Pulse Oximetry PDF

Pulse Oximetry University Of AL - Mashreq MARIAM AYAD BSC. ANESTHESIA &ICU  Pulse Oximetry definition Features of the device This is a non-invasive measurement of 1. Cheap the arterial blood o...

Pulse Oximetry University Of AL - Mashreq MARIAM AYAD BSC. ANESTHESIA &ICU  Pulse Oximetry definition Features of the device This is a non-invasive measurement of 1. Cheap the arterial blood oxygen saturation at the 2. It is easy to operate. level of the arterioles. A continuous 3. It provides continuous and immediate oxygen saturation display of the oxygenation is achieved by values. a simple, accurate and rapid method. Uses The pulse oximeter is used to verify: 1. The presence of sufficient levels of oxygen in the blood. 2. The effectiveness of the heart in pumping oxygen to different parts of the body. Normal Pulse Oximetry Readings Normal lab values range between 95-100% Readings between 93% and 97% may be normal for some patients e.g, Chronic Obstructive Pulmonary Disease (COPD) Oxygen (at minimum) should be applied for readings below 92%, if less indicates the possibility of (hypoxia) in the body, or a lack of oxygen reaching the tissues of the body.  Components 1. A probe is positioned on the finger, 2. The case houses the toe, ear, lobe, or nose. Two light- microprocessor. There is a display of emitting diodes (LEDs) produce beams the oxygen saturation, pulse rate, and at red and infrared frequencies a plethysmographic waveform of (660 nm and 940 nm respectively) on the pulse. Alarm limits can be set for a one side and there is a sensitive low saturation value and both high photodetector on the other side. The and low pulse rates. LEDs operate in sequence at a rate of about 30 times per second. Mechanism of action: 1. The oxygen saturation is estimated by measuring the transmission of light, through a pulsatile vascular tissue bed(e.g. finger). 2. Constant tissues like skin, bones, and venous blood absorb a fixed amount of light, while the absorption varies due to arterial blood flow. 3. The sensor analyzes the transmitted light, calculating oxygen saturation based on light absorption at wavelengths of 660 and 940 nm. 4. A variable pitch beep provides an audible signal of changes in saturation. Problems in practice and safety features: 1. 4 Accurate within ±2% in the 70-100% range; readings Cabon monoxide poisoning (including smoking), below 70% are extrapolated. coloured nail varnish, intravenous injections of certain dyes (e.g. methylene blue, indocyanine green) and drugs responsible for the production of methaemoglobinaemia are all sources of error. 2 Hypoperfusion and severe peripheral vasoconstriction 5 affect the performance of the pulse oximeter. The device only measures oxygenation, not CO₂ elimination. 3 Probe sites must be checked regularly to avoid pressure sores; site changes are recommended every 2 hours for patients with poor circulation.  ADJUSTABLE PRESSURE LIMITING (APL) VALVE This is a valve which allows the exhaled gases and excess FGF to leave the breathing system. It does not allow room air to enter the breathing system. Also called expiratory valve, spill valve and relief valve.  Components 1. Three ports: the inlet, the patient and the exhaust ports. The latter can be open to the atmosphere or connected to the scavenging.system using a shroud 2. A lightweight disc rests on a knife-edge seating. The disc is held onto its seating by a spring. The tension in the spring, and therefore the valve’s.opening pressure, are controlled by the valve dial Advantages: 1. Controls airway pressure to Disadvantages prevent lung damage. 2. Adjustable according to the 1. Requires constant monitoring. patient’s needs. 2. Can be misadjusted. 3. Increases safety during 3. Relies on manual operation, manual ventilation. increasing the chance of error. 4. Helps control the exhalation 4. Not used in mechanical process. ventilation. thank you