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W Wilhelm

Publications and source records attributed to W Wilhelm.

At least 19 recordsLinked to original sources
PubMed1996

[Desflurane and isoflurane. A comparison of recovery and circulatory parameters in surgical interventions].

OBJECTIVES: The new volatile anaesthetic desflurane is characterized by very low blood-gas and tissue-blood partition coefficients, so that rapid induction of anaesthesia and shorter recovery times can be expected. The aim of this investigation was to compare the effects of desflurane and isoflurane on haemodynamics and recovery time when used as part of a balanced anaesthesia technique for elective surgery. METHODS: Fifty patients (18 years and older, ASA status I-III) scheduled for elective surgery (no laparoscopies) of at least 60 min duration were included in this open, randomised, phase-III clinical trial. After oral premedication with midazolam 7.5 mg 45 min before transfer to theatre, anaesthesia was induced with fentanyl 0.1 mg and thiopental 5 mg/kg; succinylcholine or vecuronium facilitated intubation. Desflurane and isoflurane, respectively, were used for maintenance of anaesthesia, both in 50% N2O, with the inspired concentration adapted to the degree of stimulation. All patients were ventilated in a semi-closed system; muscle relaxation was achieved with vecuronium. The electrocardiogram, heart rate (HR), and direct arterial blood pressure (BP) were recorded continuously and anaesthetic gas detection was performed by an infrared absorption technique. With termination of surgery the volatile anaesthetic was discontinued and the following emergence times recorded: spontaneous ventilation (VT > 300 ml), extubation, eye opening, correctly answering the date of birth, arrival in and possible discharge from the post-anaesthesia care unit (PACU). RESULTS: In all, 49 patients were studied at random (desflurane n = 24, isoflurane n = 25). Data of demographics and anaesthetic technique were comparable in both groups (Tables 2 and 3). Anaesthetic elimination (expressed as FA/FAO) was significantly more rapid in the desflurane group 3 min after termination of anaesthesia (Fig. 1). Comparing the emergence times, there was no significant difference between desflurane and isoflurane: in both groups patients opened their eyes 12 min (median time) after termination of the operation (Table 4). Haemodynamics (HR, systolic and diastolic BP) were comparable at intubation, skin incision, end of surgery, extubation, and in the PACU (Fig. 2a, b). In 2 patients a rapid increase in the inspired concentration of desflurane during induction of anaesthesia produced a profound sympathoadrenergic reaction with an excessive increase in BP and HR. Similar reactions in other patients did not occur when the inspired concentration of desflurance was slowly increased. CONCLUSIONS: Despite the physicochemical properties of the new agent, emergence times were similar for desflurane and isoflurane in our study. These results, which are in contrast to those of some other authors, are most probably due to the study design, which included the use of premedicants (midazolam) and a low dose of fentanyl. The reported sympatho-adrenergic reactions after rapid changes in the inspired concentration of desflurane during induction of anaesthesia have been observed by others as well. It seems that this initial cardiovascular stimulation can be avoided by slow increases in desflurane concentration. In summary, desflurane compares to isoflurane in balanced anaesthesia for general surgical procedures with regard to haemodynamics, while the time to awakening is not necessarely reduced.

Adolescent↗
PubMed1996

[Accuracy of measurement and overestimation of CO2 of two capnometers intended for potential use in emergency medicine].

