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Biomedical subjects

F W Ahnefeld

Publications and source records attributed to F W Ahnefeld.

At least 55 records · Page 3Linked to original sources
PubMed1990

Endobronchial drug administration: does deep endobronchial delivery have advantages in comparison with simple injection through the endotracheal tube?

Endobronchial administration of drugs is a valuable alternative to intravenous delivery when venous access cannot be established quickly enough. Some authors propose that deep endobronchial administration through a catheter or similar auxiliary device should give better absorption than simple injection through the endotracheal tube. To test this proposal in the present study two groups of each 6 patients during general anesthesia were administered 3 ml aqueous lidocaine solution at a dose of 2 mg/kg, either deep endobronchially through a catheter or simply through the endotracheal tube. The unusually low volume of administration of 3 ml was chosen because it was thought that the advantages of deep endobronchial administration would then be particularly apparent as 3 ml would lead to a more localized deposit with deep endobronchial administration thus being clearly different from simple injection. No difference in the PaO2 between the two groups could be statistically established. However, the mean lidocaine plasma concentration in the group with the deep endobronchially administered drug was in tendency lower than in the control group (P less than 0.05 at 5 min after delivery). Presumably because of the low volume of administration the mean lidocaine plasma concentrations in both groups always remained under the therapeutic level of at least 1.5 micrograms/ml. Thus, at least for small volumes and stable circulation the results after deep endobronchial administration through a catheter were somewhat worse than after simple injection through the endotracheal tube.

Adult↗
PubMed1990

What is the optimal volume of administration for endobronchial drugs?

During general anesthesia, three groups of six patients each received 2 mg/kg lidocaine as a marker substance endobronchially in either 10, 5, or 3 mL distilled water. It was found that the group receiving 10 mL initially exhibited the highest lidocaine plasma concentration with a mean of 2.01 micrograms/mL, in comparison with 1.25 micrograms/mL in the 5 mL group and 0.95 micrograms/mL in the 3 mL group. After about 10 minutes, concentration courses were almost the same in the 10 mL and the 5 mL groups. The PaO2 in the 10 mL group dropped initially by approximately 40 mm Hg on average and remained low over 60 minutes. By this time the PaO2 in the 5 mL group (initial drop 46 mm Hg) had come back to the original value (P less than .05). The 3 mL group exhibited even more favorable courses in the PaO2 (initial drop 16 mm Hg on average). However, the lidocaine plasma concentration was at the lowest at all times in this group and, moreover, under the therapeutic level of 1.5 micrograms/mL with the dosage used.

Absorption↗
PubMed1990

Effects of epinephrine and norepinephrine on cerebral oxygen delivery and consumption during open-chest CPR.

The effect of epinephrine and norepinephrine on cerebral oxygen delivery and consumption after five minutes of cardiopulmonary arrest and three minutes of open-chest cardiac massage was studied in 21 pigs. Norepinephrine, like epinephrine, has a marked alpha- and beta 1-sympathomimetic activity, but compared with epinephrine, the degree of beta 2-stimulation is weak. Epinephrine probably stimulates cerebral oxygen and glucose consumption by its beta 2-adrenergic effect. After three minutes of CPR, three groups of seven animals each blindly received either placebo (control group), 45 micrograms/kg epinephrine, or 45 micrograms/kg norepinephrine. During CPR but before drug administration, cerebral blood flow was 23 +/- 14 mL/min/100 g in the control group, 30 +/- 7 mL/min/100 g in the epinephrine group, and 30 +/- 11 mL/min/100 g in the norepinephrine group. At 90 seconds after epinephrine, cerebral blood flow increased to 54 +/- 14 mL/min/100 g and after norepinephrine, to 58 +/- 22 mL/min/100 g (P less than .05). Cerebral perfusion pressure for both drugs was significantly higher than the control group. Compared with mechanical measures alone, cerebral oxygen delivery rose from 4.3 +/- 1.2 to 7.4 +/- 1.7 mL/min/100 g after epinephrine and from 3.7 +/- 1.4 to 7.3 +/- 2.7 mL/min/100 g after norepinephrine (P less than .05). There was no increase in cerebral oxygen consumption after both catecholamines, and cerebral oxygen extraction ratio decreased. Cerebral glucose delivery increased in relation to glucose consumption, and extraction ratio did not change significantly after both catecholamines.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Plasma lidocaine levels and PaO2 with endobronchial administration: dilution with normal saline or distilled water?

