Page 79 - Physiological based CPAP for preterm infants at birth Tessa Martherus

Higher CPAP levels improve functional residual capacity at birth in preterm rabbits
The incidence of lung bulging between the ribs (p=0.159), pneumothorax (p=0.347), and CPAP belly (p=0.756) were not different between groups (Table 2). Due to technical problems, there were insufficient data acquired to analyse the ECG and pulse oximeter measurements to compare heart rate or oxygen saturation.
Rescue interventions
P
During apnoea, prior to the start of IPPV, kittens (from all groups) had FRC values ranging from 0.4 to 15.5 mL/kg. Following the use of rescue interventions (IPPV and tactile stimulation if necessary), both FRC (median (Q1-Q3) before vs after, 1.3 (0.7-8.9) to 15.5 (9.4-21.2) mL/kg, p <0.001) and breathing rates (4 (1-9) to 41 (26-48) breaths/min, p <0.001) were significantly increased.
In total, 42% of the kittens that became apnoeic, started breathing during IPPV without any stimulation. The remaining 58% required tactile stimulation to end apnoea and they received
IPPV for 1.14 (0.44-2.10) min before tactile stimulation commenced. Tactile stimulation was 3 successful in terminating apnoea and re-establishing breathing within 17 (15-20) s. In all
kittens who required tactile stimulation in addition to IPPV, FRC only increased after they
received tactile stimulation and had recommenced breathing.
Changing CPAP levels
In the dynamic CPAP groups, respiratory support was initiated with 15 cmH2O and CPAP was then decreased to 5 and 8 cmH2O after 5:26 (2:53-6:16) and 4:01 (3:01-4:36) min, respectively. Decreasing CPAP from 15 to 5 cmH2O significantly decreased FRC from 17.5 (16.5-20.2) before change to 15.4 (13.6-18.6) mL/kg (median (Q1-Q3) up to 2 min after the end of the CPAP decrease (χ2 (3) = 14.127, p=0.003, Figure 5a). Similarly, breathing rates were reduced significantly from 40 (26-49) to 27 (14-42) breaths/min at 3 min after the CPAP had been decrease to 5 cmH2O (χ2 (4) = 14.922, p=0.005, Figure 5b). Decreasing CPAP levels from 15 to 8 cmH2O did not reduce FRC (18.9 (4.1-23.4) to 19.8 (12.4-23.2) mL/kg, χ2 (4) = 3.437, p=0.487, Figure 5a) or breathing rates (35 (30-40) to 37 (35-46) breaths/min, χ2 (4) = 6.210, p=0.184, Figure 5b).
At the end of the experimental period, there were no differences in FRC when comparing the continuous 15 cmH2O (20.5 (14.2-24.5) mL/kg) CPAP and dynamic 15 to 5 cmH2O (18.7 (5.6-22.6) mL/kg) and 15 to 8 cmH2O (18.2 (14.2-22.1) mL/kg) CPAP strategies (p=0.518, Figure 5c). However, final breathing rates were 26 (11-41) breaths/min in the 15 to 5 cmH2O group, compared to 34 (28-48) breaths/min in the 15 cmH2O and
40 (35-48) breaths/min in the 15 to 8 cmH2O CPAP groups (p=0.059, Figure 5d) at experiment end.
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