Current opinion in critical care
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Pulse oximetry is now a ubiquitous and essential tool of modern medicine, and while it is a relatively recent invention, the technology has rapidly matured since the first commercially available oximeters were introduced in the 1970s. This review seeks to provide an overview of the basic physical operation of the probe and discuss its limitations, sources of error and some current advances in the use of multi-wavelength probes. ⋯ The pulse oximeter, like any basic tool, must be used properly. There is considerable misunderstanding and lack of education among junior clinicians as to the use and interpretation of pulse oximeters. The introduction of the pulse oximeter has demonstrated a cost saving, although the cost-benefit of new multi-wavelength probes remains unproven.
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Tissue hypoperfusion is a common pathophysiologic process leading to multiple organ dysfunction and death. Increases in tissue PCO2 can reflect an abnormal oxygen supply to the cells, so that monitoring tissue PCO2 by the use of gastric or sublingual capnometry may help identify circulatory abnormalities and guide their correction. This review provides an update on these technologies. ⋯ Gastric tonometry was proposed for regional PCO2 monitoring, but it is prone to a number of technical limitations. Sublingual capnometry could offer a valuable alternative for tissue PCO2 monitoring in clinical practice, representing a simple, noninvasive method to monitor tissue perfusion and titrate therapeutic interventions in critically ill patients.
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Curr Opin Crit Care · Jun 2006
ReviewRadiographic measures of intravascular volume status: the role of vascular pedicle width.
A valid, low-cost, high-yield instrument to assess intravascular volume status in critically ill patients does not exist. The portable chest X-ray is a common part of any intensivist's or chest clinician's daily rounds. ⋯ Vascular pedicle width measurement using a standardized approach to daily chest X-ray interpretation represents untapped potential for improving the non-invasive assessment of volume status in critically ill patients.
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Mixed venous and central venous oxygen saturations reflect the balance between oxygen requirement and oxygen delivery, and thus may be used to assess the adequacy of tissue oxygenation. This review discusses recent data on the impact of using venous oximetry by obtaining mixed venous oxygen saturation or central venous oxygen saturation as useful monitoring parameters in critically ill patients. ⋯ Early goal-directed therapy should be implemented in the initial resuscitation of septic patients. Central venous saturation may have prognostic significance following major surgery. Further evaluation of peri-operative trends in central venous saturation is required. Measurement of central venous oxygen saturation can easily be applied in intensive care unit patients and offers a useful, indirect indicator for the adequacy of tissue oxygenation.
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This review will summarize the available data regarding the haemodynamic changes occurring following cardiac arrest in humans and animal models. ⋯ Recent studies have provided important insights into the haemodynamics of cardiac arrest and of cardiopulmonary resuscitation which may inform more effective strategies for the management of cardiac arrest in the future.