Search PubMed⌕ Search

Biomedical subjects

T Prien

Publications and source records attributed to T Prien.

At least 19 recordsLinked to original sources
PubMed2001

Minimal flow sevoflurane and isoflurane anaesthesia and impact on renal function.

BACKGROUND AND AIM: Compound A generation and accumulation in sevoflurane anaesthesia is dependent on fresh gas flow. We investigated the extent of generation of compound A. METHODS: After Institutional Review Board approval and informed consent, patients with normal renal function were randomized to receive either sevoflurane (n = 33) or isoflurane (n = 43) minimal flow anaesthesia (0.5 L min-1) for at least 2 h under standardized conditions. Compound A concentrations were quantified and blood and urine samples were taken to assess renal involvement. Both groups were comparable. RESULTS: No significant differences concerning blood chemistry and urine measurements were found. The maximum mean compound A concentration was observed 90 min after flow reduction being 40 +/- 9 p.p.m. at a corresponding mean sevoflurane concentration of 2.1 +/- 0.5 vol%. Mean inspiratory compound A exposure was 102 +/- 33 p.p.m h-1. CONCLUSION: Compound A concentrations using 0.5 L min-1 fresh gas flow and a heated absorber were higher than previously published values using an inflow of 1 L min-1. Compound A exposure was similar to other clinical studies which did not show changes in renal and hepatic function.

Adult↗
PubMed2000

[Indications for central versus peripheral regional anesthesia].

Serious neurological complications caused by spinal hematoma or abscess following central neuraxial block have been reported more often during the last years. In contrast, severe complications are extremely rare associated with peripheral nerve blocks. Concerned about the safety of spinal and epidural anesthesia, we encourage the use of peripheral regional techniques for procedures on the lower extremity and especially for postoperative regional analgesia. Motor block due to lumbar epidural anaesthesia using high concentrations of local anesthetic makes spinal hematoma or abscess difficult to recognize. Therefore, low concentrations of local anesthetic should be used for postoperative epidural analgesia. Any increase in motor block following neuraxial blockade should raise the suspicion of a spinal compression (e.g. hematoma or abscess). Other symptoms are back pain, radicular pain or paresthesia and incontinence. Disastrous neurological injuries can only be prevented by immediate diagnosis (MR, CT or myelography) and therapy (surgical decompression).

Anesthesia, Conduction↗
PubMed2000

Intra-articular clonidine analgesia after knee arthroscopy.

Recently, it was suggested that peripherally-mediated analgesia can be accomplished by the intra-articular delivery of the mu-opioid morphine or of the a2-agonist clonidine. This clinical study assesses the potential peripheral analgesic effect of the combination of morphine and clonidine after intra-articular administration. Sixty patients (American Society of Anesthesiologists status I or II) undergoing arthroscopic repair of the knee during general anaesthesia were randomized to receive after operation, in a double-blind manner, either 1 mg morphine intra-articularly (group 1); 150 microg clonidine intra-articularly (group 2); or 1 mg morphine + 150 microg clonidine intra-articularly (group 3); or normal saline intra-articularly (group 4) in a volume of 30 mL, respectively. Visual analogue pain scores (VAS), duration of analgesia as defined by first demand for supplemental analgesics, subsequent 24 h consumption of postoperative supplementary analgesics, and patient satisfaction were evaluated. Co-administration of morphine + clonidine (group 3) resulted in a significant VAS reduction at 2 h after injection compared with the other groups. There was a tendency towards a lower need for supplementary rescue analgesia and towards a more prolonged analgesia in group 3 (211 min +/- 224 min SD) compared with group 1 (173 min +/- 197 min SD) and group 4 (91 min +/- 21 min SD). More patients were very satisfied with the postoperative analgesic regimen receiving the combination of morphine and clonidine (group 3) at 24 h postoperatively. Thus we conclude, that the peripheral co-delivery of an opioid and an a2-agonist will result in improved postoperative pain relief, when compared with each single agent given alone.

