Perfusion

Cell saving systems are commonly used during cardiac operations to improve hemoglobin levels and to reduce blood product requirements. We analyzed the effects of residual pump blood salvage through a cell saver on coagulation and fibrinolysis activation and on postoperative hemoglobin levels. Thirty-four elective coronary artery bypass graft (CABG) patients were randomized. In 17 patients, residual cardiopulmonary bypass (CPB) circuit blood was transfused after the cell saving procedure (cell salvage group). In the other 17 patients, residual CPB circuit blood was discarded (control group). Activation of the coagulative, fibrinolytic and inflammatory systems was evaluated pre-operatively (Pre), 2 hours after the termination of CPB (T0) and 24 hours postoperatively (T1), measuring prothrombin fragment 1.2 (PF 1.2), plasmin-anti-plasmin (PAP), plasminogen activator inhibitor-1 (PAI-1) and interleukin-6 (IL-6). The cell salvage group of patients had a significant improvement in hemoglobin levels after processed blood infusion (2.7 ± 1.7 g/dL vs 1.2 ± 1.1 g/dL; p=0.003). PF1.2 levels were significantly higher after infusion (T0: 1175 ± 770 pmol/L vs 730 ± 237 pmol/L; p=0.037; T1: 331 ± 235 pmol/L vs 174 ± 134 pmol/L; p=0.026). Also, PAP levels were higher in the cell salvage group, although not significantly (T0: 253 ± 251 ng/mL vs 168 ± 96 ng/mL; p: NS; T1: 95 ± 60 ng/mL vs 53 ± 32 ng/mL; p: NS). No differences were found for PAI-1, IL-6, heparin levels or for red blood cell (RBC) transfusions. The cell salvage group of patients had increased chest tube drainage (749 ± 320 vs 592 ± 264; p: NS) and fresh frozen plasma transfusion rate (5 (29%) pts vs 0 pts; p<0.04). Pump blood salvage with a cell saving system improved postoperative hemoglobin levels, but induced a strong thrombin generation, fibrinolysis activation and lower fibrinolysis inhibition. These conditions could generate a consumption coagulopathy.

The performance of the Sorin Xtra® Autotransfusion System (ATS) was studied in 62 patients undergoing coronary artery bypass grafting. Blood was collected intraoperatively and washed using three different wash sets in 4 groups. Both collected and washed blood were analysed for hemoglobin levels and hematocrit, concentrations of proteins, albumin, heparin and plasma free hemoglobin (PFH) were determined, erythrocytes, platelets and leukocytes were counted.

Hematocrit measurements of the Xtra® were compared with laboratory measurements to study the accuracy of the Xtra® hematocrit sensor. In addition, the red blood cell recovery rate and elimination rates were calculated to evaluate the clinical performance of the Xtra®.

The Xtra® ATS produced a volume of concentrated red blood cells with an average hematocrit from 58% to 63%, depending on the size of the bowl and the chosen default program. In all bowl sizes and programs, the Xtra® Hct-out measurement underestimated the CELL-DYN measurement by approximately 15%.

The calculated recovery rates for red blood cells (RBC) in the 4 groups ranged from 86.7% to 91.6%. Elimination rates were calculated in each group for proteins (96.8-99.2%), albumin (96.4-98.7%), plasma free hemoglobin (83.6–91.2%), heparin (98.8-99.9%), platelets (82.4-94.3%) and white blood cells (28.6-42.3%).

The Xtra® ATS can be appealing for its performance by producing high hematocrit levels in the washed RBC volume, while keeping RBC recovery rate at the same high level (≈ 90%) as in its predecessor, the Electa® Autotransfusion System.

We evaluated the influence of methylprednisolone in cardiopulmonary bypass fluid on scavenger receptor for hemoglobin CD163 molecule expression on monocytes of patients who underwent elective coronary artery bypass grafting with cardiopulmonary bypass with either exposure to methylprednisolone present in the cardiopulmonary bypass fluid (20 patients), or without methylprednisolone in the cardiopulmonary bypass fluid (22 patients) and operated on without cardiopulmonary bypass (42 patients). The dynamics of CD163 expression was also followed in patients operated on without cardiopulmonary bypass. This study was a retrospective analysis of a comparison of two studies. The expression of CD163 was determined quantitatively by standardized flow cytometry technique. The similarities in the dynamics of CD163 monocyte expression, comparing the patients operated on with or without cardiopulmonary bypass, were found. Compared to the preoperative level, CD163 monocyte expression was significantly elevated on the 1^st postoperative day. Monocyte CD163 expression on the 1^st postoperative day was evidently similar in both groups of patients operated without cardiopulmonary bypass (median value of mean fluorescence intensity (MFI) 18,896; interquartile range from 27,538 to 57,711; median value of MFI 18,863; interquartile range from 16,514 to 26,559; n.s.), suggesting high reproducibility of our flow cytometric method; the monocyte CD163 expression was significantly higher (median value of MFI 37,902; interquartile range from 27,538 to 57,711) on the 1^st postoperative day in patients exposed to methylprednisolone compared to patients without this exposure (median value of MFI 20,995; interquartile range from 16,321 to 29,623) (p<0.001).

We concluded that the expression of hemoglobin scavenger receptor CD163 on monocytes of cardiac surgical patients is induced by methylprednisolone present in cardiopulmonary bypass fluid.

