Effect of epidural analgesia on immediate posttraumatic cardiovascular hemodynamics and pulmonary platelet trapping

Immediate reactions to different types of trauma have been the object of several studies recently. Thus, it has been shown that pulmonary platelet trapping (PPT) occurs within minutes after both septic and traumatic shock following soft tissue trauma. To study whether block of the nervous supply to the traumatized tissue had any effect on PPT, 40 mg of mepivacaine was injected through an epidural catheter inserted between the second and third lumbar vertebrae in pigs. After a period of stabilization the animals were subjected to a standardized soft tissue trauma to the hind limbs. A group of animals without an epidural catheter served as control. The trauma induced a profound decrease in cardiac output and mean arterial pressure. Pulmonary platelet trapping was recorded dynamically by labelling platelets with radioactive indium. Trapping of platelets in the lungs occurred immediately after the trauma, and there was no difference in animals pretreated with epidural block compared with the control animals. Our findings indicate that the trapping of platelets after soft tissue trauma is triggered at the trauma site and not affected by a block of the nervous supply to the trauma sites, including the peripheral sympathetic outflow.