Trauma systems, resuscitation & damage control: a free FRCS (Gen Surg) Section 1 question

Children compensate for haemorrhage by tachycardia and intense peripheral vasoconstriction, so systolic pressure is preserved until a large proportion of the blood volume has been lost: ATLS teaches that it may not fall until 30% has gone, and that frank hypotension signifies decompensated shock with loss of around 45%, shortly before bradycardia and arrest. This boy is already in compensated shock. Narrowing of the pulse pressure, weak or absent peripheral pulses, cool mottled limbs with prolonged capillary refill, and oliguria are all earlier consequences of vasoconstriction and reduced organ perfusion, and should trigger blood-product resuscitation and a search for the source. Reference: ATLS Student Course Manual, 10th edition (2018), chapter on trauma in children.