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Biomedical subjects

M Tryba

Publications and source records attributed to M Tryba.

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

[Histamine release and cardiovascular reactions to implantation of bone cement during total hip replacement].

Cardiovascular reactions to acrylic bone cement in patients with total hip replacement are a common complication. Hypotension and arrhythmias are the most frequently observed symptoms. Elderly patients with fractures of the femoral neck constitute a special risk group. In some patients these reactions can be fatal. The mechanisms suggested to explain these reactions are embolism of air, polymer or fat, reaction to the heat, and toxic or vasodilating effects of the acrylic monomer. In a pilot study and in a case report a significant rise of the plasma histamine was described following cementation of the femur. We therefore performed an investigation to find whether application of bone cement to the femur caused histamine release in elective hip surgery, and, independently of this, also investigated whether premedication with H1- + H2-antagonists had any effect on the cardiovascular reactions due to bone cement implantation into the femoral shaft in elderly patients with hip fracture. METHODS. Part I. In all, 40 patients, scheduled for elective surgical hip replacement were anesthetized by general or epidural anesthesia. Patients were continuously monitored by ECG. Blood pressure was recorded noninvasively at 2-min intervals during the study. Blood samples for the determination of the plasma histamine were taken immediately before implantation of the bone cement into the femur, and 2, 5, and 10 min after. Part II. A further group of 20 patients aged greater than or equal to 70 years with fractures of the femoral neck and in whom total hip replacement was planned were included in the study. In this group, 10 patients were randomly assigned to receive 4 mg clemastine + 400 mg cimetidine i.v. about 15 min before implantation of the bone cement. All patients were operated on under general anesthesia. ECG was monitored continuously and blood pressure was monitored at 2-min intervals during the study. Changes of the blood pressure and heart rate and therapeutic interventions following the implantation of the bone cement were documented. RESULTS. Part I. In 11 of the 40 patients (27.5%) plasma histamine increased by greater than 0.5 ng/ml (9 patients greater than 1 ng/ml). In comparable groups (patients with a control systolic blood pressure less than or equal to 130 mmHg) the histamine responders showed a significantly greater reduction in systolic blood pressure (-5.7 +/- 14.7 vs -17.7 +/- 8.6 mmHg). Part II. In the control group we observed a significantly greater fall in systolic blood pressure than in premedicated patients (41.5 +/- 25.4 vs 11.0 +/- 13.4 mmHg). In the control group 7 of the 10 patients required therapeutic interventions, while in the premedicated group only one therapeutic intervention was necessary (P less than 0.05). DISCUSSION. We have demonstrated that the implantation of acrylic bone cement into the femur may increase plasma histamine by greater than 1 ng/ml. In elderly patients with preexisting cardiac diseases or/and hypovolemia even moderate histamine release can cause serious, sometimes potentially fatal, cardiovascular complications. In this special risk group with hip fractures we found a significant reduction in the frequency of cardiovascular reactions to bone cement implantation in patients premedicated with H1 + H2 antagonists. Because we also observed significant falls in systolic blood pressure in premedicated patients, we assume that the pathogenesis of cardiovascular reactions to bone cement implantation is multifactorial. It may be that potentially lethal complications only occur if two or more of the predisposing factors (hypovolemia, myocardial insufficiency, arrhythmia, embolism, histamine release) are present simultaneously. Pre- and intraoperative measures therefore have to be instituted to eliminate all possible risk factors.

Aged↗
PubMed1991

[Rational prevention of stress hemorrhage--effectiveness, side effects, costs].

Stress ulcer bleeding occurs in special risk groups. The main cause of this complication is the loss of protective mechanisms of the gastric mucosa. Preventive measures aim to strengthen the protective mechanisms or to lower the aggressive factors, mainly the gastric acid. Meta-analysis demonstrates that drugs that enhance the protective mechanisms are superior to a regimen that only reduces the secretion of gastric acid. The most important side effects of stress ulcer prophylaxis are related to the inhibition of gastric acid, the blockade of the cytochrome P450 system and the blockade of central and cardiac H2 receptors. Handling difficulties most often occur during treatment with antacids. The costs of prophylaxis are lowest for sucralfate. Rational decision analysis shows that pirenzepine given as parenteral medication and sucralfate as enteral medication are the most suitable drugs for stress ulcer prophylaxis.

Anti-Ulcer Agents↗
PubMed1991

Prophylaxis of stress ulcer bleeding. A meta-analysis.

