This post is part of the PEMBlog community acquired pneumonia series. It focuses on the clinical presentation. Did you know that you can diagnose pneumonia with your brain and your stethoscope? You did? Great.
The big picture is that there is no classic set of signs and symptoms that will help you make the diagnosis of community acquired pneumonia (CAP). Some good generalities to keep in mind include the fact that you should know that viral lung infections are more common in babies and preschoolers. You’ll see atypical bacteria (Mycoplasma spp.) in school age kids – but opposed to the fever/cough combo, these atypical infections also come with more extrapulmonary infections like photophobia, headache and rash. Some children with a recent URI will develop a CAP because of secondary superinfection. This happens with otitis media as well. Vaccines reduce the risk of pneumonia from Haemophilus influenzae type b and Streptococcus pneumoniae, but not completely for all subtypes of each. Overall Streptococcus pneumoniae is the most common bacterial cause. Others include Moraxella catarrhalis and non-tapeable Haemophilus influenzae. Mycoplasma pneumoniae, Chlamydophila pneumoniae, and S. pneumoniae predominate in school age and young adolescents. Staphylococcus aureus (especially Methicillin Resistant Staph Aureus) causes about 5% of community acquired pneumonia (and it also makes some kids very sick during flu epidemics – like necrotizing pneumonia on ECMO sick).
Here are some exam findings that are correlative with pneumonia than others:
- Tachypnea (conversely, not being tachypneic helps exclude pneumonia)
- Increased work of breathing
- Hypoxemia
- Adventitious lung sounds (focal crackles/rales)
Other supportive findings include:
- Fever
- Cough
- Localized decreased breath sounds
- Egophonic or percussive changes (nigh impossible to do in babies)
The absence of tachypnea is the most useful clinical finding for ruling out CAP in children!
In febrile children, the Negative Predictive Value of a non-tachypneic child having CAP is 97.4%. The Positive Predictive Value in a febrile tachypneic child is only about 20%. A lot of this is due to the fact that the respiratory rate can increase 8-10 breaths per minute for each degree about normal (Celsius). In younger children, the WHO specifies normal, non-febrile respiratory rates as:
- 2-12 months: 25-40 breaths per minute – tachypnea >50
- 1-5 years: 20-30 breaths per minute – tachypnea >40
You need other findings in the febrile child to more reliably diagnose pneumonia (retractions, grunting, nasal flaring focal crackles etc,.). Overall, combinations of exam findings are more helpful in making the diagnosis. If you have a kid with fever and two of the above – without a past history of asthma perhaps – then your likelihood of pneumonia is higher.
Per the Infectious Diseases Society of America (IDSA) Guidelines, “pulse oximetry should be performed in all children with pneumonia and suspected hypoxemia. The presence of hypoxemia should guide decisions regarding site of care and further diagnostic testing.” This recommendation is strong and based on moderate-quality evidence. So, don’t forget the pulse ox!
The following table comes straight from the 2011 IDSA and will help you determine severity. In short, sicker kids need X-Rays, labs and more aggressive treatment – which I’ll get to in the other posts in this series.
from the 2011 IDSA Guidelines for community acquired pneumonia
There’re pneumonia without tachypnea? We’ve some infants 1-3 months age with coryza, cought and indrawing but your respiratory rate were 40-50. There’s bibliography by that. This article talk some that but, it is not sure.
Does This Infant Have Pneumonia? Peter Margolis, MD, PhD; Anne Gadomski, MD, MPH. JAMA. 1998;279(4):308-313
Thanks
In an infant as you described I’d call that bronchiolitis clinically. The normal RR are guidelines only of course. We all need to look at the entire clinical picture. Thank you for sharing the article – it’s been awhile since I read that one and I’ll reacquaint myself with it.