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Biomedical subjects

M Zimpfer

Publications and source records attributed to M Zimpfer.

At least 19 recordsLinked to original sources
PubMed2006

Antithrombin deficiency and its relationship to severe burns.

Antithrombin (AT) is an important endogenous anticoagulant and exhibits marked anti-inflammatory properties. To evaluate the incidence of AT deficiency in severe burn and its correlation to the variables of the abbreviated burn severity index (ABSI), length of hospital stay (LOS) and mortality we collected data on the substitution of human plasma-derived AT concentrate in 201 consecutive patients suffering from severe burn. One hundred and eight patients (54%) developed AT deficiency during their hospitalisation and, according to our institutional practice, received substitution therapy by continuous infusion to maintain physiological plasma activity (70-120%). The mean administered dose served as a measure of AT deficiency. The percentage of patients in an AT deficient state was highest within the first 5 days after injury. It was 26% on day 1 and between 38% and 41% on days 2-5 and thereafter decreased constantly over time. A multiple regression analysis between the dependent variable mean administered dose of AT concentrate and the independent variables age, total body surface area burned (TBSA), gender, inhalation injury (INHAL), full thickness burn (FTB), LOS and mortality was performed. Age, gender and FTB showed no significant influence on the development of AT deficiency. Increasing TBSA and INHAL clearly increase the risk of developing AT deficiency (p-values 0.0001 and 0.037). The analysis also identified AT deficiency as an independent predictor of LOS and mortality (p-values 0.036 and 0.003). Development of AT deficiency is a frequent event after burn with significant correlation to TBSA and INHAL, increased mortality rates and longer hospital stays.

Anticoagulants↗
PubMed2005

Effect of newer anaesthetics on duration of stay in postanaesthesia care unit in patients undergoing major abdominal surgery.

Newer anaesthetic agents, such as remifentanil and sevoflurane, are more expensive than conventional anaesthetics, such as isoflurane and fentanyl. However, newer anaesthetics might outweigh their higher acquisition costs by reducing length of stay in the postanaesthesia care unit and thereby reducing personnel costs. We retrospectively investigated the influence of newer anaesthetics on time to eligibility for discharge from the postanaesthesia care unit in consecutive patients undergoing major abdominal surgery. Using a chart review, patients undergoing major abdominal surgery with three different anaesthetic regimens (isoflurane/fentanyl (n = 80), sevofluranelfentanyl (n = 40), and sevoflurane/remifentanil (n = 42)) were compared regarding duration of anaesthesia, surgery, time till extubation, and time to eligibility for discharge from the postanaesthesia care unit. Extubation times were shorter in patients in the sevoflurane/fentanyl and the sevoflurane/remifentanil groups compared to patients in the isoflurane/fentanyl group. Time to eligibility to discharge from the postanaesthesia care unit was similar in isoflurane/fentanyl and sevoflurane/fentanyl group. In the sevoflurane/fentanyl group, time to eligibility for discharge from the unit showed a tendency to be increased (P = 0.08), however these patients were significantly older compared to the other groups. Sevoflurane and remifentanil did not appear to reduce time to eligibility to discharge from the postanaesthesia care unit in our patients undergoing major abdominal surgery compared to isoflurane and fentanyl. This study highlighted the necessity for carefully planned transition from remifentanil to other longer-acting analgesia in our patients.

Abdomen↗
PubMed2004

Clonidine as an adjuvant to local anaesthetic axillary brachial plexus block: a randomized, controlled study.

