Understanding oxygen and CO₂ exchange is the key to everything from cardiac care to acid–base balance. In this episode of Think Like a Nurse, Brooke Wallace breaks down anatomy, assessment, and critical clinical cues every nurse must know to master the respiratory system.
Episode Title: Respiratory System Made Simple: What Every Nurse Must Know
Created by: Brooke Wallace – ICU Nurse, Organ Transplant Coordinator, Clinical Instructor, and Author
Website: ThinkLikeANurse.org
Core respiratory anatomy nurses need to know cold
Why the right main bronchus is the “danger zone”
The 4 key steps of respiration: ventilation, external respiration, transport, internal respiration
Boil’s Law and how pressure changes drive breathing
The role of surfactant and what happens in ARDS
The oxyhemoglobin dissociation curve simplified — Right Release vs. Left Lock
Age-related respiratory changes and clinical implications
How to identify wheezes, rhonchi, and crackles — and the right nursing response
Oxygen therapy, suctioning, positioning, and prevention strategies for better outcomes
Right main bronchus = wider, shorter, straighter → aspiration risk.
Boil’s Law: volume ↑ → pressure ↓ → air flows in.
Negative intrapleural pressure keeps lungs inflated — pneumothorax breaks it.
Right Release, Left Lock: low pH (acidosis) helps oxygen release; high pH (alkalosis) makes it harder.
Wheezes = bronchodilators, Rhonchi = suction or cough, Crackles = fluid or alveoli collapse.
Older adults: less reserve → rapid decompensation under stress.
Assess before you touch: rate, rhythm, effort, color.
Cyanosis = late sign of hypoxia.
Always correlate SpO₂ with patient appearance and ABG values.
Use positioning as your first non-pharmacologic intervention.
Patient education — smoking cessation, vaccines, proper inhaler use — prevents readmissions.
A post-operative patient is vomiting and at risk for aspiration. Which nursing action best protects the airway?
A) Place in supine position
B) Trendelenburg position
C) Left side-lying position
D) Encourage deep breathing
✅ Answer: C – The left side-lying position helps prevent aspiration into the right lung, which is wider and straighter.
00:00 Intro
02:10 Blueprint of the respiratory system
08:15 Boil’s Law and ventilation
14:30 The 4 steps of respiration
20:00 Oxyhemoglobin curve
26:00 Aging and respiratory reserve
32:00 Lung sound interpretation
40:00 Nursing interventions and education
48:00 NCLEX Challenge
Welcome to Think Like a Nurse. This is the show where we really try to bridge that gap between what you learn in the books and what happens at the bedside. We take those complex nursing topics and uh really break them down to make them easier for you to grasp and use. And I just want to give a quick shout out to the creator of Think Like a Nurse, Brooke Wallace. She's got an amazing background, 20 years as an ICU nurse, organ transplant coordinator, clinical instructor, and she's a published author, too.
That's right. And today, we are digging into something absolutely fundamental. Yeah, the respiratory system. I honestly understanding how we get oxygen in and CO2 out. It's the bedrock. You can't really manage fluids, cardiac stuff, acid base balance, none of it without getting this down first. It really is the master key, isn't it? So, uh, non-negotiable knowledge for sure. And hey, if you're looking for more resources after this conversation, always remember to check out think like a nurse.org. But yeah, let's jump into the system. Maybe start with the um the blueprint. The anatomy nurses need to know cold.
Okay, perfect starting point. Big picture first. The main job is super elegant, right? Supply oxygen, get rid of carbon dioxide, it all happens through gas exchange. And if you really understand where that gas exchange happens, well, that informs basically all your assessments, right? So, it starts uh upstairs with the air conditioning, basically the upper tract, like the nose, it's not just a filter. Those twisty passages, the conce. Yeah, they're amazing. They massively increase the surface area to warm and humidify the air, right before it goes deeper. Exactly. And you've got that siliated mucosa doing the filtering, trapping all the gunk. Okay. And then that air moves into the fernx, the throat area. Yep. The common passageway for air and food. Then comes the larynx, the voice box. And this is where some serious protection kicks in. You mean the epiglotus. That's the superstar protector. Yeah. That little flap seals off the windpipe when you swallow if it messes up. That's aspiration. Big problem.
