Kristen Parker lurks in the OR, watching over her shoulder as the anesthesiologist leaves the room. The 26-year-old surgical tech is alone. Finally. It's been several days between scores, too many hours since she's masked the pain of a failed relationship with the father of her young son. In a quick, practiced stroke, she swipes a fentanyl syringe from the anesthesia cart, replacing it with a needle full of sterile saline solution that she had hidden in her scrub pocket. No one will ever know, she convinces herself, already looking forward to her lunch break, her next opportunity for a quick hit of sweet relief.