The leading comorbid conditions of patients with COVID-19 are hypertension (55%), coronary artery disease and stroke (32%), and diabetes (31%) [10]. Patients with COVID-19 are less likely to have the following chronic illnesses: liver diseases (9%), chronic obstructive pulmonary disease (7%), malignancy (6%), chronic renal failure (4%), gastrointestinal diseases (3%), central nervous system diseases (<1%), and immunodeficiency (1%) [10]. Therefore, survivors requiring prolonged rehabilitation are more likely to be older and to have preexisting cardiovascular and cerebrovascular disease, which may influence their rehabilitation and outcomes.

The most likely early complications are acute respiratory distress syndrome (ARDS) and sepsis/septic shock, multi-organ failure, acute kidney injury, and cardiac injury [2,10,13]. These complications contribute to the need for ICU admissions [10].

Critical illness polyneuropathy (CIP) is a mixed sensorimotor neuropathy that leads to axonal degeneration; it may occur after COVID-19 [5,14-16]. In one study of patients hospitalized in the ICU with ARDS, up to 46% of patients presented with CIP [15]. CIP causes difficulty weaning from mechanical ventilation, generalized and symmetrical weakness (distal greater than proximal, but including diaphragmatic weakness), distal sensory loss, atrophy, and decreased or absent deep tendon reflexes [15,16]. It is associated with pain, loss of range of motion, fatigue, incontinence, dysphagia, anxiety, depression, posttraumatic stress disorder (PTSD), and cognitive loss [15]. Muscle biopsies and electromyographic testing can be diagnostic [15,16]; however, it is unclear how often these tests are performed in acute care settings post–COVID-19.

Critical illness myopathy (CIM), which presents in 48%-96% of ICU patients with ARDS, is a non-necrotizing diffuse myopathy with fatty degeneration, fiber atrophy, and fibrosis [5,15,16]. It is associated with exposure to corticosteroids, paralytics, and sepsis. The clinical presentation is similar to CIP but with more proximal than distal weakness and sensory preservation [15,16]. For both CIP and CIM, the cranial nerves and facial muscles are preserved [16]. Patients recover from myopathy more completely and quickly than from polyneuropathy; however, with both conditions, weakness, loss of function and quality of life, and poor endurance may persist for up to two years or even longer [15,16]. These prolonged changes are out of proportion with any residual loss of pulmonary function. Research studies on the effects of postacute care rehabilitation are inconclusive but suggest that comprehensive integrated inpatient rehabilitation is required [14].

Post–intensive care syndrome is described separately from CIP and CIM; it is associated with reduced pulmonary function (restrictive pattern), reduced inspiratory muscle strength, poor knee extension, poor upper extremity and grip strength, and low functional capacity [17]. Improvement occurs over a year or more [17].

Patients with COVID-19 who have physically recovered and have tested negative for the virus twice are deemed to be cured and noninfectious. However, there are reports of such patients subsequently testing positive 5-13 days later using a different manufacturer’s test kit [18]. The virus may also persist in a patient’s oropharyngeal cavity and stools for up to 15 days after they are declared cured of COVID-19 (no fever, no respiratory symptoms, 2 negative swab tests) [19]. This is of particular concern for patients who are intended to be discharged to rehabilitation facilities or long-term care because they may still be able to transmit disease, potentially infecting other patients or residents. Because of this, an additional 14 days in quarantine or discharge to a dedicated COVID-19 step-down unit has been recommended [18,20].

In one study [13], 20% of hospitalized patients in China with COVID-19 had associated cardiac injury. These patients were more likely to have comorbidities, require mechanical ventilation, and have other complications (eg, ARDS 59%, acute kidney injury 9%, electrolyte disturbances 16%, hypoproteinemia 13% and coagulation disorders 7%) [13]. They also had much higher mortality (51% vs 5%) [13]. The mechanism of cardiac injury is uncertain [13]. Presentations can include arrhythmia, cardiac insufficiency, ejection fraction decline, troponin I elevation, and severe myocarditis with reduced systolic function [4,11]. One brief report profiled a woman with acute myopericarditis/heart failure post–COVID-19 [9]. As the research investigating cardiac injury included either cross-sectional studies or cohort studies with short-term follow-up (4 weeks), long-term outcomes are unknown [4,21]. Persistent tachycardia was common after SARS; however, it tended to resolve itself and was not associated with increased risk of death [4,13]. The presence of cardiac injury and accompanying comorbidities must be taken into consideration for patients entering rehabilitation.

