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Ventilation is the movement of air in and out of the lungs, while oxygenation is the delivery of oxygen to the blood. Injuries can affect ventilation and oxygenation. The thoracic cavity contains the heart, lungs, and diaphragm. The intercostal muscles and diaphragm contract during inhalation, causing a vacuum. Exhalation is caused by relaxation. A dermatome map shows where specific parts of the spinal cord are attached. Tidal volume is the amount of air moved in a single breath, while minute ventilation is calculated by multiplying tidal volume by breaths per minute. Rapid shallow ventilation is not ideal for gas exchange. Chest injuries can be open or closed, with closed injuries causing significant damage. the chest, preventing the lungs from expanding. You can get that pneumocorax, which can lead the pericardial to a cardiac tamponade. You can get blood in the pericardial sac causing pericardial tamponade. Ventilation is the body's ability to move in and air out of the chest and lung tissue. Intracostal muscles contract from where it digs out. Diaphragm contracts, pulls down. That negative space is my lung is open, my chest is open, air comes in. Oxygenation is the process of delivering oxygen to the blood by diffusing the alveolus across the alveoli, from the alveoli into the cells. So we have ventilation, which is the act of moving in and air out of the lungs. We have oxygenation, which is getting oxygen on the alveoli. And then we have cellular respiration, which is the delivering of the oxygen to the tissues and the removal of the waste products. Injuries can affect ventilation or oxygenation. Remember the thick principle. Unload the red blood cells with oxygen, deliver them to the tissues, offload the oxygen and waste product, carbon dioxide, unloading for excretion. So we call this here the thoracic cavity. This is the mediastinum, middle sternum, Latin mediastinum. It has the heart, the great blood vessels with the vena cava as well as the aorta, as well as the lungs are on the sides of them. And this is the diaphragm. Your diaphragm moves from about the fourth intercostal space down to almost the umbilicus. It moves this much. But it's not like it's all hollow in here. It actually pushes organs out of the way when it contracts. There's a neurovascular bundle that lies underneath the lowest margin of each rib. And that's what feeds the intercostal muscle, removes the waste product, as well as tells it when it needs to contract. There's a pleural covering that surrounds each lung. And remember the pleural lining, you have two layers. You have the parietal and the visceral. The parietal is attached to the inner wall of my chest. The visceral is attached to the lung. The visceral and parietal are held together by a small amount of serious fluid called surfactant. That allows, so when my intercostal muscles contract and pull my rib cage out, it pulls my lung open because the parietal pleura pulls the visceral pleura, which pulls the lung open. So literally, elastically pulls the lung open and sucks air in. And again, this can be a problem because a hole can get in that and air can get in there and break that seal and now we have air filling up what used to be a sealed hole, sealed lining. So if we look at it, we can see it here is the relationship of the lung, of the ribs with the heart and the lungs and of course the ribs. And in between each rib is the intercostal muscle with the neurovascular bundle. Mediastinum again contains the heart, the lungs, the great blood vessels and the diaphragm as well. It separates the thoracic from the abdominal cavity, but that's not its job. It's not meant as a separator. It's a respiratory organ. It's the main organ of respiration. The intercostal muscles and diaphragm contract during inhalation and that causes that vacuum as we breathe in. And that's basically what happens there. The intercostal muscles contract, pull my rib cage out and I breathe in and then everything relaxes and that overpressure causes me to exhale. Now let's say I went out and ran around the parking lot ten times and I was forcefully exhaling because I needed to get rid of that carbon dioxide. Then my internal intercostal muscles will contract and pull my rib cage back in, forcing me to forcefully exhale because I got to get rid of that carbon dioxide. This is what we call a dermatome map. The dermatome map identifies where in the body specific parts of your spinal cord are attached to. What they're saying there is the level of C5, C6. If you have a fracture below C5, like T1, T2 or all the way down, you have some deficits like a C5, C6 fracture, from here down you'll be paralyzed. But you'll still be able to breathe because your pre-neck nerve that runs your diaphragm comes off the spinal cord at C3 through C5. So as long as your fracture is below C5, you're okay. When it's above C5, it could affect ventilation because it could affect the pre-neck nerve. Those are the patients that end up like Christopher Reeve on a ventilator. What's that? Superman. The original Superman. Not the original, actually his father was the original. He was the second Superman. George Reeve was the original Superman. That was the black and white Superman. Tidal volume is the amount of air moved in or out of the lungs in a single breath. It could be as much as three liters of air per breath. But we're only using about how much? Do you remember? About four to five hundred milliliters. Four to five milliliters per kilogram is what you're using. And half of that is used up in the alveoli, in the bronchioles, so you're really only getting two to three hundred milliliters down at the alveoli. You're really only exchanging gases for two to three hundred milliliters because two to three hundred milliliters of that five hundred actually has to be exchanged in that, in the tubes as it were. Minute ventilation is calculated by multiplying tidal volume by the number of breaths per minute. It's usually about four to five hundred milliliters by about twelve breaths per minute or about six liters of air per minute. That's your tidal volume, that's your minute volume. Changes in even number can affect the amount of air moving. So, if I breathe less, I have less air moving. Or if I breathe more shallowly, and that's one of the reasons why if I breathe shallowly, it's like I'm breathing but I'm not getting any chest rise. I'm only moving about two hundred and fifty milliliters of air. It's not getting in the alveoli. It's stuck in the bronchioles. I'm not exchanging gases down in the alveoli. That's why I need chest rise. I need full breaths. So, rapid shallow ventilation is not good ventilation. I'm breathing very fast, I'm moving a lot of air, but it's not getting down to the alveoli because I'm not taking deep breaths. If you're exercising outside and you're short of breath, it's not breathing faster, it's breathing deeper. Breathe deeper and then fast, well, breathe faster but make sure you're breathing deep. You want to breathe faster but breathe deep. Chest injuries, there are two types of chest injuries. There's open and closed. This would be considered a closed injury but you can see the bruising. That's a seatbelt injury. That kid was flying. That must have been a hell of an accident. Look at the broken skin up here from the seatbelt. That's a seatbelt burn. That's a friction burn from a seatbelt. That's bad. Poor kid. So, two types. Closed and open, a closed chest injury. The skin is not broken, it's basically a bruise but it can be, you can have as much underlying damage from a broken, as well as a closed chest injury. It can cause significant cardiac or pulmonary contusion. Alright, we'll stop here. It's already 9.30. I beat you guys up a lot.