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Biomedical subjects

W Schregel

Publications and source records attributed to W Schregel.

At least 19 recordsLinked to original sources
PubMed2003

Cerebral vascular reactivity response to anaesthetic induction with propofol in patients with intracranial space-occupying lesions and vascular malformations.

BACKGROUND AND OBJECTIVE: In clinical trials, autoregulation and carbon dioxide reactivity are preserved during propofol anaesthesia. Paradoxical increases of blood flow velocity during induction of anaesthesia could be demonstrated in patients with brain tumours. This study evaluates the effects of propofol on cerebral blood flow velocity in patients undergoing surgery for brain tumours and vascular malformations. METHODS: Changes in cerebral blood flow velocity after the administration of propofol were assessed using bilateral 2 MHz transcranial Doppler probes in 47 patients undergoing surgery for brain tumours and in 22 patients undergoing surgery for aneurysms and angiomas. RESULTS: Flow reduction after propofol was slightly less pronounced on the side of the tumour; in patients with cerebrovascular lesions, no difference between the two sides was detectable. After the administration of propofol a flow increase was present on the side of the tumour in 2 patients. In 3 patients with angiomas, the flow decrease after the administration of propofol was less pronounced on the side of the angioma. Neither observation gave statistical proof of abnormality. CONCLUSIONS: The flow changes after propofol may give a hint of cerebrovascular reactivity. Further investigations should focus on combined measurements of cerebral autoregulation and carbon dioxide reactivity and should focus on patients with impaired consciousness to test for reliability.

Adolescent↗
PubMed2002

[Detection of air embolism by a re-usable Doppler probe integrated in a central venous line--application in-vivo].

PROBLEM: Air embolism frequently occurs under neurosurgical operations performed in the sitting position. Recently we reported the idea of inserting a re-usable doppler probe into a blind-ending lumen of a central venous catheter (Schregel-Volk-Catheter, SVC). In vitro testing in a circulation model showed a high sensitivity: air bubbles as small as 0.5 microliter were reliably detected at a distance up to 4 cm from the tip of the SVC. METHOD: After approval by the local ethics committee pigs were anaesthetised and a cardiopulmonary bypass was connected. During the bypass period a 12 F SVC (Medex Medical, Germany) with one blind-ending lumen was positioned into the proximal vena cava cranialis or vena cava caudalis. An 8 MHz doppler probe (MTB Basler, Suisse) was introduced into the SVC and connected with the doppler device Multi-Dop T (DWL, Germany). Well defined air bubbles (3-6 microliter) were generated by a bubble generator and injected into the right femoral vein or the left vena jugularis interna. RESULTS: All bubbles were reliably detected by the re-usable doppler probe. Embolic events can be documented, counted and quantified by the Multi-Dop T. CONCLUSION: Using SVC's with a blind-ending lumen could improve and simplify the detection of air embolism. We see several advantages (e.g. sensitivity, costs) compared with established methods (precordial doppler, TEE) for detection of air embolism.

Animals↗
PubMed2001

[Detection of air embolism by a re-usable doppler probe integrated in a central venous line].

PROBLEM: Air embolisms frequently occur during neurosurgical operations. For detection of air embolisms, a re-usable doppler probe, integrated in a central venous line, is described. In an in-vitro test series the measuring sector as well as the function of a 8 MHz doppler probe are presented. METHOD: The 8 MHz doppler probe is a 1.1 mm diameter cable, into the distal end of which a cylindrical doppler crystal from lead-circonate-titanate (PZT5) of 2 x 1.7 mm is integrated and connected with a doppler unit. The detection of micro bubbles with a volume of 0.4-5 microliters was effected in still liquid for simple measuring of the spatial characteristics of the probe as well as in flowing liquid for simulation of a blood circulation system. RESULTS: The doppler probe detected qualitatively and reproducibly all gas bubbles offered up to 4 cm around the tip of the probe. CONCLUSION: A reliable detection of micro-bubbles in this test model is possible by means of a 8 Mhz doppler probe. Further animal and clinical studies are planned.

Catheterization, Central Venous↗
PubMed2001

[Central venous cannulation - always with ultrasound support?].

Central Venous Cannulation - Always with Ultrasound Support?.Ultrasound guided puncture (UGP) improves success and complication rates of central venous cannulation. By some authors UGP with imaging devices are strongly recommended for all cannulations of subclavian or internal jugular veins. In order to review the current literature a computer based abstract search in Medline was performed for the period from January 1972 to May 2000 limited by the key words "catheterization, central venous catheter, internal jugular vein, subclavian vein, axillary vein, femoral vein, ultrasound, ultrasonography, Site-Rite und Smart Needle". UGP of the internal jugular vein was recommended in 29 prospective randomized studies, 21 prospective and three retrospective studies as well as in several clinical reports. UGP of the subclavian vein was supported by only 4 studies, whereas two studies did not show any improvement of puncture results with UGP. Due to the visualisation of the vessel and the cannula imaging techniques represent the "gold standard". However, with conventional Doppler devices nearly the same success rates can be obtained. It does not seem to be justified to perform every central venous cannulation with Doppler or ultrasound support. Each anaesthetist and intensive care physician should be able to perform central venous cannulation without a Doppler or ultrasound device. However, in cases of abnormal anatomy UGP can be helpful to prevent complications. Especially children, patients with coagulation disorders and physicians with limited experience in central venous cannulation can benefit from UGP.

