Page 590 - Fluid, Electrolyte, and Acid-Base Disorders in Small Animal Practice

Shock Syndromes 577

total protein and the acute history is classic for the syn­
drome known as hemorrhage gastroenteritis. This diag­ Measured Reference
Parameter Value Range
nosis is further supported by the finding of the bloody
diarrhea on rectal examination. This disease process is
pH 7.331 7.34-7.38
characterized by rapid increase in vascular permeability PvCO 2 mm Hg 31.7 40-46
of the gastrointestinal capillaries, leading to massive PvO 2 mm Hg 53.3 49-67
plasma water and protein loss into the lumen of the HCO 3 mEq/L 16.3 22-24
gastrointestinal tract. Despite its name there is minimal SBE mEq/L 8.5 2to0
red blood cell loss leading to an elevation of the Glucose mg/dL 117 65-112
PCV; splenic contraction may further contribute to this Lactate mmol/L 9.1 <2.5
increase in PCV. The consequence is hypovolemic Packed cell volume % 51 37-55
Total protein g/dL 6.5 5.4-7.1
shock and hemoconcentration in combination with
hypoproteinemia due to the protein loss in the gastroin­
testinal tract. A lactic acidosis with appropriate respiratory compen­
This patient requires aggressive blood volume sup­ sation is evident. An electrocardiogram reveals atrial
port. Isotonic crystalloid administration will aid in restor­ fibrillation with a ventricular rate of 170 bpm. Numerous
ing normal blood volume but will further dilute the ventricular premature contractions were also evident.
plasma protein concentration and the low COP will favor Arterial blood pressure is measured with an oscillometric
fluid loss to the interstitium. The addition of an artificial device; systolic pressure is 90 mm Hg, mean pressure is
colloid such as hetastarch will increase COP, helping to 64 mm Hg, and diastolic pressure is 45 mm Hg.
maintain an adequate intravascular volume. This disease A diagnosis of cardiogenic shock secondary to dilated
is not coagulopathic in nature and hence there is no cardiomyopathy is made and a dobutamine constant rate
indication for plasma therapy. Some infectious diseases infusion is started at an initial dose of 4 mg/kg/min. Ten
of the gastrointestinal tract can mimic hemorrhagic minutes later there is little improvement in the perfusion
gastroenteritis and fecal culture is recommended. parameters so the infusion rate is increased to 6 mg/kg/
Atypical hypoadrenocorticism can also present in this min. Over the next 30 minutes the dobutamine infusion
manner and should be considered. In many patients, rate is titrated up to a dose of 12 mg/kg/min at which
the disease appears to be idiopathic and responds to time there is obvious improvement in the dogs perfusion
resuscitation and general supportive care measures. parameters. A blood pressure measurement is repeated at
this time and the systolic pressure is now 104 mm Hg,
mean pressure is 75 mm Hg, and diastolic pressure is
CASE 2: Cardiogenic Shock
50 mm Hg. The dog is sitting up, mucous membrane
An 8-year-old female spayed Doberman pinscher color is pale pink, capillary refill time is approximately
weighing 36 kg is presented collapsed. She has a history 2 seconds, the heart rate is still 170 bpm, femoral pulse
of dilated cardiomyopathy and atrial fibrillation. Her quality has improved, and body temperature is

current medications include furosemide, enalapril, now 99.9 F.
pimobendan, and diltiazem. On presentation the dog is
obtunded, mucous membranes are pale, the capillary CASE 2 - Case Notes
refill time is 2 to 3 seconds, the heart rate is 170 bpm, This dog was in circulatory shock on presentation and the
femoral pulse quality is decreased, and the extremity physical examination findings were consistent with a
temperature feels cool. Auscultation reveals a 2/6 left- vasoconstrictive form of shock. Given the signalment
sided systolic murmur and an irregular heart rhythm, and history of dilated cardiomyopathy, evaluation of car­
the respiratory rate is 50 breaths/min, and no crackles diac function is warranted in this case before considering
or wheezes are heard. Prominent jugular veins are evident fluid administration. The jugular vein distention is consis­
and skin turgor/tent appears normal. The rectal tent with cardiogenic shock and suggests fluid therapy

temperature is 97.1 F. may not be needed at this time. The lactic acidosis is a
On presentation, flow by oxygen is provided and a consequence of poor tissue perfusion. A normal arterial
cephalic venous catheter is placed. A brief echocardio­ blood pressure does not rule out the presence of shock
gram reveals biventricular enlargement with poor systolic and is consistent with compensation achieved by
function. Blood work collected at this time shows the increased systemic vascular resistance. In this case sce­
following: nario, the primary cause of shock is inadequate cardiac