Case number two. Here he is. Okay. And this is Winston. He is a four year old male, neutered French bulldog, unfortunately, a dog that we're seeing more and more commonly in our clinics over here in the US. He is up to date on his vaccines and he has been previously healthy. He was out playing at the park and he acutely collapsed. Here are his physical exam findings, and you'll note that he is hyperthermic. He's tachycardic and he's tachypnic. His mucous membranes with cyanotic, and he has a marked increase respiratory rate and effort. But he also has marked inspiratory stertor and stridor. So he's got a lot of airway noise as he is trying to breathe. His pulse quality, though, is strong and synchronous. 

Okay. So in his case, we did just do a venous blood gas and here are those results. So I'm going to give you a second to look at these. All right, now I'm just move those over to the to the right side of the screen so that we can evaluate them. All right. Question one. Is our pH normal? The answer is no. And so if the answer is no, what is happening to our pH? Our pH is decreased, which means that we have and acidemia or an accumulation of hydrogen. Is the primary disturbance metabolic or respiratory? So remember, we would expect to see an increase in our PCO2 or a significant decrease in our bicarbonate. So our PCO2 is increased, 56 is greater than 46. And our bicarbonate is normal. So that tells us that our primary disturbance is going to be respiratory. So we can now say that this animal has a respiratory acidosis. Is there compensation? So what would we expect? We would expect that our bicarbonate would decrease, I'm sorry. I'll say that again, our bicarbonate would increase. So our bicarbonate moves in the same direction as our PCO2. Our bicarbonate is kind of like our base. So we would expect that our bicarbonate would increase above 24. And similarly, we might expect that our base excess would increase, so it would become more positive in that situation. So do we see a increase in our bicarbonate or an increase in up base access? And the answer is no. But remember that if you're talking about metabolic compensation, that takes 4 to 5 days to happen. And if you go, think back to how this dog presented the dog presented after acutely collapsing at the park. So we probably wouldn't expect to see a change in our bicarbonate yet because it's just a too short a period to see that change in our metabolic system. So we're not seeing any metabolic compensation. So we can say that Winston has a respiratory acidosis without metabolic compensation. 

So let's talk a little, a little bit more about respiratory acidosis. So what causes us to retain carbon dioxide? So a decrease in our ventilation causes a decrease in our carbon dioxide excretion. Now, this is a very important fact to remember, and that is that carbon dioxide is much more diffusable across our aveolar barrier than oxygen is. So carbon dioxide is about 20 times more diffusable or it diffuses 20 times faster than oxygen across the alveolar barrier. And so that means that with primary lung disease, such as pneumonia, often we see hypocapnia because our hypoxemia triggers us to breathe more, so we have an increased respiratory rate and effort. And that means that our CO2 decreases because that barrier has to be very severely affected in order for it to affect diffusion of carbon dioxide because it's so diffuseable. Okay? So often with primary lung disease, we'll see a respiratory alkalosis. So don't let that fool you. Okay? So common causes of respiratory acidosis would be an upper airway obstruction. So you can't ventilate if you can't get air past your upper airway. So an upper airway obstruction is very common. Inadequate ventilation so meaning that you're not able to move your chest normally. So a classic case of this would be a patient under anesthesia who maybe is on the little too much inhalant and is not ventilating adequately. Or if you have severe central nervous system disease, that is depressing your respiratory center. The other thing would be if you had significant pleural space disease, because, again, you're not able to ventilate because your fluid or air or whatever it might be is taking up space in your pleural cavity, which means that your lung can't expand properly. So just to go back with a respiratory acidosis, decreased ventilation causes, decreased excretion of carbon dioxide. 

Okay. And as we already mentioned, the degree of metabolic compensation, if we are looking at respiratory acidosis, can provide information on how long that disease has been present for because it takes to 4 to 5 days. So in Winston's case, there is no evidence of compensation. And so that's consistent with an acute airway obstruction or brachy, so in his case specifically and unfortunately, we see many, many dogs like this brachycephalic obstructive airway syndrome. So the tissues in the back of his throat are so abnormal that he basically can't ventilate. And so the way that we're going to fix this acid base problem is to probably sedate him some, maybe give him some steroids. But in some cases, the obstruction may be so severe that we actually have to intubate these patients and breathe for them until that airway inflammation subsides.