PubMed Health⌕ Search

Biomedical subjects

F W Ahnefeld

Publications and source records attributed to F W Ahnefeld.

At least 19 recordsLinked to original sources
PubMed1992

Relationship between arterial and peripheral venous catecholamine plasma catecholamine concentrations during infusion of noradrenaline and adrenaline in healthy volunteers.

Noradrenaline and adrenaline were infused IV at 5 different rates (0.01-0.2 micrograms.kg.min-1) for 30 min to volunteers. The plasma catecholamine concentrations were determined by HPLC and electro-chemical detection. At the highest infusion rate, the arterial and venous plasma concentrations of noradrenaline increased from 1.18 to 44.1 nmol.l-1 and from 1.14 to 31.9 nmol.l-1, respectively, and of adrenaline from 0.29 to 23.9 nmol.l-1 and from 0.28 to 19.3 nmol.l-1, respectively. The peripheral venous plasma concentration of noradrenaline averaged 76% of the arterial concentration, and of adrenaline it was 73%. There was a linear relationship between the peripheral venous and arterial plasma noradrenaline and adrenaline concentrations at therapeutic doses.

Adult↗
PubMed1992

Stress hormone response during and after cardiopulmonary resuscitation.

The purpose of this study was to assess whether plasma adrenocorticotropin, cortisol, vasopressin, and renin concentrations are higher in resuscitated than in nonresuscitated patients during cardiopulmonary resuscitation, and whether there are possible correlations between these hormones and blood pressure or heart rate in the immediate postresuscitation phase. Of 34 consecutive patients (36-85 yr of age) with out-of-hospital cardiac arrest, 20 could be successfully resuscitated and admitted to hospital, whereas in the remaining 14 patients restoration of spontaneous circulation could not be achieved. During cardiopulmonary resuscitation, median adrenocorticotropin, cortisol, vasopressin, and renin concentrations in the external jugular vein were 237 pg/ml, 32.6 micrograms/dl, 122 pg/ml, and 46.5 ng/l, respectively, in resuscitated patients, and 45 pg/ml (P = 0.018), 18.4 micrograms/dl (P = 0.481), 88 pg/ml (P = 0.049), and 11 ng/l (P = 0.017), respectively, in nonresuscitated patients. Median adrenocorticotropin, cortisol, vasopressin, and renin concentrations were 101 pg/ml, 34.6 micrograms/dl, 22 pg/ml, and 25 ng/l, respectively, 60 min after successful resuscitation. No significant correlations were found between hormone levels and blood pressure or heart rate, but there was a significant negative correlation between the interval from collapse to the start of cardiopulmonary resuscitation and plasma cortisol concentrations during cardiopulmonary resuscitation (Spearman rank correlation coefficient = -0.967, P less than 0.001), indicating an impaired cortisol release from the adrenal cortex. The lower hormone concentrations of the nonresuscitated patients measured during cardiopulmonary resuscitation might indicate an impairment in neuroendocrine response.

Adrenocorticotropic Hormone↗
PubMed1992

Relationship between infusion rates, plasma concentrations, and cardiovascular and metabolic effects during the infusion of norepinephrine in healthy volunteers.

OBJECTIVE: To determine the relationship between iv infusion rate, plasma concentrations, and hemodynamic and metabolic actions of norepinephrine. DESIGN: Norepinephrine was administered by using five iv infusion rates (0.01 to 0.2 micrograms/kg/min) for 30 mins each to eight volunteers, for the purpose of constructing cumulative plasma concentration-response curves. SETTING: Laboratory of the Department of Anesthesiology at a university hospital. MEASUREMENTS AND MAIN RESULTS: Systolic and diastolic BP, heart rate, and the plasma concentrations of norepinephrine, glucose, nonesterified fatty acids, and insulin were measured at the end of each infusion rate. During the highest infusion rate, plasma norepinephrine concentrations increased from 199 +/- 75 to 7475 +/- 1071 pg/mL (1.18 +/- 0.44 to 44.18 +/- 6.33 nmol/L). Typical hemodynamic responses, such as increases in BP and decreases in heart rate, were seen, while the plasma concentrations of glucose and nonesterified fatty acids increased from 92 +/- 10 to 132 +/- 17 mg/dL (5.1 +/- 0.6 to 7.3 +/- 0.9 mmol/L) and 11 +/- 4 to 34 +/- 6 mg/dL (0.11 +/- 0.04 to 0.34 +/- 0.06 g/L), respectively, during the 0.2 micrograms/kg/min infusion rate (p less than .05). Despite the increase in glucose concentration, insulin remained at baseline values. Metabolic and hemodynamic effects occurred at similar plasma concentrations throughout the study. CONCLUSIONS: Administration of norepinephrine showed no selective hemodynamic actions. The metabolic responses observed in this investigation were similar to those responses seen during increased endogenous sympathetic nervous system activity, such as stress, exercise, or trauma.

