Brad Bemiss, MD                  Chief Resident.        Department of MedicineLoyola University Medical Center            ...
 Acidemia = pH<7.36 Alkalemia = pH>7.44 Change in pCO2 = Primary respiratory disorder Change in HCO3 = Primary metabol...
Primary Disorder          pH     Primary   Compensator                        Change   Change     y ChangeRespiratory Acid...
Acidosis                                          Alkalosis          Metabolic               Respiratory           Metabol...
Acidosis                     Alkalosis      Metabolic      Respiratory   Metabolic    Respiratory1. Gap or no gap? High AG...
   Caused by loss of HCO3 or accumulation of acid    (e.g. lactate) in the ECF1. Calculate  anion gap2. Check for respira...
   [anions] = [cations]Cl + HCO3 + unmeas anions = Na + unmeas cationsNa - Cl- HCO3 = unmeas anions – unmeas cations     ...
   Most of anion gap made up of albumin   Low albumin  smaller anion gap       i.e., albumin 2g/dL  “normal gap” = 7...
 Methanol (formic acid) Uremia (ESRD  impaired H+ secretion) DKA Paraldehyde INH, Inborn errors of metabolism Lacti...
 Circulatory shock Sepsis Thiamine deficiency Meds (metformin, nitroprusside, NRTIs, tylenol) Propylene glycol toxici...
   Metabolic acid-base disorder  almost immediate    ventilatory responseWinter’s Formula:     Expected pCO2 = 1.5 x [HC...
   Assess for non-gap metabolic acidosis or    metabolic alkalosis        ∆anion gap       meas AG - 12            ∆HCO3 ...
   If no clear explanation for high anion gap    metabolic acidosis, check osmolar gap Osm gap = measured osm – calc osm...
Acidosis                       Alkalosis      Metabolic           Respiratory   Metabolic    Respiratory1. Gap or no gap? ...
 U reterostomy S mall bowel fistula E ndocrine (adrenal insufficiency) D iarrhea C arbonic anhydrase inhibitors A li...
 Renal (RTA, early renal insufficiency) Acetazolamide, ammonium chloride,    hyperal (TPN) Gastrointestinal (diarrhea, ...
2.Check for respiratory compensation with Winter’sformula:    Expected pCO2 = 1.5 x [HCO3] + 8 +/- 23.GI loss verses renal...
   Urine Na + K – Cl   Normal gap is zero or slightly positive   Negative urine anion gap (-20 to -50) indicates GI    ...
Acidosis                           Alkalosis          Metabolic          Respiratory    Metabolic     Respiratory1. Gap or...
 Volume   contraction ◦ Vomiting ◦ Diuretics ◦ Dehydration NGT  suction Hypokalemia Post-hypercapnia Glucocorticoid e...
   Metabolic acid-base disorder  almost immediate    ventilatory responseExpected pCO2 = 0.7 x [HCO3] + 21 +/- 2   Appr...
Chloride Responsive   Chloride Unresponsive    Urine Cl<15            Urine Cl >25
Chloride Responsive     Chloride Unresponsive        Urine Cl<15              Urine Cl >25•   Vomiting•   Diuretics•   Deh...
Chloride Responsive      Chloride Unresponsive        Urine Cl<15               Urine Cl >25•   Vomiting                • ...
Acidosis                                                 Alkalosis          Metabolic                 Respiratory         ...
   Lung disease    ◦ Asthma/COPD    ◦ Pulmonary edema/Pneumonia    ◦ ARDS   Depression of respiratory center    ◦ Drug o...
 Anxiety Drugs    ◦ Salicylate overdose    ◦ Progesterone Pregnancy Liver disease Head injury
∆ pCO2   ∆ pH              Acute      ↑ 10    ↓ 0.08Respiratory Acidosis     Chronic    ↑ 10    ↓ 0.03              Acute ...
∆ pCO2   ∆ HCO3              Acute      ↑ 10     ↑1Respiratory Acidosis     Chronic    ↑ 10     ↑4              Acute     ...
 IfpH is lower than expected pH, metabolic  acidosis  ◦ Don’t forget to measure the gap! If   pH is higher than expected...
Acidosis                                          Alkalosis          Metabolic               Respiratory           Metabol...
Metabolic alkalosis 2/27.58/49/80        hypokalemia145 86 81.9 40 0.7Albumin 3.8Urine Chloride = 74
• Acute respiratory7.52/19/244     alkalosis              • Anion gap metabolic140 112 10      acidosis2.8 19 0.7Albumin 1...
• Anion gap metabolic7.12/19/92      acidosis              • Non-gap metabolic140 108 35      acidosis3.8 6 2.1           ...
Chronic respiratory7.35/60/146   acidosis145 102 503.8 33 1.8Albumin 2.3
• Anion gap metabolic7.14/45/86      acidosis              • Respiratory acidosis140 98 503.0 17 2.6    • Metabolic alkalo...
• Acute respiratory7.59/21/154     alkalosis              • Anion gap metabolic127 79 12       acidosis3.7 20 0.5         ...
Upcoming SlideShare
Loading in...5
×

