Acid Base Balance Marion Technical College NUR 1021 Spring 2016

I. ACID BASE DISORDERS A. Hydrogen ions determine acidity of body fluids B. Acids release hydrogen ions in solution ◦ 1. If hydrogen ions increase, pH falls & results in acidity C. Bases accept hydrogen ions ◦ 1. If hydrogen ions fall solution is more alkaline D. Hydrogen ion concentration is noted by pH E. Normal pH is slightly basic ◦

A. BUFFER SYSTEMS 1. Buffers bind with H+ to minimize change in pH 2. Bicarbonate-Carbonic Acid Buffer ◦ a. Ratio of bicarbonate to carbonic acid is 20 :1 in order to maintain the pH of the blood ◦ b. Normal serum bicarbonate (base) is 24mEq/L & carbonic acid is 1.2mEq/L

The normal ratio of bicarbonate to carbonic acid is 20:1. As long as this ratio is maintained, the pH remains within the normal range of 7.35 to 7.45.

3. RESPIRATORY SYSTEM Buffer ◦ a. Regulates carbonic acid by eliminating or retaining carbon dioxide ◦ b. Carbon dioxide is a potential acid & forms carbonic acid when combined with water ◦ c. The accumulation of CO² and H+ stimulate respiratory center to increase respirations ◦ d. This eliminates carbonic acid from the body & brings pH back to normal

4. RENAL SYSTEM buffer ◦ a. Responsible for long term regulation of acid-base balance ◦ b. Kidneys respond more slowly (hours to days) ◦ c. Kidneys will excrete H+ and retain bicarbonate ions in acidosis ◦ d. In alkalosis, kidney will retain H+ and excrete bicarbonate ions

B. Assessment of ACID-BASE 1. Normally by blood gases 2. PaCO² is the respiratory component of acid-base regulation ◦ a. Normal: mmHg 3. Serum bicarbonate (HCO³-) reflects renal regulation of acid-base ◦ a. Normal: 22-26mEq/L 4. Base excess represents amt of acid or base that must be added to blood sample to achieve a normal pH ◦ a. Measure of increased or decreased HCO³-

C. COMPENSATION 1. Compensatory changes in respirations occur within minutes of a change in pH 2. Renal response takes longer but is a more effective long term mechanism 3. If pH restored to normal- fully compensated 4. Partially compensated – changes in other values occur but pH is outside normal limits

D. Metabolic Acidosis 1. Is a bicarbonate deficit ◦ a. Low pH & low bicarbonate, increased H+ ◦ b. Respiratory system responds by increasing rate & depth to eliminate carbon dioxide 2. Metabolic acidosis is not a primary disorder but develops during course of a disease ◦ a. DKA ◦ b. Acute lactic acidosis – shock or cardiac arrest ◦ c. CRF- Increases H+ in body fluids ◦ d. Intestinal suction or abdominal fistulas

Metabolic acidosis - pH decreased & HCO³ decreased

3. Manifestations ◦ a. Weakness, fatigue, h/a, general malaise ◦ b. Anorexia, n/v, abd pain ◦ c. LOC decreases to stupor & coma ◦ d. Cardiac dysrhytmias –cardiac arrest ◦ e. Skin – warm & flushed ◦ f. Kussmaul’s respirations ◦ g. Potassium- elevated as it’s retained as kidney excrete’s H+

4. Treatment ◦ a. Alkalanizing solution as bicarbonate to reduce effects of acidosis on cardiac function ◦ b. ACUTE- IV, CHRONIC- Oral ◦ c. Monitor client carefully with IV bicarbonate as it can rapidly correct & lead to metabolic alkalosis ◦ d. Rx for DKA is IV insulin & fluid replacement

Think Like a Nurse! A diabetic patient who has not been following his established meal plan did not eat lunch today. What is an expected outcome for this patient? A.Metabolic acidosis B.Metabolic alkalosis C.Respiratory acidosis D.Respiratory alkalosis

E. Metabolic ALKALOSIS 1. Is a bicarbonate excess>26 mEq/L 2. pH > Caused by excess loss of acid or excess of bicarbonate in the body 4. Respiratory rate slows & carbon dioxide retained and PaCO² increases 5. H+ lost through kidneys from hypokalemia or GI secretions 6. Excess antacids as Alka-Seltzer

