Jonathan L. Parmet

BACKGROUND: Prophylactic administration of the antifibrinolytic drug tranexamic acid decreases bleeding and transfusions after cardiac operations. However, the best dose of tranexamic acid for this purpose remains unknown. This study explored the dose-response relationship of tranexamic acid for hemostatic efficacy after cardiac operation. METHODS: In prospective, randomized, double-blinded fashion, 148 patients undergoing cardiac operation with extracorporeal circulation were divided into six groups: a placebo group and five groups receiving tranexamic acid in loading doses before incision (range 2.5 to 40 mg.kg-1) and one-tenth the loading dose hourly for 12 h. The mass of blood collected by chest tubes over 12 h represented blood loss. Allogeneic transfusions within 12 h and within 5 d of surgery were tallied. RESULTS: The six groups presented similar demographics. Patients receiving placebo had increased postoperative D-dimer concentration compared to groups receiving tranexamic acid. Patients receiving at least 10 mg.kg-1 tranexamic acid followed by 1 mg.kg-1.h-1 bled significantly less (365, 344, and 369 g.12 h-1, respectively, for those three groups) compared with patients who received placebo (552 g, P < 0.05). Tranexamic dose did not affect transfusions. Only initial hematocrit affected whether a patient received an allogeneic transfusion within 5 days of operation (odds ratio 2.08 for each 3% absolute decrease in hematocrit). CONCLUSIONS: Prophylactic tranexamic acid, 10 mg.kg-1 followed by 1 mg.kg-1.h-1, decreases bleeding after extracorporeal circulation. Larger doses do not provide additional hemostatic benefit.

BACKGROUND: Desmopressin-induced release of tissue plasminogen activator from endothelial cells may explain the absence of its hemostatic effect in patients undergoing cardiac surgery. Prior administration of the antifibrinolytic drug tranexamic acid might unmask such an effect, and combination therapy might thereby improve postoperative hemostasis. METHODS AND RESULTS: A double-blinded design randomly allocated 163 adult patients undergoing coronary revascularization, valve replacement, both procedures, or repair of atrial septal defect to four treatment groups: placebo, tranexamic acid given as 10 mg/kg over 30 minutes followed by 1 mg.kg-1.hr-1 for 12 hours initiated before skin incision, desmopressin given as 0.3 micrograms/kg over 20 minutes after protamine infusion, and both drugs. One surgeon performed all operations. Blood loss consisted of mediastinal tube drainage over 12 hours. Follow-up visits sought evidence of myocardial infarction and stroke. Desmopressin decreased neither the 12-hour blood loss nor the amount of homologous red cells transfused. Tranexamic acid alone significantly reduced 12-hour blood loss, by 30% (mean, 318 versus 453 ml; p less than 0.0001), without enhancement by desmopressin. Tranexamic acid also decreased the proportion of patients receiving homologous blood within 12 hours of operation (8% versus 21%, p = 0.024) and within 5 days of operation (22% versus 41%, p = 0.011). CONCLUSIONS: Desmopressin exerts no hemostatic effect, with or without prior administration of antifibrinolytic drug. Prophylactic tranexamic acid alone appears economical and safe in decreasing blood loss and transfusion requirement after cardiac surgery.

UNLABELLED: In 1995, our department of anesthesiology established an airway team to assist in treating unanticipated difficult endotracheal intubations and an airway quality improvement (QI) form to document the use of emergency airway techniques in airway crises (laryngeal mask airway [LMA], flexible fiberoptic bronchoscopy, retrograde intubation [RI], transtracheal jet ventilation [TTJV], and cricothyrotomy). Over a 2-yr period, team members and staff anesthesiologists completed airway QI forms to document the smallest peripheral SpO2 during an airway crisis, the number of direct laryngoscopies (DL) performed before using an emergency airway technique, and the emergency airway technique that succeeded in rescue ventilation. Team members agreed to use the LMA as the first emergency airway technique to treat the difficult ventilation/difficult intubation scenario. A SpO2 value < or =90% during mask ventilation defined difficult ventilation. Inability to perform tracheal intubation by DL defined difficult intubation. An increase in the SpO2 value >90% defined rescue ventilation. Review of airway QI forms from October 1, 1995 until October 1, 1997 revealed 25 cases of difficult ventilation/difficult intubation. Before airway rescue, the median SpO2 was 80% (range 50%-90%), and there were four median attempts at DL (range one to nine). The LMA had a success rate of 94% (95% confidence interval [CI] 77-100). Flexible fiberoptic bronchoscopy, TTJV, RI, and surgical cricothyrotomy had success rates of 50% (95% CI 0-100), 33% (95% CI 0-100), 100% (95% CI 37-100), and 100% (95% CI 37-100), respectively. LMA insertion as the first alternative airway technique was useful in dealing with unanticipated instances of simultaneous difficulty with mask ventilation and tracheal intubation. IMPLICATIONS: Twenty-five cases of simultaneous difficulty with mask ventilation and tracheal intubation occurred after the induction of general anesthesia during the study period. The laryngeal mask was used in 17 cases, and it provided rescue ventilation without complication in 94% of these cases (95% confidence interval 77-100).

