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Biomedical subjects

F W Ahnefeld

Publications and source records attributed to F W Ahnefeld.

At least 109 records · Page 6Linked to original sources
PubMed1985

[Aortofemoral bifurcation bypass--effect of anesthesia procedure (NLA, thoracic continuous catheter peridural anesthesia) on circulation, respiration and metabolism. Hemodynamic changes caused by peridural anesthesia and anesthesia induction].

UNLABELLED: In 50 patients scheduled for infrarenal aortic bypass surgery the cardiovascular effects of two anaesthetic regimes were investigated prior to surgery. A Swan-Ganz-catheter was used for haemodynamic measurements. These patients, having been randomized into two groups, were optimally volume loaded (PCWP 10 mmHg) before anaesthesia. In 24 patients a thoracic epidural was induced with 12-15 ml 0.25% plain bupivacaine. When segmental anaesthesia had extended from T4/5 to L1/2 general anaesthesia was additionally applied (flunitrazepam 1.5-2 mg, pancuronium bromide 0.1 mg/kg). In 26 patients neuroleptanaesthesia was induced (droperidol 0.1-0.2 mg/kg, fentanyl 0.01 mg/kg, pancuronium bromide 0.1 mg/kg, and thiopentone 100-150 mg. Haemodynamic measurements were made before injection into the epidural catheter, after complete spread of anaesthesia, before commencing general anaesthesia and 10-15 min thereafter. RESULTS: Neither of the two procedures were associated with severe haemodynamic alterations. In the epidural group HR fell slightly during latency of complete spread and increased to the same extend following general anaesthesia. The epidural caused MAP (104 to 88 mmHg), mean PAP (20 to 14 mmHg), PCWP (10 to 7.5 mmHg), and RAP (4.5 to 2.5 mmHg) to decrease moderately but no further changes were effected by the subsequent general anaesthesia. SVR and PVR were not influenced by either epidural or by general anaesthesia. CI (3.6 to 3.41 . min-1 . m-2), LVSWI (67 to 52 p . m-1), and cardiac minute work index (55 to 40 J . min-1 . m-2) decreased during latency of complete spread but were no further influenced by general anaesthesia. The haemodynamic changes of neuroleptanaesthesia were almost identical to those of the combined epidural-general anaesthesia. For the operation which followed, a continuous infusion of 0.125 per cent plain bupivacaine (0.25 ml/kg X h) via epidural catheter (in combination with N2O/O2-anaesthesia) was sufficient for complete analgesia in the epidural group. These findings lead to the conclusion that a small bolus volume and a low concentration of bupivacaine result in good anaesthesia while avoiding serious haemodynamic alterations.

Adult↗
PubMed1985

The influence of ketamine on both normal and raised intracranial pressure of artificially ventilated animals.

The effect of two different doses of ketamine, 0.5 mg kg-1 body weight, and 2.0 mg kg-1 body weight, on intracranial pressure and cerebral perfusion pressure were investigated in 21 young pigs (26-34 kg) under controlled artificial ventilation. Three groups each containing seven animals were studied: Group 1. Initially normal blood pressure and an intracranial pressure within the normal range (10.7 mmHg). Group 2. Normal blood pressure and increased intracranial pressure caused by inflating an epidural balloon (29.2 mmHg). Group 3. Increased intracranial pressure (32.7 mmHg) and mean arterial pressure reduced by approximately 30% through controlled haemorrhage. There was no increase in intracranial pressure from either normal or initially increased values. This applied to animals with normal blood pressure values and also to those in haemorrhagic shock. This observation can be explained by the lack of an increase in PCO2 under controlled ventilation. During haemorrhagic shock cerebral perfusion pressure fell significantly as a result of the fall in mean arterial pressure. This particularly applied to the 2.0 mg kg-1 dose of ketamine. We therefore consider volume substitution to be essential in this situation.

Animals↗
PubMed1984

[New developments in operative medicine--anesthesiology].