UNLABELLED: Capnometry, the noninvasive measurement of end-expiratory CO2 concentration (cCO2, vol%) or calculation of its respective partial pressure (pCO2; mmHg) is an established method. However, for prehospital settings, capnometry is still used very restrictively, mainly owing to the respective devices used. The prerequisite for their use is sufficient accuracy (+/-2 mmHg) and easy handling. Two special capnometers (STAT CAP. Nellcor: mainstream, semiquantitative estimation; Capnocheck 8200, BCI: sidestream, quantitative measurement, numeric display), developed recently for potential use in emergency medicine, are said to fit these criteria. Therefore, the objective of the present investigation was to assess the accuracy and precision of both devices, comparing methods under standardized in vitro (reference gases) and in vivo (intubated and ventilated patients) conditions. METHODS: Both devices ("STAT CAP": pCO2 range, light bars; "Capnocheck 8200") were evaluated regarding the accuracy of pCO2 (Capnocheck) and the precision of the CO2 range (STAT CAP). Tests were performed with four dry gas mixtures (STPD) of defined composition and during ventilation of 20 intubated patients (BTPS). All measurements were compared with the alveolar gas monitor "AGM 1304" (Brüel & Kjaer, Denmark) as a reference method with a proven +/- 1 mmHg accuracy of pCO2 measurement. RESULTS: The "Capnocheck" (BCI) presented an accuracy of the pregiven pCO2 of 0.7-1.4 mmHg (dry gas mixtures, STPD) and an overestimation of 0.2 +/- 4.1 mmHg (BTPS) during ventilation with pure oxygen; inaccuracy during ventilation with 70% N2O in O2 proved to be + 1.2 +/- 1.7 mmHg (BTPS). Nellcor's "STAT CAP" failed to reach the target value in 10% of analyses, as shown by the respective segment bar of the display. CONCLUSION: Evaluation of the accuracy of capnometers must focus on the necessary pH2O correction and the possible effects exercised by O2 (and N2O) as well as the possible dependence on barometric pressure (if pCO2, mmHg, is the desired value). The "Capnocheck" showed an accuracy of more than 2 mmHg in dry gas mixtures as well as in humidified air. Concerning the practical use during constant artificial ventilation, the digital display and accuracy of the sidestream capnometer allow for reliable conclusions on patients' ventilation and circulation (CO2 elimination). The 90% accuracy of the segment bar display of Nellcor's "STAT CAP", per se covering only a rather broad range of 20 mmHg, obviously does not provide more than a rough overview. Therefore, the STAT CAP cannot be recommended for prehospital capnometry in the field. However, both the accuracy of the BCI capnometer (Capnocheck) and its numeric display and easy handling strongly recommend this device also for clinical use.

Blood Gas Analysis↗
PubMed1996

[The effect of midazolam after intranasal administration on spontaneous respiration and respiratory control in young children].

AIM: The aim of this study was to investigate the influence of intranasally administered midazolam in different doses on spontaneous respiration in children. METHODS: 40 children received in randomised order 0.2, 0.4 or 0.6 mg/kg b.w. midazolam intranasally or NaCl 0.9% as control. 10 minutes later, anaesthesia was induced by inhalation of halothane, nitrous oxide and oxygen. The children were breathing spontaneously at a PEEP of 5 cm H2O on a circle system with a fresh gas flow of 61/min (FIO2 = 0.33). Intubation was performed in deep anaesthesia without muscle relaxant. Halothane concentration was reduced to an endtidal concentration of 0.4 Vol%. With a baby pneumotachograph, minute ventilation, tidal volume, peak inspiratory and expiratory flow and respiratory rate were recorded during quiet breathing. Endtidal pCO2 was measured. Ventilation was then stimulated with 0.2 and 0.41/min CO2 and the same parameters were recorded. Regression analysis was performed for minute ventilation and endtidal pCO2 to obtain the slope which is a parameter for the sensitivity of the chemoreceptor mediated control of ventilation. RESULTS: The tidal volume and peak inspiratory flow were significantly reduced for a dose of 0.6 mg/kg compared to the control group. No statistical difference could be found for any other parameter between the control and study groups. CONCLUSION: We conclude that nasally administered midazolam reduces tidal volume and inspiratory peak flow in spontaneously breathing children at a dose of 0.6 mg/kg b.w. compared to control during halothane--nitrous oxide--oxygen anaesthesia. The CO2 mediated control of respiration under this condition is preserved.

Administration, Intranasal↗
PubMed1996

Comparison of two solutions with different glucose concentrations for infusion therapy during laparotomies in infants.

