Page 547 - Fluid, Electrolyte, and Acid-Base Disorders in Small Animal Practice

Fluid and Diuretic Therapy in Heart Failure 535

inhibitor may reduce serum sodium concentration, clini- variables. It is important to tabulate and establish the
cal experience in this setting is just the opposite. Severe trend of important clinical signs: body temperature,
hyponatremia (<120 mEq/L) requires water restriction respiratory rate and depth (in hospital and at home),
and cautious infusion of 0.9% saline or low-volume hyper- breath sounds, heart rate, heart rhythm, mucous mem-
tonic saline to prevent the neurologic consequences of brane color and refill time, pulse strength, attitude, and
hyponatremia (see Chapter 3). Mannitol or low-volume noninvasively determined arterial blood pressure
hypertonic saline may increase delivery of filtrate to (Box 21-7). Frequent determination of such simple
the distal diluting segments of the nephron and may variables as water and food intake, estimated urine out-
increase free-water clearance. With few exceptions, put, body weight, and diuretic dosage provides the clini-
patients with CHF and severe hyponatremia are unre- cian with useful information about fluid dynamics and the
sponsive to therapy. Therapy with ADH (vasopressin) need for fluid therapy. Home respiratory rates exceeding
receptor antagonists that block the effects of ADH on 35 to 40 in resting dogs correlates well with radiographic
the distal nephron are available for human use and may evidence of pulmonary edema. Serial determination of
be a consideration. These antagonists have been effective serum creatinine, BUN, sodium, and potassium
in treatment of experimental canine CHF. 108,150,184 concentrations is useful for monitoring fluid, diuretic,
and cardiac therapy. Physical and radiographic signs of
MONITORING OF PATIENTS fluid accumulation may indicate a need to reduce fluid
volume in hospitalized patients and to increase diuretic
Cardiac patients require careful monitoring of clinical, dosage or to consider additional treatments. For critically
hematologic, cardiac, radiographic, and hemodynamic ill dogs, more accurate hemodynamic information can be

BOX 21-7 Evaluation of the Cardiac Patient

Inspection and Examination Echocardiography and Doppler Studies
Body weight Morphologic diagnosis
Estimated hydration Ventricular systolic function (ejection fraction)
Jugular venous pressure Ventricular diastolic function (Doppler studies)
Arterial blood pressure (indirect or direct) Estimation of right atrial and ventricular filling (preload)
Body temperature Hemodynamic estimates of left atrial and venous filling
Pulse rate and quality pressures (Doppler studies)
Respiratory rate Determination or Calculation of:
Pattern of ventilation Intravenous fluid requirements
Cardiac auscultation Oral water intake
Pulmonary auscultation and percussion Urinary output
Level of consciousness Total daily sodium intake (intravenous and dietary)
Muscle strength Total daily potassium intake (intravenous and dietary)
Mucous membrane color and capillary refill time Total daily caloric intake
Evaluation for ascites (measurement of girth)
Environmental temperature and humidity
Laboratory Evaluation Hemodynamic Measurements
Blood urea nitrogen and serum creatinine
Central venous pressure (right-sided filling pressures)
Serum electrolytes (sodium, potassium, chloride)
Pulmonary capillary wedge pressure (left-sided filling
Blood gas tensions (PO 2 ,PCO 2 )
pressures)
Blood pH and bicarbonate
Cardiac output
Chest Radiograph Pulmonary vascular resistance
Evaluation of heart size Systemic vascular resistance (if arterial line in place)
Pulmonary vascularity Current Therapy
Pulmonary infiltrates or edema
Diuretic drugs
Pleural effusion
Crystalloid and additives
Electrocardiogram Cardiotonic agents, including digitalis
Vasodilators and angiotensin-converting enzyme inhibitors
Heart rate and rhythm
ST segment (myocardial perfusion or ischemia) Additional measures: paracentesis, oxygen, antiarrhythmic
Twave drugs, bronchodilator, omega-3 fatty acids