In 1995, our department of anesthesiology established an airway team to assist in treating unanticipated difficult endotracheal intubations and an airway quality im-provement (QI) form to document the use of emergency airway techniques in airway crises (laryngeal mask airway [LMA], flexible fiberoptic bronchoscopy, retrograde intubation [RI], transtracheal jet ventilation [TTJV], and cricothyrotomy). Over a 2-yr period, team members and staff anesthesiologists completed airway QI forms to document the smallest peripheral SpO2 during an airway crisis, the number of direct laryngoscopies (DL) performed before using an emergency airway technique, and the emergency airway technique that succeeded in rescue ventilation. Team members agreed to use the LMA as the first emergency airway technique to treat the difficult ventilation/difficult intubation scenario. A SpO2 value <or=to90% during mask ventilation defined difficult ventilation. Inability to perform tracheal intubation by DL defined difficult intubation. An increase in the SpO2 value >90% defined rescue ventilation. Review of airway QI forms from October 1, 1995 until October 1, 1997 revealed 25 cases of difficult ventilation/difficult intubation. Before airway rescue, the median SpO2 was 80% (range 50%-90%), and there were four median attempts at DL (range one to nine). The LMA had a success rate of 94% (95% confidence interval [CI] 77-100). Flexible fiberoptic bronchoscopy, TTJV, RI, and surgical cricothyrotomy had success rates of 50% (95% CI 0-100), 33% (95% CI 0-100), 100% (95% CI 37-100), and 100% (95% CI 37-100), respectively. LMA insertion as the first alternative airway technique was useful in dealing with unanticipated instances of simultaneous difficulty with mask ventilation and tracheal intubation. Implications: Twenty-five cases of simultaneous difficulty with mask ventilation and tracheal intubation occurred after the induction of general anesthesia during the study period. The laryngeal mask was used in 17 cases, and it provided rescue ventilation without complication in 94% of these cases (95% confidence interval 77-100). (Anesth Analg 1998;87:661-5)

The right atrium and the right ventricle of fifty-five patients were imaged with transesophageal echocardiography during fifty-nine total knee arthroplasties performed with cement and the use of general anesthesia. The patients ranged in age from thirty-two to eighty-three years (mean, 65.5 years). Cardiopulmonary parameters were measured with use of hemodynamic monitoring systems, such as pulse oximeters, pulmonary artery catheters, and radial artery catheters. In addition, a femoral vein catheter was inserted on the side of the operation in ten of the fifty-five patients. Showers of echogenic material traversing the right atrium, the right ventricle, and the pulmonary artery after the tourniquet was deflated were observed to various degrees in all patients and lasted three to fifteen minutes. The mean peak intensity occurred within thirty seconds (range, twenty-four to forty-five seconds) after the tourniquet was released. The mean mixed venous oxygen saturation (and standard error of the mean) decreased (from 83+/-0.9 to 72+/-1.5 per cent) and the mean pulmonary arterial pressure increased (from 20+/-1.0 to 27+/-1.0 millimeters of mercury [2.67+/-0.13 to 3.60+/-0.13 kilopascals]), compared with the values before the tourniquet was released, in all patients. The pulmonary vascular resistance index increased after release of the tourniquet (to a maximum of 328+/-29 dyne.s.cm(-5).m2; p = 0.00002) only in the patients who had echogenic material that was at least 0.5 centimeter in diameter. Clinical pulmonary embolism developed postoperatively in three patients; all three had had echogenic particles that were more than 0.5 centimeter in maximum diameter on imaging. Blood aspirated from one of the pulmonary artery catheters and from five of the ten femoral vein catheters demonstrated fresh venous thrombus. Histological evaluation of the aspirates failed to demonstrate fat, marrow, or particles of polymethylmethacrylate. Surgeons should consider acute pulmonary embolism as a diagnosis when evaluating a patient who has hemodynamic collapse during total knee arthroplasty performed with cement.