Showing papers by "Niels Rahe-Meyer published in 2008"

Endocrine stress response and inflammatory activation during CABG surgery. A randomized trial comparing remifentanil infusion to intermittent fentanyl.

Abstract: Background and objectiveOur aim was to compare a continuous infusion of remifentanil with intermittent boluses of fentanyl as regards the perioperative hormonal stress response and inflammatory activation in coronary artery bypass graft patients under sevoflurane-based anaesthesia.MethodsIn all, 42 patients undergoing coronary artery bypass grafting with cardiopulmonary bypass were prospectively randomized to a fentanyl group (n = 21, total fentanyl dose 2.6 ± 0.3 mg), or a remifentanil group (n = 21, infusion rate 0.25 μg kg−1 min−1). Haemodynamics, plasma levels of epinephrine, norepinephrine, antidiuretic hormone, adrenocorticotropic hormone, cortisol, complement activation (C3a, C5b-9), interleukin (IL)-6, IL-8 and tumour necrosis factor-α were measured at T1: baseline, T2: intubation, T3: sternotomy, T4: 30 min on cardiopulmonary bypass, T5: end of surgery and T6: 8 h postoperatively. Troponin T and creatine kinase-MB were measured postoperatively.ResultsPatients in the remifentanil group were extubated significantly earlier than fentanyl patients (240 ± 182 min vs. 418 ± 212 min, P = 0.006). Stress hormones 30 min after start of cardiopulmonary bypass showed higher values in the fentanyl group compared to the remifentanil group (antidiuretic hormone (ADH): 39.94 ± 30.98 vs. 11.7 ± 22.8 pg mL−1, P = 0.002; adrenocorticotropic hormone: 111.5 ± 116.8 vs. 21.81 ± 24.71 pg mL−1, P = 0.01; cortisol 185 ± 86 vs. 131 ± 82 ng mL−1, P = 0.04). The interleukins were significantly higher at some perioperative time points in the fentanyl group compared to the remifentanil group (tumour necrosis factor: T5: 3.57 vs. 2.37; IL-6: T5: 4.62 vs. 3.73; and IL-8: T5: 4.43 vs. 2.65 and T6: 2.61 vs. 1.13). However, cardiopulmonary bypass times and aortic cross-clamp times were longer in the fentanyl group, which may to some extent account for the differences.ConclusionsThe perioperative endocrine stress response was attenuated in patients supplemented with continuous remifentanil infusion as compared to intermittent fentanyl.

Whole blood coagulation measured by modified thrombelastography (ROTEM) is impaired in infants with congenital heart diseases

Abstract: Patients with congenital heart disease (CHD) often do have a variety of coagulation abnormalities that results in bleeding diathesis. Our study aimed to determine the impact of cyanosis and CHD on modified thrombelastography parameters, compared with children without CHD. Preoperative blood samples were taken for TEM analyses from a total of 51 infants scheduled for surgery. The following groups were examined: normal patients without CHD, acyanotic patients with acyanotic CHD, and cyanotic patients with CHD and with preoperative hemoglobin values higher than 15 g dl(-1). Mean values of all patient groups as well as all individual values of normal patients were within their normal ranges. Within these limits, however, clots were significantly inferior in cyanotic patients (worse mean values of eight out of 10 measured TEM parameters representing the intrinsic, extrinsic, and plasmatic pathways of coagulation) and in acyanotic patients (two out of 10 TEM parameters). Individually, pathological TEM parameters were found in seven (41%) cyanotic patients (P=0.003; vs. normal patients) and in three (17%) acyanotic patients (P=0.01). More than one abnormal TEM coagulation parameter was found in four patients, all of them cyanotic patients. Hyperfibrinolysis was detected in one patient, a cyanotic patient. The present investigation confirms previous findings that in patients with CHD the heart defect itself compromises coagulation monitored with TEM, but in addition, we demonstrate that cyanosis and/or polycythemia exert the essential negative impact on hemostasis. Preoperative hyperfibrinolysis detected with TEM seems to play no important role.

An Evaluation of Cyclooxygenase-1 Inhibition Before Coronary Artery Surgery : Aggregometry Versus Patient Self-Reporting

Abstract: BACKGROUND:Platelet dysfunction due to antiplatelet therapy contributes to perioperative bleeding. Several trials investigating the influence of aspirin intake within the 5 days before surgery reported that transfusion requirements were either increased or not significantly affected by aspirin intak

Prospective Investigation into the Influence of Various Stressors on Skin Impedance

Abstract: Background The control mechanisms during general anesthesia include circulation parameters and vegetative reactions. A possible way to quantify vegetative reactions is to measure the impedance of the skin. An activation of the eccrine sweat glands via sympathetic sudomotor fibers induces a secretion of sweat, which generates a drop in skin impedance. The aim of the present study was to investigate the influence which different stressors and measurement electrodes have upon skin impedance.

Influence of the sample anticoagulant on the measurements of impedance aggregometry in cardiac surgery.

