Heart rate variability: a diagnostic and prognostic tool in anesthesia and intensive care.

The autonomic nervous system (ANS) plays an important role in the human response to various internal and external stimuli, which can modify homeostasis, and exerts a tight control on essential functions such as circulation, respiration, thermoregulation and hormonal secretion. ANS dysfunction may complicate the perioperative course in the surgical patient undergoing anesthesia, increasing morbidity and mortality, and, therefore, it should be considered as an additional risk factor during pre-operative evaluation. Furthermore, ANS dysfunction may complicate the clinical course of critically ill patients admitted to intensive care units, in the case of trauma, sepsis, neurologic disorders and cardiovascular diseases, and its occurrence adversely affects the outcome. In the care of these patients, the assessment of autonomic function may provide useful information concerning pathophysiology, risk stratification, early prognosis prediction and treatment strategies. Given the role of ANS in the maintenance of systemic homeostasis, anesthesiologists and intensivists should recognize as critical the evaluation of ANS function. Measurement of heart rate variability (HRV) is an easily accessible window into autonomic activity. It is a low-cost, non-invasive and simple to perform method reflecting the balance of the ANS regulation of the heart rate and offers the opportunity to detect the presence of autonomic neuropathy complicating several illnesses. The present review provides anesthesiologists and intensivists with a comprehensive summary of the possible clinical implications of HRV measurements, suggesting that autonomic dysfunction testing could potentially represent a diagnostic and prognostic tool in the care of patients both in the perioperative setting as well as in the critical care arena.

Prospective observational study for perioperative volume replacement with 6% HES 130/0,42, 4% gelatin and 6% HES 200/0,5 in cardiac surgery.

BACKGROUND: the constantly growing amount of different kinds of colloid fluids necessitates comparative investigations with regards to the safety and effectivity in clinical use of these preparations. Hence we compared three colloid fluids in an observational study. The objective was the exploration of the influence of these three colloids on blood coagulation, hemodynamics and renal function of the cardiac surgical patient. METHODS: we included 90 patients undergoing an elective open-heart surgery with the use of the heart-lung machine and observed them consecutively. Group 1 [gelatin 4% (n = 30)], Group 2 [HES 200/0,5 (n = 30)] and Group 3 [HES 130/0,42 (n = 30)]. We measured the perioperative volume replacement, the administration of blood- and coagulation-products, the application of catecholamines, the renal function, blood gas and the platelet aggregation using multiplate electrode analyzer (Multiplate, Dynabyte medical, Munich, Germany). RESULTS: the gelatin-group needed significantly more norepinephrine than the HES 130/0.42 group. The responsible surgeon considered the blood coagulation in the HES 200/0.5 group most frequently as impaired. Furthermore we saw a significant decrease in platelet function in the HES 200/0.5 group when performing the multiplate-analysis (ADP-and COL-test). HES 130/0.4 as well as gelatin 4% showed no significant change in platelet function. The gelatin-group and the HES 200/0.5 needed significantly more aprotinine than the HES 130/0.4 group. We saw no significant difference with regards to administration of blood and coagulation products between the three groups. The urinary excretion during the intervention was significantly higher in the HES 200/0.5 group and in the gelatin group than in the HES 130/0.4 group. CONCLUSIONS: our results confirm the lower stabilizing effect of gelatin on circulation during fluid resuscitation. The blood coagulation was mostly impaired due to HES 200/0.5 confirmed by the multiplate®-analysis as well as by different clinical findings.

Impact of platelet count on results obtained from multiple electrode platelet aggregometry (Multiplate).

