Assessing the effectiveness of retrograde autologous priming of the cardiopulmonary bypass machine in isolated coronary artery bypass grafts.

INTRODUCTION: Currently, around 35-80% of patients undergoing cardiac surgery in the UK receive a blood transfusion. Retrograde autologous priming (RAP) of the cardiopulmonary bypass circuit has been suggested as a possible strategy to reduce blood transfusion during cardiac surgery. METHODS: Data from 101 consecutive patients undergoing isolated coronary artery bypass grafts (where RAP was used) were collected prospectively and compared with 92 historic patients prior to RAP use in our centre. RESULTS: Baseline characteristics (ie age, preoperative haemoglobin [Hb] etc) were not significantly different between the RAP and non-RAP groups. The mean pump priming volume of 1,013ml in the RAP group was significantly lower (p<0.001) than that of 2,450ml in the non-RAP group. The mean Hb level at initiation of bypass of 9.1g/dl in patients having RAP was significantly higher (p<0.001) than that of 7.7g/dl in those who did not have RAP. There was no significant difference between the RAP and non-RAP groups in transfusion of red cells, platelets and fresh frozen plasma, 30-day mortality, re-exploration rate and predischarge Hb level. The median durations of cardiac intensive care unit stay and in-hospital stay of 1 day (inter-quartile range [IQR]: 1-2 days) and 5 days (IQR: 4-6 days) in the RAP group were significantly shorter than those of the non-RAP group (2 days [IQR: 1-3 days] and 6 days [IQR: 5-9 days]). CONCLUSIONS: In the population group studied, RAP did not influence blood transfusion rates but was associated with a reduction in duration of hospital stay.

Autotransfusion system or integrated automatic suction device in minimized extracorporeal circulation: influence on coagulation and inflammatory response.

OBJECTIVE: To measure surrogate markers of coagulation activation as well as of the systemic inflammatory response in patients undergoing primary elective coronary artery bypass grafting (CABG) using either the so-called Smart suction device or a continuous autotransfusion system (C.A.T.S.®). METHODS: Fifty-eight patients being operated with a miniaturized circuit (minimal extracorporeal circuit, MECC) were prospectively randomized to using a so-called Smart suction device or a routine continuous autotransfusion system (C.A.T.S.®) for collection of mediastinal shed blood. The coagulation response was measured by thrombin-antithrombin complex (TAT) and D-dimer. The inflammatory response was measured by Interleukin 6 (IL-6) and complement factor 3a (C3a) at three different time points, before surgery, 2h after surgery, as well as 18 h after surgery. RESULTS: No serious adverse cardiovascular event was observed. Serum levels of TAT significantly differed between both groups 2h after surgery (Smart suction 16.12 ± 13.51 µg l⁻¹ vs C.A.T.S® 9.83 ± 7.81 µg l⁻¹, p = 0.040) and returned to baseline values after 18 h in both groups. Serum levels of D-dimer showed a corresponding pattern with a peak 2h after surgery (Smart suction 1115 ± 1231 ng ml⁻¹ vs C.A.T.S.® 507 ± 604 ng ml⁻¹, p = 0.025). IL-6 levels also significantly differed between both groups 2h after surgery (Smart suction 186 ± 306 pg ml⁻¹ vs C.A.T.S.® 82 ± 71 pg ml⁻¹, p = 0.072). No significant changes in serum levels of C3a over time could be observed. CONCLUSIONS: Despite no differences in the clinical course of patients with either Smart suction or C.A.T.S.® being observed, surrogate markers of coagulation and inflammation seem to be less pronounced in patients where cardiotomy blood is not being directly reinfused. As such, C.A.T.S.® should be preferred in routine CABG, as long as no extensive volume substitution is anticipated.

Circulating particles during cardiac surgery.

