doc_clotaire
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A 56-year-old male with COPD is brought by family members to the emergency room because of dyspnea and cyanosis. His vital signs are
pulse 95/min,
BP 120/80,
temperature 98.9.
His physical examination shows barrel-shaped chest cavity with hyperresonance by percussion over both lungs.
His CBC and blood gases while breathing room air upon admission are as follows:
PCO2 50 mmHg
PO2 50 mmHg
Serum HCO3- 32 mEq/L
Serum pH 7.45
RBCs 5.1X106/ml
Hemoglobin 13.5 gm/dl
HCT 42%
WBCs 8.8x 103/ml
The patient’s profile is most consistent with
A. Acute metabolic acidosis
B. Acute respiratory acidosis
C. Acute metabolic alkalosis
D. Acute respiratory alkalosis
E. Chronic respiratory acidosis
F. Compensated metabolic acidosis
Edited by new_n_lost on 12/11/07 - 12:55 AM. Reason: Corrected the Format of the Question
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| hope4dabest
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E
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| jean robert
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E ( most likely compensated)
Agree with hope4dabest
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| SURVIVOR
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pH = 7.45. How come thats labelled as acidosis? I'd have gone 4 C. Plz explain your answers!
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| new_n_lost
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Dr_Kashif wrote:
pH = 7.45. How come thats labelled as acidosis? I'd have gone 4 C. Plz explain your answers!
Why dont you explain yours and we all can start from there. 
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| SURVIVOR
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PCO2 50 mmHg
PO2 50 mmHg
Serum HCO3- 32 mEq/L
Serum pH 7.45
RBCs 5.1X106/ml
Hemoglobin 13.5 gm/dl
HCT 42%
WBCs 8.8x 103/ml
Normal pH of Human blood = 7.35 - 7.45
This definitely is on the higher side and so would classify as an alkolosis! No amount of compensation of an acidotic state can lead to an alkolosis..
Next, the HCO3 is raised. This is the most obvious reason for the increased pH.
Moderate respiratory acidosis is also feautured but then its not sever to be reflected in the pH. If this was the ONLY abnormality, however well compensated, the pH would have been below 7.40 at the most!
There is an acute metabolic insult in addition to the chronic respiratory problem! The present profile is consistent with an ACUTE METABOLIC ALKALOSIS on a background of a CHRONIC RESPIRATORY PATHOLOGY!
However well explained, I might be wrong! Now why did you chose E? 
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| new_n_lost
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E. Chronic respiratory acidosis
Based on 2 values that any lab value which is
1. PaCO2 >45mmHg
2. serum HCO3 > 30mEq/L
is undoubtedly Chronic Respiratory acidosis. and FYI pH of 7.45 will still be considered normal.
Me 2 cents.
(ref.Goljan RR pg.77 Table 7-10)
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| Idlehands
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Dr_Kashif wrote:PCO2 50 mmHg PO2 50 mmHg Serum HCO3- 32 mEq/L Serum pH 7.45 RBCs 5.1X106/ml Hemoglobin 13.5 gm/dl HCT 42% WBCs 8.8x 103/ml Normal pH of Human blood = 7.35 - 7.45 This definitely is on the higher side and so would classify as an alkolosis! No amount of compensation of an acidotic state can lead to an alkolosis.. Next, the HCO3 is raised. This is the most obvious reason for the increased pH. Moderate respiratory acidosis is also feautured but then its not sever to be reflected in the pH. If this was the ONLY abnormality, however well compensated, the pH would have been below 7.40 at the most! There is an acute metabolic insult in addition to the chronic respiratory problem! The present profile is consistent with an ACUTE METABOLIC ALKALOSIS on a background of a CHRONIC RESPIRATORY PATHOLOGY! However well explained, I might be wrong! Now why did you chose E?
I m really sorry to say this but your posts seem very cocky. May i ask why the attitude.
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| SURVIVOR
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 You got me wrong!! Sorry if I sounded that way!
tc n thanx new_n_lost.
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| new_n_lost
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Dr_Kashif wrote:
thanx new_n_lost.
I m also waiting for the answer and the explanation 
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| doc_clotaire
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CORRECT: E
Determination of electrolytes, pH and blood gases ideally should be performed on the same specimen or specimens obtained simultaneously, since the acid-base situation is very labile. For judging hypoxemia, it is necessary to know the patient’s hemoglobin or hematocrit value and whether the patient was breathing room air or oxygen when the specimen was drawn. An abnormal bicarbonate level means a metabolic rather than a respiratory disorder. However, the clinical presentation and the relationship of the bicarbonate level to PCO2 and PO2 should be used to decide if the case is a metabolic disorder, compensated respiratory disorder or a combined metabolic and respiratory disorder.
The increased level of PCO2 and decreased PO2 in this patient suggest respiratory acidosis even though the pH is at the upper border of normal. It is important to remember that a normal pH does not rule out an acid-base disturbance. The normal pH in this situation indicates that the condition is compensated. The increased level of the serum bicarbonate that is proportional to the increase in PCO2 confirms that possibility. The patient’s serum bicarbonate is slightly increased but if you compare it to the increased level of PCO2, you can see that these values are consistent with compensated respiratory acidosis.
For every 10-mmHg increase in PCO2, you should expect a 3.5 mEq/L rise in the serum bicarbonate in chronic respiratory acidosis as in this case. The patient’s presentation, blood gases and pH are consistent with chronic respiratory acidosis with compensation.
The increased level of PCO2 and the level of serum bicarbonate rule out the possibility of respiratory alkalosis. The increased level of serum HCO3- must be considered in relation to PCO2 and PO2 to avoid making the mistake of calling this condition metabolic alkalosis. Also, normal pH as well as the increased bicarbonate rules out the possibility of acute respiratory acidosis. The increased bicarbonate and the patient’s presentation rule out the possibility of acute metabolic acidosis. The level of the pH and the serum bicarbonate in relation to the levels of PCO2 and PO2 exclude the possibility of compensated metabolic acidosis.
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| SURVIVOR
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^ excellent ! Thanx doc_clotaire!
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| paheli
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great thread here. thanks guys.
Compensation refers to respiratory and renal mechanisms that bring the arterial pH close to but not in to the normal pH range [7.35 to 7.45] RR by Goljan, 2nd ed, pg 70
he goes on to add:
When compensation brings pH in to the normal range, full compensation is present, which rarely occurs.
i wonder what he meant to say.......
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| Ig F
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E....Chronic Respiratory Acidosis.......
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