A patient has a long history of smoking. He has blood studies done because he is very tired, short of breath, and does not feel well. His blood gases reveal the following findings: pH 7.3, HCO3- 25 mEq/L, PaCO2 48 mmHg. What is the interpretation of these gases?

Select all that apply:

Normal range:

• pH: 7.35-7.45
• PaCO2: 36-44 mmHg
• HCO3-: 22-26 mEq/L

Choice A: Minimal Effect on Vessels

A reduction in blood pH, which indicates acidosis, does not have a minimal effect on blood vessels. Acidosis can significantly impact vascular tone and function. Therefore, this choice is incorrect as it underestimates the physiological changes that occur in response to a decrease in pH.

Choice B: No Effect on Vessels

Similarly, stating that a reduction in blood pH has no effect on vessels is inaccurate. Blood pH is tightly regulated, and deviations from the normal range (7.35-7.45) can lead to significant physiological responses. Acidosis can alter vascular tone, making this choice incorrect.

Choice C: Vasodilation

While vasodilation can occur in response to certain conditions, a reduction in blood pH typically leads to vasoconstriction rather than vasodilation. Vasodilation is more commonly associated with an increase in blood pH (alkalosis) or other factors such as increased levels of nitric oxide or prostaglandins.

Choice D: Vasoconstriction

When the pH of blood reduces, indicating acidosis, it often leads to vasoconstriction. This response is mediated by chemoreceptors that detect changes in pH and stimulate the vasomotor center to increase vascular tone. Vasoconstriction helps to maintain blood pressure and ensure adequate perfusion of vital organs during acidosis. Therefore, this is the correct answer.

Choice A Reason:

Fat necrosis occurs when fatty tissues are damaged, leading to the release of enzymes that break down fat cells. This type of necrosis is commonly seen in the pancreas and breast tissue, often due to trauma or pancreatitis. It is not typically associated with brain tissue.

Choice B Reason:

Coagulative necrosis is characterized by the preservation of the basic outline of the coagulated cells for a few days after cell death. This type of necrosis is usually seen in tissues affected by ischemia, such as the heart, kidneys, and adrenal glands. However, it is not the typical pattern of necrosis seen in brain tissue.

Choice C Reason:

Caseous necrosis is a form of cell death in which the tissue maintains a cheese-like appearance. It is most commonly associated with tuberculosis infections in the lungs. This type of necrosis is not typically seen in brain tissue.

Choice D Reason:

Liquefactive necrosis is the correct answer. This type of necrosis occurs when the tissue becomes soft and liquefied, often forming a pus-filled cavity. It is commonly seen in the brain due to ischemic injury or bacterial infections. The high lipid content and low structural support in brain tissue make it particularly susceptible to liquefactive necrosis.