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2. Acid –base Balance
• Arterial blood gases ( ABGs) are most commonly used to assess and treat
acid-base imbalances . The PH of plasma indicates balance or impending
acidosis or alkalosis.
• The partial pressure ( indicated by ‘p’) of these gases .which reflects the
chemical and physical activities of two gases .
• The partial pressure of carbon dioxide PaCO2; For oxygen PaO2 The “a”
indicates an arterial specimen .
• When the PaO2 is low ,hemoglobin carries less than normal amount of
oxygen , when the PaO2 is high ,the hemoglobin carries more oxygen .
• Oxygen saturation readings ( SaO2) reveal the percentage of oxygen in the
blood that combines with hemoglobin.

3. Cont
• The PaCO2 is influenced almost entirely by respiratory activity.
• When PaCO2 is low carbonic acid leaves the body in excessive
amount ; when there the PaCO2 is high , there are excessive amounts
of carbonic acid in the body.
• Acid –base imbalance occurs when the carbonic or bicarbonate levels
become disproportionate .
• When there is a single primary cause ,these disturbances are known
as respiratory acidosis or alkalosis or metabolic acidosis or alkalosis.

4. Acid –base disturbances ?
• Respiratory disturbances alters carbonic acid portion :
• Respiratory acidosis and alkalosis are the results of respiratory
disturbances
• Compensation occurs to resolve balance in the kidneys by either
conserving or excreting more bicarbonate .
• Metabolic disturbance alters the bicarbonate portion:
• Metabolic acidosis and alkalosis are almost entirely the result of
metabolic processes.
• The primary organs for compensation to restore balance are lungs
,which either try to conserve or excrete more CO2 which is available in

7. Respiratory Acidosis ( Carbonic Acid Excess
• Respiratory acidosis is primary excess of carbonic acid in ECF. Any
decrease in a alveolar ventilations that result in retention of C02 can
cause respiratory acidosis.
• As the carbonic acid content increases ,the kidney attempts to retain
more bicarbonate and increase their hydrogen excretion.
• It is clinical state of altered hydrogen excretion. It is clinical state of
altered hydrogen ion concentration, characterized by hypoventilation.
( RA = high PaCO2 because of alveolar hypoventilations )

8. Factors of respiratory acidosis
• Acute respiratory acidosis :acute pulmonary edema ,aspiration of
foreign body , atelectasis.
• Pneumothorax , hemothorex,
• Overdose of sedative or anesthesia
• Cardiac arrest, sever pneumonia, laryngospasm, emphysema
• Bronchiectasis, bronchial asthma ,chronic acidosis
• Obesity
• Abdominal distention from cirrhosis or bowel obstruction

9. Characteristics of acute respiratory acidosis
• Mental cloudiness: ventricular fibrillation may be first sign in anesthetized
patient
• Dizziness:
• Palpitations ( related to hypokalemia )
• Muscular twitching : arterial blood gases ( ABGs)
• Convulsions ( PH below 7.35)
• Warmed flushed skin ( PaCO2 over 45 mm Hg (primary)
• Unconsciousness : HCO3 normal or only slightly elevated

11. CHRONIC RESPIRATORY ACIDOSIS
• ABG s – Ph below 7.35 or within lower limits of normal
• PaCO2 over 4.5 mm Hg ( primary )
• HCO3 – over 26 mEq/ L ( COMENSATORY )
• Treatment : Administer respiratory stimulants i.e is Nikethamide 2-4 ml
of 25% solution by IV repeated every one to two hours and treating the
underline cause

12. Nursing intervention
• Improve ventilation
• Pharmacological agents as indicated : bronchodilators to reduce bronchial spasm,
antigen for infection.
• Pulmonary hygienic measures to rid respiratory tract of mucosa and purulent
drainage .
• Adequate hydration : 2-3L /day to keep mucous membrane moist & facilitate
removal of secretion
• Supplemental oxygen Is used as necessary
• Mechanical respirator used cautiously (overzealous use may cause rapid
excretion of CO2 ,kidneys will be unable to eliminate excess bicarbonate ,to
prevent alkalosis and convulsions ) for this reason PaCO2 must be decreased
slowly.

13. Respiratory Alkalosis
• Respiratory alkalosis is a primary deficit of carbonic acid in ECF .it is result of the
increased alveolar ventilation and therefore , a decrease in co2 . An increase in
respiratory rate and depth causes the CO2 ,loss because the CO2 is excreted
faster than normal .
• Because of the deficit of the CO2 which is a respiratory stimulant sensed in the
medulla of the brain . Depression of cessation of respiration eventually occur .(
unable to participate in compensation )
• Therefore kidneys attempt to alleviate the imbalance by increasing bicarbonate
excretion and by retaining more hydrogen.
• Respiratory alkalosis = low PaCO2 because of a alveolar hyperventilation

17. Treatment and nursing intervention
• Treatment is correction of underlying causes
• If the cause is anxiety client should made aware that the abnormal
breathing practice is responsible for the symptoms this condition .
• Instruct the client to breath slowly( to cause accumulation of CO2 |)
or to breath in closed system such as paper bag ).
• Sedative required to relieve ventilation in very anxious patients

18. Metabolic Acidosis( Base Bicarbonate Deficit )
• Metabolic acidosis is a proportionate deficit of bicarbonate in ECF. The lungs
attempt to increase the CO2 excretion by increasing the rate and depth of
respirations.
• The kidneys attempt to compensate by retaking bicarbonate and by excreting
more hydrogen .
• If the body is unable to achieve normal balance ,the person may loose
consciousness as metabolic acidosis increases and death eventually result .

20. Metabolic Alkalosis
• Low level of acid or high level of bicarbonates.
• Pathophysiology : Chemical buffers in the ECF and ICF binds bicarbonate that
accumulates in the body . Excessive unbound bicarbonate raises blood PH which
depresses chemoreceptors in the medulla inhibiting respiration and raising
partial pressure.
• When the blood bicarbonate rises to 28 mEq/L or more ,the amount filtered by
the renal glomeruli exceeds the reabsorptive capacity of the renal tubules.
• Excessive bicarbonate is excreted in the urine ,and the hydrogen ions are retained
, To maintain electrochemical balance ,sodium ions and water are excreted with
the bicarbonate ions .

23. Diagnosis
• Blood Ph more7.45
• Bicarbonate more 29 mEq/L
• Partial pressure more than 45 mm Hg
• Low potassium ( 3.5mEq/L )
• LOW CALCIUM ( 8.9mg/dl)
• Low chloride ( 98mEq/L)
• URINE Ph 7
• ECG

25. Treatment and nursing intervention
• Correction of the underlying cause is essential
• Sufficient chloride must be supplied to the kidney to absorb sodium with
chloride .
• Restoration of normal fluid volume by administration of sodium chloride
• Promote self care behaviors to maintain fluids and electrolytes
• Drink eight to ten glasses of water
• Intake and output
• Evaluate food diuretics ,laxatives & alcohols
• Identify situations of high risk for fluid and electrolyte imbalance and
intervention