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Biomedical subjects

O Werner

Publications and source records attributed to O Werner.

At least 73 records · Page 4Linked to original sources
PubMed1991

Effects of thoracic epidural anesthesia and adrenoceptor blockade on the cardiovascular response to dopamine in the dog.

The cardiovascular effects of dopamine are different before and during thoracic epidural anesthesia (TEA). To evaluate underlying adrenoceptor-mediated mechanisms, dopamine effects were investigated in nine chloralose-anesthetized dogs. The circulatory response to dopamine (0-40 micrograms.kg-1.min-1) was studied before and during TEA, and during TEA after introducing the alpha 1-antagonist prazosin (0.3 mg.kg-1), the alpha 2-antagonist rauwolscine (0.3 mg.kg-1), and the beta 1-antagonist metoprolol (0.5 mg.kg-1). TEA decreased mean arterial pressure (MAP) by 29%, cardiac output (CO) by 36%, heart rate (HR) by 27%, and the maximum rate of change of left ventricular pressure (LVdP/dt) by 52%. Systemic vascular resistance, pulmonary vascular resistance and mean pulmonary artery pressure (MPAP) remained unaltered by TEA. Dopamine-induced increases in MAP and HR were augmented by TEA. Both MAP and LVdP/dt increased above pre-TEA levels at 10 micrograms.kg-1.min-1. Prazosin attenuated the increases in MAP and MPAP by dopamine. Adding rauwolscine almost abolished the dopamine response in MAP and MPAP. Metoprolol almost eliminated the dopamine effects on CO and LVdP/dt. Only minor alterations in cardiac filling pressures were observed during the study. Plasma norepinephrine (NE) concentration was lower during than before TEA at corresponding dopamine infusion rates. NE was reduced by the beta 1-blockade. During TEA, the plasma dopamine levels were generally higher, and they were further increased by adding beta 1-blockade. In conclusion, myocardial contractility and arterial pressure were restored to pre-TEA values by dopamine at 5-10 micrograms.kg-1.min-1.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic alpha-Antagonists↗
PubMed1991

Hemodilution during bone marrow harvesting in children.

Eight children (1-17 yr) underwent bone marrow harvesting while in cytostatic-induced remission of their disease (leukemia [n = 6], Ewing sarcoma, and non-Hodgkin lymphoma). After the induction of general anesthesia, all patients were loaded with 10 mL/kg of a 6% high-molecular dextran solution (Macrodex--Pharmacia), which resulted in a significant preoperative decrease in hematocrit (Hct) from 32% +/- 6% to 28% +/- 5% (hypervolemic hemodilution) and also allowed the procedure to be performed without systemic heparinization. The blood aspirated during the harvest (24 +/- 6 mL/kg; mean +/- SD) was replaced with a solution of 6% dextran and Ringer's acetate solution, and the Hct decreased from 28% +/- 5% to a minimum of 18% +/- 3%. Immediately after the harvest, 10 mL/kg of homologous packed red blood cells was transfused, increasing Hct to 25% +/- 3%. Oxygen saturation in the superior caval vein (ScvO2) decreased from 79% +/- 4% before the harvest to 70% +/- 3% (P less than 0.01) at the end of it, and then increased to 74% +/- 3% after the transfusion of homologous packed red blood cells. There was a strong linear correlation between mean values for Hct and ScvO2 during the various stages (r = 0.99). Mean heart rate decreased gradually during the procedure, from 106 +/- 10 to 86 +/- 7 beats/min. There was no significant change in arterial pressure, but cardiac output measured by impedance cardiography was about 30% greater during harvesting than during undisturbed anesthesia. Pulse oximetric saturation was 99% or 100% throughout. Caval venous blood lactate and pyruvate concentrations remained within normal limits in all children.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1990

Dopamine counteracts hypertension during general anesthesia and hypotension during combined thoracic epidural anesthesia for abdominal aortic surgery.

