Different devices are used by the respiratory therapist to monitor a patient’s respiratory status and to ensure that the therapy is being delivered as intended.

An oxygen analyzer, is a very important device in our profession, it measures the percentage of oxygen being delivered to a patient receiving supplemental oxygen. The sensor of the oxygen analyzer can be connected to the oxygen delivery system proximal to the patient to measure the inspired oxygen concentration. One very common example in the neonatal area is with the use of an oxyhood, where the oxygen analyzer is used to measure the percentage of oxygen being supplied to the baby. Assuring a precise oxygen percentage is critical with neonates as they are more susceptible to the adverse effects of a, high FiO2, which will lead to oxygen toxicity related complications, such as retinopathy of prematurity, bronchopulmonary dysplasia, and respiratory distress syndrome (RDS. On the other hand, if the neonate does not receive enough oxygen, it may cause brain damage due to hypoxia. That is one example of why having a precise measurement of oxygen is critical in health care. 1-2

Oximetry is a simple, noninvasive and relatively inexpensive patient monitor that gives valuable information about the patient’s oxygenation status. Specifically it measures the oxygen saturation of patients. It has a sensor that is placed on the finger or other sites with good capillary blood flow. It works by using a light source on one side of the sensor that sends infrared and red light through the skin to a light detector on the other side of the sensor. Hemoglobin that is saturated with oxygen absorbs more infrared light whereas hemoglobin that is less saturated with oxygen absorbs more red lights. A microprocessor calculates this difference, which is displayed as oxygen saturation. Common sites for placing the pulse oximeter sensor are the fingertips, earlobes, toes, and occasionally, the forehead. Dark skin and nail polish may interfere with light transmission through the skin, resulting in inaccurate measurement. In addition, low perfusion may give inaccurate readings, which we as health care providers should have in mind when treating hypotensive or hypothermic patients who tend to have low perfusion. Another case where the pulse oximeter may have an inaccurate reading is in a patient with carbon monoxide poisoning, which is commonly seen in fire victims. The reading will be affected since carbon monoxide has a great affinity to bind with hemoglobin. In this case, the device will display a falsely high reading for arterial oxygen saturation even though the patient is hypoxic. Consequently, we should not use pulse oximetry in situations such as smoke inhalation where carbon monoxide levels are high, but draw an arterial blood gas and perform co-oximetry. 1-2-3

Dealing with critically ill patients requires the respiratory therapist to be knowledgeable about different devices that help in managing various conditions. Improving his/her critical thinking skills and knowledge regarding the principles of operation of these devices and correctly interpreting the information generated by the various devices are important in helping the respiratory therapist provide safe and effective care.

Reference:

1-Egan’s Fundamentals of Respiratory Care book

2-Mosby’s Respiratory care Equipment book

3-http://www.rtmagazine.com/