Infrared spectroscopy (IR) is a technique used to identify and study the chemical bonds and functional groups in molecules. It works by measuring the absorption or transmission of infrared radiation by a sample, which is related to the vibrational modes of the chemical bonds in the sample. IR spectroscopy can be used to identify unknown compounds, determine the purity of a sample, and monitor chemical reactions. It is widely used in chemistry, biochemistry, and materials science, among other fields. In the context of medical applications, a variant of IR spectroscopy called near-infrared spectroscopy (NIRS) is used to measure hemoglobin oxygenation in tissues. NIRS uses near-infrared light to penetrate tissue and measure the absorption of light by hemoglobin, which is related to its oxygenation state. While IR spectroscopy and NIRS have been used in medical applications, they are not commonly used to assess gastrointestinal function. Transcutaneous NIRS has been used to assess liver perfusion in critically ill children. However, there are several limitations, such as accessibility of the liver, inter-individual variation of single point tissue oxygenation, subcutaneous fat and edema.
References: [1]
1. Shim MG, Song LM, Marcon NE, Wilson BC: In vivo near-infrared Raman spectroscopy: demonstration of feasibility during clinical gastrointestinal endoscopy. Photochem Photobiol 2000, 72(1):146-150.