Shed blood is known to be a source of lipid micro-emboli in cardiac surgery. The aim of this study was to characterize the occurrence of these particles at different stages of the operation, and to study their occurrence in the circulation at multiple time-points after the retransfusion of shed blood. Forty-four patients undergoing routine surgery with cardiopulmonary bypass were included. Blood was sampled from the surgical field at different sampling locations during the operation. Shed blood was collected in a transfusion bag and retransfused. After which, blood was sampled from the arterial line of the heart-lung machine. A Coulter counter was used for particle determinion. The mean volume of shed blood collected was 340+/-215 ml. Particles in the size range 10-60 microm were found at varying concentrations, with the highest concentrations being found in blood collected after cannulation and from the pleura. After retransfusion of this blood, a biphasic response was seen in the blood drawn from the efferent line of the heart-lung machine. Particles are found in shed blood at all times during cardiac surgery, and when this blood was retransfused an increase was seen in particle concentration in the heart-lung machine.

Clinical advantages of using mini-bypass systems in terms of blood product use, postoperative bleeding and air entrainment: an in vivo clinical perspective.

OBJECTIVE: In an effort to minimize the effect of extracorporeal circulation (ECC), mini-bypass is gaining clinical acceptance in routine coronary artery bypass grafting (CABG). These small circuits target combine the clinical advantages of reduced prime, 100% bio-coating and suction blood separation. We demonstrate that the use of mini-bypass in routine CABG reduces homologous blood product use and postoperative bleeding. Our goal was to also demonstrate that these small systems are effective in gaseous microemboli (GME) management as compared to a conventional extracorporeal system. METHODS: Prospective, randomized study comparing 30 mini-bypass (Dideco ECC.O) to 30 conventional systems (n=30, Dideco 903 Avant). Study included CABG cases only, independent of preoperative coagulative status; clinic ethical committee approval and informed patient consent was obtained before initiating study. RESULTS: There were no statistical differences in terms of patient demographics. Statistically significant differences were seen in transfusion frequency (27% of the study group vs 43% in the control group, p=0.05), transfused volume (133.3+/-244.5 ml vs 325+/-483.1 ml, p<0.05), fresh frozen plasma (0 unit vs 3 units, p<0.001), postoperative bleeding (301.8+/-531.9 ml vs 785.5+/-1000.4 ml, p<0.05) and GME activity post-arterial filter (0.14 microl vs 5.32 microl, p<0.05). CONCLUSIONS: The adoption of mini-bypass significantly potentially reduces hemodilution, donor blood usage, postoperative bleeding and exposure to GME in routine CABG patients as compared to the use of conventional extracorporeal circulation circuits.

Comparison of two pain-management strategies during chest tube removal: relaxation exercise with opioids and opioids alone.

PURPOSE: The purpose of this study was to determine whether the use of a slow deep-breathing relaxation exercise, when used as an adjunct to opioid analgesia, decreases pain during chest tube removal (CTR) after coronary bypass surgery. DESIGN: A two-group quasi-experimental pretest/posttest design was used. SAMPLE: A convenience sample of 40 adults who had undergone coronary artery bypass graft surgery and met all inclusion criteria were recruited before CTR. SETTING: Data were collected in the Cardiothoracic Surgical Intensive Care Units of three acute care facilities in the Midwestern United States. METHOD: A 10-cm vertical Visual Analog Scale was used to measure pain at three points: before CTR, immediately after CTR, and 15 minutes after CTR. The experimental group received slow breathing relaxation exercises in addition to the usual opioid doses administered. FINDINGS: Data were analyzed using analysis of variance, and multivariate analysis of covariance yielded a significant difference in pain ratings immediately after CTR and 15 minutes after CTR for the group receiving relaxation exercise as an adjunct to opioid analgesic. CONCLUSIONS: This study supports the use of a slow deep-breathing relaxation exercise as an adjunct to the use of opioids for pain management during CTR among patients who have undergone coronary bypass surgery.

Coronary artery bypass with the use of a magnetic distal anastomotic device: surgical technique and preliminary experience.

