The most likely diagnosis is postintensive care syndrome. The patient was severely ill and in an ICU for several days where she was treated for severe sepsis and shock. Postintensive care syndrome is a term used to describe new or worsening function in one or more physical, cognitive, or mental domains that persists after hospital discharge following a critical illness, as in this patient. Examples of clinical findings include cognitive deficits resembling traumatic brain injury or mild cognitive impairment; psychiatric symptoms such as depression, anxiety, and posttraumatic stress disorder (PTSD); and physical deficits such as weakness and fatigue. Although the cause of this syndrome is not understood, possible mechanisms include hypoxia, hypotension, inflammation, the catabolic state, hypoglycemia, other nutritional disorders, immobility, and agents used for sedation. This syndrome may also be applied to symptoms experienced by family members of post-ICU patients who may experience sleep disturbances, anxiety, depression, a complicated grief reaction, and PTSD. The efficacy of preventive measures and treatment interventions is not known, but efforts to maintain light sedation and avoid glycemic extremes and hypoxia may be of benefit. Treatment otherwise focuses on the specific symptoms experienced by the patient or family.

Critical illness neuromyopathy is a generalized axonal sensorineural polyneuropathy associated with severe illness and treatment in an ICU setting. Although it could explain this patient's physical limitations, it is not associated with psychiatric symptoms such as anxiety or cognitive deficits such as difficulty multitasking.

Similarly, prolonged bed rest in patients in the ICU may result in significant deconditioning and physical limitations following recovery from acute illness; however, it would not be expected to cause problems with psychiatric or cognitive function.

Patients treated in the ICU for severe illness are at increased risk for depression, anxiety, and PTSD, which may result in the psychiatric and cognitive symptoms seen in this patient. Generalized anxiety disorder develops over time and is characterized by excessive worrying about many things of little or no need for concern. Sleep disturbances along with anxiety are reasons patients seek help from their physicians. However, this diagnosis would not explain this patient's overall symptom complex, which includes cognitive limitations and physical symptoms such as weakness.