STUDY OBJECTIVE: To determine whether water or 0.9% saline should be used as diluent for endobronchial drug administration. PARTICIPANTS: Twelve adult patients. INTERVENTIONS: Patients were endobronchially administered 2 mg/kg lidocaine as marker substance in either 10 mL 0.9% saline or 10 mL distilled water during general anesthesia. MEASUREMENTS AND MAIN RESULTS: The differences in mean lidocaine plasma levels at five minutes (water vs saline, 2.35 vs 1.59 micrograms/mL) and ten minutes (water vs saline: 2.67 vs 1.88 micrograms/mL) were significant (P less than .05). With the initial mean PaO2 being almost (157 mm Hg; F1O2, 0.3) in the two groups, there was a mean drop of about 60 mm Hg in the saline-diluent group, but only about 40 mm Hg in the water-diluent group one minute after administration (P less than .05). CONCLUSION: The use of water resulted in better absorption of lidocaine and less impairment of the PaO2.

Adult↗
PubMed1990

Cardiopulmonary resuscitation with interposed abdominal compression after asphyxial or fibrillatory cardiac arrest in pigs.

The purpose of this study was to compare the efficacy of standard cardiopulmonary resuscitation and cardiopulmonary resuscitation with interposed abdominal compression for restoration of spontaneous circulation in an asphyxial and fibrillatory arrest model. Twenty-eight pigs weighing 19-27 kg were randomly allocated to two arrest groups. Each of these two groups was then subdivided into a treatment group and a control group resulting in four groups of seven pigs each. In the control groups standard cardiopulmonary resuscitation was performed with a pneumatically driven chest compressor at a rate of 80 beats per min. The animals' lungs were ventilated at a respiratory rate of 20 breaths per min independently of chest compression. In the treatment group, in addition to standard cardiopulmonary resuscitation, manual interposed abdominal compression was applied at the midabdomen in the second half of the relaxation phase using a blood pressure cuff to measure and standardize the compressions. Following asphyxial cardiac arrest of 3 min, none of the seven animals could be resuscitated with standard cardiopulmonary resuscitation, whereas all seven animals could be resuscitated with interposed abdominal compression and standard cardiopulmonary resuscitation after 240 +/- 84 s. Following fibrillatory cardiac arrest of 4 min, none of the seven animals that received standard cardiopulmonary resuscitation and countershocks could be resuscitated. In the group that received standard cardiopulmonary resuscitation and interposed abdominal compression spontaneous circulation was achieved in all animals in 244 +/- 117 s. End-diastolic arteriovenous pressure difference, which correlates with coronary blood flow, was significantly higher with interposed abdominal compression during resuscitation from both forms of cardiac arrest. The results of our study indicate that cardiopulmonary resuscitation with interposed abdominal compression in the second half of the relaxation phase improves diastolic arteriovenous pressure difference and resuscitation success in comparison with that following standard cardiopulmonary resuscitation. The use of interposed abdominal compression during basic cardiac life support should be investigated further in patients.

Abdomen↗
PubMed1990

Anti-lipopolysaccharide-immunoglobulin (IgG-anti-LPS) therapy in intensive care patients following surgery from infectious disease.

In 18 intensive care patients the effect of a IgG-Anti-Lipopolysaccharide (Anti-LPS), was investigated in a randomized study following surgery after bacterial infections, mostly peritonitis. Fresh frozen plasma was administered during the first 5 postoperative days, containing either more than 65 micrograms/ml Anti-LPS in the therapy group or less than 12.5 micrograms/ml in the control group. The serum level of Anti-LPS was monitored. Clinical and chemical parameters were recorded to evaluate infectious complications and outcome of the patients. The mortality in the treatment group was not different from the control group with 30% (3 out of 10) and 25% (2 out of 8), respectively. No beneficial effect was observed either from the administration of Anti-LPS or from endogenously produced Anti-LPS on any clinical parameter in our patients.

Adult↗
PubMed1990

Epinephrine and norepinephrine in cardiopulmonary resuscitation. Effects on myocardial oxygen delivery and consumption.