OBJECTIVES: Use of potent antiplatelet drugs requires evaluation of platelet function. While platelet function in elective cases is usually assessed in a central laboratory environment, there is also an urgent need for rapid perioperative point-of-care assessment. Recently, multiple electrode platelet aggregometry has been developed and assumed to measure platelet function independent from platelet count. We tested the hypothesis that results of multiple electrode platelet aggregometry are affected by platelet count, in particular if platelet count is below normal range. METHODS: Whole blood samples from 20 healthy volunteers were prepared containing platelet concentrations of 50,000, 100,000, 150,000, 200,000, and 250,000 microl(-1) while maintaining hematocrit. Platelet aggregation was induced by collagen, thrombin receptor activating peptide 6 (TRAP-6), adenosine-diphoshate (ADP), and arachidonic acid, respectively, and aggregation was measured by multiple electrode platelet aggregometry (Multiplate). RESULTS: Results of multiple electrode platelet aggregometry significantly decreased in blood samples with platelet count below normal range. Compared to results measured in blood samples with platelet count within normal range, aggregometry results decreased by 18.4 % (p<0.001) and 37.2 % (p<0.001) in blood samples with a platelet count of 100.000 and 50.000 microl(-1), respectively. On the other hand, large interindividual variation has been observed and some blood samples showed normal results even with platelet counts of 50.000 microl(-1). CONCLUSION: The results obtained with Multiplate. Analyzer are influenced by platelet function as well as platelet count thus displaying the overall platelet aggregability within the blood sample rather than platelet function alone.

Prospective study comparing skin impedance with EEG parameters during the induction of anaesthesia with fentanyl and etomidate.

OBJECTIVE: Sympathetic stimulation leads to a change in electrical skin impedance. So far it is unclear whether this effect can be used to measure the effects of anaesthetics during general anaesthesia. The aim of this prospective study is to determine the electrical skin impedance during induction of anaesthesia for coronary artery bypass surgery with fentanyl and etomidate. METHODS: The electrical skin impedance was measured with the help of an electro-sympathicograph (ESG). In 47 patients scheduled for elective cardiac surgery, anaesthesia was induced with intravenous fentanyl 10 mug/kg and etomidate 0.3mg/kg. During induction, the ESG (Electrosympathicograph), BIS (Bispectral IndeX), BP (arterial blood pressure) and HR (heart rate) values of each patient were recorded every 20 seconds.The observation period from administration of fentanyl to intubation for surgery lasted 4 min. - RESULTS: The ESG recorded significant changes in the electrical skin impedance after administration of fentanyl and etomidate(p <0.05). During induction of anaesthesia, significant changes of BIS, HR and blood pressure were observed as well (p <0.05). CONCLUSIONS: The electrical skin impedance measurement may be used to monitor the effects of anesthetics during general anaesthesia.

[Intubation-linked dental injuries. Relevance of individually adaptable tooth protection models]. / Intubationsbedingte Zahnverletzungen. Wertigkeit individuell adaptierbarer Zahnschutzmodelle.

BACKGROUND: Tooth damage during anaesthesia could be reduced by using tooth protectors during endotracheal intubation. The effectiveness of different models was investigated using an upper jaw model. METHOD: A total of 6 individual adaptable dental protectors (Endoragard and Camo, with wax or silicone filling, respectively, Beauty pink dental wax with and without tissue inserts) were examined in three different categories. The upper jaw was covered with each dental shield and then loaded with a force of 150 N via a blade of a laryngoscope. Subsequently, force reduction was measured in axial as well as horizontal directions. Furthermore, the reduction in oral view was determined by measuring the thickness of each dental shield with a micrometer. RESULTS: The combination of Camo and silicone achieved the maximum horizontal force reduction value (39.2 N). Endoragard and silicone achieved the best axial value (21.6 N). Beauty pink wax had the thinnest dental shield (2.8 mm), whereas the combination of Camo and silicone gave the most limited view inside the oral cavity (3.8 mm). CONCLUSION: Preformed dental shields are useful for reducing the force applied to the teeth and potentially reducing the probability of tooth damage during laryngoscopy. However, the shield with the highest force reduction capability is relatively large and expensive which makes general use almost impossible. The model Beauty pink was slightly less force reducing and could be considered as an inexpensive and yet effective tool for clinical assignment.

The 'heparin lock': cause for iatrogenic coagulopathy.