OBJECTIVE: Comparison of two commercially available solutions for intraoperative infusion therapy during laparotomies in infants using a standardized anesthetic technique (combination of general anesthesia with a caudal block). DESIGN: Prospective, randomized. SETTING: Infusion therapy during laparotomies in infants. PATIENTS AND METHODS: 12 infants aged 1-12 weeks (group I) and 12 infants aged 5-14 months (group II) received at random either solution A with 2.5% glucose and 70 mmol Na+ or solution B with 5.5% glucose and 100 mmol Na+ at a rate of 8 ml/kg/h. INTERVENTIONS: Central venous blood samples after induction of anesthesia and every 60 min for analysis of blood glucose, electrolyte, and hemoglobin concentrations. End of surgery: urine output during the operation and urine glucose and sodium concentrations. Statistical significance within the group: Friedmann Test, between the groups: U test by Wilcoxon, Mann and Witney. SIGNIFICANCE: p < 0.05. RESULTS (given as median and range): In group I blood glucose concentrations rose significantly during surgery, however, there was no significant difference between group A or B after 1 h. A: 234 mg/dl (156-351) vs B: 239 mg/dl (166-329)) or 2 h: A: 254 mg/dl (166-331) vs B: 272 mg/dl (176-468). In group II blood glucose levels rose significantly during surgery, however, children of group B showed significantly higher blood glucose levels than group A after 1 h [A: 119 mg/dl (114-227), B: 203 mg/dl (162-238)], 2 h [A: 154 mg/ml (106-185), B: 284 mg/dl (243-317)] or 3 h [A: 159 mg/dl (116-218), B: 248 mg/dl (201-363)]. The plasma and urine sodium concentrations did statistically not differ between the two solutions. CONCLUSIONS: Solutions containing 5.5% glucose infused with 8 ml/kg/h caused in both age groups of infants intolerable hyperglycemias. In young infants, also a solution containing 2.5% glucose infused at a rate of 8 ml/kg/h leads to hyperglycemia, while in older children this amount of glucose is tolerated. It is recommended that for abdominal surgery in young infants glucose and fluid substitution is separated, in order to infuse glucose at an even lower rate. Still, blood glucose levels have to be monitored closely.

Abdomen↗
PubMed1995

[Three isoflurane preparations from various manufacturers. A comparison of isoflurane concentrations in fresh gas after vaporization with a Drager vaporizer type 19.3].

OBJECTIVES: The purpose of this study was to check the precision of the Dräger vaporizer model 19.3 when filled with three different preparations of isoflurane. METHODS: Six Dräger vaporizers model 19.3 calibrated with forene were filled with forene (Abbott), isoflurane (Lilly) and isoflurane (Pharmacia); gas output was measured by infrared absorption (Irina, Dräger) at vaporizer settings of 0.2, 0.4, 0.6, 0.8, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0 and 5.0 vol%, starting with a fresh gas flow of 2 1/min followed by 4, 6 and 12 1/min. Thus each of the three isoflurane preparations was checked in six different vaporizers and with four different fresh gas flows. RESULTS: Within the concentration range used in clinical practice there was no significant difference in the delivery of the three isoflurane preparations. Each of the six vaporizers produced a controllable and predictable concentration of the three preparations. CONCLUSION: Vaporizers of Dräger type 19.n calibrated with forene deliver the same predictable concentration of the volatile anaesthetic when filled with isoflurane from Lilly or isoflurane from Pharmacia instead of forene and may be used without impairment in patient safety. In addition, no specific calibration with one of the new isoflurane preparations is required.

Calibration↗
PubMed1994

[Spinal anesthesia in infancy using bupivacaine 0.5%. The effect of an adrenaline addition on duration and hemodynamics].

The duration of spinal anaesthesia in infants is short compared to adult patients. When tetracaine is used, the addition of epinephrine significantly prolongs the duration. For bupivacaine, however, the influence of epinephrine on the duration is not clear. We investigated the effects of epinephrine 1:200,000 added to bupivacaine 0.5% on duration and haemodynamics. PATIENTS AND METHODS. Ten former pre-term infants with postnatal respiratory problems, scheduled for bilateral inguinal hernia repair, were enrolled in the study after informed parental consent had been obtained. The infants were fasted at least 4 h prior to surgery. If they did not receive i.v. infusions before surgery, a bolus of 10 ml/kg Ringer's acetate was injected after inserting the i.v. cannula, followed by a continuous infusion of 8 ml/kg 2/3 N NaCl with 5% dextrose. Spinal anaesthesia was performed in a sitting position with 0.6 ml bupivacaine 0.5%. Five patients received plain bupivacaine (group I) and five bupivacaine with epinephrine 1:200,000 (group II). Heart rate registered by ECG and non-invasive blood pressure were recorded prior to positioning the baby for lumbar puncture and 2, 5, 10, and 20 min after injection of bupivacaine. The duration of spinal anaesthesia was defined as the time from injection to the time when the first movements of the legs were observed after stimulation. For testing statistical differences the U test was used between the groups and the Wilcoxon and Wilcox test within the groups. RESULTS. (expressed as median and range). Additional epinephrine significantly prolonged the duration of spinal anaesthesia (group II: 95 min [60-120] vs group I: 50 min [37-85]). Haemodynamic parameters did not differ at any time between or within the groups. In group I, one infant had high spinal anaesthesia with impaired respiration but without cardiovascular effects; after 10 min of assisted ventilation by mask, sufficient respiration as judged by pulse oximetry and clinical observation had returned. The duration of spinal anaesthesia in this child was 60 min. CONCLUSIONS. Epinephrine 1:200,000 significantly prolongs the duration of spinal anaesthesia in former preterm infants. Haemodynamic parameters in this age group remain unchanged during spinal anaesthesia and are not influenced by the addition of epinephrine.

