Lewis I. Gottschalk

Celite-activated thrombelastography in children

STUDY OBJECTIVE To quantify global coagulation and establish normal ranges for the celite-activated thrombelastograph (TEG) in healthy pediatric patients. DESIGN Prospective observational study. SETTING Operating suite of a university-based hospital. PATIENTS 110 healthy pediatric patients in four age groups and 25 healthy adult patients. INTERVENTIONS Blood sampling for the celite-activated TEG was carried out after anesthetic induction. MEASUREMENTS TEG indices: R time (reflecting time to fibrin formation), K time and alpha angle (fibrinogen-platelet interaction), maximum amplitude (reflecting maximal clot strength, platelet and fibrinogen function), TEG index (mathematical incorporation of the prior four measurements), and percent fibrinolysis at 30 minutes, were all recorded. MAIN RESULTS Statistically significant differences between <12-month group in angle (compared to 25-48 month group) and % fibrinolysis (compared to all other pediatric groups). Significant differences in angle between two pediatric groups and adult group, and in the TEG index between three pediatric groups and adult group (all differences p < 0.05). CONCLUSIONS These data identify changes of small magnitude in three celite-TEG parameters in healthy children compared to adults, without implication of abnormal coagulation between groups. Changes do not seem to be consistently related to age and will be useful for clinicians using the TEG to monitor (ab) normal coagulation in pediatric patients.

Sonoclot analysis in healthy children.

Although use of the Sonoclot device (Sienco, Inc., Morrison, CO) has been reported in isolated pediatric cases and in small reports in neonates, there are no published data for normal pediatric patients. As the device is used in situations of abnormal coagulation, such as cardiac and liver transplantation surgery, our aim was to determine normal data ranges in healthy pediatric surgical patients. Blood was withdrawn after anesthetic induction, and the Sonoclot activated clotting time, rate of clot formation, time to peak amplitude, and peak amplitude was compared among four pediatric groups (<12 mo, 13–24 mo, 25–48 mo, 49 mo–9 yr) and an adult group. The Sonoclot activated clotting time in the <12-mo and the Adult groups were shorter than the oldest group of children (P < 0.05), although all were within the anticipated normal range, and there were no significant differences in clot rate, peak amplitude, and time to peak amplitude among groups without apparent trends with increasing age. These Sonoclot variables quantify adequate global clot formation in pediatric patients and will facilitate clinical coagulation management with appropriate pediatric normal ranges, avoiding the application of extrapolated adult data to children.

Clopidogrel and platelet transfusion in patients undergoing coronary artery bypass graft surgery.

in a supplement in Anesthesia and Analgesia 2000; 90: SCA 14. Anaesthesia, 2003, 58, pages 597–616 Correspondence ..................................................................................................................................................................................................................... 2003 Blackwell Publishing Ltd 603 segment elevation myocardial infarction. Circulation 2002; 106: 1893–900. 2 Kovesi T, Royston D. Is there a problem with platelet active drugs? British Journal of Anaesthesia 2002; 29: 159–63. Monitoring of platelet function We read with interest the recent review about thienopyridine antiplatelet drugs (Kam & Nethery. Anaesthesia 2003; 58: 28–35). A major problem faced by anaesthetists is the monitoring of the effects of antiplatelet medication. Although the platelet function analyser (PFA-100, Dade Behring, Dearfield, IL) appears to be the answer to this problem, it is a global test of primary haemostasis and is not specific for antiplatelet drugs [1]. The PFA-100 has been used to monitor the antiplatelet effect of aspirin [2]; however, the results may be affected by the citrate concentration in the sampling tube [3]. There is less experience in use of the PFA-100 to assess the effect of clopidogrel, and it is uncertain whether the citrate concentration is also important in this situation. Results from the PFA-100 may also be affected by smoking, haematocrit and gender [1]. The Thrombelastograph (TEG ) Haemostasis Analyser (Haemoscope Corp., Niles, IL, USA) is a near-patient method of monitoring whole blood coagulation. Standard use of the TEG system cannot detect the effect of aspirin [4]. However, a new TEG assay has been developed specifically for this purpose (Personal communication: Haemoscope Corp., Niles, IL, USA). The use of antiplatelet medication has implications for the safety of regional anaesthesia and propensity to bleed during surgery. Further studies are needed to provide a sufficiently robust method of platelet function assessment to guide anaesthetic management.

A response to ‘Spinal anaesthesia despite combined clopidogrel and aspirin therapy in a patient awaiting lung transplantation: effects of platelet transfusion on clotting tests’

bonate in this case, the post convulsive acidosis had not resolved within 1 h, unlike other recorded acidoses of this aetiology [3]. Plasma lactate was still significantly raised. We suspect thiamine deficiency and an impaired hepatorenal function (the liver clears more than 50% of blood lactate) secondary to chronic excess alcohol intake delayed resolution of the lactic acidosis. This may explain the lack of an early rebound alkalosis suggested by Dr Land who has assumed complete metabolism of lactate to bicarbonate. This patient was transferred to a Poisons Unit within our hospital and appeared well when his postictal drowsiness reduced. Arterial blood gas analysis was performed routinely on the Poisons Unit and confirmed improvements expected in his metabolic derangement. However, there are no additional data covering the time period Dr Land specifically asks about.