7. MANIFESTATIONS ◦ a. Confusion, decrease LOC ◦ b. Hyperreflexia ◦ c. Tetany ◦ d. Dysrhytmias ◦ e. Seizures ◦ f. Respiratory failure

8. Treatment ◦ a. Restore normal fluid volume ◦ b. Adm potassium chloride & sodium chloride solutions  1. K+ restores serum levels and allows kidneys to conserve H+  2. Cl- promotes excretion of bicarbonate

Metabolic Alkalosis – pH elevated and HCO³ elevated

F. RESPIRATORY ACIDOSIS 1. Caused by excess of dissolved carbon dioxide 2. pH 45 mmHg 3. Any condition that interferes with ventilation as narcotics or obstructive disease can cause this ◦ a. Hypoxemia (low oxygen) often accompanies respiratory acidosis

4. Hypercapnia will dilate cerebral vessels & cause increased intracranial pressure 5. Chronic respiratory acidosis ◦ A. Retain bicarbonate & pH remains close to normal; PaCO² increases over time

6. MANIFESTATIONS ◦ a. Neuro: Drowsy, disoriented, h/a, dizzy, coma ◦ b. Cardio: Low BP, ventric fib, warm flushed skin ◦ c. Neuromuscular: Seizures ◦ d. Respiratory: Hypoventilation & hypoxia 7. Treatment ◦ a. Bronchodilater drugs, pulmonary hygiene ◦ b. Respiratory support- ventilator

Respiratory acidosis: ph decreased and PCO² elevated Respiratory acidosis: ph decreased and PCO² elevated

G. RESPIRATORY ALKALOSIS 1. Result from conditions that cause overstimulation of respiratory system ◦ a. Hyperventilation that leads to carbon dioxide deficit 2. pH >7.45, PaCO² <35mmHg 3. Kidneys are not able to adapt rapidly to change in pH that rises rapidly as carbon dioxide falls

4. Causes ◦ a. Anxiety based hyperventilation ◦ b. High fever ◦ c. Overventilation by mechanical ventilators 5. Manifestations ◦ a. Lightheadedness, feeling of panic ◦ b. Circumoral & distal extremity paresthesias ◦ c. Tremors, + Chvostek’s & Trousseau’s ◦ d. Chest tightness, palpitations ◦ e. Seizures & loss of consciousness

6. Treatment ◦ a. Sedative or antianxiety agent ◦ b. Instruct to breathe more slowly & use a paper bag or rebreather mask  1. Allows rebreathing of carbon dioxide and increases the levels and reduces the pH ◦ c. Adjust ventilator settings if indicated to reduce respiratory rate

Think Like a Nurse! The patient has experienced several fractured ribs after being involved in an automobile accident. She is receiving pain medication frequently. What is an expected outcome for this patient? A.Metabolic acidosis B.Metabolic alkalosis C.Respiratory acidosis D.Respiratory alkalosis

Respiratory alkalosis- pH increased & PCO² decreased

H. SUMMARY 1. Metabolic acid-base imbalances ◦ a. Remember, the metabolic function indicator is the bicarbonate ion (HCO³-) ◦ b. In a metabolic imbalance, pH will be elevated and the HCO³- will be elevated (alkalosis), or the pH will be decreased and the HCO³- will be decreased (acidosis) ◦ c. Look at the pH & HCO³- to determine whether the condition is a metabolic problem

2. Respiratory Acid-Base Imbalances ◦ a. Remember the respiratory function indicator is the PCO² ◦ b. In respiratory imbalance, the pH will be elevated with a decreased CO²(alkalosis) or the pH will be decreased with an elevated PCO²(acidosis) ◦ c. Look at the pH and PCO² to determine whether the condition is a respiratory problem

Think Like a Nurse! The nurse working in the ER admits a patient with renal failure and a serum potassium level of 8.0 mEq/L. All these orders are received from the health care provider. Which order will the nurse implement first? A. Place the patient on a cardiac monitor B. Insert a foley catheter C. Administer Kayexalate 15 g. orally D. Give IV furosemide (Lasix) 40 mg