Update Course Rewind: Cryoanalgesia in Pectus Cases 2024

Global Cast MD along with Cincinnati Children's Hospital sharing knowledge to improve child health around the globe. Hello Pediatric Surgery family. I'm Lizzy Lee from Cincinnati Children's Hospital Medical Center. In this video series, we'll be recapping the sessions and sharing the key highlights from our 12th annual update course in pediatric surgery, which was held in August 2024. This year, we introduced a new approach to classify practice changing ideas at our update course. Presentations now fall into three categories: green circles for established practices, blue squares for promising newer practices, and black diamonds for early adopter practices only. Today we are talking about new uses for cryoanalgesia in pectus with pediatric surgeon Dr. John Defuri. This topic falls into the blue category as a newer approach. First of all, what is cryoanalgesia? It is a minimally invasive procedure to repair pectus excavatum or alleviate pain during surgery on the chest wall. It temporarily blocks nerve conduction along peripheral nerve pathways and relieves pain by freezing the affected nerve. I'm going to go through our technique at the clinic. We use a double lumen tube in all patients. The double lumen endotracheal tube is used to deflate the lung on the side where cryoablation is being performed. The surgeon makes bilateral transverse incisions in the axilla and inserts a thoracoscope to guide the cryoprobe positioning against each nerve. The freeze point is in the posterior axillary line, 4 cm from the vertebral column. With the original cryoprobe, it's a 2-minute freeze cycle. We go from T3 to T8, although most of the literature is just to T7. After cryo, we do intercostal nerve blocks with subplural injection. This is the left side of the chest and the landmark to make note of is the subclavian artery going over the top of the first rib. This is cryoablation on the third rib with a 2-minute freeze cycle, and then we work down from the third to seventh rib. After we do that, I do a subplural injection with quarter percent marcaine with epinephrin. This works immediately as opposed to the 8 to 10 hour delay with the cryo nerve block. It takes only 15 seconds per interspace. You can see the exposure that we get from the double lumen endotracheal tube, which is exceptional. It's very quick and easy to do and it and you know that you're getting it right, right on the nerve. Since 50% of the update course audience has never used cryoanalgesia, what is the main barrier? About 40% of the update course responders answered that cost is the main reason they don't use cryoanalgesia. Others mentioned that the equipment just isn't available. A lot of people hesitate because of the time involved, so I'm going to talk just very briefly about that for people who are already using cryo. There is a new probe available that cuts down the time significantly. Doing T3 to 28 bilaterally saves almost 30 minutes. The tip now gets down to temperature about 20 seconds faster. The freeze cycle is 90 seconds instead of 2 minutes. It's 15 seconds less to thaw back to the temperature. There's also improvement on shaft insulation so that it can actually touch the lung since it only reaches room temperature. That's particularly important for people who are not using a double lumen tube where they're crossing the mediastinum and have the lung as an issue. The shaft is also stiffer, so it's easier to place. Here's a picture of the old probe on top and the new and improved probe on the bottom. There's different insulation on the shaft and the temperatures are different. I just want to highlight one paper in Chicago where they did a one-minute freeze cycle instead of a two-minute freeze cycle and they had nerve blocks that were just as effective. This was a limited study because they did not measure pain scores or compare the one minute freeze cycle directly to two-minute freeze cycles. With the new probe, it's only a 90-second freeze and there's actually another new probe that is 10 mm in size that is a 60-second freeze that gets down quicker. That's coming out uh on October 1st. There is a bit of debate on whether or not to use a double lumen endotracheal tube. There is a risk of pneumothorax from the lung tearing after inadvertent adhesion to the cryoprobe. The double lumen endotracheal tube helps minimize this risk by deflating the lung and maximizing working space so that the cryoprobe does not touch the lung. I use it in all cases. The exposure of the intercostal nerves is exceptional and it ensures that you're applying it posterior enough so you get the lateral cutaneous branch and I'm going to show you a diagram. A major advantage of the double lumen tube over the single lumen tube is that it helps prevent the nerve block from being done too far anteriorly, which will make the nerve block ineffective. I've gotten multiple calls from other surgeons that say, sometimes my blocks don't work and invariably, it's a surgeon using a single lumen tube doing the block too far anteriorly because they can't get posterior to that anterior axillary line. Here's the anatomy of the lateral cutaneous branch that we are targeting. We're really trying to make sure that we cover that lateral cutaneous branch. Dr. Song Kim did a cadaver study at UCSF showing that 18% of the lateral cutaneous branch nerves are posterior to the mid axillary line. If you don't get posterior enough, that's when you get blocks that are ineffective. So a double lumen tube greatly facilitates that. However, some surgeons have success with using a single lumen tube doing a mediastinal dissection, going across from the right to the left side. Let's see how many people in the audience use a double lumen tube versus a single lumen tube. So, half and half. So Dr. Kim showed in the study that there is a large collateral branch of the intercostal nerve that runs along the top of the nerve, separate from the main intercostal branch on the bottom of the nerve. In a small group of patients, he cryoablated the main intercostal nerve at the bottom of the rib and the collateral branch at the top of the rib below it. This is what that looks like. This is the standard location for freezing the nerve. As you move down toward T7 and T8, the interspace will widen enough. Anecdotally, Dr. Defuri has done this technique in 20 patients. The peak pain scores have dropped from about 5:00 to about 3:00. It hasn't affected our length of stay because 98% of our patients go home the next day anyway. In the UCSF study, when they did two freeze points per interspace on 22 patients, the length of stay decreased from 2 days to 1 day. Most notably, nine out of the 22 patients reported pain scores of zero. Again, this is a new thing, but it's very easy to do. The probe takes half the amount of time and now I'm doing double the number of blocks. In summary, cryoanalgesia is gaining traction in pediatric pectus surgery. It controls pain and decreases hospital length stay with few short-term complications. The main obstacles to using cryoanalgesia are the cost and equipment availability. Recent advancements with new cryoprobes reduce freezing time and make placement easier, shortening the procedure time. Compared to single lumen tubes, double lumen tubes enhance precision, especially for targeting lateral cutaneous nerves. Global Cast MD along with Cincinnati Children's Hospital sharing knowledge to improve child health around the globe.