Jugular Veins↗
PubMed2000

Dynamic cerebral autoregulation in patients undergoing surgery for intracranial tumors.

OBJECTIVE: Alterations of cerebral perfusion in brain parenchyma adjacent to tumors have been reported in the literature. The aim of this study was to test cerebral autoregulation in patients scheduled for tumor resection. METHODS: Dynamic cerebral autoregulation was evaluated perioperatively using bilateral transcranial Doppler sonography and the thigh cuff method to alter arterial blood pressure in 50 patients (26 females and 24 males) with a mean age of 49.8 years (range 15-73 years). The alterations of cerebral autoregulation were correlated to size, location and histology of the tumor and the presence of accompanying diseases. RESULTS: Mean cerebral autoregulation was normal before the induction of anesthesia, after intubation under normoventilation, after intubation under hyperventilation and after surgery on intensive care unit. Location, size or histological classification of the lesion was without influence on autoregulation. The patients with accompanying diseases, such as diabetes mellitus and/or hypertension had significantly lower autoregulation values prior to surgery and a significantly lower increase after hyperventilation. CONCLUSION: Cerebral autoregulation is preserved in patients with intracranial tumors regardless of tumor size, if the patient's clinical status prior to surgery is good. The influence of accompanying diseases was demonstrable and should be considered in the perioperative patients management.

Adolescent↗
PubMed1999

[Starch aspiration].

Starch is a white, neutral smelling, insoluble and harmless powder. The case of a 24-year old worker with a pronounced bronchospasm and arterial hypoxaemia after a collapse and aspiration during working in a silo filled with corn starch will be reported. Medication consisted mainly in mucolytics. Intensive airway clearing consisted of repeated bronchoscopies, bedding, tapotement and vibration massage. The patient has made a complete recovery in 3 days.

Accidents, Occupational↗
PubMed1999

[Horner's syndrome following lumbar epidural anaesthesia--subdural block?].

A 28 year old primipara (37th gestational week) was scheduled to undergo delivery by caesarean section under epidural anaesthesia. An epidural catheter was easily inserted in the L3/L4 interspace. After a negative aspiration test 5 ml of bupivacaine 0.25% plus adrenaline 1:200,000 were injected and five minutes later 2 x 5 ml of bupivacaine 0.5% plus fentanyl 0.005 mg/ml were given. Ten minutes after the test dose the patient reported warmth and paraesthesia in the right leg and pelvis and numbness in the right periorbital region. The catheter was drawn back 1.5 centimeters and the operation could be performed under regional anaesthesia with supplemental doses of bupivacaine. Sensory level at the end of the operation was Th 4 which decreased continuously in the following two hours. Ocular symptoms (miosis, ptosis, right-sided numbness) as well as numbness in the right hand and leg persisted four hours longer. The most probable explanation for this peripheral Horner's syndrome is a subdural blockade caused by the first bupivacaine doses. The only known prophylaxis is a fractioned epidural injection of local anaesthetics.

Adult↗
PubMed1998

[Prevention of intraoperative hypothermia in children].

UNLABELLED: Children are very sensible to the occurrence of intraoperative hypothermia (HT) (core temperature < or = 36.0 degrees C) during general anaesthesia because their regulation capacity is less effective than in adults and due to a large skin-surface area compared with their body mass. We compared the efficacy of different heating devices to prevent HT in children during surgery. METHODS: With approval of the local ethics committee 50 children between one and seven years, scheduled for peripheral surgery lasting at least 2 hours were included in this study. Anaesthesia was standardized in all patients. Patients were randomly divided into 5 groups. In group 1, in addition to the usual cotton blankets, room temperature was elevated to 27-28 degrees C. In group 2, room temperature was maintained at 27-28 degrees C, and the patients were additionally wrapped into an aluminum blanket. In group 3, elevated room temperature was combined with a convective heating blanket. Patients in group 4 were warmed with an aluminum blanket, while the room temperature was maintained at 22 degrees C. In group 5, room temperature was maintained at 22 degrees C and patients were warmed with a convective heating device (Tab. 1). Room and core body temperature (tympanon membrane) were continuously measured. ANOVA and Fisher's exact Test (significance level: p < 0.05) were performed for the statistical analysis of the results. RESULTS: The demographic data of all 5 groups, the infused fluid volume and the anaesthetic technique were similar. There were no significant differences concerning age, height and weight of the pediatric patients (Tab. 2). The core temperature decreased by -1.7 degrees C in group 1. In group 4 core temperature decreased by -1.6 degrees C. Using a convective warming system in normal ambient temperature (group 5) core temperature increased by 0.2 degree C and was as effective in the prevention of HT as group 2. A significant increase in core temperature occurred in group 3 +0.7 degree C (Tab. 3 and Fig. 1). DISCUSSION: OR temperature seems to be a critical factor influencing heat loss. Increasing OR temperature and covering with cotton sheets was not effective in preventing the heat loss. Increasing room temperature in combination with aluminum sheets is one alternative to prevent HT. Our study shows that the use of a convective warming device prevents HT during a 2-hour surgery in young children even at a OR temperature of about 22 degrees C. In conclusion, in pediatric patients the use of a convective heating system proved to be an effective alternative to room heating.