Recent studies have reported upper gastrointestinal tract bleeding in 5-25% of intensive care unit (ICU) patients with severe stress despite the use of antacids and/or H2-antagonists. To evaluate the efficacy of this regimen, a meta-analysis of all prospective studies on the prevention of stress bleeding, available from the international literature, was conducted. Only macroscopically visible bleeds were considered. Because alkalinization of the gastric juice has been incriminated in facilitating gastric and pulmonary colonization, agents with little or no influence on the gastric pH have been increasingly investigated in stress bleeding prophylaxis. The meta-analysis was therefore extended to determine the efficacy of two newer substances, pirenzepine and sucralfate, in preventing macroscopically visible stress bleeding, as well as their influence on pulmonary infections and mortality. Antacids and H2-antagonists proved to be significantly superior to untreated controls, with the tendency in favor of antacids administered in short intervals as compared to H2-antagonists. Pirenzepine and sucralfate were significantly superior to H2-antagonists, and sucralfate was as effective as an adequate antacid regimen. Patient groups treated with antacids or H2-antagonists showed a significantly higher risk for the development of nosocomial pneumonia. The most significant differences was found in long-term ventilated patients compared with patients treated with sucralfate. In the same patient group, antacids and H2-antagonists also showed a significantly higher mortality rate than sucralfate.

Critical Care↗
PubMed1990

Stress bleeding prophylaxis with sucralfate. Pathophysiologic basis and clinical use.

The development of acute stress bleeding in intensive-care patients occurs on a multifactorial basis. The basic mechanism lies in the imbalance between aggressive and protective factors. Most intensive care patients show a reduced acid secretion, a reduction of the gastric mucosal blood flow, and a decreased mucus and bicarbonate secretion. Sucralfate enhances most of the defensive mechanisms. These actions are the pathophysiologic basis of the efficacy of sucralfate in the prevention of stress bleeding. Because sucralfate has only a minor influence on the gastric pH and at the same time has proven bactericidal effects, gastric and gut bacterial overgrowth is significantly reduced. These effects explain the observed differences in mortality between sucralfate and alkalinizing drugs like antacids or H2-antagonists. The indications and limits of sucralfate in stress bleeding prophylaxis are pointed out.

Clinical Trials as Topic↗
PubMed1989

Side effects of stress bleeding prophylaxis.

Conventional stress bleeding prophylaxis with antacids or histamine (H2)-antagonists, as well as the newer mucosa-protective drugs pirenzepine and sucralfate, are satisfying most of the clinicians with regard to efficacy of stress bleeding prevention. Therefore, potential side effects are attaining crucial importance with regard to the drugs to be used. Pharmacologic blockade of cardiac H2-receptors increases the risk of bradycardia and negative inotropic effects as well as coronary vasoconstriction at least in the presence of elevated plasma histamine levels. Intracardiac injection of pirenzepine can lead to temporary tachycardia. Elderly patients have been shown to be at an increased risk of side effects to the central nervous system when treated with H2-antagonists. These drugs can also induce toxic effects in the liver. Cimetidine leads to interactions with a number of drugs used in the intensive care unit. In patients with pre-existing pulmonary diseases, H2-antagonists have been demonstrated to increase pulmonary bronchoconstriction. Alkalinization of the gastric juice is associated with a significant increase in colonization of gram-negative bacteria in the stomach. In intubated patients, aspiration of stomach contents occurs in 30 to 40 percent of the patients. A number of studies have shown a direct correlation between alkalinization of the gastric juice and pulmonary infections. Sucralfate and to a lesser degree pirenzepine can reduce the risk of pulmonary infections. Sucralfate also exerts a bactericidal effect. Recent investigations support the hypothesis that alkalinization of the stomach also increases the risk of systemic infections. This may be the main reason for the observation that at least in ventilated patients sucralfate, unlike H2-antagonists or antacids, leads to a significant reduction of the mortality rate compared with conventional stress bleeding prophylaxis.

Bacteria↗
PubMed1989

[Retard morphine in the long-term therapy of severe tumor pain].

35 patients with severe cancer pain received oral retard morphine. Pain reduction was achieved in each case; duration of effectiveness was between 8 and 12 hours. Mean daily dose was 230 mg morphine, but in individual cases the maximal daily dose had to be over 800 mg. The Karnofsky index of physical capacity was increased in all patients. The main side effect was constipation, which actually increased in the course of treatment. On the other hand, nausea and vomiting decreased after a few weeks. No dependence developed in any of the patients. This form of morphine medication thus was effective over long periods and it has become an important part in the range of strongly effective analgesics.

Adult↗
PubMed1989

Treatment of acute migraine with subcutaneous GR43175 in West Germany.

A subcutaneous preparation of GR43175, a novel antimigraine 5-HT 1-like agonist, was considered to represent a convenient way of administering the drug to patients during an acute migraine attack. In a series of open, uncontrolled dose-ranging studies, 82 patients with migraine were assessed serially for changes in severity of headache and associated symptoms following subcutaneous GR43175 in doses of 1-4 mg. Subcutaneous injection of 3 mg or 4 mg was found to be most effective. Within 60 min, 90% of patients had obtained complete relief of all migraine symptoms. Tolerability was good, 59% of patients reporting no adverse effects. Those reported mainly comprised transient local irritation to the injection. There were no changes attributable to GR43175 in heart rate, blood pressure, ECG readings or laboratory parameters.

