Page 458 - Clinical Small Animal Internal Medicine

426 Section 5 Critical Care Medicine

surgical exploration. While identification of even one the multifactorial nature of the development of shock in
VetBooks.ir intracellular bacterium confirms the diagnosis of sep- the septic patient, meaning that in any one patient, low
systemic vascular resistance, cardiac dysfunction, and
tic peritonitis, the absence of this finding does not rule
out sepsis. If the fluid obtained is highly cellular (com-
to failure of oxygen delivery (i.e., shock).
posed of mixed inflammatory cells) or is turbid, floc- hypovolemia may all be coexistent and may all contribute
culent or malodorous then further investigation may
be needed. Resuscitation
Comparison of the biochemical values, specifically lac-
tate and glucose, of abdominal fluid with blood can be Complicating septic shock resuscitation is the fact that
invaluable for aiding in the diagnosis of septic peritoni- vascular permeability may be increased, which can
tis. The comparison of glucose and lactate concentra- decrease the efficacy of crystalloid resuscitation or lead to
tions of abdominal fluid and blood is both sensitive and overresuscitation and subsequent edema formation. The
specific for differentiating septic peritonitis from other use of goal‐directed therapy, consideration of other fluids
causes of peritoneal effusion. Under normal conditions, options, and use of vasoactive agents as well as fastidious
the concentration of glucose and lactate in peritoneal reevaluation can improve the efficacy of resuscitation.
fluid is essentially the same as that of blood. As infection The most important initial therapy in the resuscitation
progresses within the peritoneal cavity, bacteria and of a patient with septic shock is the administration of
white blood cells utilize glucose for energy and produce appropriate doses of IV fluids to restore effective circula-
lactate as a by‐product. If the lactate concentration of tory volume and improve global perfusion. The appro-
abdominal fluid is 2.0 mmol/L higher than that of the priate amount and character of the fluids that should be
blood or if glucose is 20 mg/dL lower in the effusion than administered are a matter of debate. The author prefers
in the blood, a presumptive diagnosis of septic peritoni- to give an initial bolus of 20–30 mL/kg of crystalloid flu-
tis can be made and surgical exploration should be ids such as lactated Ringer’s solution or 0.9% sodium
recommended. chloride. This initial dose serves to act as a fluid chal-
Monitoring coagulation assists with identification of lenge and will help the clinician determine if continued
needed therapies rather than identification of sepsis or fluid resuscitation may be beneficial. If a positive
septic shock and coagulation assays may be normal or response is seen, this dose can be repeated 2–3 more
abnormal in these patients. A prothrombin time (PT) or times until one of three endpoints occurs: signs of shock
partial thromboplastin time (aPTT) that is >50% pro- resolve, there is no further improvement in perfusion
longed indicates coagulopathy. Fibrinogen levels may be parameters or volume overload becomes evident. Signs
normal, low or high, depending on the chronicity of the of volume overload include development of peripheral or
disease. Patients that have a prolonged disease course pulmonary edema or measurement of central venous
tend to have higher fibrinogen levels, but it is not uncom- pressures greater than 10 cmH 2 O.
mon to find low fibrinogen due to active consumption. Colloidal solutions are commonly used as a primary or
D‐dimers are often elevated as a result of the underlying secondary resuscitative fluid in veterinary patients in
condition or inappropriate coagulation (i.e., DIC). shock. Colloids have several theoretical benefits, but one
Identification of three of the following in a patient identi- of the most important is that they discourage formation of
fies DIC: prolongation of PT or aPTT, hypofibrinogene- tissue edema since they do not move out of the vascular
mia, thrombocytopenia, elevation of fibrin degradation compartment as quickly as crystalloid fluids. If colloids
products (FDPs) or D‐dimers, or documented antithrom- are used, total doses of 20 mL/kg are typically broken into
bin deficiency. aliquots similar to the technique used with crystalloids
and are administered in incremental 5–10 mL/kg boluses
until endpoints are achieved. Hetastarch (Hespan®,
Treatment Hextend™) is the most commonly used colloid in veteri-
nary patients and has replaced the dextran solutions that
Treatment of sepsis and septic shock must be aggressive were in use previously. A newer generation of hydroxy-
and aimed at eliminating the underlying cause. In broad ethylstarchs, generally classified as tetrastarchs, is also
terms, treatment of sepsis and septic shock can be divided available with a similar dosing schedule.
into several distinct components: resuscitation, source Patients in septic shock, by definition, have hypoten-
control (eliminating the cause of sepsis), antimicrobial sion that is not responsive to fluid loading alone, mean-
therapy, and supportive care. The resuscitation of a ing that vascular expansion has been completed without
patient with severe sepsis or septic shock is different from resulting in resolution of shock. Determining when
that of patients with other forms of shock. This is due to patients are adequately volume expanded is difficult.