Adrenergic alpha-Agonists↗
PubMed1999

[Concept for continuing medical education of the European Union of Medical Specialists--EUMS].

In Europe, emerging national structures of continuing medical education (CME) have to be connected in an umbrella structure of national authorities featuring the international exchange of accreditation and credits. In this umbrella structure, following topics need to be addressed: harmonization of the system of accreditation of providers of formally planned CME, the formulation of basic requirements for providers of formally planned CME, the system of quality assessment of the provided CME, and the system of awarding of CME credits to individual specialists.

Education, Medical↗
PubMed1998

Arterio-venous carboxyhemoglobin difference suggests carbon monoxide production by human lungs.

Carbon monoxide is hypothesized to be produced by the enzyme heme oxygenase predominantly in liver and spleen, bound to hemoglobin, and excreted by the lungs. Thus, venous carboxyhemoglobin is expected to be higher or equal to arterial carboxyhemoglobin. Unspecific inflammatory stimuli have been shown to induce heme oxygenase in lung tissue possibly leading to pulmonary carbon monoxide production. Arterial and central venous carboxyhemoglobin levels were measured in critically ill patients on the third day of ICU stay (n = 59) as well as in otherwise healthy humans prior to orthopedic surgery (n = 29). Arterial and central venous carboxyhemoglobin were higher in ICU patients than in healthy humans, respectively. In both groups, arterial carboxyhemoglobin was significantly higher than central venous carboxyhemoglobin. The arteriovenous carboxyhemoglobin differences were similar in both groups. The data suggest (a) increased CO-generation in critical illness and (b) pulmonary CO-production in healthy and critically ill humans.

Arteries↗
PubMed1998

[Is there a means for cost reduction in intensive care fluid therapy without a loss of quality?].

Cost reduction in fluid therapy may be possible without a loss in quality of medical therapy if the following principles are adhered to. 1: Compare the prices of different manufacturers. 2: The greater the product unit, the cheaper the milliliter. Adherence to this principle is limited by hygienic and logistic considerations. 3: 0.9% NaCl-solution is cheaper than Ringer's lactate-solution. Lactated Ringer's solution should be used, only, if there are contraindications against the higher solute concentrations and tonicity of 0.9% NaCl. 4: Crystalloids are cheaper than colloids. When choosing between these two options intravasal duration of action and specific adverse events must be considered. 5: Cost reduction by differential indication of artificial colloids. Comparing prices, one must consider risk of anaphylactoid/anaphylactic reactions, duration of action, limitation of dosage and possible hemostasis disorders. 6: Restrictive use of albumin. Albumin is the most expensive colloid. There are no reasons for routine use.

Chemistry, Pharmaceutical↗
PubMed1998

Comparison of the haemodynamic effects of nitric oxide synthase inhibition and nitric oxide scavenging in endotoxaemic sheep.

OBJECTIVE: The present study compared the effects of nitric oxide (NO) synthase inhibition and NO scavenging with haemoglobin in endotoxaemic sheep. DESIGN: 12 sheep were instrumented for chronic study. Six sheep received LG-nitro-arginine-methylester (L-NAME, 2.5 mg/kg bolus followed by a continuous infusion of 0.5 mg/kg per h), the other 6 sheep received pyridoxalated haemoglobin polyoxyethylene conjugate (PHP, 100 mg/kg bolus followed by a continuous infusion of 20 mg/kg per h). MEASUREMENTS AND RESULTS: Haemodynamic and oxygenation parameters were measured in healthy sheep, after infusion of Salmonella typhosa endotoxin (10 ng/kg per min) for 24 h and after infusion of L-NAME or PHP. The infusion of endotoxin resulted in a hypotensive, hyperdynamic circulation. Infusion of L-NAME increased mean arterial pressure (MAP) from 76.1 +/- 4.2 mmHg to normal values of 95.8 +/- 5.7 mmHg (p < 0.05). PHP increased MAP from 73.0 +/- 3.0 to 88.6 +/- 4.7 mmHg (p < 0.05). This increase in MAP was associated in the L-NAME group with a more prominent drop in cardiac index (from 10.2 +/- 0.4 to 7.0 +/- 0.51.min-1.m-2; p < 0.05) than in the PHP group (from 10.7 +/- 0.2 to 9.3 +/- 0.61.min-1.m-2). During the first 90 min of infusion, cardiac index remained lower in the L-NAME group than in the PHP group. The increase in pulmonary vascular resistance was also higher in the L-NAME group. CONCLUSION: These results suggest, that at the doses used in the experiment, NO scavenging with PHP has smaller effects on cardiac index and pulmonary vascular resistance than NO synthase inhibition with L-NAME. Therefore, the concept of NO scavenging in hyperdynamic sepsis should be further evaluated.

