The ICU has been compared to a balloon—able to expand and accommodate patients in greater numbers and rising acuity up to a certain point, but beyond that point, the ICU becomes overwhelmed and care delivery deteriorates. Carrying this analogy further, we can ask several questions about the forces that lead the balloon to pop, or what some have called “ICU capacity strain”: What factors increase pressure inside the balloon? What happens when the balloon pops? And what enables certain balloons to be more elastic than others? Understanding these phenomena can help us build ICUs that can swell and contract more readily in response to the dynamic nature of critical illness.