Huge problem. Yeah. And that leads us right into the lower tract, the trachea, the windpipe with those C-shaped cartilage. R is keeping it open, right? But here's a really critical point, uh, a clinical warning sign for every nurse really. The trachea splits, it bifurcates into the two main bronchi, one for each lung. What's the danger zone here? It's the anatomy itself, the right main bronchus. It's wider, it's shorter, and it goes almost straight down compared to the left one. Okay. Wider, shorter, straighter on the right. That sounds like a pneummonic waiting to happen.
Huh, maybe. But the bedside implication is serious. So, what does that mean? Practically for patient care, think path of least resistance, any foreign object, food, vomit, even sometimes an ET if it's advanced too far. It's much more likely to end up in the right lung. Statistically, yes, by far. So, when you're positioning a patient, especially one who's maybe vomiting or just posttop, you remember that. That's often why we might position them slightly on their left side using gravity to help protect that straighter right airway. Makes sense?
Absolutely. That's a fantastic practical tip rooted right in the anatomy. Okay, so Moving deeper past the broni we get to the lungs themselves. Left side has two loes, right has three. Correct. All wrapped in that slippery plura for protection. And then way down at the microscopic level, the alvioli, the tiny air sacks. This is where the magic happens, right? Gas exchange central. Precisely. Their walls are incredibly thin, just one cell thick sometimes, which allows for super rapid diffusion of gases into the capillaries right next to them. And they make something critical called Surfactant.
Ah, surfactant. Why is that so important for us to remember? What does it do? It's basically lung detergent. It reduces the surface tension of the fluid lining those tiny sacks. So, without it, they'd collapse. Yep. Especially when you exhale. The surface tension would just pull them shut, making it incredibly hard to breathe. Think about conditions like ARDS, acute respiratory distress syndrome, right? A severe lung injury. Yeah. Surfactant function often gets compromised there. Takes a lot more pressure to keep those alvoli open.
And they're a little Cleanup crews down there, too. Macrofuge. Yep. The alvola macrofage. You're the last line of defense, gobbling up any dust or microbes that manage to get all the way down. Okay. So, we've built the structure. We know where things happen. Now, how does the process work? How do we actually breathe? You mentioned physics earlier. Boil's law. Exactly. Breathing or pulmonary ventilation. It's pure mechanics driven by Boil's law. Remember, volume and pressure are inversely related. Change one, the other changes in the opposite direction. So to breathe in inspiration, we need to make the chest cavity bigger.
You got it. That's the active part. The diaphragm contracts, flattens out. The external intercostal muscles pull the ribs up and out, increasing the volume inside the chest, which drops the pressure inside the lungs below the pressure of the air outside your body. And air just rushes in naturally down that pressure gradient. Dingo. But here's a key clinical point. This only works if you maintain negative intraplural pressure. That's slight vacuum in the space between the lung and the chest wall.
Uh so if air gets into that space like with a pumothorax the lung collapses that negative pressure is lost and the lung can't inflate properly. That's why things like chest tubes are so vital. They restore that negative pressure. Okay. So that's ventilation step one but you mentioned four processes earlier, right? Four key steps for respiration overall.
And that transport piece, step three, how oxygen hitches a ride on hemoglobin. That links directly to acidbased balance, doesn't it? Absolutely critical link. We have to talk about the oxyhemoglobin dissociation curve. It sounds complex, but it's fundamental. Okay, break it down for us. So, hemoglobin carries oxygen. And this curve basically shows how easily hemoglobin grabs onto oxygen in the lungs where there's lots of it and how easily it lets go of oxygen in the tissues where it's needed.
And things can shift that curve, right? Make it easier or harder for hemoglobin to let go. Exactly. And the big shifters are things like pH, temperature, and CO2 levels. This is where it ties into acid base. So if a patient is acidotic, maybe their pH is low because of high CO2. What happens to oxygen delivery? Good question. Acidosis shifts the curve to the right. Think right release. Right release. Okay. Yeah. It means hemoglobin lets go of oxygen more easily which is actually helpful. The tissues that are acidic and working hard need that oxygen more. So the body facilitates its release there.