Adult↗
PubMed1992

Measurement of mucociliary transport velocity in ventilated patients. Short-term effect of general anesthesia on mucociliary transport.

OBJECTIVES: The objectives of this study were to evaluate a method for measuring BTV in ventilated patients and to study the short-term effect of general anesthesia with midazolam, Fentanyl, pancuronium and O2:N2O on BTV. DESIGN: The study included phantom measurements on a bronchoscopy model and the determination of BTV in patients in a convenience sample trial. SETTING: The study took place in a university hospital. PATIENTS: Fourteen patients undergoing major abdominal surgery with planned postoperative mechanical ventilation were included in the study. All patients gave their written informed consent to participate in the study. INTERVENTIONS: Bronchial mucus transport velocity was measured with a small volume (0.05 to 0.08 ml) of technetium 99m-labeled albumin microspheres with an activity of 3 MBq. The radiolabeled bolus was deposited on the dorsal mucosal surface at the distal end of the right and left main bronchus via flexible bronchoscopy. The movement of the microspheres toward the trachea was visualized and recorded using a scintillation camera; quantitative evaluation utilized the condensed image. MAIN MEASUREMENTS AND RESULTS: The technique was validated in a bronchoscopy model and in an intubated patient by moving a radioactive drop in a catheter through the main bronchi at velocities from 0 to 20 mm/min. The velocities determined by the image processing technique correlated well with the data by the model and patient determination (right bronchus, r = 1.0; left bronchus, r = 1.0). In seven ventilated patients, mechanical irritation by the fiberscope produced no significant effect on BTV. The BTV was measured preoperatively in seven conscious patients one day before surgery while they received local anesthesia with 10 ml of 1 percent lidocaine and postoperatively while they received intubation anesthesia. The preoperative and postoperative BTV values showed no significant differences (10.5; 5.7 to 13.7 mm/min; vs 9.7 (3.7 to 15.3) (median with range). CONCLUSION: By this method, bronchial transport velocity can be determined in a relatively short time in ventilated patients. General anesthesia with midazolam, Fentanyl, pancuronium and O2:N2O does not influence BTV.

Adult↗
PubMed1992

Adrenaline: relationship between infusion rate, plasma concentration, metabolic and haemodynamic effects in volunteers.

The present study investigated the relationship between supraphysiological plasma concentrations of adrenaline and the resulting haemodynamic and metabolic effects. Adrenaline was administered at five infusion rates (0.01-0.2 micrograms kg-1 min-1) in an escalating sequence to eight volunteers. The arterial plasma concentration of adrenaline increased from 53 +/- 44 to 4349 +/- 818 ng litre-1 during the highest infusion rate. Typical haemodynamic responses, such as increase in blood pressure and heart rate, were seen. The plasma concentrations of glucose and lactate increased from 5.2 +/- 0.4 to 13.7 +/- 1.3 mmol litre-1 and from 0.9 +/- 0.3 to 4.7 +/- 2.6 mmol litre-1, respectively, during the highest infusion rate without a significant increase in insulin concentration. Non-esterified fatty acids increased from 379 +/- 97 to 1114 +/- 331 mumol litre-1 during the 0.06 microgram kg-1 min-1 infusion rate. Adrenaline had no selective haemodynamic effect. If similar metabolic effects occur in patients during treatment with adrenaline or other sympathomimetics, they may further increase breakdown of energy stores in a situation of increased catabolism, and impair utilization of parenteral nutrition.

Adult↗
PubMed1979

[Sorbitol and xylitol in post-operative infusion therapy (author's transl)].

The effect of a 24-hour continuous infusion of sorbitol in the recommended maximum dosage of 0.25 g . kg-1 . h-1 or of xylitol in the recommended maximum dosage of 0.125 g . kg-1 . h-1 on metabolic parameters was investigated in seven healthy adult men. The results demonstrate the continued applicability for longer than the recommended time as well as the acceptability of continuous infusion of polyols used clinically with combined solutions.