BACKGROUND AND OBJECTIVE: The reasons for coagulopathy may be multiple and the identification of the underlying cause is often difficult. Recently, we identified two patients showing characteristics of heparin overdose during surgery. We hypothesised that filling a Shaldon dialysis catheter with heparin prior to closure, so-called heparin lock, might have triggered this coagulation disorder. Therefore, the aim of this in vitro study was to show whether this procedure can lead to an iatrogenic administration of heparin. METHODS: A Shaldon catheter (GamCath; Joka Kathetertechnik, Hechingen, Germany) was hung up in a container filled with NaCl solution 0.9% 5 mL and a heparin lock was simulated. Instead of using heparin solution we injected 1 mL of a KCl solution (1 mol L(-1)) into the Shaldon catheter, because the measurement of the potassium concentration is faster and more reliable than that of heparin. Ten measurements were taken after fast (0.5 s) and slow (3 s) injection speeds. RESULTS: Although the catheter volume is specified as 1.07 mL, an amount up to 0.51 mL KCl solution on average was detectable in the solution after locking the catheter with 1 mL KCl solution. CONCLUSIONS: Following a heparin lock a considerable amount of the injected solution is accidentally administered to the patient. Only 49.1% of the injected volume may remain in the Shaldon catheter. This could lead to an increased risk of coagulopathy.

Immunoreactivity of Thomsen-Friedenreich (TF) antigen in human neoplasms: the importance of carrier-specific glycotope expression on MUC1.

On the basis of their known fine specificities we evaluated the immunohistochemical marker qualities of two monoclonal antibodies (mabs) defining the tumor-associated TF disaccharide Gal beta 1-3 GalNAc. This antigen is expressed in certain tumors in correlation with prognosis and metastasis. The reactivity of one of these mabs (A78-G/A7) depends on clustered TF disaccharides (glycosylation at vicinal Ser/Thr positions) while the other--mab BW835--has been characterized to bind specifically to TF disaccharide linked to a motif within the MUC1 repeat. Therefore, mab BW835 represents an interesting tool for the identification of tumor-associated glycoforms of MUC1, which are involved in tumor progression and metastasis, but also in the recognition of tumor cells by cytotoxic T cells. As references the TF-binding lectins from peanut (PNA) and Artocarpus integrifolia (jacalin) were applied. The binding patterns of these immunoreagents were strikingly distinct. Mab BW835 showed a significantly stronger reactivity than mab A78-G/A7, especially in gastric, mammary, pancreatic, thyreoideal, renal and bladder carcinomas. PNA and jacalin receptors exhibited an expression in the majority of all cancer types, with the exception of seminoma and glioblastoma/sarcoma. These results can be explained by the broader fine specificities of the lectins. Furthermore, a strong expression of MUC1-bound TF antigen is indicated by the staining pattern of mab BW835. The marker qualities of both antigens, TF and MUC1, are combined in the binding specificity of BW835, and hence this antibody may have a high impact for the immunodetection of these tumor-associated antigens.

Histopathological subtypes and prognosis of gastric cancer are correlated with the expression of mucin-associated sialylated antigens: Sialosyl-Lewis(a), Sialosyl-Lewis(x) and sialosyl-Tn.

The expression of three sialylated mucin-associated antigens - sialosyl-Lewisa (SLEA), sialosyl-Lewisx (SLEX) and sialosyl-Tn (STN) - and their correlation with the TNM stage, histopathological growth pattern and prognosis was investigated in a series of 127 gastric carcinomas. Various classification systems (pTNM, WHO and Laurén) did not display any correlation with an expression of the sialomucin antigens under study. SLEA reactivity was strongly associated with an unfavorable outcome of the total population, whereas SLEX and STN did not exert such an impact. However, in the subgroups of pTNM stage I as well as pN0 patients, SLEA and SLEX reactivity of the tumors was associated with a worse prognosis. In the subgroup of diffuse-type cancers as defined according to Laurén's classification, the expression of all three antigens indicated a worsening of the prognosis.