PubMed Health⌕ Search

Biomedical subjects

J U Bleyl

Publications and source records attributed to J U Bleyl.

9 recordsLinked to original sources
PubMed2000

[From isoflurane to perfluorohexane? Perfluorocarbons--therapeutic strategies in acute lung failure].

The introduction of Perfluorochemicals into medicine and especially into the treatment of severe lung injury is a fascinating scientific task. Many recall the famous experiments from Clark et al. in 1966 when he demonstrated "liquidventilation with perfluorocarbons" in the mammal species for the first time. After this hallmark, perfluorocarbons were subsequently introduced in research of acute lung injury by the techniques of Total- and Partial-Liquid-Ventilation (TLV; PLV). Perfluorocarbons (saturated organofluorids) have unique chemical and physical properties which made them attractive substances for intraalveolar application. The strong C-F bindings in the perfluorocarbon molecules are responsible for their chemical stability, biochemical inertness, high capacity to dissolve respiratory gases, low surface tension and high vapor pressures. Furthermore, the high density of the PFC lead to radio-opacity and their distribution to dependent lung areas. The efficacy of PFC liquid, applied by TLV/PLV has been demonstrated in numerous animal studies using different models of acute lung injury. Currently, several mechanisms of action of perfluorocarbon fluids in acute lung injury are discussed: recruitment of atelectatic alveoli, prevention of endexpiratory collapse of alveoli ("liquid PEEP"), redistribution of perfusion, oxygen transport, surfactant like effects and decrease of inflammation. Since total liquid ventilation has been used only in experimental models of lung injury, partial liquid ventilation has been introduced successfully into clinical trials (phase I-II). However, the results of the first randomised, controlled study of PLV in 90 adult patients suffering from severe respiratory failure (ALI/ARDS) showed no differences between PLV and conventional treatment. Furthermore, the instillation of relatively large amounts of liquid into the lungs poses several technical challenges and may be associated with complications such as liquithoraces, pneumothoraces and hypoxia. Since mammal lungs are evolutionary specialised to gas exchange using atmospheric oxygen, the application of liquids, even if they transport respiratory gases very well is not physiologic. To overcome these unwanted side effects, we developed a technique of perfluorocarbon vaporisation in analogy to the application of inhalation anaesthetic agents. After resolving some technical issues, this application technique was used successfully in an animal model of acute lung injury. Vaporisation of perfluorohexane in a concentration of 18 Vol.% of inspired gas improved significantly oxygenation and lung compliance. Though these results are promising, mechanisms of action, dose-efficacy relation, surfactant-perfluorocarbon interaction or anti-inflammatory effects of vaporised perfluorohexane are still unclear. These questions need to be clarified before this technique can be applied clinically. However, the inhalation of vapor, a technique already familiar to anaesthesiologists should avoid risks of large amounts of fluids in the bronchoalveolar space. Furthermore, this technique can be administered by established anaesthetic equipment with the advantage of exact dosing, continuous monitoring, and demand application in a way near to clinical routine.

Anesthetics, Inhalation↗
PubMed2000

Hemodynamic effects of hypertonic hydroxyethyl starch 6% solution and isotonic hydroxyethyl starch 6% solution after declamping during abdominal aortic aneurysm repair.

Fluid resuscitation with hypertonic hydroxyethyl starch solutions (HES) is effective in haemorrhagic shock due to the rapid mobilisation of fluids into the intravascular compartment. Declamping of the abdominal aorta with acute redistribution of blood into the vessels of the lower body half causes declamping-induced hypotension. Usually large amount of fluids or vasopressors are necessary to restore hemodynamic stability. Therefore, infusion of a hypertonic colloid solution may be an attractive option to achieve hemodynamic stability. This study was conducted to determine the amount of fluid of either hypertonic HES (HES 6%;7.2% NaCl) or isotonic HES (HES 6%;0.9% NaCl) needed to attain best wedge pressure (PCWP) cardiac index (CI) relation after declamping. Thirty-two high-risk patients undergoing elective abdominal aneurysm resection were enrolled in a prospective, randomised, double blinded study. The individual optimised PCWP/CI relation was determined after induction of anaesthesia. After declamping, both solutions were titrated in small boluses of 100 mL until the previously determined best wedge was reached. The amount of fluid after declamping was significantly reduced in the hypertonic HES- group 162 mL vs. 265 mL in the control group (P < 0.05). Resuscitation time was shortened, and cardiac index was slightly higher in the treatment group. The use of hypertonic HES-solution after aortic declamping led to a significant reduction of fluids necessary to attain optimised PCWP/CI relation. In this clinical trial with moderate blood loss in high-risk patients, hypertonic HES applied in a titrated fashion restored hemodynamic stability faster and without volume overload.

