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Biomedical subjects

Berthold Bein

Publications and source records attributed to Berthold Bein.

At least 19 recordsLinked to original sources
PubMed2006

Brain tissue oxygen pressure and cerebral metabolism in an animal model of cardiac arrest and cardiopulmonary resuscitation.

OBJECTIVE: Direct measurement of brain tissue oxygenation (PbtO2) is established during spontaneous circulation, but values of PbtO2 during and after cardiopulmonary resuscitation (CPR) are unknown. The purpose of this study was to investigate: (1) the time-course of PbtO2 in an established model of CPR, and (2) the changes of cerebral venous lactate and S-100B. METHODS: In 12 pigs (12-16 weeks, 35-45 kg), ventricular fibrillation (VF) was induced electrically during general anaesthesia. After 4 min of untreated VF, all animals were subjected to CPR (chest compression rate 100/min, FiO2 1.0) with vasopressor therapy after 7, 12, and 17 min (vasopressin 0.4, 0.4, and 0.8 U/kg, respectively). Defibrillation was performed after 22 min of cardiac arrest. After return of spontaneous circulation (ROSC), the pigs were observed for 1h. RESULTS: After initiation of VF, PbtO2 decreased compared to baseline (mean +/- SEM; 22 +/- 6 versus 2 +/- 1 mmHg after 4 min of VF; P < 0.05). During CPR, PbtO2 increased, and reached maximum values 8 min after start of CPR (25 +/- 7 mmHg; P < 0.05 versus no-flow). No further changes were seen until ROSC. Lactate, and S-100B increased during CPR compared to baseline (16 +/- 2 versus 85 +/- 8 mg/dl, and 0.46 +/- 0.05 versus 2.12 +/- 0.40 microg/l after 13 min of CPR, respectively; P < 0.001); lactate remained elevated, while S-100B returned to baseline after ROSC. CONCLUSIONS: Though PbtO2 returned to pre-arrest values during CPR, PbtO2 and cerebral lactate were lower than during post-arrest reperfusion with 100% oxygen, which reflected the cerebral low-flow state during CPR. The transient increase of S-100B may indicate a disturbance of the blood-brain-barrier.

Animals↗
PubMed2006

Entropy.

The concept of entropy, originally derived from thermodynamics, has been successfully applied to EEG analysis. Various entropy algorithms have been used in clinical studies, but until now a commercially available monitor exists only for spectral entropy. By calculating two distinct values for the EEG dominated part of the spectrum (state entropy, SE) and the total spectrum (response entropy, RE), the M-Entropy module claims to provide useful information regarding the cortical state of the patient as well as an indirect measure of adequacy of analgesia. Generally, entropy has been studied for quantification of anaesthetic drug effect for various GABA-ergic i.v. induction agents and volatile anaesthetics like propofol and sevoflurane and overall was found comparable to the current clinical gold standard bispectral index (BIS). Entropy guidance may not be used during ketamine or nitrous oxide administration, since there is no reliable correlation to the patient's state of consciousness. The usefulness of RE as a surrogate for increased EMG activity due to painful stimulation has not been proven so far.

Analgesia↗
PubMed2006

Interaction of the amyloid precursor like protein 1 with the alpha2A-adrenergic receptor increases agonist-mediated inhibition of adenylate cyclase.

Alpha2-adrenergic receptor agonists exert potent analgesic and sedative/hypnotic effects. In addition, they have been shown to be neuroprotective, but the mechanisms of these actions are still poorly defined. To isolate proteins that may control alpha2-adrenergic receptor function or trafficking, we performed a two-hybrid screen using the carboxy-terminal fourth intracellular tail of the alpha2A-adrenergic receptor as bait. This screen identified the amyloid precursor like protein 1 (APLP1), a homologue of the beta-amyloid precursor protein involved in Alzheimer's disease, as alpha2A-adrenergic receptor-binding protein. GST affinity chromatography revealed that APLP1 specifically interacts with all three human alpha2-adrenergic receptor subtypes and deletion mutant analysis confined the APLP1 domain involved in binding to alpha2-adrenergic receptors to the 13 amino acid residues Ser599-Ala611. Coimmunoprecipitations of transiently transfected cells with epitope-tagged APLP1 and alpha2-adrenergic receptors confirmed the interaction. Agonist treatment tended to increase the amount of alpha2A-adrenergic receptor associated with APLP1 while coimmunoprecipitations were not affected by the state of receptor phosphorylation or cotransfection of arrestin-3. Confocal laser microscopy showed that APLP1 causes a considerable shift of the alpha2A-adrenergic receptor localization from plasma membrane to intracellular compartments. Furthermore, cotransfection of alpha2A-adrenergic receptor and APLP1 into HEK293 cells significantly increased norepinephrine mediated inhibition of adenylate cyclase activity. These results suggest a possible role of APLP1 in regulation of alpha2A-adrenergic receptor trafficking. Moreover, we speculate that this interaction may present one mechanism by which alpha2-adrenergic receptor agonists exert their neuroprotective effects.