BACKGROUND: We compared the effects of clonidine added to levobupivacaine and bupivacaine on axillary brachial plexus block as well as the effectiveness of levobupivacaine alone compared with bupivacaine alone. METHODS: In this prospective, randomized, controlled, double-blind trial, four groups of 20 patients each were investigated, using (i) 40 ml of levobupivacaine 0.5% plus 0.150 mg of clonidine, (ii) 40 ml of levobupivacaine 0.5% plus 1 ml of NaCl 0.9%, (iii) 40 ml of bupivacaine 0.5% plus 0.150 mg of clonidine, and (iv) 40 ml of bupivacaine 0.5% plus 1 ml of NaCl 0.9%, respectively. The onset of motor and sensory block and duration of sensory block were recorded. RESULTS: There was no significant difference in duration between groups, but a significantly higher variance (P<0.001) was found in the two groups with clonidine than in the two groups without. CONCLUSIONS: These findings suggest responder and non-responder behaviour is a result of the addition of clonidine.

Adjuvants, Anesthesia↗
PubMed2003

A comparison of propofol and sevoflurane anaesthesia: effects on aortic blood flow velocity and middle cerebral artery blood flow velocity.

We compared systemic (aortic) blood flow and cerebral blood flow velocity in 30 patients randomly allocated to receive either propofol or sevoflurane anaesthesia. Cerebral blood flow velocity (CBFv) was measured in the middle cerebral artery using transcranial Doppler. Systemic blood flow velocity (SBFv) was measured in the aorta using transthoracic Doppler sonography at the level of the aortic valve. Bispectral index (BIS) was used to measure the depth of anaesthesia. Measurements were made in the awake patient and repeated during propofol or sevoflurane anaesthesia, with BIS measurements of 40-50. The effects of SBFv on CBFv were estimated by calculating the cerebral/systemic blood flow velocity-index (CsvI). A CsvI value of 100 indicating a 1 : 1 relationship between CBFv and SBFv. The results demonstrated that propofol anaesthesia produced a significantly greater reduction in CsvI than did sevoflurane anaesthesia [propofol: 60 (19); sevoflurane: 83 (16), p = 0.009, t-test]. This suggests a direct reduction in CBFv independent of SBFv during propofol anaesthesia. The greater reduction of CBFv occurring during propofol anaesthesia may be due to lower cerebral metabolic demand compared with sevoflurane anaesthesia at comparable depths of anaesthesia.

Adult↗
PubMed2003

The effect of graded hypothermia (36 degrees C-32 degrees C) on hemostasis in anesthetized patients without surgical trauma.

UNLABELLED: The isolated effects of hypothermia on hemostasis have not been investigated in healthy humans. We cooled 16 anesthetized patients scheduled for elective intracranial surgery to 32 degrees C body core temperature and assessed prothrombin time (PT), activated partial thromboplastin time, thrombelastogram (TEG), closure time, and platelet count at 36 degrees C, 34 degrees C, and 32 degrees C body core temperature after the induction of anesthesia but before surgical intervention. Activated partial thromboplastin time, hematocrit, and closure time did not change, whereas PT and platelet count decreased during cooling. Platelet count decreased without a decrease in hematocrit; hence, a dilution by administered fluids seemed unlikely. The small decrease of platelet count is probably clinically irrelevant in patients with normal platelet count and function. The small decrease in PT indicates an alteration of the extrinsic pathway of coagulation. TEG measurements showed a delay of clot formation in temperature-adjusted measurements but showed no change if the test temperature was 37 degrees C. This indicates that hypothermia reduces plasmatic coagulation and platelet reactivity. However, the clot strength is not altered by hypothermia. All coagulation variables remained within the normal ranges. Our results may indicate that moderate short-term (4-h) hypothermia has only minor adverse effects in healthy humans. We can make no statement about the effects of hypothermia of longer duration. IMPLICATIONS: This study investigated the isolated effects of hypothermia in healthy anesthetized humans. We found only minor effects of body temperature reduction to 32 degrees C on assessed coagulation variables, indicating only minor effects in otherwise healthy humans.

Adult↗
PubMed2001

Impact of early high caloric duodenal feeding on the oxygen balance of the splanchnic region after severe burn injury.

