[Modern anaesthesiological techniques and anticoagulation]. / Moderne Anästhesieverfahren unter Antikoagulation.

The variety of possibilities for medicamentous anticoagulation is constantly growing. Anesthesiologists and pain therapists are confronted with patients being treated with highly effective anticoagulatory or new antiaggregatory substances due to coronary heart disease, stroke or peripheral arterial disease. Especially these patients benefit from neuraxial blockades when undergoing cardiac surgery, revascularization surgery or amputations. The anaesthesiologist needs an overview concerning pharmacology, indications and side-effects of the anti- and procoagulatory substances and has to integrate this knowledge in the treatment concept to prevent haemorrhagic complications. This review depicts basics of coagulation, sites of action of currently applied anticoagulants and Austrian standards for performing modern central and peripheral nerve blocks under anticoagulatory medication. In general anaesthesia, too, the preoperative evaluation of preexisting anticoagulatory therapy is of high significance concerning the derivation of procedures for perioperative coagulation management. To prevent haemorrhagic complications in patients treated with anticoagulatory agents, recommendations concerning the following questions are given: time intervals between the application of anticoagulatory substances and punction, removal of catheters or general anaesthesia and operation; the choice and performance of the locoregional anaesthesiologic method and intraoperative coagulation analysis method; reversion of anticoagulation in acute situations.

The effect of graded hypothermia (36 degrees C-32 degrees C) on hemostasis in anesthetized patients without surgical trauma.

UNLABELLED: The isolated effects of hypothermia on hemostasis have not been investigated in healthy humans. We cooled 16 anesthetized patients scheduled for elective intracranial surgery to 32 degrees C body core temperature and assessed prothrombin time (PT), activated partial thromboplastin time, thrombelastogram (TEG), closure time, and platelet count at 36 degrees C, 34 degrees C, and 32 degrees C body core temperature after the induction of anesthesia but before surgical intervention. Activated partial thromboplastin time, hematocrit, and closure time did not change, whereas PT and platelet count decreased during cooling. Platelet count decreased without a decrease in hematocrit; hence, a dilution by administered fluids seemed unlikely. The small decrease of platelet count is probably clinically irrelevant in patients with normal platelet count and function. The small decrease in PT indicates an alteration of the extrinsic pathway of coagulation. TEG measurements showed a delay of clot formation in temperature-adjusted measurements but showed no change if the test temperature was 37 degrees C. This indicates that hypothermia reduces plasmatic coagulation and platelet reactivity. However, the clot strength is not altered by hypothermia. All coagulation variables remained within the normal ranges. Our results may indicate that moderate short-term (4-h) hypothermia has only minor adverse effects in healthy humans. We can make no statement about the effects of hypothermia of longer duration. IMPLICATIONS: This study investigated the isolated effects of hypothermia in healthy anesthetized humans. We found only minor effects of body temperature reduction to 32 degrees C on assessed coagulation variables, indicating only minor effects in otherwise healthy humans.

Continuous beta-lactam antibiotic therapy in a double-lung transplanted patient with a multidrug-resistant Pseudomonas aeruginosa infection.

BACKGROUND: It is well known that the bactericidal effect of beta-lactam antibiotics is closely related to the time which the serum concentration of the antibiotic remains above the minimal inhibitory concentration of the target pathogen. Thus, the optimal administration of beta-lactam antibiotics would be the continuous infusion of the drug. METHODS: We present a case report with a critically ill double-lung transplanted patient with pneumonia due to a multidrug-resistant Pseudomonas aeruginosa who received continuously 8 g meropenem/24 hr. Based on a previous pharmacokinetic study showing that continuous infusion of meropenem is at least equivalent to intermittent administration this case report is reported to demonstrate the clinical efficacy of continuous infusion. RESULTS: C-reactive protein and pneumonia decreased rapidly when clinical conditions were improved significantly. Continuous administration of meropenem did not interfere with cyclosporine, no side effects were seen, and the patient's renal function was not impaired during the whole period of treatment. CONCLUSION: The continuous administration of beta-lactam antibiotics is a powerful application in critically ill patients to intensify antimicrobial therapy.

Use of abciximab-modified thrombelastography in patients undergoing cardiac surgery.

