By Arthur Hsieh

You will need to know when it is necessary to oxygenate for the EMT exam. EMTs used to give oxygen to everyone, regardless of what the complaint was. Chest pain? Give oxygen. Toe pain? Yep, give that gas too! Medical experts have since discovered that inhaling more oxygen than necessary can be harmful for certain conditions, and it isn’t helpful in situations where it isn’t necessary.

This means that you need to assess the patient for his ability to absorb and use oxygen. You do this using your powers of observation coupled with a pulse oximeter. If the patient appears to be ventilating adequately (having a good tidal volume and rate, without the use of accessory muscles), check for oxygen saturation levels with your oximeter. Ideally, the saturation level should be between 94 and 99 percent.

What does this mean? If the patient is breathing normally, and his oxygen saturation level is greater than 94 percent, you don’t need to administer oxygen. If the saturation level is lower or normal but the patient has mild respiratory difficulty, a nasal canula with oxygen flowing between 2 and 6 liters per minute (LPM) is probably fine.

If the patient is working hard to breathe, a nonrebreather mask at 12–15 LPM may be needed. Carefully monitor saturation readings and the patient’s level of distress. If things don’t improve, you may need to provide manual ventilation.

Oxygen is carried on hemoglobin proteins located within the red blood cells (RBCs). Each hemoglobin can carry up to four molecules of oxygen. As hemoglobin picks up oxygen, the color of the RBC changes from a dusky, dark red to a brighter shade.

A pulse oximeter can detect these shades of red and calculate the percentage of red blood cells that are carrying oxygen in their hemoglobin. Normal amounts are around 94 percent or higher. Once oxygen saturation drops to about 92 percent, the change in subsequent saturation levels can be quick, dropping to 85 percent or even lower within a few minutes.

A 42-year-old male is complaining of abdominal pain and cramping after eating a fried chicken dinner. He is alert, with pink, warm, diaphoretic skin. His vital signs include a pulse rate of 92, a blood pressure of 142/90 mm Hg, and a respiratory rate of 18 breaths per minute. His oxygen saturation level is 96 percent. What should you do next?

  • (A)Administer oxygen at 4 LPM with a nasal cannula.

  • (B)Administer oxygen at 15 LPM with a nonrebreather mask.

  • (C)Perform a secondary assessment.

  • (D)Begin immediate transport.

The correct answer is Choice (C). Based on the patient’s chief complaint, relatively normal vital signs, and lack of evidence of respiratory distress, oxygen, Choices (A) and (B), is not indicated. There is also no indication of an emergent condition that requires immediate transport, Choice (D).