{"id":2233,"date":"2015-04-14T16:33:01","date_gmt":"2015-04-14T16:33:01","guid":{"rendered":"http:\/\/opentextbc.ca\/clinicalskills\/?post_type=chapter&p=2233"},"modified":"2019-06-05T21:34:02","modified_gmt":"2019-06-05T21:34:02","slug":"5-2-pulse-oximetry-2","status":"publish","type":"chapter","link":"https:\/\/opentextbc.ca\/clinicalskills\/chapter\/5-2-pulse-oximetry-2\/","title":{"raw":"5.3 Pulse Oximetry","rendered":"5.3 Pulse Oximetry"},"content":{"raw":"Oxygen saturation, sometimes referred to as \u2018\u2018the fifth vital sign,\" should be checked by pulse oximetry in all breathless and acutely ill patients (British Thoracic Society, 2008). SpO2<\/sub> and the inspired oxygen concentration should be recorded on the observation chart together with the oximetry result. The other vital signs of\u00a0pulse, blood pressure, temperature, and respiratory rate should also be recorded in situations where supplemental oxygen is required.\r\n\r\nPulse oximetry is a painless, non-invasive method to monitor SpO2<\/sub>\u00a0intermittently and\u00a0continuously. The use of a pulse oximeter (see Figure 5.1) is indicated in patients who have, or are at risk for, impaired gaseous exchange or an unstable oxygen status.\r\n\r\n[caption id=\"attachment_3908\" align=\"aligncenter\" width=\"300\"]\"pulse<\/a> Figure 5.1 Pulse oximeter[\/caption]\r\n\r\nThe pulse oximeter is a probe\u00a0with a light-emitting diode (LED) that is attached to the\u00a0patient's\u00a0finger,\u00a0forehead, or ear.\u00a0Beams of red and infrared light are emitted from the LED, and the light wavelengths\u00a0are absorbed differently by the oxygenated and the deoxygenated hemoglobin (HgB) molecules.\u00a0The receiving sensor measures the amount of light absorbed by the oxygenated and deoxygenated Hgb in the arterial (pulsatile) blood. The more HgB that is saturated with oxygen, the higher the SpO2<\/sub>, which should normally measure above 95%.\r\n\r\nPulse oximeters have an indicator of signal strength\u00a0(such as\u00a0a bar graph, audible tone, waveform, or flashing light) to show how strong the receiving signal is. Measurements should be considered\u00a0inaccurate\u00a0if the signal strength is poor.\r\n\r\nPulse oximeters will also indicate heart rate by counting the number of pulsatile signals. To ensure accuracy, count\u00a0the patient\u2019s pulse\u00a0rate by taking the pulse and comparing it to the pulse\u00a0rate shown on the pulse oximeter.\r\n

Limitations<\/h2>\r\nThe most common cause of inaccuracy with pulse oximeters is motion artifact. Patient movement can\u00a0cause pulsatile venous flow to be\u00a0incorrectly measured as arterial pulsations, thus producing\u00a0an inaccurate oximetry and pulse-rate reading.\r\n\r\nAnother common cause of inaccuracy is poor peripheral perfusion. Poor peripheral perfusion can be caused by conditions such as hypothermia, peripheral vascular disease, vasoconstriction, hypotension, or peripheral edema (Perry, Potter, & Ostendorf, 2014). A forehead probe can be used for patients with decreased peripheral perfusion.\r\n\r\nConditions such as jaundice, as well as\u00a0intravascular dyes and carbon monoxide in the blood, can also influence oximetry readings.\u00a0Anemic patients with low Hgb may\u00a0have a normal SpO2<\/sub> reading, even though the available oxygen is not enough to meet the metabolic demands of the body.\u00a0Patients with elevated bilirubin concentrations may also have falsely low SpO2<\/sub>\u00a0readings (Howell, 2002).\r\n

