Question

Auto Injury : A Case Study in Acid-Base Balance

Mr. Wilson , a 60-year-old male, was on his way home from work after snowing all day. Mr. Wilson slide on the icy street through a red light where he was hit by an oncoming truck. The other driver suffered only minor bruises and cuts, Mr. Wilson demonstrated labored breathing and severe chest pain. Mr. Wilson was in the trauma centers ER in less than 2 mins. Mr. Wilson had experienced blunt trauma from the impact of the steering wheel after the airbag failed to deploy.

Mr. Wilson examination revealed, blurred vision, dizziness, headache, nausea, muscle weakness, hypoventilation, and a feeling of mental confusion. A Ct scan revealed bilateral fractures in the fourth, fifth, and six ribs and a possible 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).

Aterial Blood Gas (ABG)     High or Low

pH:                  7.1                        Low

P_co2:                            58                         High

bicarbonate:    33 mEq/L             High          

Urinalysis (UA)

pH:                  3.7                        Low

Short Answer Questions

1. Mr. Wilsons’s P_CO2 is elevated. Under normal conditions, what would be the PRIMARY mechanism that his body would use to reduce the amount of P_CO2 in the blood? Why is this mechanism not working in this case?

2. Describe how the high P_CO2 and low pH in Mr. Wilson’s blood are related in this case.

3. Describe how the high bicarbonate in Mr. Wilson’s blood is related to the low pH in his urine.

4. What type of intervention might the doctors and nurses initiate in order to address the hemothorax? Explain how this intervention will lead to changes in P_CO2 and blood pH.

Answer 1

1. Under normal condition, respiratory system would have compensated, due to the increased CO2 levels, the lung would hyperventilate by increasing the rate and depth of breathing so that excess CO2 is driven out of the body, this mechanism is not working in this patien because his lungs are not functioning properly due to his condition of Hemothorax.

2. In this case because of hemothorax, there is improper ventilation (breathing) due to which CO2 are not expelled out in the usual quantity as a result there is accumulation of CO2 in the body, too much CO2 combines with water and yielding carbonic acid, which will reduce the pH

3.During respiratory acidosis, the blood is acidic due to too much CO2 combining with water and yielding carbonic acid. Because of this, the kidneys increase the amount of bicarbonate in the blood and secretes hydrogen ions into the tubules to raise the pH and bring it back in its normal range. This increased hydrogen causes pH to decrease.

4. A procedure called Thoracosotomy is performed, in this procedure the blood which is accumulated in the pleural cavity around the lungs and can be drained (usually done by inserting a chest tube). This will help eliminate one of the issues preventing proper ventilation in a condition like hemothorax, once this procedure is done, his breathing can be restored to normal or levels, this increased breathing can expel out CO2 from the body there by restoring normal pH in the blood.