Objective To observe the protective effect of Shenfu Injection ( SFI) on post-resusci- tation lung injury in a porcine model of asphyxia-induced cardiac arrest. Methods Thirty-four anaesthe- tized Wuzhi Mountain inbred miniature piglets of both sexes were subjected to asphyxia by intubation clip- ping, followed by standard cardiopulmonary resuscitation. Eighteen successfully resuscitated pigs [with recovery of return of spontaneous circulation ( ROSC) ] were divided into the SFI group and the normal saline (NS) group according to random digit table, 9 in each group. SFI at 0. 24 mg/min was intravenously pumped to piglets in the SFI group immediately from ROSC to 6 h after resuscitation, while NS at 0. 24 mg/min was intravenously pumped to piglets in the NS group immediately from ROSC to 6 h after resusci- tation. Oxygen metabolism, respiratory mechanics indices including oxygenation index (ΟI) , respiration index ( RI) , oxygen delivery ( DO₂), oxygen consumption ( VO₂), oxygen extraction ratio (Ο₂ ER), PaCO₂, lactic acid (LAC) were detected using blood gas analyzer at basic state, immediately after ROSC, 15 and 30 min, 1, 2, 4, and 6 h after ROSC. Dynamic lung compliance (Cdyn) , airway resistance (Raw), external vascular lung water index (EVLWI) , pulmonary vascular permeability index (PVPI) were monitored at each aforesaid time point. Activities of Na+-K +-ATPase and Ca² +-ATPase, contents of SOD and MDA, concentrations of TNF-α, IFN-γ, and IL-4 were determined using ELISA.IFN-γ/IL-4 ratio was calculated. Cell apoptosis was detected using TUNEL and apoptotic index (Al) calculated. Protein concentrations of Bcl-2 and Bax were detected using immunohistochemical assay, and Bax/Bcl-2 ratio calculated. Caspase-3 protein was quantitatively detected using Western blot. Results The survival rate was 88. 9% (8/9) in the SFI group and 66. 7% (6/9) in the NS group at 6 h after ROSC. The mean survival time was (5. 77 ±0. 71) h in the SFI group, longer than that in the NS group [ (4. 77 ±0. 59) h, P >0. 05]. Compared with the basic state, 01 and Cdyn obviously decreased immediately after ROSC (P <0. 05) ; RI, DO₂, VΟ₂, O₂ER, Raw, EVLWI, PVPI, PaCO₂, and LAC obviously increased immediately after ROSC (P<0. 05). All indices were recovered as time went by. Compared with the NS group, ΟI, Cdyn, DO₂, VΟ₂, and Ο₂ ER at each time points after ROSC were significantly higher in the SFI group than in the NS group (P <0. 05, P <0. 01); RI, Raw, EVLWI, PVPI, PaCO₂, and LAC were significantly lower in the SFI group than in the NS group (P <0. 05, P <0. 01 ). Compared with the NS group, activities of Na'-K '-AT- Pase and Ca² +-ATPase, contents of SOD, level of IFN-γ, IFN-γ/IL-4 ratio, concentrations of Bcl-2 in- creased more; MDA, TNF-α, IL-4 level, Al, Bax/Bcl-2 ratio, Caspase-3 protein level decreased more (P <0. 05, P <0. 01). Conclusion SFI could improve cell energy metabolism, enhance antioxidant ca- pacity of cells, reduce the release of inflammatory mediators, regulate the Thl/Th2 balance, and attenu- ate cell apoptosis of lung tissue, thereby protecting post-resuscitation lung injury.