Norepinephrine, an alpha 1,2-beta 1,2-adrenergic agonist, seems to be an alternative to epinephrine, an alpha 1,2-beta 1,2-agonist, for restoration of spontaneous circulation in VF. We therefore studied the effect of epinephrine and norepinephrine on MDO2 and MVO2 using OCCM after five minutes of cardiopulmonary arrest in 21 pigs. After OCCM of three minutes, seven animals each received placebo (controls) or epinephrine (45 micrograms/kg) or norepinephrine (45 micrograms/kg). All drugs were given blindly. At 90 seconds after epinephrine or norepinephrine, mean arterial blood pressure was significantly higher than in the control group. Prior to cardiac arrest, MBF, measured with radioactive microspheres, was 193 +/- 30 ml/min/100 g. During CPR but before drug administration, MBF was 51 +/- 23 in the control group, 71 +/- 10 in the group with epinephrine, and 74 +/- 11 ml/min/100 g in the group with norepinephrine. At 90 seconds after epinephrine, MBF increased to 126 +/- 18 and after norepinephrine to 107 +/- 30 ml/min/100 g (p less than 0.05). Compared to OCCM alone, MDO2 increased from 9.6 +/- 1.7 to 17.1 +/- 3.2 ml/min/100 g after epinephrine and from 9.4 +/- 1.8 to 13.6 +/- 4.2 ml/min/100 g after norepinephrine (p less than 0.05). There was an increase in MVO2 from 4.0 +/- 1.5 to 9.4 +/- 3.0 ml/min/100 g after epinephrine (p less than 0.05), whereas MVO2 increased only from 4.2 +/- 0.8 to 5.1 +/- 2.0 ml/min/100 g after norepinephrine. Because epinephrine led to a greater increase in MVO2 than norepinephrine, the myocardial oxygen ER remained unchanged. The oxygen requirements of the fibrillating heart seemed to be increased via beta 2-adrenergic stimulation. In both the control and epinephrine-treated groups, only three of the seven animals could be successfully resuscitated, whereas all of the animals in the group with norepinephrine survived the 15-minute period of observation. In this model, norepinephrine, in contrast to epinephrine, improves the balance between MDO2 and MVO2 and eases restoration of spontaneous circulation.

Animals↗
PubMed1990

[Comparative studies of administration of xylitol or glucose in parenteral infusion of amino acids in critical care patients].

In a prospective, randomized study, two different concepts of carbohydrate application in the postoperative state were investigated and statistically analyzed in 20 intensive care patients in each group. Aim of the study was to evaluate influences of glucose or xylitol infusions in critically ill patients. Under the strict control of prerequisites for the application of parenteral nutrition in general and the application of specific substrates specifically, the study is based on the hypothesis that adverse reactions of the substrates like hyperglycemia should not occur. As a main result of the study, statistical significances of differences between the two groups could not be substantiated. The only difference between the two groups of severely ill patients with ventilation and hemodynamic support was an instability in glucose concentrations in blood under the application of glucose. Some patients in that group showed an increase in glucose concentration, which made insulin therapy necessary. We conclude that glucose is also applicable under the marked hormonally fixed conditions of postoperative metabolism if a narrow control of glucose is performed with an interruption of glucose application when concentrations increase. Also, on the basis of our data, xylitol showed a higher degree of security because under application of this substrate changes of glucose did not occur. In all cases where physiological conditions are achieved, glucose is the first choice of carbohydrates. In all those cases where the possibility exists that behind a normalized glucose concentration alterations of metabolism may be hidden, the application of xylitol offers the possibility to avoid imbalances and substrate load.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗
PubMed1990

[The modification of the potassium concentration in blood by catecholamines. A literature review].

After intravenous administration of epinephrine, serum potassium level shows a typically biphasic course. The initial rise is followed by a persistent fall to a lower level than the starting-concentration. The initially observed hyperkalemia is supposed to be caused by a potassium release from hepatocytes, mediated by an alpha 1-adrenoreceptor stimulation. The subsequent hypokalemia seems to be caused by the beta 2-mimetic component of epinephrine effecting the uptake of this ion into striated muscle cells. There are numerous clinical reports of marked hypokalemia as a consequence of beta 2-mimetic therapy. The additive effect of elevated endogenous catecholamines with the therapeutically applied epinephrine during cardiopulmonary resuscitation may be the cause of the elevated potassium levels often observed under these conditions. On the other hand, low serum potassium levels were measured in patients after successful resuscitation, as well as in patients with multiple trauma and with severe head injury. Moreover, hypokalemia seems to be a frequent event in the acute phase of myocardial infarction. A catecholamine-induced potassium shift into the cell is considered to be the cause of this decrease. The question whether in the case of myocardial infarction the hypokalemia is in itself arrhythmogenic as yet is not resolved. Because of the present knowledge about the influence of catecholamines on potassium metabolism it seems advisable to monitor potassium levels regularly during the above situations.

