An 81-year-old male complains of abdominal pain and difficulty breathing. He tells you he was stabbed in his abdomen. He has a history of hypertension and high cholesterol. You observe a one-inch laceration just below his xiphoid process. You auscultate diminished lung sounds and bowel sounds in the base of his left lung. His vital signs are P 76, R 20, BP 144/88, and SpO2 is 93. What is the most likely diagnosis?
1) Pneumothorax
2) Pulmonary embolism
3) Perforated viscus
4) Myocardial infarction