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To help identify the specific cause, health care providers and the laboratory calculate the anion gap, a reflection of unmeasured anions in plasma. You calculate anion gap by subtracting the sum of plasma concentrations of the anions Cl− and image from the plasma concentrationof the cation Na+. When reviewing laboratory reports, check the referencevalues from the laboratory that measured the electrolyte concentrations (Table 42-8).oMetabolic AlkalosisMetabolic alkalosis occurs from a direct increase of base (image) or a decrease of metabolic acid, which increases blood image by releasing it from its buffering function. Common causes include vomiting and gastric suction (see Table 42-7). The respiratory compensation for metabolic alkalosis is hypoventilation. The decreased rate and depth of respiration allow carbonic acid to increase in the blood, as seen by an increased PaCO2. The need for oxygen may limit the degree of respiratory compensation for metabolic alkalosis. Because image crosses the blood-brain barrier with difficulty, neurological signs and symptoms are less severe or even absent with metabolic alkalosis.oRespiratory AcidosisRespiratory acidosis arises from alveolar hypoventilation; the lungs are unable to excrete enough CO2. The PaCO2 rises, creating an excess of carbonic acid in the blood, which decreases pH (Table 42-7). The kidneys compensate by increasing excretion of metabolic acids in the urine, which increases blood bicarbonate. This compensatory process is slow, often taking 24 hours to show clinical effect and 3 to 5 days to reach steady state. Decreased cerebrospinal fluid (CSF) pH and intracellular pH of brain cells cause decreased level of consciousness.oRespiratory AlkalosisRespiratory alkalosis arises from alveolar hyperventilation; the lungs excrete too much carbonic acid (CO2 and water). The PaCO2 falls, creating a deficit of carbonic acid in the blood, which increases pH (see Table 42-7). Respiratory alkalosis usually is short lived; thus the kidneys do not have time to compensate. When the pH of blood, CSF, and ICF increases acutely, cell membrane excitability also increases, which can cause neurological symptoms such
as excitement, confusion, and paresthesias. If the pH rises high enough, central nervous system (CNS) depression can occur.IV therapy oInsertionAfter you collect the equipment at the patient's bedside, prepare to insert the IV line by assessing the patient for a venipuncture site. The most common IV sites are on the inner arm. Do not use hand veins on older adults or ambulatory patients. IV insertion in a foot vein is common with children, but avoid these sites in adults because of the increased risk of thrombophlebitis.As you assess a patient for potential venipuncture sites, consider conditions that exclude certain sites. Venipuncture is contraindicated in a site that has signs of infection, infiltration, or thrombosis. An infected site is red, tender, swollen, and possibly warm to the touch. Exudate may be present. Do not use an infected site because of the danger of introducing bacteria from the skin surface into the bloodstream. Avoid using an