The influence of the degree of sympathetic nervous system activation on the cardiovascular effects of dopamine was studied during abdominal aortic surgery in 13 patients. The arterial plasma norepinephrine concentration (NE) was used as an index of sympathetic nervous system activity. During anesthesia with nitrous oxide and fentanyl, 7 patients (group 1) had a NE above 700 pg/mL and an increased mean arterial pressure (MAP) compared with the preanesthetic level (150 +/- 6 v 117 +/- 10 mm Hg; p less than 0.01, mean +/- SEM). The other 6 patients (group 2) had no significant change in MAP compared with the preanesthetic MAP (119 +/- 7 v 105 +/- 4 mm Hg). Dopamine, 4 micrograms/kg/min, decreased MAP in group 1 by 19% (150 +/- 6 to 121 +/- 8 mm Hg; P less than 0.05) because of a 32% +/- 9% decrease (P less than 0.05) in systemic vascular resistance. MAP was not altered by dopamine in group 2 (119 +/- 7 v 123 +/- 6 mm Hg; not significant). Following termination of dopamine, the anesthetic was supplemented with thoracic epidural anesthesia (TEA). This reduced MAP to 65 +/- 7 mm Hg (P less than 0.01) and 56 +/- 3 mm Hg (P less than 0.01), and NE to 441 +/- 76 (P less than 0.05) and 235 +/- 45 pg/mL (P less than 0.05) in groups 1 and 2, respectively. During TEA, dopamine increased MAP similarly in both groups, to 85 +/- 7 mm Hg (P less than 0.01) and 82 +/- 9 mm Hg (P less than 0.05), respectively. In conclusion, dopamine, at the same dosages, counteracted hypertension during general anesthesia and counteracted hypotension during general anesthesia combined with TEA.

Analysis of Variance↗
PubMed1990

Functional residual capacity in anesthetized children: normal values and values in children with cardiac anomalies.

To assess the increase in functional residual capacity (FRC) with growth, FRC was measured after induction of anesthesia in two groups of children. One group consisted of 74 children, 0.1-11.2 yr of age, without signs of cardiorespiratory disease (referred to here as "normal" children), and the other of 21 children, 0.2-6.9 yr of age, with cardiac malformations. Anesthesia was maintained with halothane in the normal children and with fentanyl, droperidol, and nitrous oxide in the children with cardiac anomalies. All patients were paralyzed, their tracheas intubated, and their lungs mechanically ventilated. FRC was measured with an automated tracer gas washout technique. In 70 patients the measurements were performed in duplicate with a mean coefficient of variation of 2.0%. FRC correlated significantly with height, weight, and age in both groups. Multiple regression analysis for both groups considered together indicated no significant improvement when factors for the sex of the child or for the presence of cardiac anomalies were incorporated into the model. In normal children the simple linear and nonlinear regression equations for FRC (in milliliters) versus height (in centimeters) were: FRC = -529 + 9.48 x height, r = 0.96; and FRC = 0.00175 x height2.66, r = 0.97, respectively. The corresponding equations for FRC (in milliliters) versus weight (in kilograms) were: FRC = -92 + 29.9 x weight, r = 0.93; and FRC = 9.51 x weight1.31, r = 0.95.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1990

Mechanical ventilation during low-flow anaesthesia. Experience with an alternative to the bag-in-bottle.

Clinical experience with low-flow anaesthesia during controlled ventilation of the lungs is described. The anaesthesia circle is separated by a corrugated hose that serves as a large deadspace. This open connexion has no bellows or overflow valve and therefore the risk of mechanical dysfunction is small. No mixing of circle and ventilator gas occurs during normal operation. Major decreases in the oxygen concentration in the system are unlikely even if the fresh gas flow is interrupted or significant leaks from the circle occur because 100% oxygen is delivered by the ventilator. A hose volume larger than 1650 ml prevented gas mixing at tidal volumes of 380-1170 ml. There was no system-related mishap in over 600 patients, who comprised about 40% of the neurosurgical patients anaesthetised during that period. The cost of isoflurane was reduced to about 33% of that incurred during previous periods.

