Roger A. Vertrees

Adverse effects of postoperative infusion of shed mediastinal blood

BACKGROUND Postoperative infusion of shed mediastinal blood has been used in an effort to decrease blood usage after cardiac operations. Recent experience has suggested that this practice may actually lead to a delayed increase in bleeding. METHODS In a prospective, randomized study, 40 patients undergoing coronary artery bypass grafting with shed mediastinal blood collected in a cardiotomy reservoir were divided into two equal groups and studied during their first 4 hours in the intensive care unit. Shed mediastinal blood was directly infused in group I (n = 20), whereas in group II (n = 20), it was not. In group II, if a sufficient volume of red cells was present to allow processing (n = 5), washed red cells were infused. Variables studied before and after infusion were the amount of blood lost and infused, homologous blood transfused, complete blood count and differential, serum fibrinogen, fibrin split products, D-dimers, clotting factors, prothrombin time, activated partial thromboplastin time, thromboelastograms, plasma-free hemoglobin, complement factors C3 and C4, creatine kinase and its MB isoenzyme, and body temperature. RESULTS After infusion of shed mediastinal blood, elevated levels of fibrin split products and D-dimers were found in significantly more patients in group I. The thromboelastogram index was normal in 76% of patients in group II but in only 12.5% in group I. Group I also had an increase in band neutrophils, a greater number of febrile patients, higher serum levels of creatine kinase, its MB isoenzyme, and plasma-free hemoglobin, and greater blood loss during hours 3, 4, and 5 in the intensive care unit. The volume of red cells in shed mediastinal blood (hematocrit, 9% to 10%) was small, resulting in clinically insignificant autotransfusion when infused directly, and insufficient for cell processing in most patients. CONCLUSIONS These data support those in previous studies that direct infusion of shed mediastinal blood does not save substantial amounts of autologous red cells and can cause a delayed coagulopathy and other adverse effects that may be harmful to patients postoperatively.

Mixed Venous Oxygen Saturation During Cardiopulmonary Bypass Poorly Predicts Regional Venous Saturation

Mixed venous oxygen saturation is generally accepted as an indicator of adequacy of systemic oxygen delivery; however, cardiopulmonary bypass (CPB) may alter this relationship.Major postoperative complications potentially secondary to inadequate oxygen delivery during CPB indicate that mixed venous oxygen saturation may not detect regional venous desaturation during CPB. We therefore tested the hypothesis that mixed venous oxygen saturation and pH did not predict regional venous oxygen saturations and pH during 2 h of bypass in a swine model. Six immature swine (27-34 kg) received standard normothermic CPB. Sagittal sinus and portal vein oxygen saturations and blood gases were measured at 30, 60, 90, and 120 min of bypass. Although the venous reservoir oxygen saturation remained unchanged during 2 h of bypass, sagittal sinus saturation and pH decreased significantly (66% +/- 3.3% to 33% +/- 2.2% and 7.38 +/- 0.04 to 7.23 +/- 0.05, respectively). Likewise in the portal vein, oxygen saturation and pH also decreased (82% +/- 2.4% to 59.3% +/- 3.9% and 7.39 +/- 0.03 to 7.27 +/- 0.06, respectively). We conclude that profound regional venous desaturation and progressive regional acidemia may go undetected even when a standard pump flow rate of 100 mL centered dot kg-1 centered dot min-1 is used and mixed venous oxygen saturation is normal. (Anesth Analg 1995;80:466-72)