Aged↗
PubMed1999

[Combined anesthesia procedures].

The additive properties of general and regional anesthetic techniques are brought together in combined anesthesia to minimise side effects of the individual techniques. Despite a wide experience with both used as single anesthetic techniques, no definite recommendations regarding indications, general contraindications and procedure exist for their combination. Beneficial effects on haemodynamics, respiratory function, intestinal motility and postoperative stress response have been demonstrated for a combination of general anesthesia and thoracic epidural anesthesia (TEA). In addition TEA is favourable in the management of postoperative pain, which has advantageous effects on convalescence especially in a high risk patient group. Nevertheless, until now no reduction of perioperative morbidity and mortality has been demonstrated. Since the combination of two anesthesia techniques theoretically increases the rate of complication, the expected benefit for the patient must predominate. To estimate the risks and benefits of combined anesthesia, the anesthesiologist must be familiar with each single method, as well as with the synergistic effects of both techniques in order to evaluate the individual indication.

Anesthesia, Conduction↗
PubMed1999

Vaporized perfluorocarbon improves oxygenation and pulmonary function in an ovine model of acute respiratory distress syndrome.

BACKGROUND: Perfluorocarbon liquids are being used experimentally and in clinical trials for the treatment of acute lung injury. Their resemblance to inhaled anesthetic agents suggests the possibility of application by vaporization. The authors' aim was to develop the technical means for perfluorocarbon vaporization and to investigate its effects on gas exchange and lung function in an ovine model of oleic acid-induced lung injury. METHODS: Two vaporizers were calibrated for perfluorohexane and connected sequentially in the inspiratory limb of a conventional anesthetic machine. Twenty sheep were ventilated in a volume controlled mode at an inspired oxygen fraction of 1.0. Lung injury was induced by intravenous injection of 0.1 ml oleic acid per kilogram body weight. Ten sheep were treated with vaporized perfluorohexane for 30 min and followed for 2 h; 10 sheep served as controls. Measurements of blood gases and respiratory and hemodynamic parameters were obtained at regular intervals. RESULTS: Vaporization of perfluorohexane significantly increased arterial oxygen tension 30 min after the end of treatment (P < 0.01). At 2 h after treatment the oxygen tension was 376+/-182 mmHg (mean +/- SD). Peak inspiratory pressures (P < 0.01) and compliance (P < 0.01) were significantly reduced from the end of the treatment interval onward. CONCLUSION: Vaporization is a new application technique for perfluorocarbon that significantly improved oxygenation and pulmonary function in oleic acid-induced lung injury.

Animals↗
PubMed1996

Oxygenation of dog liver transplants as an early indicator of graft failure.

This study examines the potential value of liver oxygenation as a predictor of early graft function. pO2 measurements were performed on 10 pairs of beagle (donor) and foxhound (recipient) dogs during pentobarbital anesthesis. Two different explantation techniques were used: complete preparation and dissection before perfusion and explantation (group A) or rapid perfusion and explantation with detailed preparation of the liver and dissection of vessels ex situ after explantation (group B). In both groups, the technique of liver perfusion with 1,000 ml arterial and 500 ml portovenous application of ice-cold UW solution was equal. Local oxygen partial pressure values were obtained polarographically with miniaturized needle electrodes. The liver oxygenation directly after laparotomy was comparable in both groups (median values around 54 mm Hg). Prior to the infusion of UW solution, a reduction of the tissue oxygenation values to 24 mm Hg was observed in group A (p < 0.01 compared to postlaparotomy values). In group B, limited preexplantation surgical dissection resulted in a reduced pO2 decline to 42 mm Hg (n.s.). After transplantation, the reduced tissue oxygenation persisted in the livers of the dogs which were completely dissected in situ (group B) as compared to the preexplantation recipient and the donor liver before instrumentation (p < 0.01). In contrast, rapidly perfused livers again exhibited only an insignificant reduction of tissue oxygenation following transplantation. Survival correlated linearly with the liver oxygenation within the observation time after transplantation (p < 0.01). A significant survival advantage was found for the rapid perfusion technique (p < 0.05). We conclude that the tissue oxygenation might provide valuable information on early graft function.

Animals↗