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Biomedical subjects

A Lienhart

Publications and source records attributed to A Lienhart.

At least 19 recordsLinked to original sources
PubMed1992

Tumor necrosis factor-alpha in liver transplantation and resection. No evidence for a key role in ischemia-reperfusion injury.

Experimental studies have shown that liver ischemia-reperfusion induces Kupffer cell activation and tumor necrosis factor-alpha (TNF alpha) release. The aim of this work was to determine whether severe hepatic ischemia and subsequent reperfusion triggers TNF alpha release in man. Serum TNF alpha was measured before and 3, 10, 30, 60, 120 min after revascularization and postoperatively at day 1 and 2 in 11 patients with orthotopic liver transplantation (group 1) and 4 patients with liver resection with vascular occlusion (group 2). In group 1, TNF alpha levels decreased during the first few minutes of reperfusion, then increased slightly to peak at 120 min (40 +/- 13 pg/ml). Primary non-function occurred in 1 patient in whom low peroperative levels of TNF alpha levels were measured. In group 2, no significant changes in TNF alpha levels were observed. These data, in a small number of patients: (a) show that hepatic ischemia-reperfusion does not result in major TNF alpha production; (b) do not support a primary pathogenic role for TNF alpha in damage after ischemia-reperfusion in humans.

Humans↗
PubMed1992

[Effect of hygrophobic filter or heated humidifier on peroperative hypothermia].

A study was carried out to find out whether the use of a hygrophobic filter (Pall, Ultipor) or of a heated humidifier (Dräger, Aquapor) during surgery had any effect on a patient's intraoperative core temperature and thermal balance. Seventy-five ASA I or II patients scheduled for gynaecological surgery were randomly assigned to three groups: group A (n = 25), where no warming device was used; and two groups (n = 25 for each) where inhaled gases were humidified and heated with either a hygrophobic filter set up between the endotracheal tube and the Y-piece (group B) or a heated humidifier set to 100% saturation at a temperature of 41.5 degrees C (group C). The patients were all anaesthetised with the same technique (thiopentone 5 mg.kg-1, dextromoramide 0.03 mg.kg-1 and 0.1 mg.kg-1 of either pancuronium or vecuronium, followed by enflurane with nitrous oxide in oxygen); the perfused fluids were not heated. Room, tympanic, rectal, oesophageal and four skin (thorax, arm, leg, thigh) temperatures were measured with calibrated Exacon thermistances, on arrival in the operating theatre, during induction, every ten minutes for two hours, and then every twenty minutes for two hours more. Ramanathan's and Burton's formulae were used to calculate mean skin temperature and heat loss respectively. In the recovery room, patients were warmed up with an electric blanket. Shivering was ranked from "0" to "+ +". There were no differences between groups as far as age, drug doses, perfusion volumes and room temperature were concerned.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, Inhalation↗
PubMed1992

[Analgesic effect of ibuprofen in pain after episiotomy].

The relief of post-episiotomy pain was investigated in three groups of women, ranked ASA 1 or 2, using either a single dose of 400 mg of ibuprofen (n = 31), or 1 g of paracetamol (n = 28) or placebo (n = 31). Pain intensity was assessed with a visual analogic scale, a verbal scale and pain relief scores after half an hour, 1, 2, 3, 4, 5 and 6 h. The day after treatment, patients rated the quality of pain relief, and were asked whether they wished to take again the same drug for the same type of pain. In the placebo and paracetamol groups, respectively 22 and 16 patients asked for usual treatment before the sixth hour, whereas only 5 did so in the ibuprofen group (p less than 0.001). Ibuprofen was more effective after one hour than either of the other two drugs, whatever the scale or parameter used. In the ibuprofen group, the lower pain score was observed at the third hour. At six hours, the pain score did not differ from that three hours earlier. On the day after treatment, 22 patients from the ibuprofen group considered pain relief to have been good or excellent, versus 8 and 5 in the paracetamol and placebo groups respectively (p less than 0.001). Similarly, 24 patients from the ibuprofen group would accept the same drug again for the same type of pain, as opposed to 8 and 5 from the paracetamol and placebo groups respectively (p less than 0.01). The only side-effect reported was abdominal pain in one patient (placebo group).(ABSTRACT TRUNCATED AT 250 WORDS)

Acetaminophen↗
PubMed1992

[Monochromatic infrared halogenated gas analyzer and handling errors].

