Quantitative CT assessment of lung injury after successful cardiopulmonary resuscitation in a porcine cardiac arrest model of different downtimes.

BACKGROUND

Utilize quantitative computed tomography (QCT) to detect and evaluate the severity of lung injury after successful cardiopulmonary resuscitation (CPR) in a porcine cardiac arrest (CA) model with different downtimes.

METHODS

Twenty-one male domestic pigs weighing 38±3 kg were randomized into 3 groups: the sham group (n=5), the ventricular fibrillation (VF) 5 min (VF5) group (n=8), and the VF 10 min (VF10) group (n=8). VF was induced and untreated for 5 (VF5 group) or 10 (VF10 group) min before the commencement of manual CPR. Eight animals (8/8, 100%) in VF5 and 6 (6/8, 75%) in VF10 were successfully resuscitated. Chest QCT scans and arterial blood gas tests were performed at baseline and 6 h post-resuscitation. The QCT score, volume, and weight of ground-glass opacification (GGO), which was defined as poorly aerated regions with a CT value ranging from -500 Hounsfield units (HU) to -100 HU, and intense parenchymal opacification (IPO), which was defined as a non-aerated area with a CT value greater than -100 HU, were quantitatively measured.

RESULTS

Significantly shorter durations of CPR and fewer defibrillations were observed in the VF5 group compared with the VF10 group [duration of CPR: VF5 (6±0 minutes) versus VF10 (8.3±1.5 minutes), P<0.05; numbers of defibrillation: VF5 (1±0) versus VF10 (2.2±0.8), P<0.05]. Compared with the baseline or sham animals, declining gas exchanges (end-tidal CO, PO, oxygen index) were observed in both VF groups; however, there were no significant differences in gas exchanges between the VF groups. Compared with the VF5 group, the GGO QCT score, volume, and weight were significantly greater in the VF10 group (P=0.002, 0.001, and 0.002 respectively), while no significant differences were found in the IPO QCT score, volume, or weight between two the VF groups (P=0.354, 0.447, and 0.512 respectively).

CONCLUSIONS

QCT analysis enables unique non-invasive assessments of different lung injuries (IPO and GGO lesions) that can clearly distinguish heterogeneous lesions and allow for early detection and quantitative monitoring of the severity of lung injury following CPR. QCT could provide a basis for clinical early ventilation strategy management after CPR.