Epinephrine↗
PubMed1989

Comparison of epinephrine and dopamine during cardiopulmonary resuscitation.

The effectiveness of epinephrine and dopamine for restoring spontaneous circulation after asphyxial or fibrillatory cardiac arrest was compared using a porcine model. Asphyxial arrest: 7 animals received 45 micrograms/kg epinephrine, 7 animals 2.5 mg/kg dopamine, the remaining 7 animals received no drug treatment. All 7 animals given epinephrine could be resuscitated after 174 +/- 53 s, spontaneous circulation could be restored in only 3 of 7 animals given dopamine after 487 +/- 63 s and in none of the control animals could spontaneous circulation be established. Ventricular fibrillation: 7 animals were defibrillated without either mechanical measures or drug therapy. The following doses were given before defibrillation and after starting mechanical measures to separate groups of 7 animals each: 45 micrograms/kg epinephrine, 2.5 mg/kg dopamine, or no drug therapy. In the absence of either drug or mechanical measures and with mechanical measures only, spontaneous circulation could not be established in any of the cases. After administration of epinephrine, defibrillation and restoration of spontaneous circulation was achieved in 6 of 7 animals in 667 +/- 216 s, with dopamine, all the animals could be successfully resuscitated in the shorter time of 174 +/- 85 s. Epinephrine was found to be superior to dopamine in the treatment of asphyxial arrest whereas dopamine was found to be better in the management of ventricular fibrillation, probably by improving the balance between myocardial oxygen supply and demand.

Animals↗
PubMed1989

Endobronchial administration of emergency drugs.

Endobronchial emergency drug therapy is reviewed. Although intravenous drug administration is always preferable endobronchial application is a comparatively safe alternative when venous access is not available because an endotracheal tube is usually inserted during CPR. The optimal procedure remains to be clarified, however. Drugs and dosages currently being recommended for endobronchial use are described. With the reservations mentioned above the following recommendations can be made for the endobronchial administration of drugs to adult emergency patients: (1) Endobronchial administration of drugs is indicated in cases of cardiac arrest when an initial examination after the start of mechanical measures suggests that intravenous application will be difficult. This is also the case for emergency patients without cardiac arrest who are already intubated, and for whom the immediate administration of emergency drugs, such as lidocaine or atropine, is urgent and for whom venous injection cannot be carried out or cannot be carried out sufficiently quickly. We cannot at present share the view that the primary endobronchial administration of epinephrine is to be regarded as the treatment of first choice in every case of asystolic cardiac arrest (J. Schüttler et al., Anästh. Intensiwther. Notfallmed., 22 (1987) 63), as in most cases peripheral venous access can readily be established, thus avoiding the possible disadvantages of endobronchial administration (prolonged tachycardia, hypertension, arrhythmia from the depot effect, and also additional impairment of the pulmonary gas exchange). However, the washing-in of the administered drug is important after peripheral venous administration. (2) For adults, the present recommendation for the i.v. administration of epinephrine during resuscitation is 0.5-1 mg (7.5-15 micrograms/kg). Animal experiments show that under stable circulatory conditions ten times as much epinephrine must be administered endobronchially as intravenously in order to produce comparable pharmacodynamic effects or plasma levels. During resuscitation the corresponding value is approximately five times. Nevertheless, because of the dangers from the depot effect, an endobronchial dosage of 2-3 mg should not at present be exceeded. The best method probably consists of a combination of an initial restricted endobronchial dose with, if necessary, a further dose through a venous site which has been established in the interim. This recommendation seems to be reasonable because, as described, there are no exact data on the optimal dosage for epinephrine, even for i.v. administration (3) In the presence of a stable circulation the endobronchial dosag

Animals↗
PubMed1989

Comparison of epinephrine and norepinephrine in the treatment of asphyxial or fibrillatory cardiac arrest in a porcine model.

