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Biomedical subjects

B Bachmann-Mennenga

Publications and source records attributed to B Bachmann-Mennenga.

9 recordsLinked to original sources
PubMed1996

Volume replacement with gelatin or hydroxyethylstarch solutions does not impair somatosensory evoked potential monitoring: a haemodilution study in conscious volunteers.

The influence of haemodilution with colloids on somatosensory evoked potentials in non-premedicated volunteers is reported. In seven volunteers (randomized crossover design), blood (20 mL kg-1 within 30 min) was removed and simultaneously replaced by gelatin 3% or hydroxyethylstarch 6%. After 30 min, blood was retransfused within 30 min. Median and posterior tibial nerve somatosensory evoked potentials were recorded from the cortex, second cervical vertebra, Erb's point and 1st lumbar vertebra, respectively. One volunteer experienced a severe allergic reaction to gelatin, therefore only six gelatin trials were evaluated. Haemodilution decreased the haematocrit from 39.8 +/- 1.6% (mean +/- SD) to 31.1 +/- 2.0% (gelatin) and from 40.7 +/- 1.7% to 29.8 +/- 1.5 % (hydroxyethylstarch), respectively. Retransfusion increased haematocrit to 34.4 +/- 0.9% (gelatin) and to 34.2 +/- 1.3% (hydroxyethylstarch). Neither haemodilution with gelatin nor haemodilution with hydroxyethylstarch or retransfusion influenced evoked potentials. In conclusion, the treatment of blood loss up to 30% of estimated blood volume with gelatin or hydroxyethylstarch will not affect somatosensory evoked potential monitoring provided normovolaemic conditions are maintained.

Adult↗
PubMed1996

Isovolaemic haemodilution with hydroxyethylstarch has no effect on somatosensory evoked potentials in healthy volunteers.

BACKGROUND: An animal study in anaesthetized baboons demonstrated that somatosensory evoked potentials (SSEP) can be affected by extreme haemodilution. This might lead to misinterpretation and reduce the value of intraoperative SSEP monitoring when colloids are administered. In the present study, the effect of haemodilution (HD) and subsequent retransfusion of autologous blood on SSEP was determined in healthy non-premedicated volunteers. METHOD: Acute isovolaemic HD served as a model for blood loss immediately replaced with colloids. In 12 volunteers, 20 ml/kg.bw blood was withdrawn within 30 minutes and simultaneously multaneously replaced with 6% hydroxyethylstarch (HES). 30 minutes later, the autologous blood was retransfused within 30 minutes. Recording sites and parameters were: 1. Median nerve SSEP: cortical, cervical (C2), Erb's point; 2. Posterior tibial nerve SSEP: cortical, cervical (C2), lumbar (L1). In addition to SSEP latency and amplitude, median and tibial nerve central conduction times, spinal conduction time and nerve conduction velocity were determined. Serial SSEP measurements were made before, during and after HD and retransfusion every 15 minutes. RESULTS: HD consisting of a withdrawal volume of 1550 +/- 155 ml (mean +/- SD) induced a decrease in haematocrit from 42.0 +/- 3.1% to 29.6 +/- 1.6% (P < 0.001). Following retransfusion, haematocrit increased to 35.0 +/- 2.1% (P < 0.001). Neither HD nor retransfusion influenced SSEP parameters. CONCLUSION: We conclude from our data that the therapy of blood loss up to 30% of estimated blood volume with HES does not affect SSEP monitoring as long as normovolaemia is maintained.

Adult↗
PubMed1995

[Does controlled hypotension with nitroprusside affect platelet function?].