Adult↗
PubMed1989

[A new procedure for decreasing transfusion risk in administration of fresh frozen plasma].

About 2% of patients in central Europe who receive transfusions of whole blood or blood components still develop typical transfusion-induced infections, most often non-A-non-B hepatitis. The risk of infection increases in direct correlation to the number of transfused units, which mainly means the number of different donors. We have developed a new and simple method that leads to a significant reduction of infection risk in patients who receive multiple units of fresh frozen plasma. Plasma from individual donors is gathered over a period of about 9 months, after which 5000-6000 ml is stored separately for each donor. The plasma of each donor is numbered, e.g. 1/87, 2/87, 3/87 ... 1/88. This procedure allows an immediate overview of which are the oldest units. If a patient needs multiple units of fresh frozen plasma, he receives only plasma from a single donor. The donors are under strict control; the plasma must be stored for at least 3 months. Only if the donors are free of any signs of infections such as hepatitis or HIV during that period is the plasma allowed to be transfused. If only a few units will be transfused the plasma store can be refilled within 2-4 weeks. This regimen reduces the risk of transfusion-induced infections in patients who receive 10 double units of fresh frozen plasma by at least 90%. Apart from the additional logistic costs, only a refrigerator with the capacity to store a large number of plasma units is needed.

Blood Donors↗
PubMed1989

[Interactions of H2 antagonists and non-depolarizing muscle relaxants].

Many drugs potentiate the action of non depolarizing relaxants. These interactions are of clinical importance if such drugs are administered during the perioperative period. H2 Antagonists are increasingly often used for premedication. Cimetidine inhibits the elimination of a number of drugs used in the perioperative period. We therefore investigated whether H2 antagonists enhanced neuromuscular blockade by vecuronium, a medium short acting non depolarizing muscle relaxant. METHODS. The study was carried out in 24 female patients (ASA class I or II) scheduled for microsurgical procedures. Neuromuscular transmission was recorded electromyographically using four stimulations every 20 s to the ulnar nerve. After induction with thiopentone, anesthesia was maintained with fixed concentrations of volatile anesthetics. Fentanyl was administered for additional analgesia. Vecuronium was used as the sole muscle relaxant. Fixed repetitive doses of vecuronium (0.8-1.2 mg) were injected whenever the T1 returned to 25%. This time interval was defined as the T1-25 period. The study proper started when the T1-25 period had stabilized. After two control periods, six patients in each group received either 200 or 400 mg cimetidine or 100 mg ranitidine. The fourth group was the control group. The T1-25 periods and the maximal EMG depression were recorded automatically for at least two further periods. The first measured period was recorded as 100% and the length of each other periods was calculated as a percentage of the control period. This method enables an intraindividual comparison of the length of the T1-25 period and the maximal EMG depression before and after administration of the H2 antagonists. A two-tailed Student's t-test was used to test statistical significance, P less than 0.05 being accepted as significant. RESULTS. In the control group and in the group with 200 mg cimetidine or 100 mg ranitidine no statistical significant prolongation of the T1-25 period or of the maximal EMG depression could be observed, while after 400 mg cimetidine there was significant prolongation (mean 161 +/- 14.8%) of the T1-25 period and significantly greater EMG depression compared with the pre-cimetidine values. In the groups with 200 mg cimetidine or 100 mg ranitidine few patients showed prolongation of the T1-25 period up to 130%. DISCUSSION. Our results confirm experimental studies that have shown cimetidine to enhance aminoglycoside--relaxant interactions. Because we found an immediate response to the administration of the H2 antagonists, the interaction cannot be on the elimination side; it must be at the neuromuscular junction. Experimental investigation has shown that calcium reverses the cimetidine effects. It is therefore probable that the cimetidine--relaxant interaction occurs at the presynaptic level. Careful observation seems to be necessary if H2 antagonists, especially cimetidine, are administered intraoperatively at the same time as drugs that also enhance

Adult↗
PubMed1989

[Vecuronium in dystrophia myotonica (Curschmann-Steinert)].

An emergency laparotomy was performed in a 31-year-old female (body wt 48 kg) with known myotonic dystrophy. Premedication with dantrolene (1 mg/kg i.v.) was used to prevent a myotonic response. Muscle relaxation was monitored electromyographically. Following induction with fentanyl (0.3 mg) and thiopental (200 mg), muscle relaxation was achieved with 2 mg vecuronium titrated for about 3 min until the T1-response was reduced to 10%. The recovery time was normal. A repetitive dose of 0.5 mg vecuronium was necessary after 20 min, when the T1 reached 60%. Extubation and the early postoperative period were uneventful. Because of the unknown predisposition of our patient for the development of malignant hyperthermia, anesthesia was performed with trigger-free anesthetics.

Adult↗