UNLABELLED: Thrombelastography (TEG) is a reliable coagulation monitoring system that can guide blood product transfusion in cardiac surgery. The maximum amplitude (MA) of TEG measures clot strength, which is dependent on both fibrinogen level and platelet function. Inhibition of platelet function with abciximab-fab is suggested to permit quantitative assessment of the contribution of fibrinogen to clot strength. We hypothesized that abciximab-modified TEG permits prediction of plasma fibrinogen levels and that the difference of standard MA and abciximab-modified MA (deltaMA) is a correlate for platelet function. We correlated abciximab-modified MA with plasma fibrinogen levels and deltaMA with platelet count in patients undergoing coronary revascularization. Correlation between plasma fibrinogen levels and abciximab-modified MA was significant (adjusted r2: 0.8; P < 0.0001). Correlation of deltaMA with platelet count was not significant when calculated in millimeters (adjusted r2: 0.04; P = 0.73). However, when deltaMA was calculated in dynes per square centimeter (deltaGMA), it correlated significantly with platelet count (adjusted r2: 0.51; P < 0.0001). We conclude that abciximab-modified TEG may therefore help to discriminate between hypofibrinogenemia and platelet dysfunction as a cause of decreased MA. IMPLICATIONS: We examined the use of abciximab-modified thrombelastography in patients undergoing cardiac surgery. Modification of thrombelastography with abciximab-fab allows prediction of fibrinogen levels, despite coagulation altered by cardiac surgery. The difference of standard maximum amplitude and abciximab-modified maximum amplitude correlates with platelet function when expressed in dynes per square centimeter.

Effects of hypothermia on thrombelastography in patients undergoing cardiopulmonary bypass.

Thrombelastography (TEG) correlates with postoperative chest drain output in patients undergoing cardiopulmonary bypass (CPB). In vitro incubation with heparinase allows TEG monitoring during CPB, despite heparin anticoagulation. Hypothermia impairs coagulation, but these effects cannot be assessed by standard coagulation tests performed at 37 degrees C. The aim of this study was to assess the effects of hypothermia on TEG. Therefore, we have compared normothermic and temperature-adapted TEG in 30 patients undergoing CPB. Our data showed significantly impaired reaction time (r), kinetic time (k), and angle alpha (alpha) in temperature-adapted compared with normothermic TEG. Maximum amplitude (MA), reflecting absolute clot strength, was not affected at temperatures of 33-37 degrees C. These findings indicate a decrease in the speed of clot formation, but not absolute deterioration in clot quality. Furthermore, heparinase-modified TEG indicated that there were nine cases in which heparin effects persisted after heparin reversal with protamine, providing a rational guide to protamine therapy.

High-dose recombinant human erythropoietin stimulates reticulocyte production in patients with multiple organ dysfunction syndrome.

OBJECTIVE: To investigate erythropoietin (EPO) production and the erythropoietic potency of recombinant human EPO in the multiple organ dysfunction syndrome. DESIGN: Randomized, prospective, controlled clinical trial. MATERIALS AND METHODS: Patients received either 600 IU/kg intravenous EPO three times weekly (n = 9) or saline (control, n = 10). MEASUREMENTS: EPO levels, circulating soluble receptors for tumor necrosis factor and interleukin-2, levels of interleukin-6 and intercellular adhesion molecule, and early peripheral blood cell progenitors. RESULTS: EPO production in the control group remained low. Pharmacologic EPO blood levels were associated with increased reticulocyte counts compared with both controls (p < 0.04) and baseline (p < 0.006). Increased levels of soluble receptors for tumor necrosis factor in the treatment group compared with the controls did not prevent this effect. Interleukin 6 inhibited reticulocyte production. CONCLUSION: Despite increased cytokine levels, pharmacologic EPO blood levels were associated with increased reticulocyte counts in patients with multiple organ dysfunction syndrome.

Mild hypothermia increases blood loss and transfusion requirements during total hip arthroplasty.

BACKGROUND: In-vitro studies indicate that platelet function and the coagulation cascade are impaired by hypothermia. However, the extent to which perioperative hypothermia influences bleeding during surgery remains unknown. Accordingly, we tested the hypothesis that mild hypothermia increases blood loss and allogeneic transfusion requirements during hip arthroplasty. METHODS: Blood loss and transfusion requirements were evaluated in 60 patients undergoing primary, unilateral total hip arthroplasties who were randomly assigned to normothermia (final intraoperative core temperature 36.6 [0.4] degrees C) or mild hypothermia (35.0 [0.5] degrees C). Crystalloid, colloid, scavenged red cells, and allogeneic blood were administered by strict protocol. FINDINGS: Intra- and postoperative blood loss was significantly greater in the hypothermic patients: 2.2 (0.5) L vs 1.7 (0.3) L, p < 0.001). Eight units of allogeneic packed red cells were required in seven of the 30 hypothermic patients, whereas only one normothermic patient required a unit of allogeneic blood (p < 0.05 for administered volume). A typical decrease in core temperature in patients undergoing hip arthroplasty will thus augment blood loss by approximately 500 mL. INTERPRETATION: The maintenance of intraoperative normothermia reduces blood loss and allogeneic blood requirements in patients undergoing total hip arthroplasty.