Anesthesia, Spinal↗
PubMed1994

[Effects of propofol and fentanyl on the baroreceptor reflex in geriatric patients].

OBJECTIVE: Increasing age and anaesthetics diminish the baroreflex response to acute changes in blood pressure. This study was designed to investigate the effects of propofol and the combination of propofol with fentanyl on the baroreflex activity in geriatric patients. METHODS: Baroreflex sensitivity was studied by the method of Smyth et al. in 10 elderly (72 +/- 6 yrs) and in 10 younger (48 +/- 6 yrs) patients. Nitroprusside (depressor test) and phenylephrine (pressor test) were used to induce changes in blood pressure of 20 mmHg each to alter the stimulation of the baroreceptor sites. Anaesthesia was induced with propofol, 2 mg x kg-1 b.w.m, and maintained by a continuous infusion of 12 mg x kg-1 x h-1 for 10 min and thereafter with 6 mg x kg-1 x h-1. Then a bolus of fentanyl, 7 micrograms x kg-1 b.w. was injected. Haemodynamic parameters and baroreflex activity were measured in the awake state, 10 min after induction of anaesthesia and 10 min after the administration of fentanyl. Plasma propofol concentrations were determined by HPLC 10 min after induction of anaesthesia with propofol and 10 min after injection of fentanyl. The slope of the linear regression changes in RR-interval [ms] per changes in systolic pressure [mmHg] was used as an index of the baroreflex sensitivity. RESULTS: In the awake state the depressor slopes were significantly reduced by 60% in the elderly patients when compared to the younger patients. In both groups propofol decreased reflex sensitivity by 38% and 41% respectively; this effect was enhanced by the addition of fentanyl in the younger patients, while there was no further effect in the elderly. The pressor slopes did not change significantly in both groups neither with propofol nor with the combination of fentanyl, but again reflex response was significantly less in the elderly patients. CONCLUSION: Our data demonstrate that in geriatric patients the baroreflex control of heart rate already is attenuated in the awake state. Propofol produces a further reduction in reflex sensitivity to an acute decrease in blood pressure; this effect is more pronounced in elderly patients as compared to younger individuals. Acute changes in posture or circulating blood volume during propofol anaesthesia may result in greater cardiovascular instability in older patients due to the greater impairment of circulatory control mechanisms.

Adult↗
PubMed1993

[The hemodynamic effects of atracurium in geriatric patients during intravenous anesthesia using propofol].

OBJECTIVE: Neuromuscular blocking drugs may produce cardiovascular effects by virtue of drug-induced release of histamine or other vasoactive substances from circulating mast cells, effects at cardiac muscarinic receptors or effects at nicotinic receptors at autonomic ganglia. These haemodynamic reactions may be more pronounced in elderly patients, since cardiovascular compensating mechanisms are attenuated with advancing age. The present study was designed to investigate the cardiovascular effects of atracurium with special regard to the reactions in younger adults and in elderly patients. METHODS: 20 patients, ASA class I-II, who underwent a neurosurgical operation (posterior fossa surgery) were studied. The patients were divided into two groups including patients below (group A) and above (group B) 65 years of age. Anaesthesia was induced with propofol (2.5 mg/kg) and maintained with a Propofol/O2/N2O sequence. Under steady state conditions with propofol every patient received 0.5 mg/kg atracurium besylate. Haemodynamic parameters were recorded and plasma concentrations of epinephrine and norepinephrine were determined before (control) and 2, 5 and 10 minutes after the injection of the neuromuscular blocking agent. All measurements were performed before surgical stimulation in supine position. RESULTS: In the younger adults diastolic blood pressure and systemic vascular resistance decreased significantly 2 minutes after injection of atracurium and reached control level 5 minutes after application of the muscle relaxant. In the elderly patients peripheral vascular resistance decreased significantly after 5 minutes and returned to control 10 minutes after the application of atracurium. In both groups cardiac index, systolic and mean arterial pressure, central venous pressure and the parameters related to the pulmonary circulation were not affected. Plasma concentrations of epinephrine and norepinephrine remained essentially unchanged. Side effects due to a release of histamine such as facial or body blush or bronchial spasms were not noted. CONCLUSION: Since the results of the present study suggest that haemodynamic reactions in younger adults and in the elderly are rare, atracurium can be recommended for neuromuscular blockade in elderly patients under propofol anaesthesia.

