Which of the following terms correctly defines tachypnea?

• A. Hyperventilation
• B. Bradypnea
• C. Abnormally rapid breathing
• D. Apnea

Answer: (C)

Tachypnea is defined by an increased respiratory rate—the breaths come more quickly than normal. The important point is pace, not necessarily depth of each breath. In adults, this means a rate higher than normal, typically over about 20 breaths per minute. That’s why the description “abnormally rapid breathing” fits tachypnea best. Hyperventilation can involve rapid breathing but also usually implies excessive ventilation relative to metabolic needs and often deeper breaths with CO2 loss; tachypnea, by contrast, is about rapidity of breaths. Bradypnea means slow breathing, and apnea is the complete absence of breathing.