Molecular weight of hydroxyethyl starch molecules influences coagulation profile measured by thrombelastography.

BACKGROUND: The consensus about the ideal intravenous fluid in trauma patients remains open. However, hypertonic saline and hydroxyethyl starch (HES) seems to have advantages in terms of immuno-modulatory and haemodynamic effects. Nevertheless clotting abnormalities are frequently reported in association with the use of HES. We investigated the influence of light, medium and heavy molecular weight (MW) hydroxyethyl starch (HES) on coagulation in 29 healthy subjects. METHODS: Ringer's lactate (RL) served as a control solution. Thrombelastography using Haemoscope's Thrombelastograph (TEG) hemostasis system was used to assess the effect of HES polymers and RL. TEG analysis was performed using recalcified native whole blood both with and without the addition of platelet activating factor IV (PAF IV) before and immediately after infusion of one of the solutions. RESULTS: Infusion of RL or one of the three HES solutions exerts an anticoagulant effect as demonstrated by a increase in clot formation time (R) and a decrease in maximum amplitude (MA), and the angle. The addition of PAF IV reversed these changes. CONCLUSIONS: This data indicate clear evidence of platelet activity per se or platelet interaction with the plasmatic coagulation system.

Peri-operative decreased cAMP levels in long-term alcoholic patients.

Long-term alcoholic patients have a five-fold higher risk of post-operative bleeding complications compared with nonalcoholic individuals. Serotonin increases and cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) decrease platelet aggregation. We examined the platelet-rich plasma levels of these substances and agonist-induced platelet aggregation in long-term alcoholic patients before and after surgery. Thirty-three consecutive patients (13 long-term alcoholics and 20 non-alcoholics) scheduled for tumour resections of the upper digestive tract were included in the study. The levels of cAMP were significantly decreased before and after surgery in long-term alcoholic patients, but there were no significant differences in cGMP and serotonin levels in alcoholic compared with non-alcoholic patients. In contrast to previous studies, no significantly altered aggregation responses in long-term alcoholics were found. A possible explanation is decreased inhibition through diminished cAMP levels; cGMP and serotonin do not seem to influence peri-operative haemostasis.

Platelet disorders in uraemia before and after haemodialysis under the influence of low dose aspirin.

Thrombocyte dysfunction and increased bleeding time (BT) are well documented in uraemic patients. However, these patients are frequently medicated with low dose aspirin (ASA) in order to maintain shunt patency and prevent cardiovascular events. Recently, life- threatening gastrointestinal haemorrhage in an uraemic subject taking low dose aspirin has been reported. In this work ASA related bleeding risk in uraemic patients and the effect of haemodialysis on their bleeding tendency was studied by measuring in vitro bleeding time (BT) using the Thrombostat 4000 in 34 uraemic patients on chronic haemodialysis compared to 50 healthy subjects. Our results indicate that low dose aspirin does not influence uraemic thrombopathia 8 to 10h after ingestion but seems to increase bleeding risk shortly after ingestion. Moreover, haemodialysis alters uraemic in vitro BT with regard to the time after ingestion of ASA.

Hydrocortisone improved haemodynamics and fluid requirement in surviving but not non-surviving of severely burned patients.

Recent studies have shown that administration of hydrocortisone may lead to a reduction of catecholamines and to an improved outcome in septic patients. However, there are no data on the use of hydrocortisone in burn patients although in these patients reduction of vasopressors might be even more crucial for outcome due to improvement of skin perfusion. This study presents the first results on the impact of hydrocortisone administration in norepinephrine dependent severely burned patients. In a prospective cohort study fourteen consecutive severely burned patients received, 12h after norepinephrine dependency, a hydrocortisone bolus of 100mg followed by 0.18mg/(kgh) hydrocortisone. The course of the necessary norepinephrine dose, as well as the fluid balance was documented 12h prior and after the first dosage of hydrocortisone. Statistical analysis showed an unexpected increase of the required norepinephrine dosage. A statistical post hoc evaluation of surviving and non-surviving patients revealed a significant increase of norepinephrine in non-survivors whereas in survivors it was possible to reduce norepinephrine significantly. Furthermore, the median fluid requirement of surviving patients could be significantly reduced whereas in the group of non-survivors there was no change of volume needed. Our data suggests that hydrocortisone might be useful in selected patients with severe burn injuries. However, patients not responding to hydrocortisone administrations seem to have a poor prognosis. Our findings are in contrast to previously published data on septic patients, in whom hydrocortisone administration resulted in a reduction of norepinephrine. In burned patients the severity of trauma seems to have more profound influence on the pathophysiological mechanism of sepsis. Due to the high number of non-responders, the potential immune suppression and impaired wound healing caused by the side effects of hydrocortisone, further selection criteria seem to be necessary. A short ACTH-test might be considered prior to hydrocortisone administration to select patients who might benefit from this therapy. In summary, further prospective controlled studies will be necessary to establish hydrocortisone in the routine therapy of severely burned patients.

Effect of non-selective, non-steroidal anti-inflammatory drugs and cyclo-oxygenase-2 selective inhibitors on the PFA-100 closure time.

