Summary

Background and objective: Different types of polymer surfaces affect the activation of platelets and coagulation pathway containers depending on their surface qualities. Importantly, this could produce variability of coagulation results obtained with thrombelastographical analysis. We assessed the effects of blood storage on thrombelastograph, TEG®, variables using polypropylene and polycarbonate containers. Methods: An in vitro experiment was performed, with eight volunteers in each limb. Fresh whole blood was stored in polypropylene or polycarbonate tubes prior to TEG® analysis, to assess the role of these plastics in the TEG® results obtained. Results: The polycarbonate tubes displayed slower onset of coagulation and greater variability of data for all four basic TEG variables (r-time, k-time, α-angle and maximum amplitude, P < 0.05). Polycarbonate results fell outside manufacturer reference ranges. Conclusions: It is likely that this is due to the altered surface properties and charge effects of the containers affecting proteins and platelets differently. Caution should be used in choosing which containers are used for storage of fresh blood prior to coagulation assessment, as variable results will follow where different types of plastic containers are employed.

Background and objective Perioperative hypothermia has been found to impair the coagulation cascade and to increase blood loss and transfusion requirements. The effect of concomitant in vitro heparinization on coagulation during hypo- and hyperthermic conditions has not been well defined.

Methods In the present study, activated partial thromboplastin time was examined in vitro at 33°C, 35°C, 37°C, 39°C and 41°C in normal human plasma in response to unfractionated heparin.

Results Hypothermia ≤ 35°C prolonged activated partial thromboplastin time by 10% compared with test temperatures at 37°C (P < 0.05). Hyperthermia alone had no effect. Unfractionated heparin (0.1–0.4 IU mL−1) increased activated partial thromboplastin time in a dose-dependent manner (by 189% at 0.4 IU mL−1, P < 0.05). Test temperatures of 33°C and 41°C increased heparin-induced prolongation of activated partial thromboplastin time. At a heparin concentration of 0.4 IU mL−1, hypothermia (33°C) and hyperthermia (41°C) prolonged partial thromboplastin time by 12% and 22%, respectively, compared with normothermic test temperature of 37°C within the heparin group (P < 0.05).

Conclusions These observations suggest that both hypo- and hyperthermia increase the response to heparin in vitro. Further studies are needed to identify the effect of patient’s body temperature on heparin activity and bleeding tendency in vivo.

Profound and complex coagulation disorders are encountered during liver transplantation. They include preoperative coagulation disorders related to the liver disease and haemostatic changes related to the procedure itself. They commonly lead to increased intraoperative bleeding, especially due to increased fibrinolysis, the contribution of which can be demonstrated by the relative efficacy of antifibri-nolytics. Given the multifactorial nature of bleeding in liver transplantation, preoperative coagulation tests cannot predict blood loss even if some statistical relationship is occasionally found.Preoperative correction of coagulation defects has not been shown to be effective in reducing intraoperative bleeding. Throughout the procedure, a rapid and sensitive method for monitoring coagulation is necessary in order to guide the rational use of blood components and pharmacological agents. The usefulness of such a method to assist management of blood loss or blood component requirements is poorly documented and controversial.

A retrospective survey was undertaken of 142 adults who had undergone cardiac surgery with cardiopulmonary bypass. According to the manufacturer's instructions for thromboelastography, patients were identified as showing evidence of fibrinolysis if after coming off bypass the Ly30 index was ≥7.5%. In the 20 fibrinolytic patients, fibrinolysis was readily corrected by tranexamic acid but these patients needed more colloid and more vasopressor support than the non-fibrinolytic patients. There were three deaths, all in the fibrinolytic patients. It is possible that fibrinolysis is a marker for onset of systemic inflammation syndrome. It is recommended that, until the association between fibrinolysis and worse outcome is investigated further, patients showing fibrinolysis early after cardiopulmonary bypass should not be discharged too soon from intensive care.

The role of routine coagulation studies in the management of patients suffering from epistaxis is unclear. In an attempt to address this issue the case notes of all emergency admissions for epistaxis to a large Scottish teaching hospital were retrospectively reviewed over a one-year period. One hundred and forty patients (63 male, 77 female) were admitted between January and December 1998. The patients who had coagulation studies were identified and their results analysed. A total of 121 patients (86.4 per cent) had coagulation studies performed. Of these, 10 (8.3 per cent) had abnormal results and all were taking warfarin or a combination of warfarin and aspirin. No other coagulation abnormalities were identified. This study supports the view that there does not appear to be a role for routine coagulation studies in patients admitted with epistaxis. The investigation for potential haemostatic disorders should be performed when clinically indicated and, if necessary, in consultation with the haematology service.

Abstract Epistaxis remains the most common ENT emergency. The use of coagulation studies in Scotland to manage these patients was investigated to determine current practice. The study took the form of a postal questionnaire sent to all practising ENT consultants and a telephone survey of ENT senior house officers working in Scotland. Of the 60 questionnaires circulated amongst consultants, 55 responses were received (92 per cent). Thirty-eight consultants (70 per cent) indicated that they did not routinely request a coagulation screen for their patients, however, 30 per cent (16) did. Forty-three of the 45 junior staff were available for interview, 22 (51 per cent) of whom routinely requested coagulation studies. While the majority of consultants did not request routine coagulation studies, there did not appear to be any consensus among the junior staff. Although there is a paucity of scientific information with regard to this aspect of epistaxis patient management, there is support in the literature for targeted rather than blanket testing. There is perhaps a need to address this issue within individual departments, to achieve uniformity of practice, and to improve communication between junior and senior staff.