Early enteral nutrition is recommended in burned patients. Depending on the amount administered, enteral feeding causes an increase of intestinal oxygen-demand. Although early moderate enteral nutrition has been shown to be beneficial, early high calorie enteral nutrition might lead to an imbalance of the O(2)-balance of the gut since intestinal perfusion is decreased after major burns. In 20 severely burned patients during the first 48 h of early high caloric duodenal feeding an assessment of the CO(2)-gap between the arterial and the gastric CO(2), as parameter for the intestinal O(2)-balance, was performed. Time points were prior to starting the enteral nutrition (BASE) subsequently every 30 min after increasing the amount of nutrition administered and from the 11th to the 48th h after beginning of nutrition in intervals of 6 h. In none of the patients was the CO(2)-gap increased during the rapid increase of enteral nutrition. On the contrary the CO(2)-gap decreased significantly. We conclude that high caloric duodenal feeding in the early hypodynamic postburn phase does not have adverse effects on the oxygen balance of the intestine.

Adult↗
PubMed2001

Influence of aortic blood flow velocity on changes of middle cerebral artery blood flow velocity during isoflurane and sevoflurane anaesthesia.

BACKGROUND AND OBJECTIVE: We studied the influence of systemic (aortic) blood flow velocity on changes of cerebral blood flow velocity under isoflurane or sevoflurane anaesthesia. METHODS: Forty patients (age: isoflurane 24-62 years; sevoflurane 24-61 years; ASA I-III) requiring general anaesthesia undergoing routine spinal surgery were randomly assigned to either group. Cerebral blood flow velocity was measured in the middle cerebral artery by transcranial Doppler sonography (depth: 50-60 mm). Systemic blood flow velocity was determined by transthoracic Doppler sonography at the aortic valve. Heart rate, arterial pressure, arterial oxygen saturation and body temperature were monitored. After standardized anaesthesia induction (propofol, remifentanil, vecuronium) sevoflurane or isoflurane were used as single agent anaesthetics. Cerebral blood flow velocity and systemic blood flow velocity were measured in the awake patient (baseline) and repeated 5 min after reaching a steady state of inspiratory and end-expiratory concentrations of 0.75, 1.00, and 1.25 mean alveolar concentrations of either anaesthetic. To calculate the influence of systemic blood flow velocity on cerebral blood flow velocity, we defined the cerebral-systemic blood flow velocity index (CSvI). CSvI of 100% indicates a 1:1 relationship of changes of cerebral blood flow velocity and systemic blood flow velocity. RESULTS: Isoflurane and sevoflurane reduced both cerebral blood flow velocity and systemic blood flow velocity. The CSvI decreased significantly at all three concentrations vs. 100% (isoflurane/sevoflurane: 0.75 MAC: 85 +/- 25%/81 +/- 23%, 1.0 MAC: 79 +/- 19%/74 +/- 16%, 1.25 MAC: 71 +/- 16%/79 +/- 21%; [mean +/- SD] P = 0.0001). CONCLUSIONS: The reduction of the CSvI vs. 100% indicates a direct reduction of cerebral blood flow velocity caused by isoflurane/sevoflurane, independently of systemic blood flow velocity.

Adult↗
PubMed2001

The influence of deliberate hypotension on splanchnic perfusion balance with use of either isoflurane or esmolol and nitroglycerin.