Whole-body hyperthermia: a review of theory, design and application

The intentional induction of elevated body temperature to treat malignant lesions has its origins in the 18th century. The mechanism of heat-induced cell death is not clear; however, heat induces a variety of cellular changes. For heat to exert a therapeutic effect, pathogens (bacteria, viruses, or neoplastic tissues) need to be susceptible within temperature ranges that do not exert deleterious effects on normal tissues. Hyperthermia has been used successfully to treat isolated neoplastic lesions of the head and neck, regional tumors such as melanoma of the limb, and is under investigation as either an adjunct to, or therapy for, locally disseminated and systemic diseases. The clinical utility of perfusion hyperthermia has evolved into three approaches -isolated organ or limb, tumorous invasion of a cavity, and systemic or metastatic spread. When whole-body hyperthermic treatment has been tried, it has been induced in the patient by submersion in hot wax or liquid, wrapping in plastic, encasement in a high-flow water perfusion suit, or by extracorporeal perfusion. Our group has developed an extracorporeal method, veno-venous perfusion-induced systemic hyperthermia, that was used first to safely heat swine homogenously to an average body temperature of 43°C for 2 h. More recently, a Phase I clinical trial has been completed in which all patients were safely heated to 42 or 42.5°C for 2 h and survived the 30-day study period. We have been sufficiently encouraged by these results and are continuing to develop this technology.

Technique of controlled reperfusion of the transplanted lung in humans

BACKGROUND Reperfusion injury remains a significant and sometimes fatal problem in clinical lung transplantation. Controlled reperfusion of the transplanted lung using white cell-filtered, nutrient-enriched blood has been shown recently to significantly ameliorate reperfusion damage in a porcine model. We modified this experimental technique and applied it to human lung transplantation. METHODS Approximately 1,500 mL of arterial blood was slowly collected in a cardiotomy reservoir during the lung implant, and mixed to make a 4:1 solution of blood:modified Buckberg perfusate. This solution was passed through a leukocyte filter and into the transplant pulmonary artery for 10 minutes, at a controlled rate (200 mL/min) and pressure (less than 20 mm Hg), immediately before removal of the vascular clamp. RESULTS Five patients underwent lung transplantation (1 bilateral, 4 single lung) using this technique. All patients were ventilated on a 40% fraction of inspired oxygen within a few hours and extubated on or before the first postoperative day. CONCLUSIONS Controlled reperfusion of the transplanted lung with white cell-filtered, nutrient-enriched blood has given excellent functional results in our small initial clinical series.

Synergistic interaction of hyperthermia and gemcitabine in lung cancer

Hyperthermia increases cytotoxicity of various antineoplastic agents. We investigated the cytotoxic effects of Gemcitabine and/or hyperthermia on BZR-T33 (human non-small-cell lung cancer cells) in vitro and in immune-suppressed athymic nude mice. Isobologram analysis of monolayer cell cultures for cytotoxicity demonstrates a synergistic interaction between hyperthermia and Gemcitabine. Clonogenic results show significant reductions in surviving fractions and colony size for both therapies; greatest reduction was for the combined therapy group. Using cell cycle analysis, hyperthermia enhanced Gemcitabine-induced G2-M arrest resulting in destruction of 3.5 log cells. Apoptotic studies (Annexin-V FITC staining) showed that hyperthermia augmented Gemcitabine-induced apoptosis. Transmission electron microscopy demonstrated pathology observed in cultures exposed to either therapy present in cultures exposed to both therapies. Studies in nude mice show that the combination therapy group had both an initial decrease in tumor size, and a significantly delayed rate of growth. Additionally, using tumor material harvested from nude mice two days after end to treatment reveals a significantly greater apoptotic index and significantly smaller mitotic index for the combined therapy group. Western blots of the same tumor material, showed that heat shock protein 70 was not significantly increased, however, caspase-3 activity of was significantly increased because of the combined therapy. In conclusion, the combined therapy is synergistic in effect because of hyperthermia enhancing Gemcitabine-induced apoptosis.

