A clinically feasible method for assessing regional splanchnic perfusion is still lacking. Methods used for research purposes demonstrate that the effects of current therapies on splanchnic perfusion are not predictable in intensive care patients with and without ARDS. Tonometry, laser Doppler flowmetry, and spectrophotometry have been used to assess splanchnic perfusion. Combining the available methods in different parts of the gastrointestinal tract may help assess splanchnic perfusion more accurately in the near future.