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Biomedical subjects

G Hempelmann

Publications and source records attributed to G Hempelmann.

At least 487 records · Page 27Linked to original sources
PubMed1985

[Effect of an introductory dose of etomidate, methohexital and midazolam on adrenal cortex function before and after ACTH-stimulation].

The adrenocortical function after induction of anaesthesia using either etomidate, methohexital or midazolam was examined in 30 patients undergoing open heart surgery (ACVB). Midazolam and methohexital did not suppress the typical stress response assessed from the magnitude of the ACTH, cortisol and aldosterone levels. The ACTH-test was also normal. In contrast, induction of anaesthesia using etomidate led to a progressive fall in cortisol and aldosterone accompanied by an increase in ACTH. The ACTH-test resulted in only a minor increase in adrenocortical hormones. Thus an induction dose of etomidate, in contrast to methohexital and midazolam, markedly alters the normal function of the adrenal cortex. This side-effect of etomidate lasts for at least 4 hours but is no longer detectable after 24 hours.

Adrenal Cortex↗
PubMed1985

Intraoperative somatosensory evoked potentials as a prognostic factor of neurologic state after carotid endarterectomy.

Somatosensory evoked cervical and cortical potentials (SEP) were analyzed under general anesthesia in 106 patients undergoing carotid endarterectomy. Cortical electrical silence occurred in 5 patients without an inlying shunt; all developed a new neurologic deficit postoperatively. Analysis of the SEP in these patients revealed progredient cerebral ischemia as indicated by an increase in central conduction time (CCT) and a decrease in amplitude of the primary cortical response N20P25 resulting in a complete loss of cortical SEP later on during the clamping period. In 6 patients the insertion of a shunt restored the deteriorated SEP, these patients and those with unchanged SEP after carotid clamping showed an uneventful postoperative recovery. Taking the presence or absence of N20P25 as the sole parameter, the sensitivity of this technique was 83%, specificity 99% and predictability 83%. A normal range for CCT and amplitude of N20P25 during anesthesia and criteria for shunt insertion were developed. The presented monitoring regimen appears to be rational and is based on current concepts of cerebrovascular physiology and pathophysiology.

Adult↗
PubMed1985

Influence of nimodipine on cardiovascular parameters during coronary surgery.

A total of 78 patients about to undergo open-heart surgery (ACVB) were given nimodipine, a new calcium antagonist, in different doses (0.5 or 1.0 microgram/kg body weight min or 0.03/0.06 mg/kg h) before and during extracorporeal circulation. During infusion (10 to 40 min), the hemodynamic parameters were recorded, including intrapulmonary pressures, the cardiac output and the left ventricular contractility parameters LVP and dp/dtmax. The administration of nimodipine resulted in a dose-dependent reduction of the pulmonary and peripheral vascular resistance with a subsequent decrease of the mean arterial pressure or perfusion pressure (during extracorporeal circulation). The left ventricular pressure (LVP) was reduced, whereas sometimes the cardiac output increased considerably. The contractility (dp/dtmax) was not impaired even by the high nimodipine dose. The heart rate, too, remained unaffected. The nimodipine dose of 0.5 microgram/kg min used in neurosurgery for therapy did not cause any clinically relevant decrease in blood pressure; at higher doses (greater than or equal to 1.0 microgram/kg min) an excessive fall of the diastolic pressure must be avoided in patients with severe (coronary) sclerosis, because a reduced perfusion of poorly vascularized myocardial regions can occur despite improved global perfusion.

Blood Pressure↗
PubMed1985

Haemodynamic effects of fenoterol for labour inhibition during spinal or epidural anaesthesia.

Haemodynamic investigations, partly using invasive monitoring, concerning interactions between the beta-mimetic effect of fenoterol and the alpha-sympathetic blockade of spinal or epidural anaesthesia were made in a total of 49 patients during pregnancy, during caesarean section and in non-pregnant women. Haemodynamic effects of fenoterol during regional anaesthesia were compared with those during general anaesthesia (n = 17). Epidural or spinal anaesthesia enhance vascular beta-mimetic reactions at the start of tocolysis, leading to a profound but short-lasting decrease in blood pressure. This initial hypotension is more pronounced after regional than after general anaesthesia.