Induced hypotension is an accepted technique to reduce intraoperative blood loss and thereby ensures satisfactory operating conditions, especially in microscopic interventions. Sodium nitroprusside (NP), which is often used for induced hypotension, was reported to inhibit platelet aggregation in vitro. Impairment of platelet function implies a higher bleeding risk, which would make the use of NP for induced hypotension questionable. METHODS. With the approval of the local ethics committee, 30 patients scheduled for nasal septum operations were included in this randomised study. For induction of anaesthesia 2 mg vecuronium, 0.1 mg fentanyl, 0.2 mg/kg etomidate, and 1 mg/kg succinylcholine were used. After tracheal intubation the patients inhaled 1.0-1.5 vol.% isoflurane in a gas mixture containing 66% nitrous oxide in oxygen. Fifteen patients received an i.v. infusion of NP for 60 min. The concentrations chosen produced a decrease of mean arterial blood pressure to 50 mm Hg. Blood samples were taken before induction of anaesthesia; after induction of anaesthesia but before beginning of the operation; and 60 min after the beginning of the operation. This time-point coincided with the end of NP administration in the study group. The last blood sample was drawn the morning after the operation. Platelet function was determined in platelet-rich plasma by a turbidometric method after adding 22 mumol/l epinephrine to induce aggregation. The spontaneous aggregation was measured in whole blood using impedance aggregometry. Data within one group were analysed using analysis of variance. Student's t-test for unpaired values served to compare data between the two groups. RESULTS. Biometric data in the two groups were comparable. The blood loss in the control group [265 (190-410) ml] significantly exceeded (P < 0.05) that in the hypotensive group [125 (75-210) ml]. No significant changes in platelet function were found throughout the study period in the patients treated with NP. In the control patients the epinephrine-induced aggregation increased significantly from 53.1 +/- 5.3% before anaesthesia to 72.1 +/- 3.3% the morning after the intervention. The spontaneous aggregation showed a significant increase from 0.718 +/- 0.338 Ohm/h before anaesthesia to 2.164 +/- 0.442 Ohm/h 60 min after the beginning of the operation. The value on the 1st postoperative day (2.266 +/- 0.448 Ohm/h) was also significantly higher than the basal value. CONCLUSIONS. In contradiction to in vitro studies using high concentrations of NP, we could not find a decrease in platelet aggregation due to hypotensive anaesthesia with this drug in vivo. In the control group a significant increase in platelet aggregation was observed, which was probably counteracted in the hypotensive patients by the interaction of NP with cyclic guanosine monophosphate (c-GMP). NP augments the intracellular concentration of c-GMP, which is known to decrease platelet aggregation.

Adolescent↗
PubMed1995

Increase of interleukin-6 plasma concentrations and HLA-DR positive T-lymphocytes after hypotensive anaesthesia with sodium nitroprusside.

Interleukin-6 (IL-6), a cytokine involved in the pathogenesis of sepsis and septic shock, and lymphocyte subpopulations were measured in blood circulation of patients receiving sodium nitroprusside (SNP) for induction of hypotension. The aim of this study was to evaluate whether this procedure influences distribution of lymphocyte subsets and IL-6 response. 30 patients of ASA physical status I and II scheduled for nose-septum correction were randomly assigned to the SNP- or control group (without SNP). Patients were anaesthetized with fentanyl, etomidate and isoflurane in 66% nitrous oxide. SNP was administered continuously during 60 min and mean arterial blood pressure was reduced to 50 mmHg. Before and after induction of anaesthesia, 60 min after the beginning of the operation (end of SNP-infusion) and on the first postoperative day, IL-6 plasma concentrations were determined by ELISA. The percentages of B-, T-lymphocytes, T-helper, T-suppressor cells and HLA-DR positive (activated) T-lymphocytes were examined by direct immunofluorescence using monoclonal antibodies. On the first day after surgery IL-6 plasma concentrations were significantly elevated in the SNP-group compared to preoperative values. In this group the values were higher than in control patients [30.5 (10.9-47.5) pg/ml vs. 17.4 (8.5-21.5) pg/ml]. The percentage of HLA-DR positive T-cells was 25.8 +/- 4.9% in the patients with SNP on the first postoperative day; it was significantly higher than in control patients [16.5 +/- 3.7%]. We conclude that SNP-administration increases percentage of activated T-cells and IL-6 secretion.

Adolescent↗
PubMed1993

Intercostal nerve block, interpleural analgesia, thoracic epidural block or systemic opioid application for pain relief after thoracotomy?

The purpose of this study was to investigate the effect of different pain-relief methods (regional and systemic) following thoracotomies on the cardiovascular system, pulmonary gas exchange, various endocrine parameters and subjective perception. A further aspect was to evaluate the benefits of interpleural analgesia as a new regional technique against already established regional techniques, such as intercostal nerve block and thoracic epidural block. All postoperative pain methods led to a significant time-dependent reduction of the adrenaline concentrations in plasma while the noradrenaline concentrations did not change significantly. There were no statistical differences in catecholamine concentrations among the different study groups, although the mean concentrations of adrenaline in patients having a thoracic epidural block for pain relief were lower in comparison to the findings in other groups. The plasma concentrations of the "stress metabolites", such as glucose, free fatty acids and lactate, as well as the haemodynamic (mean arterial pressure, heart rate) and pulmonary parameters (blood gas analyses), showed no significant differences among groups. In contrast to the other pain-relieving methods, interpleural analgesia did not lead to sufficient pain relief in that 7 out of 10 patients needed supplementary systemic opioid therapy. Therefore, interpleural analgesia for pain relief following thoracotomies cannot be recommended.

Adrenocorticotropic Hormone↗
PubMed1991

[Ultrafiltration as a fast and simple method for determination of free and protein bound prilocaine concentration. Clinical study following high-dose plexus anesthesia].