Anesthesia, General↗
PubMed1990

Intestinal hemodynamics during laparotomy: effects of thoracic epidural anesthesia and dopamine in humans.

The effects of thoracic epidural anesthesia (TEA) and dopamine infusion (4 micrograms.kg-1.min-1) on superior mesenteric artery blood flow (SMABF), the mesenteric arteriovenous oxygen difference (AVDO2), and the mesenteric venous lactate concentration were studied in nine patients before abdominal aortic reconstruction. Thoracic epidural anesthesia reduced SMABF, as measured by electromagnetic flowmetry, to 77% +/- 8% (mean +/- SEM) of control (P less than 0.05), and mean arterial pressure to 46% +/- 4% of control (P less than 0.01). The mesenteric AVDO2 increased from 27 +/- 3 to 39 +/- 6 mL/L (P less than 0.05) and superior mesenteric venous lactate from 1.03 +/- 0.11 to 1.60 +/- 0.38 mmol/kg (P less than 0.05); systemic AVDO2 and lactate did not change. Dopamine had no significant effect on SMABF and mean arterial pressure before TEA. However, dopamine increased SMABF during TEA (from 77% +/- 8% to 137% +/- 21% of control; P less than 0.01), returned mesenteric AVDO2 to 27 +/- 3 mL/L (P less than 0.05), and elevated mean arterial pressure to 62% +/- 4% of control (P less than 0.05). It is concluded that the decrease in perfusion pressure during TEA reduces SMABF with resultant evidence of intestinal reductive metabolism. The intestinal blood flow during TEA was improved by dopamine.

Aged↗
PubMed1990

[Tumor histogenesis and macrophage content in lymphomas in Marek's disease of chickens].

Histological and to some extent additional enzyme-histochemical studies were conducted into 28 cases of Marek's disease with minor, moderate, and intensive lymphoma formation. The investigations were undertaken with a view to differentiating T-lymphocytes and macrophages by differentiated activity on acid unspecific alpha naphthylacetate esterase. Lymphoma specimens were cytologically evaluated under semi-quantitative or quantitative aspects. Evidence was provided to the existence of correlations between intensity of Marek's disease lymphomas and their relative contribution to lymphocytes, lymphoblasts, and macrophages. The amount of lymphoblasts was found to go up along with advancing lymphoma proliferation, while the amounts of lymphocytes and macrophages went down. Moderately pronounced lymphomas contained 16 percent macrophages on average, whereas only about 8 percent were recordable from highly pronounced lymphomas. The high presence of macrophages in less developed lymphomas is considered to reflect unspecific defence reaction against neoplastic lymphatic cells in the phase of low tumour malignancy.

Animals↗
PubMed1989

Lung function in the supine and lateral decubitus positions in anaesthetized infants and children.

We have measured dynamic lung compliance or static lung thorax compliance, functional residual capacity (FRC), and two indices of pulmonary gas mixing (pulmonary clearance delay (PCD) and single breath alveolar mixing efficiency (SBAME)) in 25 children in the supine and lateral decubitus position during nitrous oxide-halothane anaesthesia. Fifteen children (5 month-8 yr) breathed spontaneously and 10 (4 month-9 yr) underwent mechanical ventilation. Tidal volume and rate of ventilation were, respectively, 3.5-6.6 ml kg-1 and 22-46 b.p.m. in spontaneously breathing supine children, and 8.3-15 ml kg-1 and 20-30 b.p.m. in mechanically ventilated supine children, and did not differ significantly in the lateral position. There was no significant change in compliance when the child was turned to the lateral position, but FRC increased from 22 (SD7) to 25 (8) ml kg-1 (P less than 0.01) in the spontaneously breathing group and from 19 (6) to 24 (8) ml kg-1 (P less than 0.01) in the other group. In spontaneously breathing children, PCD and SBAME indicated a somewhat impaired pulmonary gas mixing (P less than 0.05) after the child had been turned to the lateral position, but no change occurred in the other group. These findings suggest that the distribution of ventilation in anaesthetized children in the lateral position is similar to that reported previously in anaesthetized adults.

