Oxygen is a critical component of the microenvironment required for supporting cellular activities. Tissue oxygen alteration is a vital sign for the assessment of cardiovascular diseases such as heart failure, septic shock, and cerebral hypoxia.^{1 – 3} Tissue oxygenation level reflects the balance between oxygen supply and consumption.⁴ Blood flow affects the efficiency of oxygen delivery to and waste removal from tissues. Blood flow is highly sensitive to pathophysiological alterations,⁵ thus could be an indicator for the detection of diseases that are associated with tissue ischemia such as peripheral artery disease, cerebral vascular disease, neurological disorders, and cancers.^{6 – 11} There are also growing interests in simultaneous measurements of blood flow and oxygenation alterations as more comprehensive biomarkers for tissue health/injury than one single parameter alone.^{12 – 14} Furthermore, a combination of tissue blood flow and oxygenation allows to estimate the metabolic rate of tissue oxygen consumption,^12,15 another important functional parameter highly associated with tissue pathology.

BACKGROUND: A recent multinational clinical trial in preterm infants has demonstrated pulmonary and neurodevelopmental benefits from caffeine therapy. Indications for caffeine use in that study were predominantly for treatment of apnea and facilitati

Intermittent hypoxaemia (IH) events are well described in extremely preterm infants, but the occurrence of IH patterns in more mature preterm infants remains unclear. The objective of this study was to characterise the effect of gestational age on early postnatal patterns of IH in extremely (<28 weeks), very (28–<32 weeks) and moderately (32–<34 weeks) preterm infants. As expected, extremely preterm infants had a significantly higher frequency of IH events of longer durations and greater time with hypoxaemia versus very and moderately preterm infants. In addition, the postnatal decrease in IH duration was comparable in the very and moderately preterm infants. This progression of IH events should assist clinicians and families in managing expectations for resolution of IH events during early postnatal life.

Objective A major consequence of prematurity is intermittent hypoxemia (IH). Data from both adult studies and neonatal animal models suggest that IH is proinflammatory; however, there is limited data in preterm infants. Here, we assess the relationship between IH and systemic inflammation, namely, serum C-reactive protein (CRP) in preterm infants. Study Design Serum CRP was measured at 30 days of life, at the time of peak IH frequency. IH measures (e.g., per cent time in hypoxemia, frequency, duration) were calculated the week prior to CRP collection. Statistical analyses were based on Spearman's correlation. Results A total of 26 infants were included. Median gestational age and birth weight were 27^4/7 weeks and 980 g, respectively. There were positive correlations between primary IH measures and CRP levels, especially for events longer than 1-minute duration (r range: 0.56–0.74, all p < 0.01). Conclusion We demonstrate that IH is associated with increased CRP for the first time in preterm infants. Our findings are consistent with studies from adults and neonatal animal models suggesting that IH is a proinflammatory process. Key Points

Currently, the administration of surfactant to preterm infants with respiratory distress syndrome (RDS) mainly relies on intratracheal instillation; however, there is increasing evidence of aerosolized surfactant being an effective non-invasive strategy. We present a historical narrative spanning sixty years of development of aerosolization systems. We also offer an overview of the pertinent mechanisms needed to create and manage the ideal aerosolization system, with a focus on delivery, distribution, deposition, and dispersion in the context of the human lung. More studies are needed to optimize treatment with aerosolized surfactants, including determination of ideal dosages, nebulizer types, non-invasive interfaces, and breath synchronization. However, the field is rapidly evolving, and widespread clinical use may be achieved in the near future.