Ultrafiltration as a Fast and Simple Method to Separate Free and Protein Bound Concentrations of Local Anesthetics/Pharmacokinetic studies following high-dose anesthesia of the axillary plexus. As many other drugs amide-type local anesthetics are protein bound in plasma. The extent of binding varies between local anesthetics. The free, non protein-bound fraction of these drugs is mainly responsible for cardiovascular and central-nervous side effects. If high doses are necessary for regional anesthetic procedures it seems reasonable to determine the pharmacological active, non protein-bound fraction in addition to the total concentration of the local anesthetic drug. Analyses of protein binding was performed using an ultrafiltration method which is discussed in this paper. Total (HPLC) and unbound plasma levels (combination of ultrafiltration and HPLC) of the local anesthetic drug in central venous blood were studied in 20 healthy orthopedic patients, undergoing plastic surgery of the upper limb (elbow, forearm, hand), over a time period of 90 min, when performing axillary plexus block with 30 ml prilocaine (CAS 721-50-6) 2% (= 600 mg). Separation of the local anesthetic fractions was achieved using the ultrafiltration system MPS-1, equipped with a YMT-membrane. These membranes have a narrow pore size retaining molecules larger than 30000 Dalton. Ultrafiltration was accomplished by subjecting 1.2 ml of plasma to centrifugation at 2000 x g for 60 min at 30 degrees C using a clinical centrifuge equipped with a 35 degree angle head rotor. The plasma samples were adjusted to physiological pH (7.40) with a sodium-potassium-phosphate buffer. The tightness of the used membrane was controlled by a micromethod for protein estimation (sensitivity 10 micrograms/ml).(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Proteins↗
PubMed1989

[Hyperthermic reaction in the perioperative phase in 2 children with acute lymphoblastic leukemia of B-cell type].

Acute lymphatic leukemia (ALL) represents one of the most frequent malignancies in childhood. Central venous access ports or partly implanted silicone catheters are usually placed for high-dose chemotherapy in these children. We report two patients aged 7 and 3 years with acute lymphoblastic beta-cell leukemia (B-ALL), a less common subtype of ALL, which presented with hyperthermia (38.4 degrees C and 39 degrees C) during anesthesia with isoflurane for implantation of a central venous catheter. The hyperthermic reactions were accompanied by an increase in expired CO2 and acidosis as well as moderate elevation of heart rate and blood pressure. As in both patients the history and preoperative findings did not reveal signs of infection or other causes of fever, the observed alterations were interpreted as symptoms of malignant hyperthermia triggered either by succinylcholine or isoflurane, which were used in both children. In addition, the hyperthermia responded to administration of dantrolene sodium according to dose recommendations for treatment of malignant hyperthermia. In one of the patients, withdrawal of dantrolene during the initial postoperative hours was followed by a recurrent increase in body temperature, which once again could be suppressed by additional dantrolene infusion. According to the literature, malignant hyperthermia has occasionally been described in children with malignancies such as leukemia or Burkitt's lymphoma. Our observations indicate that children with B-ALL may be especially susceptible to malignant hyperthermia. Close monitoring of body temperature and expiratory CO2 are therefore indicated in these children, and dantrolene therapy should be started immediately in case of increased temperature during anesthesia.

Anesthesia, Inhalation↗
PubMed1987

[Opinion of mothers on continuous peridural obstetrical anesthesia].

The general opinion on epidural anesthesia in obstetrics may be adversely affected by recent public controversies about the mother's situation during childbirth in hospital, which nowadays is often considered to be a highly technological, impersonal, or "unnatural" procedure. This assumption led us to conduct an inquiry on maternal assessment of obstetric epidural anesthesia and its relation to the clinical and social history. The study included 113 parturients, who received epidural anesthesia (on-demand epidural injections of bupivacaine 0.25%) for vaginal delivery. Mothers were asked to answer certain questions about this regimen (e.g. analgetic efficacy; difficulties in deciding on this method; recommendations to other parturients; opinion of the role of epidural anesthesia in obstetrics; choice of analgesic regimen for future childbirth) 1 day after delivery and 2 months later. Additional social and historical factors (e.g. education; profession; family status; preceding pregnancy, childbirth or abortion; complications during pregnancy or childbirth; duration of parturition) were used to reveal relevant statistical correlations. Sixty-five percent of the patients considered pain relief by epidural anesthesia as "good" or even "very good" during the first inquiry immediately after childbirth. Women who had undergone prior interruptions of pregnancy were less satisfied, probably because of their rather ambiguous attitude towards motherhood. With regard to the choice of analgesic regimen for future childbirth (50% of the patients had made a definite decision to have epidural anesthesia under this condition), those women were especially reserved who had suffered from complications during pregnancy and disapproved of it in the future.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, Epidural↗