Staffan Svenmarker

The inflammatory response to recycled pericardial suction blood and the influence of cell-saving

Objective--To investigate the inflammatory and cellular response attributed to conventional cardiotomy suction vs cell-saver during cardiac surgery. Design--Thirty-three (n = 33) low-risk patients admitted for routine coronary artery bypass grafting were randomly assigned to two groups: cardiotomy suction or cell-saver for salvage of pericardial blood. The groups were compared with reference to proinflammatory cytokines, complement activation, leukocyte pattern, and haemolysis during and after cardiopulmonary bypass. Results--Pericardial suction blood contained significantly increased concentrations of free plasma haemoglobin, C3a, IL-6, IL-8, TNF-α, eosinophils and basophils compared with the systemic circulation. No differences were found for the terminal complement complex and lymphocytes, whereas overall concentrations of leukocytes, platelets and haemoglobin were decreased. Recycling of pericardial suction blood gave no systemic effects except from that of free plasma haemoglobin, which increased significantly. The cell-saver eliminated plasma haemoglobin, but no other effects could be demonstrated. Conclusion--Cardiotomy suction is a major cause of haemolysis, but contributes insignificantly to the systemic inflammatory response. Treatment of shed mediastinal blood with a cell-saver reduces haemolysis and may lower the dose load of inflammatory components.

Clinical effects of the heparin coated surface in cardiopulmonary bypass

OBJECTIVE In a randomised study of 120 patients, undergoing primary operation for coronary heart decease, two groups were investigated as regards to the effects of heparin coated cardiopulmonary bypass on brain function parameters and general clinical outcome. The study group (n = 56) was perfused using an extra-corporeal circuit treated with covalent bonded heparin; the control group (n = 59) used an identical set-up without heparin treatment. Systemic heparin doses were calculated to achieve ACT levels of 250 and 500 s, respectively. Postoperative course was evaluated by examining a set of clinically relevant parameters including a detailed registry of postoperative deviations. Brain function was assessed by the biochemical marker S-100 and tests of memory performance. RESULTS There were several signs of reduced operative trauma in the study group. Hospital stay was reduced by nearly 1 day (P < 0.05). Time on postoperative ventilatory support was approximately 4 h shorter (P = 0.009). Chest drain blood loss was decreased both at 8 (P = 0.01) and 24 h (P = 0.007) postoperatively. Body temperature was lower after surgery and especially on days 2 (P = 0.03) and 3 (P = 0.01). Perioperative creatinine elevation was significantly reduced (P = 0.03). Neurological deviations were fewer (P = 0.01). Brain function assessment revealed reduced plasma levels of S-100 both at termination of cardiopulmonary bypass (P = 0.008) and 7 h later (P = 0.04). However, no remediation of memory impairment could be demonstrated. CONCLUSIONS Cardiopulmonary bypass with covalent bonded heparin attached to the extra-corporeal circuit in combination with a reduced systemic heparin dose seems to reduce safely and effectively the operative stress to the patient. There were also signs of improved cerebral protection.

Use of heparin-bonded circuits in cardiopulmonary bypass improves clinical outcome.

Objective : The use of heparin-coated surfaces in cardiopulmonary bypass has been shown to decrease the inflammatory response imposed by the contact between blood and artificial surfaces. One would expect this reaction to improve clinical outcome. However, this has been difficult to verify. This investigation is based on an aggregation of two randomized studies from our institution and highlights possible effects of heparin coating on a number of clinically oriented parameters. Design : Departmental analysis of patients subjected to coronary artery bypass surgery using heparin-coated circuits. Cardiopulmonary bypass was employed using either the Carmeda or Duraflo heparin coatings compared with a control. The systemic heparin dose was reduced in the heparin-coated groups (ACT > 250 s) vs control group patients (ACT > 480 s). The effects of heparin coating related to clinical outcome were studied. Results : The use of heparin-coated circuits reduced the mean length of stay in hospital from 7.8 - 2.5 to 7.3 - 1.8 days ( p = 0.040) and postoperative ventilation time from 9.7 - 9.2 to 8.2 - 8.5 h ( p = 0.018), blood loss 8 h post surgery from 676 - 385 to 540 - 245 ml ( p = 0.001), individual perioperative change of haemoglobin loss ( p = 0.001), leukocyte count ( p = 0.000) and creatinine elevation ( p = 0.000), proportion of patients exposed to allogenous blood transfusions 39.2 vs 23.9% ( p = 0.001), postoperative coagulation disturbances 4.4 vs 0.4% ( p = 0.006), postoperative deviations from the normal postoperative course 47.2 vs 36.7% ( p = 0.035), neurological deviations 9.4 vs 3.9% ( p = 0.021) and atrial fibrillation 26.4 vs 18.0% ( p = 0.041). No effects were found with respect to perioperative platelet count, postoperative fever reaction and 5-year survival. Conclusion : Based on several indicators, the use of heparin coating in cardiopulmonary bypass is associated with improved clinical results.