UNLABELLED: Various techniques to induce deliberate hypotension (DH) have different influences on splanchnic perfusion. The aim of our study was to determine whether splanchnic perfusion is clinically impaired during DH by using either isoflurane (ISO) or a combination of esmolol and nitroglycerin (E/N). We randomized 16 patients undergoing elective maxillofacial surgery to receive either ISO (0.7%-1.8%) or E (105 g x kg(-1) x min(-1)) and N (1-6 mg/h) to induce DH. General anesthesia was performed in both groups by IV midazolam 0.07 mg/kg, fentanyl 0.003 mg/kg, propofol 1.5 mg/kg, and vecuronium 0.1 mg/kg followed by a propofol infusion with 6 mg x kg(-1) x h(-1). After the induction of anesthesia, a gastric tonometer (TRIP NGS Catheter) and a radial artery catheter were inserted. Baseline values of gastric intramucosal pH (pHi) were determined 60 min after placement of the catheter and before the induction of DH. The pHi values were calculated every 60 min until DH was discontinued. In both groups, DH was satisfactorily established. None of the pHi values calculated was less than 7.37 in the E/N or 7.41 in the ISO group. Arterial blood lactate levels did not increase in any of the patients. We conclude that neither method of producing DH compromises splanchnic tissue oxygen balance in healthy patients. Furthermore, overall organ perfusion was sufficient in both groups, because none of the patients showed an increase in blood lactate. IMPLICATIONS: Neither the isoflurane nor the esmolol/nitroglycerin method of producing deliberate hypotension compromises splanchnic tissue oxygen balance in healthy patients. Furthermore, overall organ perfusion was sufficient in both groups, because none of the patients showed an increase in blood lactate.

Adrenergic beta-Antagonists↗
PubMed2001

First experience with fiberoptically directed wire-guided endobronchial blockade in severe pulmonary bleeding in an emergency setting.

We report the first use of a new wire-guided endobronchial blocker in a critical respiratory situation caused by localized pulmonary bleeding. During emergency management, it became increasingly difficult to ventilate a multiple-trauma patient with a conventional single-lumen tube because of massive bleeding through the bronchus of the left lower lobe. Using the Arndt endobronchial blocker set (William Cook Europe A/S; Bjaeverskor, Denmark), we were able to prevent the spread of hemorrhaging and achieved effective ventilation and marked improvement in gas exchange. This new device allows the effective blockade of an isolated lobe under direct bronchoscopy to buy time for further intervention.

Bronchoscopy↗
PubMed2000

Superimposed high-frequency jet ventilation for laryngeal and tracheal surgery.

OBJECTIVE: To describe our experience with superimposed high-frequency jet ventilation (SHFJV), which does not require any endotracheal tubes or catheters, for performing laryngeal and tracheal surgery. DESIGN: A case series of 500 patients. SETTING: A university medical center. PATIENTS: Four hundred sixty adult patients and 40 children in a consecutive sample who required laryngeal or tracheal surgery under SHFJV. INTERVENTIONS: The SHFJV uses 2 jet streams with different frequencies simultaneously and is applied using a jet laryngoscope. Ventilation was performed with an air-oxygen mixture, and intravenous agents were used for anesthesia. Arterial blood gas values were analyzed. MAIN OUTCOME MEASURES: Reported values of oxygenation and ventilation during the application of SHFJV and laryngotracheal surgery. RESULTS: In 497 patients, adequate oxygenation with a mean +/- SD PaO2 of 91.8 +/- 22.9 mm Hg and ventilation with a PaCO2 of 29.7 +/- 5.5 mm Hg were achieved using SHFJV. The average duration of the application of ventilation was 27 minutes, and the longest duration was 118 minutes. No complications due to the ventilation technique were observed. Laser surgery was performed in 150 patients. CONCLUSIONS: The use of SHFJV in combination with the jet laryngoscope provides patients with sufficient ventilation during laryngotracheal surgery. Even in patients at high risk because of pulmonary or cardiac disease, this technique can be applied safely. In patients with stenosis, the ventilation is applied from above the stenosis, reducing the risk of barotrauma. The SHFJV can be used for tracheobronchial stent insertion, and laser can be used without any additional protective measures.

Adolescent↗
PubMed2000

Variations in ILMA external diameters: another cause of device failure.