Oncogenic ras results in increased cell kill due to defective thermoprotection in lung cancer cells

BACKGROUND The survival response of normal cells to heat stress is an upregulation of heat shock proteins and ras protein activation. We hypothesized that in lung cancer cells the presence of oncogenic ras interferes with thermoprotective mechanisms resulting in cell death. METHODS An equal number of lung tissue culture cells (normal and cancerous) were subjected to either heat stress and then recovery (43 degrees C for 180 minutes, 37 degrees C for 180 minutes) or recovery alone (37 degrees C for 360 minutes). End points were surviving number of cells, cell-death time course, heat shock protein (HSP70, HSC70, HSP27) expression before and after heat stress, and time course for HSP70 expression during heat stress and recovery. Heated cells were compared with unheated control cells, then this difference was compared between cell types. RESULTS Heat stress in normal cells caused an 8% decrease in cell number versus a 78% +/- 5% decrease in cancer cells (p < 0.05). In normal cells, heat stress caused a 4.4-fold increase in HSP70, no change in HSC70, and a 1.7-fold increase in HSP27. In contrast, cancer cells initially contained significantly less HSP70 (p < 0.05), and there was a 27-fold increase in HSP70 and a 2-fold increase in HSC70 with no HSP27 detected (comparison significant, p < 0.05). HSP70 time course in normal cells showed that HSP70 increased 100-fold, reaching a vertex at 2 hours and remaining elevated for 24 hours; in cancer cells, HSP70 maximum expression (100-fold) peaked at 5 hours,,then decreased to slightly elevated at 24 hours. CONCLUSIONS Cancer cells with oncogenic ras have defective thermoprotective mechanism(s) causing increased in vitro cell death, which provides an opportunity for thermal treatment of lung cancer.

Hypertonic saline dextran prime reduces increased intracranial pressure during cardiopulmonary bypass in pigs

Children and adults who develop neurologic deficits after cardiac surgery may experience cerebral ischemia during cardiopulmonary bypass. Increased intracranial pressure (ICP) may contribute to cerebral ischemia during bypass. Hypertonic saline dextran (HSD), a hyperosmotic, hyperoncotic resuscitation solution, decreases ICP in trauma resuscitation. We hypothesized that HSD would decrease ICP, reduce brain water, and reduce intravascular fluid requirements during bypass. Twelve swine were divided into two bypass groups: Group 1 (ISO = isotonic) received as prime 1 L of lactated Ringers solution and 500 mL of 6% hydroxyethyl starch. Group 2 (HSD = hypertonic saline/dextran) received as prime 1 L of lactated Ringers solution, 500 mL of 6% hydroxyethyl starch, and 1 mL/kg of 24% hypertonic saline/25% dextran. Normothermic bypass was instituted at 100 mL.kg-1.min-1. ICP increased significantly during bypass with ISO prime but not with HSD. Brain water in the cerebrum did not differ between groups but was reduced in the cerebellum to 75.9% +/- 1.4%. We conclude that HSD prevented any significant increase in ICP during normothermic bypass, and substantially improved fluid balance during bypass. In cardiac surgery patients in whom maintaining decreased ICP and reducing isotonic fluid administration is important, HSD may be a useful addition to the bypass prime solution.

Regulation of lung cancer cell growth and invasiveness by β-TRCP†

Beta‐transducin‐repeat‐containing protein (β‐TRCP) serves as a substrate‐recognition subunit of Skp1/Cullin/F‐box (SCF)β‐TRCP E3 ligases, involved in regulation of several important signaling molecules. SCFβ‐TRCP E3 ligases play a critical role in cell mitosis as well as in various signaling pathways. Here, we provide evidence to support that β‐TRCP negatively regulates cell growth and motility of lung cancer cells. With specific antibodies, we detect loss of β‐TRCP1 protein in several lung cancer cell lines. One cell line contains an inactivated mutation of the β‐TRCP1 gene. Loss of β‐TRCP1 protein is also found in subsets of lung cancer specimens. We observe that retrovirus‐mediated stable expression of β‐TRCP1 in β‐TRCP1 negative cells inhibits cell growth in soft‐agar and tumor formation in nude mice. Furthermore, expression of β‐TRCP1 alters cell motility, as indicated by morphological changes and a reduced level of active matrix metalloproteinase (MMP)11. Conversely, inactivation of β‐TRCP1 by specific siRNA accelerates cell invasion. Of the 10 known substrates of SCFβ‐TRCP E3 ligases, the protein level of cell division cycle 25 (CDC25)A is clearly affected in these lung cancer cells. Cells treated with CDC25A inhibitors become less invasive. Thus, loss of β‐TRCP1 may promote both growth and cell motility of lung cancer cells, possibly through regulation of CDC25A and the MMP11 level.

