A standard technique with potential diagnostic value for estimating the quadriceps muscle strength of critically ill patients.

OBJECTIVE: Intensive care unit-acquired weakness (ICUAW) is common, and so far, there is no digital technology with a standard procedure to estimate the muscle strength of these patients. Quadriceps maximal isometric voluntary contraction (QMVC) is a precise and reliable procedure to detect quadriceps muscle strength. Therefore, this research aimed to explore whether QMVC measurements can be used in critically ill patients at the bedside as a potential diagnostic method.

PATIENTS AND METHODS: Tailor-made computerized equipment was designed to measure the QMVC of critically ill patients at the bedside, following a standard procedure. A total of 22 critically ill patients and 22 age- and sex-matched healthy subjects were divided into group 1 and group 2, respectively. SPASS 21.0 (IBM, Armonk, NY, USA) software was used to analyze the data.

RESULTS: All subjects showed good endurance with the QMVC measurements and there were no side effects among these subjects. There was a significant decline in QMVC between group 1 and group 2 (p=0.000). QMVC was correlated closely with the APACHE II Score in group 1 (Pearson correlation, r=-0.427, p=0.047). Among the 10 patients with a Medical Research Council sum score (MRC SS) less than 60 in group 1, it was also correlated closely with the MRC SS (Pearson correlation, r=0.837, p=0.003).

CONCLUSIONS: This study describes a standard technique for quantifying quadriceps muscle strength that is feasible for use with critical patients. QMVC can accurately detect the decline of quadriceps muscle strength of critical patients, and it may also decline with the severity of the disease. In the future, this technique might be a potential diagnostic tool for ICUAW.