Review of the Accuracy of Two Pain Assessment Tools in Nonverbal Adult Patients

Intensive care units frequently have patients that are unable to verbally communicate their pain, thus negating conventional pain assessment techniques and making pain assessment difficult. Pain management is often a priority in all patients’ circumstances and therefore, assessment and reassessment are included in the plan of care. Different observational pain scales have been used in intensive care units, but often times these scales must be adapted to fit the patient’s circumstances. Pain scales that are used for nonverbal patients typically include behavioral indicators and some are adapted to incorporate physiologic indicators such as vital signs. The aim of this review is to determine if the use of the Critical-Care Pain Observation Tool (CPOT), an assessment tool that is strictly observational, leads to more accurate pain assessment scores for nonverbal adult patients in comparison to the Adult Nonverbal Pain Scale (NVPS), a tool that incorporates vital signs. A search was conducted using five databases and the key words included, but are not limited to, Critical-Care Pain Observation Tool, Adult Nonverbal Pain Scale, nonverbal patients, and pain assessment. It was found that the CPOT was more accurate in determining pain assessment scores due to a discrepancy regarding the inconsistency of vital signs

Kinematic control of extreme jump angles in the red-legged running frog, Kassina maculata

The kinematic flexibility of frog hindlimbs enables multiple locomotor modes within a single species. Prior work has extensively explored maximum performance capacity in frogs; however, the mechanisms by which anurans modulate performance within locomotor modes remain unclear. We explored how Kassina maculata, a species known for both running and jumping abilities, modulates take-off angle from horizontal to nearly vertical. Specifically, how do 3D motions of leg segments coordinate to move the centre of mass (COM) upwards and forwards? How do joint rotations modulate jump angle? High-speed video was used to quantify 3D joint angles and their respective rotation axis vectors. Inverse kinematics was used to determine how hip, knee and ankle rotations contribute to components of COM motion. Independent of take-off angle, leg segment retraction (rearward rotation) was twofold greater than adduction (downward rotation). Additionally, the joint rotation axis vectors reoriented through time, suggesting dynamic shifts in relative roles of joints. We found two hypothetical mechanisms for increasing take-off angle. Firstly, greater knee and ankle excursion increased shank adduction, elevating the COM. Secondly, during the steepest jumps, the body rotated rapidly backwards to redirect the COM velocity. This rotation was not caused by pelvic angle extension, but rather by kinematic transmission from leg segments via reorientation of the joint rotation axes. We propose that K. maculata uses proximal leg retraction as the principal kinematic drive while dynamically tuning jump trajectory by knee and ankle joint modulation

In vitro-virtual-reality: an anatomically explicit musculoskeletal simulation powered by in vitro muscle using closed loop tissue-software interaction

Muscle force-length dynamics are governed by intrinsic contractile properties, motor stimulation and mechanical load. Although intrinsic properties are well-characterised, physiologists lack in vitro instrumentation accounting for combined effects of limb inertia, musculoskeletal architecture and contractile dynamics. We introduce in vitro virtual-reality (in vitro-VR) which enables in vitro muscle tissue to drive a musculoskeletal jumping simulation. In hardware, muscle force from a frog plantaris was transmitted to a software model where joint torques, inertia and ground reaction forces were computed to advance the simulation at 1 kHz. To close the loop, simulated muscle strain was returned to update in vitro length. We manipulated 1) stimulation timing and, 2) the virtual muscle's anatomical origin. This influenced interactions among muscular, inertial, gravitational and contact forces dictating limb kinematics and jump performance. We propose that in vitro-VR can be used to illustrate how neuromuscular control and musculoskeletal anatomy influence muscle dynamics and biomechanical performance

Contractile and elastic behaviour of human muscle-tendon complexes with inertial loading.

Voluntary movement requires that inertial and gravitational forces acting on the limbs be overcome by active muscle-tendon complexes (MTCs). A lot of information exists about the mechanical properties of tendon and the mechanical behaviour of active muscle preparations shortening against constant loads or at constant speeds. During limb movement however, muscles are not expected to shorten at a constant speed or under a constant load as contractions are performed against the series elasticity of the MTC and the inertia of the limbs. This thesis investigates the relationship between the kinetics of inertial and inertial/gravitational loads external to shortening MTCs and the mechanical behaviour of the components of these MTCs. Mathematical modelling revealed the fundamental principles governing the behaviour of MTC- inertial/gravitational load systems. MTC-load model systems behave in a manner, which is largely predictable from the load that is 'sensed' by the MTC. Other factors and their effects have also been identified. It was found that there is an upper limit on the extent to which muscle generated power can be amplified by the elastic properties of tendon. Experimental observations were made of human volunteers performing index finger abduction against purely inertial loads and standing ankle plantar-flexions against inertial/gravitational loads. A method was developed which allows the kinetic behaviour of the components of shortening MTCs to be determined from simple, non-invasive measurements of torque and angular displacement of the moving limbs around their joints. Theoretical and experimental results are compared and critically discussed