Anesthesia↗
PubMed1989

Effects of lung surgery and one-lung ventilation on pulmonary arterial pressure, venous admixture and immediate postoperative lung function.

We studied 17 patients, with unilateral lesions in lung or thoracic wall, during thoracotomy performed in the full lateral position. Balanced anaesthesia was used with pethidine and 50% nitrous oxide, in oxygen. The procedure included a period of one-lung ventilation (OLV). Haemodynamic and gas exchange measurements were performed before and after pleurotomy, during OLV, after re-expansion of the lung and after closure of the thoracic wall. The function of each lung was assessed separately during the first and last stages. Mean venous admixture was 9-12% before and after OLV and 31% during OLV. There was a positive correlation between venous admixture and pulmonary arterial pressure during OLV. End-tidal PCO2, carbon dioxide elimination and compliance of the operated side were reduced significantly at the end of the procedure; this is consistent with reduced blood flow and increased water content in that lung.

Anesthesia, General↗
PubMed1989

Thiopental requirements for induction of anesthesia in neonates and in infants one to six months of age.

The authors determined the thiopental dose needed for satisfactory induction in ten neonates, 0-14 days of age, and 20 infants, 1-6 months of age. A single iv bolus of thiopental was given. Thirty seconds after injection the anesthesia mask was applied and the response was observed during the following 30 s while the patient breathed oxygen. Induction was considered satisfactory if there were no gross movements or coughing. The dose required for satisfactory induction in 50% of patients, ED50 (+/- SE), was 3.4 +/- 0.2 mg/kg in neonates and 6.3 +/- 0.7 mg/kg in infants (P less than 0.001). It is concluded that the thiopental dose needed for satisfactory induction is less in neonates than in infants.

Anesthesia, Intravenous↗
PubMed1989

Effects of dopamine on intestinal hemodynamics and motility during epidural analgesia in the cat.

The effects of dopamine on intestinal blood flow (IBF) and intestinal contraction rate (ICR), and on mean arterial pressure (MAP) and heart rate (HR) were studied in eight cats before and during epidural analgesia (EDA). Before EDA, dopamine 5 and 10 micrograms.kg-1.min-1 had no effect on IBF, MAP and HR, but the higher infusion rate decreased ICR by 71 +/- 19% (mean +/- 1 s.e.mean) (P less than 0.01). EDA significantly increased IBF when intestinal arterial pressure was maintained at an unchanged level by means of a pump, and transiently increased ICR and intestinal tone, but reduced MAP by 46 +/- 8% (139 +/- 11 to 75 +/- 9 mmHg, P less than 0.01) and HR by 26 +/- 3% (248 +/- 7 to 184 +/- 8 beats.min-1, P less than 0.01). During EDA, dopamine increased IBF further, the response being similar at both infusion rates. 5 micrograms.kg-1.min-1 increased HR by 26 +/- 7 beats.min-1 (P less than 0.01) and MAP by 19 +/- 9 mmHg (ns). The corresponding values at 10 micrograms.kg-1.min-1 were 65 +/- 14 beats.min-1 (P less than 0.01) and 35 +/- 8 mmHg (P less than 0.01), respectively, Vascular autoregulation appeared to be unaffected by dopamine and EDA. The effect of dopamine on ICR was not significantly different to what was seen before EDA. It is concluded that the effects of dopamine on IBF, MAP and HR were markedly different during EDA as compared to before the block and that ICR was reduced by dopamine, while it was transiently increased by EDA.(ABSTRACT TRUNCATED AT 250 WORDS)

Analgesia, Epidural↗
PubMed1989

A reflection filter for isoflurane and other anaesthetic vapours.

