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![pH = pKₐ + log([A⁻]/[HA])
[A-
] = conjugate base or salt
[HA] = acid
Henderson–Hasselbalch equation](https://image.slidesharecdn.com/acidbaseimbalance-2-241225155205-5836fb4e/75/Acid-base-imbalance-compensations-causes-6-2048.jpg)
![Anion gap : difference between unmeasured anions and
unmeasured cations (only a diagnostic concept)
Plasma anion gap = [Na+
] - [HCO3
-
] - [Cl-
]
= 144 - 24 - 108
= 12 mEq/L
Concentration units : mEq/L or in mmol/L
Anion gap increase if unmeasured anions rise or if unmeasured
cations fall.
Major unmeasured cations :Ca++
,Mg+2
,K+
, gamma globulins
Major unmeasured anions : albumin , phosphate, sulfate, lactate
& other organic anions.
Anion gap range : 8 -16 mEq/L as unmeasured anions exceed
unmeasured cations
Anion gap](https://image.slidesharecdn.com/acidbaseimbalance-2-241225155205-5836fb4e/75/Acid-base-imbalance-compensations-causes-41-2048.jpg)
![Calculation of anion gap: calculated by subtracting the serum
concentrations of chloride and bicarbonate (anions) from the
concentrations of sodium and potassium (cations):
= ( [Na+
]+[K+
] ) − ( [Cl−
]+[HCO3
−
] )
Without potassium (daily practice)
Because potassium concentrations are very low, they usually
have little effect on the calculated gap. omission of potassium
has become widely accepted. This leaves the following equation:
= ( [Na+
] ) − ( [Cl−
]+[HCO3
−
] )
average anion gap for healthy adults : 8-12 mEq/L](https://image.slidesharecdn.com/acidbaseimbalance-2-241225155205-5836fb4e/75/Acid-base-imbalance-compensations-causes-42-2048.jpg)
Acid base imbalance , compensations , causes
- 1.
- 2. Acidosis :pH< 7.35, astate of excess H+ Acidemia :blood pH is <7.35 Alkalosis : pH > 7.45, a state of excess HCO3 - Alkalemia :blood pH is >7.45 Acid-base imbalances
- 4. The body responseto acid-base imbalance is called compensation May be complete if brought back within normal limits 4 Compensation of Acid-Base Imbalances
- 5. If underlying problemis metabolic, hyperventilation or hypoventilation can adjust by respiratory compensation. If problem is respiratory, renal mechanisms can bring about metabolic compensation. 5 Compensation
- 6. pH = pKₐ+ log([A⁻]/[HA]) [A- ] = conjugate base or salt [HA] = acid Henderson–Hasselbalch equation
- 7. when the ratioof HCO3 − to CO2 in the extracellular fluid decreases, decreasing pH . Metabolic acidosis: If this ratio decreases because of a fall in HCO3 − . Respiratory acidosis: If ratio falls because of an increase in PCO2 Acidosis
- 8. Decrease in theratio of HCO3 - to H+ in renal tubular fluid Excess H+ in the renal tubules, complete reabsorption of HCO3 - additional H+ available to combine with the urinary buffers NH4 + and HPO4 - kidneys reabsorb all the filtered HCO3 - contribute new HCO3 - through the formation of NH4 + and titratable acid Respiratory and Metabolic Acidosis
- 9. Metabolic acidosis excess ofH+ over HCO3 - occurs in the tubular fluid primarily due to decreased filtration of HCO3 - caused mainly by a decrease in the extracellular fluid concentration of HCO3 - Respiratory acidosis excess H+ in the tubular fluid due mainly to the rise in extracellular fluid Pco2 , which stimulates H+ secretion
- 11.
- 12.