BACKGROUND: At present there is little reported experience in the application of new technology in the performance of distal coronary anastomoses in the clinical setting. The aim of our study was to evaluate the feasibility of using the Ventrica magnetic vascular positioner (MVP) device for left internal thoracic artery (LITA)-to-left anterior descending (LAD) coronary anastomosis. METHODS: We present our preliminary experience of the first 14 coronary artery cases performed in the United Kingdom from April 2003 to December 2003. The selection criteria, surgical technique, clinical outcome, advantages or disadvantages, and future implications are all discussed. RESULTS: The device was used in 12 patients for LITA-to-LAD anastomosis and in 2 patients for the proximal anastomosis of a radial artery Y-graft from the LITA to the circumflex territories. The first 3 patients underwent coronary artery bypass graft with the use of cardiopulmonary bypass, and the remaining 9 underwent surgery performed using an off-pump coronary artery bypass technique. No mortality or device-related events were observed in these patients. The anastomosis time in our series was 5.6 +/- 1.99 minutes, and the blood loss was 914 +/- 234 mL. The mean length of stay was 5.8 +/- 1.16 days. CONCLUSION: The MVP system is a novel distal coronary anastomotic device that is quick, simple, and effective, producing consistently reliable coronary anastomoses in a wide variety of coronary bypass procedures. Early results are encouraging, and further studies are required in order to evaluate long-term efficacy of this system in the rapidly changing world of coronary revascularization.

Retrograde autologous prime with shortened bypass circuits decreases blood transfusion in high-risk coronary artery surgery patients.

Previous studies have shown that minimizing the amount of hemodilution during open-heart surgery reduces the need for a blood transfusion. Transfusion increases a patient's medical risks and leads to increased costs. We used a shortened bypass circuit, primed with autologous blood in a retrograde fashion, to decrease red cell transfusion in high-risk patients. One hundred twenty-three patients having first-time, nonemergent coronary artery surgery were chosen for this trial, based on their low prebypass hematocrit and weight. In seventy-two cases, we used a shortened bypass circuit and retrograde autologous prime. A historical control group of fifty-one patients received a standard bypass circuit and prime method. The prebypass hematocrit was 35 +/- 2.62% and 34 +/- 2.99% in the control and study groups, respectively. Red blood cell transfusion was necessary in 70% of the control group during their hospital stay, whereas only 51.4% of the study group required transfusion (p = .006). Patients receiving no blood products were significantly higher in the study group, 48.6% vs. 30.0% (p = .005). The postbypass hematocrit was similar at 26.5 +/- 1.82% vs. 25.5 +/- 2.38%, and the discharge hematocrit was 30.8 +/- 3.33% and 31.2 +/- 3.04% in the control and study groups. respectively. Minimizing hemodilution by shortening the bypass circuit and performing retrograde autologous prime conserves the use of blood during routine coronary artery bypass surgery. These methods can be used for patients who are at greater risk for transfusion.

[Telemanipulatory application of a magnetic coupler on the beating heart with the daVinci surgical system]. / Telemanipulator-gestützte Applikation eines magnetischen Gefäss-Kopplers am schlagenden Herzen mit dem da Vinci-Surgical-System.

The construction of a coronary anastomosis on the beating heart under totally endoscopic conditions is technically demanding. In this study the potential benefits of an endoscopic magnetic vascular coupler (MVP, Ventrica, Inc, Fremont, CA) designed to facilitate construction of a coronary anastomosis with the help of the daVinci telemanipulator (Intuitive Surgical Inc., Sunnyvale, CA) were evaluated in a totally endoscopic coronary arterial bypass (TECAB) operation on the beating heart in eight dogs. The telemanipulated instruments were used to guide and place the endoscopic MVP-application platform (prototype). All animals underwent angiography, and gross inspection of the anastomotic site was done after excision of the hearts. The procedure was accomplished in 169 minutes (155-190). With the exception of one premature deployment, all MVP-anastomoses were accomplished in 3 minutes (1-28). The following adverse events were encountered: Bleeding from the right ventricle caused by occlusion tape (1), anastomotic leakage upon reperfusion requiring repair stitches (2), anastomotic occlusion due to a thrombus (1). All but one animal that died on reperfusion despite a patent graft and anastomosis, survived the procedure. Overall patency was 7 out of 8. The combination of telemanipulator technology allowing increased manipulation dexterity in a total endoscopic environment and the effective and time saving magnetic technique for anastomotic coupling has the potential to facilitate TECAB on the beating heart.

An atraumatic aspirator for use in autologous transfusion and cardiac bypass.

