What are the main respiratory and cardiovascular effects of propofol during induction?

• A. Hypertension and tachycardia
• B. No effect on respiration or blood pressure
• C. Dose-dependent apnea and hypotension
• D. Hyperventilation and decreased gut motility

Answer: (C)

Propofol during induction mainly depresses both respiration and circulation in a dose-dependent way. The apnea comes from suppression of the brain's respiratory centers and relaxation of upper airway muscles, so higher doses or rapid injections can briefly stop breathing unless ventilation is provided. The cardiovascular effect is a dose-related hypotension produced by peripheral vasodilation and some myocardial depression, which lowers systemic vascular resistance and cardiac output. These changes are key reasons for careful titration, pre-oxygenation, and readiness to assist ventilation and fluids during induction. The other options don’t fit because propofol typically causes apnea and hypotension, not hypertension or a complete lack of effect, and hyperventilation is not a characteristic induction effect.