Neuraxial Ultrasound and Combined Spinal-Epidural (CSE) Anesthesia for Cesarean Delivery

CHAPTER 1

Okay, so I'm going to demonstrate a neuraxial ultrasound. We're doing this ultrasound just to mark the site by which we're going to do a combined spinal epidural for a cesarean delivery. So, we use a curvilinear probe. We choose the standard abdominal setting and so you can see it's already been preset. And then it defaults to 15, so we generally don't have to go as deep as that. We'll start off at 12 and we can adjust accordingly. So what I'm gonna do is just show you our basic procedure. So we start off with parasagittal oblique. Sorry about that. It's icy cold on your back. And so what we're trying to do is, and I'll just turn up the gain a little bit, we're trying to follow the interspaces as we go up. So you can see on the left, that's your sacrum, the long hyperechoic line. I'm gonna follow it down there. And that shows you the sacrum. And then what we're trying to do is we look into the interspaces over there. This is the first interspace. So that's L5-S1. This will be L4-5. This is your ligamentum flavum and your dura. So that's where we're aiming to get the block in. This is your spinal canal, and then this is your vertebral body on the anterior side. And you can see this is a classic saw tooth lamina appearance. So we're gonna start to count up. So there's the L4-5 in the middle of the screen. We're trying to angle it so that we can get to the next interspace. And you can see it coming into that interspace. You can see, if you look at the depth of where we're gonna get loss of resistance, we can measure it in a few seconds, but it's around six and a half, seven centimeters. I'm going to get up to that interspace. So now that we have that interspace nicely in the middle, so that's L3-4, I'm gonna flip the probe now so it's horizontal. And you can see we get straight into the interspace. I'll just show you in a few seconds. I'm gonna decrease the depth because now we know we don't need as much depth. Actually, I'll just go to 10. So this is what's classically known as a bat's ear sign. You can't see it that well but I'll optimize the image in a second. There's your transverse processes on either side. And then this points to more or less where you're gonna get your loss of resistance. And then I'm going to unfreeze and then actually mark it off. Some people call it the equal sign where you've got two lines across there. You can see that equal sign, those two lines. So I'm trying to get the image perfectly in the center. You can see the transverse processes pointing towards the depth. And I'm just going to show you something really quickly over here. Let me just get the optimal image. I'm gonna measure where we're gonna presumably get loss of resistance. Remember I said there's your transverse processes. They point into the equal sign. There's one line there and there's one line there. This is the vertebral body. There's the spinal canal. And so by measuring there, we're going to get 6.25, so just over six centimeters. I was pushing quite hard. You want to release the pressure when you actually make that measurement. And so that's bats ear sign, equal sign, and that's a perfect space. I'm gonna go back and just finish the examination. So there's the bat's ear again coming out there. I'm trying to get it perfectly in the middle of the screen. I've marked off this side and I've marked off that side. We're gonna do it. I'm gonna go one interspace higher just to see if it's a bad interspace. And now on the spinous process, you can see that hyperechoic line. Sorry, let me just... That's a spinous process. And the utility behind the spinous process is it's telling you midline. So I'm just going to mark that off. I'm gonna come back into that interspace, L3-4. And I think it's overall the best interspace we have. So I've marked it off here and then we're gonna go directly inside there and that should work perfectly. In terms of the depth, just to go back to the measurement of the depth, if I were to freeze it there, hold on, let me... Again, we'll do a measurement. There's your equal sign, transverse process pointing in, 6.35. So you'll put the needle in at about five and a half centimeters and do the last centimeter feeling for traditional loss of resistance. And that's the ultrasound. I'm gonna mark it off at L3-4 as our interspace. I'm now going to feel the spinous, the iliac crest and feel across there. The iliac crest is actually a little low. We tend to overestimate and go a space or two high if we don't use ultrasound. So this is the end of the preprocedure ultrasound and we're gonna mark off, clean off everything, and we're going to do a combined spinal epidural next.

