Pelvic Ring Injuries

The pathophysiology of pelvic ring injuries: a review

“…The question of whether a trauma patient is in “hidden shock” is addressed by clinical parameters, laboratory testing, and imaging studies, as outlined further below. The bleeding trauma patient’s oxygen requirement is illustrated by the historic Nunn & Freeman formula from 1964: O2 av = CO × SaO 2 × Hb × 1.34 [ 33 ]. This equation clarifies that the available tissue oxygen (O2 av ) is equal to the product of cardiac output (CO in ml/min), arterial oxygen saturation (SaO 2 in %) and hemoglobin concentration (Hb in g%), whereby the Nunn-Freeman constant of 1.34 represents the O2-binding capacity of hemoglobin (in ml/g) [ 33 ].…”

“…The bleeding trauma patient’s oxygen requirement is illustrated by the historic Nunn & Freeman formula from 1964: O2 av = CO × SaO 2 × Hb × 1.34 [ 33 ]. This equation clarifies that the available tissue oxygen (O2 av ) is equal to the product of cardiac output (CO in ml/min), arterial oxygen saturation (SaO 2 in %) and hemoglobin concentration (Hb in g%), whereby the Nunn-Freeman constant of 1.34 represents the O2-binding capacity of hemoglobin (in ml/g) [ 33 ]. While the oxygen demand and supply is generally met under physiological conditions, the underlying variables of the Nunn-Freeman formula are dramatically compromised in multiply injured patients due to acute blood loss (Hb), pulmonary contusions (SaO 2 ), and myocardial contusion or pericardial tamponade (CO), resulting in a limiting deficit of systemic oxygen supply [ 33 ].…”