Surgical aspiration has long been seen as the weak link in surgical blood recovery. Aspiration causes a high degree of hemolysis that leads to high plasma hemoglobin levels and reduces the number of erythrocytes available for reinfusion. Aspiration also damages platelets, generates emboli, and increases bleeding time. The major source of the high hemolysis and the other blood damage that occurs during suction is the aspiration of air with the blood. To address this problem, a jet driven aspirator that immediately separates and removes air during suction was designed and tested. The aspirator suctions blood at a range of rates from 100 to at least 700 ml/min, separates and removes 80-100% of the aspirated air, operates at any orientation, and generates subatmospheric pressures on the order of only an inch of water. During in vitro hemolysis testing, the removal of air by the jet driven aspirator showed a significant reduction in hemolysis: plasma hemoglobin levels increased 19.4 mg/dl without air removal and only 1.8 mg/dl with air removal (p < 0.001). In comparative testing with a conventional vacuum operated suction tube, the jet driven aspirator showed significantly less hemolysis (p < 0.001) than did the conventional aspirator at comparable blood and air aspiration rates.

[Retransfusion of thoracic drainage blood: qualitative analysis]. / Retransfusion des Thoraxdrainageblutes: qualitative Analyse.

In a prospective randomized study 10 patients received their shed mediastinal blood after elective coronary artery bypass surgery and were compared to 10 control patients without retransfusion. The quality assessment can be summarized as follows (mean +/- 1 SD): 1. Hemoglobin concentration of the shed blood was 9.6 +/- 1.45 g/dl. 2. The energy rich phosphate compounds of the shed blood erythrocytes were 2.6 +/- 0.8 mumol/gHb ATP (70% of the patients preoperative value) and 14.8 +/- 4.2 mumol/gHb 2.3-DPG (normal). 3. Proteins, immunoglobulins and especially albumin in the shed blood were not significantly different from the patients own values. 4. No electrolyte changes, safe for a slight increase in potassium (5.7 +/- 0.7 mmol/l). 5. The activated clotting time of the patient did not change during retransfusion. 7. Plasma free hemoglobin was elevated to 211.1 +/- 44.3 mg/dl in the shed blood; however, no significant increase could be noted in the retransfused patients and no hemoglobinuria occurred. Postoperative retransfusion of shed mediastinal blood is a simple and safe method of autologous transfusion early after cardiac surgery and should be combined with other methods of blood salvage. The qualitative advantages of blood retransfusion consist in the absence of storage damage and in the preservation of autologous proteins and immunoglobulins.

Complement activation and use of a cell saver in cardiopulmonary bypass.

Complement activation was evaluated in ten patients undergoing cardiopulmonary bypass (CPB) and intraoperative blood salvage with a cell saver (CS) to assess the inflammatory response related to the CS. The washed red blood cell concentrate was reinfused after protamine injection. Plasma C3a was measured by radioimmunoassay preoperatively, 5 min before CPB, at 5, 60, and 90 min during CPB, 5 min after protamine infusion, at the end of surgery, and after 24 hr. In addition, a clinical score based on renal, pulmonary, neurologic, and myocardial postoperative evolution was given (0-8) to every patient. Results were compared with the C3a changes and clinical scores obtained from 26 routine (no CS) cardiac surgical patients. Results showed maximal C3a generation after protamine and no further activation in cases of CS concentrate reinfusion, which ranged from 400 ml to 2,000 ml. No difference in clinical score was observed between the CS (1 +/- 1) and control (0.85 +/- 0.6) groups. The authors conclude that the CS does not enhance complement activation resulting from extracorporeal circulation and can be safely used as a blood saving strategy in cardiac surgery.

Acute and chronic traumatic aneurysms of the descending thoracic aorta: a 10-year experience with a single method of aortic shunting.

A 10-year experience in the surgical treatment of traumatic aneurysms of the descending thoracic aorta is reviewed. This series included 40 patients equally divided into two groups. Group I comprised 20 acute ruptures and group II, 20 chronic traumatic aneurysms, all situated at the aortic isthmus. The surgical repair was performed in all patients with a single method of aortic shunting. A Gott aneurysm shunt was used as a temporary external bypass between the ascending and the descending aorta, giving priority to organ protection during aortic cross-clamping. The survival rate was 95% (38/40). The two deaths occurred in the acute group and were related to severe brain trauma present before surgery. The aortic cross-clamping time averaged 43 minutes. Regarding organ protection, no brain damage, no heart failure, no renal dysfunction, and no paraplegia occurred. These results emphasize the safety and the reliability of this shunting procedure.