The Roy Adaptation Model (1999) provided the overall framework and direction for this
research study. Roy (2009) views the person as an holistic and adaptive system in constant
interaction with the changing environment from which they receive stimuli. The person is
an adaptive system, with cognator and regulator subsystems acting to maintain adaptation
in the four adaptive modes. Critical illness in the ICU may be regarded as the focal stimuli
that affect the cognator (psychologically based) and regulator (physiologically based) subsystems.
The four modes are: physiologic, self-concept, role function, and interdependence.
Critical illness in the ICU affects all four modes of adaptation. The responses in the four
modes are also interrelated. Behaviour, in any mode, can have an effect on, or act as a stimulus
for, one or all of the other modes.