Application of Pulse Oximetry<\/h2>\r\nIf measuring SpO2<\/sub> by attaching the\u00a0probe to a finger or toe, check the radial or pedal\u00a0pulse and capillary refill of the finger or toe\u00a0you plan to use. If the patient's extremities are cold, you could\u00a0try to warm his or her hands in yours, or apply warm\u00a0towels to improve perfusion.\r\n\r\nThe patient\u2019s finger or toe should be\u00a0clean and dry. Check that the patient does not have artificial\u00a0nails or\u00a0nail polish, as both will influence the light transmission and should, therefore, be removed before applying pulse oximetry.\r\n\r\nCheck that the probe is positioned properly so that optical shunting (when light from the transmitter passes directly into the receiver without going through the finger) does not occur.\r\n\r\nBright ambient light may also affect the\u00a0accuracy of pulse oximetry readings.\r\n

Hazards of Pulse Oximetry<\/h2>\r\nPulse oximetry is generally considered to be a safe procedure.\u00a0However, tissue injury may occur at the measuring site as a result of probe misuse.\u00a0Pressure sores or burns\u00a0are possible effects of prolonged application (>2 hours).\r\n<\/table>
\r\n

Critical Thinking Exercises<\/p>\r\n\r\n<\/header>\r\n

\r\n
    \r\n\t
  1. You are checking your patient's\u00a0SpO2 <\/sub>but the\u00a0signal\u00a0strength on the pulse oximeter is poor. What would be your next steps?<\/li>\r\n\t
  2. Your patient has been admitted with a diagnosis of carbon monoxide poisoning with an\u00a0SpO2\u00a0<\/sub>of 98%. What does this reading tell you?<\/li>\r\n<\/ol>\r\n<\/div>","rendered":"

    Oxygen saturation, sometimes referred to as \u2018\u2018the fifth vital sign,” should be checked by pulse oximetry in all breathless and acutely ill patients (British Thoracic Society, 2008). SpO2<\/sub> and the inspired oxygen concentration should be recorded on the observation chart together with the oximetry result. The other vital signs of\u00a0pulse, blood pressure, temperature, and respiratory rate should also be recorded in situations where supplemental oxygen is required.<\/p>\n

    Pulse oximetry is a painless, non-invasive method to monitor SpO2<\/sub>\u00a0intermittently and\u00a0continuously. The use of a pulse oximeter (see Figure 5.1) is indicated in patients who have, or are at risk for, impaired gaseous exchange or an unstable oxygen status.<\/p>\n

    \"pulse<\/a>
    Figure 5.1 Pulse oximeter<\/figcaption><\/figure>\n

    The pulse oximeter is a probe\u00a0with a light-emitting diode (LED) that is attached to the\u00a0patient’s\u00a0finger,\u00a0forehead, or ear.\u00a0Beams of red and infrared light are emitted from the LED, and the light wavelengths\u00a0are absorbed differently by the oxygenated and the deoxygenated hemoglobin (HgB) molecules.\u00a0The receiving sensor measures the amount of light absorbed by the oxygenated and deoxygenated Hgb in the arterial (pulsatile) blood. The more HgB that is saturated with oxygen, the higher the SpO2<\/sub>, which should normally measure above 95%.<\/p>\n

    Pulse oximeters have an indicator of signal strength\u00a0(such as\u00a0a bar graph, audible tone, waveform, or flashing light) to show how strong the receiving signal is. Measurements should be considered\u00a0inaccurate\u00a0if the signal strength is poor.<\/p>\n

    Pulse oximeters will also indicate heart rate by counting the number of pulsatile signals. To ensure accuracy, count\u00a0the patient\u2019s pulse\u00a0rate by taking the pulse and comparing it to the pulse\u00a0rate shown on the pulse oximeter.<\/p>\n

    Limitations<\/h2>\n

    The most common cause of inaccuracy with pulse oximeters is motion artifact. Patient movement can\u00a0cause pulsatile venous flow to be\u00a0incorrectly measured as arterial pulsations, thus producing\u00a0an inaccurate oximetry and pulse-rate reading.<\/p>\n

    Another common cause of inaccuracy is poor peripheral perfusion. Poor peripheral perfusion can be caused by conditions such as hypothermia, peripheral vascular disease, vasoconstriction, hypotension, or peripheral edema (Perry, Potter, & Ostendorf, 2014). A forehead probe can be used for patients with decreased peripheral perfusion.<\/p>\n

