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In this lesson, we'll go over oxygen therapy and all of its effects, including indications, precautions and contraindications, and adult dosages. And at the end of this lesson, we'll provide you with a Word about respiratory arrest.
Oxygen is an atmospheric gas that increases the saturation of hemoglobin oxygen and when used at therapeutic concentrations, it can aid the oxygenation of certain tissues as long as the patient isn't in shock or has some other complication, like carbon monoxide poisoning. This could affect the distribution or reception of oxygen molecules within the body and its cells.
Oxygen Indications
Now let's take a look at oxygen indications.
The primary indication for the use of oxygen in ACLS is the presence of hypoxemia, which would be representative of an SpO2 of less than 94 percent, severe respiratory distress, as in asthma, and respiratory depression, as in opioid overdose.
When you administer oxygen therapy after the return of spontaneous circulation, otherwise known as ROSC, it's important to deliver sufficient oxygenation to maintain an SpO2 that's greater than, or equal to, 92 percent but less than 98 percent.
Oxygen Precautions and Contraindications
There are few, if any, known precautions and contraindications for oxygen therapy use in the true hypoxic patient. Precautions should be based on new and ongoing research that reveals the vasoconstrictive properties that hyperoxia may produce.
Pro Tip #1: If you begin to hyper oxygenate a normoxic cardiac patient, studies and research indicate that you might cause lower oxygen absorption and distribution to the patient's vital organs that need oxygenation during a coronary crisis.
Adult Dosage of Oxygen
Now let's look at the adult dosage of oxygen.
The appropriate dose of oxygen will be dependent on the patient's needs and unique oxygen requirements.
Oxygen therapy can be delivered via several different methods, and the percent of oxygenation will be regulated by the flow of oxygen per minute as well as the delivery adjunct you use.
When delivering oxygen via nasal cannula is indicated, you should deliver it at a rate between 2 and 6 liters per minute. If a nonrebreather mask is used, that flow rate should be increased to between 12 and 15 liters per minute.
If the patient's respiratory system is distressed or depressed, or for those patients who are completely apneic (not breathing), the delivery of oxygenated ventilations would be via a positive pressure device like a bag valve mask. In this case, the oxygen flow should be set at 15 liters per minute.
Pro Tip #2: It's important, according to current guidelines, to titrate the oxygen therapy to maintain an SpO2 of at least 94 percent but less than 100 percent. Equally important, is to remember that a restricted airway will affect the therapeutic response of oxygenation treatment.
The use of basic or advanced airway adjuncts may be needed to open or maintain a patent airway in order to treat the patient effectively.
Pro Tip #3: It's important to always monitor the signs and symptoms of the patient, along with electronic and technical monitoring systems, so as to properly treat the patient. Rather than simply relying on electronic and technical monitoring systems alone.
In other words, if the SpO2 reads 92 percent but the patient's skin appears normal, they could have an underlying blood disorder like anemia, which can impede the cyanosis due to a lack of hemoglobin and give the inaccurate appearance of adequate oxygenation.
A Word About Respiratory Arrest
In the last two lessons, we took a look at respiratory distress and respiratory failure. In this Word, we'll look at respiratory arrest.
Respiratory arrest is defined as the absence of breathing and is usually caused by an event such as drowning or head injury. For an adult in respiratory arrest, providing a tidal volume of approximately 500 to 600 ml (or 6 to 7ml per kg) should be sufficient. This would be consistent with a tidal volume that produces a visible chest rise in the patient.
Patients with an airway obstruction or poor lung compliance may require high pressures to be properly ventilated (in other words, to make the chest visibly rise). A pressure relief valve on a resuscitation bag-mask device may prevent the delivery of a sufficient tidal volume in these patients.
Which is why it's important to make sure that the bag-mask device allows you to bypass the pressure relief valve and use high pressures, if necessary, to achieve visible chest expansion.
Excessive ventilation is unnecessary and can cause gastric inflation and the resulting complications, like regurgitation and aspiration. More importantly, excessive ventilation can be harmful as it increases intrathoracic pressure, decreases venous return to the heart, and diminishes cardiac output and survival.
As a healthcare provider, you should work to avoid excessive ventilation, as in too many breaths and/or too large a volume of breaths, during respiratory arrest and cardiac arrest.