Acid Base Status

1,037

Published on

0 Comments
12 Likes
Statistics
Notes
  • Be the first to comment

No Downloads
Views
Total Views
1,037
On Slideshare
0
From Embeds
0
Number of Embeds
0
Actions
Shares
0
Downloads
0
Comments
0
Likes
12
Embeds 0
No embeds

No notes for slide
  • If pH, HCO3 and pCO2 all change in the same direction, it is a primary metabolic disorder Compensatory change will not completely correct the pH, just limits the severity of the change in PH
  • Degree of elevated lactate directly correlates with mortality in shock used in ativan, valium, esmolol, NTG and dilantin drips In asthma, there is increased lactate produced by resp muscles)
  • - (mediated by chemoreceptors in carotid body  inc or dec ventilation to affect pCO2)
  • Can also be seen in AKA, DKA, lactic acidosis and CRF
  • Loss of HCO3 is counterbalance by gain of Cl = normal anion gap Ureterostomy is fistula between ureter and GI tract Saline - saline  increased [Cl] in ECF  increased loss of HCO3 in urine
  • Contraction alkalosis Kidneys increase Na reabsorption accompanied by HCO3 reabsorption increased aldo  increased H+ secretion Post-hypercapnia During respiratory acidosis, the kidneys reabsorb bicarbonate and secrete chloride to compensate for the acidosis. In the posthypercapnic state, urine chloride is high and can lead to chloride depletion. Once the respiratory acidosis is corrected, the kidneys cannot excrete the excess bicarbonate because of the low luminal chloride. Acids in infusions (lactate, acetate and citrate) converted to bicarbonate
  • Contraction alkalosis Kidneys increase Na reabsorption accompanied by HCO3 reabsorption increased aldo  increased H+ secretion Post-hypercapnia During respiratory acidosis, the kidneys reabsorb bicarbonate and secrete chloride to compensate for the acidosis. In the posthypercapnic state, urine chloride is high and can lead to chloride depletion. Once the respiratory acidosis is corrected, the kidneys cannot excrete the excess bicarbonate because of the low luminal chloride. Acids in infusions (lactate, acetate and citrate) converted to bicarbonate
  • Contraction alkalosis Kidneys increase Na reabsorption accompanied by HCO3 reabsorption increased aldo  increased H+ secretion Post-hypercapnia During respiratory acidosis, the kidneys reabsorb bicarbonate and secrete chloride to compensate for the acidosis. In the posthypercapnic state, urine chloride is high and can lead to chloride depletion. Once the respiratory acidosis is corrected, the kidneys cannot excrete the excess bicarbonate because of the low luminal chloride. Acids in infusions (lactate, acetate and citrate) converted to bicarbonate
  • Acid Base Status