And the opposite alkyossis high pH shifts the curve left. Hemoglobin holds on to oxygen tighter. Left lock. Left lock. Got it. So just looking at the pulse ox2 doesn't tell the whole story. Not at all. Saturation tells you how much hemoglobin is carrying oxygen but not how readily It's giving it up. You need the AG, the arterial blood gas, the pH, the P2, oxygen level, and arterial blood, and the PAC O2 carbon dioxide level to see the whole metabolic picture, which connects to how breathing is controlled. It's mostly chemical, right? In the brain stem, the medulla and ponds, primarily chemical.
Yeah. The medulla sets the basic rhythm around 12, 15 breaths a minute typically. The pawns help smooth it out. And it's a common mistake to think our bodies primarily react to low oxygen, isn't it? It is. While very low oxygen does eventually stimulate breathing, Our main trigger minute to minute is actually the level of carbon dioxide in the blood and the resulting change in pH. So if CO2 climbs, the blood becomes more acidic. Chemo receptors pick this up instantly and signal the brain stem, breathe faster, breathe deeper. The goal is to blow off that extra CO2 and bring the pH back to normal, preventing or compensating for respiratory acidosis. Precisely. It's a very sensitive feedback loop.
Now, let's connect this physiology to age. We know So things change as we get older. How does that impact breathing? Yeah, efficiency definitely decreases. The lungs lose elasticity, kind of like an old rubber band. The chest wall gets stiffer. Respiratory muscles might weaken. So they can't take as deep a breath or exhale as forcefully.
Exactly. They tend to have an increased residual volume. That's the air left in the lungs even after you breathe out fully. What's the clinical takeaway there? Less reserve. Much less respiratory reserve. An older adult might look fine at rest. Normal SPO2 maybe, but put any stress on their system, an infection, surgery, even just getting out of bed. Sometimes they can't ramp up their breathing effectively to meet the demand, right? They don't have that extra capacity. They can decompensate or crash much more quickly than a younger person. That's why careful monitoring during activity or illness is so crucial for older adults.
That reduced reserve is a perfect segue into our next section, the nurse's toolkit. How do we actually assess this system at the bedside, spot trouble early, and what do we do about it? Okay. assessment. It starts the second you see the patient, even before you touch them. Vital signs, obviously rate, depth, rhythm of breathing, but also what's the effort like? Red flags you're looking for immediately. Dysmia, are they reporting shortness of breath? Is it visible? Look for accessory muscle. Use neck neck muscles, draining, nasal flaring, especially in kids. Are they tripoding?
Leaning forward on their arms to try and open up the chest. Exactly. That's a classic sign of significant respiratory distress. Orthopia, too. Can they only breathe comfortably sitting up? Then we listen. Oscultation. Such a core nursing skill. What are we listening for? And how do those sounds guide what we do next? You're listening for normal sounds first, like vicular sounds, those soft rustly noises over most of the lung fields. But the key is identifying the abnormal or adventitious sounds.
like wheezes, right? Wheezes, those high-pitched musical or whistling sounds, usually louder on expiration. What does that tell you immediately? Airways are tight. Restricted bronco spasm maybe. Yep. So your first thought should be bronco dilators. Yeah. Medications to open those airways up. Okay. What about rounchy? Rounchies are different. They're lower pitched kind of rough snoring or rattling sounds. Often just thick secretions, mucus in the larger airways. and sometimes they clear up if the patient coughs. Often they do. Yeah. So if you hear runchy, your plan shifts. Yeah. Think hydration, encouraging coughing, maybe suctioning and they can't clear it themselves. You need to move that mucus out. Makes sense. Then the third common one Crackles, also called rails sometimes. Correct. Crackles are more discreet popping sounds like velcro being pulled apart or hair rolled between your fingers near your ear. They usually don't clear with coughing.
And what do crackles typically indicate? They usually point to issues in the smaller airways or the alvoli themselves. Could be fluid pulmonary edema, heart failure maybe. Yeah. Or it could be collapsed alvoli atasis popping open when they inhale. So the intervention is different again. Not suctioning for crackles generally not. No. If it's fluid, you're thinking diuretics, fluid restriction, if it's adalctasis, maybe deep breathing exercises, incentive sperometry, sometimes positive pressure ventilation like CPAP to help pop those alvioli open. That differentiation is so key. Wheezes, tight airways, bronco dilators, runchy junk in big pipes cleared out, crackles, flutter, collapsed, small stuff, diuretics, or recruitment.
