Pulse Oximetry for Basic EMTs (3 hours - Basic level)


Course Format:This will be a 3 hour course utilizing lecture, demonstration, handout rnaterials, and hands-on practice with the appropriate equipment.

Reference Material: 
"The Fifth Vital Sign", Porter, Merlin & Heller, Emergency magazine v.22, n.3
Mosby's Paramedic Textbook, Sanders, pp. 280-281, Mosby Lifeline, 1994
Materials from the manufacturers of this equipment

Testing/Evaluation: Each student will be evaluated in his/her knowledge and use of this device during the hands-on session. A brief written test will also be utilized.  

Purpose: The purpose of this program is to prepare the student to use a portable pulse oximeter in conjunction with other appropriate equipment in providing care for ill and/or injured patients.

Learning Objectives: At the conclusion of this program, the student will be able to:        



  • State the principles of pulse oximetry as they relate to patient assessment and oxygen therapy
  • State the normal values for pulse oximetry
  • Identify conditions which can adversely affect a patient's oxygen saturation
  • Identify conditions which can produce erroneous readings in pulse oximetry
  • Demonstrate on a live human patient the proper use of a pulse oximeter** Note: It is suggested that the instructor add a one-hour review of system anatomy, physiology, and pathophysiolgy of disease and trauma to the respiratory system when presenting this program.  
    1. Introduction (5 min)
      1. To assess the respiratory & circulatory status of a patient, prehospital providers must rely on:
        1. Patient’s description of chief complaint
        2. Patient's overall appearance
        3. Patient's vital signs, including:
          1. pulse rate & strength
          2. respiratory rate, depth, and effort
          3. temperature & skin moisture
        4. Patient's level of consciousness
      2. Within recent years, new technology has produced the portable pulse oximeter
        1. Evaluates oxygenation at the peripheral circulatory beds
        2. Can provide information concerning the level of oxygen actually reaching the tissues
        3. Can provide a means of monitoring the effects of oxygen therapy
      3. These new devices, however, are not without their pitfalls
        1. Certain medical conditions can alter the machine's interpretation, and give false readings
        2. Certain environmental conditions can also produce false readings
      4. When using pulse oximetry, it is important to consider the readings within the overall context of the patient's history and physical exam.
        1. Don't rely on just one number to guide your care. Consider the pulse oximeter reading as you would any other single piece of information. LOOK AT THE WHOLE PATIENT.
      5. The purpose of this class is to not only show you how and why pulse oximeters work, but to show you how to put the results you get into the right perspective, and take the best care of your patient.
    2. Regulations, Guidelines, and Protocols (20 min)
      1. There are currently no state regulations governing the use of pulse oximeters in the field.
      2. State guidelines require appropriate training for ambulance service personnel prior to a pulse oximeter being put in service on an ambulance.
      3. Previously, pulse oximetry was limited to advanced life support (EMT-I and EMT-P) providers.
      4. Current standard of care allows the use of this skill by Basic level providers.
        1. Providers must, however, be properly trained in the use of the equipment and interpretation of results.
        2. All basic personnel must complete this training program or an approved equivalent prior to using pulse oximeters.
    3. Theory and Mechanics of Pulse Oximetry (20 min)
      1. Pulse oximeters use two sensors and a light source to determine the percentage of oxygen saturation in the blood. Simply put, the device uses the color of the blood to determine its oxygen content.
        1. Each sensor looks for a different color of light
        2. Oxygenated blood is a brighter shade of red than un-oxygenated blood.
        3. The device measures the difference between the two to determine the percentage of oxygen saturation.
      2. The probe must be placed in a pulsing vascular bed
        1. Identifies arterial blood.
        2. The device also identifies pulse rate and displays pulse beats in either a "wave form" or via a moving column.
        3. Most devices will not provide a reading unless a pulse is detected.
        4. The mast appropriate location for the probe tip is either the nail bed or the earlobe.
        5. Other sensors are available for use on the bridge of the nose, or using the skin in the anterior axillary area.
      3. Pulse oximeters are generally considered to be accurate within 2 to 3%.
        1. The chief value of readings is identifying whether the patient is improving or deteriorating, based on serial readings, rather than in a single reading.
      4. The resulting numbers are expressed as "percentage of oxygen saturation" (SaO2).
        1. When reporting by radio, this may be expressed as "02 Sat is (#)"
    4. Basic Assessment Using the Pulse Oximeter (15 min)
      1. The basic principles of patient assessment remains the same. The pulse oximeter is an additional assessment, not a substitute for other elements of the assessment.
        1. Primary Assessment
          1. A,B,C's
        2. Resuscitation phase
          1. This is where you will normally obtain baseline vital signs, apply oxygen, etc.
          2. IF APPROPRIATE FOR PATIENT CARE, apply the oximeter and obtain a baseline reading prior to initiating oxygen.
            1. This normally takes only a few seconds, and can be done by one person while the other is hooking up the oxygen mask.
            2. Obtaining a pre-oxygen administration level can be helpful to the physician, since later readings will likely be altered by the oxygen you have given.
          3. Apply oxygen devices as you normally would without the benefit of a pulse oximeter reading.
            1. Patients who exhibit difficulty breathing, or any signs of circulatory difficulty, should receive high-flow oxygen via non-rebreather mask, regardless of oxygen saturation readings.
