IMAGING LUNG AERATION AND LUNG LIQUID CLEARANCE AT BIRTH USING PHASE CONTRAST X-RAY IMAGING

• 1 The transition to extra‐uterine life at birth is critically dependent on airway liquid clearance to allow the entry of air and the onset of gaseous ventilation. We have used phase contrast X‐ray imaging to identify factors that regulate lung aeration at birth in spontaneously breathing term and mechanically ventilated preterm rabbit pups.
• 2 Phase contrast X‐ray imaging exploits the difference in refractive index between air and water to enhance image contrast, enabling the smallest air‐filled structures of the lung (alveoli; < 100 µm) to be resolved. Using this technique, the lungs become visible as they aerate, allowing the air–liquid interface to be observed as it moves distally during lung aeration.
• 3 Spontaneously breathing term rabbit pups rapidly aerate their lungs, with most fully recruiting their functional residual capacity (FRC) within the first few breaths. The increase in FRC occurs mainly during individual breaths, demonstrating that airway liquid clearance and lung aeration is closely associated with inspiration. We suggest that transpulmonary pressures generated by inspiration provide a hydrostatic pressure gradient for the movement of water out of the airways and into the surrounding lung tissue after birth.
• 4 In mechanically ventilated preterm pups, lung aeration is closely associated with lung inflation and a positive end‐expiratory pressure is required to generate and maintain FRC after birth.
• 5 In summary, phase contrast X‐ray imaging can image the air‐filled lung with high temporal and spatial resolution and is ideal for identifying factors that regulate lung aeration at birth in both spontaneously breathing term and mechanically ventilated preterm neonates.

     

Clinicopathologic features of antineutrophil cytoplasm autoantibody (ANCA)-associated acute renal failure in Chinese patients

Summary: The clinical course and renal pathologic features of anti-neutrophil cytoplasm auto-antibody (ANCA)-associated renal disease were studied among Chinese patients from a single centre. Eight ANCA positive patients with acute renal impairment were studied, four of whom required dialysis shortly after presentation. Their mean age at presentation was 61.6 ± 4.2 years. Renal histology, obtained in seven patients, showed paucummune crescentic glomerulonephritis in five patients, interstitial nephritis in two patients, and small vessel vasculitis in one patient. Pulmonary baemorrhage was the other common disease manifestation, present in four of the eight patients, necessitating ventilatory support in three patients. Neurologic, cutaneous, and gastrointestinal involvement were also observed. Seven of the eight patients tested positive for pANCA and anti-myeloperoxidase, while cANCA was detected in one patient of the eight patients, six (75%) responded to therapy, consisting of prednisolone and cyclophosphamide in five patients, and antibacterial therapy alone in one patient, who had interstitial nephritis but no evidence of vasculitis. Two patients died from sepsis and severe debilitation one month after presentation. of the other six patients, five had significant improvement of renal function, while one became dialysis-dependent. the levels of ANCA and C-reactive protein remained normal, and disease reactivation was not observed during follow-up for 32.4 ± 6.1 months. Patient and renal survival rates at one year were 75% and 62.5%, respectively. It was concluded that the clinical and pathologic features of ANCA-associated renal disease in Chinese patients are, in general, similar to those described in Caucasians. Nevertheless, cANCA-positivity is distinctly uncommon. the demonstration of interstitial nephritis in two of the eight patients underlines the importance of renal biopsy for correct histologic diagnosis. Early institution of aggressive immunosuppression and supportive therapies are essential for the achievement of favourable outcome in patients with vasculitis.