A young woman sustains a severe head injury as the result of a motor vehicle crash. In the emergency department, her GCS is 6. Her blood pressure is 140/90 mm Hg and her heart rate is 80 beats per minute. She is intubated and mechanically ventilated. Her pupils are 3 mm in size and equally reactive to light. There is no other apparent injury. The most important principle to follow in the early management of her head injury is to: {Ans: avoid hypotension}A 22-year-old female athlete is stabbed in her left chest at the third interspace in the anterior axillary line. On admission to the emergency department and 15 minutes after the incident, she is awake and alert. Her heart rate is 100 beats per minute, blood pressure 80/60 mm Hg, and respiratory rate 20 breaths per minute. A chest x-ray reveals a large left hemothorax. A left chest tube is placed with an immediate return of 1600 mL of blood. The next management step for this patient is: {Ans: prepare for an exploratory thoracotomy}A hemodynamically normal 10-year-old girl is hospitalized for observation after a Grade III (moderately severe) splenic injury has been confirmed by computed tomography (CT).