Pulse oximetry

There are a number of equations and definitions associated with the principles behind the working of the pulse oximeter. 

The absorbance of light passing through a medium is proportional to the concentration of the medium. 

Draw a line that passes through the origin and which rises steadily as C increases. The slope of the line is dependent upon the molar extinction coefficient (/ ), which is a measure of how avidly the medium absorbs light, and by the path length (L). Note that if emergent light (1) is plotted on the y axis instead of absorbance, the curve should be drawn as an exponential decline. 

Both laws are often presented together to give the following equation, known as the Beer-Lambert law, which is a negative exponential equation of the form 

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In massive PE, the patient may appear cyanotic and may become hypotensive. In such cases, oxygen saturation by pulse oximetry or arterial blood gas will likely indicate that the patient is hypoxic. 

Hypoxia and respiratory or metabolic acidosis are common in patients with SE. Therefore, pulse oximetry and ABG measurements are useful to assess the patient s respiratory... 

Mendelson Y., Ochs B.D., Noninvasive pulse oximetry utilizing skin reflectance photoplethysmography, IEEE Trans. Biomed. Eng. 1988 BME-35 798. 

Dildy G., Clark S., Loucks C., Intrapartum fetal pulse oximetry Past, present, and future, American Journal of Obstetrics and Gynecology 1996 175 1. 

Cardiopulmonary support must be instituted and adjusted rapidly. Electrocardiogram (ECG) monitoring, continuous pulse oximetry, urine flow monitoring, and automated blood pressure recording are necessary. Peripheral or femoral arterial catheters may be used for continuous assessment of arterial pressure. 

Leukocytosis with a predominance of polymorphonuclear cells Low oxygen saturation on arterial blood gas or pulse oximetry... 

Peak expiratory flow (PEF) and FEVj are less than 50% of normal predicted values. Pulse oximetry reveals decreased arterial oxygen and 02 saturations. The best predictor of outcome is early response to treatment as measured by improvement in FEVj at 30 minutes after inhaled /12-agonists. 

Oxygen saturations can be easily monitored continuously with pulse oximetry. For young children and adults, pulse oximetry, lung auscultation, and observation for supraclavicular retractions is useful. 

Kumar A, Chawla R, Ahuja S, et al. 1990. Nitrobenzene poisoning and spurious pulse oximetry. Anaesthesia 45 949-951. 

The ECT unit should be staffed by experienced professionals trained in the use of the procedure and in the care of an unconscious patient, including measures for intravenous access, monitoring of blood pressure, pulse oximetry, and EKG (Gaines and Rees, 1992). The ECT team usually includes a psychiatrist, an anesthesiologist, and a nurse. 

McMorrow RC, Mythen MG. Pulse oximetry. Current Opinion in Critical Care 2006, 12, 269-271. 

Jubran A. Pulse oximetry. Intensive Care Medicine 2004, 30, 2017-2020. 

Mendelson Y. Pulse oximetry—theory and applications for noninvasive monitoring. Clinical Chemistry 1992, 38, 1601-1607. 

Severinghaus JW, Kelleher JF. Recent developments in pulse oximetry. Anesthesiology 1992, 76, 1018-1038. 

Bowes WA, Corke BC, Hulka J. Pulse oximetry a review of the theory, accuracy and clinical applications. Obstetrics and Gynecology 1989, 74, 541-546. 

Kelleher JF. Pulse oximetry. Journal of Clinical Monitoring 1989, 5, 37-62. 

Interpretation of this patient s pulse oximetry and arterial gases is shown in Table A3.3. 

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