Body Temperature↗
PubMed1998

[Delayed lumbar epidural hematoma. Discussion of the risk factors: hypertension, anticoagulation and spinal anesthesia].

This case report deals with the very rare complication of an intraspinal haematoma: a 70 year old male underwent anticoagulation because of supraventricular dysrhythmias followed by two transient ischaemic attacks. He accidentally received an intramuscular injection for tetanus prophylaxis and developed a deep intramuscular haematoma, which was operated upon, after normalisation of coagulation parameters, under spinal anaesthesia. No primary complication was noted. Heparin therapy was started perioperatively, on the day of the operation. Sixteen days postoperatively, the patient resumed oral anticoagulation; 3 months later he developed a progressive cauda-equina-syndrome due to an epidural haematoma at the level of L2 to L4. This could be diagnosed by magnetic resonance imaging, but not by computed tomography. Acute surgical decompression was performed. The haematoma showed various ages as suspected by the intraoperative morphology and proven by histological examination. The neurological findings improved, and 6 months after rehabilitation only slight neurological deficits remained. Hypertension, anticoagulants, and spinal anaesthesia are discussed as risk factors for this complication.

Aged↗
PubMed1997

[Not Available].

Explore the source record for details and available documents.

Comment↗
PubMed1996

[Fatal outcome of a cervical nerve block].

A patient with brachialgia was admitted to a surgical clinic and a cervical nerve block was performed under fluoroscopic guidance. Acute severe cervical pain prevented completion of the procedure. On the following day the patient developed incomplete paralysis of both legs and arms and was transferred to a neurosurgical department for further diagnosis and therapy. The CT scan showed a space-occupying cervical intraspinal haematoma, which was removed immediately as far as possible by a dorsal approach. Postoperatively little improvement of neurologic function was noticed, and 11 days after the event the patient died from a massive pulmonary embolism despite intense resuscitation efforts.

English Abstract↗
PubMed1995

[Transcranial Doppler ultrasound: effects of intravenous anesthetics in neurosurgical patients].

AIM: Although adverse effects on cerebral blood flow have been reported, intravenous anaesthetic and sedative agents are often used in neurosurgical patients. Monitoring of these effects by transcranial Doppler sonography remains a questionable procedure as long as the cross-sectional area of the insonated basal cerebral arteries is unknown. This study should evaluate the effects of thiopental, propofol, midazolam and alfentanil on flow velocities and "vessel cross-sectional area" (proportional to the reflected Doppler signal power) measured by transcranial Doppler sonography. METHOD: 19 patients with severe cerebral lesions (Glasgow Coma Scale < 6) were investigated. They were hyperventilated and sedated with fentanyl and flunitrazepam. The Doppler probe was fixed to the temporal bone and focussed to the middle cerebral artery of the more severely lesioned side. Baseline values of flow velocities and vascular cross-sectional area were measured. If routine nursing procedures required a deeper degree of sedation, either thiopental 2.5 mg/kg, propofol 1 mg/kg, midazolam 0.075 mg/kg or alfentanil 0.025 mg/kg were injected intravenously over 30 s. Further measurements were made 60, 120 and 300 s after start of the injection. Mean +/- SD were calculated, statistical evaluation was performed by analysis of variance and paired t-tests using the Bonferroni correction (p < 0.05). RESULTS: The injected agents induced significant decreases of the mean value of flow velocities; the "vessel cross-sectional area" remained unaltered. In some patients paradoxical increases of v were observed. CONCLUSION: The results indicate that intravenous anaesthetic agents are not likely to influence the cross-sectional area of the major basal cerebral arteries. Therefore TCD seems to be a valid tool to monitor the effects of these agents on the cerebral circulation of neurosurgical patients. This is probably of prognostic and therapeutic value.

Adolescent↗