Hypoxia, increased work of breathing outweigh tachypnea, auscultatory findings in diagnosing pneumonia

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Hypoxemia and increased work of breathing are more important to the diagnosis than tachypnea and auscultatory findings.
Hypoxemia and increased work of breathing are more important to the diagnosis than tachypnea and auscultatory findings.

No single clinical observation reliably differentiates pneumonia from other causes of respiratory illness in children, according to a systemic review published in JAMA. However, hypoxemia and increased work of breathing are more important to the diagnosis than tachypnea and auscultatory findings.

Sonal N. Shah, MD, from the Division of Emergency Medicine at Boston Children's Hospital and Harvard Medical School in Boston, and colleagues reviewed the accuracy of symptoms and physical examination findings in the identification of radiographic pneumonia in children. The researchers included 23 prospective cohort studies, including 13,833 children with possible pneumonia. The prevalence of radiographic pneumonia was 19% in North American studies and 37% outside of North America.

The investigators found that no single symptom was strongly associated with pneumonia. However, they note that the presence of chest pain in 2 studies that included adolescents was associated with pneumonia (likelihood ratios [LR], 1.5 to 5.5; sensitivity, 8% to 14%; specificity, 94% to 97%).

Some vital sign abnormalities were not strongly associated with pneumonia diagnosis, such as fever >37.5° C (LR range, 1.7 to 1.8; sensitivity, 80% to 92%; specificity, 47% to 54%) and tachypnea (respiratory rate >40 breaths per minute; LR, 1.5; sensitivity, 79%; specificity, 51%). Auscultatory findings were not associated with a pneumonia diagnosis, and the presence of normal oxygenation decreased the likelihood of pneumonia (LR, 0.47).

However, the results showed that the presence of moderate hypoxemia (oxygen saturation ≤96%; LR, 2.8; sensitivity, 64%; specificity, 77%) and increased work of breathing (positive LR, 2.1) were the signs most associated with pneumonia.

“In settings where chest radiography is not readily available, increased work of breathing and hypoxemia can be used to identify children with pneumonia,” the investigators concluded. “In settings where pneumonia is commonly diagnosed radiographically, these clinical findings can be used to guide judicious use of chest radiography. Future research should evaluate the predictive value of combining clinical features and pulse oximetry among children with suspected pneumonia.”

Reference

Shah S, Bachur RG, Simel DL, Neuman MI. Does this child have pneumonia? The rational clinical examination systematic review. JAMA. 2017;318:462-471. doi:10.1001/jama.2017.9039

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