CHAPTER 2

I'm gonna clean your back off with a cold solution. So we're demonstrating now a combined spinal epidural for this procedure. We've preprocedurally marked the interspace. We found a good interspace at L3-4, which we predict will get loss of resistance at about six and a half centimeters. We use chlorhexidine with a tracer to clean the back off so that it will allow it to dry. And now we're going to be getting ready. We clean our hands prior to any block with a gel solution. So while this is drying, we get a chance to put the gloves on. So this is our kit over here. We have a premade kit. We actually use the ultrasound, these epidural kits. And all we do is we add a spinal needle or a Gertie Marx needle. It's a 26-gauge needle that allows it to extend past the Tuohy needle. So Dr. Blake will actually demonstrate how far it extends past. If you want to take the Tuohy needle out and then put the Gertie Marx through that. So it extends about a centimeter and a half, so 14 millimeters beyond. So that will be able to pierce the dura. And then obviously the Tuohy needle is extended there. So we'll walk you through it. As I mentioned, we've already marked which is the optimal interspace. This is our kit ready. We've marked our local anesthetic there. And then we differentiate the needle, the syringe with the solution with a marking so we know that it contains the local anesthetic. We use a soft, flexible catheter, and that's the epidural catheter that's been unraveled. All right, so a plastic drape goes on your back. So because we've marked with ultrasound, we trust the ultrasound over palpation. So we're gonna use the landmarks that we've indicated. Lean forward just a little bit and then try to, yep, flash out your lower back there, okay? All right, first you're gonna feel a pinch and burn of numbing medicine. One, two, three. So we're very generous with the local and we like to put local so that we get a nice dermal bleb of local so we can move around the interspace as the procedure's happening. Because we ultrasounded and we know the depth, we're going to be quite aggressive with sticking the needle in. We know that there's no loss of resistance for a while. So that's what we're going to be doing. So we comfortably can put the epidural in a good five centimeters. Now the patient moved a little bit between ultrasounding and repositioning. So sometimes, the vertical angle is always accurate, but sometimes the horizontal markings become a little less accurate. So we advance the needle continuously looking for loss of resistance. So the right hand is feeling for loss of resistance as we carefully advance the needle forward. We like a continuous technique. All right, a little off so I'm just gonna do a redirection here. Okay, so again, we trust the vertical marks. So it may mean that we need to just adjust it slightly cephalad or quadad, which is what we're gonna do now, so... So pressure is normal. If you feel any sharp sensations, we can give you more local anesthetic. You're doing really, really well. Little bit of extra pressure. If you feel it sharp, we can give you more local. Just speak up. Does this feel like the center of your back or off to one side versus the other? Do you feel that in the middle of your back or off to one side? One side. Okay, which side do you feel it on? Right side. Right side, that's very helpful. I'm just going to make a slight adjustment here. You doing okay? Yeah. Okay, all right. We're just making a slight adjustment. This feel like more the center of your back? Yeah. Okay, great. Okay, so we've now got loss of resistance there. You saw a very distinct change. And if we count the centimeters, it's one, two, three. So we got in at seven centimeters. This is the Gertie Marx needle. You might feel a little zing. You can see it extends further in. You can see CSF is coming out. We wait for CSF to get all the way to the edge. We use a Luer lock mechanism so we can really tightly apply the syringe. You can see that we're always in contact with the patient's back. So we have the left hand holding the spinal and the Tuohy needle together to make sure it doesn't move. We aspirate it initially and then we only aspirate at the end because we want the needle to do the least moving possible. Remember with the CSE needle, you have a needle within a needle, so it does tend to move more than a single shot spinal. So now we're aspirating back. And we're done. So that's the spinal part. And we're now gonna be threading the epidural catheter. So we're putting the epidural tubing in. You may feel a little tickle as this goes in. That's completely normal. All right. The needle is going to come out of your back in just one second. I'm going to just overthread just a little bit more. We usually leave six centimeters in the epidural space. So we got loss at seven. So we will leave a total of 13. Needle's coming out of your back here, okay? How are your legs feeling? Warm. Great. So that's the combined spinal epidural technique. And now we're going to be taping it in. We like to tape it in a lateral position because there's often movement of the soft tissue. And if we tape it on the skin, then the movement is to pull the catheter out. So we're going to stop it at 13. So that's 15 with the three marks. So we've got two more to go, that's 14 and 13. Clean off the back here. We aspirate to make sure that there's no heme in that. We use a 1-cc syringe. You can see fairly convincingly there's no heme. We'll cap it off. And then we will put on the label later just to save time because we want the block to wear off. We're going to ask her to fall to her side. Yeah, so if you could just lean down to your side and then we will tape this catheter in. There's no needle left in your back. It's just the soft tubing that remains. So just fall to your side. There we go, we've got you. We've got you here. You're doing great, perfect. Okay, just very still here. Still doing okay? So what you'll notice with the catheter is that it's sucked in about two centimeters. So if we had taped, it would have been pulled out by two centimeters. So we're gonna just put an additional one over there. And then at that point we are finished with the procedure. And because we're doing this under surgical condition, she'll be lying on her back during the surgery. We don't need to see it. So we don't have a little window for the epidural. And now we'll tape the last bit and we're basically done with the procedure. All right, and go all the way on your back. You did great. I'm going to label this. So what we generally do for labeling is because this alligator clamp has a tendency to come off, we try and do a little omentum within the catheter. So you can see we do it over there. So not only are we labeling, but we're able to do it so that when there's a pull on the device, it's not pulling from there, it pulls from there. So that's a little trick. You can use other tape, but we generally do it this way.