Neurological and general outcome in low-risk coronary artery bypass patients using heparin coated circuits

OBJECTIVE The clinical significance of heparin coating in cardiopulmonary bypass has previously been investigated. However, few studies have addressed the possible influence on brain function and memory disturbances. METHODS Three hundred low-risk patients exposed to coronary bypass surgery were randomised into three groups according to type of heparin coating: Carmeda Bioactive Surface, Baxter Duraflo II and a control group. Outcome was determined from a number of clinically oriented parameters, including a detailed registry of postoperative deviations from the normal postoperative course. Brain damage was assessed through S100 release and memory tests, including a questionnaire follow-up. RESULTS Clinical outcome was similar for all groups. Blood loss (Duraflo only), transfusion requirements and postoperative creatinine elevation were reduced in the heparin-coated groups. A lower incidence of atrial fibrillation was noted in the Duraflo group. Heparin coating did not uniformly attenuate the release of S100 or the degree of memory impairment. CONCLUSIONS Cardiopulmonary bypass (CPB) with heparin coating and a reduced dose of heparin seems to be safe. Clinical outcome and neurological injury seem not to be associated with type of heparin coating used for CPB. However, blood loss and transfusion requirements may be reduced.

Medium-term survival and quality of life of Swedish octogenarians after open-heart surgery

OBJECTIVE Operative mortality after open-heart interventions in the octogenarian population is relatively well known. Less has been reported on the medium term survival and quality of life of this growing subgroup of patients. METHODS One hundred and eighty-three consecutive patients aged between 80 and 84 years when they underwent open-heart surgery between January 1995 and June 2000 were retrospectively analysed. The patients were followed up for 36 months as regards survival and compared, after matching for age and gender, to survival in the general Swedish population. The health-related quality of life (HRQOL) of surviving patients was assessed in February 2001 using the SWED-QUAL questionnaire. After matching for differences by age and gender, survival results were compared to Swedish national survival data, and functioning and well-being to the corresponding national norm data. Pre-, intra- and post-operative variables were evaluated as predictors for mortality, survival and quality of life. RESULTS The 30-day mortality rate was 4.6% (n = 8). The 36-month survival rate, that was 85.6%, did not differ significantly (P = 0.078) from that of a cohort of the Swedish population matched for age and gender. There was no significant difference in survival between male and female patients (P = 0.545). Systemic hypertension was the only variable found to be a statistically significant predictor of 36-month mortality (P = 0.009). As concerns HRQOL, patients had significantly better physical functioning, satisfaction with physical functioning, relief of pain and emotional well-being (P < 0.01) and similar quality of sleep (P = 0.106) as the normal population. Male patients and male normal population responders had similar HRQOL (P > 0.05) while female patients reported significantly better HRQOL than their population counterparts on all five dimensions (P < 0.01). CONCLUSIONS Patients 80-84 years of age may be operated on with acceptable operative mortality and benefit from improved functioning and well-being. Survival and quality of life after open-heart surgery among patients aged 80-84 years of age are comparable to, or even better than in the general Swedish population.

Is there an association between release of protein S100B during cardiopulmonary bypass and memory disturbances

Objective : The use of protein S100B as a marker of brain cell injury in conjunction with cardiopulmonary bypass (CPB) has recently been questioned. The present study investigates functional brain injury based on the relation between S100B and memory disturbances. Methods : Four hundred and fifteen low-risk coronary artery bypass patients exposed to CPB were examined. The protein S100B was sampled during and after surgery. Explicit and implicit memory function was assessed preoperatively and at discharge from hospital. Possible associations between the release of the protein S100B and memory function were studied. Results : Serum concentration of S100B peaked at termination of CPB (0.895 - 0.84 µ g/l) and decreased gradually; 7 h post CPB (0.436 - 0.59 µ g/l), day 1 (0.149 - 0.27 µ g/l) and day 2 (0.043 - 0.15 µ g/l). High levels of S100B (>1.5 µ g/l) 7 h post CPB were associated with a significant (-1 SD) decline of explicit memory function ( p = 0.006); this was not seen at termination of CPB ( p = 0.834). Predictors of memory decline were S100B 7 h post CPB, length of stay in hospital and concomitant neurological disorders. Postoperative S100B concentration was higher among patients with atrial fibrillation ( p = 0.022). Conclusion : Only high levels of protein S100B found 7 h post CPB were associated with decline of explicit memory function, not the release seen during CPB. Thus, when using protein S100B, only values several hours remote from surgery should be used as a brain cell injury marker.

