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Biomedical subjects

J Boldt

Publications and source records attributed to J Boldt.

321 records · Page 18Linked to original sources
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

[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

[Calcium antagonists in anesthesia. Additive analgesia using nimodipine in heart surgery].

Stress and pain induced by surgical trauma seem to be attenuated when calcium antagonists have been applied. In order to ascertain the effect of nimodipine, a new strong acting calcium channel blocker on plasma levels of various stress hormones twenty patients undergoing cardiovascular surgery where investigated in two groups. Ten patients received high-dose fentanyl anaesthesia (mean: 2,45 mg fentanyl/patient), whereas another ten patients were treated with 0,1 mg fentanyl/patient in addition to nimodipine 1,0 micrograms/kgbw X min (from onset of anaesthesia until start of extracorporeal circulation). Between the two groups were no significant differences with respect to perioperative course and postoperative demand for analgetics. Plasma levels of ACTH, somatotropin, glucose and free glycerol were markedly elevated in all patients (n = 20) intra- and postoperatively, whereas cortisol and prolactin remained unchanged. The present data suggest an additive analgesic effect of nimodipine during surgery. This phenomenon is possibly due to a blocking effect of calcium channel blockers on nociceptive nerves. The present model assumes that calcium is essential in pain perception and that decreased calcium would result in analgesia.

Analgesia↗
PubMed1984

[Plasma level of lidocaine following intraoperative bolus injection and infusion in heart failure].

In two groups of ten patients each (group I: myocardial insufficiency, group II: no myocardial insufficiency) during anaesthesia arterial plasma levels of lidocaine were studied, following iv bolus administration (1 mg./kg. bw) and subsequent lidocaine infusion (2 mg./min.) for 15 minutes. With this dosage, recommended for antiarrhythmic therapy, plasma levels exceeded the therapeutic range in group I and in some patients reached almost toxic levels (10 micrograms./ml.). In group II lidocaine plasma levels were within the therapeutic range (1,5-4 micrograms./ml.). In patients with myocardial insufficiency and/or reduced hepatic metabolism antiarrhythmic therapy with lidocaine has to be performed with significantly reduced dosages; drug monitoring is recommended.

Arrhythmias, Cardiac↗
PubMed1984

[Effect of postoperative parenteral feeding on protein metabolism in heart surgery patients. A comparative study].

To investigate the importance of amino acid infusions in immediate postoperative parenteral nutrition, cardiac patients were randomly allocated into two groups. Applicating identical carbohydrate calories (2000 kcal/day) group 1 received only essential amino acids while in group 2 a combined pattern of essential and non essential amino acids was infused. In addition to routine laboratory data several parameters of protein metabolism including nitrogen balance were evaluated. Although nitrogen balance was positive only in group 2 the differences between the two groups concerning other parameters measured were minimal. The different infusion regimes are discussed revealing the significance of additional parenteral nutrition in these patients.

Amino Acids↗
PubMedDate not supplied

Effect of O6-alkylguanine-DNA alkyltransferase on the frequency and spectrum of mutations induced by N-methyl-N'-nitro-N-nitrosoguanidine in the HPRT gene of diploid human fibroblasts.

