More than 5 million patients in the United States are admitted to intensive care units (ICUs) annually.¹ Mortality rates among these patients decreased by 35% between 1988 and 2012, despite increasing illness severity and increasing patient age; current mortality rates are estimated at 10% to 29%.¹ Because a greater number of patients are surviving to ICU discharge and require follow-up in the outpatient setting, family physicians should be prepared to provide ongoing care and screening for post-ICU complications.

With no universally accepted guidelines, the timing and frequency of post-ICU follow-up should be individualized and based on the patient's comorbidities and severity of illness. Although about 20 medical centers in the United States have post-ICU transition clinics,² there is no evidence that such programs decrease readmission or mortality rates.³

Although the term post-ICU syndrome has been used to describe the various complications reported in ICU survivors (Table 1⁴ ), there is no universally accepted definition for such a syndrome. Family physicians must be familiar with the complications that can occur after discharge (e.g., physical and psychological impairments), including in patients recovering from COVID-19.

Physical Considerations

DECONDITIONING

One year after ICU discharge, more than 20% of patients without functional limitations before admission experience some difficulty in completing activities of daily living.⁵ The National Institute for Health and Care Excellence recommends reassessing patients' physical function two to three months following discharge.⁶ Exercise and self-help rehabilitation programs improve muscle function and cardiopulmonary function after critical illness.^7,8 Patients with deconditioning should be instructed on starting a home exercise regimen or referred to physical therapy.

In general, patients should be screened for weakness at follow-up and referred for physical rehabilitation when appropriate.^5–8

CRITICAL ILLNESS POLYNEUROPATHY

Patients treated in the ICU are at risk of critical illness (or ICU-acquired) polyneuropathy, a disease of the peripheral nerves secondary to axonal degeneration. This condition is caused by complex and poorly understood processes that include microcirculatory abnormalities, metabolic derangements, and other factors.^9–11 Critical illness polyneuropathy is diagnosed by the presence of limb weakness and unexplained difficulty in weaning from mechanical ventilation. Sepsis, prolonged mechanical ventilation, hyperglycemia, and multiorgan failure increase the risk of critical illness polyneuropathy.^9,10

Although nerve function usually begins to improve when major medical issues are resolved, weakness and numbness may persist in severe cases. There is little evidence for physical rehabilitation or pharmacologic interventions in the treatment of critical illness polyneuropathy, but early mobilization in the ICU may improve mobility and muscle strength. ^12,13 For painful polyneuropathy, gabapentin (Neurontin), pregabalin (Lyrica), or serotonin-norepinephrine reuptake inhibitors should be considered.

CRITICAL ILLNESS MYOPATHY

Critical illness (or ICU-acquired) myopathy also presents as muscle weakness and difficulty weaning from mechanical ventilation. The pathophysiology of critical illness myopathy is believed to be similar to that of critical illness polyneuropathy.^10,11 Electromyography and nerve conduction velocity studies can assist with distinguishing between these two clinically similar diseases. Muscle biopsy is considered the diagnostic standard for critical illness myopathy.¹² Unlike critical illness polyneuropathy, critical illness myopathy may improve with exercise. Early mobilization and physical therapy have the greatest evidence of benefit.^10,11