NO DESAT is an acronym created by Dr. Richard Levitan, a nationally recognized authority on airway management, for Nasal Oxygenation During Efforts at Securing a Tube. This very simple concept will allow you to have more time to intubate while maintaining adequate oxygenation. Although nasal oxygenation is a key component of hypoxia prevention during intubation, there are a variety of techniques that should be used to maximize patient safety.
When we intubate, we want to prevent oxygen desaturation throughout the procedure. This can be achieved by extending the period of time your patient maintains adequate oxygen levels despite not breathing or receiving artificial respiration, such as during Rapid Sequence Intubation. Fortunately, we are learning a great deal about maximizing apneic oxygenation (as this is called) and the techniques to achieve it are very easy to implement. We should all be doing these things routinely.
Pre-oxygenation is critical in extending the amount of time a patient can be apneic and maintain normal oxygen saturation. In the past, this has typically been achieved by using 100% non-rebreather mask, or bag-valve-mask for those that require assisted ventilations. (Note: do not use the BVM instead of the NRB mask for spontaneously breathing patients. It only delivers high flow oxygen during bagging.) For most patients, these techniques will achieve high levels of oxygen saturation and will allow adequate oxygenation for routine intubations.
However, many patients are difficult to oxygenate adequately (severe pulmonary pathology), or have physiology that causes them to desaturate quickly (morbid obesity or severe medical illness such as sepsis), or have an anticipated difficult airway (poor anatomy, c-spine, angioedema). For all of these patients, additional techniques should be employed to maximize the time during which you can perform the intubation before the oxygen level drops.
Pre-oxygenation with CPAP or BIPAP has been found to be very useful for the patient who is difficult to get well-oxygenated prior to the intubation procedure. Another excellent technique is to add nasal cannula oxygen during pre-oxygenation, which fills the nasopharynx with 100% oxygen and provides an additional reservoir of oxygen to draw upon.
This leads us to NO DESAT, which refers specifically to the use of high flow nasal oxygenation during the intubation procedure. It has been shown in multiple studies that this technique significantly extends the time that an apneic patient maintains adequate oxygenation, allowing you more time to safely intubate. The technique is to leave the nasal cannula in place, with high flow oxygen running, while the intubation is performed. The only modification you might need to make in your ED to implement this today is to have 2 oxygen ports available. (There are double port stems that can be purchased if 2 ports are not accessible. The quick solution is to use a tank for the second O2 source.) High flow nasal oxygenation can be irritating, so it’s best to start at 5-6 L/minute, and to turn it up to 15L/min once the patient is sedated or induced.
Dr. Levitan strongly advocates for nasal oxygenation during pre-oxygenation as well as during the intubation procedure. Log in to Medscape to see an interview where he discusses the merits of this strategy.
If you don’t have a Medscape account, you can quickly sign up for a free account using the same link. Alternatively, you can read the interview transcript.
In summary, pre-oxygenation is an important part of the intubation procedure. It enhances patient safety by allowing the operator more time to intubate before hypoxemia ensues. In combination with pre-oxygenation, the use of nasal oxygenation delivered via nasal cannula will maximize the time that a patient can endure apnea without oxygen desaturation. The techniques outlined here do not require special equipment or skills, and we encourage you to use them on a routine basis in your practice.
There are a variety of additional techniques to improve the safety of intubation that we will address in Intubation Tips, Part 2.