Animals↗
PubMed1997

Haemodynamic effects of dopexamine and nitric oxide synthase inhibition in healthy and endotoxaemic sheep.

Chronically instrumented awake healthy sheep (n = 6) received the synthetic catecholamine, dopexamine, during or without a background infusion of the nitric oxide synthase inhibitor. L-nitro-arginine-methylester (L-NAME). Three days later, hypotensive-hyperdynamic circulation was induced and maintained by continuous infusion of Salmonella typhosa endotoxin (10 ng/kg per min). After 24 h of continuous endotoxin infusion, the dopexamine L-NAME protocol was repeated. In healthy and endotoxaemic animals with and without nitric oxide synthase inhibition dopexamine caused the same haemodynamic changes: heart rate and cardiac output increased, mean arterial pressure and systemic vascular resistance decreased. L-NAME infusion induced normalisation of the hypotonic-hyperdynamic circulation in endotoxaemic animals. Dopexamine reduced some adverse effects of L-NAME treatment, like increased pulmonary vascular resistance and decreased oxygen delivery. In conclusion the haemodynamic effects of dopexamine are independent of the amount of nitric oxide production. Dopexamine may attenuate some of the adverse effects of nitric oxide synthase inhibition.

Adrenergic beta-Agonists↗
PubMed1997

Secretion of brain natriuretic peptide in patients with aneurysmal subarachnoid haemorrhage.

BACKGROUND: Subarachnoid haemorrhage is commonly associated with natriuresis and hyponatraemia. One possible explanation for these features is a defect in the central regulation of renal sodium reabsorption with increased secretion of a natriuretic factor. We investigated whether excess sodium secretion in patients with subarachnoid haemorrhage is related to increased secretion of natriuretic peptides or to the presence of digoxin-like immunoreactive substances. METHODS: We measured the plasma concentrations of digoxin-like immunoreactive substances (by a fluorescence polarisation immunoassay) and natriuretic peptides, aldosterone, renin, and antidiuretic hormone (by radioimmunoassay) in ten patients with aneurysmal subarachnoid haemorrhage, ten patients undergoing elective craniotomy for cerebral tumours, and 40 healthy controls of similar age and sex distribution. Samples were collected before surgery, 1 h, 4 h, and 12 h after surgery, then daily until 7 days postoperatively in the two groups of patients. FINDINGS: All patients with subarachnoid haemorrhage, but none of the tumour patients, showed increased urine output and urinary excretion of sodium (p = 0.018 for comparison of means of curves to 7 days). The patients with subarachnoid haemorrhage had much higher plasma concentrations of brain natriuretic peptide (BNP) than controls, on admission (mean 15.1 [SE 3.8] vs 1.6 [1.0] pmol/L, p < 0.001) and throughout the study period, accompanied by lower than normal aldosterone concentrations and normal plasma concentrations of atrial and C-type natriuretic peptides (ANP, CNP). The patients with tumours had similar plasma concentrations of ANP, BNP, and CNP to the controls. We did not detect digoxin-like immunoreactive substances in either group of patients. INTERPRETATION: Salt-wasting of central origin may induce hyponatraemia in patients with aneurysmal subarachnoid haemorrhage, possibly as a result of increased secretion of BNP with subsequent suppression of aldosterone synthesis.

