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INFECTION CONTROL
pneumonia by about 35 percent. If you looked more closely at the data, it turned out that the patients who got the silver tube and the patients who didn’t had identical outcomes in terms of the amount of time they spent on the ventilator, the amount of time in the ICU, the amount of time in the hospital and the rate of death. “The answer to the paradox has to do with the subtlety as to how we actually diagnose pneumonia; the problem being that our ways of diagnosing pneumonia are not very good. One of the components of the defi nition for pneumonia used in this trial was that the patient had a positive culture of fluid coming from out of the endotracheal tube. There’s a circularity where the endotracheal tube is coated with silver so it reduces the amount of microbes on the tube. So if part of your diagnostic defi nition is what can you culture from the tube, you should see a decrease. “But that doesn’t necessarily mean you’re decreasing true invasive clinical disease inside the lungs. You might just be measuring the reduction in bacteria that are sitting on the endotracheal tube itself. I believe that’s what happened with the intervention where they found a reduction in bacteria: that they were measuring the reduction in microbes inside the tube, but won’t actually see a decrease in the true lungbased pneumonias. That’s why there’s no difference in the amount of time these patients spent on the ventilator or in the ICU of the hospital, whether they got the special tube or not.” Diagnosing VAP is often difficult, because the relevant patient population is complicated. People on ventilators are generally very sick, with many overlapping serious conditions. There could be changes in the amount of fluid in the body, some of which then spills over into the lungs. These patients are at risk of getting blood clots that travel up to the lungs or of pressure-related damage from the ventilator itself. “If the ventilator gives air to the lungs in an uneven fashion, that part of the lungs might partially collapse,” Klompas says. “All of these things I’m describing can look just like a ventilator-associated pneumonia because they all make your chest X-ray abnormal, and they can all interfere with the amount of secretions coming out of the lungs. They can all give you fever. They can all give you a high white count. “There are all these mimickers, things that look like ventilator-associated pneumonia, but if you were to do a biopsy of these people’s lungs, you would find that it was something else causing the symptoms. All the signs we use to diagnose VAP are non-specific in this way. We look for fever. We look for elevated white blood cell
KLOMPAS ED P48,49,50,52.indd 54
The three hallmarks of VAP treatment:
1
Start early
2
Choose a broad regiment
count. We look for more sputum coming out of the tube, and we look for an abnormal X-ray. And all these findings have many potential causes. “If you took a series of patients who were diagnosed with VAP by their doctors and the patients died and you carried out an autopsy or a biopsy, it would turn out that of the patients suspected of having VAP, maybe about half of them would have the disease, and the rest would have something else. “It’s not only a problem of overcalling cases; we also miss cases. And often, the patients have two processes going on at the same time. If you look at studies comparing one doctor to another in terms of their diagnosis, there’s a lot of disagreement between them. It’s a bit of a tough nut for people to crack.”
Treatment When it comes to treatment, antibiotics are the standard line of attack. Klompas underlines that they need to be started early and they need to be broad spectrum, to cover the possibility that the patient might have a drug-resistant bacteria. He says the third element is to reassess often, because there’s a high probability
3
Reassess often
complications include barotraumas: pressurerelated damage from the ventilator if the pressure settings are too high for the patient to manage; and fluid balance: putting too much fluid into the body and having some of it spill over into the lungs. Deep-venous thrombosis blood clots inside the legs that travel up into the lungs and cause a pulmonary embolism are another potential problem. There could also be drug reactions, or bleeding inside of the lung. Klompas points out that some of these things, such as pressure damage or fluid balance, may be due to the nature of the underlying condition. “You have to give a patient a lot of fluid because you’re trying to protect their blood pressure, and some of it spills over into the lung. But you had no choice, you had to protect the blood pressure. Th at’s what I was alluding to when I said that these are very sick, very fragile patients. You fi x one problem and cause another.” Given that VAP can have such serious outcomes, are we doing enough to reduce its incidence? Klompas believes we’re on the right path. “Five percent of patients now are get-
“The onus on us now with these intervention strategies is to spread them as widely as possible so they become as much a part of the culture of care as we can make them” that you’re either overcalling the presence of a VAP, or missing something underlying: “It’s important to not just make the diagnosis on Monday and forget about it, but to reassess on Tuesday and Wednesday and to change your course of therapy if things aren’t playing out as you would expect. “If the patient is not getting better, you need to consider that something else might be causing the problem. If the patient gets better overnight, it probably wasn’t VAP – so you should stop those antibiotics before they cause some harm of their own.” Other issues to be considered in the broader category of postoperative pulmonary
ting VAP. If you look at studies from 10 and 20 years ago, that number was more in the 15 percent range, so there’s been a dramatic reduction over time. We’ve hit upon some good strategies now to prevent VAP: avoiding intubation, minimizing the duration of intubation and using ventilated management protocols to get the patient off the ventilator as soon as possible. “The onus on us now with these intervention strategies is to spread them as widely as possible so they become as much a part of the culture of care as we can make them. In that way, I’m hoping we can realize even further improvement.”
10/11/2010 16:38