Which condition is described as an abnormal decrease in respiratory rate?

Bradypnea is defined as an abnormal decrease in respiratory rate, typically characterized by a rate that is slower than the normal range of 12 to 20 breaths per minute in adults. This condition can occur in various situations, including drug overdoses, especially with narcotics, brain injuries, or metabolic imbalances. A decrease in respiratory rate may result in insufficient oxygen delivery to the body's tissues, potentially leading to respiratory acidosis or hypoxia.

To clarify the other terms in relation to respiratory rates: apnea refers to a complete cessation of breathing, making it distinctly different from a decreased rate. Tachypnea indicates an abnormally fast respiratory rate, often resulting from conditions such as anxiety or respiratory distress. Eupnea describes normal, unlabored breathing, which is also not applicable in this context since it implies an absence of abnormalities in the respiratory rate.