BioMed Central recently featured a pilot study conducted by a team at Japan’s Hitachi General Hospital department of critical care and emergency medicine.
Their pilot study is based on reports that critical ICU patients have at times developed acquired weakness (ICU-AW). The two most prominent illnesses are neuropathy and critical illness myopathy (CIM).
Neuropathy is damage or dysfunction of nerves throughout the body. Whereas CIM is a neuromuscular disorder with muscle weakness caused by muscle fiber dysfunction.
These disorders are receiving attention among critical care personnel as they impact a patient’s quality of life after they have been discharged from ICU.
During and after critical care, a person’s quality of life with aging is impacted by the level of his or her skeletal muscle mass.
A Need for Biomarkers
Although no valid biomarkers exist for ICU-AW, there have been reported cases involving steroids or nondepolarizing neuromuscular blockages as a possible cause.
A neuromuscular block is used in connection with anesthesia. It paralyzes the vocal cords to allow examination of the trachea and also relaxes skeletal muscles.
It has been suggested that these substances are capable of diminishing thick filaments (myosin) in muscle tissue or causing deterioration of muscle fibers.
During a critical illness, a patient may experience muscle atrophy due to an increase in the breakdown of muscle protein and a decrease in the creation of protein molecules (protein synthesis).
Titin, a large protein that functions in striated muscle tissue, is released as fragments in the urine and bloodstream when muscles are damaged. There have been reports that N-terminal (N-titin) fragments are found in the urine of patients with muscular diseases in increased amounts.
These discoveries point to N-titin as a possible noninvasive biomarker in muscle protein breakdown (MPB). The researchers went ahead with a study to evaluate the N-titin levels in patients who were critically ill.
About the Study
The study involved four patients who had been admitted to the ICU in September 2019. Each patient had been living independently prior to their being admitted to the ICU unit.
The researchers measured the Urinary Titin N-fragment level and the change in femoral muscle mass (FMM) with computed tomography (CT).
An assay kit was used to measure Urine N-titin levels which were extremely high when the patients were brought to ICU. The levels remained high during the period of observation with a significant decrease in muscle mass.
It had also been determined through an earlier study that even in healthy individuals, the N-titin levels decrease after the first two weeks of being confined to bed.
The study illustrated high levels of N-titin in patients after being admitted to ICU. Therefore, it would appear that N-titin would be an excellent biomarker for the scientific study of muscle protein breakdown in critical illness myopathy.
A new study is currently underway at the Hitachi Hospital.