Brain Neoplasms↗
PubMed1997

[The perioperative phase as a part of anesthesia. Tasks of the recovery room].

Historically, recovery rooms were established in order to reduce complications in the period immediately following surgery and anaesthesia, utilising staffing and equipment resources economically. To minimise the incidence of postoperative complications remains the main task of post anaesthesia care units (PACU). However, especially in hospitals with a high degree of surgical emergencies, the scope of tasks and procedures within the PACU has expanded. Facing restricted capacities in intensive therapy (ITU) and high dependency units (HDU) the PACU serves as a buffer; intensive care functions can be covered here until the patient can be admitted to an intensive care unit. In this context, the PACU also has a switch function; postoperatively, the patient is evaluated here and the level for further treatment determined: ITU, HDU, or normal ward. The PACU period can be utilised to improve the patient's condition (upgrade function) enabling continuation of treatment on a lower level (HDU instead of ITU, normal ward instead of HDU). This combination of buffer, switch and upgrade function is of special importance when ITU and HDU resources are limited. A new task for the PACU arises from efforts to optimise acute pain therapy; initial adjustment of continuous infusion systems according to the patients' needs can be performed here without additional staffing requirements. Finally, the PACU can be used preoperatively for "tune up" procedures in high risk patients. The basis for co-operation between anaesthetist and surgeon is the separation of responsibilities in combination with mutual trust. Accordingly, the anaesthetist is responsible for monitoring and maintenance of vital functions. Consequently, the anesthetist has a professional and organisational responsibility in the PACU. The surgeon can and must rely on notification whenever surgical complications may require his intervention. With increasing comorbidity of patients and complexity of surgical procedures the anaesthetist's responsibility in the immediate perioperative period gains a new quality. The number of surgical procedures requiring intraoperative intensive therapy from the anaesthetist is increasing; the delivery of anaesthesia becomes a background task during these operations. Thus, the anaesthetist becomes responsible for perioperative patient treatment in the operating room area which divides into three phases: preoperative "tune up" in the PACU (e.g.) haemodynamic optimisation, starting continuous regional anaesthesia techniques), anaesthesia and support of vital functions in the OR, and immediately postoperative treatment in the PACU.

Anesthesia↗
PubMed1997

[Spinal and regional anesthesia in bacteremia].

Bacteraemia and septicaemia are generally thought to be relative or absolute contraindications for central neural axis (CNA) blocks. Postulated mechanisms for haematogenous infection of the central nervous system (CNS) caused by subarachnoid or epidural puncture might be an accidental vessel puncture, a change of pressure in the subarachnoid space, and the induction of a "locus minoris resistentiae." Infectious complications of diagnostic lumbar puncture, spinal or epidural anaesthesia are very rare. Although in animals meningitis can be induced by subarachnoid puncture during bactaeremia, there is no study that proves an increased risk for bacteraemic patients. Transient bacteraemia is common, especially in urological and obstetrical-gynecological procedures that are often done in regional anaesthesia, but the incidence of infectious complications is low. This review investigates the few published cases in which a haematogenous infection of the CNS may have been caused by regional anaesthesia. Based on current knowledge, bacteraemia cannot be an absolute, but only a relative contraindication for CNA blocks. Antibiotic chemoprophylaxis should be given before the puncture and the patients must be closely followed after the anaesthesia, particularly for the development of spinal epidural abscess. Because of the possibly increased risk of infectious complications, informed consent should be obtained from the patient.

Anesthesia, Conduction↗
PubMed1997

Effects of sympathetic nerve blockade on vasoconstrictive properties of nitric oxide synthase inhibition in sheep.