Acutely, 36.4% of patients with COVID-19 develop neurological symptoms, including headaches, disturbed consciousness, seizures, absence of smell and taste, and paresthesia [5,21]. Posterior reversible encephalopathy syndrome, which causes headache, confusion, seizures and visual loss, is a potential complication of COVID-19 [5]. Viral encephalitis has been reported to be caused by COVID-19, and brain tissue edema and partial neuronal degeneration have been found in deceased patients [12,22]. It is hypothesized that COVID-19 can increase one’s risk for acute cerebrovascular events [12]. At least one person has had Guillain-Barré syndrome associated with COVID-19; however, no causal relationship was determined [23].

SARS can induce neurological diseases such as polyneuropathy, viral encephalitis, and aortic ischemic stroke [24]. In MERS, almost one-fifth of patients showed neurological symptoms (altered consciousness, paralysis, ischemic stroke, Guillain-Barré syndrome, infectious neuropathy, or seizures) [25,26].

Patients severely affected by COVID-19 are more likely to have acute kidney injury as well as secondary infection [10,11]. Survivors of ARDS with mechanical ventilation have reported complications such as tracheal stenosis, heterotopic ossification, contractures, adhesive capsulitis, decubitus ulcers, hoarseness, tooth loss, sensorineural hearing loss, tinnitus, brachial plexus injuries, and entrapment neuropathies (peroneal and ulnar) [7,15]. They also had concerns regarding scarring and changes in appearance due to a variety of causes [15].

Osteoporosis and avascular necrosis have been reported as sequelae of SARS [27]. These conditions may have arisen due to the use of corticosteroids, which are not a suggested treatment for COVID-19 [10]. The prevalence of the use of corticosteroids to treat COVID-19 in different cities and countries is unknown.

In one study of patients with respiratory failure or shock, after ICU admission (91% were mechanically ventilated), median global cognition scores (measured by the Repeatable Battery for the Assessment of Neuropsychological Status) were an average of 1.5 SD below the age-adjusted population mean and similar to those of patients with mild cognitive impairment [28]. Among these patients, 26% had scores 2 SD below the population mean, similar to scores for patients with mild Alzheimer disease [28]. Repeat testing at 12 months did not show much change [28]. The trend was the same for patients regardless of their age [15,28]. Cognitive impairment can persist [15,28]. Cognitive impairment can affect 70%-100% of patients at discharge; 46%-80% still have it one year later, and 20% still have it after 5 years [15]. All components of cognition can be affected, including attention, visual-spatial abilities, memory, executive function, and working memory [15,28]. However, there is a great deal of variation in these effects.

In research regarding ICU admissions for ARDS, adverse psychological impacts have been reported [15]. Even after 2 years, PTSD (22%-24%), depression (26%-33%), and general anxiety (38%-44%) are prevalent [15]. These have been reported as concerns post–COVID-19 as well, accompanied by a severe reduction in quality of life and function [7]. One of the greatest risk factors for post-ARDS mood disturbances is premorbid psychiatric illness [15]. Other risks include younger age, female sex, unemployment, alcohol use, and greater use of opioid sedation [15]. Family members may also suffer from PTSD, anxiety, and depression, and they may have difficulty managing their new caregiver roles [15].

These suggestions regarding the design of an inpatient rehabilitation unit in this time of COVID-19, and the procedures to be followed, are mostly based on the experiences of China and Italy, who are ahead of Canada on the COVID-19 trajectory [5,21,29-31]. Experience during the SARS epidemic has also informed these suggestions on the provision of rehabilitative care [32]. Considerations for the design and procedures for inpatient rehabilitation after COVID-19 will become more refined as more survivors are treated and facilities learn from experience. Each suggestion from the literature [5,21,29-31], stated below, needs to be evaluated based on the unique circumstances of each rehabilitation unit as well as the needs of the patients and the greater health care community.

Several suggestions for how allied health care professionals can adapt to working with COVID-19 rehabilitation patients are provided here. These suggestions have been informed by early COVID-19 reports and adapted from acute care guidelines [5,21,30,31].

If patients can be managed at home, this may be a good option, even for patients who might have been admitted to inpatient rehabilitation in the past [29,32]. Isolation is easier at home, and the burden on inpatient services would be lessened [29,32]. However, for this to be a viable choice, enhanced homecare services and outpatient rehabilitation must be available and able to provide a level of care on par with inpatient rehabilitation. This mode of delivery may be difficult to institute if home care staff are restricted from entering patients’ homes [33]. However, given the right precautions, home-based care may be safer for patients who have recovered from COVID-19 and for other patients in a rehabilitation unit [33]. Home-based therapy can be provided over the internet and telephone via telerehabilitation [28]. Both assessment and treatment may be provided, either synchronously (ie, in real time) or asynchronously (eg, a prerecorded customized exercise plan). It is important that processes are put in place to ensure that patients and therapists can use this method successfully, given the rehabilitation needs and comfort with technology of the individual patient. One or more in-person visits may be required as well. Telerehabilitation may also be a good choice for patients being discharged from inpatient rehabilitation to continue their treatment and promote further recovery [30,32].