The place of cyclo-oxygenase (COX)-2 selective non-steroidal anti-inflammatory drugs (NSAIDs) in the peri-operative period remains under discussion. Due to the absence of COX-2 in platelets, the risk of bleeding in patients who use selective NSAIDs is thought to be decreased. We studied the influence of aspirin, diclofenac, lornoxicam and rofecoxib on the in vitro bleeding time using the platelet function analyser (PFA-100). The PFA-100 simulates the process of platelet adhesion and aggregation after vascular injury in vitro. Measurements in 43 volunteers were performed at three time points: before, 3 h, and 12 h after oral ingestion of one of the randomly assigned study medications. Aspirin, diclofenac and lornoxicam had a significant effect on the in vitro closure time, while rofecoxib did not show this effect. This supports the use of COX-2 selective drugs in the peri-operative period to minimise the risk of bleeding.

The role of oxytocin in relation to female sexual arousal.

Oxytocin is clearly involved in human reproduction and serves an important role in sexual arousal. Oxytocin serum levels were measured before and after sexual stimulation in 12 healthy women. Values of oxytocin 1 min after orgasm were significantly higher (p < 0.05) than baseline levels. This finding supports the hypothesis that oxytocin plays a major part in human sexual response both in neuroendocrine function and postcoital behavior.

Validity of acoustic quantification colour kinesis for detection of left ventricular regional wall motion abnormalities: a transoesophageal echocardiographic study.

Transoesophageal echocardiography is a sensitive monitor for intraoperative myocardial ischaemia. Colour kinesis is a new technology for echocardiographic assessment of regional wall motion based on acoustic quantification. We have examined the feasibility and accuracy of quantitative segmental analysis of colour kinesis images to provide objective evaluation of systolic regional wall motion during the perioperative period using transoesophageal echocardiography (TOE). Two-dimensional echocardiograms were obtained in the transgastric short-axis and long-axis views in 60 patients with coronary artery disease undergoing noncardiac surgery. End-systolic colour overlays superimposed on the grey scale images were obtained with colour kinesis to colour encode left ventricular endocardial motion throughout systole. These colour-encoded images were divided into segments and compared with corresponding conventional two-dimensional images. Six hundred of a potential 720 left ventricular wall segments were of sufficient resolution for grading by experts; they diagnosed wall motion abnormalities in 61 of these segments by a conventional method. In comparing the conventional TOE method with colour kinesis, there were 60 true positives, 482 true negatives, 57 false positives and 1 false negative result. This yielded a sensitivity of 98%, specificity of 89%, positive predictive value of 51% and negative predictive value of 100%. Translational and rotational movement of the heart and papillary muscle interference were common problems accounting for false positive diagnoses. We conclude that colour kinesis provides a basis for objective and on-line evaluation of left ventricular regional wall motion which is a sensitive but non-specific method. It may be a useful aid for the less experienced because it can potentially direct the anaesthetist's attention towards specific segments.

Effects of temperature on partial thromboplastin time in heparinized plasma in vitro.

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 degrees C, 35 degrees C, 37 degrees C, 39 degrees C and 41 degrees C in normal human plasma in response to unfractionated heparin. RESULTS: Hypothermia

The effect of hydroxyethyl starch on platelet aggregation in vitro.

UNLABELLED: The effect of hydroxyethyl starch (HES) on hemostasis seems to be minimal when it is used in recommended amounts. A number of studies have investigated the effect of HES on platelet function when administered in vivo, but there has been no study investigating the effect on the isolated platelet function when administered in vitro. A photometrical method to assess platelet function in platelet-rich plasma (approximately 250 x 10(9) platelets/L) was used with platelet aggregation induced using either collagen, epinephrine, adenosine diphosphate, or ristocetin. We found a dose-dependent decrease of platelet aggregation in vitro with either collagen or epinephrine, but not with adenosine diphosphate or ristocetin. However, the changes of HES on platelet aggregation were detected only in doses larger than those routinely used in the clinical setting. Therefore, we conclude that the influence of HES at the recommended doses on initial platelet aggregation may not be clinically relevant. IMPLICATIONS: The effect of hydroxyethyl starch on platelet function and coagulation is discussed. This study showed no influence on platelets in clinically relevant doses in an in vitro model.

Endogenous heparin-like substances significantly impair coagulation in patients undergoing orthotopic liver transplantation.

UNLABELLED: Orthotopic liver transplantation (OLT) is associated with severe bleeding, especially after reperfusion of the grafted liver. Heparin released from the liver graft contributes to postreperfusion coagulopathy. Although patients with liver cirrhosis have increased levels of endogenous heparinoids, the role of these substances during liver transplantation is unclear. Therefore, we performed native and heparinase-modified thrombelastography (TEG) in 72 patients undergoing OLT. TEG was performed at skin incision, 10 min before and 10 min after clamping of the vena cava, 10 min before and 10 min after graft perfusion, and at the end of surgery. Heparinase-modified TEG compared with native TEG demonstrated heparin activity. In contrast to other investigations, we found significant heparin effects before reperfusion, although patients received no exogenous heparin. These heparin effects were greater in patients with cirrhosis compared with patients with cancer as the underlying disease leading to OLT. Administration of coagulation factors is the usual treatment of coagulopathies during OLT. The comparison of native versus heparinase-modified TEG can distinguish between heparin activity or coagulation factor deficiency as a cause of bleeding complications and provides a rational approach to the treatment of bleeding during OLT. IMPLICATIONS: Impaired coagulation function, contributed to by heparin or heparin-like substances, is frequently observed after reperfusion of a transplanted liver. This study demonstrates that a heparinase-modified thrombelastography can identify significant heparin effects in the absence of exogenous heparin administration in patients undergoing liver transplantation.