Page 105 - Physiological based CPAP for preterm infants at birth Tessa Martherus

Part II: Changing CPAP Levels
High-CPAP does not impede cardiovascular changes at birth in preterm sheep
On 5/9 (56%) occasions, caffeine improved breathing and increased mean PBF. On the 10/13 (77%) occasions that iPPV was deemed successful, the first inflation was transmitted to the lungs after 4 (2-29) s and increased breathing rate, mean PBF, heart rate, SaO2, and AaDO2 (Table 3). In 3/13 (23%) animals, ventilation did not reach the lungs and intubation was required Reducing CPAP from 15 to 8 or from 15 to 5 cmH2O, increased the FiO2 requirement, without affecting mean PBF, CBF or any of the blood gas parameters (Figure 6 and Table 4). Increasing CPAP from 5 to 15 cmH2O, reduced the FiO2 requirement and resulted in a small (~10%) but statistically significant decrease in mean PBF that took ~5 min to manifest (Figure 6). Increasing CPAP levels had no effect on CBF, breathing rate, PaCO2, and SaO2 (Table 4).
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Figure 6. Effect of changing CPAP levels. Changes in a-c) pulmonary blood flow (PBF, median (Q1-Q3)) and b-f) fraction of inspired oxygen (FiO2, median (Q1-Q3)) measured in response to changes in CPAP levels from 15 to 8 cmH2O within 30 minutes after birth (a and d) and from 15 to 5 cmH2O (b and e) or 5 to 15 cmH2O (c and f) at 30 minutes after birth. Parameters were compared over time using Friedman’s tests. T=0 indicates the start of CPAP change.
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