I'm Naomi O'Grady, I'm from the National Institutes of Health Clinical Center, and I will be presenting the SCCM and IDSA guidelines for evaluating new fever in adult patients in the ICU. I have no conflicts to disclose, and I want to give a shout out to all of the panelists and co-authors that were on this guideline. This guideline appeared in print in November in the Critical Care Medicine Journal. It's available on the website at both the SCCM and the IDSA websites, and there's a lengthy supplement that's also available that goes along with the guideline detailing the methodology and the recommendations. So the objectives for this talk are to, number one, become familiar with the 2023 updated guidelines for evaluating new fever in the ICU. Understand that in contrast to the 2008 guideline, of which this is an update, this guideline uses GRADE methodology, and that the panel produced 12 recommendations and nine best practice statements. Understand that not all febrile episodes require an aggressive fever investigation. For example, there are some things that are quite obvious in clinical practice. A post-operative patient on post-op day one with a new fever doesn't require necessarily an aggressive fever workup, and also know that a good history in physical will determine the type of testing that is needed. These are some of the topics that I'm going to touch on briefly during this talk. All of these were covered in great detail in the guideline. It includes measurement of temperature, the treatment of fever, imaging studies, blood cultures, urine cultures, testing for viruses, and biomarkers of inflammation. So I'll start with a case presentation. A 29-year-old male diagnosed with sickle cell disease presented to the NIH Clinical Center with chest pain and shortness of breath. He has a history of acute chest syndrome, for which he's been admitted multiple times. On admission, his blood pressure is 100 over 65, heart rate is 110, respiratory rate 36, temperature 38.3, oxygen saturation 88% on four liters nasal cannula, and he's transferred to the ICU for analgesia, bronchodilators, empiric antibiotics, and transfusion. On arrival to the ICU, his temperature is now 39.0, and here is his rather unremarkable chest X-ray. So how should we approach the workup for this fever? In many ICUs, in many hospitals, a knee-jerk approach would be approached, would be started with a set of orders, an order set that would encompass lots of diagnostic testing. So one of the purposes of this guideline was to guide a little more narrowly the diagnostic testing that goes into fever management. So for those of you who are not familiar with GRADE methodology, what is it? It's the formulation of PICO questions. PICO questions stands for Population, Intervention, Comparison, and Outcome. So we looked for studies that had specific outcome measures when we evaluated the literature. We had a professional librarian develop search strategies for each and every question. We searched the recent literature, i.e., 10 years old or less, and then we used updated meta-analyses or pooled randomized controlled trials, if appropriate. The methodologists assessed the quality of evidence, and the panel voted on the strength of each recommendation. So what is the definition of fever? For the purposes of this guideline, our panel used 38.3 degrees Celsius, but it was important for us to emphasize the emphasis of individualized care, in that young people will have a more robust fever, while elderly patients may have a more muted response. So we encourage people to try to avoid fixed cutoffs and to follow trends in patient's temperature. It's much more meaningful to look at the change than the absolute number. When fever is detected, most people jump to infection as the root cause, but there are other causes which this guideline touches on. So I'll talk a little bit about measuring temperature, because we do get a lot of questions about that, and the one issue that the panel tried to address is, what is the most accurate way of measuring temperature? And I'm sure these pictures are familiar to everybody during COVID days, when we all wanted to take people's temperatures from far, far away, and make sure we didn't come anywhere near them, but yet get an accurate temperature measurement, usually outside in the freezing cold weather. So for those of you who saw the humor in that, as I did, I think we can all chuckle in retrospect. So what is the most accurate way to measure temperature? Well, the panel issued a recommendation that said central temperature monitoring methods, including thermistors for pulmonary artery catheters, bladder catheters, and esophageal balloon thermistors, are preferred when these devices are in place, and accurate temperature measurements are critical to diagnosis and management. For patients without these devices in place, we suggest using oral or rectal temperatures over other temperature methods that are much less reliable, such as axillary, tympanic membrane temperatures, noninvasive, temporal artery thermometers, or chemical dot thermometers. This was a weak recommendation with very low quality evidence, unfortunately. But what we will say is that we did take the level of evidence from this particular systematic review and meta-analysis and updated it with a few other studies. We are not recommending the routine use of central thermometers. So what this PICO question highlighted was whether or not precise temperature assessments improve clinical outcomes. If the most accurate evaluation of body temperature won't change clinical practice, the use of an invasive method to assess it could be inappropriate. And the analogy I would like to draw your attention to is how frequently we use noninvasive blood pressure monitoring. We don't always use invasive blood pressure monitoring, and noninvasive blood pressure monitoring is very, very helpful. In the same way, temperature assessment, depending on the patient population, doesn't always have to be absolutely precise, and following trends might be much more important. We next address the question of treatment of fever. Should we treat fever with ibuprofen or acetaminophen? The data shows no benefit, at least not to the patient. There may be some benefit in treating fever for the patient, for the people around the bedside. But should fever be routinely treated with antipyretic medications? There might be some special circumstances