Bacteria causes pneumonia, and pneumonia, in turn, has recently generated its own new data and some controversies, attendees learned at yesterday's Critical Care precourse.
Michael S. Niederman, MD, MACP, led off his talk “Pneumonia in the Critically Ill Patient” with recent research about cardiac risks. “We know that as many as 30% of patients with community-acquired pneumonia (CAP) experience major adverse cardiac events in the hospital,” said Dr. Neiderman, who is a professor of clinical medicine at Weill Cornell Medical College in New York.
The elevated risk continues up to 10 years after a bout of pneumonia, and a recent primate study offers an explanation for this phenomenon. “The study here demonstrates incredibly interesting data,” said Dr. Neiderman about a trial published in the Sept. 1, 2017, American Journal of Respiratory and Critical Care Medicine.
It included six primates with pneumonia, three of whom were treated with antibiotics, and researchers found pneumococcal organisms in the myocardium of the sick animals and cardiac scarring after they recovered. “It continued even after antibiotic therapy,” he said.
Those findings help explain data on cardiac arrests among humans, specifically a 2012 study in CHEST finding that only 62% of pneumonia patients who had in-hospital cardiac arrests were in the ICU, rather than the ward, when they occurred. “That was because there was an abrupt cardiac onset in many without warning,” said Dr. Niederman.
Obviously, not all pneumonia patients should be in the ICU—the 2007 severe CAP criteria from the Infectious Diseases Society of America and the American Thoracic Society are still the standard for that decision, he noted—but the data suggest a possible need for greater attention to patients' cardiac risks.
“We probably generally assess severity without thinking about this, and I'm wondering if this means we need to have a higher level of concern about cardiac events and consider monitoring more routinely in patients with community-acquired pneumonia,” said Dr. Niederman.
On the subject of risk stratification, Dr. Niederman mentioned the quick Sequential Organ Failure Assessment (qSOFA) score, which has been a hot-button topic in sepsis care. A study in the Nov. 15, 2017, American Journal of Respiratory and Critical Care Medicine compared pneumonia mortality prediction by several scores, including the qSOFA; Confusion, Respiratory Rate and Blood Pressure (CRB) score; and the Confusion, Urea, Respiratory Rate, Blood Pressure, and Age (CURB-65).
“It turns out that the qSOFA is one of the worst ways to predict mortality in community-acquired pneumonia,” said Dr. Neiderman. “Even if you like the qSOFA for sepsis, it's not a good mortality predictor in CAP.”
In addition to the uncertainty about how to measure severity of illness, experts in the field are in “turmoil” over new research on the prevalence of bacterial versus viral pneumonia, he said. A study published in the New England Journal of Medicine in 2015 was unable to identify a pathogen in the majority of ICU patients with pneumonia. Most surprisingly, among the 45% with an identified pathogen, viruses were more common than bacteria.
“We're not even sure we believe these data, but they've changed the thinking about community-acquired pneumonia,” said Dr. Niederman. “How important are viruses? I don't think we know.”
He did caution that physicians should not stop antibiotics as soon as a pneumonia patient is found to have a virus, because bacteria could also be present and require treatment to cure the pneumonia. “You might not get the bacteria [result] back as quickly as you're going to get your respiratory viral panel back,” he noted.
Dr. Niederman reviewed the guidelines and recommendations for antibiotic treatment of pneumonia and offered a few pearls. One of those was on the particular benefits of macrolides, which he favors as a component of combination therapy for severe CAP. “I would always in the ICU choose my macrolide as my second drug … unless I suspect Legionella,” he said. Macrolides have anti-inflammatory effects not provided by other antibiotic classes, Dr. Niederman noted.
Another hot tip in antibiotic dosing related to the kidneys: While everyone knows that antibiotic doses may need to be lowered for patients with impaired renal function, consider that some patients may have the opposite issue, he advised.
Younger, healthier ICU patients with conditions such as recent trauma or surgery may develop augmented renal clearance. “These patients actually need higher doses of antibiotics,” Dr. Niederman said. A study published in Pharmacotherapy in 2015 offered a scoring system to determine the likelihood of augmented renal clearance, based on patients' age, trauma status, and SOFA score.
Finally, Dr. Niederman discussed ventilator-associated pneumonia (VAP) prevention. He noted that some hospitals' intensive efforts to prevent VAP have resulted in significant declines, but no one has really gotten rid of it. “I think it's very unlikely, even if you do everything right, that you can eliminate VAP altogether,” he said.
This is a concern because of the current government focus on ventilator-associated complications. Before hospitals can be held accountable, and even penalized, for such complications, there needs to be hard evidence that they are preventable, according to Dr. Niederman. “We just don't have the information we need to make this the standard of care,” he said.