Abstract: Background: The standard method of assessment of platelet function is represented by light transmission aggregometry (LTA), performed in citrated platelet-rich plasma (PRP). With LTA, decrease and subsequent post-cardiopulmonary bypass (CPB) recovery of platelet function have been reported during cardiac surgery. Multiple electrode aggregometry (MEA) may be used as point-of-care method to monitor perioperative changes in platelet function. Since MEA assesses macroaggregation which is infl uenced by the plasmatic levels of unbound calcium, citrate may be inadequate as anticoagulant for MEA. We used citrate and heparin for MEA samples, to see with which anticoagulant the intraoperative decrease and postoperative recovery in platelet function previously described with other aggregometric methods in cardiac surgery may be observed with MEA. Methods: Blood was obtained from 60 patients undergoing routine cardiac surgery and the samples were collected in standard tubes containing unfractionated heparin (50 U/mL) or trisodium citrate (3.2%). The samples were obtained before CPB, at 30 minutes on CPB, end of CPB and on the fi rst postoperative day. MEA was performed using the Multiplate ® analyzer. Collagen (COLtest, 100 μg/mL) and TRAP-6 (thrombin receptor activating peptide, TRAPtest, 1mM/mL) were used as aggregation agonists. Results: Platelet aggregometric response decreased significantly during CPB. Platelet aggregation assessed using TRAP-6 as agonist on heparinized blood signifi cantly correlated with the duration of CPB (r = −0.41, p = 0.001, 2-tailed Pearson test). The aggregometric analysis performed on the fi rst postoperative day showed a signifi cant recovery in platelet activity in the samples containing heparin (increase from 30 ± 22 U to 46 ± 27 U for the COLtest and from 70 ± 34 U to 95 ± 32 U for the TRAPtest, p � 0.001, Student’s t-test), while no signifi cant recovery of platelet function could be established in the MEA measurements performed with citrated blood. Conclusions: The choice of blood sample anticoagulant used for impedance aggregometry infl uenced the platelet aggregation response. Postoperative platelet function recovery was only detected in the heparinized samples. Heparin seems to be better suited than citrate for the analysis of impedance aggregometry in heart surgery.

Aerosol delivery by an ultrasonic nebulizer during different mechanical ventilation settings in a lung model--a pilot study.

Abstract: Aerosol delivery of Iloprost is a promising therapeutic approach. The aim of this study was to determine the output of an ultrasonic nebulizer in different ventilation set-ups at the tip of different endotracheal tubes. Method: In set-up A, an ultrasonic nebulizer was connected directly to the endotracheal tube. In set-up B, the nebulizer was incorporated into the inspiratory limb of the ventilator circuit; a bypass arrangement allowed to selectively direct the exspiratory air discharged from the model lung. The test lungs were ventilated through a standard endotracheal tube (ET) and through a double-lumen tube (DLT). The nebulizer was fi lled with 5 ml of a Tc-99m 0.9%-NaCl solution. After nebulization, distribution of radioactivity was detected by gamma scintigraphy. Results: Set-up A, ventilation in volume-controlled mode (VCV) via an ET: Delivered dose (1.61 ± 0.41 ml), nebulization time 10.13 ± 1.71 min. Set-up A, pressure-controlled ventilation (PCV), via a DLT: Delivered dose (1.33 ± 0.88 ml), nebulization time 13.27 ± 2.58 min. Set-up B, VCV mode via an ET: Delivered dose (1.57 ± 0.44 ml), nebulization time (25.9 ± 3.8 min). Set-up B, PCV mode, via a DLT: Delivered dose (1.3 ± 0.17 ml), nebulization time (25.6 ± 4.0 min). Set-up B did not yield a signifi cantly higher output (p 0.05), but the nebulization time was signifi cantly longer (p 0.05) compared with set-up A. Conclusion: Set-ups which involve connecting the nebulizer directly to an ET or a DLT exhibit suffi cient output of aerosol and short nebulization times.

Complex myograph allows the examination of complex muscle contractions for the assessment of muscle force, shortening, velocity, and work in vivo.

Abstract: The devices used for in vivo examination of muscle contractions assess only pure force contractions and the so-called isokinetic contractions. In isokinetic experiments, the extremity and its muscle are artificially moved with constant velocity by the measuring device, while a tetanic contraction is induced in the muscle, either by electrical stimulation or by maximal voluntary activation. With these systems, experiments cannot be performed at pre-defined, constant muscle length, single contractions cannot be evaluated individually and the separate examination of the isometric and the isotonic components of single contractions is not possible. The myograph presented in our study has two newly developed technical units, i.e. a). a counterforce unit which can load the muscle with an adjustable, but constant force and b). a length-adjusting unit which allows for both the stretching and the contraction length to be infinitely adjustable independently of one another. The two units support the examination of complex types of contraction and store the counterforce and length-adjusting settings, so that these conditions may be accurately reapplied in later sessions. The measurement examples presented show that the muscle can be brought to every possible pre-stretching length and that single isotonic or complex isometric-isotonic contractions may be performed at every length. The applied forces act during different phases of contraction, resulting into different pre- and after-loads that can be kept constant – uninfluenced by the contraction. Maximal values for force, shortening, velocity and work may be obtained for individual muscles. This offers the possibility to obtain information on the muscle status and to monitor its changes under non-invasive measurement conditions. With the Complex Myograph, the whole spectrum of a muscle's mechanical characteristics may be assessed.

Multicentric evaluation of single shot reagents for thromboelastometry (ROTEM®): 6AP2-9

Abstract: ing it by FFP. In one series,autologous erythrocyte concentrate was added as needed to maintain Htc>0,2. Analysis was performed before and after Htc correction with TRAP-6(32μM), arachidonic acid (0,5mM), ADP (6,4μm) and collagen (3,2μg/ml) as activator. Multiple linear regression was performed to look for the association between Multiplate aggregation and PC, Htc and fibrinogen concentration. Results are described as median (75th/25th) percentile,statistical significance was considered at p<0,05. Results and Discussion: PC and Htc before Htc correction decreased continously from 219(238/207)/nl to 36(39/27)/nl and from 46(48/44)% to 7(9/5)%, respectively. Adding autologous red cells to the diluted samples maintained Htc levels above 19% and did not alter PC.