Question

John was involved in a motorcycle accident. He complains of difficulty breathing and chest pain. He was diagnosed with pneumothorax. Which arterial blood gas (ABG) would you expect?

1) Decreased pH and increased PaCO₂
2) Increased pH and decreased PaCO₂
3) Decreased pH and decreased PaCO₂
4) Increased pH and increased PaCO₂

Answer 1

John's pneumothorax would likely result in an ABG showing respiratory acidosis, represented by decreased pH and increased PaCO2, due to impaired gas exchange and CO2 retention. The correct option is 1.

Step-by-step explanation:

John was involved in a motorcycle accident and diagnosed with pneumothorax. For a patient with pneumothorax, one would expect the arterial blood gas (ABG) results to show respiratory acidosis due to impaired lung function, which would typically lead to decreased pH and increased PaCO2.

A pneumothorax occurs when air enters the pleural space, the thin fluid-filled space between the two pulmonary pleurae of each lung, causing part or all of a lung to collapse.

As the lung collapses, it cannot effectively exchange gases, leading to the accumulation of carbon dioxide (CO2) in the blood. This excess CO2 lowers the pH, causing acidosis.

Comparatively, in the presented case study, Bob has a pH of 7.31, elevated pCO2, and increased HCO3-, indicating respiratory acidosis with compensation.

Due to his asthma, which likely inhibited his lung function, the body responds by increasing bicarbonate levels in an attempt to compensate and bring the blood pH back towards normal. Similar mechanisms apply to pneumothorax, though the initial trigger for the respiratory issue differs. The correct option is 1.