Many animal experiments have shown that alpha-receptor stimulation is a prerequisite for the improvement of myocardial perfusion during CPR. As there are no recent reports on the effectiveness of norepinephrine in the treatment of cardiac arrest, we investigated the effectiveness of epinephrine and norepinephrine after asphyxial or ventricular fibrillation cardiac arrest using a porcine model. After 3 min of asphyxial cardiac arrest, seven animals each received either 45 micrograms/kg epinephrine, 45 micrograms/kg norepinephrine, or placebo (controls). All drugs were given blind. All seven animals given epinephrine could be resuscitated after 174 +/- 53 sec, whereas six of seven given norepinephrine could be resuscitated after 473 +/- 116 sec. None of the seven given the placebo could be resuscitated. After 4 min of ventricular fibrillation cardiac arrest, none of the seven animals that received defibrillating countershocks at 4 min without either mechanical measures or drug therapy, and none of the seven that received CPR and countershocks but no drugs, could be resuscitated. In the group that received CPR plus 45 micrograms/kg epinephrine, defibrillation and restoration of spontaneous circulation were achieved in six of seven animals in 667 +/- 216 sec. In the group that received CPR plus 45 micrograms/kg norepinephrine, defibrillation and restoration of spontaneous circulation were achieved in all seven animals in the significantly shorter time of 86 +/- 18 sec. In this porcine model, norepinephrine appeared superior to the same dose of epinephrine in the treatment of ventricular fibrillation, with respect to resuscitation time.

Animals↗
PubMed1989

Early changes of intracranial pressure, perfusion pressure, and blood flow after acute head injury. Part 1: An experimental study of the underlying pathophysiology.

The present study examines intracranial pressure (ICP), cerebral perfusion pressure (CPP), and cerebral circulation immediately after experimental head injury in an animal model. The underlying systemic hemodynamic changes were also observed. To produce a standardized head injury, a fluid-percussion device was applied to the dura at the midline of 10 piglets. Seven other nontraumatized animals served as a control group. Hemodynamic parameters as well as ICP and CPP were recorded on-line, one value every 1.4 seconds. Cerebral blood flow (CBF) and cerebral vascular resistance (CVR) were measured three times using a microsphere technique. Immediately after head injury, the traumatized animals showed a sudden increase in ICP, with a maximum of 40 torr at 3 to 5 minutes, while there was a pronounced decrease in CPP from 85 to 40 torr. The CBF in the various brain areas fell from 55 to 22 ml/min/100 gm within 5 minutes after the impact, and CVR increased to 300% of control values within 90 minutes. The findings of this study demonstrated that cerebral circulation is critically jeopardized within a few minutes after trauma. This, in combination with a subsequent increase in CVR, makes the early development of ischemic brain damage very likely. In traumatized patients, treatment prior to hospital admission must therefore be directed at prevention of this fatal course.

Acute Disease↗
PubMed1989

[Control of the ultrafiltration rate as the main component of a new balancing system in continuous hemofiltration].

In 27 patients undergoing continuous pump-driven hemofiltration during intensive care, a new balancing device was used to control transmembrane pressure difference, and thus ultrafiltration rate, by means of an elastic reservoir and an infusion pump. The simultaneous infusion of substitution fluid by a second pump working independently of the former provided exactly and automatically the intended fluid balance. In only 0.7% of the total hemofiltration time (5519 h) could the preset ultrafiltration rate not be achieved. The simple components and installation of this device recommend its application in every intensive care unit that uses continuous arteriovenous or continuous pump-driven hemofiltration, relieving the staff and reducing unwanted and unnoticed deviations of intravascular volume and fluid balance.

Acute Kidney Injury↗
PubMed1989

[Lidocaine levels in the plasma following peripheral or central venous administration during cardiopulmonary resuscitation. Results of an experimental animal study].

A review of the literature indicates that the intravenous bolus dose of lidocaine should be reduced in all conditions where cardiac output is diminished. During external cardiac compression the cardiac output is only approximately 20-40% of the normal resting value. Various routes of drug administration are currently used during CPR. The routine use of a central venous line is not recommended as a first-line procedure for resuscitation. This route of administration is favored by some authors, however, because it is presumed to result in a more rapid onset of drug action and higher peak concentrations of the drugs used. The aim of this study was to determine the aortic plasma concentration of lidocaine after central venous as compared to peripheral venous administration under the conditions of external cardiac compression. Twelve pigs were allocated to two groups of 6 animals each using random numbers. Ventricular fibrillation was induced by applying an alternating current via two needle electrodes placed subcutaneously. Cardiac arrest was allowed to continue for a period of 1 min before mechanical measures were applied. Cardiac massage was carried out using a pneumatic piston device set to a compression rate of 80/min. Sixty seconds after mechanical CPR had been initiated, a bolus of 1.5 mg/kg lidocaine was given to 6 animals via a central venous line. The remaining 6 animals were treated with the same dose given into a vein of the earlobe. The 2% lidocaine solution was diluted to 20 ml with physiological saline in all animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