Page 419 - Critical Care Nursing Demystified

404 CRITICAL CARE NURSING DeMYSTIFIED

is an assault on the endothelial lining from inside the body (intrinsic) or from
outside (extrinsic), pathways are initiated that start a cascade of events to pro-
duce hemostasis.
Injury to the vessel results in muscular spasm also releasing neural reflexes
and humoral factors. Platelets start “clumping” together adhering to the site of
injury and each other with spinylike projections. A plug of platelets forms,
stimulating the clotting cascade.
Thromboplastin is released from damaged tissues, activating numerous steps
until prothrombin activator is produced. The amount of prothrombin activator
released is directly proportional to the amount of tissue damaged. Prothrombin
activator changes prothrombin to thrombin, which in turn leads to fibrin for-
mation. Fibrin is the gel that holds together the platelets and other blood com-
ponents. The thrombus or blood clot usually stays on site but may break away
and embolize.
Further strengthening of the clot occurs as fibroblasts invade the meshwork
of the clot. Next, the clot retracts, pulling its edges together and further pro-
tecting the injury. Almost immediately, the body starts breaking apart the
thrombus by a process of fibrinolysis. The end result is healing of the injury,
smoothing of the endothelial lining, and reestablishment of blood flow. Downloaded by [ Faculty of Nursing, Chiangmai University 5.62.158.117] at [07/18/16]. Copyright © McGraw-Hill Global Education Holdings, LLC. Not to be redistributed or modified in any way without permission.

2 Steps in Hemostasis

Injury to the endothelial wall
Platelet aggregation
Activation of clotting cascade
Release of thromboplastin
Creation of prothrombin activator
Changing of prothrombin to thrombin
Production of fibrin and clot formation
More clotting occurs, further strengthening the clot with fibroblasts
Thrombus retraction occurs
Thrombus starts fibrinolysis
Healing and reestablished blood flow

Assessment Skills

3 Observation and care of the patient with hematologic disorders involve
looking for signs and symptoms of bleeding, infection, or anemia.