    Conditions such as jaundice, as well as\u00a0intravascular dyes and carbon monoxide in the blood, can also influence oximetry readings.\u00a0Anemic patients with low Hgb may\u00a0have a normal SpO2<\/sub> reading, even though the available oxygen is not enough to meet the metabolic demands of the body.\u00a0Patients with elevated bilirubin concentrations may also have falsely low SpO2<\/sub>\u00a0readings (Howell, 2002).<\/p>\n

    Application of Pulse Oximetry<\/h2>\n

    If measuring SpO2<\/sub> by attaching the\u00a0probe to a finger or toe, check the radial or pedal\u00a0pulse and capillary refill of the finger or toe\u00a0you plan to use. If the patient’s extremities are cold, you could\u00a0try to warm his or her hands in yours, or apply warm\u00a0towels to improve perfusion.<\/p>\n

    The patient\u2019s finger or toe should be\u00a0clean and dry. Check that the patient does not have artificial\u00a0nails or\u00a0nail polish, as both will influence the light transmission and should, therefore, be removed before applying pulse oximetry.<\/p>\n

    Check that the probe is positioned properly so that optical shunting (when light from the transmitter passes directly into the receiver without going through the finger) does not occur.<\/p>\n

    Bright ambient light may also affect the\u00a0accuracy of pulse oximetry readings.<\/p>\n

    Hazards of Pulse Oximetry<\/h2>\n

    Pulse oximetry is generally considered to be a safe procedure.\u00a0However, tissue injury may occur at the measuring site as a result of probe misuse.\u00a0Pressure sores or burns\u00a0are possible effects of prolonged application (>2 hours).<\/p>\n

    \n
    \n

    Critical Thinking Exercises<\/p>\n<\/header>\n

    \n
      \n
    1. You are checking your patient’s\u00a0SpO2 <\/sub>but the\u00a0signal\u00a0strength on the pulse oximeter is poor. What would be your next steps?<\/li>\n
    2. Your patient has been admitted with a diagnosis of carbon monoxide poisoning with an\u00a0SpO2\u00a0<\/sub>of 98%. What does this reading tell you?<\/li>\n<\/ol>\n<\/div>\n<\/div>\n","protected":false},"author":5,"menu_order":3,"template":"","meta":{"pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":[],"pb_section_license":""},"chapter-type":[],"contributor":[],"license":[],"class_list":["post-2233","chapter","type-chapter","status-publish","hentry"],"part":2226,"_links":{"self":[{"href":"https:\/\/opentextbc.ca\/clinicalskills\/wp-json\/pressbooks\/v2\/chapters\/2233","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/opentextbc.ca\/clinicalskills\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/opentextbc.ca\/clinicalskills\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/opentextbc.ca\/clinicalskills\/wp-json\/wp\/v2\/users\/5"}],"version-history":[{"count":26,"href":"https:\/\/opentextbc.ca\/clinicalskills\/wp-json\/pressbooks\/v2\/chapters\/2233\/revisions"}],"predecessor-version":[{"id":9915,"href":"https:\/\/opentextbc.ca\/clinicalskills\/wp-json\/pressbooks\/v2\/chapters\/2233\/revisions\/9915"}],"part":[{"href":"https:\/\/opentextbc.ca\/clinicalskills\/wp-json\/pressbooks\/v2\/parts\/2226"}],"metadata":[{"href":"https:\/\/opentextbc.ca\/clinicalskills\/wp-json\/pressbooks\/v2\/chapters\/2233\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/opentextbc.ca\/clinicalskills\/wp-json\/wp\/v2\/media?parent=2233"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/opentextbc.ca\/clinicalskills\/wp-json\/pressbooks\/v2\/chapter-type?post=2233"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/opentextbc.ca\/clinicalskills\/wp-json\/wp\/v2\/contributor?post=2233"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/opentextbc.ca\/clinicalskills\/wp-json\/wp\/v2\/license?post=2233"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}