- Vasodilation: Caused by induction agents and gases.
- Myocardial depression: Caused by induction agents.
- Fall in FRC due to loss of muscle tone (due to inward force of elastic lung tissue overwhelming outward force of respiratory muscles), and supine position (abdominal viscera pressing against diaphragm).
- Reduced compliance due to increase in elastic behavior of lungs.
- Poorer oxygenation and ventilation caused by atelectasis secondary to the fall in FRC.
- End expiratory lung volume is reduced from 3.5L to 2L.
- Ketamine does not lead to a loss in muscle tone (and therefore does not reduce FRC).