evaluate the safety and efficacy of neck cannulation for peripheral cardiopulmonary bypass to alleviate the risks in high-risk redo sternotomy patients. Children and adults with congenital heart disease undergoing high-risk redo sternotomy were included in this retrospective study. The primary outcome was the safety and efficacy of neck cannulation for cardiopulmonary bypass. The secondary outcome was to assess preoperative risk factors as an indication for neck cannulation. The right common carotid artery and right internal jugular vein were cannulated and full cardiopulmonary bypass was initiated with vacuum-assisted venous drainage. Redo sternotomy was performed on a decompressed heart, and bifrontal regional cerebral oxygen saturation was monitored via near-infrared spectroscopy. In total, 35 patients were included. No mortality, neurological or vascular complications occurred postoperatively. Mean left- and right-sided near-infrared spectroscopy were 70.0% (±10.5) and 64.2% (±12.0), respectively, and the mean difference was 5.7% (±6.9). Main preoperative risk factors were; adherent ascending aorta (45.7%), adherent conduit (40%), severely dilated retrosternal right ventricle (17.1%) and skeletal deformations (14.3%). Cannulation of the right neck vessels for peripheral cardiopulmonary bypass prior to high-risk redo sternotomy in children and adults with congenital heart disease is a safe and effective strategy. In combination with near-infrared spectroscopy monitoring, adequate cerebral oxygenation can be ensured while the risk of catastrophic haemorrhage is minimized.

Impact of Vacuum-Assisted Venous Drainage on Forward Flow in Simulated Pediatric Cardiopulmonary Bypass Circuits Utilizing a Centrifugal Arterial Pump Head.

ObjectiveTo analyze the impact of vacuum-assisted venous drainage (VAVD) on arterial pump flow in a simulated pediatric cardiopulmonary bypass circuit utilizing a centrifugal pump (CP) with an external arterial filter.MethodsThe simulation circuit consisted of a Quadrox-I Pediatric oxygenator, a Rotaflow CP (Maquet Cardiopulmonary AG, Rastatt, Germany), and a custom pediatric tubing set primed with Lactated Ringer's solution and packed red blood cells. Venous line pressure, reservoir pressure, and arterial flow were measured with VAVD turned off to record baseline values. Four other conditions were tested with progressively higher vacuum pressures (-20, -40, -60, and -80 mmHg) applied to the baseline cardiotomy pressure. An arterial filter was placed into the circuit and arterial flow was measured with the purge line in both open and closed positions. These trials were repeated at set arterial flow rates of 1500, 2000, and 2500 mL/min.ResultsThe use of progressively higher vacuum caused a reduction in effective arterial flow from 1490±0.00 to 590±0.00, from 2020±0.01 to 1220±0.00, and from 2490±0.0 to 1830±0.01 mL/min. Effective forward flow decreased with increased levels of VAVD.ConclusionThe use of VAVD reduces arterial flow when a CP is used as the main arterial pump. The reduction in the forward arterial flow increases as the vacuum level increases. The loss of forward flow is further reduced when the arterial filter purge line is kept in the recommended open position.An independent flow probe is essential to monitor pump flow during cardiopulmonary bypass.

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

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. Data on 19687 patients (18681 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. 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. 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.

Simple Redo Proximal Thoracic Aortic Surgery with Peripheral Cardiopulmonary Bypass and Minimal Dissection.

Reoperations on the proximal thoracic aorta are increasingly observed after previous aortic or cardiac operations. Redo proximal aortic surgery remains challenging with an increased mortality compared to first-time operations. For a successful redo proximal aortic surgery in a patient with complex pathological conditions, the surgical procedure and cardiopulmonary bypass (CPB) should be simplified as much as possible. Herein, we report our experience of proximal aortic reoperations in which the strategy consisted of an axillo-axillary (jugular) and a femoro-femoral CPB in combination with minimal dissection of surgical adhesions. Satisfactory full-flow CPB was achieved with peripheral cannulations and the aid of vacuum-assisted venous drainage. A suitable surgical view of the proximal aorta was obtained without dissection of the heart. There was no operative mortality and the peripheral CPB was well managed without technical problems. We consider that the proposed strategy makes proximal aortic reoperations safe and simple.

Gravity Venous Drainage and the 3/8-Inch Venous Line: What Would Poiseuille Do?