Adult↗
PubMed1985

[Hemodynamic effects following bolus administration of different vasopressive agents for blood pressure stabilization during peridural anesthesia].

Vasopressors are often used to counteract hypotension induced by sympathetic blockade during epidural or spinal anaesthesia. This study contains data of invasive haemodynamic investigations following single-shot applications of different vasoconstrictor agents (Akrinor, etilefrine, ephedrin, norfenefrin, amezinium) during a combination of epidural block and controlled ventilation with oxygen and nitrous oxide. In a preceding dose finding study equipotent dosage of the substances used was confirmed. Usually bolus application of these vasopressors causes only a short-lasting circulatory stimulation, which does not cover the whole period of sympathetic blockade (exception: amezinium). Even small doses of drugs acting only upon alpha-receptors, may cause unwanted peripheral vasoconstriction and decrease of the already lowered cardiac output (example: norfenefrine). The rise of blood pressure after betamimetics may be delayed by an initial vascular beta 2 stimulation (example: etilefrine). In other sympathetic stimulants venoconstriction and therefore improvement of cardiac output by increase of preload takes place after an interval of some minutes to cardiac stimulation (example: ephedrin, Akrinor). Though the use of vasopressor agents during central blockade cannot be recommended in general, substances with alpha- as well as beta-stimulation should be preferred, if necessary. When using substances with short duration of action continuous infusion has to be taken into consideration.

2-Hydroxyphenethylamine↗
PubMed1985

[Influence of various premedication agents, inhalation anesthetics and adjuvants on anesthesia with an opioid, alfentanyl].

Alfentanil mask anaesthesia was performed in 63 patients undergoing termination of pregnancy or curettage. Three different types of premedication were used: a) pethidine, promethazine, and atropine; b) diazepam and atropine; c) atropine. The patients were ventilated either with nitrous oxide and oxygen or with halothane and oxygen. Halothane reduced the frequency of muscular rigidity (32%; N2O 75%), postoperative sickness, and vomiting (23%; N2O 50%). On the other hand, patients regained consciousness earlier if nitrous oxide was used. Premedication a) also reduced the frequency of nausea and emesis (21%; other premedications 63%).-Alfentanil intubation anaesthesia was performed in 52 patients undergoing laparoscopy. Premedication and inhalation anaesthetic varied as described above in the group with mask anaesthesia. Muscular rigidity did not occur, and nausea/emesis were rare events (8%). Halothane prolonged the recovery phase of consciousness and respiration. Premedication a) also resulted in respiratory depression.

Abortion, Induced↗
PubMed1985

[Significance of endocrine parameters of stress].

Thirty two male patients undergoing coronary bypass surgery were given low (group A, 0.01 mg/kg bw) and high dose (group B, 0.035 mg/kg bw) fentanyl anaesthesia. Haemodynamic and hormone responses were investigated from the beginning of anaesthesia until extracorporeal circulation (ECC) (group A: n = 16; group B: n = 16). Significant changes in haemodynamics occurred only in group A including an increase in heart rate (36%) and systolic arterial pressure (21%). Plasma vasopressin (ADH) levels rose significantly in both groups after the beginning or surgical procedure which was markedly less pronounced in patients with high fentanyl (group B). In group A (low dose) a second dose of fentanyl was given after sternotomy, which was followed by a significant decrease in ADH (80% from previous value). No significant variations could be demonstrated in plasma levels of cortisol, ACTH, and human growth hormone (HGH). The data stress the importance of plasma-vasopressin-levels in determining the endocrine stress response following trauma and operation. On the other hand there was a lack of correlation between trauma and pain and frequently reported patterns of the endocrine-metabolic stress response.

Adrenocorticotropic Hormone↗
PubMed1985

[Hemodynamic effects with intravenous infusion of nifedipine (Adalat) in cardiosurgical patients].

