Ch 7.2: Acid-Base Disorders Flashcards

Question

Respiratory Acidosis Acute Causes

Answer 1

Acute airway disorders * Airway obstruction * Asthma/COPD *exacerbation* Acute central nervous system depression * Drug overdose * Head trauma * Stroke * Infections Acute neuromuscular disorders * Guillain-Barre * Spinal cord injury * Neuromuscular blocking agents Acute respiratory disorder * Pneumonia * Pulmonary edema * Pulmonary embolus * Hemothorax * Pneumothorax Parenteral or enteral nutrition overfeeding * Excess CHO calories in PN solutions can lead to increased CO2 production and potential difficulty in weaning from respirators ## Footnote In setting of hypoventilation = retaining CO2 (acid)

Answer 2

* Asthma * COPD, emphysema * Obstructive sleep apnea * Hypoventilation syndromes * Diaphragmatic paralysis * Myasthenia gravis * Amyotrophic lateral sclerosis (ALS) * Spinal cord injury * Multiple sclerosis * Muscular dystrophy * Poliomyelitis * Kyphoscoliosis * Hypothyroidism ## Footnote In setting of hypoventilation = retaining CO2 (acid)

Answer 3

Occurs when effective alveolar ventilation is increased beyond the level necessary to eliminate metabolically produced CO2 **Hyperventilation** ## Footnote Disease in which, due to reduced oxygen in blood (hypoxemia), the respiratory center is stimulated can result in respiratory alkalosis.

Answer 4

* Central nervous system disorders (anxiety, pain, infections, head trauma, malignancy, cerebrovascular disease) * Hypoxia, high altitudes * Lung disorder (Pneumonia, pulmonary edema, pulmonary embolism, asthma, hyperventilation, interstitial fibrosis) * Mechanical ventilation * Pregnancy * Sepsis * Medications (Xanthine derivatives, nicotine, catecholamines, salicylates) * Hepatic encephalopathy / cirrhosis ## Footnote In setting of hyperventilation = blowing off CO2 (acid)

Answer 5

= Na – (Cl + HCO3) | Decreased AG = decreased unmeasured anions (e.g., Albumin)

Answer 6

* Hypoalbuminemia * = AG + 2.5 x (4.5 – measured albumin) | For 1g/dL decrease of Alb, 2.5 mEq/L must be added to the anion gap

Answer 7

Used to differentiate the 2 main types of metabolic acidosis * Normal anion gap acidosis (hyperchloremic acidosis) * Elevated anion gap acidosis

Answer 8

* mEq for mEq replacement of extracellular HCO3 by Cl * the anion gap doesn’t change because the sum of major anions remains constant

Answer 9

* GI bicarb losses – diarrhea, pancreatic or SB fistula * Renal bicarb losses – type 2 renal tubular acidosis, hyperparathyroidism, hypoaldosteronism * Ingestion of ammonium chloride or PN containing chloride salts **USEDCAR** * **U**reteroenterostomy (urinary diversion) * **S**mall bowel (pancreatic / biliary) fistula * **E**xcessive chloride salts (IVF / parenteral nutrition) * **D**iarrhea * **C**arbonic anhydrase inhibitors (acetazolamide) / chronic kidney disease * **A**drenal insufficiency / aldosterone deficiency / ammonium chloride * **R**enal tubular acidosis

Answer 10

Accumulation of unmeasured anions → elevation in the anion gap

Answer 11

* Increased production of endogenous acids (lactic acidosis; ketoacidosis - diabetic, starvation, ETOH; inborn errors of metabolism) * Failure to excrete acids (renal failure) * Ingestion of exogenous acid (salicylates, methanol, ethanol) **GOLDMARK** * **G**lycols – ethylene and propylene * **O**xoproline (acetaminophen) * **L**actic acidosis * **D**-lactate acidosis (small bowel bacterial overgrowth) * **M**ethanol * **A**spirin * **R**enal failure * **K**etoacidosis – diabetic and starvation

Answer 12

* Maximum amounts of acetate salts to prevent or correct a hyperchloremic metabolic acidosis * The sodium concentration should be ~normal saline to approximate sodium concentration of the ileostomy fluid

Answer 13

* Characterized by reduced pH, reduced HCO3 * **Compensatory hyperventilation → decreased PCO2 (acid)**

Answer 14

1. Inability of kidneys to excrete dietary H+ load 1. Increase in the generation of H+ – either by addition of H+ or loss of HCO3

Answer 15

**Lactic acidosis** (all cells produce lactic acid if deficient of oxygen; increased lactic acid production and resulting metabolic acidosis occur in any condition in which oxygen delivery to the tissues is severely compromised * Cardiac arrest * Any condition associated with hypovolemic shock (e.g. massive fluid loss) * Liver failure – the liver plays a major role in removing the small amount of lactic acid that is produced during normal cell metabolism, so that lactic acidosis can be a feature of liver failure **Diabetic ketoacidosis** (abnormally high blood concentrations of keto-acids) **Diarrhea** – abnormal loss of bicarbonate from the body **Renal failure** – failure to regenerate bicarbonate and excrete hydrogen ions

Answer 16

Characterized by elevated pH, increased HCO3 * **Compensatory hypoventilation → rise in PCO2**

Answer 17

* Loss of gastric acid (vomiting, NG suction) * Loss of intravascular volume and chloride 2/2 diuretic use * In hospital setting: overzealous treatment of metabolic acidosis with bicarb or an excess of acetate in the PN * Transcellular shift of H+ that occurs with severe hypokalemia

Answer 18

Due to the reciprocal relationship between hydrogen and potassium ions

Answer 19

excreting the excess HCO3 in the urine

Answer 20

is useful in differential diagnosis of metabolic alkalosis and predicts those who will respond to volume repletion

Answer 21

Urine chloride <20 mEq/L Treatment: administration of half-isotonic or isotonic (0.9%) saline * Will not reverse metabolic alkalosis r/t moderate to severe hypokalemia – only KCl administration will correct this disorder Causes: GI loss, vomiting, NG suction, renal loss, diuretics, excessive bicarb administration, rapid correction of hypocapnia

Answer 22

Urine chloride >20 mEq/L High urinary chloride concentration Typically associated with hyperaldosteronism Treatment: management of underlying cause of mineralocorticoid (a class of steroid hormones that regulate salt and water balances) excess * Aggressive potassium repletion with hypokalemia in setting of primary aldosteronism Causes: excess mineralocorticoids, cushing’s syndrome, hyperaldosteronism, profound hypokalemia (<2mEq/L), excessive licorice ingestion (ex: from chewing tobacco)

Answer 23

* High output fistula presenting with respiratory failure * Diabetic ketoacidosis (DKA) presenting with pneumonia