November 2021

In this VETgirl online veterinary continuing education blog, Amy Newfield, CVT, VTS (ECC) reviews oxygen delivery methods in veterinary medicine. How do you supply oxygen to your veterinary patients?

Oxygen delivery methods in veterinary medicine

Amy Newfield, MS, CVT, VTS (ECC)

Administering oxygen effectively is the staple for patients experiencing oxygen deficiency. In human patients it’s easier to deliver oxygen when a patient is experiencing respiratory distress. We know the medical professional is trying to help us with nasal prongs, nasal lines or oxygen masks. Our veterinary patients often don’t understand we are trying to help them. As a result many fight the method we have chosen to deliver oxygen. When choosing a method to deliver oxygen it’s important to choose one that is effective, but also the patient doesn’t resist.

HOW TO ADMINISTER
Animals should be allowed to assume any position that provides them the most relief. Sedation should be considered in patients that are very stressed. Sedating a patient will calm them and decrease any hyperventilation that may have been occurring because of stress.

Oxygen Hoods
Oxygen hoods made from Elizabethan collars tend to be well tolerated in dogs, but not as much in cats. It is made by covering 75% of the ventral aspect of an Elizabethan collar with plastic wrap. The Elizabethan collar should be 1 size larger than would normally be used for the patient. The oxygen tubing is placed along the inside of the collar and taped in place ventrally. FiO2 levels can get up to 60% oxygen very quickly and in many cases 80% using 1 L/10 kg body weight of oxygen. The oxygen hood is only for short-term use because humidity will build quickly and may cause a panting patient to overheat. Glad Press-N-Seal is a product that can be used to quickly cover the e-collar to turn it into an oxygen hood.

Oxygen Cages
Oxygen cages are popular because they are convenient. Turn them on and put the patient in them and walk away. There are three main problems with commercial oxygen cages.

1) The length of time it takes for an oxygen cage to get up to 40% FiO2 is long and varies on size.

2) You also cannot work with your patient if they are in a cage. Every time the door is opened, the oxygen escapes and plummets the FiO2 to room air very quickly so the patient becomes dyspnic again. The patient experiences an oxygen rich environment-room air-oxygen rich environment very quickly.

3) Cost. The cost of the cage itself is expensive as well as the cost of the oxygen. The oxygen cost can be up to 10 times greater than with other methods.

That said, I find with cats in particular placing them quickly in an oxygen cage is one of the best method to delivering oxygen to them quickly and effectively. Cats do not like to be handled in general so placing in a cage is the least stressful method for them.

Flow-By Oxygen
There are no studies showing how efficacious this method is. I do not like for one simple reason: Pets don’t like to have air blow on their noses. Using face masks will certainly make it more effective, but it they are poorly tolerated. It is important to remember to remove the diaphragm on the bottom of the oxygen face mask. Having a tight seal around the pet’s face will not allow for appropriate ventilation. The efficacy of this technique is still debated since it is unknown how much of the oxygen the animal actually intakes. The oxygen tubing must be less than an inch away from the animal’s nose in order for it to be effective. If it is more than an inch away much of the oxygen is likely dissipated into the room air surrounding the patient. Animals sometimes will tolerate this technique is an owner holds the animal and the oxygen line.

Nasal Cannula
This is a technique that is well tolerated by most dogs and cats. This consists of a short human nasal cannula that has two sections of tubing coming from a small nose piece. There are three sizes: infant (cat and small dog), pediatric (medium sized dog) and adult (large dog > 25 Kg). By using a few drops of proparacaine or lidocaine in each nostril, most patients will allow the tips of the cannula to be placed into the nostrils. The tubing is brought to the side of the nose and secured with staples or suture. The remaining tubing is brought behind a patient’s head and secured so it doesn’t flop in front of the face. Ideally a humidifier should be attached to this so that the nasal passages are kept as moist as possible. Oxygen rates depend on the patient. In general a rate of oxygen is started at 50-100 ml/kg up to a maximum rate of 5-6 Liters/minute.

Dog with bilateral nasal oxygen cannulas

Nasal Catheters
This is one of the most effective ways to provide oxygen to the patient, but often not well tolerated. Patients can have two nasal lines placed if the first is not improving the patient’s oxygenation status. Oxygen being administered into nasal lines should always be humidified to avoid nasal passages drying out. With patients with head trauma, severe thrombocytopenia and nasal disease, nasal lines should not be used. Sneezing will elevate intracranial pressure.

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