Der Anaesthesist
-
After rapid changes in transfusion practice over the past few years, blood conservation techniques have become standard in modern perioperative management. As a result, the amount of homologous blood products transfused has been markedly reduced in some types of surgical procedures. Provided that skillful surgical technique is applied and the use of blood products is restricted, autologous transfusion techniques (predonation of autologous blood, preoperative plasmapheresis, acute normovolaemic haemodilution, and intra- and postoperative blood salvage) can be performed with an acceptable risk for patients. ⋯ If storage is necessary, autologous blood products should be preparated like homologous products. The feasibility of predonation and retransfusion of autologous blood in patients with infectious diseases like hepatitis or acquired immune deficiency syndrome and the amount of labaratomy testing are still under discussion. Although blood conservation programs are time-consuming and more expensive, they reduce the various risks of using homologous blood products.
-
On the subject of natriuretic peptides there is a great deal of controversy, and intensive research efforts have been made studying their effects on electrolyte homeostasis. In the early 1980s, a peptide that caused diuresis, natriuresis, and had a relaxant effect on vascular smooth muscle was discovered independently by several groups. This was the breakthrough for the identification of natriuretic peptides, followed by the characterisation of the amino-acid sequences of several species. ⋯ These results were encouraging for the use of URO in clinical trials as a tool to prevent acute renal failure (ARF) in patients following heart transplantation and for treatment of incipient ARF in patients following liver transplantation. Summarising the results of these two studies, URO represents a new approach for not only prevention, but also for treatment of ARF following organ transplantation. This opens up new possibilities for the treatment of ARF of other origins in intensive care medicine.
-
Preventive strategies aim to reduce gastric acidity (H2-antagonists, antacids), to strengthen mucosal defence mechanisms (sucralfate, antacids, pirenzepine) and to normalize gastric mucosal microcirculation (sucralfate, pirenzepine). Thus, the most important prophylactic measure is an optimized emergency and ICU regime aiming to improve oxygenation and microcirculation. All specific drugs used for stress ulcer prophylaxis have been shown to be effective in prospective controlled studies. ⋯ The most important adverse effect of stress ulcer prophylaxis is nosocomial pneumonia due to gastric alkalinization. This may occur in long-term ventilated patients with a gastric pH > 4 and may account for up to 50% of all nosocomial pneumonias in certain groups of patients. Mortality is not influenced by antacids or H2-antagonists, while sucralfate has been shown to reduce mortality, most probably by inhibition of bacterial translocation.
-
Although the attempts to develop an oxygen-carrying alternative to red blood cells (RBC) have spanned the last 100 years, it has proven difficult to develop a clinically useful haemoglobin-based oxygen carrier. Four major problems have been shown to compromise the use of haemoglobin outside the RBC as an oxygen carrier: (1) the increased oxygen affinity due to the loss of 2,3-diphosphoglycerate; (2) dissociation into dimers and monomers with consequent renal and capillary loss of hemoglobin; (3) insufficient concentrations of prepared solutions under iso-oncotic conditions, and thereby reduced oxygen-carrying capacity; and (4) toxicity. Most of these limitations have been overcome by different modifications of haemoglobin, including pyridoxylation, intra- and intermolecular cross-linking, polymerisation, liposome encapsulation, conjugation to inert macromolecules, and genetic engineering. ⋯ Based on promising and reproducible results obtained from animal studies, clinical phase I and II trials with newer haemoglobin solutions have been started in the United States. Substantial knowledge has been gained in the development, production, and evaluation of haemoglobin-based oxygen carriers during the past years. It will probably not take another century before oxygen-carrying RBC substitutes will become available for clinical use.
-
In order to assess the significance of drug levels measured in clinical and forensic toxicology as well as for therapeutic drug monitoring (TDM), it is essential that good collections of data are readily available. For more than 400 frequently used drugs therapeutic and, if data were available, toxic and fatal plasma concentrations as well as elimination half-lives were compiled in a table including, e.g., hypnotics like barbiturates and benzodiazepines, neuroleptics, antidepressants, sedatives, analgesics, anti-inflammatory agents, antihistamines, anti-epileptics, beta-adrenergic antagonists, antibiotics (penicillins, cephalosporins, aminoglycosides, gyrase inhibitors), diuretics, calcium-channel blockers, cardiac glycosides, anti-arrhythmics, anti-asthmatics, angiotensin converting enzyme inhibitors, opioid agonists, and local anaesthetics. ⋯ The range of (or single) half-life values given for each drug are chosen to represent the terminal log-linear phase at most. In addition to the assessment of significance of drug levels for the therapeutic monitoring of patients, this list can assist the diagnostic assessment in cases of intoxication.