Complex sentence: During his return trip he caught a cold which, compounded by the lingering effects of his stabbing and complications from kidney disease, led to Isaac Cody's death in April, 1857.
Split into simpler sentences: During his return trip he caught a cold, which he eventually died from. The combination of his stab wound, that he never fully recovered from, and complications from kidney disease became too much and he died in April, 1857.