Recommendations from both China and Italy state that to avoid aggravating respiratory distress or dispersing the virus unnecessarily, respiratory rehabilitation should not begin too early [3,37,38]. In the acute phase, diaphragmatic breathing, pursed lip breathing, bronchial hygiene, lung expansion techniques (positive expiratory pressure), incentive spirometry, manual mobilization of the ribcage, respiratory muscle training, and aerobic exercise are not recommended [37]. Secretions are not commonly a problem after COVID-19; however, comorbid conditions such as bronchiectasis, secondary pneumonia, or aspiration may increase secretions [7]. Postural drainage and standing (for gradually increasing periods of time) are suggested for secretion management [39].

In inpatient rehabilitation, respiratory assessment should include dyspnea, thoracic activity, diaphragmatic activity and amplitude, respiratory muscle strength (maximal inspiratory and expiratory pressures), respiratory pattern, and frequency [38,39]. Cardiac status should also be assessed [39].

In the postacute phase, inspiratory muscle training should be included if inspiratory muscles are weak. Deep, slow breathing, thoracic expansion (with shoulder elevation), diaphragmatic breathing, mobilization of respiratory muscles, airway clearance techniques (as needed), and positive expiratory pressure devices can be added based on assessed needs [38,39]. Care must be taken to avoid overloading the respiratory system and causing distress [7]. One randomized controlled trial showed a significant improvement in respiratory function, endurance, quality of life, and depression from 2 sessions of 10 minutes of respiratory rehabilitation per week for 6 weeks following discharge from acute care [36]. Rehabilitation included respiratory muscle training with a positive expiratory pressure device, cough exercises, diaphragmatic training (using 1 to 3 kilograms of weight on the abdomen in supine), chest stretching, and pursed-lip breathing. Patients should be monitored closely for shortness of breath, decreased SaO₂ (<95%), blood pressure <90/60 or >140/90, heart rate >100 beats per minute, temperature >37.2 ºC, excessive fatigue, chest pain, severe cough, blurred vision, dizziness, heart palpitations, sweating, loss of balance, and headache [3,38].

Functional assessment should include muscle joint range of motion, strength testing, and balance (use of the Berg Balance Scale is suggested) [3,7,38]. Exercise capacity can be assessed with the 6-minute walk test (with continuous oxygen saturation monitoring) and cardiopulmonary exercise testing. Function and disability can be measured with the International Physical Activity Questionnaire, Physical Activity Scale for the Elderly, and the Barthel Index to measure activities of daily living (ADLs).

Physiotherapy should begin in the acute inpatient setting and continue after transfer to inpatient rehabilitation [3,38]. Early mobilization should include frequent posture changes, bed mobility, sit-to-stand, simple bed exercises, and ADLs, while respecting the patient’s respiratory and hemodynamic states [1,7]. Active limb exercises should be accompanied by progressive muscle strengthening (suggested program: 8-12 repetition-maximum load for 8-12 repetitions, 1 to 3 sets with 2 minutes rest between sets, 3 sessions a week for 6 weeks) [3,38]. Neuromuscular electrical stimulation can be used to assist with strengthening. Aerobic reconditioning can be accomplished with overland walking, cycle or arm ergometry, or a NuStep cross trainer [7]. Initially, aerobic activity should be kept to less than 3 metabolic equivalents of task. Later, progressive aerobic exercise should be increased to 20-30 minutes, 3-5 times a week. Balance work should be incorporated. Studies on the effectiveness of exercise interventions after SARS showed benefits for endurance, maximum oxygen consumption, and strength [40].

Occupational therapy should focus on ADL and instrumental ADL guidance as well as targeted interventions to facilitate functional independence and prepare patients for discharge [41]. Speech-language pathologists should assess and treat dysphagia and voice impairments resulting from prolonged intubation and may also address respiratory strength and coordination [41]. Occupational therapists should also address cognitive changes, while speech-language pathologists should address communication issues [41]. Chinese medicine techniques such as tai chi, the Qigong 6-character mnemonic, guided breathing, and Baduanjin qigong have been suggested by the Chinese [3,38]. Education on the importance of a healthy lifestyle and participation in family and social activities should be included. Psychological interventions delivered by occupational therapists, social workers or rehabilitation psychologists may be required for patients with depression, anxiety, or PTSD [41].