Permissive hypotension is a doctrine of modern trauma medicine, the seemingly counterintuitive practice that resuscitation should not raise an injured victim's blood pressure to normal levels, before definitive surgery. The goal, instead, is to raise it high enough to ensure oxygen perfusion of the brain, but no higher. Normal systolic blood pressures have been found to disrupt blood clots that have stopped bleeding from the injury, and restart life-threatening hemorrhage.
As a rule of thumb, the systolic pressure should not exceed 80-100 mm (or 75% of the pre-injury level), but the exact target must be part of clinical assessment of the patient. There are exceptions, such as the need to fluid-load a patient pinned under a heavy weight, before the pressure is released, or quite possibly have the patient die in seconds to minutes due to the physiologic derangements of crush injury.