The haemodynamic effects of 0.35 micrograms/kg bw/min and 0.70 micrograms/kg bw/min nifedipine (Adalat) as an infusion have been studied in 64 patients undergoing aortocoronary bypass surgery. The measurements were performed at four different times: 1. before induction of anaesthesia, 2. after induction of anaesthesia, 3. before cannulation of the aorta, 4. during extracorporeal circulation (ECC). In a follow-up study haemodynamics were controlled in detail after weaning from ECC. Each group was compared to a control group having received 0.9% NaCl as placebo. Preoperative as well as intraoperative application of nifedipine led to a decrease in arterial pressure and total systemic resistance, whereas cardiac index showed an increase. Heart rate, central venous pressure, pulmonary artery and pulmonary capillary wedge pressure remained almost unchanged. No relevant effect on contractility could be seen. During ECC nifedipine led to a decrease in arterial perfusion pressure and oxygenator-volume, thus indicating arterial vasodilatation and venous pooling. The investigations after ECC demonstrated stabilisation in cardiac rhythm and myocardial function. In conclusion, dose-dependent haemodynamic changes after intravenous application of nifedipine indicate a reduction in myocardial oxygen demand without detrimental effects on myocardial performance.

Blood Pressure↗
PubMed1985

[Hemodynamic changes in infusion with nimodipine].

The haemodynamic effects of 0.03 mg/kg bwxh (approximately equal to 0.5 microgram/kg bwxmin) and 0.06 mg/kg bwxh (approximately equal to 1.0 microgram/kg bwxmin) nimodipine as an infusion has been studied in 64 patients undergoing aorto-coronary-bypass surgery. The measurements were performed at 4 different times: 1. before induction of anaesthesia, 2. after induction of anaesthesia, 3. before cannulation of the aorta, 4. during extracorporeal circulation (ECC). After ECC haemodynamics were controlled in detail as a follow-up study. Each group was compared to a control group having received 0.9% NaCl as placebo. Preoperative infusion of 0.03 mg/kg bwxh nimodipine caused no relevant influence on haemodynamics, whereas 0.06 mg/kg bwxh led to a decrease in arterial blood pressure, peripheral and pulmonary vascular resistance and to a simultaneous increase in cardiac index. Similar haemodynamic effects were registered intraoperatively with both dosages. There was no relevant influence on contractility. During ECC nimodipine led to a decrease in arterial perfusion pressure and oxygenator volume, thus indicating arterial vasodilation and venous pooling. After ECC the investigation revealed a stabilization in cardiac rhythm and myocardial function. With respect to haemodynamics 0.03 mg/kg bwxh nimodipine, a dosage being used in neurosurgery, can be classified as safe. When higher dosages are necessary continuous haemodynamic and cerebral monitoring are recommended in order to avoid a hazardous drop in arterial blood pressure with a consecutive decrease in myocardial and cerebral blood flow (steal phenomena) in spite of better global perfusion.

Anesthesia, General↗
PubMed1985

[Colloid osmotic pressure and extravascular lung water following extracorporeal circulation].

With regard to Starling's equation, two factors are important for fluid regulation in pulmonary tissue: colloid osmotic pressure (COP) and hydrostatic pressure (PCP). The purpose of the study was to evaluate the relationship between COP, COP-PCP-gradient and extravascular lung water (EVLW) immediately after extracorporeal circulation (ECC). 39 consenting patients undergoing elective aorto-coronary bypass surgery received 1000 ml washed erythrocytes (w.e.; cell saver) +400 ml fresh frozen plasma (FFP) after ECC. Additionally, group I (n = 15) received 300 ml albumin 20%, group II (n = 13) 500 ml plasmaexpander (3% HES 200/0.5) and group III (n = 11) no more volume. At three different times, measurement of EVLW was performed by using double-indicator-dilution technique with indocyanine green and a microprocessed lung water computer: 15 minutes after ECC (before infusion), 45 minutes after ECC (after infusion), five hours after ECC. Application of 20% albumin led to a significant increase in COP (+67%) which was less pronounced in group II (+40%) and group III (+41%). Simultaneously, the most pronounced increase in EVLW could be observed in group I (+25%) as well. Pulmonary gas exchange in group I was more compromised (PaO2 -72 mmHg) than in group II (-38 mmHg) and group III (-50 mmHg). No correlation between EVLW and COP-PCP-gradient could be observed. In spite of a significant elevation of COP by using 20% albumin solution, EVLW increased with subsequent deterioration of pulmonary gas exchange. The presented data demonstrate no advantage of albumin 20%; if volume substitution is necessary after ECC, low concentrated plasmaexpanders (up to 10 ml/kg b.w.) may be preferred for several reasons.

