"The traditional way of making the diagnosis is with the stethoscope; however, physicians have poor agreement on the diagnosis of pneumonia. A better way to diagnose it is by examining respiratory rate," said Michael S. Radetsky, MD, here at the 11th Annual Infectious Diseases in Children Symposium.
If a child has a high respiratory rate - more than 70 - or has retractions or cyanosis, a diagnosis of pneumonia can be made. "This method is used by the World Health Organization [WHO] in every other part of the world but our own. The WHO, in cases where there are no stethoscopes available, much less doctors, had to find a simple way of defining who had lower respiratory tract illness," said Radetsky, who is from the Lovelace Clinic in Albuquerque, N.M. and clinical professor of pediatrics at the University of New Mexico School of Medicine. "Studies found that respiratory rate alone was extremely useful in determining who did and who did not have lower respiratory tract illness."
In fact, in a recent study, respiratory rate was better than using a stethoscope in defining which patients had lower respiratory tract illness. "The respiratory rate could be counted by a medical assistant or a nurse, so that the answer is there on the encounter form before you even see the patient. I would advocate using the respiratory rate augmented by the use of a stethoscope," he explained.
"A recent study found that you were just as likely to make the diagnosis with the WHO criteria as you were with pulse oximetry. In fact, using the two together was less accurate than just respiratory rate alone. I contend that the pulse oximeter cannot tell you who has radiologic pneumonia," he said.
While the X-ray has been considered the gold standard in diagnosing pneumonia, it is not always accurate. "A recent study found that the treating physician tended to over-read the X-ray, because he or she already had an idea of what would be found. There was poor agreement between the treating physicians and the radiologists who read the same films. Consequently, the chest X-ray is not all that it's made out to be," he said.
According to Radetsky, a chest X-ray is not required to make the diagnosis of pneumonia if you are convinced that a patient has pneumonia based on your clinical examination. "Interestingly, chest X-rays cannot differentiate pneumonias based on cause. They should not be ordered unless you need the results as a tie-breaker. A chest X-ray may be indicated in the sepsis evaluation of very young infants who can have occult pneumonia, because they can be breathing fast just with the fevers or with the discomfort of being ill, and you may not be able to use respiratory rate," he said.
Additionally, white counts and blood cultures are rarely helpful in making the diagnosis of pneumonia. "White counts are not useful in defining the cause of pneumonia, and only 2.9% of blood cultures are ever positive in pneumonia. Therefore, they cannot usually be used to make the diagnosis of pneumonia or to determine the cause," he said. "White counts and differentials are not useful unless you need something as a tie-breaker, such as if the decision to use or not use antibiotics hinges on it. Blood cultures should only be taken from toxic children with pneumonia. Additionally, antigen detection should be avoided."
However, even if a child is well enough to be sent home, he or she still may need an antibiotic, depending on the time of the year, the distance he or she lives from the office and the reliability of the parents. If treatment is warranted, Radetsky recommends an antibiotic like amoxicillin.
"So, in general, for infants and toddlers, I would use either no antibiotic or amoxicillin, which we now know, even for resistant pneumococci, is still the best drug given in a higher amount. For the older child, doxycycline or one of the macrolides is probably reasonable," he said.
For the hospitalized patient, a third-generation cephalosporin can be used. "The worry for these children is untreated bacterial disease," he said.
According to Radetsky, the duration of treatment is "until the child is better and then a little bit longer, which is probably about five to seven days."
For your information:
- Radetsky MS. Pneumonia and the office physician. Presented at the 11th Annual Infectious Diseases in Children Symposium. Nov. 21-22, 1998. New York City.