Use of manual alveolar recruitment maneuvers to eliminate atelectasis artifacts identified during thoracic computed tomography of healthy neonatal foals.

The study looks into the use of alveolar recruitment maneuvers (ARMs) to reduce lung atelectasis (collapse or closure of a lung) during Computed Tomography (CT) scans of anaesthetized healthy newborn foals. It was observed that ARMs did not completely eliminate atelectasis, but they lessened attenuation, particularly in the nondependent part of the lungs.

Study Approach

• The study involved six neonatal Standardbred foals. Thoracic CT was carried out on these spontaneously breathing, anesthetized foals when they were positioned in sternal (3 foals) or dorsal (3 foals) recumbency at different ages – 24 to 36 hours, 4 days, 7 days, and 10 days old.
• CT images were collected at all these times both with and without ARMs and with different internal airway pressures of 10, 20, and 30 cm HO (only at times 2 and 3).
• The CT images were then subjected to quantitative analysis to measure lung changes in attenuation or volume with the use of ARMs.

Study Findings

• The study found that increased attenuation and an alveolar pattern appear more prominently in the dependent part of the lungs.
• While ARMs could not entirely eliminate atelectasis, they reduced attenuation, particularly in the nondependent portion of the lungs of foals.
• Notably, the study did not identify any significant lung attenuation differences based on the position of the foal.
• The use of ARMs decreased lung attenuation while it increased lung volume. Both these effects were significant (only at times 2 and 3) and more pronounced in the nondependent portion of the lungs and at ARMs of 20 and 30 cm HO.

Clinical implications

• The findings of the study indicate that while manual ARMs do not eliminate atelectasis completely, they help lower attenuation, especially in nondependent parts of the lungs.
• Therefore, for clinical purposes, it may be advisable to position foals in dorsal recumbency during CT scans when pathological changes in the ventral (lower) portion of the lungs are suspected.