Plasma clearance of indocyanine green has recently been established as a tool to monitor hepatic function and perfusion non-invasively. Reduced indocyanine green clearance has been associated with adverse outcome in cardiac surgery patients, and cardiopulmonary bypass has been hypothesized to be one important triggering factor. We performed a prospective observational study comparing the influence of off-pump and on-pump coronary surgery on perioperative indocyanine green clearance. Twenty-five consecutive adult patients without known pre-existing hepatic diseases scheduled for off-pump coronary artery bypass grafting were evaluated for hepatic dysfunction pre- and postoperatively with serial measurements of indocyanine green plasma clearance, specific laboratory values and liver function scores. Twenty-five matched patients who underwent coronary artery bypass grafting surgery with cardiopulmonary bypass in the same period served as controls. Parameters of postoperative hepatic function, including measurements of indocyanine green plasma clearance and specific laboratory values and scores, did not differ significantly between patients undergoing off-pump coronary artery bypass grafting and patients undergoing coronary artery bypass grafting with extracorporeal circulation. In patients without pre-existing hepatic diseases, a significant influence of cardiopulmonary bypass on perioperative indocyanine green plasma clearance as well as on liver specific laboratory parameters and scores cannot be proven.

Anecdotally, fibrinogen concentrate (FC) has been used as a “universal” haemostatic agent in complex post-cardiopulmonary bypass (CPB) coagulopathy. We present a case where FC and two pools of platelets prevented life-threatening bleeding in a patient with moderate von Willebrand Disease (vWD) immediately post CPB.

The application of peripheral veno-arterial extracorporeal membrane oxygenation in the management of inotrope-refractory cardiogenic shock has proven controversial because of concerns about sub-optimal drainage of the left heart, resulting in left ventricular distension and pulmonary oedema. In this article, we will discuss the pathophysiological basis and clinical implications of left ventricular distension following institution of peripheral extracorporeal life support. We will also review the clinical strategies used to circumvent left ventricular distension and pulmonary oedema in these patients.

A previously healthy 60-year-old male presented with fever, general pain and a C-reactive protein (CRP) of 160 mg/L. He was prescribed doxycycline. In the emergency room three days later, he was intubated and had a saturation of 70% on 100% oxygen. The chest X-ray showed bilateral lobar pneumonia. Streptococcus pneumonia was later verified.

As a Jehovah’s Witness, he had refused blood transfusions, but accepted albumin. Two days after admission, veno-venous extracorporeal membrane oxygenation (V-V ECMO) was started and the patient was then transported on ECMO to Stockholm. After two days, echocardiography showed right cardiac failure and the patient had to be converted to veno-arterial ECMO (VV-A ECMO) by cannulation of the left femoral artery. The haemoglobin decreased from 10.0 to 6.0 g/dL. Iron, folic acid, and erythropoietin were administered to stimulate erythropoesis. Romiplostim, to stimulate the production of platelets, was also started immediately. Blood samples were reduced to a minimum. The ECMO circuit was changed twice, using saline for priming, and the blood in the old circuit was then given back to the patient. The haemoglobin concentration varied between 4.5 and 6.0 g/dL during the ECMO treatment and the platelets between 80 and 140 x10⁹/L.

After 44 days on ECMO, the patient was weaned off ECMO with 50% oxygen and nitric oxide (NO) at 20ppm in the ventilator. Four days after decannulation, he was transferred to a nearby intensive care unit.

Long-term ECMO treatment without transfusion of blood products is possible. Being a Jehovah’s Witness should not automatically be a contraindication for ECMO.

Extracorporeal membrane oxygenation (ECMO) is increasingly being used in patients with severe acute respiratory distress syndrome. In two large cohorts of such patients, the median duration of treatment with ECMO was 9 and 10 days.

We describe two patients, both with H1N1 pneumonia complicated by invasive Aspergillosis, who required ECMO support significantly longer at 45 and 52 days, but eventually made a full recovery. In both patients, prone positioning was used during ECMO treatment.

The ideal location of air bubble detector (ABD) placement on the cardiopulmonary bypass (CPB) circuit is debatable. There is, however, very little data characterizing the prevalence of specific ABD placement preferences by perfusionists. Therefore, the purpose of this study was to survey the perfusion community to collect data describing the primary locations of air bubble detector placement on the CPB circuit.

In June 2011, an 18-question on-line survey was conducted. Completed surveys were received from 627 participants. Of these, analysis of the responses from the 559 certified clinical perfusionists (CCP) was performed.

The routine use of ABD during CPB was reported by 96.8% of CCPs. Of this group, specific placement of the bubble detector is as follows: distal to the venous reservoir outlet (35.6%), between the arterial pump and oxygenator (3.8%), between the oxygenator and arterial line filter (35.1%), distal to the arterial line filter (ALF) (23.6%), and other (1.8%). Those placing the ABD distal to the venous reservoir predominately argued that an emptied venous reservoir was the most likely place to introduce air into the circuit. Those who placed the ABD between the oxygenator and the arterial line filter commonly reasoned that this placement protects against air exiting the membrane. Those placing the ABD distal to the ALF (23.6%) cited that this location protects from all possible entry points of air. A recent false alarm event from an ABD during a case was reported by 36.1% of CCPs.

This study demonstrates that the majority of CCPs use an ABD during the conduct of CPB. The placement of the ABD on the circuit, however, is highly variable across the perfusion community. A strong rationale for the various ABD placements suggests that the adoption of multiple ABD may offer the greatest comprehensive protection against air emboli.