Abstract: A method of guiding the care of a critically ill patient or other high risk patient, said method comprising administering an effective dose of a gastric acid stimulant or suppressant agent and then measuring for an acute change in the gastric juice pH. A patient who demonstrates a significant change in the gastric juice pH using this test can have their medical care normalized in an accelerated fashion thereby reducing the duration, intensity, and cost of their care. Conversely, a patient who is not responsive is not ready for reduced support and may require more support.