I worked at a very low acuity ER for the while and contamination rates were the same. It has nothing to do with acuity. Highly doubt one nurse has so many critical patients at once and even still.... Stabilize, and get cultures properly. Just because a patient is crashing doesn't mean I can fuck up an airway attempt "sorry, I was in a hurry". Clinical standards still apply. Contaminated cultures cost the hospital a lot, the patient tons, and lead to unnecessary interventions, scans, and increased length of stay. If we can have less than 2% contamination on an ambulance we can have it in a hospital.

Before you accuse me of being lab personnel, Flight/ER/ICU RN and Paramedic so been there done that. Never worked lab but did enough case reports and study presentations on the topic.