Fluctuations in relative humidity provided to extremely low-birthweight infants (R1).

Background: In extremely low-birthweight infants, the addition of relative humidity (RH) improves thermal stability, fluid and electrolyte balance. However, during routine care this microenvironment is frequently disturbed. The objective of this study was to determine the frequency, magnitude and direction of fluctuations in RH provided to extremely low-birthweight infants.

Methods: All infants in our study had ambient temperature and RH continuously recorded for 48 h using a datalogger device (RH32S-C2). A clinically acceptable range for RH was defined as the set point ± 10%. A secondary analysis was performed to compare outcomes between infants that spent > 50% of the time out-of-range (OOR) or inside the range (IR). A P-value < 0.05 was significant.

Results: A total of 20 infants were included. Important fluctuations were detected by the device with infants spending 40% and 14% of the time above and below the range, respectively. However, the RH set point did not differ from the mean levels measured over 48 h by the RH32S-C2 or the incubator. Infants in the OOR group spent significantly more time at values higher than the planned range when compared to IR infants.

Conclusion: Although significant fluctuations in RH above the desired range were detected in more than half of the infants, the average values were similar to the set points. Nevertheless, knowledge of these dynamic changes may help to optimize individualized care.