Final answer:
For proper positive pressure ventilation, the PPV mask should cover both the nose and mouth of the baby to provide efficient breathing support, similar to masks used with CPAP devices in adults.
Step-by-step explanation:
When using positive pressure ventilation (PPV), the mask should properly cover both the nose and mouth of the baby to ensure effective delivery of breaths. This is important because the mask needs to create a seal to pressurize the air being delivered, thereby aiding the baby's breathing efficiently. In a typical Continuous Positive Airway Pressure (CPAP) device, which is used in the treatment of sleep apnea in adults, the mask is affixed to the head with straps, and is designed to cover both the nose and mouth.