PURPOSE: To report failure of insertion of #5 and #4 intubating laryngeal mask airways (ILMAs) in a patient with a mouth opening of just under 25 mm, and the variances among same-size ILMAs. CLINICAL FEATURES: A 53-yr-old man with obstructive sleep apnea underwent elective ENT surgical repair. His mouth opening was just under 25 mm. Ventilation by mask was easy. Direct laryngoscopy failed after induction of anesthesia and neuromuscular block. Neither a #5 nor a #4 ILMA could be passed between the patient's teeth, despite different twisting maneuvres. A #4 LMA was thus prepared as a conduit for fibreoptic intubation. Placement of the LMA was easy, as was fibreoptic-guided intubation. The LMA was removed over the tracheal tube (TT) to enable ENT surgery, and the further course was uneventful. Manual examination showed that, unlike others of the same type, the failed ILMAs were not sufficiently compressible either to allow insertion in this patient or to the 20 mm reported as the maximal outer dimension of the device. Radiological examination revealed that, at the point of the device where it is intended to be compressible, the silicone layer was thicker in the failed devices than in stock compressible ILMAs, and the end of the steel tube was not so sharply beveled. CONCLUSION: Our inability to insert an ILMA in a patient with an interdental distance of just under 25 mm was because the device was not sufficiently compressible although the manufacturer states the maximal outer dimension to be 20 mm.

Anesthesia↗
PubMed2000

Depressive effect of isoflurane on motor evoked potentials in the Nubian goat.

PURPOSE: To determine the effect of isoflurane on motor evoked potentials (MEP) in a new animal model designed to verify the applicability of MEPs in brachial plexus surgery, and to compare the results with previous reports in other animals. METHODS: In seven goats, anesthesia was induced with 3 mg x kg(-1) ketamine i.v. and maintained with nitrous oxide 40% in oxygen and 2 microg x kg(-1) x hr(-1) fentanyl i.v.. The MEP were performed with two subcutaneous needle electrodes placed over the occiput (cathode) and the nasion (anode), with their plugs connected to the power output of a Digitimer D 180 electrical stimulator, connected to the trigger input of an electromyograph (model 8400, Cadwell Laboratories, Inc., Kennwick, Washington). Activation of the Digitimer caused central stimulation of the motor cortex, evoking baseline compound muscle action potentials (CMAPs) which were recorded from the left triceps muscle. Subsequently, isoflurane 2% was administered together with repeated central stimulation at 30 sec intervals. RESULTS: Onset of I- (indirect) waves increased from median 15,8 msec to median 26,8 msec P = 0,018 (latency increase ranged from: 9 to 11.5 msec), while peak-to-peak amplitudes decreased and subsequently disappeared. D- (direct) waves showed no latency increase, and finally disappeared as well. After disappearance of CMAPs, isoflurane administration was stopped and MEP repeated. The CMAPs reappeared (range: 210-360 sec) and regained initial peak-to-peak amplitudes and latencies. CONCLUSION: These animal studies suggest that isoflurane should not be used during the recording of MEPs.

Action Potentials↗
PubMed2000

Propofol without muscle relaxants for conventional or fiberoptic nasotracheal intubation: a dose-finding study.

UNLABELLED: Endotracheal intubation has been performed during the administration of propofol anesthesia without neuromuscular blockade. In this study, we determined the propofol dose required for conventional nasotracheal or for fiberoptic nasotracheal intubation of all patients. Thirty-two patients undergoing maxillofacial surgery were randomly assigned to the conventional (n = 16) or to the fiberoptic (n = 16) intubation group. In both groups, anesthesia was induced by using IV fentanyl and IV titrated propofol according to clinical need (spontaneous respiration rate, verbal response). An endotracheal tube was placed nasally in the pharynx and the vocal cords visualized by using a fiberscope inserted via the tube. In the conventional group, the larynx was visualized additionally with a laryngoscope blade (Miller). In both groups propofol was titrated until the vocal cords opened. Patients were tracheally intubated, and the propofol dose was recorded. In all patients, the trachea could be intubated without the use of muscle relaxants. Considerable interindividual differences of dose requirements were observed. The amount of propofol required in the conventional group was significantly (P < 0.0001) larger (median +/- SD: 2.74 +/- 1.59 mg/kg; range 1.95-7.07 mg/kg) than in the fiberoptic group (1.37 +/- 0.59 mg/kg; 0.72-2.86 mg/kg). Hemodynamics remained stable in all patients. Postintubational hoarseness occurred in three patients of each group. Fiberoptic nasal intubation without a muscle relaxant can be facilitated with significantly smaller and more predictable dosages of propofol than conventional nasal endotracheal intubation. The possibility of titrating the propofol dose under assisted ventilation until the vocal cords open during fiberoptic nasotracheal intubation and the better predictability of the required dose favors the fiberoptic approach. IMPLICATIONS: In this study, contrary to all preceding studies using predefined doses of propofol and opioids, we determined the minimal required propofol dose in combination with fentanyl for conventional or fiberoptic nasotracheal intubation without muscle relaxants.

