The Car Accident: A Case Study in Acid-Base Balance

Mr. Henderson, 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. Henderson was having difficulty breathing and complaining 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. Henderson had experienced blunt trauma from the impact of the steering wheel after the airbag failed to deploy.

Mr. Henderson 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).

Define the following terms contained in this case:

Bilateral – Pertains to the right and left sides of a structure; affecting both sides.

Hypoventilation – Breathing at a abnormally slow rate, resulting in decreased oxygen and increased levels of carbon dioxide in the blood.

Hemothorax – A collection of blood in the space between the chest wall and the lung.

Arrhythmias – A condition where the heart beats with a irregular or abnormal rhythm.

What are the normal ranges for the measurements listed in the blood and urine tests? Normal range for blood test should be 7.35-7.45 pH.
Normal range for urinalysis should be 4.5-8 pH.

Explain how Mr. Henderson’s rib fractures are related to the suspected hemothorax. Mr. Henderson had difficulty breathing and was complaining of severe chest pain as well as a large bruise on Mr. Henderson’s chest which indicated where the steering wheel impacted after the airbag failed to deploy. Mr. Henderson’s chest x-rays revealed that he had bilateral fractures in the fourth, fifth, and six ribs which may have penetrated the pleura which may result in a hemothorax.

Mr. Henderson’s PCO2 is elevated. Under normal conditions, what would be the PRIMARY mechanism that his body would use to reduce the amount of PCO2 in the blood? Why is this mechanism not working in this case? Primary mechanism Mr. Henderson should use to reduce the amount of pCO2 in his blood would be to take fast deep breathes. In his case this would prove to be difficult due to the strain from the hemothorax on his respiratory system.

Describe how the high PCO2 and low pH in Mr. Henderson’s blood are related in this case. Mr. Henderson hypoventilation decreased his oxygen to his lungs and that resulted with build up of carbon dioxide.

Describe how the high bicarbonate in Mr. Henderson’s blood is related to the low pH in his urine. The high measure of bicarbonate in Mr. Henderson’s blood caused by hypoventilation causing metabolic acidosis and then causing the ph-urine to lower.

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 PCO2 and blood pH. Best thing would be to stop the source of bleeding and then draining the blood in the thoracic cavity which will allow the lung to expand properly decreasing carbon dioxide and increasing oxygen in the blood to get pH levels back to normal.