COMPENSATED SHOCK
Compensated shock can start with low normal blood pressure: a condition called
"normotensive, cryptic shock"
Many physicians fail tot recognize the early part of this stage: "he/she does not look right"... and "I don't know what is going on", "and the the blood pressure is not too bad"...
Note: normotensive or hypertensive shocks are not mentioned in major cardiology textbooks ! (see references).

The proof that a patient is in shock with normal blood pressure is the appearance of metabolic acidosis due to some organ hypoperfusion.
The reason for normotension (or even hypertension in some cases) is that blood pressure is maintained initially thanks to marked activation of many compensatory mechanisms (including the sympathetic nervous system). However, because organs suffer from inadequate perfusion, it is already a state of shock.