- 13. Principal effect: depression ofthe CNS through ↓ in synaptic transmission. Generalized weakness Severe acidosis causes ◦Disorientation ◦coma ◦death 13 Acidosis
- 14. Acid-base disturbance Disordertype Primary change in HCO3 - → Metabolic disorder Primary change in blood pCO2 → Respiratory disorder
- 15. Reduction in pHand increase in extracellular fluid H+ concentration increase in Pco2 Compensatory response : Increase in plasma HCO3 − by the addition of new HCO3 − to the extracellular fluid by the kidneys. Rise in HCO3 − helps balances the increase in Pco2 returning the plasma pH toward normal. Respiratory acidosis & its compensation
- 16. Respiratory acidosis Reduction inpH Increase in Pco2 CO2 combines with H2 O to form carbonic acid (H2 CO3 ). Increase in extracellular fluid H+ concentration
- 17. Depression of respiratory center: Decreased ability of the lungs to eliminate CO2 Diseases of the airway : Causes of Respiratory acidosis damage to respiratory center in medulla oblongata stroke infection narcotic poisoning asthma pneumonia emphysema chronic obstructive lung disease airway obstruction diseases of pleura pain killers, benzodiazepines with alcohol, anesthesia, barbiturates, muscle relaxants
- 18. Decreased ability ofthe lungs to eliminate CO2 : Causes of Respiratory acidosis Diseases of the chest : scoliosis, thoracotomy Pulmonary edema, stroke Severe obesity Inadequate ventilation with respiratory or skeletal muscle weakness: poliomyelitis, myasthenia, muscular dystrophies Arteriovenous shunting in poorly ventilated segments of lungs :atelectasis or pneumonitis
- 20. Treatment : Compensatory responsesin respiratory acidosis Buffers of the body fluids Kidneys, require several days to compensate for the disorder • increased reabsorption of HCO3 - by kidneys • increase in plasma HCO3 - • rise in HCO3 - balances the increase in Pco2 , returning the plasma pH toward normal. Administer oxygen Artificial respiration Stimulants of respiratory center
- 21. Decrease in pH Risein extracellular fluid H+ concentration All types of acidosis due to abnormal accumulation of nonvolatile acids in body fluids Primary abnormality : decrease in plasma or ECF HCO3 − . Blood concentrations of bicarbonate :< 24mEq/L Metabolic acidosis
- 22. Failure of thekidneys to excrete metabolic acids normally formed in the body Formation of excess quantities of metabolic acids in the body Addition of metabolic acids to the body by ingestion or infusion of acids Loss of base from the body fluids, same effect as adding an acid to the body fluids. Causes of Metabolic Acidosis
- 23. Specific causes ofMetabolic Acidosis Renal Tubular Acidosis Chronic renal failure Addison’s disease -insufficient aldosterone secretion hereditary and acquired disorders that impair tubular function -Fanconi’s syndrome Diarrhea Diabetes Mellitus Starvation Ketoacidosis
- 24. Hypoxia - lacticacidosis severe muscular exercise cancer shock drugs e.g phenformin, fructose infusion, adrenaline infusion Intake of substances producing acids : methanol, ethylene glycol, acetylsalicylic acid (aspirin) Carbonic anhydrase inhibitors: acetazolamide (Diamox) NH4 Cl Specific causes of Metabolic Acidosis
- 25. Decrease in pH,rise in H+ concentration. Primary abnormality : decrease in plasma HCO3 − Compensations : Respiratory compensation : hyperventilation ( Kussmaul breathing) reduces Pco2 Renal compensation : Complete reabsorption of HCO3 − from renal tubules to the extracellular fluid, helps minimize the initial fall in extracellular HCO3 − concentration adding new HCO3 − to the extracellular fluid, minimize initial fall in extracellular HCO3 − concentration Metabolic acidosis and its compensation
- 26. Treatment: Administer I/V sodiumbicarbonate Correct cause of acidosis Metabolic Acidosis
- 28. ratio of HCO3 - toCO2 in the extracellular fluid increases a rise in pH a decrease in H+ concentration an increase in the ratio of HCO3 - to H+ in the renal tubular fluid. excess of HCO3 - cannot be reabsorbed from the tubules, excreted in the urine. Alkalosis
- 29. over excitability ofthe central and peripheral nervous systems. Numbness Lightheadedness ◦ Nervousness ◦ Muscle spasms or tetany ◦ Convulsions ◦ Loss of consciousness ◦ Death 29 Alkalosis
- 30. Increase pH dueto loss of CO2 from body Excessive ventilation by the lungs low Pco2 and carbonic acid in systemic arterial blood Decrease in H+ concentration due to a decrease in plasma Pco2 and H2 CO3 caused by hyperventilation. Compensation: Chemical buffers of the body fluids Reduction in plasma HCO3 - concentration due to increased renal excretion of HCO3 - Reduction in Pco2 decreased rate of H+ secretion by the renal tubules. reduced amount of H+ in the renal tubular fluid to react with all HCO3 - that is filtered HCO3 - excreted in urine ,decreased plasma HCO3 - concentration and correction of alkalosis Increased distal tubular reabsorption of Cl- Increased secretion of K + into tubular lumen Respiratory alkalosis
- 31. Treatment ◦ One simpletreatment to breathe into paper bag for short time ◦ Reassurance and psychological support
- 32. Psychoneurosis most common Highaltitude ( physiologic type) Hypoxia : i. acute :asthma, pneumonia , pulmonary edema, hypotension ii. chronic : pulmonary fibrosis, severe anemia ,cyanotic heart disease Respiratory center stimulation: i. Apprehension , Severe anxiety, hysteria , tension, pain ii. Hepatic failure iii. Head injury, CNS tumors iv. Aspirin overdose/salicylate poisoning v. Septicemia, fever, heat exposure vi. Pregnancy Excessive mechanical ventilation Causes of Respiratory Alkalosis
- 33. Copyright 2009, JohnWiley & Sons, Inc.
