THE CONTRIBUTION OF SOFT-TISSUE TRAUMA AN D OR BONE-FRACTURE TO DEPRESSED IMMUNITY FOLLOWING HEMORRHAGIC-SHOCK IN AN EXPERIMENTAL SETTING/

Bone fracture, soft-tissue trauma and hemorrhagic shock are frequent c omplications in trauma patients, and these patients are known to be im munocompromised. Nonetheless, it is difficult to differentiate the eff ect of soft-tissue trauma plus hemorrhage from that of bone fracture a nd hemorrhage on host immune function in the clinical setting. To dete rmine this experimentally, closed bone fracture (right lower leg) and/ or soft-tissue trauma (2.5 cm midline laparotomy) were induced prior t o hemorrhagic shock (mean arterial BP of 35 +/- 5 mm Hg for 90 min) in male C3H/HeN mice. All animals were killed al 72 h after initiation o f the experiment and the spleens were collected aseptically. More sign ificant depression of splenocyte IL-2 and IL-3 release occurred with t he combined insult than after bony injury or tissue trauma alone with hemorrhage. The present study suggests that different traumatic insult s, i.e. bone fracture as well as soft-tissue trauma in conjunction wit h hemorrhagic shock, produce comparable depression of host immune func tion. Moreover, combination of closed bone fracture and soft-tissue tr auma prior to hemorrhagic shock leads to even more compromised immunit y. This indicates that different mechanisms of immune depression may b e involved following soft-tissue trauma or bony injury coupled with he morrhage. The markedly depressed immune function following bony injury , soft-tissue trauma and hemorrhagic shock may contribute to the incre ased susceptibility of severely injured patients to sepsis and the ens uing multiple organ failure in the clinical situation.