Adult↗
PubMed1979

[Effects of ventilation with defined formaldehyde concentrations on lung function and lung structures. Animal experiments on the noxiousness of formaldehyde residues after disinfection in the aseptor (author's transl)].

Having seen the development of fatal pneumonias in ventilated patients, the cause of which was assumed to be the presence of residual traces of formaldehyde in the air in the respirator Kilian and Haug showed in 1973 initial formaldehyde concentrations up to 0.2 ppm in the ventilatory air of respirators correctly disinfected in the Aseptor. To study the effects of formaldehyde on lung function and lung structures, 23 young pigs were automatically ventilated with defined formaldehyde concentrations during 6 hours. The concentrations used were 0.02 ppm, 0.2 ppm and 2.0 ppm (double of the maximum permissible concentration). We found no differences in lung function, as shown by compliance measurements and arterial blood gas analysis. No radiological differences were in the thorax. Histologically, there were only slight alterations in lung structure in the group ventilated with double the maximum permissible concentration of formaldehyde. We conclude that the disinfection of respirators using formaldehyde in the Aseptor will remain the method of choice.

Animals↗
PubMed1979

[Infusions emergencies following the administration of plasma substitutes -- analysis of case reports to the committee on drugs. The problems of medical statistics, prophylaxis and immediate therapy (author's transl)].

In the period 1967 to 1976 the Adverse Drug Reaction Committee of the Medical Association of the Federal Republic of Germany (AMK) received 323 reports of transfusion emergencies following the administration of colloid plasma expanders (dextran, gelatin, starch). The reports ranged from medium to severe cases. Nine percent of the reported cases had a fatal outcome. The data contained in these case reports could only be statistically analyzed within certain limitations as the reports were incomplete and other parameters necessary for a definite statistical evaluating were missing. Furthermore the results do not cover the following points: 1. What percentage of reactions to plasma expanders in W. Germany was reported? --2. What percentage can be attributed to the individual colloids within the entirety of these undesirable side effects? --3. What percentage of the individual colloids can be allocated to the varying degrees of severity of these reactions? -- Further limitations which complicated the analysis of the case reports are discussed individually. Despite these difficulties an attempt was made to analyse the parameters necessary in the diagnosis of acute transfusion emergencies and to compile a guide for the clinical symptomatology. Grading of reactions into four degrees of severity has proved useful both in terms of diagnosis and immediate therapy. The medical statistical evaluation presented in this paper gives an indication as to the significance of the observed side-effects and confirms the statement and recommendations made elsewhere in the literature. In these emergency cases life-threatening incidents appear to be more common than is generally assumed and the user is aware of. The incidence of product-specific emergencies can only be determined to some degree of accuracy by randomized prospective studies. These would have to be conducted with numerous strict guidelines. On the basis of the results presented here, these studies should be attended to with a sense of urgency. Regardless of the difficulties encountered in the evaluation of the case reports, guidelines as to the recognition of reactions, prophylaxis and immediate remedial therapy could be established. These would appear to suffice as urgently required comprehensive information for the nursing staff as well as all doctors. Recognizing side-effects and instituting immediate remedial therapy along the principles laid down in these guidelines can in most cases of severe reactions remove the acute threat to life.

Adolescent↗
PubMed1979

[A new suction pump to be used in the field of emergency medicine (author's transl)].

In the field of emergency medicine there has been a need for an efficient suction pump that can be used under all types of conditions and included both in doctors' emergency kits as well as in the standard equipment of mobile units such as ambulance cars, helicopters etc. The devices available in the past had decided disadvantages in their construction and performance. A newly designed suction pump -- the AMBU Uni-Suction -- has been subjected to laboratory and practical tests concerning function, material and practical use, based on a specification of requirements for such a device. The results show that this universally applicable suction pump meets every requirement under the different test conditions. The effectiveness is good, irrespective of the mode of operation applied, i.e. by hand, by foot or by compressed gases. Maintenance and service are negligible and no susceptibility to malfunction was observed. In addition, the design, function and performance of an accessory unit, the Suction Booster, are presented. This device can be used effectively in combination with the new suction pump, or with any other type of suction unit to prevent dangerous aspiration in emergencies.

Clinical Trials as Topic↗
PubMed1978

[Indications and possibilities for parenteral nutrition (author's transl)].

