D.R. Spahn

Preoperative evaluation of patients with, or at risk of, coronary artery disease undergoing non‐cardiac surgery

The increasing number of patients with coronary artery disease undergoing major non-cardiac surgery justifies guidelines concerning preoperative evaluation, stress testing, coronary angiography, and revascularization. A review of the recent literature shows that stress testing should be limited to patients with suspicion of a myocardium at risk of ischaemia, and coronary angiography to situations where revascularization can improve long-term survival. Recent data have shown that any event in the coronary circulation, be it new ischaemia, infarction, or revascularization, induces a high-risk period of 6 weeks, and an intermediate-risk period of 3 months. A 3-month minimum delay is therefore indicated before performing non-cardiac surgery after myocardial infarction or revascularization. However, this delay may be too long if an urgent surgical procedure is requested, as for instance with rapidly spreading tumours, impending aneurysm rupture, infections requiring drainage, or bone fractures. It is then appropriate to use perioperative beta-block, which reduces the cardiac complication rate in patients with, or at risk of, coronary artery disease. The objective of this review is to offer a comprehensive algorithm to help clinicians in the preoperative assessment of patients undergoing non-cardiac surgery.

Relative concentrations of haemostatic factors and cytokines in solvent/detergent-treated and fresh-frozen plasma

BACKGROUND Indications, efficacy, and safety of plasma products are highly debated. We compared the concentrations of haemostatic proteins and cytokines in solvent/detergent-treated plasma (SDP) and fresh-frozen plasma (FFP). METHODS Concentrations of the following parameters were measured in 25 SDP and FFP samples: fibrinogen (FBG), factor (F) II, F V, F VII, F VIII, F IX, F X, F XIII, von Willebrand factor (vWF), D-Dimers, ADAMTS-13 protease, tumour necrosis factor-α (TNF-α), interleukin (IL)-1β, IL-6, IL-8, and IL-10. RESULTS Mean FBG concentrations in SDP and FFP were similar, but in FFP, the range was larger than in SDP (P<0.01). Mean F II, F VII, F VIII, F IX, and F XIII levels did not differ significantly. Higher concentrations of F V (P<0.01), F X (P<0.05), vWF (P<0.01), and ADAMTS-13 (P<0.01) were found in FFP. With the exception of F VIII and F IX, the range of concentrations for all of these factors was smaller (P<0.05) in SDP than in FFP. Concentrations of TNF-α, IL-8, and IL-10 (all P<0.01) were higher in FFP than in SDP, again with a higher variability and thus larger ranges (P<0.01). CONCLUSIONS Coagulation factor content is similar for SDP and FFP, with notable exceptions of less F V, vWF, and ADAMTS-13 in SDP. Cytokine concentrations (TNFα, IL-8, and IL-10) were significantly higher in FFP. The clinical relevance of these findings needs to be established in outcome studies.

The effect of potato starch derived and corn starch derived hydroxyethyl starch on in vitro blood coagulation

We have compared the effects of progressive in vitro haemodilution (30% and 60%) with potato starch derived hydroxyethyl starch and corn starch derived hydroxyethyl starch on blood coagulation in 80 patients using thrombelastography. Both solutions significantly compromised blood coagulation as evidenced by an increase in coagulation time and decreases in angle α, maximum amplitude and coagulation index (p < 0.05). Blood coagulation was more compromised during haemodilution with potato starch derived hydroxyethyl starch as compared with corn starch derived hydroxyethyl starch (p < 0.05). When taking the effect of haemodilution with 0.9% saline into account, haemodilution with both hydroxyethyl starch solutions also augmented clot lysis (p < 0.05), with potato starch derived hydroxyethyl starch having a greater effect than corn starch derived hydroxyethyl starch (p < 0.05). We conclude that potato starch derived hydroxyethyl starch compromises in vitro blood coagulation more than corn starch derived hydroxyethyl starch.