New developments in anaesthesiology include: Preoperative analysis of the patients' risk, evaluation and treatment of preexisting illnesses in an increasing number of risk patients. The intraoperative use of a combination of different anaesthetic procedures, and an individually adapted monitoring. The postoperative surveillance, correction therapy in the recovery unit, continuation of treatment with improved intensive care methods.

Anesthesiology↗
PubMed1984

The early use of positive end expiratory pressure (PEEP) ventilation in emergency medicine, and some experiments on pigs.

The effects on near drowning of young pigs of positive end expiratory pressure and zero end expiratory pressure were studied. The arterial PO2 and blood gases were examined during recovery from near drowning and after haemorrhagic shock. The cardiovascular parameters were measured after shock. The findings were considered in relation to the use of positive and expiratory pressure in patients. It was recommended that it be only administered by experienced staff in hospitals, and should not exceed 10 mbars, while 5 mbar was adequate and avoided complications in most cases.

Animals↗
PubMed1984

[Animal experiment study on the modification of increased intracranial pressure by THAM (tris-hydroxymethylaminomethane) and sodium bicarbonate].

Intracranial pressure was increased by means of an epidural balloon in 21 young pigs anaesthetised with air/O2 and burprenorphine. Sodium bicarbonate (1 mmol/kg BW) was administered intravenously in 10 animals; THAM (tris-hydroxymethylaminomethane) (1 mmol/kg BW), in 11. Intracranial pressure declined significantly under THAM, from 4.35 kPa in the middle of the infusion to 3.92 kPa at the end, and continued to drop for 15 minutes after its termination. No changes in intracranial pressure, however, were observed in the bicarbonate group. Since mean arterial blood pressure was unchanged in both groups, the increase in cerebral perfusion pressure was significant in the THAM group, but not in the bicarbonate group. Our results, therefore, indicate that THAM is preferable to bicarbonate for correcting acidosis in acute craniocerebral trauma. Controlled ventilation, however, remains indispensable.

Animals↗
PubMed1984

[Parenteral administration of amino acids. Reference values--study technic--interpretation of the study results--amino acid pattern as a criterion of the regulation of homeostasis].

The concentrations of free amino acids were measured in lithium-heparinat-plasma with a standardized quality controlled analytical procedure in 200 healthy persons (blood donors). The distribution of the measured values were statistically evaluated in the total group and differentiated in the male and female subcollective. The absolute total concentrations of the free amino acids vary in a broad range between 1.7 and 4.4 mmol/l. This large range is also seen for the single amino acid. In a new system for documentation and interpretation of analytical data the measured values are collected and mean, median, standard deviation, mini-max-range and 95% confidence interval are automatically computed. On this basis of data a physiological reference range is defined. The broad variability of the absolute concentrations is not found in the relative composition of the pattern. The relations of the amino acid concentrations which are important for the quality of the cellular support are very constant. Their importance is caused by the fact that only few different transport systems exist for at least 20 amino acids, which means that the different amino acids are competing at the same system for cellular uptake. The essential of the results in this study is that the liver guarantees the constancy of the physiological pattern also in cases where the exogenous supply differs from the characteristics of elimination of the single amino acid from blood. Only when the oxidative capacity of the liver is insufficient as in pathological states like infections pathological concentrations are found. In these cases the true change is undiscovered when the absolute concentrations are considered, because the insufficient functions of the liver causes initially high total concentrations. For the interpretation of an analysis of amino acids in blood plasma two main criteria are necessary: the total concentration of amino acid characterizes the quantitative support while the concentration pattern determines the quality of the cellular uptake.

Adult↗
PubMed1984

[Acute coronary insufficiency during induction of anesthesia following anthracycline chemotherapy].

Cytostatic treatment with anthracyclines lines can lead to acute or chronic myocardial insufficiency. A cumulative dose of less than 500 mg/m2 body surface area can in general be regarded as safe. A case of acute cardio-circulatory insufficiency during induction of anesthesia is described, in which the total cumulative dose did not exceed 250 mg/m2 body surface area. The pathophysiological mechanisms occurring and the diagnostic and therapeutic measures necessary are discussed.

Anesthesia↗
PubMed1984

[Energy metabolism and energy consumption of intensive care patients on respirators].

