Page 409 - Fluid, Electrolyte, and Acid-Base Disorders in Small Animal Practice

Monitoring Fluid Therapy and Complications of Fluid Therapy 399

Coagulopathy stopped. Fluid resuscitation then can occur to optimal
In addition to the above concerns for clot strength with requirements without concern of further blood loss.
aggressive fluid administration, trauma patients with
blood loss receiving a large volume of crystalloid and col- Autotransfusion of Blood
loid fluids to raise blood pressure are at great risk for Autotransfusion of blood, in the peracute setting, from
dilutional and dysfunctional coagulopathy. 44,81 In addi- the thorax or abdomen can be lifesaving in an
tion, the shock state plus room temperature fluids result exsanguinating animal if no other source of hemoglobin
in hypothermia. Acidosis often is present in such patients, is available. However, one should anticipate serious
and is made markedly worse by the use of normal saline. complications that will arise if blood is autotransfused
This combination enhances the loss and function of coag- from abdominal hemorrhage of several hours duration
ulation factors with the inevitable exacerbation of bleed- or associated with intestinal or colonic injury and leakage
ing. As noted in the colloid section, hydroxyethyl starch of contents, or that which has occurred as a result of neo-
may augment problems with hemostasis. Hetastarch plasia. Frequently, hemorrhage associated with neoplasia
(670/0.75) has been shown to alter platelet function in does not represent a single episode of bleeding but rather
healthy dogs, which may increase the risk of bleeding. 77 one of several with some episodes of hemorrhage occur-
To avoid, or reduce, the coagulopathic complications ring days to weeks previously. Various metabolic products
associated with fluid administration, appropriate blood in this accumulated blood are triggers for disseminated
products, such as whole blood, warm balanced electrolyte intravascular coagulation even when filtered. The poten-
fluids, and a calculated volume of synthetic colloid (see tial for facilitating metastatic spread of the tumor also is
Chapter 27) should be administered. As a guide for frequently debated.
requirement for fresh frozen plasma or fresh blood,
ongoing monitoring and assessment of hemostatic func- Approach to Fluid Selection and Volume to Avoid
tion is essential. Periodic measurement of the activated Complications
clotting time using a tissue activator (i.e., tubes The volume of fluid to be administered is dependent on
containing celite or kaolin [The Actalyke Story. The Sci- the situation at hand. The cause and severity of the
ence. Helena Laboratories, Beaumont, Tex. 1997].) is a hypovolemic state are important factors in fluid (e.g.,
very cheap test, and was prolonged in hemorrhage, hypo- crystalloid, colloid, blood products) selection and volume
thermia, and combined hypothermia and hemorrhage in of resuscitation. It is important to ascertain whether
a pig shock model. 53 This test was more sensitive than PT fluids are required. Traumatized patients do not always
(did not prolong at all) and aPTT (prolonged only in have blood loss. When an intravascular volume deficit is
combined hemorrhage and hypothermia) in detecting confirmed, it is useful to construct a mental algorithm
clotting changes since platelets and other blood clotting when managing patients with hypovolemia. It is best to
components are included in the test. Thromboelas- start with the question, “Is there hemorrhage or not?”
tography is also useful as this test was also altered in all If “yes,” “is the hemorrhage compressible or noncom-
three scenarios, and detects the mechanisms associated pressible?” If it is compressible, the patient should be
with coagulation abnormalities; 53 however, this is a very managed to an optimal goal of resuscitation. If it is non-
expensive test precluding it as a practical trending test in compressible, the patient should be resuscitated to an
the resuscitative setting where frequent measurements are adequate hemodynamic state as described in the section
required. A study monitoring the ACT in human trauma on Endpoints of Fluid Resuscitation. Other questions
patients during resuscitation in the operating room, include “Is there hemorrhage associated with pulmonary
concluded that a low ACT reflects the initial hypercoag- contusions?” If so, the patient should be resuscitated to
ulability associated with major trauma and an elevated adequate perfusion (see Endpoints of Fluid Resuscitation
ACT is an objective indicator that the coagulation system section). “Is surgical intervention required?” If so, the
2
reserve is near exhaustion. As the ACT is prolonged in patient should be resuscitated to an adequate hemody-
brain trauma (brain tissue is a trigger for DIC), this test namic state and then to optimal perfusion when the hem-
cannot be reliably used as an assessment of dilutional orrhage is controlled (see Endpoints of Fluid
coagulopathy where head injury is present. Resuscitation section). “If hemorrhage is not present, is
As a guide for the normal range for ACT, obtained capillary leak present or not? If capillary leak is not pres-
using various techniques, before establishment of the ent, is COP normal or not?” If COP is normal, the patient
normal range for ACT within each individual institution, should be resuscitated to optimal perfusion (see
refer to Table 16-5. Endpoints of Fluid Resuscitation section). Crystalloids
frequently are adequate. If not, a synthetic or natural col-
loid may be required. If capillary leak is present, fluid
Compressible Hemorrhage selection is crucial, and different types of fluids frequently
When hemorrhage is compressible (i.e., that occurring are necessary. Resuscitation to optimal perfusion should
from a limb), pressure is easily applied and hemorrhage be attempted, but resuscitation to adequate perfusion