    1. 1. Brad Bemiss, MD Chief Resident. Department of MedicineLoyola University Medical Center 2012.
    2. 2.  Acidemia = pH<7.36 Alkalemia = pH>7.44 Change in pCO2 = Primary respiratory disorder Change in HCO3 = Primary metabolic disorder
    3. 3. Primary Disorder pH Primary Compensator Change Change y ChangeRespiratory Acidosis pCO2 HCO3Respiratory Alkalosis pCO2 HCO3 Metabolic Acidosis HCO3 pCO2 Metabolic Alkalosis HCO3 pCO2
    4. 4. Acidosis Alkalosis Metabolic Respiratory Metabolic Respiratory1. Gap or no gap? 1. Acute or chronic? 1. Check for 1. Acute or chronic? respiratory compensation High AG Normal AG Acute Chronic Acute Chronic 2. Measure2a. Winters 2b. Winters 10 ∆pCO2: 10 ∆pCO2: urine 10 ∆pCO2: 10 ∆pCO2: chloride3a. ∆/∆ 3b. Urine - pH ↓ by - pH ↓ by - pH ↑ by - pH ↑ by anion gap 0.08 0.03 0.08 0.034a. Osmol.gap - HCO3 ↑ - HCO3 ↑ - HCO3 ↓ - HCO3 ↓ by 1 by 4 by 2 by 5 2. If expected pH does 2. If expected pH does not equal actual pH, not equal actual pH, superimposed metabolic superimposed metabolic process process
    5. 5. Acidosis Alkalosis Metabolic Respiratory Metabolic Respiratory1. Gap or no gap? High AG2a.Winters3a. ∆/∆4a. Osmol.gap
    6. 6.  Caused by loss of HCO3 or accumulation of acid (e.g. lactate) in the ECF1. Calculate anion gap2. Check for respiratory compensation3. Check for co-existing non-gap acidosis or metabolic alkalosis4. If gap acidosis and no clear reason for gap, measure osmolar gap
    7. 7.  [anions] = [cations]Cl + HCO3 + unmeas anions = Na + unmeas cationsNa - Cl- HCO3 = unmeas anions – unmeas cations Normal anion gap = 12
    8. 8.  Most of anion gap made up of albumin Low albumin  smaller anion gap  i.e., albumin 2g/dL  “normal gap” = 7 For every 1g/dL below 4g/dL (nl albumin), add 2.5 to the gap or Adj gap = calc gap + 2.5 (4-meas albumin)
    9. 9.  Methanol (formic acid) Uremia (ESRD  impaired H+ secretion) DKA Paraldehyde INH, Inborn errors of metabolism Lactic acid Ethylene glycol (oxalic acid) Salicylates (salicylic acid)
    10. 10.  Circulatory shock Sepsis Thiamine deficiency Meds (metformin, nitroprusside, NRTIs, tylenol) Propylene glycol toxicity (used in ativan drips) Hepatic insufficiency Seizures Acute asthma attacks
    11. 11.  Metabolic acid-base disorder  almost immediate ventilatory responseWinter’s Formula: Expected pCO2 = 1.5 x [HCO3] + 8 +/- 2 Appropriate compensation  measured pCO2 = exp pCO2 Respiratory alkalosis  measured pCO2 < exp pCO2 Respiratory acidosis  measured pCO2 > exp pCO2
    12. 12.  Assess for non-gap metabolic acidosis or metabolic alkalosis ∆anion gap meas AG - 12 ∆HCO3 24 – meas HCO3 ◦ <1 = non gap acidosis ◦ >1 = metabolic alkalosis Measured HCO3 + ∆gap = 24 ◦ <24 = non gap acidosis ◦ >24 = metabolic alkalosis
    13. 13.  If no clear explanation for high anion gap metabolic acidosis, check osmolar gap Osm gap = measured osm – calc osm Calc osm = 2(Na) + Gluc + BUN 18 28 Normal Osm gap = 10-15 >25 suggests methanol or ethylene glycol poisoning
    14. 14. Acidosis Alkalosis Metabolic Respiratory Metabolic Respiratory1. Gap or no gap? High AG Normal AG2a. Winters 2b. Winters3a. ∆/∆ 3b. Urine4a. Osmol. anion gapgap
    15. 15.  U reterostomy S mall bowel fistula E ndocrine (adrenal insufficiency) D iarrhea C arbonic anhydrase inhibitors A limentation (TPN) R TA S aline
    16. 16.  Renal (RTA, early renal insufficiency) Acetazolamide, ammonium chloride, hyperal (TPN) Gastrointestinal (diarrhea, fistulas) Endocrine (adrenal insufficiency)S aline
    17. 17. 2.Check for respiratory compensation with Winter’sformula: Expected pCO2 = 1.5 x [HCO3] + 8 +/- 23.GI loss verses renal loss of HCO3?  Urine anion gap
    18. 18.  Urine Na + K – Cl Normal gap is zero or slightly positive Negative urine anion gap (-20 to -50) indicates GI losses (ne-GUT-ive) ◦ Diarrhea ◦ Fistulas
