what’s the PRIMARY mechanism that the body uses to regulate PCO2 level in blood? 

Mr. Crabtree, a 52-year-old male, was on his way to work during a heavy rainstorm when he lost control of his car and crossed into oncoming traffic where he collided head-on with a small delivery truck.  Witnesses accessed the 911 emergency medical response system, and paramedics arrived quickly.  The driver of the truck suffered only minor cuts and scrapes, but Mr. Crabtree was having difficulty breathing and complained of severe chest pain.  Transport time to the nearest trauma center was less than two minutes, so the emergency personnel elected to “scoop and haul.”  A large bruise on his chest indicated that Mr. Crabtree had experienced blunt trauma from the impact of the steering wheel after the airbag failed to deploy.

Mr. Crabtree presented in the ER with blurred vision, dizziness, headache, nausea, muscle weakness, hypoventilation, and a feeling of mental confusion.  A chest X ray revealed bilateral fractures in the fourth, fifth, and six ribs along with a suspected hemothorax.  An ECG revealed signs of ventricular arrhythmias.  The values following values were taken from the results of an arterial blood gas (ABG) and urinalysis (UA).

Arterial Blood Gas (ABG)                   High or Low?

pH:                          7.0

PCO2:                       62 mmHg

Bicarbonate:         29 mEq/L

Urinalysis (UA)                                     High or Low?

pH:                          4.0

  2. Identify if the results listed above are higher or lower than normal. What are the approximate normal ranges for the results listed above? [2 POINTS]

  3. Crabtree’s PCO2 is abnormal. Under normal conditions, what’s the PRIMARY mechanism that the body uses to regulate PCO2 level in blood?  Why is this not working for this patient? [2 POINTS]

  4. Describe how the PCO2 and pH in Mr. Crabtree’s blood are related in this case. [2 POINT]
  5. Describe how the bicarbonate in Mr. Crabtree’s blood is related to the pH in his urine. [2 POINTS]

  6. What is the acid-base disturbance in this case? Are there any compensatory mechanisms at play? If so, what are they and how do you know? [2 POINTS]

  7. Although it wasn’t necessary to calculate in this case, what is an anion gap and what acid-base disturbance is associated with a high anion gap? Describe TWO CONDITIONS associated with a high anion-gap? Why does each condition cause a high anion gap (i.e explain why there is an anion gap). [5 POINTS]