The 1/2″ venous line has long been the drainage tubing diameter of choice for adult patients undergoing cardiac surgery. However, several programs use a smaller diameter venous line when used in conjunction with kinetic-assisted venous drainage or vacuum-assisted venous drainage. In 2014, our perfusion team made an institution-wide effort to miniaturize the cardiopulmonary bypass (CPB) circuit for children. One of our changes was the transition to a 3/8″ diameter venous line for drainage, even in our larger patients (up to 80 kg). We reviewed the current literature on this topic and delineated the various parameters required to be able to use the 3/8″ venous line with gravity drainage with the aim of using it on patients up to 115 kg with the appropriate venous reservoir. We have successfully used the 3/8″ venous line in more than 40 of our larger patients (35–90 kg) without the need for assisted venous drainage. We were able to reduce CPB prime from 625 ± 118 to 425 ± 52 mL before retrograde autologous priming (RAP)/venous autologous priming (VAP). The prime was further reduced to 325 ± 66 mL after RAP/VAP. Homologous blood utilization was reduced from 217 ± 311 mL to 27 ± 77 mL. Both results were statistically significant. We hypothesize that taking into account two of the parameters of Poiseuille’s law, namely length and diameter, it is possible to safely drain large children and mid-size adults via gravity venous drainage and the 3/8″ venous line. This technique allows reducing prime volume, simplifies CPB circuits with increased safety and potentially reduces the need for homologous blood transfusion.

In vitro evaluation of Capiox FX05 and RX05 oxygenators in neonatal cardiopulmonary bypass circuits with varying venous reservoir and vacuum-assisted venous drainage levels.

The purpose of this study was to evaluate the hemodynamic properties and microemboli capture associated with different vacuum-assisted venous drainage (VAVD) vacuum levels and venous reservoir levels in a neonatal cardiopulmonary bypass circuit. Trials were conducted in 2 parallel circuits to compare the performance of Capiox Baby RX05 oxygenator with separate AF02 arterial filter to Capiox FX05 oxygenator with integrated arterial filter. Arterial cannula flow rate to the patient was held at 500mL/min and temperature maintained at 32°C, while VAVD vacuum levels (0mm Hg, -15mm Hg, -30mm Hg, -45mm Hg, -60mm Hg) and venous reservoir levels (50mL, 200mL) were evaluated in both oxygenators. Hemodynamic parameters measuring flow, pressure, and total hemodynamic energy were made in real time using a custom-made data acquisition system and Labview software. Nearly 10cc bolus of air was injected into the venous line and gaseous microemboli detected using an Emboli Detection and Classification Quantifier. Diverted blood flow via the arterial filter's purge line and mean pressures increased with increasing VAVD levels (P<0.01). Mean pressures were lower with lower venous reservoir levels and were greater in RX05 groups compared to FX05 (P<0.01). Microemboli detected at the preoxygenator site increased with higher VAVD vacuum levels and lower venous reservoir levels (P<0.01). The amount of microemboli captured by the FX05 oxygenator with integrated arterial filter was greater than by the RX05 oxygenator alone, although both oxygenators were able to clear microemboli before reaching the pseudo-patient.

RF01 ANGIO-VAC ASPIRATION SYSTEM: THE LARGEST ITALIAN SINGLE CENTER EXPERIENCE

Background and Aim: AngioVac system is a vacuum-assisted venous drainage device recently introduced into clinical practice for the removal of fresh and/or soft emboli/thrombi from vessels and right atrium. The aim of this study was presenting our center experience. Methods: From July 2016 to July 2017, 6 patients (mean age 58 ± 15 years) were treated with AngioVac system for right atrial masses (=4, 66.7%, 2 of these were electrode lead vegetations) and thrombosis of inferior vena cava (=2, 33.3%). We used both femoral and jugular vein percutaneous accesses and echo- or fluoroscopy guiding. Results: Therapeutic success (defined as a complete aspiration of the mass or return to an anterograde caval flow) was achieved in 5 cases (83.3%). One percutaneous approach was converted in open-chest because of pericardial tamponade and the mass suction was performed directly through the right atrium. Median intensive care unit stay was 1 day and all patients were discharged in good clinical conditions. At 1-year follow-up, all patients were alive. Conclusions: In our experience, AngioVac is a safe and reliable device that allows good results and patient's fast recovery. Because the procedure requires patient monitoring and the use of venous-venous extracorporeal membrane oxygenation, we suggest performing it in cardiac or hybrid operating room.

Direct Femoral Cannulation in Minimal Invasive Pediatric Cardiac Surgery: Our Experience With Midterm Result.