Quality assurance in clinical perfusion

OBJECTIVE To investigate the properties and usefulness of prospective routine registration of incidents related to cardiopulmonary bypass and its clinical significance as a quality assurance instrument. METHODS Incidents or deviations from the normal course observed during cardiopulmonary bypass procedures were registered in a computer database. Each incident was classified according to 14 pre-defined categories. The cause of each incident was evaluated, as well as patient outcome. Incidents leading to permanent or temporary injury were denoted accidents. The general- and category-related incidence rate was calculated for the observation period 1989-1997 encompassing 6918 cardiopulmonary bypass procedures. RESULTS The general incidence rate varied between 4.5-7.6% per year during the registration period. Most incidents (57%) occurred during established, or start of, cardiopulmonary bypass, whereas the remaining proportion of incidents were detected either before (27%) or when terminating (16%). The most common category of incidents was oxygenator failure (1.6%), followed by mechanical (1.4%) and surgical (1.2%) incidents. Accidents and fatal outcomes occurred in 0.03% of the cases. CONCLUSIONS Routine registration of incidents yields a clinically attractive instrument of controlling safety aspects and quality measures in cardiopulmonary bypass. The observed incidence rates are somewhat higher than previously reported, probably primarily related to the methodology implemented in this study.

What is a normal lactate level during cardiopulmonary bypass

Blood lactate levels during cardiopulmonary bypass are often used to verify adequacy of perfusion. The present investigation aimed to propose a threshold for hyperlactatemia. Blood lactate levels in 5 121 cardiac surgical patients were retrospectively analysed by a review of database records. Hyperlactatemia was defined as a value equal to the 90th percentile of the identified lactate distribution at weaning from cardiopulmonary bypass. Patient demographics, background and outcome statistics were performed stratified on presence of hyperlactatemia. The threshold for hyperlactatemia was found to equal 2 mmol/l. Significant predictors of hyperlactatemia based on logistic regression modelling were age, complex surgery, duration of cardiopulmonary bypass, blood transfusion, acid base level, emergency operations, diabetes, vasoactive intervention, venous-blood-return to the heart-lung machine and renal function. Patients with hyperlactatemia required longer intensive care and postoperative ventilatory support. Complications were more frequent, especially: renal dysfunction, infections, respiratory and circulatory disorders. Hospital mortality was 13.3% compared to an overall level at 2.2%. The threshold for hyperlactatemia during cardiopulmonary bypass attained 2 mmol/l and predicted increased morbidity and mortality.

Measurement of the activated clotting time during cardiopulmonary bypass: differences between Hemotec ACT and Hemochron Jr apparatus.

Background: Measurement of the activated clotting time (ACT) represents a standard method for coagulatory assessments. The test employs specific agents to trigger the coagulation process. The present study aimed to compare kaolin (Hemotec®) versus a combination of silica, kaolin and phospholipid (Hemochron® Jr) ACTs. Methods: Hemotec® and Hemochron® Jr ACT monitors were compared by simultaneous measurement of paired arterial blood samples (n-114) with respect to precision and bias during clinical conditions of cardio-pulmonary bypass (CPB). The influence of haemodilution on the ACT was tested in an ex-vivo model. Results: The precision of Hemotec® and Hemochron®Jr ACT measurements attained 21±2.6 s versus 27.0±2.6 s(p= 0.126) during CPB and 2.5±2.2 s versus 9.4±6.9 s (p= 0.000) after protamine administration, respectively. The Hemochron® Jr monitor was associated with a bias of −102±13.7 s compared to the Hemotec® ACT monitor (p= 0.000) during CPB and −6.9±2.9 s after protamine (p= 0.025). Linear regression analysis of ACT readings between monitors reached r- 0.526 (p= 0.000). Hemochron® Jr ACT values correlated with the erythrocyte volume fraction r- 0.379 (p= 0.000). Ex-vivo data indicated that the Hemotec® ACT monitor was associated with relatively higher ACT readings after haemodilution. Conclusion: The ACT is not a standardized measure. Test results are strongly associated with the specific compounds used to initiate the coagulation process.

Reversal of heparin after cardiac surgery: protamine titration using a statistical model.

OBJECTIVE To establish a statistical model for determination of protamine dose in conjunction with cardiopulmonary bypass. DESIGN Prospective. SETTING University hospital. PARTICIPANTS Ninety consecutive cardiac surgical patients. INTERVENTIONS None. MEASUREMENTS AND MAIN RESULTS A series of clinically oriented variables were introduced into a statistical model for projection of the protamine dose after cardiopulmonary bypass. The following significant predictors were identified using multivariable regression analysis: The patients body surface area, the administered dose of heparin, heparin clearance, and the preoperative platelet count. The statistical model projected the protamine dose within 3±23 mg of the point-of-care test used as reference. CONCLUSION Protamine dosing based on statistical modeling represents an alternative to point-of-care tests.