Adenylyl Cyclase Inhibitors↗
PubMed2006

[Preoperative identification of cardiac risk patients and perioperative management].

The demographic trend challenges anaesthesiologists with a growing number of elderly requiring surgery. The anaesthetist needs to identify risk patients and to optimize his strategies for perioperative management. The present article gathers the current data and summarizes effective strategies for anaesthesia in patients with ischemic heart disease.

Anesthesia↗
PubMed2006

[Clinical management of the difficult airway].

Difficult airway management is among the key requirements in routine anaesthesia. Failures to secure the airways resulting in a "Cannot intubate, Cannot ventilate" situation can drastically increase morbidity and mortality of patients within a very short time. Therefore, an algorithm for management of the expected and unexpected difficult airway describing the sequence of various procedures, adapted to internal standards and to techniques that are available, has to be provided by each anaesthesia department. This not only facilitates the preparation of equipment and the training of personnel, but also ensures efficient decision making under time pressure.

Anesthesia↗
PubMed2006

Heart rate variability predicts severe hypotension after spinal anesthesia.

BACKGROUND: Hypotension due to vasodilatation after spinal anesthesia (SA) may be harmful. Heart rate variability, an indirect measure of autonomic control, may predict hypotension. METHODS: One hundred patients were studied. Retrospectively, heart rate variability was analyzed in 30 patients, classified depending on the lowest systolic blood pressure (SBP) after SA. Seventy patients were studied prospectively, assigned to one of two groups by their low to high frequency ratio (LF/HF) before SA. Sensitivity and specificity of LF/HF for prediction of decrease of SBP greater 20% of baseline were tested. RESULTS: Retrospective analysis showed differences of LF/HF depending on the degree of hypotension after SA. Prospective analysis demonstrated significant differences of SBP after SA depending on baseline LF/HF (mean +/- SD): low LF/HF (1.3 +/- 0.7) = > SBP: 91 +/- 8% of baseline versus high LF/HF (5.5 +/- 2.4) = > SBP: 66 +/- 10% of baseline (P < 0.05). Baseline LF/HF as well as high frequency and proportional decrease of SBP after SA correlated significantly, in contrast to baseline hemodynamic parameters heart rate and SBP. A receiver operator curve characteristic analysis showed a sensitivity and specificity of LF/HF > 2.5 of 85% to predict SBP decrease of greater than 20% of baseline after SA. CONCLUSIONS: Heart rate variability analysis before SA may predict hypotension after SA with high sensitivity and specificity. LF/HF may be a tool to detect patients at high risk of hypotension due to SA. This indicates that the predictive value of LF/HF is superior to established predictors.

Aged↗
PubMed2006

Heart rate variability-guided prophylactic treatment of severe hypotension after subarachnoid block for elective cesarean delivery.

BACKGROUND: Baseline low-to-high frequency ratio (LF/HF) of heart rate variability predicted hypotension after subarachnoid block (SAB). LF/HF-guided treatment of hypotension with vasopressors or colloids was investigated. METHODS: In 80 women scheduled to undergo cesarean delivery during SAB, LF/HF and systolic blood pressure (SBP) were analyzed. Patients were randomly assigned to a control group (n = 40) or a treatment group (n = 40). Control patients were assigned by their baseline LF/HF to one of two subgroups: LF/HF less than 2.5 or LF/HF greater than 2.5. Treatment patients with baseline LF/HF greater than 2.5 were treated with vasopressor infusion right after SAB (n = 20) or colloid prehydration until LF/HF decreased below 2.5 (n = 20). The incidences of hypotension (SBP < 80 mmHg) and hypertension (SBP > 140 mmHg) were investigated. LF/HF is presented as median and range, and SBP is presented as mean +/- SD. RESULTS: Three of 17 control patients with low baseline LF/HF (1.7 [1.3/1.8]) demonstrated hypotension, and mean SBP remained stable (lowest SBP = 105 +/- 14 mmHg). In contrast, 20 of 23 control patients with high baseline LF/HF (3.8 [3.3/4.8]; P < 0.0001 vs. low baseline LF/HF) demonstrated hypotension after SAB: lowest SBP = 78 +/- 15 mmHg (P < 0.0001 vs. lowest SBP of control group with low baseline LF/HF). LF/HF-guided vasopressor therapy prevented hypotension in 19 of 20 patients: baseline SBP = 123 +/- 15 mmHg, lowest SBP = 116 +/- 17 mmHg. Mean prophylactic colloid infusion of 1,275 +/- 250 ml reduced elevated baseline LF/HF from 5.4 (4.1/7.5) to 1.3 (0.8/1.59) (P < 0.0001). Hypotension was prevented in 17 of 20 patients: baseline SBP = 115 +/- 13 mmHg, lowest SBP = 104 +/- 19 mmHg. No hypertensive episode was recognized. CONCLUSIONS: LF/HF may be a tool to guide prophylactic therapy of patients at high risk for hypotension after SAB. Vasopressor therapy tended to be more effective compared with colloid prehydration.

