Hello, I'm Joseph Spinelli, Chief of Neurosurgery at Walter Reed National Military Medical Center, and also at Uniformed Services University of Health Sciences. This is part of the panel on VTE prophylaxis and neurosurgery. My part in particular is going to be focusing in somewhat on adult degenerative spine surgery as a subset of that. I have no disclosures to report. So, as we know, in general, some of the general statistics here, DVT-PE has a significant impact of patient safety, not just in spine surgery or neurosurgery but across the board, looking at hundreds of thousands of patients affected annually with approximately 100,000 deaths directly or indirectly attributable to DVT-PE. Overall impact is about $1.5 billion annually, comprised of extra medications, extra prolonged hospital stay, and patient follow up. We're looking at about a $10,000 increase cost per person for patients undergoing major surgery, which has been complicated by VTE for the reasons I previously listed. Particularly in adult degenerative spine surgery, we don't really have a great idea of the true VTE incidence. The rates in the literature, really ranging over the past 20 to 30 years, are all over the place, down from a minuscule 0.2% all the way up to 1 in 3. The symptomatic rates, of course, being lower at about 1 to 2% here, so a better range on the symptomatic rates. Across neurosurgery, when we look at where are the highest rates in VTE occurrence, of course, we have spinal deformity surgery, as are some of the other higher rates of complication in general. There are some of the highest risk categories here, the prolonged perioperative immobilization, in conjunction with anesthetic time of greater than eight hours, that's often not seen in other subspecialties. Also, in adult degenerative spine surgery, we're dealing with a higher risk population with ages often greater than 60, BMI greater than 30, medical comorbidities, as mentioned, the longer operative times, and also the poor immobilization after surgery. Some of these larger surgeries, patients are immobilized for several days. So we get to VTE prophylaxis, how do we attack the problem of the VTE PE that was discussed previously. Part of the problem is a very difficult risk to benefit profile. As mentioned, the high morbidity mortality of VTE, particularly with PE, but there's also high morbidity with risks of initiating too aggressive a prophylactic regimen. We have the the offsided risk of post chemoprophylaxis hematoma. In spine surgery and extensive spine surgery, we have exposed spinal cord with cervical and thoracic surgeries, and or nerve roots with the lumbar surgeries, where hematoma can have somewhat devastating neurologic effects. In this subset of patients, we see this post chemoprophylaxis hematoma as high as about 3% of cases, sorry, 3.5% cases, and 50% of the patients that do have deficit with the post chemoprophylaxis hematoma up to 50% may be left with a permanent neurologic deficit. In trying to look at guidelines and to see if there are any societies or any any guidelines by which to guide practice, the current set admittedly are vague and based off of only fair or insufficient evidence. There's a lot of grade B recommendations at best, and more commonly just work group consensus statements. If we go through a few of those now we've got the North American Spine Society, which issued some guidelines back in 2009. The highlights of that being recommendations for pneumatic compressive devices in the lower extremities that are just suggested with elective spinal surgery. They kind of depart from the focus of adult degenerative kind of large deformity spinal surgery and focusing in on just all all spinal surgery in general. So they're suggesting the compressive devices in elective spinal surgery. Chemoprophylaxis may not be warranted in the more simple elective posterior approach spine surgeries, the posterior cervical laminectomies, the one or two level lumbar fusions, minimally invasive or not, that's that category. They go on to say that low molecular weight heparin may be used postoperatively following circumferential front back surgeries, or in subsets of high risk patients. That's considered carefully because of the risk stated earlier, case by case basis. And even within that there's really no literature to support an ideal timing of initiation of the low molecular weight heparin, even in these high risk patients. Also the Neurocritical Care Society in 2016. They stated that in standard elective spine surgery. Really recommending just a ambulation with mechanical prophylaxis being the graduated compression stockings or the intermittent pneumatic compression devices. Those alone, or combined with low molecular weight heparin and in more complicated spine surgery, using the pneumatic compression with heparin or Lovenox. They specifically recommend against the routine use of IVC filter. That's routine use, we'll get into that a little bit. Multiple IVC filters can be used temporarily. Sorry there. Only in patients with the demonstrated PE and DVT or with DVT at risk for PE who cannot be anticoagulated. Those being too close to the perioperative or postoperative window. The European guidelines for perioperative ET prophylaxis discussed a lot of specialties, but with the subset of neurosurgery. They stated spinal surgery with no additional risk factors, early mobilization only. Not even really touching on the mechanical prophylaxis of the stockings or the pneumatic compression. And in spine surgery patients with additional risk factors, that's where they state mechanical prophylaxis with the pneumatic compression. And to add low molecular weight heparin postoperatively when the risk of bleeding is presumed to be decreased. So again, getting into this lack of guidance on any kind of ideal timing, but just weighing that risk benefit window of a postoperative chemoprophylaxis hematoma. Often we'll talk about IBC filters in complex deformity spine surgery. There is some literature primarily based on case series going back about 20 years, particularly a couple papers out of Northwestern. But there is somewhat limited limited evidence that stated really just a couple of case series. These suggest that the rates of PE can be reduced from 13% to 3.7% in these groups of high risk patients for which IBC filters were used perioperatively. And as mentioned, the Neurocritical Care Society recommends against the routine use of IBC filters, stating that complication rates can be upwards of 2 to 5%. However, as mentioned, these may be considered in high risk populations. And what are these high risk populations? Well, going through some of those case studies and case series on the use of IBC filters, they were used in patients that were considered high risk to be, as you see here, history of DVT-PE, concurrent malignancy, hypercoagulability, prolonged perioperative immobilization. Which is typically considered a greater than eight hours of the anesthetic time or a greater than five segment levels of fixation. And again, those circumferential approaches, particularly lumbar where there is a heliocable manipulation with exposure of the anterior lumbar spine. So, as we like to say, when we don't have very good guidance or good literature to guide the recommendations, well, what can we do? Typically, we would need to study it more, but that's likely to be a problem here, as we're unlikely to have a prospective randomized controlled trial. There are, quite frankly, just too many variables to address. For instance, we'd need to compare patient demographics and risk factors against the relative complexity of the surgery, and those complexities can be broken down into the type of approach. Is it the number of levels? Is it the circumferential approach? Is it heliocable manipulation? Are these ambulatory cases or are these inpatient cases where there's typically going to be a longer period of immobilization? What type of VTE prophylaxis is being used? Is it all these various patients with compression stockings only or a combination with pneumatic compression devices with or without low molecular weight heparin or unfractionated heparin? When were those prophylaxes, whether mechanical or pharmacologic, when were they initiated? How long were they initiated for, etc.? So really, there are so many variables to address that we're unlikely to have a randomized controlled trial that is able to analyze all of those subsets. And of course, this has really led to, as stated, more consensus recommendations, but also individual institutions developing and publishing their institutional guidelines. The classic, well, here's what we do, and this is how it's been working, so maybe you want to try this. That's led to some things such as the development of VTE prophylaxis, this risk-benefit score, and a few other modalities. So to wrap up here, it's a complex issue, high morbidity and mortality caused by not only the problem, but also by some of the fixes and initiation of chemoprophylaxis. So the best offer is to take the guidelines, take them for what a lot of them are worth, and develop a sensible, practical approach that works in your practice and for your patients. That's all I have. Thank you very much.

VTE prophylaxis

neurosurgery

DVT-PE

risk factors

complications