Physical capacities assessment in critically ill patients: An exploratory study.

Background: The severity of muscle weakness after critical illness is very heterogeneous. To identify those patients who may maximally benefit from early exercises would be highly valuable. This implies an assessment of physical capacities, comprised at least of strength measurement and functional tests.

Objectives: The objective of this study was to investigate the relationship between muscle strength and functional tests in an intensive care unit (ICU) setting.

Methods: Adults with ICU length of stay ≥2 days were included. Handgrip strength (HG) and maximal isometric quadriceps strength (QS) were assessed using standardised protocols as soon as patients were alert and able to obey commands. At the same time, their maximal level of mobilisation capabilities and their autonomy were assessed using ICU Mobility Scale (ICU-MS) and Barthel Index, respectively.

Results: Ninety-three patients with a median age of 64 [57-71.5] years, body mass index of 26.4 [23.4-29.6] kg/m, and Simplified Acute Physiology Score II of 33 [27.7-41] were included. Absolute and relative QS were, respectively, 146.7 [108.5-196.6] N and 1.87 [1.43-2.51] N/kg. HG was 22 [16-31] kg. The ICU-MS score was 4 [1-5]. A significant positive correlation was observed between HG and absolute QS (r = 0.695, p < 0.001) and between HG and relative QS (r = 0.428, p < 0.001). The ICU-MS score correlated with HG, with a weak positive relationship (r = 0.215, p = 0.039), but not with QS. The ICU-MS score did not statistically differ between the weakest and strongest patients for absolute or relative QS, but was lower in patients with the lowest HG values (p = 0.01). A weak positive correlation was observed between the Barthel Index and muscle strengths (maximum r = 0.414, p < 0.001).

Conclusions: The present results suggest that, during ICU stay, there is no strong association between muscle strength and functional test such as the ICU-MS or Barthel Index. Muscle dynamometry and functional tests are probably complementary tools for physical capacities quantification.