Monochromatic infrared gas spectrometers cannot identify volatile agents. Such an analyser (Capnomac, Datex) was tested while performing two errors: a) erroneous selection of the agent on the analyser, the vaporizer being filled with the correct agent; b) total or partial filling of the vaporizer (Vapor 19, Dräger) with an incorrect agent, the analyser being set for the agent the vaporizer was specified for. Three agents were studied, halothane (H), enflurane (E) and isoflurane (I). Each experiment was made in triplicate, the vaporizer being dried out between each. In case of erroneous selection on the analyser, differences between E and I were very small. When H was erroneously selected, the concentration displayed was six times higher, and when E or I was selected instead of H, the concentration displayed was six times lower than expected. In the 3.3-3.5 m band, H transmittance was six times higher than those of E and I. The agent selection control changes the gain so as to correct for the selected agent (gain for H: 12.0, E: 2.24, I: 1.89). In case of erroneous filling of the vaporizer, the concentration displayed was always different from that expected. When E or I was delivered with an H vaporizer, the analyser being set on H, the concentration displayed was 3 to 9 times higher than the concentration that had been set. On the other hand, when H was delivered with an E or I vaporizer, the analyser being set to E or I, the concentration displayed was 4 to 8 times lower.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, Inhalation↗
PubMed1992

[Desflurane (I 653) and sevoflurane: halogenated anesthetics of the future?].

Sevoflurane is an halogenated methyl isopropyl ether. It is potent, non explosive and non flammable. It reacts with soda lime to form traces of a related ether which has not been shown to have any toxic effect on animals chronically exposed to it in a closed system. Induction of anaesthesia with sevoflurane is rapid and smooth, as predicted by a blood/gas partition coefficient of about 0.6 and an acceptable odour which allows the use of concentrations of up to 10%. Its MAC has been reported to vary between 1.7 and 2.3 vol %. Sevoflurane causes dose-dependent cardiovascular and respiratory depression. Its effect on the cerebral circulation is similar to that of isoflurane. The extent of biotransformation is similar to that of enflurane, but its low solubility and rapid elimination confine this to the period of inhalation. No toxic effects on the kidneys, liver and haematopoietic system have been found. Desflurane is a fluorinated methyl ether, structurally very similar to isoflurane. It is non flammable and non explosive at clinical concentrations. It is more stable in the presence of soda lime than any of the volatile anaesthetic agents available. This agent must be delivered with a thermostated vaporizer within a closed circle system, as its boiling point is 23.5 degrees C. Desflurane is less potent than isoflurane. Its MAC has been estimated to be about 7.2 vol % in man. Desflurane did not lead to any liver, lung or kidney injury in laboratory rats, even during hypoxia and enzyme induction. Desflurane undergoes little biotransformation, although the presence of volatile metabolites or covalent tissue-bound products cannot be excluded.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, Inhalation↗
PubMed1992

[Physical modeling of inhalation anesthesia].

A new physical model simulating the pharmacokinetics of volatile anaesthetics is presented. It consists in a ventilator connected to a water manometer. Gas is removed from the gaseous part of this manometer with a constant rate pump. This gas flow is directed thereafter into three capacitances with valves and pumps: one capacitance only contains air, representing the lungs, and the other two olive oil, representing the visceral and muscle compartments. Halothane, enflurane and isoflurane (1 vol%) were administered to this model with different values of cardiac output and alveolar ventilation. There was good concordance between the values of FA/FI that were measured in this model and those calculated by computer simulation. No correction factor was required. Such a physical model may therefore be used to test new techniques of administration of volatile agents.

Anesthesia, Inhalation↗
PubMed1992

[Effects of nifedipine premedication on peroperative hypothermia].

The intraoperative time-course of core temperature in patients premedicated with nifedipine (n = 30) was compared to that of control patients (n = 30). Distal oesophageal temperature (TCORE) was recorded every five minutes during total hip replacement in 60 adults ranked ASA 1 to 2. Patients in the control group were only premedicated with 100 mg of oral hydroxyzine. The treatment group consisted of 30 patients taking nifedipine for blood pressure control or coronary insufficiency. They were given 10 mg sublingual nifedipine as well as the hydroxyzine premedication. Anaesthesia was induced with thiopentone, fentanyl and vecuronium, and maintained with nitrous oxide in oxygen and halothane in a semi-closed circuit. The slopes of the time-course for TCORE were established for each patient, using two linear regressions, between 0 and 0.5 h and from 1 to 2 h. The two groups did not differ in age, weight, ambient temperature, blood pressure, heart rate, and volume of unwarmed blood transfused. TCORE differed significantly from the 25th minute on until the end of the study period. Contrary to all expectation the TCORE at 2 h was higher in the nifedipine group (34.85 +/- 0.09 degrees C) than in the control group (34.01 +/- 0.14 degrees C, p < 0.001). TCORE decreased more rapidly in the control group during the first study interval (0 to 0.5 h), -1.50 +/- 0.60 degrees C.h-1 vs -2.34 +/- 1.02 degrees C.h-1 (p < 0.001). The second slopes did not differ particularly (-0.96 +/- 1.32 degrees C.h-1 vs -0.90 +/- 0.42 degrees C.h-1 respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1992

[Postoperative shivering: analysis of main associated factors].

