Ceasing or gradually reducing incubator humidity after 7 days for extremely preterm infants: a randomised clinical trial.

The purpose of this study is to compare the effects of two different ways of stopping incubator humidification on episodes of hypothermia, hyperthermia, hyponatraemia, hypernatraemia, or skin injury. The design is a single site, two-armed, parallel, randomised, clinical trial conducted between April 2019 and March 2022. The setting was a quaternary referral and teaching hospital in Queensland, Australia. There were 140 extremely preterm infants, born < 28 weeks gestational age (GA). Intervention groups were (1) cease humidity: incubator humidification turned from 80% to off at 00.01am on day 8 of life (n = 70); or (2) gradually reduce humidity: incubator humidification reduced by 5% at 00:01 of each day from day 8 until ceased on day 14 (n = 70). The primary outcome was episodes of temperature instability: defined as either hypothermia < 36.5 °C or hyperthermia > 37.5 °C. Secondary outcomes included episodes of hyponatraemia: hypernatraemia or skin injury. One hundred forty infants were enrolled, 70 in each group. No statistically significant differences for any outcomes. Hyperthermia: 77% (n = 54) in the cease group and 73% (n = 51) in the gradual reduction group (P = 0.70). Hypothermia: 53% (n = 37) in the cease group and 37% (n = 26) in the gradual reduction group (P = 0.09). The number of hyponatraemic events was similar for both groups (P = 0.73), as for hypernatraemic events (P = 0.3). Skin injury in week 2 of life: 63% in the cease group and 67% in the gradual reduction group (P = 0.72).

Conclusions: Ceasing or gradually reducing incubator humidification after day 7 of life had no effect on the number of episodes of hypothermia or hyperthermia in this cohort of extremely preterm infants (EPTI). There was also no effect on the number of episodes of hyponatraemia or hypernatraemia.

Trial registration: ANZCTR.org.au (Australia New Zealand Clinical Trials Registry). ACTRN 1261 9000 266167 Registered 21/2/2019.

What is known: • Incubator humidification is a widely accepted and routine practice in the management of EPTI as it influences transepidermal water loss (TEWL) and supports thermoregulation. However, weaning practices remain varied and inconsistent across the globe. • There remains a paucity of data to inform specific evidenced-based humidification practices.

What is new: • Ceasing or gradually reducing incubator humidification after 7 days had no effect on temperature stability, serum sodium levels, or frequency of skin injury in this cohort of EPTI between day 8 and day 14. • There is no apparent benefit in prolonging incubator humidity beyond day 7 of life in these EPTI.