That's a great way to summarize it. And beyond listening, don't forget basic inspection. Looking at chest rise and fall, is it symmetrical? Yes. and color. Skin color. We rely heavily on pulse occimmetry. That's B2 reading should be above 95% ideally. Ideally, but remember cyanosis, that bluish tinge to the skin or mucous membranes, that's a late sign. If you see that oxygenation has been seriously compromised for a while. And for the definitive picture, the AG arterial blood gas, that's our gold standard diagnostic snapshot. Gives you the pH, the P2, the HO2, tells you about oxygenation, ventilation, and acid base status all at once.
Okay. For students maybe trying to organize all the potential problems, can we briefly categorize common respiratory disorders? Sure. We often think in broad categories. You have obstructive disorders where air gets trapped. There's things like COPD which include the chronic bronchitis and emphyma and asthma. Okay. Obstructive trouble getting air out generally. Yes. Then you have infectious problems. Pneumonia is a huge one. Tuberculosis, TB, and then other serious things nurses need to be aware of definitely pulmonary embolism PE. a clot in the lungs and ARDS which we mentioned that severe lung injury leading to respiratory failure. Lots of overlap of course but those categories can help organize your thinking.
So once we've assessed and have an idea of the problem the nurse's role becomes very active with interventions. What are some immediate non-drug things we do? Positioning is massive. Someone's short of breath get them sitting up fowlers or high fowlers position. Gravity helps pull the abdominal organs down away from the diaphragm. Letting the lungs expand more easily maximizes that thoracic volume.
Exactly. Then there's oxygen therapy itself. Making sure they have the right delivery system from a simple nasal canula to more complex masks and that it's working correctly and maintaining a clear airway effective suctioning technique is crucial if they can't clear secretions themselves. And of course monitoring the effects and side effects of medications like bronco dilators or steroids. Constantly assessing response. Yes. Finally, empowering the patient. Education is huge here. Oh, it's Maybe the most important long-term intervention prevention first like smoking sessation.
Absolutely. Hammering on smoking sessation. Yeah. Encouraging vaccinations, the flu shot, the pneumonia vaccine, especially for vulnerable populations. Simple hand hygiene to prevent spreading infections and teaching patients what to watch for. Yes. Teaching them the signs of worsening respiratory distress, increased shortness of breath, chest pain, changes in sputum, and making sure they know how to use their own equipment properly, like their inhalers. Correct technique makes a huge difference.
This has been a really fantastic run through. We've covered that key anatomy, remembering that danger zone and the right bronus. Wider, shorter, straighter. Got it. The mechanics, Boil's law, driving ventilation, the importance of negative pressure and the oxyhemoglobin curve linking oxygen delivery to pH. And then there's essential assessment skills. Really listening to what those lung sounds are telling you, considering age, and knowing the basic interventions and connecting it all back to your nursing practice. This foundation is exactly what lets you identify and address those core nursing diagnoses. Impaired gas exchange, ineffective airway clearance, ineffective breathing patterns. Understanding this system, really understanding it is how you start to truly think like a nurse.
Couldn't agree more. Okay, before we wrap up, here's a final thought, a clinical challenge for you listening. We talked about age differences. A sick infant breathes really fast, right? Maybe up to 30 times a minute or even more. While an older adult, as we said, has much less respiratory reserve. So, think about assessing these two patients. What's maybe the single most important different thing you'd prioritize when assessing that sick infant with their rapid rate versus the crucial thing you'd monitor closely in the older adult when they just do something simple like getting out of bed into a chair. Consider their different capacities for effort.
Oh, that's a great practical application question. Really makes you think about tailoring your assessment. Thank you so much for walking us through all of this today. Really vital information. And thank you for tuning in. We hope you'll join us again. For more conversations designed to help you connect nursing theory to real world practice, for more study aids, tools, and resources to help sharpen your clinical judgment, please make sure to visit think like a nurse.org. We'll talk to you next time.