There are two main reasons for assessing energy turnover individually and as accurately as possible; firstly, the marked variation in available data on the degree to which energy turnover increases after severe trauma, and secondly accumulating evidence of the potential dangers of an inappropriately high so-called "hypercaloric" substrate dosage, which exceeds energy requirements. The energy turnover of 50 polytraumatized intensive care patients was therefore measured by indirect calorimetry and compared with norm values. Comparison of the median values revealed an approximately 50% higher energy turnover in the polytraumatized cases than calculated basal levels. The median values of our patients all lay within a similar range, but for each individual case we found marked differences between the energy turnover as measured by indirect calorimetry, and that estimated from norm tables. The oxygen consumption and CO2 production rates of 10 polytraumatized ventilated patients, measured at short time intervals, showed only minimal variations during the course of 24 h. The separate measurements carried out at hourly intervals varied by less than 10% when compared to an 1-h period of observation between 11 and 12 a.m. The oxygen consumption of a group of 40 polytraumatized, ventilated intensive care patients receiving various different i.v. infusions and parenteral nutrition regimens was, with an average of 382 +/- 47 ml/min, much higher than physiologically normal values. The energy turnover rate of these patients was correspondingly much higher than that of a fit person at rest, despite the fact that the rates measured were relatively low when compared to values found in the older literature.(ABSTRACT TRUNCATED AT 250 WORDS)

Calorimetry, Indirect↗
PubMed1983

[The stress reaction in knee operations under continuous peridural anesthesia in comparison with neuroleptanalgesia].

30 patients undergoing knee-operations were randomized in two groups. 15 patients were operated on under neuroleptanalgesia. Piritramid was given postoperatively. The other group of patients was operated under epidural analgesia, postoperatively they were kept painfree by continuous infusion of 0.2% bupivacaine via an epidural catheter at a rate of 0.2 ml/kg.h over a period of 24 h. The aim of our study was to find out if continuous epidural anaesthesia in contrast to neurolept analgesia was able to prevent the hormoneal and metabolic response to these painful operations. Plasma glucose, insulin, C-peptidee, glucagon, cortisol, human growth hormon, and beta-hydroxybutyric acid were measured before commencing anaesthesia (point 0), after induction (point N), at the end of operation (point Op) and 1, 2, 4, 6, 12 and 24 h postoperatively (point 1, 2, 4, 6, 12 and 24). In both groups of patients an intravenous glucose tolerance test was carried out after 24 h. There were significant differences between the two groups in plasma glucose, insulin, C-peptid and cortisol, indicating that the stress response can be mitigated by continuous epidural anaesthesia. These differences however were only found in the first few postoperative hours. After a period of 24 h there were no differences at all, the metabolic alterations as indicated by the pathological glucose tolerance test, were the same in both groups, independent of the anaesthetic method used.

3-Hydroxybutyric Acid↗
PubMed1983

[Coagulation disorders in acute cranio-cerebral injuries].

Marked coagulation defects which have a very high mortality rate can arise following acute head injury. Damage to brain tissue leads to the release of substances promoting coagulation which can enter the vascular system and activate the enzyme cascade leading to clot formation. The more widespread cerebral damage is, the greater is the likelihood of clinically relevant DIC occurring. By carrying out clotting tests and taking therapeutic measures where necessary, a potentially lethal outcome can be avoided.

Acute Disease↗
PubMed1983

[Experience with a simple form for the evaluation of surgical risk due to nutritional status].

The diagnosis and determination of the nutritional status for the evaluation of a surgical risk is achieved on the basis of a simple documentation scheme: The aim of the presented study was the characterization of this specific check-up protocol to find out the usefulness and applicability of this scheme and its value for the recognition of the nutritional status as one of the factors determining the outcome of surgical patients. The results show that this simple procedure allows an equivalent ranging of patients in different classes of nutrition related states as the highly sophisticated, time, costs and staff consuming protocols which were published to define nutritional states in the last years. When the exact and differentiated status is not necessary the simple protocol gives the same information to judge the possible risk by nutritional deficiencies as the complicated protocols.

Female↗