Page 106 - Physiological based CPAP for preterm infants at birth Tessa Martherus

Chapter 4
Table 4. Effect of changing CPAP levels
15 to 8 cmH2O
15 to 5 cmH2O
CBF (mL/min)
Breathing rate (bpm)
PaCO2 (mmHg)
SaO2 (%)
66 (51-90) to
71 (67-77) mL/min, ꭕ2 (12)=0.74, p=0.805
66 (35-91) to
60 (52-64) bpm,
ꭕ2 (12)=14.14, p=0.292
133.0 (79.4-169.3) to 149.1 (80.4-186.3) mmHg, ꭕ2 (2)=3.68, p=0.159
92 (87-95) to
86 (53-94) %,
ꭕ2 (2)=1.00, p=0.607
86 (38-91) to
71 (37-101) mL/min, ꭕ2 (12)=4.88, p=0.962
74 (67-127) to
70 (63-109) bpm,
ꭕ2 (12)=17.99, p=0.116
60.8 (56.8-94.9) to 60.2 (45.9-81.5) mmHg, ꭕ2 (2)=4.50, p=0.105
91 (81-93) to
85 (83-96) %,
ꭕ2 (2)=1.50, p=0.472
(59 (46-89) to
55 (51-69) mL/min, ꭕ2 (12)=7.01, p=0.857
48 (36-88) to
80 (79-81) bpm,
ꭕ2 (12)=7.91, p=0.792
81.4 (68.0-97.5) to 76.1 (63.0-96.0) mmHg, ꭕ2 (2)=1.00, p=0.607
(88 (78-90) to
85 (59-96) %,
ꭕ2 (2)=4.00, p=0.135
(n=9) (n=5) (n=7)
Data is presented as median (Q1-Q3) before change vs 6 minutes after change.
Discussion
This is the first study to investigate the effect of high-CPAP, applied non-invasively, on cardiorespiratory function at birth in spontaneously breathing animals. Contrary to our hypothesis, high-CPAP did not impede the normal increase in PBF at birth, nor reduce CBF or increase JVP in spontaneously breathing preterm sheep immediately after birth. Instead, high-CPAP resulted in higher PBF, heart rate and BAP compared to low-CPAP, while showing no effect on CBF, CBF variability or the incidence of pneumothoraces. The increased mean and end-diastolic PBF also indicates that HCPAP lambs sooner achieved a lower PVR compared to the LCPAP lambs, that was substantially lower than the systemic venous resistance. While CPAP levels had little impact on JVP, large fluctuations in JVP were observed in all groups and were associated with active expirations that involved the use of expiratory muscles (mostly abdominal). In addition, lambs receiving high-CPAP had a higher breathing rates, tended to receive fewer rescue interventions and required significantly fewer intubations. Overall, high-CPAP was more successful in supporting preterm lambs throughout the neonatal transition at birth. After stabilization, reducing the CPAP level from 15 to 8 cmH2O resulted in a higher FiO2 requirement, while increasing the CPAP level from 5 to 15 cmH2O reduced the FiO2 requirement, but also caused a small reduction in PBF. Thus, we found no evidence to indicate that the use of high-CPAP immediately after birth causes pulmonary overexpansion (as indicated by a reduction in PBF) or compromises the cardiovascular system. As high-CPAP
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5 to 15 cmH2O