if the fever causes hemodynamic instability. For example, putting additional cardiac workload burden, which may trigger an infarction in certain patient populations. Fever that might trigger seizures in patients should also probably be treated. We used this meta-analysis and updated it, but the bottom line from this was that antipyretic therapy effectively reduced temperature in non-neurocritically ill patients, but does not reduce 28-day mortality, hospital mortality, or shock reversal. Of course, as we embark on a fever workup, suspicion for infection should always be at the top of the list. And we did emphasize the importance of empiric treatment with antibiotics, noting that time is of the essence. We want to rule out other causes of fever, but be aggressive about starting and stopping antibiotics while that workup is being undertaken. So what imaging studies should be used in the ICU in terms of working up fever? Again, a good history and physical will guide which imaging studies one would use, but a chest radiograph is a good starting point, as many patients who are in the ICU are at risk for pneumonia, pleural effusions, abscess. These can usually be done at the bedside, and that's an important consideration when we thought about imaging studies for patients' evaluation. The need to transport patients is something that we would like to avoid, and sometimes having the ability to do it at the bedside overrides some of the other considerations. Other imaging studies are based on history and physical. extremely helpful, particularly in postoperative patients, patients who have abdominal signs and symptoms, and sometimes even if expertise exists in the ICU staff, lung ultrasound is quite helpful. Chest CT scans for chest, abdomen, and pelvis are used based on pretest probability of finding something, and PET scans are not routinely recommended but could be helpful in rare circumstances. The next topic we addressed was blood cultures. And the question was, should blood cultures be obtained from central venous catheters? The answer was, in general, yes, even though there is a strong bias against drawing blood cultures from catheters because they are more prone to contamination. But collecting only peripherally minimizes contamination, but it doesn't allow you to sort out where the fever is actually coming from. So using a differential time to positivity, in other words, drawing blood cultures peripherally and from the catheter, if the blood culture from the catheter turns positive more than two hours ahead of the peripheral culture, it gives you a very good, strong indication that perhaps the catheter is the source of the infection. It's notable that yield is dependent on the volume of blood collected. If volume is too small, you may get a false negative result. And the number of lumens sampled improves the yield as well. Please sample all lumens if possible, although your microbiology lab may not appreciate that. Collect blood cultures before antibiotics are initiated. This is important, but do not delay the initiation of antibiotics in lieu of blood cultures. Should urine cultures be sent? This is always somewhat of a conundrum in the ICU. Urine cultures are complicated to collect properly, and they are complicated to interpret. But pyuria and symptoms are important in patients who can communicate. In patients who cannot communicate, pyuria could be important, but your level of suspicion for the urinary tract being the source of fever is more important. So patients who have histories of stones, et cetera, obstruction of the urinary collecting system, those are patients who would be at a higher suspicion for having the urine be the source of fever. In patients with Foley catheters in place, we suggested placing a new catheter before collecting samples. That's a critically important issue in terms of getting a clean catch or a clean sample and having the best information available to assess. We addressed the issue of viral panels in patients in the ICU. Viral pathogen testing should be a part of fever evaluation in patients with suspected pneumonia or respiratory symptoms. There's no question about that. Any patient with respiratory symptoms should have a viral panel sent. Viruses may be single or they may be co-pathogens. Now it's important to detect these because some viruses have therapies available, so it's very important to identify. It's also notable, though, that viruses are transmitted in the healthcare setting. New fevers in hospitalized patients could be viral-related. So we didn't really, we did not specifically suggest that only patients with pneumonia or respiratory symptoms get a viral panel sent. Patients in the ICU could have easily picked up a virus from the healthcare environment, the healthcare workers, visitors, guests, et cetera. So it's important to do viral pathogen testing as part of a fever evaluation. The last topic we addressed was biomarkers of inflammation. We developed at least five, maybe six PICO questions on this topic and settled on a recommendation that says in patients with low probability of infection, it's reasonable to check either a procalcitonin or a C-reactive protein. An elevated biomarker should trigger an aggressive search in this patient population, but biomarkers that are normal should trigger a reduction in empiric antibiotics more quickly than if otherwise. Biomarkers alone are not sufficient to rule out infection. In patients who have a high probability of infection, we do not recommend checking biomarkers because it really isn't going to impact the clinical care. So I know that that was fast, but to conclude, I would say there are important advances that have been made, but there are plenty of knowledge gaps that remain. And there is a need for rapid advancement in all areas of testing. Also measurement of temperature and the need for reliable, non-invasive core measurement devices, better use for diagnostic imaging, especially at the bedside, and better randomized control trials comparing one methodology to another. Appropriate use of rapid molecular testing and the use of biomarkers round up the need for advancement in all areas. So I thank you for your attention. I know that was fast, but I'd be happy to take questions at the end of this session. Thank you very, very much. Dr. Pastores, if you can come up to the podium.

fever evaluation

ICU guidelines

antipyretics

biomarkers

diagnostic imaging