Blood Proteins↗
PubMed1985

[Effects of ventilation with various end expiratory pressures on extravascular lung water following extracorporeal circulation].

The influence of ventilation with different endexpiratory pressure (0, 5, 10 cm H2O) on extravascular lung water (EVLW) in the period immediately after extracorporeal circulation (ECC) was investigated in a total of 35 patients undergoing coronary artery bypass surgery. Lung water measurement was performed by using the thermal-green dye double indicator dilution technique with indocyanine green and a microprocessed lung water computer. Ventilation with a moderate PEEP-level (5 cm H2O) led to an intensive reduction in lung water content, whereas EVLW-reduction was less pronounced, when higher PEEP-level (10 cm H2O) was applied. No significant relationship to various hemodynamic parameters, especially pulmonary artery pressure (PAP), pulmonary capillary wedge pressure (PCWP) or pulmonary vascular resistance (PVR) could be seen.

Blood Pressure↗
PubMed1985

[Hygienic relations and stability of drugs in peridural long-term infusion with implanted or external pumps].

Implantable devices (implanted pump/implanted catheter and port) are recommended for continuous epidural application of opiates or local anaesthetics in order to reduce hygienic problems during long term epidural medication. No signs of contamination could be found during bacteriologic culture of residual volumes of 30 patients treated with epidural drug delivery systems and of samples collected during an in vitro investigation (incubation of filled external pump systems at body temperature/storage of syringes with a premixed solution of opiate and local anaesthetic for repeated epidural bolus application). As demonstrated in a case report prophylactic antibiotic coverage prior to implantation may be necessary in patients with a preexisting susceptibility to infection. The concentrations of morphine (radioimmuno-assay) and of bupivacaine (gas-solid chromatography) within the reservoir were stable during clinical therapy as well as during the in vitro experiments.

Abscess↗
PubMed1985

[Acid-base findings in the cerebrospinal fluid of premedicated patients].

Analysis of acid-base-metabolism in cerebrospinal fluid is not easy, because pO2, pCO2 and pH change already within a short time after sampling. Acid-base-values in CSF have been measured in 50 healthy patients within 20 seconds after withdrawal. Our results (pH 7.298 +/- 0.007; pCO2 46.94 +/- 4.84 mmHg; HCO3 22.78 +/- 2.15 mVal/l; BE-2.4 +/- 2.39 mVal/l; pO2 50.27 +/- 14.06 mmHg) demonstrate, that CSF is more acidic than often claimed. This is important, whenever possible precipitations by intrathecal injection of local anaesthetics are discussed.

Acid-Base Equilibrium↗
PubMed1985

[Experiences with a new EEG spectral analyzer in carotid surgery].

Spectral analysis with the compressed spectral array display (CSA) and calculation of spectral edge frequency (SEF) was performed in 43 cases undergoing endarterectomy of the carotid bifurcation. New neurologic deficit appeared in 2 patients (= 4.6%). One of them died postoperatively (= 2.3%), the other suffered from permanent paralysis of the hand. Another 9 patients showed loss of high frequency activity (= decrease in SEF) without a new deficit in the postoperative period. A significant EEG event was defined as a decrease in SEF after carotid cross clamping for at least 5 min. Fisher's exact probability test revealed a close correlation between these EEG events and neurologic outcome. The sensitivity of the test, which was calculated on true positive and false negative events, was 100%, the specificity, based on true negative and false positive events, was 76%. The predictability of the test, based on all EEG events, was 18%; respectively 40% when calculated on significant events.

Anesthesia↗