Anaesthesia, 2010, 65, pages 857–866 Correspondence . ....................................................................................................................................................................................................................
blood samples pre-treated with heparinase showed decreasing clot amplitude resembling a fibrinolytic pattern (Fig. 6). This could have been due to true fibrinolysis or to disconnection of the undissolved clot from the pin or the cuvette during platelet-mediated clot retraction [5]. We felt that true fibrinolysis was unlikely, as none of our patients with a fibrinolytic TEG pattern had bleeding problems clinically or were receiving anticoagulant therapy. Moreover, inspection of the clot did not reveal signs of fibrinolysis and we detected visible disconnection of the clot from the pin or the cuvette. We performed TEG analysis (Haemoscope Corp., Niles, Illinois, USA) of a blood sample obtained from a healthy volunteer and added 5000 IU streptase (CSL Behring GmbH, Hattersheim am Main, Germany) into the cuvette to trigger artificial fibrinolysis (Fig. 7). The resulting fibrinolytic pattern resembled that recorded in some of our heparinase-treated samples, and upon inspection no blood clot was found in the cuvette. We conclude that TEG in blood samples pre-treated with heparinase can result in false positive fibrinolytic patterns. We recommend careful interpretation of such samples in the context of the patients’ clinical condition or the elimination of the requirement for
Figure 6 Thromboelastography traces of native (grey) and. heparinase-treated (black) blood samples.
Figure 7 Thromboelastography trace of normal blood modified by streptase to trigger artificial fibrinolysis.
heparinase by not using heparin in the catheter flush system or discarding the first aspirated volume to eliminate the added heparin [6]. M. Durila T. Kalincik K. Cvachovec Charles University Hospital, Prague, Czech Republic R. Filho ProCardiaco Hospital, Rio de Janeiro, Brasil Email:
[email protected]
This work was supported by a grant from Charles University. No other competing interests declared. Published with the volunteer’s written consent.
References 1 Coppell JA, Thalheimer U, Zambruni A, et al. The effects of unfractionated heparin, low molecular weight heparin and danaparoid on the thromboelastogram (TEG): an in-vitro comparison of standard and heparinase-modified TEGs with conventional coagulation assays. Blood Coagulation and Fibrinolysis 2006; 17: 97–104. 2 Schulte A, Clark M. The effect of line flush heparin contamination on thromboelastograph trace analysis. Anaesthesia 2008; 63: 1381–2. 3 Ti LK, Cheong KF, Chen FG. Prediction of excessive bleeding after coronary artery bypass graft surgery: the influence of timing and heparinase on thromboelastography. Journal of Cardiothoracic and Vascular Anesthesia 2002; 16: 545–50. 4 Harding SA, Mallett SV, Peachey TD, Cox DJ. Use of heparinase modified thrombelastography in liver transplantation. British Journal of Anaesthesia 1997; 78: 175–9. 5 Katori N, Tanaka KA, Szlam F, Levy JH. The effects of platelet count on clot retraction and tissue plasminogen activator-induced fibrinolysis on thrombelastography. Anesthesia and Analgesia 2005; 100: 1781–5. 6 Durila M, Kalincik T, Pacakova Z, Cvachovec K. Discard volume necessary for elimination of heparin flush effect on thromboelastography. Blood Coagulation and Fibrinolysis 2010; 21: 192–5.
2010 The Association of Anaesthetists of Great Britain and Ireland
doi: 10.1111/j.1365-2044.2010.06441.x
Colour coding: a must for extraglottic airway devices
We read with interest the recent letters highlighting the problems associated with ambiguous or inaccurate colour coding of gas cylinders [1, 2]. When correctly applied, colour coding plays an important role in avoiding mistakes due to human error [3], as critical information about the device is instantly available. Unfortunately, colour coding has only been introduced for gas cylinders [4], intravenous cannulas and needles [5]. We consider that extraglottic airway devices should be added to this woefully short list. There is no consistency in the colour coding of extraglottic airway devices. Although some manufacturers use a sizespecific colour on the sterile package, the pilot balloon or the connector; these colour codes vary among manufacturers, and most use none. All manufacturers provide information in the form of markings, symbols and text along the airway tube, but these are often difficult to see once the device is inserted. The portions that remain visible (i.e. the pilot balloon and connector) are too small to record and read detailed information. The lack of instantly available information is particularly problematic in emergency situations when quick decisions must be made about airway management. On two occasions we have experienced delays in intubation via an extraglottic airway device due to lack of instant information about size. Although weight-based size recommendations vary, most manufacturers use similar size scales. We urge manufacturers to liase with the International Organization for Standards to develop size-specific colour codes. These colours should be used on the sterile package, pilot balloon, cuff deflator valve and the connector. T. C. R. V. van Zundert Maastricht University Medical Centre, Maastricht, The Netherlands J. R. Brimacombe James Cook University, Cairns Hospital, Cairns, Queensland, Australia Email:
[email protected]
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Correspondence Anaesthesia, 2010, 65, pages 857–866 . ....................................................................................................................................................................................................................
No external funding and no competing interests declared.
References 1 Crombie N. Confusing and ambiguous labelling of an oxygen cylinder. Anaesthesia 2009; 64: 98. 2 Taylor NJ, Davison M. Inaccurate colour coding of medical gas cylinders. Anaesthesia 2009; 64: 690.
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3 Webster CS. Human psychology applies to doctors too. Anaesthesia 2000; 55: 929–30. 4 British Standards Institution. BS EN1089-3:2004. Transportable Gas Cylinders – Gas Cylinder Identification (Excluding LPG) – Part 3: Colour Coding British Standards Institute. http://shop.bsigroup.com/ (accessed 03 ⁄ 05 ⁄ 2010).
5 International Organization for Standardisation. ISO 6009: Hypodermic needles for single use – colour coding for identification, 1992. http:// www.iso.org/iso/iso_catalogue.htm (accessed 03 ⁄ 05 ⁄ 2010). doi: 10.1111/j.1365-2044.2010.06442.x
2010 The Association of Anaesthetists of Great Britain and Ireland
