Patients are more effectively ventilated with face-mask ventilation when:

Effective face-mask ventilation in patients is facilitated by a proper airway and aspiration risk evaluation, a well-functioning pulse oximeter, awareness of patient allergies, and the availability of appropriate equipment. Alveolar ventilation can be maintained constant by adjusting the respiratory rate and volume of air per breath.

Explanation:

Patients are more effectively ventilated with face-mask ventilation when an adequate seal is ensured and when the patient's airway and risk of aspiration have been properly assessed. Knowledge of pulmonary volumes and capacities such as Total lung capacity (TLC), Functional residual capacity (FRC), and Residual volume (RV) is crucial for effective ventilation. It is also essential that the pulse oximeter is functioning to monitor the patient's oxygenation status. Techniques like Continuous positive airway pressure (CPAP) can help maintain an open airway and adequate ventilation. It is important that all members of the medical team are aware of the patient's allergies and the appropriate equipment and assistance are available in case of an emergency.

In regards to alveolar ventilation, it remains constant when either the respiratory rate is increased while the volume of air per breath is decreased, or when both the respiratory rate and the volume of air per breath are increased. This approach helps to avoid ventilation/perfusion (V/Q) mismatch which is crucial for effective gas exchange.