ACID – BASE VETSCAN i-STAT® UTILIZATION GUIDE

B E T T E R . A C T U A L LY.

Acid – Base VetScan i-STAT®

Utilization Guide

Acid-Base Analysis Is Vital to Your Diagnostic Protocols

Chemical reactions, especially those occurring in vivo, are dependent on many factors, none more important than optimal pH. Illness, whether acute or chronic, often results in pH abnormalities. Failure to recognize and address these abnormalities may result in:

• Missed diagnoses• Inappropriate treatment• Delayed or poor patient response to therapy• Increased time in hospital • Frequent relapse • Inability to thrive • Patient death

Acid-Base Definitions

• pH: Measurement of the H+ ion concentration in the plasma • pCO2: Partial pressure of the CO2 in the blood; reflects the amount of carbonic acid present • HCO3

-: The amount of the major buffer (bicarbonate) in the blood • Anion Gap: The amount of unmeasured anions in the blood (Na+ + K+)-(Cl- + HCO3

-). Can be helpful in describing the cause of acidosis • Base Excess: The amount of base needed to return the pH to 7.40. Can be helpful in determining the amount of HCO3

- to administer to the acidotic patient • Electrolytes: Na+, K+ Cl-, Ca2+

• TCO2: Total carbon dioxide, the sum of HCO3- and dissolved CO2 (from pCO2)

Common Presentations of Acid-Base Disorders

Patients you see every day present with clinical signs and/or physical examination findings that may initially suggest a conservative treatment approach. When completely investigated, many of these patients have underlying acid-base abnormalities best treated by a more aggressive approach. This includes both acute and chronic conditions.

Examples: Vomiting, GI Obstruction, GDV, PancreatitisEvaluate acid-base and electrolytes as vomiting causes:• Loss of H+ and Cl- (in the form of HCl)• H+ Loss pH Metabolic Alkalosis• Loss of H+ and Cl- can results in hypochloremic alkalosis• Severe disease causes elevated base excess

Examples: Diarrhea, Viral or Bacterial Infections, Severe Parasitism, Calf Scours, Equine Colic Evaluate acid-base and electrolytes as diarrhea causes:• Loss of HCO3

-

• HCO3- Loss pH Metabolic Acidosis

• Anion gap often normal• Base excess may be decreased

Upper Gastrointestinal

Lower Gastrointestinal

Inability to utilize glucose leads to formation of ketones • Ketones pH Metabolic Acidosis• May see high or normal anion gap depending on severity• Base excess may be decreased

Examples: Heart/Lung Disease, Pneumonia, Chylo/hemo/pyothorax, Neoplasia, Pulmonary/Pleural Effusion Reduced ability to uptake O2 leads to alkalosis• Decreased O2 Hyperventilation pCO2 pH Respiratory Alkalosis• Therapy directed at improving O2 exchange and reducing alkalosis• Long-term monitoring to include acid-base analysis (3–5 days for kidneys to compensate)

Examples: Acute/Chronic Insufficiency/Failure, Urinary ObstructionThe kidney plays a major role in regulation of electrolytes and H+ blood levels• Retention of uremic toxins contributes to increased acid levels• Renal disease leads to acidosis through: Electrolyte abnormalities Buildup of toxins HCO3

- loss and/or H+ retention• Therapy directed at correcting electrolytes and acid-base disorders• Acidosis commonly recurs due to reduced renal function

The American Association of Feline Practitioners recommends routine monitoring and correction of acid-base disorders in chronic renal patients 1

• Addison’s disease• Toxicities: ethylene glycol, lily, acetaminophen• Large Animal: Grain overload Uroperitoneum Neonatal monitoring Field lactate monitoring

Diabetes Mellitus

Cardiothoracic

Renal Disease

Other Common Presentations

Causing Acid-Base Derangement:

1 Pittari J, Rodan I, Beekman G, et al. American Association of Feline Practitioners. Senior care guidelines. J Feline Med Surg. 2009;11:763-778.

Acid-Base Diagnostic Chart

Acidemia Normal Alkalemia

(Low HC03- and high pCO2)

Mixed Acidosis

pCO2 High

HCO3-

Normal

Respiratory Acidosis

HCO3-

Low

pCO2 Normal

Metabolic Acidosis

(High HC03- and

low pCO2)

Mixed Alkalosis

HCO3-

High

pCO2 Normal

Metabolic Alkalosis

pCO2 Low

HCO3-

Normal

Respiratory Alkalosis

pH

HCO3-

Low

pCO2 Low

Compensated Metabolic Acidosis

HCO3-

High

pCO2 High

Compensated Metabolic Alkalosis

Renal Failure Lactic Acidosis Ketoacidosis

Ethyene Glycol Toxicity

Pulmonary Disease Hypoventilation

Anesthesia/Narcotic

Early Renal Disease Diarrhea

Medications

Chronic Vomiting GI Obstruction

Hyperventilation Severe Anemia

Congestive Heart Failure Pneumonia

Pain/Anxiety

Anion Gap

High

Organic Acid Accumulation

Normal

HCO3-

Loss

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CG4+

Hematocrit (Hct)

Hemoglobin (Hgb)

Blood Urea Nitrogen (BUN)

Creatinine

Ionized Calcium (iCa)

Glucose (Glu)

Chloride (Cl)*

Sodium (Na)

Potassium (K)

pH

HCO3

TCO2

Anion Gap

Base Excess

PCO2

PO2

Lactate

ACT Celite

Cardiac Troponin I (cTnl)

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VetScan i-STAT® 1 Cartridge Test Menu

* Chloride on E3+ cartridge available only on the VetScan i-STAT 1 analyzer.

† CHEM8+ and Cardiac Troponin I cartridges available only on the VetScan i-STAT 1 analyzer.