This study was carried out in 75 female patients, ranked ASA 1 or 2, during recovery from balanced general anaesthesia. It aimed to find out the main determinants of postoperative shivering and its thermal effects. Skin and oesophageal temperature were recorded every ten minutes. Mean skin and body temperatures, and the intraoperative energy balance were calculated. There was no additional source of heating. Shivering was ranked from 0 to 2. Statistical analysis showed that the starting mean core and body temperatures were the only factors correlated with shivering and its intensity, whereas mean skin temperatures, age and opioid doses were not. Between 33.5 and 36.5 degrees C, there was a linear relationship between the oesophageal temperature at the end of anaesthesia and the incidence of shivering. A decrease of 1 degrees C in core temperature increased the probability of shivering by 33%. At 35.4 degrees C, 50% of patients shivered. There was a homogenous group of patients whose oesophageal temperature at the end of anaesthesia was between 35 and 36 degrees C. In this group, there was no significant difference between starting skin temperatures, whether the patient shivered or not. However, the core temperature of those within that group that did shiver returned to normal levels more quickly than in those that did not shiver. These data underlined the essential role played by core temperature at the end of anaesthesia in postoperative shivering and its intensity, as well as the heat producing value of shivering. It would therefore seem logical to prevent postoperative shivering by avoiding intraoperative hypothermia.

Adult↗
PubMed1992

Oxygen uptake during recovery following naloxone. Relationship with intraoperative heat loss.

The increased metabolic and respiratory demand during naloxone recovery from opioid-based anesthesia could be related to the return of thermoregulation in hypothermic patients and thus be avoided by preventing intraoperative hypothermia. In this study, we measured O2 uptake (VO2) during naloxone-induced recovery in two groups of patients to determine the effect of intraoperative heat loss on postoperative VO2 changes. In seven patients, intraoperative hypothermia was prevented (normothermic group), whereas hypothermia was allowed to develop in seven other patients (hypothermic group). Core and skin temperatures were measured throughout the study to calculate changes in body heat content. Before naloxone antagonism of fentanyl-supplemented anesthesia, core temperature (mean +/- SEM) was 36.8 +/- 0.1 degrees C in the normothermic group and 34.2 +/- 0.2 degrees C in the hypothermic group (P less than 0.001). After titrated administration of naloxone during recovery, VO2 and minute ventilation (VE) increased in the hypothermic group, by 114 +/- 37% and 97 +/- 52% respectively (P less than 0.05), with a three-fold increase in four patients. In the normothermic group, VO2 increased significantly less (25 +/- 5%), without any significant change in VE. The change in VO2 and VE was significantly greater in patients who were hypothermic. VO2 was integrated throughout the recovery period to calculate recovery energy expenditure. Recovery energy expenditure and intraoperative heat loss were highly correlated (r = 0.88; P less than 0.01). This study demonstrates that the metabolic and respiratory stresses associated with naloxone-induced recovery from opioid-based anesthesia depend on the intraoperative heat loss and can therefore be reduced by preventing intraoperative hypothermia.

Anesthesia Recovery Period↗
PubMed1991

Droperidol prevents serotonin-induced bronchospasm in the guinea pig.

The effects of droperidol on bronchoconstriction induced by serotonin (5-HT) were studied in mechanically ventilated, paralyzed guinea pigs that had been anesthetized with pentobarbital. Droperidol did not modify the resting bronchial tone but prevented the bronchoconstrictor effects of 5-HT in a dose-related manner. Pretreatment with propranolol, hexamethonium, or prazosin did not alter the protective effects of droperidol on 5-HT-induced bronchoconstriction. The bronchoconstrictor responses to histamine or acetylcholine were not affected by droperidol. These results suggest that the protective effects of droperidol on 5-HT-induced bronchoconstriction are mediated through 5-HT receptor blockade on bronchial smooth muscle.

Acetylcholine↗
PubMed1990

Clinical reliability of measured and calculated oxygen parameters in surgical patients: influence of hyperventilation.

The acid-base and oxygen status were assessed in patients undergoing abdominal surgery. We determined the measured and calculated parameters described by Siggaard-Andersen in arterial and mixed venous blood before, during and after a controlled hyperventilation. In these dynamic conditions, the mixed venous calculated p50 showed the most interesting variations. Derived values in arterial blood were unreliable since: 1) fitting to hyperbolic tangent function is not possible when SaO2 greater than 0.98; 2) in these patients, the arterio-venous difference in CtO2 is different from 2.3 mmol/L. The acute changes in calculated p50 are in agreement with the effect of hyperventilation on oxygen status.