One of the major challenges faced in minimally invasive pediatric cardiac surgery is cannulation strategy for cardiopulmonary bypass. Central aortic cannulation through the same incision has been the usual strategy, but it has the disadvantage of cluttering of the operative field. We hereby present the results of femoral cannulation in minimally invasive pediatric cardiac surgery in terms of adequacy and safety. From January 2013 to June 2016, 200 children (122 males) with mean ± SD age of 9.2 ± 4.51 years (median = 6 years, range = 3-18 years) and weight of 19.22 ± 8.49 kg (median = 15 kg, range = 8-45 kg) were operated for congenital cardiac defects through anterolateral thoracotomy. The most common diagnosis was atrial septal defect (144 patients). In all the patients, femoral artery and femoral vein were cannulated along with direct superior vena cava cannulation for institution of cardiopulmonary bypass. There were no deaths or any major complications related to femoral cannulation. Femoral artery cannulation provided adequate arterial inflow, whereas femoral vein with direct superior vena cava cannulation provided adequate venous return in all the patients. No patient required vacuum-assisted venous drainage. No patient required conversion to sternotomy or developed vascular, neurological complications. At discharge and at 1-year follow-up, both femoral artery and vein were patent without a significant stenosis on color Doppler ultrasonography in all the patients. At mean ± SD follow-up period of 30.63 ± 10.09 months, all the patients were doing well without any wound-related, neurological, or vascular complications. Femoral arterial and venous cannulation is a feasible, reliable, and efficient method for institution of cardiopulmonary bypass in minimally invasive pediatric cardiac surgery.

Minimally invasive mitral valve repair

### Learning objectives Modified cardiopulmonary bypass techniques, including vacuum-assisted venous drainage, were introduced in 1995 and enabled safe and effective minimally invasive mitral valve (MV) surgery. Approaches have evolved since...

Hemolysis During Open-Heart Surgery With Vacuum-Assisted Venous Drainage at Different Negative Pressures in Pediatric Patients Weighing Less Than 10 kilograms.

This study examined the degree of hemolysis during vacuum-assisted venous drainage at different negative pressures to identify an adequate negative pressure that provides effective venous drainage without significant hemolysis in open-heart surgery in children weighing less than 10 kg. Patients weighing less than 10 kg who underwent surgery for ventricular septal defect or atrial septal defect from 2011 to 2014 were enrolled. We used one of four negative pressures (20, 30, 40, or 60 mm Hg) for each patient. We measured haptoglobin, plasma hemoglobin, aspartate aminotransferase, and lactate dehydrogenase levels in the patients' blood three times perioperatively and determined the potential correlation between the change in each parameter with the level of negative pressure. Forty-six patients were enrolled in this study (mean age: 7.1 ± 7.0 months, mean body weight: 6.1 ± 1.8 kg). There were no significant differences according to the degree of negative pressure with respect to patient age, body weight, cardiopulmonary bypass (CPB) time, aorta cross-clamping time, blood flow during CPB, or lowest body temperature. All parameters that we measured reflected progression of hemolysis during CPB; however, the degree of change in the parameters did not correlate with negative pressure. In pediatric patients weighing less than 10 kg, the change in the degree of hemolysis did not differ with the amount of negative pressure. We may apply negative pressures up to 60 mm Hg without increasing the risk of hemolysis, with almost same the level of hemolysis using negative pressures of 20, 30, and 40 mm Hg for effective venous drainage and an ideal operative field during open-heart surgery.

The Impact of Roller Pump vs. Centrifugal Pump on Homologous Blood Transfusion in Pediatric Cardiac Surgery

Centrifugal pumps are considered to be less destructive to blood elements(1) when compared to roller pumps. However, their large prime volumes render them unsuitable as arterial pumps in heart lung machine (HLM) circuitry for children. In November of 2014, the circuit at Arnold Palmer Hospital, a Biomedicus BP-50 with kinetic assist venous drainage (KAVD) and 1/4″ tubing was converted to a roller pump in the arterial position with gravity drainage. Vacuum-assisted venous drainage (VAVD) was mounted on the HLM as a backup, but not used. Tubing was changed to 3/16″ in the arterial line in patients &lt;13 kg. A retrospective study with a total of 140 patients compared patients placed on cardiopulmonary bypass (CPB) with Biomedicus centrifugal pumps and KAVD (Centrifugal Group,n= 40) to those placed on CPB with roller pumps and gravity drainage (Roller Group,n= 100). Patients requiring extra-corporeal membrane oxygenation (ECMO)/cardio-pulmonary support (CPS) or undergoing a hybrid procedure were excluded. Re-operation or circulatory arrest patients were not excluded. Prime volumes decreased by 57% from 456 ± 34 mL in the Centrifugal Group to 197 ± 34 mL in the Roller Group (p&lt; .001). There was a corresponding increase in hematocrit (HCT) of blood primes and also on CPB. Intraoperative homologous blood transfusions also decreased 55% from 422 mL in the Centrifugal Group to 231 mL in the Roller Group (p&lt; .001). The Society of Thoracic Surgeons--European Association for Cardio-Thoracic Surgery (STAT) categorized intubation times and hospital length of stay (LOS) for all infants showed a trend toward reduction, but was not statistically significant. Overall mortality was 5% utilizing the centrifugal configuration and 0% in the roller pump cohort. We demonstrated that the transition to roller pumps in the arterial position of the HLM considerably reduced our priming volume and formed a basis for a comprehensive blood conservation program. By maintaining higher HCTs on CPB, we were able to reduce intraoperative homologous blood transfusions.

