A fifty-eight-year-old client with poorly controlled hypertension arrives with severe chest pain that began abruptly while lifting a suitcase. He describes it as tearing, says it started between his shoulder blades and has since moved lower. His right arm pressure is 178/96 mmHg. His left arm pressure is 132/78 mmHg. That forty-six-point difference between arms is not an equipment error, and it is the finding most likely to be dismissed as one. An aortic dissection begins when the innermost lining of the aorta tears. Blood at arterial pressure is driven into the wall itself, splitting the layers apart and creating a second, false channel that travels along the vessel. Every branch artery the false channel crosses can be pinched shut — which is why one client presents with a stroke, another with a cold leg, another with abdominal pain, and another with kidney failure, all from the same event. This is one of the few conditions where the correct nursing action runs opposite to instinct. The client is in agony and hypertensive, and the temptation is to treat the pain...