The large diameter of the bullet caused the substantial damage however, it is not a fatal wound because the bullet didn't hit any veins or arteries. Treatment did require extensive surgery and intestinal repair. Any perforation of small or large intestine will cause contamination of the abdominal cavity, and immediate surgery to prevent infection is required. The Pope was shot several years ago and received this type of injury. Any bullet wound to a lung will cause hemorraging into the lung cutting the oxygen supply to the body.
Most people can survive a hit to one lung.
If both lungs are hit, there is a very high probability of death within a short period of time. The more damage to the lung, the larger the diameter of the bullet, the faster the blood loss. Lung wounds are seldom, if ever, a cause for an immediate stopping of an assailant. In fact, after being shot through both lungs, a person could still be aggressive for several minutes. This lung has been hit by an expanded 9mm bullet and the resulting wound is difficult to see the difference between a hollowpoint and a non-expanding bullet.