    19. 19. Acidosis Alkalosis Metabolic Respiratory Metabolic Respiratory1. Gap or no gap? 1. Check for respiratory compensation High AG Normal AG 2. Measure2a. Winters 2b. Winters urine chloride3a. ∆/∆ 3b. Urine anion gap4a. Osmol.gap
    20. 20.  Volume contraction ◦ Vomiting ◦ Diuretics ◦ Dehydration NGT suction Hypokalemia Post-hypercapnia Glucocorticoid excess
    21. 21.  Metabolic acid-base disorder  almost immediate ventilatory responseExpected pCO2 = 0.7 x [HCO3] + 21 +/- 2 Appropriate compensation  measured pCO2 = exp pCO2 Respiratory alkalosis  measured pCO2 < exp pCO2 Respiratory acidosis  measured pCO2 > exp pCO2
    22. 22. Chloride Responsive Chloride Unresponsive Urine Cl<15 Urine Cl >25
    23. 23. Chloride Responsive Chloride Unresponsive Urine Cl<15 Urine Cl >25• Vomiting• Diuretics• Dehydration• Continuous NG suction• Post-hypercapnia
    24. 24. Chloride Responsive Chloride Unresponsive Urine Cl<15 Urine Cl >25• Vomiting • Pure hypokalemia• Diuretics • Mineralocorticoid excess• Dehydration• Continuous NG suction• Post-hypercapnia
    25. 25. Acidosis Alkalosis Metabolic Respiratory Metabolic Respiratory1. Gap or no gap? 1. Acute or chronic? 1. Check for 1. Acute or chronic? respiratory compensation High AG Normal AG Acute Chronic Acute Chronic 2. Measure2a. Winters 2b. Winters 10 10 urine 10 10 ∆pCO2: ∆pCO2: chloride ∆pCO2: ∆pCO2:3a. ∆/∆ 3b. Urine anion gap - pH ↓ by - pH ↓ by - pH ↑ by - pH ↑ by4a. Osmol. 0.08 0.03 0.08 0.03gap - HCO3 ↑ - HCO3 ↑ - HCO3 ↓ - HCO3 ↓ by 1 by 4 by 2 by 5 2. If expected pH 2. If expected pH does not equal actual does not equal actual pH, superimposed pH, superimposed metabolic process metabolic process
    26. 26.  Lung disease ◦ Asthma/COPD ◦ Pulmonary edema/Pneumonia ◦ ARDS Depression of respiratory center ◦ Drug overdose ◦ Obesity Hypoventilation Nerve or muscular disorders ◦ Guillain-Barre ◦ Myasthenia gravis
    27. 27.  Anxiety Drugs ◦ Salicylate overdose ◦ Progesterone Pregnancy Liver disease Head injury
    28. 28. ∆ pCO2 ∆ pH Acute ↑ 10 ↓ 0.08Respiratory Acidosis Chronic ↑ 10 ↓ 0.03 Acute ↓ 10 ↑ 0.08Respiratory Alkalosis Chronic ↓ 10 ↑ 0.03
    29. 29. ∆ pCO2 ∆ HCO3 Acute ↑ 10 ↑1Respiratory Acidosis Chronic ↑ 10 ↑4 Acute ↓ 10 ↓2Respiratory Alkalosis Chronic ↓ 10 ↓5
    30. 30.  IfpH is lower than expected pH, metabolic acidosis ◦ Don’t forget to measure the gap! If pH is higher than expected pH, metabolic alkalosis
    31. 31. Acidosis Alkalosis Metabolic Respiratory Metabolic Respiratory1. Gap or no gap? 1. Acute or chronic? 1. Check for 1. Acute or chronic? respiratory compensation High AG Normal AG Acute Chronic Acute Chronic 2. Measure2a. Winters 2b. Winters 10 ∆pCO2: 10 ∆pCO2: urine 10 ∆pCO2: 10 ∆pCO2: chloride3a. ∆/∆ 3b. Urine - pH ↓ by - pH ↓ by - pH ↑ by - pH ↑ by anion gap 0.08 0.03 0.08 0.034a. Osmol.gap - HCO3 ↑ - HCO3 ↑ - HCO3 ↓ - HCO3 ↓ by 1 by 4 by 2 by 5 2. If expected pH does 2. If expected pH does not equal actual pH, not equal actual pH, superimposed metabolic superimposed metabolic process process
    32. 32. Metabolic alkalosis 2/27.58/49/80 hypokalemia145 86 81.9 40 0.7Albumin 3.8Urine Chloride = 74
    33. 33. • Acute respiratory7.52/19/244 alkalosis • Anion gap metabolic140 112 10 acidosis2.8 19 0.7Albumin 1.1Lactate 4.6
    34. 34. • Anion gap metabolic7.12/19/92 acidosis • Non-gap metabolic140 108 35 acidosis3.8 6 2.1 Urine Na = 55Albumin 3.9 Urine K = 5 Urine Cl = 110
    35. 35. Chronic respiratory7.35/60/146 acidosis145 102 503.8 33 1.8Albumin 2.3
    36. 36. • Anion gap metabolic7.14/45/86 acidosis • Respiratory acidosis140 98 503.0 17 2.6 • Metabolic alkalosisAlbumin 3.7
    37. 37. • Acute respiratory7.59/21/154 alkalosis • Anion gap metabolic127 79 12 acidosis3.7 20 0.5 • Metabolic alkalosisAlbumin 4.1

    ×