I would like to thank Stephen D. Reimers, MS, PE for this article.
What flow rate to use with a patient hood is a question with many implications. Hood flow rate primarily affects patient inspired CO2 levels, humidity level, hood noise level and oxygen consumption. It can also have substantial effects on breathing pressures and patient comfort. For many years, “standard practice” for management of patient hoods had been to supply them with a steady flow of about 28 to 30 actual liters per minute (alpm, actual volumetric liters at chamber conditions) regardless of the size of the patient. However, the scientific basis for that practice is obscure.