Adult↗
PubMed2006

Propofol infusion syndrome in anaesthesia and intensive care medicine.

PURPOSE OF REVIEW: Propofol infusion syndrome is a rare but often fatal syndrome, characterized by lactacidosis, lipaemic plasma and cardiac failure, associated with propofol infusion over prolonged periods of time. As propofol is used worldwide, knowledge of propofol infusion syndrome is essential for all anaesthesiologists and intensive care physicians. This review will provide an update on reported cases, and describe recent findings relevant to the pathophysiology and clinical presentation of propofol infusion syndrome. RECENT FINDINGS: Case reports of propofol infusion syndrome have contributed new pathophysiological evidence. Reported cases of similar syndromes may represent initial propofol infusion syndrome, and may help to identify further risk factors such as low carbohydrate supply and early warning signs such as lactacidosis. Newly identified gene defects mimicking propofol infusion syndrome may elicit the underlying genetic susceptibility. Recommendations for the limitation of propofol use have been devised by various institutions. SUMMARY: Propofol infusion syndrome must be kept in mind as a rare but highly lethal complication of propofol use, not necessarily confined to the prolonged use of propofol. Dose limitations must be adhered to, and early warning signs such as lactacidosis should lead to the immediate cessation of propofol infusion.

Acidosis↗
PubMed2006

A comparison of transcranial Doppler with near infrared spectroscopy and indocyanine green during hemorrhagic shock: a prospective experimental study.

INTRODUCTION: The present study was designed to compare cerebral hemodynamics assessed using the blood flow index (BFI) derived from the kinetics of the tracer dye indocyanine green (ICG) with transcranial Doppler ultrasound (TCD) in an established model of hemorrhagic shock. METHODS: After approval from the Animal Investigational Committee, 20 healthy pigs underwent a simulated penetrating liver trauma. Following hemodynamic decompensation, all animals received a hypertonic-isooncotic hydroxyethyl starch solution and either arginine vasopressin or norepinephrine, and bleeding was subsequently controlled. ICG passage through the brain was monitored by near infrared spectroscopy. BFI was calculated by dividing maximal ICG absorption change by rise time. Mean blood flow velocity (FVmean) of the right middle cerebral artery was recorded by TCD. FVmean and BFI were assessed at baseline (BL), at hemodynamic decompensation, and repeatedly after control of bleeding. RESULTS: At hemodynamic decompensation, cerebral perfusion pressure (CPP), FVmean and BFI dropped compared to BL (mean +/- standard deviation; CPP 16 +/- 5 mmHg versus 70 +/- 16 mmHg; FVmean 4 +/- 5 cm x s(-1) versus 28 +/- 9 cm x s(-1); BFI 0.008 +/- 0.004 versus 0.02 +/- 0.006; p < 0.001). After pharmacological intervention and control of bleeding, FVmean and BFI increased close to baseline values (FVmean 23 +/- 9 cm x s(-1); BFI 0.02 +/- 0.01), respectively. FVmean and BFI were significantly correlated (r = 0.62, p < 0.0001). CONCLUSION: FVmean and BFI both reflected the large variations in cerebral perfusion during hemorrhage and after resuscitation and were significantly correlated. BFI is a promising tool to monitor cerebral hemodynamics at the bedside.

Animals↗
PubMed2006

Cerebral metabolism assessed with microdialysis in uncontrolled hemorrhagic shock after penetrating liver trauma.

