Honan: Chapter 4: Acid-Base Disturbances.

Bicarbonate to Carbonic acid: (HCO3- to H2CO3)

Main chemical buffer; 20:1 ratio; when the ratio is altered, the pH changes

PaCO2

35-45 mmHg

Plasma pH

7.35-7.45

HCO3-

Bicarbonate

Mechanisms of pH

Buffer systems, Kidneys, and the Lungs

Role of kidneys in acid-base balance

Control bicarbonate Regulates hydrogen ion secretion and bicarbonate reabsorption. If kidneys retain bicarbonate- level of base increases If kidneys excrete excess bicarbonate- level of base decreases

Sources for HCO3-

Intestinal lumen, pancreas, kidney, and diet (lesser extent)

metabolic alkalosis

Respiratory rate decreases, causing CO2 to be retained (to increase the acid load)

metabolic acidosis

Respiratory rate increases - causing greater elimination of CO2 (to reduce the acid load)

respiratory acidosis

The kidneys respond to the increased CO2 and decreased pH by excreting hydrogen ions and conserving bicarbonate ions to help restore balance

respiratory alkalosis

The kidneys response to the decreased CO2 and increased pH is to retain hydrogen ions and excrete bicarbonate ions to help restore balance.

alkalemia

abnormal alkalinity of the blood; pH > 7.45

Extracellular buffer system

bicarbonate-carbonic acid buffer system

Which intervention is most appropriate for a client with an arterial blood gas (ABG) of pH 7.5, a partial pressure of arterial carbon dioxide (PaCO2) of 26 mm Hg, oxygen (O2) saturation of 96%, bicarbonate (HCO3-) of 24 mEq/L, and a PaO2 of 94 mm Hg? a. Administer ordered supplemental oxygen b. Administer an ordered decongestant c. Instruct the client to breathe into a paper bag d. offer the client fluids frequently

c. Instruct the client to breathe into a paper bag Reason: The ABG results reveal respiratory alkalosis. The best intervention to raise the PaCO2 level would be to have the client breathe into a paper bag. Administering a decongestant, offering fluids frequently, and administering supplemental oxygen wouldn't raise the lowered PaCO2 level.

The nurse is caring for a patient with diabetes type I who is having severe vomiting and diarrhea. What condition that exhibits blood values with a low pH and a low plasma bicarbonate concentration should the nurse assess for? a. Respiratory acidosis b. Respiratory alkalosis c. Metabolic alkalosis d. Metabolic acidosis

d. Metabolic acidosis Reason:Metabolic acidosis is a common clinical disturbance characterized by a low pH (increased H+ concentration) and a low plasma bicarbonate concentration. Metabolic alkalosis is a clinical disturbance characterized by a high pH (decreased H+ concentration) and a high plasma bicarbonate concentration. Respiratory acidosis is a clinical disorder in which the pH is less than 7.35 and the PaCO2 is greater than 42 mm Hg and a compensatory increase in the plasma HCO3 occurs. Respiratory alkalosis is a clinical condition in which the arterial pH is greater than 7.45 and the PaCO2 is less than 38 mm Hg.

Acidemia

elevated acidity of blood (pH < 7.35)

Less important buffer system in ECF

inorganic phosphates and Plasma proteins

ICF Buffer System

proteins, organic and inorganic phosphates, and hemoglobin

Carbon Dioxide (CO2)

regulated by lungs, when dissolved in water become Carbonic acid (CO2+H2O=H2CO3)

bicarbonate-carbonic acid buffer system

regulates plasma pH by adding hydrogen ions to increase acidity and removing them to promote alkalinity