Cardiology in Italian

The thirty-second entry is la pressione differenziale, and it is the one quantity on this page whose name an English reader must not carry across word for word. Done literally it gives « differential pressure », which is a real English term belonging to a different trade: in engineering it is the drop measured across a filter, a valve or a membrane, and in a hospital it describes the air balance of an isolation room. The quantity meant here is the systolic reading minus the diastolic one, the gap between la pressione sistolica and la pressione diastolica, and in English that has one name, « pulse pressure ». The two languages have named the same number from opposite ends. Italian names the arithmetic, a difference. English names what a finger feels at the wrist, because it is that gap, and not the height of either reading, that makes the pulse strike hard. Hence una pressione differenziale ampia indica arterie rigide: a wide gap, a hard knock, stiff arteries.