Adaptation in anaesthesia team coordination in response to a simulated critical event and its relationship to clinical performance

BACKGROUND Recent studies in anaesthesia and intensive care indicate that a teams ability to adapt its coordination activities to changing situational demands is crucial for effective teamwork and thus, safe patient care. This study addresses the relationship between adaptation of team coordination and markers of clinical performance in response to a critical event, particularly regarding which types of coordination activities are used and which team member engages in those coordination activities. METHODS Video recordings of 15 two-person anaesthesia teams (anaesthesia trainee plus anaesthesia nurse) performing a simulated induction of general anaesthesia were coded, using a structured observation system for coordination activities. The simulation involved a critical event-asystole during laryngoscopy. Clinical performance was assessed using two separate reaction times related to the critical event. RESULTS Analyses of variance revealed a significant effect of the critical event on team coordination: after the occurrence of the asystole, team members adapted their coordination activities by spending more time on information management-a specific type of coordination activity (F(1,28)=15.17, P=0.001). No significant effect was found for task management. The increase in information management was related to faster decisions regarding how to respond to the critical event, but only for trainees and not for nurses. CONCLUSIONS Our findings support the claim that adaptation of coordination activities is related to improved team performance in healthcare. Moreover, adaptation and its relationship to team performance were found to vary with regard to type of coordination activities and team member.

Effects on coagulation of balanced (130/0.42) and non-balanced (130/0.4) hydroxyethyl starch or gelatin compared with balanced Ringer's solution: an in vitro study using two different viscoelastic coagulation tests ROTEM™ and SONOCLOT™

BACKGROUND Hydroxyethyl starch (HES) solutions compromise blood coagulation. Low molecular weight, low-substituted HES products, and electrolyte-balanced solutions might reduce this effect. We compared the effects of in vitro haemodilution on blood coagulation with a balanced 6% HES 130/0.42 solution (HES(BAL)), a saline-based 6% HES 130/0.4 solution (HES(SAL)), a balanced lactated Ringers solution (RL) and a saline-based 4% gelatin solution (GEL). METHODS Blood was obtained from 10 healthy male volunteers and diluted with the test solutions by 33% and 66%. Quality of clot formation was measured using two viscoelastic coagulation tests: SONOCLOT and activated rotation thromboelastometry ROTEM. RESULTS Of 16 parameters measured by the viscoelastic devices, we found three statistically significant differences compared with baseline for RL, but 11 for GEL, 10 for HES(SAL), and 11 for HES(BAL) in the 33% haemodilution group (P=0.01). Comparing the different solutions, we observed a significant difference between crystalloids and colloids but none between GEL and HES. In the 66% dilution group, effects on blood coagulation were increased when compared with the 33% dilution group. We found no differences in coagulation impairment between balanced and non-balanced HES products and no differences in the detection of impaired blood coagulation due to haemodilution between the two viscoelastic coagulation tests. CONCLUSIONS Both ROTEM and SONOCLOT are sensitive tests for the detection of impaired blood coagulation due to haemodilution. There are fewer effects on blood coagulation using crystalloids compared with colloids. The effects of GEL and HES are similar. There is no difference between balanced HES 130/0.42 and non-balanced HES 130/0.4.