A New Venous Drainage Technique in Minimally Invasive Redo Tricuspid Surgery: Vacuum-Assist Venous Drainage via a Single Femoral Venous Cannula.

To summarise the experiences of applying vacuum-assist with a single femoral venous cannula drainage technique in minimally invasive isolated redo tricuspid surgery. Eight consecutive patients underwent minimally invasive redo tricuspid surgery through a right thoracotomy at our institute. All of the patients had isolated significant tricuspid regurgitation after previous cardiac surgeries, and received minimally invasive redo tricuspid surgery. The arterial cannula was inserted into the femoral artery, and at the same time, the venous cannula was placed into the femoral vein. The venous cannula was guided by transoesophageal echocardiography and reached the superior vena cava (SVC). The caval veins did not need to be snared with the heart beating during the operation, but applying the vacuum-assisted venous drainage (VAVD) controller was necessary. This cannulation makes it possible to achieve adequate drainage (3.48±0.44L/min) and accomplishes complete arterial perfusion. Most importantly, it guarantees a good visual field without blood and allows safe surgery. The average time of cardiopulmonary bypass (CPB) was 68.25±13.84min. The length of ICU and hospital stays were 4.13 ±3.52 days and 8.14±4.98 days, respectively. In eight patients, there was no early death in the hospital. One patient experienced acute renal dysfunction. Vacuum-assist venous drainage via a single femoral venous cannula in isolated redo tricuspid surgery is safe, effective, reliable, and significantly simplifies the procedure.

Clinical application of modified minimally cardiopulmonary bypass: compared with conventional cardiopulmonary bypass

To evaluate the safety and effects on blood transfusion of modified minimally cardiopulmonary bypass (CPB). From April 2013 to February 2016, 1 103 elective cardiac surgery cases in National Center for Cardiovascular Diseases China, Fuwai Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College were prospectively enrolled in the study. Patients undergoing modified minimally CPB were assigned to mini-CPB group (n=553), the others undergoing conventional CPB were assigned to conventional group (n=550). In mini-CPB group, oxygenator with integrated arterial filter, modified minimized circuit, mini-cardioplegia and vacuum assisted venous drainage(VAVD) were used. In conventional group, conventional CPB was composed with conventional oxygenator from the same manufactory, conventional circuit and 1∶4 blood cardioplegia. Analysis was performed with t test, t' test, Wilcoxon rank-sum test, χ(2) test, and Fisher exact test. No CPB accidents and peri-operative stroke were observed. There was no statistical difference in postoperative mechanical ventilation time, length of ICU stay, postoperative complications and mortality between the two groups. The incidence of erythrocyte transfusion (13.7% vs. 27.6%, χ(2)=32.458, P=0.000) and the incidence of ultrafilter (11.0% vs. 33.7%, χ(2)=76.019, P=0.000) were lower in the mini-CPB group. Postoperative hematocrit (M(QR): 32.9 (5.7) vs. 32.2 (5.7), Z=3.403, P=0.001) and 12-hour chest drainage ((228±154) ml vs.(260±197) ml, t'=3.004, P=0.003) of mini-CPB were imporved compared with conventional group. Modified minimally CPB is safe. It might reduce erythrocyte transfusion for adult cardiac surgery, warranting widely adoption.

VAVD vacuum may cause bubble transgression in membrane oxygenators.