Abdomen↗
PubMed1989

[Anesthesia in myotonia].

Myotonia is defined as a persistent contraction of skeletal muscles after their stimulation. This contracture is not prevented or relieved by regional anaesthesia or muscle relaxants. The sensitivity to non-depolarizing muscle relaxants is usually normal. Suxamethonium, neostigmine, hypothermia, a rise in kalaemia should be avoided. There have been case reports of malignant hyperthermia in patients with myotonia congenita. Dystrophia myotonica is the second most frequent of the inherited muscle diseases, after Duchenne's dystrophy. The severity of the disease is due more to the muscular atrophy and the multiple organ involvement than to the abnormal contraction. Atrioventricular heart block and dysrhythmias are more common than heart failure. Prolonged apnoea and pneumonia are the main risks of anaesthesia. In severe cases, exists a restrictive respiratory insufficiency which is preceded by a fall in the maximum expiratory pressure. Dysphagias and inefficient coughing may occur early. An increased susceptibility to hypnotic drugs and opiates is a common feature. Spontaneous sleep apnoeas should be sought before anaesthesia, especially by using pulse oximetry. The anaesthetic implications are reemphasized.

Anesthesia↗
PubMed1989

[A mistake in the filling of a vaporizer detected by an infrared analyser of halogenated anesthetic agents].

An anaesthetic pitfall related to an incorrectly filled vaporizer, without harmful effects on the patient, is reported. A halothane specific vaporizer has been accidentally partially filled with enflurane. The incident was suspected when the Datex Normac infrared analyser, calibrated for halothane, displayed an inspired concentration of 0.83% v/v, whereas the Dräger Vapor 19 vaporizer dial was set to deliver 0.4% v/v with a fresh gas flow of 2.7 l.min-1 to a circle system. The analyser uses infrared gas spectrometry, in the 3.3 to 3.5 microns band which contains the absorption peaks of halothane, enflurane, isoflurane and methoxyflurane. The four agents have different transmittances, with halothane the greatest. The agent selection control changes the gain to correct for the selected agent. The measurements are only accurate when only one agent is present at a time. In the reported case, the displayed concentration was very high because the high gain of halothane (12.0) was applied to enflurane (enflurane gain: 2.24). An in vitro experiment measuring the values of different enflurane/halothane mixtures, carried out with the involved vaporizer, showed that it contained, at the time of the incident, a mixture of 20% enflurane and 80% halothane. It may therefore be possible to detect a vaporizer filling error when the values "measured" by the analyser are not in concordance with those set on the vaporizer. Filling an enflurane vaporizer with halothane is more dangerous, as it results in a high halothane output with a Normac "enflurane" inspired concentration remaining very low. The indexed pin safety system remains the best means of avoiding wrong vaporizer filling.

Anesthesia, General↗
PubMed1989

Vascular occlusions for liver resections. Operative management and tolerance to hepatic ischemia: 142 cases.

The intra- and early postoperative courses of 142 consecutive patients who underwent liver resections using vascular occlusions to reduce bleeding were reviewed. In 127 patients, the remnant liver parenchyma was normal, and 15 patients had liver cirrhosis. Eighty-five patients underwent major liver resections: right, extended right, or left lobectomies. Portal triad clamping (PTC) was used alone in 107 cases. Complete hepatic vascular exclusion (HVE) combining PTC and occlusion of the inferior vena cava below and above the liver was used for 35 major liver resections. These 35 patients had large or posterior liver tumors, and HVE was used to reduce the risks of massive bleeding or air embolism caused by an accidental tear of the vena cava or a hepatic vein. Duration of normothermic liver ischemia was 32.3 +/- 1.2 minutes (mean +/- SEM) and ranged from 8 to 90 minutes. Amount of blood transfusion was 5.5 +/- 0.5 (mean +/- SEM) units of packed red blood cells. There were eight operative deaths (5.6%). Overall, postoperative complications occurred in 46 patients (32%). The patients who experienced complications after surgery had received more blood transfusion than those with an uneventful postoperative course (p less than 0.001). The length of postoperative hospital stay was also correlated with the amount of blood transfused during surgery (p less than 0.001). On the other hand, there was no correlation between the durations of liver ischemia of up to 90 minutes and the lengths of postoperative hospital stay. The longest periods of ischemia were not associated with increased rates of postoperative complications, liver failures, or deaths. There was no difference in mortality or morbidity after major liver resections performed with the use of HVE as compared with major liver resections carried out with PTC alone, although the lesions were larger in the former group. It is concluded that the main priority during liver resections is to reduce operative bleeding. Vascular occlusions aim at achieving this goal and can be extended safely for up to 60 minutes.

Aged↗