Shulchan Arukh, Yoreh De'ah 26/שולחן ערוך·יורה דעה כ״ו

1Seif 1 If there is a puncture in the esophagus during the slaughter and its the opposite the spot of slaughter, its considered Torn (not acceptable).

2Seif 2 While one is slaughtering the gullet/esophagus and one finds that the lungs are punctured before he was able to slaughter the gullet, or if while one is slaughtering the gullet/esophagus and one finds that intestines are punctured before he was able to slaughter the gullet, it is considered Torn (It's unacceptable).