Adult↗
PubMed2000

Tromethamine buffer modifies the depressant effect of permissive hypercapnia on myocardial contractility in patients with acute respiratory distress syndrome.

In patients with acute respiratory distress syndrome (ARDS), permissive hypercapnia is a strategy to decrease airway pressures to prevent ventilator-induced lung damage by lowering tidal volumes and tolerating higher arterial carbon dioxide tension. However, in experimental studies hypercapnia impairs myocardial contractility and hemodynamic function. We investigated the effect of short-term permissive hypercapnia on myocardial contractility and hemodynamics in patients with ARDS. We hypothesized that the administration of tromethamine (THAM), a buffer which does not increase carbon dioxide production, would modify these changes. In 12 patients with ARDS, permissive hypercapnia was implemented for 2 h with a target Pa(CO(2))of 80 mm Hg. Patients were randomized to have respiratory acidosis corrected by THAM (pH-corrected group), or not corrected (pH-uncorrected group). Hemodynamic responses were measured, and transesophageal echocardiography (TEE) was used to determine myocardial contractility. Permissive hypercapnia resulted in significant decreases in systemic vascular resistance (SVR) and increases in cardiac output (Q). Myocardial contractility decreased in both groups but significantly less in the pH-corrected group (approximately 10%) than in the pH-uncorrected group (approximately 18%, p < 0.05). Mean arterial pressure decreased and mean pulmonary arterial pressure increased significantly only in the pH-uncorrected group. All values returned to baseline conditions 1 h after permissive hypercapnia was terminated. Our study demonstrates a reversible depression of myocardial contractility and hemodynamic alterations during rapid permissive hypercapnia which were attenuated by buffering with THAM. This may have applicability to the clinical strategy of permissive hypercapnia and allow the benefit of decreased airway pressures to be realized while minimizing the adverse hemodynamic effects of hypercapnic acidosis.

Acid-Base Equilibrium↗
PubMed2000

[Abdominal vascular surgery emergencies: abdominal aortic aneurysm, acute mesenteric ischemia--indications, technique, results].

Ruptured infrarenal aortic aneurysms and mesenteric ischemia are abdominal emergency situations, which should be treated by vascular surgeons. Modern means of patient transport and specialized emergency centers make it possible to bring patients suspect of having a ruptured aneurysm or a mesenteric ischemia to experienced clinics. Indication for surgery in case of symptomatic or ruptured aortic aneurysms is doubtless absolute. If there is suspicion for a ruptured aneurysm, emergency operation is indicated. In patients having undergone emergency surgery for a ruptured aneurysm of the infrarenal aorta, hospital mortality was 41%. The initial indication for surgery for patients with mesenteric ischemia usually is the "acute abdomen". Mostly only the patient's history reveals the suspicion for this disease. There are no valid radiologic examinations for proving or ruling out mesenteric ischemia. Most of our patients had arterial embolism (64%) as a source of mesenteric ischemia, followed by arterial thrombosis (28%), venous thrombosis (3%) and non-occlusive ischemia (5%). Monitoring of levels of serum lactate can be an additional tool for decision making, if a second look operation is discussed. The key for surgical success with these critically ill patients is shortening of the interval between the first symptoms of the patient and the start of surgical therapy.

Aged↗