Patient blood management is a win-win: a wake-up call

Preoperative anaemia is frequent in surgical patients and increases postoperative mortality, major morbidity, and length of hospital stay. Poorly controlled bleeding and surgical blood loss can also contribute to these outcomes. Anaemia, blood loss, and liberal transfusion triggers are the main predictors for red blood cell (RBC) transfusion. RBC transfusion in turn is an additional independent predictor for adverse outcome and has therefore been referred to as the ‘second hit’ for the recipient. Transfusion outcomes include higher mortality, more ischaemic complications, organ dysfunction, infections, delayed wound healing, and increased length of hospital stay. – 8 Transfused patients may also be more likely to develop non-Hodgkin lymphoma. Interestingly, most of these complications are found after administration of just a single RBC unit. 11 Strict application of the Bradford-Hill criteria strongly suggests that the link between transfusion and adverse outcomes is causal and not just associative. 12 A further challenge is the surveillance for newly emerging and re-emerging pathogens. Protozoan parasites in the blood donor pool cause babesiosis and Chagas disease, and transfusion-transmitted viral infections such as dengue and chikungunya represent real threats to public health systems. Recently, a transgenic mouse model demonstrated how human tau protein from injected Alzheimer’s disease brain extracts, spreads, and co-aggregates with endogenous mouse tau. These findings suggest that tau pathology may develop in the brain by a prion-like mechanism. Similar to the pathogenesis of variant Creutzfeldt–Jakob disease (vCJD), transfusion might play a role in one of the infective pathways. Transfusion of RBCs, the treatment of adverse transfusion outcomes, and expanding surveillance systems result in considerable financial burdens for all health systems in the developed world. Patient blood management (PBM) has recently been described as a concept pre-empting and significantly reducing the resort to transfusions by addressing anaemia, blood loss, and hypoxia as modifiable risk factors that may result in transfusion long before transfusion may even be considered. The three pillars of PBM—detection and treatment of preoperative anaemia, reduction in perioperative blood loss, and harnessing and optimizing the patientspecific physiological reserve of anaemia (including restrictive haemoglobin transfusion triggers) (Table 1)—have been proposed for years as a new standard of care to avoid the above described complications and costs. PBM was also adopted by the World Health Organization (WHA63.12) in 2010 as a principle to improve transfusion safety. Since then, the WHO has been urging member states ‘to promote the availability of transfusion alternatives including, where appropriate, autologous transfusion and patient blood management’. In Europe, however, few PBM programmes have been started so far. Kotzé and colleagues thus have to be congratulated for their study in the British Journal of Anaesthesia describing the implementation of such a programme in a Yorkshire hospital. Their programme was developed in three stages: first, they analysed the anaemia prevalence and transfusion rates in their centre and explored the local associations between preoperative haemoglobin, RBC Volume 108, Number 6, June 2012

Routine preoperative coagulation tests: an outdated practice?

Routine coagulation tests have been used for many years in the preoperative setting in the belief that they identify patients who may have acquired or congenital bleeding disorders, and on the assumption that testing will predict perioperative bleeding allowing treatment to be given and prevent it. Coagulation ‘screens’ typically include the prothrombin time (PT) and the activated partial thromboplastin time (APTT). Both tests were originally developed to aid in the diagnosis of inherited bleeding disorders such as haemophilia and were not intended as screening tests. Activation of coagulation can be achieved through the intrinsic or the extrinsic pathway leading to activation of the common pathway and conversion of fibrinogen to fibrin leading to clot formation. Although the cascade model of coagulation is not physiological, it is useful as a means to understand the mechanism by which traditional coagulation tests detect coagulopathies. The APTT activates plasma typically with substances such as kaolin or silica which cause activation of the contact pathway and, subsequently, the intrinsic and common coagulation pathways. A deficiency in any of these pathways will therefore prolong the APTT. The PT is activated with supraphysiological concentrations of tissue factor and detects FVII deficiency and also deficiencies in the common pathway. Both tests can also be prolonged by the presence of a lupus anticoagulant, inhibitors such as anticoagulants, and acute conditions associated with an acquired bleeding state. Inherited coagulation defects are rare. The incidence of haemophilia A and B is estimated at 1:5000 2 and 1:30 000 male births, respectively. Severe, clinically relevant, deficiencies of FII, FV, FVII, FX, and fibrinogen are even rarer with an incidence varying between 1:300 000 and 1:2 000 000, although this may be higher in populations where consanguineous marriages are more common. FXI deficiency is common in Ashkenazi Jews with a prevalence of 8% but rare in a general population. The majority of patients with these bleeding disorders will be aware of their diagnosis through either a personal or family history of bleeding and will be registered at specialized haemophilia centres. Indiscriminate screening by routine coagulation testing will therefore only very rarely identify previously undetected individuals. In contrast, prolongation of the APTT is a common occurrence with the most common reasons being mild FXII deficiency and the presence of a lupus anticoagulant, neither of which is associated with a bleeding tendency. Moderate and severe FXII deficiency was found in 2.3% of otherwise healthy Austrian blood donors and in 10.3% of patients undergoing cardiac surgery. Lupus anticoagulant can be found in 1.2–3.8% of healthy individuals, but the incidence increases with age and chronic disease, and was found in up to 30% of patients with systemic lupus erythematosus. The ability of a lupus anticoagulant to prolong the APTT or PT depends on the combination of reagents and analysers used and may therefore vary between laboratories. Other causes of a prolonged APTT not associated with a bleeding tendency include high molecular weight kininogen deficiency and prekallikrein deficiency. Finally, a normal range is calculated by the mean +2 standard deviations of measurements in healthy, non-bleeding subjects and by definition 2.5% of measurements in normal individuals will show a prolonged clotting time. Therefore, if routine coagulation testing is done to identify previously undiagnosed bleeding disorders, it is much more likely to identify a prolonged routine coagulation test that is not associated with a bleeding tendency. In practice, this can lead to further unnecessary Volume 106, Number 1, January 2011