A new way of saving anaesthetic vapours is described. The method is analogous to the heat-moisture exchanger principle: the vapour is trapped in a filter during expiration and is returned to the patient during the subsequent inspiration. Fresh vapour is supplied on the patient side of the filter. A small container with 60 ml of a hydrophobic zeolite (an inorganic material) was used as filter. In model lung tests, this reduced the isoflurane consumption by 51% at a tidal volume of 300 ml, by 57% at 600 ml and by 51% at 930 ml. Neither isoflurane nor halothane yielded any degradation products when brought in contact with the zeolite.

Anesthesia, Closed-Circuit↗
PubMed1988

When asleep, one is cooler on beta-blockade than on placebo. A study of pulmonary arterial blood temperature and skeletal muscle heat production in anaesthetized man.

The effect of beta 1-adrenergic blockade on body temperature was studied during general anaesthesia by means of a thermistor in an indwelling pulmonary arterial catheter. Metoprolol (200 mg daily) or placebo was given double-blind preoperatively for at least 2 weeks to 27 hypertensive patients undergoing abdominal surgery. A significantly greater temperature fall was observed in the metoprolol group compared with the placebo group. Heat production in the rectus abdominis muscle, measured by direct microcalorimetry, was significantly lower after metoprolol. The hypothermic effect of beta-adrenergic blockade during anaesthesia deserves special attention.

Adult↗
PubMed1988

Ventilation inhomogeneity during controlled ventilation. Which index should be used?

Six indexes for diagnosing uneven ventilation by tracer gas washout were studied. The indexes were lung clearance index, mixing ratio, Becklake index, multiple-breath alveolar mixing inefficiency, moment ratio, and pulmonary clearance delay, all of which increase with impaired pulmonary gas mixing. In model lung tests, indexes that compared the actual washout curve with a calculated ideal curve (mixing ratio, multiple-breath alveolar mixing inefficiency, and pulmonary clearance delay) were unaffected by changes in tidal volume and series dead space, whereas the others varied markedly. In both spontaneously breathing and mechanically ventilated patients all indexes showed a significant difference between smokers and nonsmokers (P less than 0.002), but the indexes were somewhat different in their assessment of different ventilatory patterns. However, the mean value for all indexes, with the exception of mixing ratio, was smallest with a fast insufflation followed by an end-inspiratory pause. Any of the indexes may be useful if its limitations are recognized, but mixing ratio, multiple-breath alveolar mixing inefficiency, and pulmonary clearance delay seem preferable, because they are not affected by changes in tidal volume and dead space fraction.

Adult↗
PubMed1987

Ventilatory consequences of the lateral position and thoracotomy in children.

Functional residual capacity (FRC), breath-by-breath compliance of the respiratory system (Crs) and arterial oxygen tension (PaO2) were measured in ten children, two months to nine years of age, during anaesthesia for surgical correction of patent ductus arteriosus or coarctation of the aorta. The children were mechanically ventilated with halothane, nitrous oxide and oxygen. FIO2 was kept constant in each child. After induction of anaesthesia, FRC was 17 +/- 7 ml X kg-1 (mean +/- 1 SD), corresponding to 60 +/- 22 per cent of a predicted awake value. FRC increased to 21 +/- 8 ml X kg-1 (p = 0.0005) when the child was turned to its right side and decreased to 13 +/- 5 ml X kg-1 (p = 0.0003) when the pleura was opened. No significant change in Crs or PaO2 occurred during these manoeuvres. Retraction of the upper lung to visualize the great vessels caused a significant decrease in FRC, Crs, and PaO2. The lowest PaO2 observed during this stage was 70.0 mmHg. After surgery FRC and PaO2 were about the same as before surgery while Crs had decreased from 0.87 +/- 0.18 preoperatively to 0.64 +/- 0.15 ml X cmH2O-1 X kg-1 (p = 0.0069). This study shows that FRC increases when mechanically ventilated children are placed in the lateral position, and that thoracotomy is associated with marked changes in FRC, Crs and PaO2.

Child↗