Page 47 - Critical Care Nursing Demystified

32 CRITICAL CARE NURSING DeMYSTIFIED

Conditions That Abnormal Arterial Blood Gases Show Us

Respiratory acidosis – pH less than 7.35, pCO greater than 45 mm Hg.
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Causes – Central nervous system (CNS) depression of high spinal cord
injury, head trauma, anesthesia, and oversedation. Further examples
include pneumothorax, hyperventilation, bronchial obstruction, atelecta-
sis, pulmonary infections, heart failure, pulmonary edema, pulmonary
embolus, exacerbation of myasthenia gravis, and multiple sclerosis.
Signs and symptoms – Dyspnea, restlessness, headache, tachycardia, con-
fusion, lethargy, drowsiness, dysrhythmias, respiratory distress, and de-
creased responsiveness.
Respiratory alkalosis – pH greater than 7.45, pCO less than 35 mm Hg.
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Causes – Fear, anxiety, pain, fever, hyperventilation, thyrotoxicosis, CNS
lesions, salicylates, pregnancy, gram-negative septicemia.
Signs and symptoms – Confusion, lightheadedness, impaired concentra-
tion, paresthesias, tetany spasms in arms and legs, palpitations, dysrhyth-
mias, dry mouth, blurred vision, and diaphoresis.
Metabolic acidosis – pH less than 7.35, HCO less than 22 mEq/L. Downloaded by [ Faculty of Nursing, Chiangmai University 5.62.158.117] at [07/18/16]. Copyright © McGraw-Hill Global Education Holdings, LLC. Not to be redistributed or modified in any way without permission.
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Causes – Increased acids from renal failure, ketoacidosis, anaerobic
metabolism, starvation, and salicylate intoxication. Loss of base from diar-
rhea and intestinal fistulas.
Signs and symptoms – Headache confusion, restlessness, lethargy, weak-
ness, stupor, coma, Kussmaul’s respirations, nausea, vomiting, dysrhyth-
mias, warm flushed skin, increased respiratory rate, and depth.

Metabolic alkalosis – pH greater than 7.45, bicarbonate greater than
26 mEq/L.

Causes – Base gain—excessive use of bicarbonates, dialysis, lactate admin-
istration, and excessive ingestion of antacids. Loss of acids—vomiting,
nasogastric suctioning, hypokalemia, hypochloremia, diuretics, and increased
levels of aldosterone.
Signs and symptoms – Tetany, muscle twitching, cramps, dizziness, leth-
argy, weakness, disorientation, convulsions, coma, nausea, vomiting, and
depressed rate and depth of respirations.

Compensation for Abnormalities of Acidemia or Alkalemia
The body attempts to compensate for abnormalities associated with acidemia
or alkalemia. The respiratory or renal systems will attempt to compensate if the
buffer systems cannot maintain a normal pH. If the problem is respiratory in