Question

Please answer all parts

Brian, an 80-year-old man with a history of chronic obstructive pulmonary disease (COPD) and respiratory infections, was admitted through the ER with a chronic cough and extreme dyspnea. He complained that he was unable to climb the stairs or anything that required any exertion (even washing his hair). He had been a heavy smoker, but had been attempting to stop smoking by cutting back on the number of cigarettes per day. The nurse noted his temperature was 101.2 °F.

Arterial Blood Gas Results

Test	Brian	Reference Range
pH	7.23	7.35–7.45
PCO2	75.0	35.45 mm Hg
PO2	28.2	83–108 mm Hg
HCO3	32.7	22–28 mEq/L
SaO2	49.6	95–98%
COHb	8.6	Nonsmoker: 0.5–1.5% Smokers: 1–2 packs/day:4–5 % > 2 Packs/day:8–9%

1. What is the primary compensatory mechanism in this acid-base disturbance? (5 points)

2. Would the oxyhemoglobin dissociation curve be shifted? If yes, what direction (right or left)? (5 points)

3. Briefly describe base excess and base deficit. (5 points)

4. What conditions are associated with this acid-base disorder? (5 points)

Answer 1

Primary compensatory mechanism:
  **When there is alveolar hypoventilation there will be Co2 retention..This is due to COPD for this patient..this time PH value will be less,PCO2 increase,HCO3 increase with compensation..Reabsorption of HCO3 by the proximal convoluted tubules increase and it increase the H+ as H2PO4,and NH4+  by the distal convoluted tubule and collecting duct..
Oxyhemoglobin dissociation curve:
** Many physiological factors associated with oxygen dissociation curve either left or right side..unloading oxygen compared to normal curve at the oxygen tension it show rightward shift..If more oxygen loaded it show leftward shift..In this case there is carbondioxide tension made PH less(acidity) and increased 2,3-DPG and increase in temperature shift the curve rightward..
Base excess and base deficit:
** Base excess(BE) in acid base status it measure non-respirator(metabolic)component of acid-base balance. Abnormal base excess indicate metabolic acidosis or metabolic alkalosis..Negative base excess referred to base deficit(BD)..In respiratory acidosis it increase paco2 and reduce PH ,Pco2 increase >45mmHg..so base excess will be normal by (-3 to +3mmol/l) but its utility in interpreting blood gas results in controversial..The Alkalaemia or Acidaemia may be primary or secondary to respiratory acidosis or alkalosis..In this case base excess does not take any appropriate action of metabolic response,it limits its utility when interpreting results..
condition associated with acid-base disorder:
** patient present to the hospital with chronic cough and extreme dyspnea and known case of COPD and respiratory infection..this indicate decreased air movement in the lungs..It is the condition that occur when the lungs can not remove enough co2 due to obstruction (COPD), due to this excess CO2 in the lungs make PH of blood and other body fluid to decrease,making them too acidic..