Under what condition is it most critical to maintain a proper seal with an infant resuscitator mask?

Maintaining a proper seal with an infant resuscitator mask is most critical when providing positive pressure ventilation. In this scenario, the goal is to deliver adequate breaths to the infant’s lungs, ensuring that sufficient air (or oxygen) reaches the alveoli for effective gas exchange.

A proper seal is essential because any leaks around the mask can lead to ineffective ventilation. Air can escape instead of being delivered into the infant's airway, which would diminish the effectiveness of the resuscitation efforts and potentially worsen the infant’s condition. Proper sealing ensures that the pressure generated during ventilation is directed into the lungs rather than escaping into the environment.

Other scenarios, such as during split-second assessments or monitoring vital signs, do not require the same level of seal integrity since they do not involve active ventilation. Similarly, under low oxygen supply conditions, while oxygen delivery is important, the focus in resuscitation is on ensuring effective ventilation rather than just managing the oxygen supply directly. Maintaining a seal is paramount during positive pressure ventilation to achieve the necessary respiratory support for the infant.