NUR 101 M. Gardner Copyright2/4/2013

 In order to meet homeostasis, the body fluids must maintain a stable chemical balance of hydrogen ions in body fluids.  This is done by regulating their acidity /alkalinity.  Deviation from a normal value indicates that the client is experiencing an acid/base imbalance

 ACID – substance that releases hydrogen ions (H+)  BASE – accept hydrogen ions in solution  This relationship is measured as pH.

 Measurement of ABGs involves analysis of several components:  pH  PCO2  PO2  HCO3

Arterial blood gas analysis  pH – measures the hydrogen ion concentration  it is an indication of the blood’s acidity or alkalinity.  Normal pH of body fluids is  pH 7 is neutral  pH 7 is alkaline (base) acidic----neutral----alkaline

PaCO2/PCO2  35-45mmHg  Carbon dioxide/CO2  Reflects adequate ventilation by the lungs  Hyperventilation occurs PaCO2 <35mmHg. RR/depth increases the more carbon dioxide is exhaled  Hypoventilation occurs PaCO2>45mmHg.  RR/depth decreases, more carbon dioxide is retained – increasing the concentration of CO2

HCO3 /Bicarbonate  normal range 22-26mE/L  base regulated by the kidneys  the kidneys excrete and retain HCO3 to maintain a normal acid/base balance  is a principal buffer of the ECF compartment  < 22mEq/L – indicates metabolic acidosis  >26meq/L – indicates metabolic alkalosis

 PO2 – oxygen in arterial blood  Normal range – mmHg

 Several body systems are actively involved in maintaining the narrow pH range necessary for optimal function.  This includes  buffers, respiratory system, renal system  Buffers  maintain acid/base balance by neutralizing excess acids/bases  The lungs/kidneys help maintain a normal pH by either excreting/retaining acid/bases.

 A strong acid added to the ECF causes the bicarbonate to become depleted  neutralizing the acid  pH drops  acidosis  A strong base is added to the ECF, depleting carbonic acid  the pH rises  alkalosis  Buffer reaction is immediate

 Lungs regulate acid/base balance by eliminating or retaining carbon dioxide (CO2)  Carbon dioxide  powerful stimulator of the respiratory center  CO2 +H2O=H2CO3  this reaction is reversible

 Kidneys kick in by excreting or retaining bicarbonate and hydrogen ions.  Slower to respond to changes  hour/days to correct imbalances

 Excessive hydrogen ions are present and the pH falls (acidosis)  kidneys reabsorb bicarbonate & excrete hydrogen ions.  With alkalosis and high pH  excess bicarbonate is excreted and hydrogen ions are retained.

pH 7.35 – 7.45 Pa CO mm Hg PaO mm Hg HCO mEq/L O2 Saturation %

 Are classified as respiratory or metabolic  considering the general/underlying cause of the disorder.  Respiratory acidosis/alkalosis  retention/excretion of CO2  Bicarbonate /hydrogen levels are regulated by the kidneys, any problems  metabolic acidosis/alkalosis

 Client hypoventilates  CO2 builds up in the bloodstream and the pH drops below normal.  Kidneys try to compensate by conserving bicarbonate  raises the pH pH <7.35 PaCO2 >45 HCO3 normal or elevated if compensating

Causes:  asthma, COPD  chest wall trauma  sedation medications  Acute lung conditions

Clinical Manifestations  apprehension  dizziness  muscular twitching  warm flushed skin  lethargy  diminished/absent breath sounds over the affected area

Interventions  bronchodilator  chest physiotherapy  suction  T,C, & DB  narcotic antagonist

 Pt. hyperventilating  this causes the lungs to blow off CO2. ABG pH > 7.45 pCO2 <35 HCO3 - normal or below 22, if compensating

Causes Hyperventilation due to  extreme anxiety  pain  inappropriate mechanical ventilator settings  elevated body temperature

Clinical Manifestations  increase in rate & depth of respirations  tachycardia  anxious, restlessness

Interventions  treat the underlying disorder  allay anxiety – prevent hyperventilation  monitor VS  assist client to breathe in a paper bag

 Bicarbonate levels are low in relation to the amount of carbonic acid  pH low. ABG  pH is below 7.35  pCO2 normal, if less than 35 may be compensated  HCO3 -- <22 mEq/L

Causes  starvation  diarrhea  poisoning  diabetes

Clinical Manifestations  headache  lethargy  confusion  tachypnea with deep respirations

Interventions  treat the underlying problem  replace F/E  sodium bicarbonate – IV  monitor neurological status

 Commonly associated with hypokalemia  Increase levels of bicarbonate ABG  pH >7.45  pCO2 normal or above 45 if compensating  HCO3 >26

Cause  Excessive acid loss from the GI tract  Diuretic therapy

Clinical manifestations  Slow, shallow respirations  S&S are commonly associated with an underlying condition

Interventions  monitor VS  maintain patent IV access  monitor I&O  replace F&E

 It is a respiratory problem if the pH and CO2 are traveling in the opposite directions.  pH 45 = Respiratory Acidosis  pH >7.35 & CO2<35 = Respiratory Alkalosis

 It is a metabolic problem if the pH & HCO3 are traveling in the same directions  pH <7.35 and the HCO3 <22 = Metabolic Acidosis  pH >7.45 and the HCO3>26 = Metabolic Alkalosis

 pH – 7.30  pCO2 – 36mmHg  HCO3 – 14mEq/L  pH – 7.52  pCO2 – 47 mmHg  HCO3 – 43 mEq/L

 The patient comes to the ER with complaint of vomiting for 3 days. Which acid base imbalance is she at risk for?  The patient has just returned from surgery. He was medicated twice with narcotic analgesics in the PACU. He is difficult to arouse and has a respiratory rate of 12. what acid/base imbalance is he at risk for?

 Some day you will know all of this!!!!!!!!