Vacuum-assisted venous drainage (VAVD) is widely used to enhance venous blood return from patients undergoing cardiopulmonary bypass (CPB). This vacuum can accidentally reach the oxygenator of the heart-lung machine and draw gas bubbles into the blood. This is known as bubble transgression (BT) and may cause air emboli in the arterial blood line. In order to avoid BT and minimize the risk of patient injury, knowledge of oxygenator tolerance to vacuum load is critical. Thus, the main aim of this thesis was to investigate how much vacuum a membrane oxygenator can withstand before BT appears. We investigated four different adult oxygenators: Quadrox-i, Affinity Fusion, Capiox RX25 and Inspire 6M. They were tested in an in vitro setup where VAVD vacuum was allowed to reach the oxygenator through a non-occlusive roller pump. An ultrasonic clinical bubble counter, Gampt BCC 200, was used to count bubbles on the arterial line when the arterial pump was restarted. We observed a significant increase in bubble count for two of the oxygenators, caused by -30 mmHg of VAVD vacuum in the blood reservoir (Affinity Fusion and Inspire 6M). Massive air ingress was shown in two of the oxygenators, caused by -30 mmHg of VAVD vacuum in the reservoir (Capiox RX25) and -40 mmHg of VAVD vacuum in the reservoir (Affinity Fusion). VAVD vacuum may cause bubble transgression in an oxygenator. This was shown for all the oxygenators in this test. VAVD vacuum may cause visible massive air ingress in an oxygenator. This was shown for two of the oxygenators in this test (Capiox RX25 and Affinity Fusion). An alarm triggering on negative pressure in the oxygenator or a pressure relief valve might improve safety when using VAVD.

Versatile minimized system--a step towards safe perfusion.

A growing body of evidence indicates the superiority of minimized cardiopulmonary bypass (CPB) systems compared to conventional systems in terms of inflammatory reactions and transfusion requirements. Evident benefits of minimized CPB systems, however, do not come without consequences. Kinetic-assisted drainage, as used in these circuits, can result in severe fluctuations of venous line pressures and, consequently, fluctuation of the blood flow delivered to the patient. Furthermore, subatmospheric venous line pressures can cause gaseous microemboli. Another limitation is the absence of cardiotomy suction, which can lead to excessive blood loss via a cell saver. The most serious limitation of minimized circuits is that these circuits are very constrained in the case of complications or changing of the surgery plan. We developed a versatile minimized system (VMS) with a priming volume of about 600 ml. A compliance chamber in the venous line decreases peaks of pressure fluctuations. This chamber also acts as a bubble trap. Additionally, the open venous reservoir is connected parallel to the venous line and excluded from the circulation during an uncomplicated CPB. This reservoir can be included in the circulation via a roller pump and be used as a cardiotomy reservoir. The amount and rate of returned blood in the circulation is regulated by a movable level detector. Further, the circuit can easily be converted to an open system with vacuum-assisted venous drainage in the case of unexpected complications. The VMS combines the benefits of minimized circuits with the versatility and safety of a conventional CPB system. Perfusionists familiar with this system can secure an adequate and timely response at expected and unexpected intraoperative complications.

Vacuum-Assisted Venous Drainage: A 2014 Safety Survey

Despite the widespread use of vacuum-assisted venous drainage (VAVD) and case reports describing catastrophic incidents related to VAVD, there is a lack of data cataloging specific safety measures that individuals and institutions have incorporated into their VAVD practices for the prevention of these incidents. Therefore, the purpose of this study is to survey the perfusion community to gather data on VAVD practices, and to compare these current practices with literature recommendations and the American Society of ExtraCorporeal Technology (AmSECT) Standards and Guidelines. In September 2014, a survey was distributed via PerfList and PerfMail, and by direct e-mail to members of the New York State Society of Perfusionists, targeting certified clinical perfusionists in New York State. Survey topics pertaining to VAVD practice included 1) equipment, 2) pressure monitoring and alarms, 3) protocols, checklists, and documentation, and 4) VAVD-related incidents. Of ∼200 certified clinical perfusionists who live and/or work in New York State (NYS), 88 responded (42%). Most respondents (90.1%) report they use VAVD. Of these, 87.3% report that they monitor VAVD pressure, with 51.6% having audible and visual alarms for both positive and excessive negative pressures. At the institutional level, 61.2% of respondents reported that there is a protocol in place at for their team limiting negative pressure in the reservoir, 28.4% document VAVD pressure in the pump record, and AmSECT’s three recommended VAVD checklist items are met with 53.7%, 55.1%, and 33.8% compliance. In conclusion, the results of this study reveal that the use of VAVD has increased and has become nearly universal in 2014. There is high compliance to some of the literature recommendations and AmSECT Standards and Guidelines, however, there are still some gaps between current practices and these recommendations. Continued improvement, both at the individual and institutional levels, will help to improve patient safety by preventing untoward events from occurring while using VAVD.