| Autor: |
Diedericks C; The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, Victoria, Australia.; Department of Obstetrics and Gynaecology, Monash University, Melbourne, Victoria, Australia., Crossley KJ; The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, Victoria, Australia.; Department of Obstetrics and Gynaecology, Monash University, Melbourne, Victoria, Australia., Davies IM; The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, Victoria, Australia.; Department of Obstetrics and Gynaecology, Monash University, Melbourne, Victoria, Australia., Riddington PJ; The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, Victoria, Australia.; Department of Obstetrics and Gynaecology, Monash University, Melbourne, Victoria, Australia., Cannata ER; The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, Victoria, Australia.; Department of Obstetrics and Gynaecology, Monash University, Melbourne, Victoria, Australia., Martinez OL; The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, Victoria, Australia.; Department of Obstetrics and Gynaecology, Monash University, Melbourne, Victoria, Australia., Thiel AM; The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, Victoria, Australia.; Department of Obstetrics and Gynaecology, Monash University, Melbourne, Victoria, Australia., Te Pas AB; Division of Neonatology, Department of Paediatrics, Leiden University Medical Centre, Leiden, The Netherlands., Hooper SB; The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, Victoria, Australia.; Department of Obstetrics and Gynaecology, Monash University, Melbourne, Victoria, Australia. |
| Abstrakt: |
Airway liquid is cleared into lung tissue after birth, which becomes edematous and forces the chest wall to expand to accommodate both the cleared liquid and incoming air. This study investigated how changing chest wall mechanics affects respiratory function after birth in near-term lambs with different airway liquid volumes. Surgically instrumented near-term lambs (139 ± 2 days) were randomized into Control ( n = 7) or Elevated Liquid (EL; n = 6) groups. Control lambs had lung liquid drained to simulate expected volumes following vaginal delivery. EL lambs had airway liquid drained and 30 mL/kg liquid returned to simulate expected airway liquid volumes after elective cesarean section. Lambs were delivered, transferred to a Perspex box, and ventilated (30 min). Pressure in the box was adjusted to apply positive (7-8 cmH 2 O above atmospheric pressure) or negative (7-8 cmH 2 O below atmospheric pressure) pressures for 30 min before pressures were reversed. External negative pressures expanded the chest wall, reduced chest wall compliance ( C CW ) and increased lung compliance ( C L ) in Control and EL lambs. External positive pressures compressed the chest wall, increased C CW and reduced C L in Control and EL lambs. External negative pressure improved pulmonary oxygen exchange, reducing the alveolar-arterial difference in oxygen (AaDO 2 ) by 69 mmHg (95% CI [13, 125]; P = 0.016) in Control lambs and by 300 mmHg (95% CI [233, 367]; P < 0.001) in EL lambs. In contrast, external positive pressures impaired pulmonary gas exchange, increasing the AaDO 2 by 179 mmHg (95% CI [73, 285]; P = 0.002) in Control and by 215 mmHg (95% CI [89, 343]; P < 0.001) in EL lambs. The application of external thoracic pressures influences respiratory function after birth. NEW & NOTEWORTHY This study investigated how changes in chest wall mechanics influence respiratory function after birth. Our data indicate that the application of continuous external subatmospheric pressure greatly improves respiratory function in near-term lambs with respiratory distress, whereas external positive pressures impair respiratory function. Our findings indicate that, during neonatal resuscitation at birth, the forces applied to the chest wall should not be ignored as they can have a major impact on neonatal respiratory function. |