- 34. Increase in pH Decreasedplasma H+ concentration Primary cause :Increase in the extracellular fluid HCO3 − concentration Excess retention of HCO3 − or loss of H+ from body Hypochloremia Hypokalemia Bicarbonate excess -concentration in blood > 26mEq/L Metabolic alkalosis
- 35. Respiratory compensation :decreased ventilation, which increases Pco2 returns ECF pH towards normal Increased ECF HCO3 − Increased filtered load of HCO3 − Excess HCO3 − over H+ secreted in renal tubular fluid Excess HCO3 − in renal tubular fluid fails to be reabsorbed as there is no H+ to react with it and is excreted in urine Increased renal HCO3 − excretion compensating initial rise in ECF HCO3 − concentration Compensation of metabolic alkalosis
- 36. Treatment : Correct causeof alkalosis Give fluid solutions to correct Cl-, K+ and other electrolyte deficiencies Metabolic alkalosis
- 37. Use of diureticsexcept carbonic anhydrase inhibitors Vomiting of acidic stomach contents or gastric drainage Excess aldosterone:primary aldosteronism, administration of steroids , Cushing syndrome Excessive intake of alkaline drugs like antacids Potassium deficiency Severe dehydration Excessive sodium citrate administration in multiple blood transfusions 37 Causes of metabolic Alkalosis
- 38. Copyright 2009, JohnWiley & Sons, Inc.
- 39. Evaluate ◦ systemic arterialblood pH ◦ concentration of bicarbonate (too low or too high) ◦ PCO2 (too low or too high) Solutions ◦ if problem is respiratory, the pCO2 will not be normal ◦ if problem is metabolic, the bicarbonate level will not be normal Principles of Human Anatomy and Physiology, 11e 39 Diagnosis of Acid-Base Imbalances
- 41. Anion gap :difference between unmeasured anions and unmeasured cations (only a diagnostic concept) Plasma anion gap = [Na+ ] - [HCO3 - ] - [Cl- ] = 144 - 24 - 108 = 12 mEq/L Concentration units : mEq/L or in mmol/L Anion gap increase if unmeasured anions rise or if unmeasured cations fall. Major unmeasured cations :Ca++ ,Mg+2 ,K+ , gamma globulins Major unmeasured anions : albumin , phosphate, sulfate, lactate & other organic anions. Anion gap range : 8 -16 mEq/L as unmeasured anions exceed unmeasured cations Anion gap
- 42. Calculation of aniongap: calculated by subtracting the serum concentrations of chloride and bicarbonate (anions) from the concentrations of sodium and potassium (cations): = ( [Na+ ]+[K+ ] ) − ( [Cl− ]+[HCO3 − ] ) Without potassium (daily practice) Because potassium concentrations are very low, they usually have little effect on the calculated gap. omission of potassium has become widely accepted. This leaves the following equation: = ( [Na+ ] ) − ( [Cl− ]+[HCO3 − ] ) average anion gap for healthy adults : 8-12 mEq/L
- 43. Use of aniongap Diagnose different causes of metabolic acidosis Increased Anion Gap (Normochloremia) Normal Anion Gap (Hyperchloremia) Diabetes mellitus (ketoacidosis) ,Starvation Diarrhea Lactic acidosis Renal tubular acidosis Chronic renal failure Carbonic anhydrase inhibitors Aspirin (acetylsalicylic acid) poisoning Addison’s disease Methanol poisoning Ethylene glycol poisoning
- 44. In metabolic acidosis,plasma HCO3 − reduced. If the plasma sodium concentration unchanged, the concentration of anions (either Cl − or an unmeasured anion) must increase to maintain electroneutrality. Hyperchloremic metabolic acidosis: If plasma Cl − increases in proportion to the fall in plasma HCO3 − , the anion gap will remain normal. Normochloremic metabolic acidosis :If the decrease in plasma HCO3 − is not accompanied by increased Cl − , there must be increased levels of unmeasured anions and an increase in the calculated anion gap. Metabolic acidosis caused by excess nonvolatile acids (besides HCl), such as lactic acid or ketoacids, associated with an increased plasma anion gap because the fall in HCO3 − is not matched by an equal increase in Cl − .
