Ventilation and Perfusion (Nursing)

00:01 Hi, welcome to our respiratory video series.

00:03 Now, in this one, we're gonna look at V/Q ratio.

00:07 I promise, this is really more important than it sounds right now.

00:11 There's a little bit of math but it's gonna make perfect sense.

00:15 Okay, so, let's start out with a question.

00:17 What are the two most important things needed by the lungs to provide adequate oxygen to the cells? So, what are the two things? I promise you know this.

00:27 Just take a deep breath and think about it.

00:38 Okay, the lungs need two things but it's really all about the alveoli, okay? Because the lungs need oxygenated air to be delivered to the alveoli and they need a good blood supply to the alveoli to take that oxygen and deliver it to the cells.

00:56 So, this is an important part of this video series.

00:59 You need to keep in mind that in order for my cells to get enough oxygen, I need oxygenated air to the alveoli and blood passed the alveoli to take that oxygen to my cells.

01:13 So, those are the two things that you need. Oh, is she gonna say it one more time? Yes, she is. You need oxygenated air to the alveoli.

01:23 You need good blood supply passed the alveoli to get it to your cells.

01:29 See, that's the whole basis of looking at V/Q.

01:33 In healthy lungs, your alveoli, remember, bringing the upper airway, you get to the trachea, the big bronchi, down to the little bronchioles, then, you've got the alveoli at the end.

01:44 That grapelike crest, those structures, that's where the CO2/O2 exchange happens but it couldn't' happen unless you have the capillaries which surround those alveoli and that's where the exchange happens, over those really sensitive membranes.

02:01 Now, we're just talking about how fast the alveoli receive air and how fast that blood supply is going past them.

02:10 So, we know, just take us at our word, that the alveoli receive air at approximately four liters a minute.

02:18 That's an important number, so, underline the four.

02:22 Now, the capillaries supply blood, so, when everything's healthy, blood is going by there at a rate of five liters a minute.

02:30 So, we know that you -- the blood is going faster than the air is coming but that's a normal balance for lungs. So, alveoli receive air at four. The capillaries supply blood at five.

02:45 That's gonna matter cuz we're gonna see those two numbers an awful lot in the coming parts.

02:50 So, alveoli deals with ventilation, capillaries deal with perfusion. That makes sense.

02:56 Alveoli is air, capillaries is blood, that's perfusion, good deal, and perfusion means we want really good oxygenated blood.