Best practice & research. Clinical anaesthesiology
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Best Pract Res Clin Anaesthesiol · Jun 2009
ReviewIsotonic and hypertonic crystalloid solutions in the critically ill.
Disorders of fluid and electrolyte balance in the critically ill are volume-related, compositional, or both. Targeting 'normal' values for plasma volume, osmolality and electrolytes might not be optimal in conditions as diverse as intracranial trauma/haemorrhage, hepatic encephalopathy, abdominal hypertension, or major surgery, because a hyperosmolar state seems to favourably affect tissue (brain and intestinal) oedema formation. ⋯ Crystalloid resuscitation is superior to vasopressors in shock associated with blunt trauma, and is at least not inferior to colloids in septic shock. Traditional rules of thumb indicating the need for three to four times the amount of crystalloids for the plasma volume to be replaced are probably erroneous and might have contributed to association of overly aggressive crystalloid resuscitation with poor outcome.
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Peri-operative fluid therapy continues to be an exercise in empiricism, with nagging questions about efficacy and complications. Pharmacokinetics is used for studying the time dependency of administered drugs. ⋯ This could possibly allow for more rational design of intravenous fluid paradigms to improve clinical fluid therapy. This chapter briefly summarizes currently accepted principles of fluid therapy, discusses the general approach to kinetic analysis of fluid therapy, reviews currently available data defining kinetic responses to fluid therapy, and speculates about future applications of this approach.
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Best Pract Res Clin Anaesthesiol · Jun 2009
ReviewInfluence of fluid therapy on the haemostatic system of intensive care patients.
Haemostatic alterations associated with the use of fluids are related to non-specific dilutional effects and colloid-specific effects, such as acquired von Willebrand syndrome, inhibition of platelet function and fibrin polymerization. Judging by currently available evidence, dextran, hetastarch and pentastarch have a more pronounced impact than tetrastarch, gelatin and albumin. In patients with hypocoagulability, tetrastarch appears to be a suitable volume expander due to its high safety index and volume efficacy. ⋯ Dextrans are potent anticoagulants with a high risk for adverse reactions. Albumin has negligible effects on haemostasis, but low volume efficacy and costs limit the use of a blood product as a routine volume replacement fluid. To avoid potential acidosis-induced changes in haemostasis, plasma-adapted carrier solutions may be used instead of saline-based solutions.