Heparinless extracorporeal bypass for treatment of hypothermia.

In an attempt to assess the changes occurring to the coagulation profile during internal active core rewarming with partial cardiopulmonary bypass (CPB) without heparin anticoagulation, five pigs were anesthetized, and a model for severe to moderate hypothermia was created. Femoral-femoral bypass with Bio-Pump, heat exchanger, and a membrane oxygenator were used during the rewarming for 64.8 +/- 8.5 minutes. There were no statistically significant changes in platelet count, platelet index, activated clotting time (ACT), partial thromboplastin time (PTT), prothrombin time (PT), fibrinogen, fibrinogen index and fibrin split products (p greater than 0.05). There were no thromboembolic sequelae seen at autopsy. The components of the CPB circuit showed no signs of formation of aggregates or thrombi. The results of this study are attributed to the nonthrombogenic, atraumatic design of the Bio-Pump and the enhanced physiological fibrinolysis seen in the first hour of CPB. We concluded that heparinless CPB may serve as a safe alternative for active core rewarming for severe to moderate hypothermia.

Extracorporeal heparin adsorption following cardiopulmonary bypass with a heparin removal device : An alternative to protamine

OBJECTIVES To evaluate the therapeutic efficacy and applicability of a heparin removal device (HRD) based on plasma separation and poly-L-lysine (PLL) affinity adsorption as an alternative to protamine in reversing systemic heparinization following cardiopulmonary bypass (CPB). DESIGN A prospective study. SETTING University research laboratory. SUBJECTS Adult female swine (n=7). INTERVENTIONS Female Yorkshire swine (n=7, 67.3+/-3.5 [SEM] kg) were subjected to 60 mins of right atrium-to-aortic, hypothermic (28 degrees C) CPB. After weaning from CPB, the right atrium was recannulated with a two-stage, dual-lumen cannula which was connected to an HRD via extracorporeal circulation. Blood flow was drained at 1431.2+/-25.4 mL/min from the inferior vena cava, through the plasma separation chamber of the HRD (where heparin was bound to PLL), and reinfused into the right atrium. The HRD run time was determined by a previously established mathematical model of first-order exponential depletion. MEASUREMENTS AND MAIN RESULTS Heart rate, mean arterial pressure, pulmonary arterial pressure, central venous pressure, kaolin and celite activated clotting time (ACT), activated partial thromboplastin time (APTT), heparin concentration, and plasma free hemoglobin were obtained before, during, and after the use of the HRD. Pre-CPB ACT was 167+/-89 secs (kaolin) and 99+/-7 secs (celite), and APTT was 34+/-5 secs. The HRD run time averaged 27.4 +/-1.5 mins targeted to remove 90% total body heparin. Use of the HRD was not associated with any adverse hemodynamic reactions or increases in plasma free hemoglobin. The heparin concentration immediately following CPB was 4.85+/-0.24 units/mL, with ACT >1000 secs and APTT >150 secs in all animals. During heparin removal, total body heparin content followed first-order exponential depletion kinetics. At the end of the HRD run, heparin concentration decreased to 0.51+/-0.09 units/mL, with kaolin ACT returning to 177+/-22 secs, celite ACT returning to 179+/-17 secs, and APTT returning to 27+/-3 secs (p > .05 vs. pre-CPB baseline for all variables). CONCLUSIONS The HRD is capable of reversal of anticoagulation following CPB without significant blood cell damage or changes in hemodynamics. The HRD, therefore, can serve as an alternative to achieve heparin clearance in clinical situations where use of protamine may be contraindicated.