        3. Secondary Assessment
          1. Whenever you re-take vital signs, note and record the pulse oximeter reading
      2. Interpreting the results
        1. Normal oxygen saturation is considered to range between 97% and 99%.
        2. Readings between 93% and 97% may be normal for some patients
          1. On the other hand, some patients may be very sick with a reading of > 97%!
        3. Readings of 90% or less may indicate that the patient needs ventilatory assistance (i.e. bag-mask ventilation with 100% oxygen) -- check your patient!
        4. By comparing pre- and post-oxygen application readings you should be able to see if your oxygen delivery is resulting in improvement.
    5. Conditions Which Adversely Affect Pulse Oximetry Readings (20 min)
      1. A number of factors can result in inaccurate readings
        1. Carbon Monoxide Poisoning will result in an artificially high Sa02 reading.
          1. remember, the machine is looking at the color of the blood. CO turns arterial blood bright red.
        2. Cigarette smokers will often have altered readings
          1. Since cigarette smoke contains carbon monoxide, they may have artificially high readings
          2. If they have been smoking for a long time, it is not unusual to see an Sa02 of 93-95% as their normal reading
        3. Cold extremities may lead to low readings
          1. due to poor circulation to the extremity
          2. you may be able to warm the hand and fingers by rubbing prior to applying the probe, however this doesn't always work
          3. remember also that a truly hypothermic patient may be able to survive relatively low oxygenation, due to his reduced metabolic state
        4. High-intensity lighting may lead to abnormally high readings
          1. this can be corrected by either turning off the bright light or moving elsewhere
        5. Hypovolemia may lead to artificially high readings
          1. the hemoglobin may be well saturated with oxygen, but there's less of it so the tissues may not be getting as much as they need to survive
          2. this patient is in, or headed for, shock, and should be getting high-flow oxygen anyway
          3. this may also result in so weak a pulse that the machine cannot detect it, and will therefore give no reading
          4. inability of the machine to detect a pulse despite repositioning may be your first indication that the patient is going into
        6. Caution in Cardiac Arrest cases
          1. peripheral pulses may be so weak that the machine cannot detect them
          2. if the machine is detecting a pulse with CPR you're probably doing pretty good CPR!
          3. As arrests continue without return of spontaneous circulation, the peripheral vascular beds tend to shut down, and pulse oximetry readings get more erratic
        7. Anemic patients may produce normal or near-normal readings, but may not be getting enough oxygen at the cellular level (similar to hypovolemic patients)
        8. Pulse oximeters may have difficulty sensing color in dark-skinned patients
          1. often, repositioning the probe will correct this
        9. Fingernail polish may prevent the machine from working
          1. surprisingly, you can often get a good reading through nail polish
          2. if the machine will not produce a reading, use nail polish remover, or switch to an ear probe
          3. you can try turning the probe sideways on the finger, or use the great toe
        10. Some medical conditions, such as Raynauds disease, and some medications may cause peripheral vasoconstriction
          1. be sure to note in patient history and meds section of your report
        11. Excessive patient movement can alter readings
          1. make sure patient remains still when taking readings at the scene. Be alert for shivering or trembling that may alter reading
          2. generally, the motion of a moving ambulance will not substantially alter readings
        12. Failure to clean and maintain the device (particularly the probe) properly may result in false readings  
    6. Techniques for Using the Pulse Oximeter (10 min) This section will be devoted to the operating characteristics of the device used by the agency involved. Materials provided by the manufacturer will be utilized as handouts. This section will, at a minimum, cover the following topics:
      1. Proper appilcation of the finger probe
      2. Activation of the unit
      3. Ensuring that the machine is detecting a pulse
      4. What to do if a pulse is not detected
      5. Proper application of other types of probes available to the provider
      6. Obtaining serial readings
      7. Use of other ancillary features (pulse rate, automatic b/p, printers1 etc.)
      8. Deactivation of the unit  
    7. Practice Session (45 min) In this session, students will practice using the device on instructors and their fellow students. Hopefully, the diversity of each group will provide opportunity for discussion of variations between individuals. The session should continue until all students are comfortable with the operation of the device, and should include all functions of which the machine is capable.  
    8. Maintenance (5 min) This section will rely on manufacturer's information to provide guidance on maintaining the devices, and shall include at a minimum:
      1. Location of battery compartment
      2. Identification of type of battery power used
      3. If rechargeable batteries are used, characteristics and type of battery and recharging recommendations
      4. Cleaning and maintenance of probes
      5. Inspection of the device for loose or broken wires damaged contacts, etc.
      6. Trouble-shooting techniques for common problems, including:
        1. machine will not activate
        2. machine activated, but no reading provided
        3. replacing a faulty sensor probe
        4. other ancillary functions of the machine fail to work
      7. Cleaning, maintenance and proper storage of the device
      8. Documentation of maintenance checks  
    9. Question and Answer Opportunity (10 min)  
    10. Written Examination (30 min) 



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