OBJECTIVE: Inhibition of nitric oxide synthase causes intense vasoconstriction. This effect is thought to be dependent on sympathetic nerve activity. Thus, we investigated the vasoconstrictive effects of the nitric oxide synthase inhibitor NG-nitro-L-arginine methyl ester (L-NAME) in sheep, in which a reversible sympathetic block was established by thoracic epidural anesthesia. METHODS: Sheep (n = 11) were surgically prepared for chronic study. After at least 5 days of recovery, L-NAME was continuously administered and hemodynamics were monitored. This was done in sheep with and without sympathetic blockade in randomized order. RESULTS: The vasoconstrictive effects of L-NAME were similar in sheep with and without sympathetic blockade. CONCLUSION: The obtained results suggest that the vasoconstrictive properties of nitric oxide synthase inhibitors are independent of sympathetic tone.

Anesthesia, Epidural↗
PubMed1996

[Treatment reduction in intensive care. "Allowing the patient to die" by conscious withdrawal of medical procedures].

The conversion of an "attempt to treat" to "prolongation of dying" represents an important problem in modern intensive care. If the actual or presumed will of the patient is unknown, the physician has to decide about the extent of treatment in a paternalistic manner. In these difficult decisions the physician has to consider prognosis, and certainty of prognosis and has to carefully balance between the right to live and the right to die. This decision about the extent of therapy is a very personal medical activity and can be taken off the physician's shoulders by nobody. Consultation with other physicians involved, relatives, nurses and clergy, however, is mandatory, as a joint decision should be sought. If the situation is hopeless and further medical interventions are futile, then allowing the patient to die by therapy reductions is not only a possibility but a mandatory act of humanity. In that case it does not matter whether new treatment modalities are abandoned or whether already instituted medical measures are withdrawn. In clinical practice, however, the "fine tuning" of therapy reduction has to be tailored to the individual case and largely depends on prognostic certainty.

Child↗
PubMed1996

[Anxiolysis, sedation, and stress reduction following oral premedication with midazolam in adults. A comparison with dipotassium clorazepate and placebo].

Benzodiazepines are the most commonly used anxiolytic agents. Among the benzodiazepines, midazolam has the advantage of a short elimination half-life, which is especially useful in outpatient surgery. However, in contrast to other commonly prescribed benzodiazepines, such as chlorazepate dipotassium, oral premedication with midazolam has not been thoroughly investigated. Therefore, the present study was performed to compare anxiolysis, sedation and stress reduction with midazolam and clorazepate dipotassium in adults. METHODS. After IRB approval and informed consent had been obtained, 85 patients scheduled for breast biopsy were studied. The patients were chosen at random to receive either 7.5 mg midazolam (n = 29), 20 mg clorazepate dipotassium (n = 28) or placebo (n = 28) preoperatively. Before premedication, immediately prior to surgery and postoperatively in the recovery room, the following parameters were determined with visual analogue scales (VAS): "asthenia," "depression," oral salivation, muscle tension, motoric restlessness and sweating of the palms. In addition, anxiety (STAI-G-X-1, Spielberger), heart rate and arterial blood pressure were measured. Before patients underwent surgery, the degree of sedation was evaluated by the anaesthesiologist. RESULTS. Clorazepate dipotassium and midazolam both caused a reduction in anxiety as compared with the placebo (P < 0.05). Only clorazepate dipotassium reduced anxiety postoperatively (P < 0.05). Neither midazolam nor clorazepate dipotassium caused a reduction in "asthenia" and "depression." Midazolam was more effective in preventing increased blood pressure than clorazepate dipotassium and the placebo (P < 0.05). Furthermore, after premedication with midazolam, salivation, muscle tension, motoric restlessness and sweating of the palms remained stable, in contrast to the results after premedication using clorazepate dipotassium or placebo (P < 0.05). CONCLUSIONS. The anxiolytic effects of 7.5 mg midazolam and 20 mg clorazepate dipotassium were similar after oral application. However, the anxiolytic effect of midazolam is shorter-lived than that of clorazepate dipotassium. In contrast to clorazepate dipotassium, midazolam produced no increase in arterial blood pressure and stabilized oral salivation, production in the palms, muscle tension and motoric restlessness.

Adult↗