Page 132 - Cote clinical veterinary advisor dogs and cats 4th

44.e4 Alkalosis

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○ Bicarbonate (HCO 3 ): high (by definition) ventilation. Otherwise, resolution or treat- ■ pH is normal with an abnormal PCO 2
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and/or HCO 3 .
in metabolic alkalosis, unless mixed acid- ment of the underlying stimulus for ■ pH changes in a direction opposite to
VetBooks.ir ○ ders) is present hypochloremia, and tion of analgesic or anxiolytic agents, active what is expected for the primary
hyperventilation (e.g., through administra-
base disorder (opposing/offsetting disor-
Hypokalemia,
cooling of the hyperthermic patient).
disorder.
hypocalcemia are possible.
(neutralizing pH abnormalities) may occur
• Abdominal radiographs (or ultrasound) to Chronic Treatment • A respiratory alkalosis with metabolic acidosis
evaluate for gastric outflow obstruction: left Fluid therapy may be required for several days in conditions such as septic shock, gastric
lateral view to diagnose pyloric outflow to correct all deficits. In cases in which the dilation/volvulus (GDV), liver disease, and
obstruction loss of gastric fluid has induced metabolic after cardiopulmonary resuscitation.
alkalosis, gastric acid secretion may be reduced • The development of respiratory alkalosis in
Advanced or Confirmatory Testing by treatment with a proton pump inhibitor an animal with metabolic acidosis may
• Alkalosis may be defined on a routine serum or H2-blocker. If excessive nasogastric suc- indicate the development of septicemia or
biochemistry panel (elevated [TCO 2 ]). tioning was a cause, the measurement and aspiration pneumonia.
• Arterial or venous blood gas analysis is subsequent return of some of the reflux may • Respiratory acidosis may occur together with
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necessary to characterize an alkalosis as limit Cl loss. Treatment of respiratory alkalosis metabolic alkalosis in cases of pulmonary
metabolic or respiratory, and the effects requires correction of the underlying causes of edema treated with diuretics and in cases of
of compensatory changes should also be hyperventilation. GDV.
identified. • Mixed metabolic alkalosis with metabolic
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○ For each 1 mEq/L increase in HCO 3 , Nutrition/Diet acidosis is usually seen in animals with
an increase of 0.7 mm Hg in PCO 2 can Patients with congestive heart failure receiving long-standing high–anion gap acidosis (such
be expected in compensation in dogs and loop diuretics to control pulmonary edema may as with renal failure) that begin vomiting
cats. require oral KCl supplementation to lessen or and develop hypochloremia. Alternatively,
○ Acute respiratory alkalosis results in a prevent metabolic alkalosis. the mixed disturbance may begin as a meta-
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2.5 mEq/L drop in HCO 3 for each bolic alkalosis followed by the development
10 mm Hg drop in PCO 2 in dogs and Possible Complications of severe volume depletion and lactic acidosis.
cats. Chronic respiratory alkalosis results Patients with chronic pulmonary disease and Recognition of this mixture of disorders is
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in a 5.5 mEq/L drop in HCO 3 for each chronic hypercapnia are at greater risk for important because treatment of the one
10 mm Hg drop in PCO 2. metabolic alkalosis than others because super- imbalance allows the other to emerge
• Because respiratory alkalosis is frequently imposition of metabolic alkalosis on the chronic unopposed.
associated with respiratory disease, advanced lung disorder can further reduce ventilation • Respiratory alkalosis may occur together with
investigations should focus on pulmonary and lead to worsened hypoxemia. The clinician metabolic alkalosis and may develop in dogs
disease (including techniques such as thoracic should be cautious about giving oxygen to with chronic respiratory disease that are
imaging, airway endoscopy, and sample animals with metabolic alkalosis because this receiving diuretics. Sudden ventilation of
collection). may reduce alveolar ventilation and aggravate dogs with established respiratory acidosis
hypoxemia. may acutely drop PCO 2 in a dog that has
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TREATMENT established compensatory increased [HCO 3 ],
Recommended Monitoring and this can lead to severe alkalemia.
Treatment Overview Blood gas and serum electrolytes
Prevention
The permanent solution to either respiratory PROGNOSIS & OUTCOME Clinicians should be aware of the conditions
or metabolic alkalosis is resolution of the that may lead to alkalosis and the treatments
precipitating cause (e.g., resolving the cause of Depends on the underlying disease process that may precipitate metabolic alkalosis. The
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vomiting, administering analgesics). timely supplementation of Cl may prevent
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• The goal of treatment in Cl -responsive PEARLS & CONSIDERATIONS this.
metabolic alkalosis is to provide sufficient
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Cl to replace the deficit while supplementing Comments Technician Tips
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K and Na . • Almost all critically ill patients have an Changes in respiratory pattern or mentation
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• Cl -resistant alkalosis requires restoration acid-base abnormality, but few require should prompt investigation of acid-base status
of adequate circulating blood volume and intervention beyond treatment of the inciting in ill patients.
resolution of the underlying disease process cause.
for correction of the acid-base abnormality. • Patients with chronic pulmonary disease that SUGGESTED READING
have hypoxemia and hypercapnia are at risk Ha YS, et al: Incidence, nature, and etiology of
Acute General Treatment for metabolic alkalosis (usually because of metabolic alkalosis in dogs and cats. J Vet Intern
• The IV fluid of choice in the treatment of diuretic use). If metabolic alkalosis develops, Med 27:847-853, 2013.
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patients with Cl -responsive metabolic it can further reduce ventilation and worsen
alkalosis is 0.9% NaCl (normal saline) with hypoxemia. Therefore, metabolic alkalosis ADDITIONAL SUGGESTED
added KCl. It is important to supplement should not be overlooked if the patient has READING
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K because most patients with metabolic a chronic lung disease. Foy DS, et al: A quick reference on metabolic
alkalosis have been sick long enough to be • Chronic respiratory alkalosis may present alkalosis. Vet Clin North Am Small Anim Pract
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K depleted, and a K deficit does not correct with a normal pH because compensation 47:197-200, 2017.
on its own, even if the acid-base balance may be complete. DiBartola SP: Acid-base disorders. In DiBartola SP,
corrects. Saline-induced diuresis may worsen • Animals can have serious acid-base abnor- editor: Fluid therapy in small animal practice, ed
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K deficiency. malities with normal blood pH (mixed 4, Philadelphia, 2012, Elsevier Saunders.
• If hyperventilation is a result of hypoxemia, acid-base disorders). AUTHOR: Kristin Welch, DVM, DACVECC
the administration of supplemental oxygen ○ Mixed disorders should be suspected if EDITOR: Benjamin M. Brainard, VMD, DACVAA,
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may result in increased PCO 2 because ■ PCO 2 and HCO 3 change in opposite DACVECC
the increased PO 2 lessens the drive on directions.
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