In a porcine model of uncontrolled hemorrhagic shock, we evaluated the effects of fluid resuscitation versus arginine vasopressin (AVP) combined with hypertonic-hyperoncotic hydroxyethyl starch solution (HHS) on cerebral perfusion pressure (CPP) and on cerebral metabolism using intracerebral microdialysis. Sixteen anesthetized pigs were subjected to uncontrolled liver bleeding until hemodynamic decompensation, followed by resuscitation using either fluid (n = 8) or AVP/HHS (n = 8). Thirty minutes after drug administration, bleeding was controlled by manual compression, and colloid and crystalloid solutions were administered in both groups. All surviving animals were observed for one hour. After hemodynamic decompensation, fluid resuscitation resulted in a smaller increase of CPP than did AVP/HHS (mean +/- sem; 24 +/- 5 vs 45 +/- 7 mm Hg; P < 0.01). Mean (+/- sem) cerebral venous partial pressure of oxygen was significantly decreased (P < 0.01) 5 min after fluid compared with 5 min after AVP/HHS administration (36 +/- 3 vs 64 +/- 4 torr). Cerebral metabolism was comparable in both groups. In conclusion, AVP/HHS proved to be superior to fluid in the initial phase of therapy with respect to CPP and cerebral oxygenation, but was comparable to fluid regarding cerebral metabolism and secondary cell damage in surviving animals.

Animals↗
PubMed2005

Heart rate variability predicts severe hypotension after spinal anesthesia for elective cesarean delivery.

BACKGROUND: Hypotension due to vasodilation during subarachnoid block (SAB) for elective cesarean delivery may be harmful. Heart rate variability (HRV), reflecting autonomic control, may identify patients at risk of hypotension. METHODS: Retrospectively, HRV was analyzed in 41 patients who were classified into one of three groups depending on the decrease in systolic blood pressure (SBP): mild (SBP > 100 mmHg), moderate (100 > SBP > 80 mmHg), or severe (SBP < 80 mmHg). Prospectively, HRV and hemodynamic data of 19 patients were studied. Relative low frequency (LF), relative high frequency (HF), and LF/HF ratio were analyzed. RESULTS: Retrospective analysis of HRV showed a significantly higher sympathetic and lower parasympathetic drive in the groups with moderate and severe compared with mild hypotension before SAB (median, 25th/75th percentiles): LF/HF: mild: 1.2 (0.9/1.8), moderate: 2.8 (1.8/4.6), P < 0.05 versus mild; severe: 2.7 (2.0/3.5), P < 0.05 versus mild. Results were confirmed by findings of LF and HF. Prospectively, patients were grouped according to LF/HF before SAB: low-LF/HF: 1.5 (1.1/2.0) versus high-LF/HF: 4.0 (2.8/4.7), P < 0.05; low-LF: 58 +/- 9% versus high-LF: 75 +/- 10%, P < 0.05; low-HF: 41 +/- 10% versus high-HF: 25 +/- 10%, P < 0.05. High-risk patients had a significantly lower SBP after SAB (76 +/- 21 vs. 111 +/- 12 mmHg; P < 0.05). CONCLUSIONS: Retrospectively analyzed HRV of patients scheduled to undergo elective cesarean delivery during SAB showed significant differences depending on the severity of hypotension after SAB. Preliminary findings were prospectively confirmed. High LF/HF before SAB predicted severe hypotension. Preoperative HRV analysis may detect patients at risk of hypotension after SAB.

Adult↗
PubMed2005

Overlapping induction of anesthesia: an analysis of benefits and costs.

BACKGROUND: Overlapping induction (OI), i.e., induction of anesthesia with an additional team while the previous patient is still in the operating room (OR), was investigated. METHODS: The study period was 60 days in two followed by three ORs during surgical Block Time (7:30 am until 3:00 pm). Patients were admitted the day before surgery and were thus available and did not have surgery that day unless there was a time reduction. Facilities were already constructed. Number of cases, Nonsurgical Time (Skin Suture Finish until next Procedure Start Time), Turnover Time, and Anesthesia Control Time plus Turnover Time were studied. In addition, economic benefit was calculated. RESULTS: Three hundred thirty-five cases were studied. Using OI, the time of care of regularly scheduled cases was shortened, and the number of cases performed within OR Block Time increased (151 to 184 cases; P < 0.05). Nonsurgical Time (in h:min) decreased (1:08 +/- 0:26 to 0:57 +/- 0:18; P < 0.001), Turnover Time decreased (0:38 +/- 0:24 to 0:25 +/- 0:15; P < 0.05), and Anesthesia Control Time plus Turnover Time decreased (0:43 +/- 0:23 to 0:28 +/- 0:18; P < 0.001). Subgroup analysis showed a significant benefit of OI only in three ORs. In three ORs, economic benefit can be gained at a case mix index greater than 0.3 besides additional costs. CONCLUSIONS: Overlapping induction increased productivity and profit despite the expense of additional staff. Subgroup analysis emphasizes the importance of the number of ORs involved in OI.

Anesthesia↗