N-Methyl-N'-nitro-N-nitrosoguanidine (MNNG) reacts with 12 nucleophilic sites in DNA to induce a variety of lesions, but O6-methylguanine (O6-MeG) and O4-methylthymine are the most effective premutagenic lesions produced, mispairing with thymine and guanine, respectively. O6-MeG is repaired by O6-alkylguanine-DNA alkyltransferase (AGT), which removes the methyl group from the O6 position and transfers it to itself, rendering the transferase inactive. When diploid human fibroblasts were exposed to 25 microM, O6-benzylguanine (O6-BzG) in the medium for 3 h, their level of AGT activity was dramatically reduced, to a level of at most 1.6% of the control. Populations of cells pretreated with this level of O6-BzG for 2 h or not pretreated, were exposed to MNNG at a concentration of 2, 4 or 6 microM in the presence or absence of O6-BzG and assayed for survival of colony-forming ability and the frequency of 6-thioguanine-resistant cells (mutations induced in the HPRT gene). O6-BzG (25 microM) was also present in the appropriate half of the cells during the 24 h immediately following exposure to MNNG. This 27-h exposure to O6-BzG alone had no cytotoxic or mutagenic effect on the cells but significantly increased the cytotoxicity and mutagenicity of MNNG, increasing the mutant frequency to that found previously in human cells constitutively devoid of AGT activity. At doses of 2 microM and 4 microM MNNG, the mutant frequency observed with the AGT-depleted cells was 120 x 10(-6) and 240 x 10(-6), respectively; in the cells with abundant AGT activity, these values were 10 x 10(-6) and 20 x 10(-6), respectively. DNA-sequence analysis of the coding region of the HPRT gene in 36 independent mutants obtained from MNNG-treated AGT-depleted populations and 36 from the control populations showed that even though AGT repair lowered the frequency of mutants by more than 90%, it did not affect the kinds of mutations induced by MNNG nor the strand distribution of the premutagenic guanine lesions. In mutants from the AGT-depleted cells, there were 26 base substitutions and 13 putative splice site mutations; in the control, there were 25 base substitutions and 11 splice site mutations. All but two substitutions involved G.C with 92% being G.C----A.T. In both sets, approximately 73% of the premutagenic lesions were located in the nontranscribed strand.(ABSTRACT TRUNCATED AT 400 WORDS)

Base Sequence↗
PubMedDate not supplied

Unexpected return of spontaneous circulation after cessation of resuscitation (Lazarus phenomenon)

Since 1982, more than 20 patients with return of spontaneous circulation after cessation of cardiopulmonary resuscitation (Lazarus phenomenon) have been published. We report on another case here. Such cases are probably underreported due to medicolegal concerns. After cessation of resuscitation, each patient should be further monitored for at least 10 min to detect a possible Lazarus phenomenon.

Aged↗
PubMedDate not supplied

Anesthesia in pediatric heart transplantation.

Heart transplantation is a widely accepted therapy for end-stage myocardial failure in adults. However, few centers have experience in the treatment of newborns and children. The management of these children from the anesthesiologic viewpoint is demonstrated in our first 10 patients. Ages ranged from 5 days to 5 years; weights ranged from 2900 gm to 16 kg. The children suffered from hypoplastic left heart syndrome (n = 5) or cardiomyopathy (n = 5). Eight patients had to receive catecholamines (dobutamine) before surgery. In neonates cardiopulmonary bypass (CPB) with hypothermic cardiac arrest at 18 degrees C was used; in the older children continuous CPB at 24 degrees to 28 degrees C was performed. Inotropic support during and after weaning from CPB was necessary in all patients who received dobutamine (range, 2 to 10 micrograms/kg/min), epinephrine (range, 0.03 to 1.0 microgram/kg/min), or both. The phosphodiesterase inhibitor enoximone (1.0 mg/kg) was administered to five patients. Prostaglandin E1 was given to four patients, and it was necessary to give additional tolazoline to two patients. Heart transplantation is a challenge for anesthesiologists during the prebypass period as well as during the weaning and early postbypass periods. More experience is necessary to optimize the anesthetic management of these children.

Alprostadil↗
PubMedDate not supplied

Enhancement of myocardial energy potentials in man by glucose-insulin treatment before and after ischaemic heart arrest.

Thirty-six patients undergoing aortic valve replacement were investigated to ascertain whether the addition of glucose-insulin before and after ischaemic heart arrest could aid to the functional recovery of hearts following global ischaemia. One group of patients (n = 14) received glucose plus insulin from the onset of anaesthesia until crossclamping of the aorta (1 g + 1.5 U/kg bw X h). A second dose (0.5 g + 1.0 U/kg bw) was given at the end of ischaemia. 22 patients, serving as control received glucose in the same manner but without insulin. Needle biopsies from the left ventricular apex region were obtained: before starting cardiopulmonary bypass; at the end of ischaemia; and after 10 minutes of reperfusion and analyzed for its content of ATP, CP ADP and lactate. In both groups ATP and CP were significantly decreased after ischaemia and increased after reperfusion. ADP and lactate levels were elevated after ischaemia and decreased after reperfusion in the insulin-group but not in the control-group. During the total investigation period ATP- and CP-concentrations in the insulin-group were higher compared to the control-group, whereas ADP and lactate of the control-group were above the insulin-group.

Adenosine Diphosphate↗