Adult↗
PubMed1992

Influence of stepwise uncoupling and temporary anoxia on pancreatic enzyme secretion by isolated rat acini.

For special studies on pancreatic diseases a parameter is needed to record alterations of the cellular energy metabolism. In the in vitro model of isolated pancreatic acini, we investigated whether or not at standardized cholecystokinin stimulation the energy-consuming process of enzyme secretion can be used to monitor changes of the energy-supplying capacity. Rat pancreatic acini were isolated via collagenase digestion and characterized by basal and stimulated release of amylase and trypsin, oxygen uptake under resting and maximally uncoupled conditions and by their ability to accumulate actively rhodamine-6G, as a measure of the mitochondrial membrane potential. The stimulation of enzyme release did not find a measurable reflection in rhodamine-6G accumulation and in the respiratory rat. Stepwise uncoupling of oxidative phosphorylation by 2,4-dinitrophenol (DNP) and temporary anoxia were used to simulate disturbances of the pancreatic energy metabolism in vitro. With increasing DNP concentration the enzyme release was significantly reduced. While after 30 min anoxia the enzyme release still exceeded that of unstimulated control, after 60 min anoxia there was no further response to hormonal stimulation. At standardized stimulation and after suitable calibration the enzyme release by acini may be used to monitor alterations of the pancreatic energy metabolism in vitro.

2,4-Dinitrophenol↗
PubMed1991

Influence of anoxia, reoxygenation, and uncoupling on survival, respiration, and trypsin-inhibiting capacity of isolated pancreatic acinar cells.

In the pathogenesis of acute pancreatitis, the events and mechanisms increasing the digestibility of the pancreatic acinar cells are widely unknown. Therefore, the possible contribution of a disturbed energy supply (provoked by anoxia or partial uncoupling) to the induction of autodigestion was studied in experiments on acinar cells isolated from the pancreas. During incubation viability, respiration under normal and maximally stimulated conditions, and trypsin-inhibiting capacity (TIC) of these cells were determined. With increasing duration of anoxia, the portion of surviving cells was strongly diminished, and the number of cells with blebs and vesicularly transformed endoplasmic reticulum was increased. Although the endogenous respiration was not influenced up to 1.5 h of anoxia, 30 min of anoxia substantially decreased the capacity of oxidative energy production. The survival curves were characterized by a self-accelerating course of cell destruction. The alteration of the cellular energy metabolism found its reflection in the decreased TIC of the cells.

2,4-Dinitrophenol↗
PubMed1989

Effects of trypsin, chymotrypsin, and uncoupling on survival of isolated acinar cells from rat pancreas.

To improve the knowledge of the very complex pathogenesis of acute pancreatitis, separated exocrine pancreatic cells were used as an experimental tool. Intact acinar cells were isolated from rat pancreas and the time course of their damage was studied in the presence of increasing activities of trypsin, chymotrypsin and, after, stepwise uncoupling of oxidative phosphorylation, by 2,4-dinitrophenol (DNP). With an increasing degree of uncoupling the half-life period of cells incubated was remarkably reduced. Extracellular trypsin, present in activities comparable with the endogenous trypsinogen content, was not effective in cell killing. Only when the trypsin activity was drastically enhanced was the rate of cell destruction accelerated. Compared with chymotrypsin, isolated acinar cells revealed some resistance to extracellular trypsin. But when the energy production was altered by partial uncoupling the susceptibility of these cells toward the action of trypsin was increased and their life time was remarkably reduced. The potentiation of the effects of trypsin and uncoupling on cell viability demonstrates the contribution of an intact energy metabolism to the protective potential of acinar cells against further noxae.

2,4-Dinitrophenol↗