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This thesis is based on four articles originating from three studies conducted in the neonatal intensive care unit and the children’s operating deparment at Uppsala University Hospital, Sweden.

The overall aim was to obtain new knowledge about thermal balance and care environment in extremely preterm infants during skin-to-skin care (SSC), evaluate different methods of intraoperative monitoring of carbon dioxide (CO₂), and to investigate how different levels of inhaled oxygen affect infants’ oxygenation during anesthesia and surgery. Study I investigated infant thermal balance and the physical environment for extremely preterm infants during SSC. Study II formed part of a prospective study to assess the performance of non-invasive transcutaneous and end-tidal technique to continuously monitor CO₂ levels in the infants blood during anesthesia. Study III was a prospective randomized trial to investigate oxygenation during induction of anesthesia with room air versus high fraction (80%) of oxygen in healthy newborn infants.

The infants maintained normal body temperature during SSC. In comparison to care in an incubator, during SSC ambient humidity was lower and insensible water loss through the skin was higher. Compared to blood gas Pco_2­, transcutaneous carbon dioxide monitoring yielded a bias of 0.3 ± 0.7 kPa, and end-tidal technique a bias of -1.9 ± 0.9 kPa. After intubation, saturation measured by pulse oximetry was lower (p < .05) in the group breathing room air than in the group with high oxygen (93% ± 6.7 and 99% ± 1.5). None of the infants spent time below the pre-specified safety oxygen saturation targets to mandate supplemental oxygen.

This thesis provides new knowledge about early initiation of SSC after birth for extremely preterm infants, the results will be useful to guide safe routines for implementation of early SSC. These results suggest that during anesthesia would transcutaneous monitoring of carbon dioxide be beneficial, end-tidal monitoring correlated poorly to blood gas and induction of general anesthesia in newborn infants can be safely performed without the use of high levels of supplemental oxygen. Taken together, this new knowledge has the potential to improve intraoperative respiratory management.