- 45. Excess of phosphate,sulfate, acetoacetate, lactate Organic anions in uremic patients Salicylates Lithium intoxication Presence of cationic proteins-immunoglobulins Decrease of serum albumin-nephrotic syndrome Factors affecting anion gap
- 46. Base excess andBase deficit refer to an excess or deficit, respectively, in the amount of base present in the blood. Concentration units : mEq/L, with positive numbers indicating an excess of base and negative a deficit. A typical reference range for base excess: −2 to +2 mEq/L Base excess
- 47. Predominant base inbase excess: bicarbonate Base excess : amount of strong acid that must be added to each liter of fully oxygenated blood to return the pH to 7.40 at a temperature of 37°C and a pCO2 of 40 mmHg . Base deficit (i.e., a negative base excess) correspondingly defined in terms of the amount of strong base that must be added.
- 48. Q. A 15year old boy presents with acute breathlessness. Lab report shows : Blood Reference Range pH 7.10 7.35-7.45 pCO₂ 12.2 4.6--- 6.0 kPa pO₂ 10.1 12-16 kPa Actual Bicarbonate 22 22-30mmol/l Interpret the above case and justify the type of acid base disorder the patient is suffering from. Q. What is the role of renal buffers in maintaining plasma pH? Q. ** Write down the various roles of kidney in acid base balance. Q. Renal mechanisms in acid base balance. Q. How the hemoglobin in RBC regulates acid base balance? Q. Bicarbonate is the major buffer component of plasma. Give the role of kidney in relation to reabsorption and synthesis of bicarbonate. Important questions
- 49. Q. A 24-year-olddiabetic male was brought to emergency room. His blood glucose level on arrival was 780mg%.He had been started on an insulin drip and had received one amp. of bicarbonate. ABG results are : pH= 7.33 (N:7.34-7.45) paCO₂= 25 (N:35-45) HCO₃ =12 (N:22-26) PaO₂ = 89 i-What acid base imbalance is this patient suffering from? ii. Is it compensated? Justify your answer. Q. What is anion gap? What is its normal value? Important questions
- 50. Q. A youngmale was admitted in emergency room of a hospital with severe chest injury after a road traffic accident. i-what kind of acid base problem can be faced by him due to difficulty in chest movement caused by severe pain? ii. Explain the reason of this problem. Q. A 24 year old girl presented to emergency room with a panic attack. She had noticed perioral anesthesia. On examination she was found to be hyperventilating. Her ABG results suggested that she had developed Respiratory Alkalosis. i. Enlist any four causes of Respiratory Alkalosis .How it is compensated ? ii. What is plasma anion gap? Q. What are various types of acids present in body? Q. What is chloride shift, give its importance? Important questions
- 51. Q. A 52year old male patient enters the emergency department complaining of shortness of breath and tingling in fingers .His breathing is shallow and rapid. He denies diabetes ; blood sugar is normal. He has no significant respiratory or cardiac history .He takes several antianxiety medications . he says he has had anxiety attacks before .While being worked up for chest pain an ABG is done and results are : pH = 7.48 (N = 7.34 -7.45 ),PaCO2 = 28mmHg (N=35-45 mmHg) HCO3 = 22mEq/L(22-26 mEq/L) ,paO2 = 85 mmHg He has acid base imbalance .Give your diagnosis . Define alkaline tide? Important questions
- 52. Q. A 21year old girl was admitted to the casualty department with a history of excessive panadol intake .On examination found to be hyperventilating .Blood results are as follows : Plasma sodium 134 mmol/l,Potassium 6 mmol/l, bicarbonate 10mmol/l, chloride 93 mmol/l ,Glucose 3.5 – 6.0 mmol/l ,pH 7.35 -7.45 ,Pa CO2 4.6-6.0 ,3.18 kPa, PaO2 9.3 – 13.33.18 kPa. What is the most probable diagnosis ? Calculate anion gap . Q. A patient of chronic asthma is presented to OPD. Her arterial blood gas analysis showed pH= 7.08 (7.37 to 7.43), pCO2= 38mmHg (37 to 43 mmHg) and HCO3= 18mEq/L (24 to 28 mEq/L). what acid base imbalance this patient is having? What is the reason of low HCO3 levels?
- 53. Paracetamol is aregularly prescribed analgesic and antipyretic due to its low side-effect profile; however it can result in accumulation of 5-oxoproline in individuals who are predisposed to reduced glutathione levels, leading to high anion gap metabolic acidosis.
- 54. The “alkaline tide”that occurs after a meal refers to the transient rise in plasma and urinary pH resulting from efflux of HCO3− from parietal cells into blood in exchange for Cl−, then secretion of HCl into the stomach lumen during gastric secretion. The “alkaline tide” (and by extension, the “acidic tide”) may serve as a signaling mechanism to prime other parts of the body to deal with the consequences of feeding. Alkaline Tide