Hi, you learned in the last section about how the lungs and airways work together to get oxygen to the rest of the body. You also have learned about assessing how well a patient is protecting their airway and breathing. In addition, we discussed about all of the tools at your disposal to assist with the patient's airway and breathing. Now, that we have a good grasp on what normal should look like. Let's take a look at what happens when these mechanisms go wrong. The ability to accurately and comfortably assess how well a patient is breathing is what we will refer to as their respiratory status, and their airway is a critical part to a reliable patient assessment. Airway pathology can be divided in many ways. First, we think of the upper airways and the lower airways. Issues anywhere along the airway or even external to the airway can lead to difficulty breathing. We will start in the upper airway, so let's take a big deep breath and dive in. Let's talk about airway obstruction. As you have learned, the airway starts with the Oropharynx or Nasopharynx and continues as the trachea and into the Bronchi and then divide into the smaller airways. All of these areas can become obstructed or blocked by a number of things, and that can easily in pair how oxygen can get to the Alveoli. Remember, the Alveoli are the only place that oxygen can cross into the bloodstream, so getting it there is very important. We often think of things like steak, peanuts, small beads, and other objects that can cause obstruction. They can get lodged in the larger airways or even smaller airways resulting in a complete or partial blockage of the airway. A patient with an airway obstruction may be making the classic choking sign. But an obstruction may also be more subtle. For example, you may hear stridor or see a patient drooling and leaning forward. Oftentimes, patients that have an airway obstruction look very distressed or ill. Keep this in mind, if it's obvious that a patient cannot breathe. There are other mechanisms that can obstruct an airway. These include, infection or swelling. Epiglottis is an infection that affects the Epiglottis, these patients are often very ill, drooling and have fevers. Interestingly, Epiglottis used to be a disease of children. However, routine vaccinations have made this much less common in children and now it's more common in adults but still remains a very rare illness. Other important infections to consider are in the deeper spaces of the neck and Oropharynx, Ludwig's Angina as an example of an infection in the soft tissues of the floor of the mouth. This can cause a significant amount of swelling that will ultimately elevate the tongue and can obstruct the airway. So, as far as airway emergencies, just keep in the back of your mind that there should be a nice smooth track for the air to flow from the environment to the Alveoli. Anywhere along the way, objects, swelling, infections, and other mechanical processes can obstruct this path, thus leading to an airway emergency. Now, let's take a breather and switch to the lower airways.