Volumetric capnography assesses lung function in preterm infants

Volumetric capnography can feasibly be used to assess lung function or the degree of lung disease in spontaneously breathing preterm infants, a recent study has found.

The study included 143 very preterm infants (mean gestational age 28.5 weeks) who underwent volumetric capnography at 36 weeks postmenstrual age (PMA). Twenty-nine infants were deemed to have bronchopulmonary dysplasia (BPD), defined according to the 2001 National Heart, Lung, and Blood Institute Workshop Report; meanwhile, 13 had severe BPD.

Compared with the 101 no-BPD controls, infants with severe BPD showed significantly steeper mean normalized phase III capnographic slopes (SnIII; 76/L vs 261/L; p<0.001). The same was true when comparing severe vs mild BPD infants (76/L vs 31/L; p<0.001); the difference between mild and no BPD was not significant.

Similarly, capnographic index (KPIv) was significantly elevated in severe BPD infants (93 vs 22; p<0.001).

Multivariable regression confirmed that the log SnIII (β, 1.048, 95 percent confidence interval [CI], 0.769-1.326; p<0.001) and KPIv (β, 1.148, 95 percent CI, 0.806–1.490; p<0.05) were significantly correlated with severe BPD. A similar but inverse effect was discovered for the normalized phase II capnographic slope (SnII; β, –0.159, 95 percent CI, –0.303 to –0.014; p<0.001).

Receiver operating characteristic curve found that the areas under the curve for SnII, SnIII, and KPIv for discriminating between infants with vs without severe BPD were 0.34, 0.94, and 0.92, respectively.

“The technique is independent of components of care and may serve as a simple, objective, and inexpensive alternative to more complex lung function tests for determining the degree of lung injury in preterm infants. Further research is required to assess lung function tracking and the long-term prognostic value of this test,” the researchers said.