High-frequency jet ventilation for minimizing breathing-related liver motion during percutaneous radiofrequency ablation of multiple hepatic tumours

Movements of the liver caused by spontaneous breathing (during sedation or local anaesthesia) or by ventilation during anaesthesia are a source of concern in CT-guided procedures because of the limited spatial and contrast resolution of unenhanced imaging, artifacts caused by the probes and the relatively low temporal resolution of the fluoroscopy mode. During CT-guided radiofrequency ablation (RFA), it is essential that the lesion can be visualized optimally and that the ablation probe is positioned accurately to avoid non-target injuries. We therefore used high-frequency jet ventilation and general anaesthesia to minimize ventilation-related liver movement and provide optimal conditions for a patient undergoing RFA of hepatic metastases. The technical and anaesthetic considerations are discussed, and a specific limitation of transcutaneous PCO(2) measurement during activation of the ablation is reported for the first time.

III. Fibrinogen concentrate: clinical reality and cautious Cochrane recommendation

S. Kozek-Langenecker1*, D. Fries2, D. R. Spahn3 and K. Zacharowski4 1 Department of Anaesthesia and Intensive Care, Evangelical Hospital Vienna, Austria 2 Department of General and Surgical Critical Care Medicine, Medical University Innsbruck, Austria 3 Institute of Anaesthesiology, University and University Hospital Zurich, Switzerland 4 Department of Anesthesiology, Intensive Care Medicine and Pain Therapy, University Hospital Frankfurt, Germany

Kardiovaskuläre Stressprotektion während der Anästhesieeinleitung Vergleich zwischen Clonidin und Esmolol

ZusammenfassungSowohl Alpha-2-Agonisten wie auch kardioselektive Betablocker werden für die Stressprotektion bei der endotrachealen Intubation empfohlen. Das Ziel der Studie war es, die Wirksamkeit von Clonidin und Esmolol hinsichtlich einer Reduktion der Stressantwort nach Intubation zu vergleichen. Die Patienten erhielten vor der standardisierten Anästhesieeinleitung entweder eine Clonidin- (3 μg/kg; n=20) oder eine Esmololinfusion (2 mg/kg; n=20). Vor, während und 10 min nach Intubation wurden Herzfrequenz, arterieller Blutdruck, Herzzeitvolumen, Adrenalin- und Noradrenalinplasmakonzentrationen gemessen. Der Blutdruck wurde invasiv gemessen und das Herzminutenvolumen mittels transthorakaler Echokardiographie bestimmt. Sowohl die absoluten Werte wie auch der Anstieg des arteriellen Mitteldrucks und der Noradrenalinplasmakonzentration während der Intubation waren in der Clonidingruppe signifikant geringer als in der Esmololgruppe (p<0,05). In den gewählten Dosierungen unterdrückt Clonidin den hyperdynamen und hyperadrenergen Zustand bei der endotrachealen Intubation wirksamer als Esmolol.AbstractAlpha-2-adrenoceptor-agonists as well as cardioselective betareceptor-antagonists have been shown to blunt stress response due to tracheal intubation. The purpose of our study was to investigate, whether clonidine or esmolol is more efficient to attenuate stress response due to intubation. 44 patients were randomly assigned to receive either clonidine (n=22; 3 μg/kg) or esmolol (n=22; 2 mg/kg) immediately prior to a standardized induction of anaesthesia. Heart rate, arterial blood pressure, cardiac output, epinephrine and norepinephrine plasma concentrations were measured before, during and 10 min after intubation. Blood pressure was measured invasively and cardiac output was determined by transthoracic echocardiography. Absolute values and increase of mean arterial pressure and norepinephrine plasma concentrations were significantly less in the clonidine group (p<0,05). Clonidine (3 μg/kg) is more efficient than esmolol (2 mg/kg) in blunting stress response due to endotracheal intubation.