Which of the following is typically an indication of hyperventilation?

A PaCO2 level less than 35 mmHg is indicative of hyperventilation. Hyperventilation occurs when a person breathes rapidly or deeply, leading to an excessive loss of carbon dioxide (CO2) from the blood. This lowers blood CO2 levels, reducing the partial pressure of carbon dioxide (PaCO2). Normal PaCO2 levels range from approximately 35 to 45 mmHg, so a value below 35 mmHg suggests that the body is expelling CO2 at a rate that surpasses its production, a hallmark of hyperventilation.

Understanding the implications of PaCO2 is crucial in critical care. CO2 plays an important role in regulating blood pH; thus, hyperventilation can lead to respiratory alkalosis, where the blood becomes too alkaline due to the decreased concentration of CO2, impacting overall respiratory and metabolic functions. Monitoring PaCO2 helps clinicians assess a patient's ventilatory status and determine appropriate interventions.