Blood substitutes. Haemoglobin therapeutics in clinical practice. (25/1252)

Early approaches to the development of oxygen carriers involved the use of stroma-free hemoglobin solutions. These solutions did not require blood typing or crossmatching and could be stored for long periods. In addition, a variety of methods have been developed in chemically modifying and stabilizing the hemoglobin molecule. Several hemoglobin therapeutics are now in clinical trials as temporary alternatives to blood or as therapeutic agents for ischemia. The various hemoglobin products under development are derived from three principal sources: human, bovine and genetically engineered hemoglobin. Diaspirin cross-linked hemoglobin (DCLHb), administered at doses ranging from approximately 20-1000 ml, has been investigated in a number of clinical trials in patients undergoing orthopedic, abdominal aortic repair, major abdominal surgery, cardiac surgery and in critically ill patients with septic shock. In several studies, DCLHb was effective in avoiding the transfusion. However, Baxter Healthcare Corporation (Chicago, Illinois, USA) stopped the development of DCLHb after two unsuccessful trials in trauma patients. Bovine polymerized hemoglobin has also been extensively studied. Several phase II and phase III trials have been performed with this product in hemorrhagic surgery, cardiac surgery and vascular surgery, but data have not yet been published. Hemoglobin therapeutics could provide an important new option as an alternative to blood transfusion. Furthermore, they may be able to provide an immediate on-site replacement for traumatic blood loss, prevent global ischemia and organ failure, treat focal ischemia, and provide effective hemodynamic support for septic shock-induced hypotension.  (+info)

Determinants of blood pH in health and disease. (26/1252)

An advanced understanding of acid-base physiology is as central to the practice of critical care medicine, as are an understanding of cardiac and pulmonary physiology. Intensivists spend much of their time managing problems related to fluids, electrolytes, and blood pH. Recent advances in the understanding of acid-base physiology have occurred as the result of the application of basic physical-chemical principles of aqueous solutions to blood plasma. This analysis has revealed three independent variables that regulate pH in blood plasma. These variables are carbon dioxide, relative electrolyte concentrations, and total weak acid concentrations. All changes in blood pH, in health and in disease, occur through changes in these three variables. Clinical implications for these findings are also discussed.  (+info)

Noninvasive positive pressure ventilation as treatment for acute respiratory failure in critically ill patients. (27/1252)

Our current state of knowledge on noninvasive positive pressure ventilation (NPPV) and technical aspects are discussed in the present review. In patients with chronic obstructive pulmonary disease, NPPV can be considered a valid therapeutic option to prevent endotracheal intubation. Evidence suggests that, before eventual endotracheal intubation, NPPV should be considered as first-line intervention in the early phases of acute exacerbation of chronic obstructive pulmonary disease. Small randomized and non-randomized studies on the application of NPPV in patients with acute hypoxaemic respiratory failure showed promising results, with reduction in complications such as sinusitis and ventilator-associated pneumonia, and in the duration of intensive care unit stay. The conventional use of NPPV in hypoxaemic acute respiratory failure still remains controversial, however. Large randomized studies are still needed before extensive clinical application in this condition.  (+info)

Abdominal compartment syndrome. (28/1252)

Intra-abdominal hypertension (IAH) associated with organ dysfunction defines the abdominal compartment syndrome (ACS). Elevated intra-abdominal pressure (IAP) adversely impacts pulmonary, cardiovascular, renal, splanchnic, musculoskeletal/integumentary, and central nervous system physiology. The combination of IAH and disordered physiology results in a clinical syndrome with significant morbidity and mortality. The onset of the ACS requires prompt recognition and appropriately timed and staged intervention in order to optimize outcome. The history, pathophysiology, clinical presentation, and management of this disorder is outlined.  (+info)

Does perfluorocarbon deoxygenate during partial liquid ventilation? (29/1252)

Perfluorocarbons accumulate in the dependent regions of the lungs, which may result in regional hypoxia if ventilation with oxygen is insufficient to oxygenate the dependent perfluorocarbon-filled alveoli. In this issue of Critical Care, Max et al present data that demonstrate a decrease in arterial oxygen tension (PaO2) at 30 min compared to that observed at 5 min after administration of FC 3280. These data suggest failure of on-going ventilation/oxygenation to support the initial increase in PaO2 attributed to the oxygen dissolved in the administered perfluorocarbon. Studies such as this one demonstrate that development of the optimal partial liquid ventilation (PLV) technique is ongoing.  (+info)

Hemofiltration in sepsis: where do we go from here? (30/1252)

Hemofiltration as an adjunct to therapy for sepsis is now 10 years old. Despite early successes and significant theoretical advantages, the treatment remains experimental. Although feasibility has been established, efficacy has proved to be much more difficult. Clinical as well as technical difficulties remain important considerations to future studies. These issues are discussed and the brief history of hemofiltration in sepsis is reviewed.  (+info)

Weaning from mechanical ventilation. (31/1252)

Practice guidelines on weaning should be based on the results of several well-designed randomized studies performed over the last decade. One of those studies demonstrated that immediate extubation after successful trials of spontaneous breathing expedites weaning and reduces the duration of mechanical ventilation as compared with a more gradual discontinuation of ventilatory support. Two other studies showed that the ability to breathe spontaneously can be adequately tested by performing a trial with either T-tube or pressure support of 7 cmH2O lasting either 30 or 120 min. In patients with unsuccessful weaning trials, a gradual withdrawal for mechanical ventilation can be attempted while factors responsible for the ventilatory dependence are corrected. Two randomized studies found that, in difficult-to-wean patients, synchronized intermittent mandatory ventilation (SIMV) is the most ineffective [corrected] method of weaning.  (+info)

Life-threatening brain failure and agitation in the intensive care unit. (32/1252)

The modern intensive care unit (ICU) has evolved into an area where mortality and morbidity can be reduced by identification of unexpected hemodynamic and ventilatory decompensations before long-term problems result. Because intensive care physicians are caring for an increasingly heterogeneous population of patients, the indications for aggressive monitoring and close titration of care have expanded. Agitated patients are proving difficult to deal with in nonmonitored environments because of the unpredictable consequences of the agitated state on organ systems. The severe agitation state that is associated with ethanol withdrawal and delirium tremens (DT) is examined as a model for evaluating the efficacy of the ICU environment to ensure consistent stabilization of potentially life-threatening agitation and delirium.  (+info)