12/21/2023 0 Comments Zotero pptProlonged bedrest (there have been extensive studies of head-down bedrest simulating chronic weightlessness in astronauts) leads to reduced cardiac output and stroke volume, hypovolaemia, baroreflex impairment, and withdrawal of the sympathetic neural response. ![]() These syndromes may be exacerbated by hypovolaemia resulting from the initial infection or due to deconditioning by bedrest. Very high catecholamine levels can lead to paradoxical vasodilatation, sympathetic activity withdrawal and activation of the vagus nerve resulting in hypotension, dizziness and ultimately syncope. In orthostatic intolerance, the release of epinephrine and norepinephrine causes pronounced tachycardia, which is experienced as palpitations, breathlessness and chest pain (common symptoms of ‘long COVID’). This is then followed by vasoconstriction in the splanchnic vascular bed, which increases venous return to the heart. This results in tachycardia (thus compensating for reduced stroke volume). This is detected by baroreceptors in the heart and aorta, which respond by increasing sympathetic neural and adrenergic tone (mediated by norepinephrine and epinephrine respectively). When a healthy person stands, blood pools in the pelvis and legs, reducing venous return to the heart. The pathophysiology hinges on an abnormal autonomic response to orthostasis (standing up). Orthostatic intolerance syndromes include orthostatic hypotension (OH), vasovagal syncope (VVS) and postural orthostatic tachycardia syndrome (POTS). 7 The popularity and visibility of patient support groups such as (who according to their website have 14,000 subscribers) and the Long COVID SOS group ( ), and the frequent trending of the hashtag #longcovid on Twitter, suggest that patient need is high, and under-recognised by clinicians. 5 Mainstream media are giving publicity to patient-coined terms ‘long COVID’ 6 and ‘long-haul COVID’. 2 Halpin et al reported that after 4–8 weeks, ongoing fatigue is present in more than two thirds, followed by breathlessness and symptoms of post-traumatic stress disorder. ![]() In Italian inpatients, 53% had fatigue, 43% were dyspnoeic and 22% were experiencing chest pain after 2 months. Results of the COVID Symptom Study (based on a smartphone tracker app where users enter their symptoms, which had over 2.8 million recorded users by May 2020) 3,4 are awaited, but smaller studies reveal that protracted symptoms following COVID-19 infection are common. ‘Post-acute COVID’ 1 refers to persistent symptoms 3 weeks after COVID-19 infection, while ‘Chronic COVID’ describes symptoms lasting more than 12 weeks. Following the initial phase, healthcare services are focusing now on controlling new cases and planning rehabilitation strategies. The SARS-CoV-2 (COVID-19) pandemic has caused unprecedented morbidity, mortality and disruption across the world. We present our rationale for an underlying impaired autonomic physiology post-COVID-19 and suggest means of management. ![]() ![]() We suggest that all physicians should be equipped to recognise such cases, appreciate the symptom burden and provide supportive management. We describe a series of individuals with symptoms of ‘long COVID’, and we posit that this condition may be related to a virus- or immune-mediated disruption of the autonomic nervous system resulting in orthostatic intolerance syndromes. It encompasses a plethora of debilitating symptoms (including breathlessness, chest pain, palpitations and orthostatic intolerance) which can last for weeks or more following mild illness. ‘Post-acute COVID’ (known colloquially as ‘long COVID’) is emerging as a prevalent syndrome. Following the initial surge of infections, focus shifted to managing the longer-term sequelae of illness in survivors. The SARS-CoV-2 (COVID-19) pandemic has caused unprecedented morbidity, mortality and global disruption.
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