Parenteral nutrition is a basic therapy. It is necessary to have a preoperative definition of the nutritional condition and metabolism of the surgical patient. All disturbances such as catabolism and hypoproteinemia must be analyzed and treated. Patients in good general condition who need parenteral nutrition for more than two days receive a "basic nutrition" with 0.8-1.0 g amino acids and 4-5 mg carbohydrates/kg body weight/day, which may be given via peripheral veins. A "total parenteral nutrition" is always indicated if the patient is in a marked catabolic condition pre-operatively, or if it is anticipated from the extent of the operation procedure that parenteral replacement must continue beyond four days.

Amino Acids↗
PubMed1978

A new positive end-expiratory pressure valve for manually operated artificial ventilation.

The application of positive end-expiratory pressure (PEEP) as part of artificial ventilation is currently considered a basic provision to provide adequate treatment of critically ill patients in intensive care units. Hitherto only the application of intermittent positive pressure ventilation (IPPV) with an end-expiratory pressure of 0 cm water was possible during manually operated artificial ventilation. A new PEEP valve which can be attached to manually operated resuscitators has been developed in co-operation with industry to meet this need. The technical details and experimental testing of the new valve have been presented in this paper. It may be connected via special adaptors to existing Ambu resuscitators, either for use on adults or on neonates, babies and infants. The valve has the characteristics of normal PEEP devices in that the resistances with various PEEP levels remain relatively independent of the flow and thus presents a true positive end-expiratory pressure rather than just an increase of expiratory resistance. The valve can be connected simply to nearly all types of simple and advanced respirators, such as those used for assisting respiration, physiotherapy etc., as well as being used with manually operated resuscitators.

Adult↗
PubMed1978

[Clinical study on the concentration of free amino acids in plasma and urine during postaggression metabolism. I].

We studied the changes in the concentration pattern of free plasma amino acids in 30 surgical patients during standardized parenteral nutrition and exclusive water and electrolyte supply. Distinct reproducible differences were found in comparison to normal subjects. The concentration of branched-chain amino acids continuously increases during the post-operative period. The decrease of alanine is closely related. Phenylalanine also increases continuously due to insufficient transformation in the liver and increased release from the muscles. During post-aggression metabolism, cystine is probably not sufficiently formed from methionine and should be substituted. It may be that tyrosine is also essential for patients in the post-operative post-traumatic period. The glycine concentration of some amino acid mixtures is regarded as too high; the glycine content can be reduced in favour of serine supply.

Amino Acids, Essential↗
PubMed1978

[Clinical studies on the concentration of free amino acids in plasma and urine during post-aggression metabolism. II].

Our first report concerned the changes in the concentration of free plasma amino acids within the framework of postaggression metabolism, resulting from surgical intervention and parenteral nutrition. This study with 23 operated patients is intended to show whether an amino acid mixture is suited for parenteral nutrition if the particular metabolic action mentioned above is taken into consideration in the composition of the solution. We have shown that the change in the concentration of free plasma amino acids is very small during continuous infusion for 4 postoperative days in steady state and insignificant in comparison to the normal pattern of healthy subjects, except for phenylalanine. With a quota of 2.75% of the supply, the renal loss of free amino acids is clinically unimportant. We believe that an amino acid solution of such composition is suited for infusion in the postoperative and posttraumatic phase whereby our recommendation is explicitly limited to this indication.

Amino Acids↗
PubMed1978

[Possibilities and limitations of peripheral-venous parenteral feeding].

The possibilities of peripheral-venous nutrition as regards its substrate dosage are limited due to the vein tolerance (osmolarity) of the infusion mixtures. It is, therefore, imperative to achieve an optimum composition of the solution for obtaining the most favourable utilization rate for the organism. We have shown that a dosage below 0.6 g amino acids/kg BW per day does not have a positive influence on the nitrogen balance in comparison to a control group not nourished. The situation of a patient in the post-aggression phase results in 30 to 40% of the supplied amino acids being utilized in the energy metabolism and excreted as urea, in spite of a sufficient simultaneous energy supply. Not only does this uneconomical loss alone necessitate a higher amino acid dosage, but also the additionally increased catabolism of endogenous protein reserves in the post-operative phase. It remains to be tested whether the sole substitution of amino acids in a solution without carbohydrates over a short infusion period constitutes a compromise between the intended peripheral-venous tolerance and an effect on the nitrogen balance.

Amino Acids↗