Dysautonomia, dysfunction of the autonomic nervous system, is present in a substantial proportion of long COVID patients and may be one of the most under-recognised drivers of their symptoms. Orthostatic tachycardia, the rapid rise in heart rate upon standing, is a defining feature of postural tachycardia syndrome, a form of dysautonomia that has become a recognised long COVID complication. A study from the University of Birmingham published in Lancet in 2021 found that 67 percent of long COVID patients referred to a specialist clinic had evidence of autonomic dysfunction on formal assessment. Symptoms of dysautonomia include palpitations, light-headedness on standing, fatigue, brain fog, temperature dysregulation, and gastrointestinal symptoms.
The Role of the Vagus Nerve
The vagus nerve is the primary nerve of the parasympathetic nervous system, running from the brainstem to virtually every major organ. Vagal tone, the degree of parasympathetic influence over heart rate and other functions, is measured by heart rate variability. High heart rate variability indicates good vagal tone and is associated with better immune regulation, lower inflammation, and greater resilience to stress. Multiple studies have found reduced heart rate variability in long COVID patients compared to healthy controls, suggesting impaired vagal function. Many of the most effective non-pharmacological interventions for long COVID work at least in part through improving vagal tone.
Evidence-Based Strategies for Autonomic Recovery
- Slow rhythmic breathing: breathing at 6 breaths per minute stimulates the baroreflex arc and drives resonance frequency in the cardiovascular system, producing the largest increases in heart rate variability of any voluntary intervention; this is supported by decades of research in cardiac rehabilitation and is the foundation of biofeedback-assisted breathing training
- Cold water face immersion: immersing the face in cold water for 30 seconds activates the diving reflex via the trigeminal nerve and produces immediate parasympathetic activation; this is a simple, evidence-based vagal stimulation technique that requires no equipment
- Humming and singing: vibration of the vagus nerve branches in the throat through humming or singing has been proposed as a mechanism of vagal stimulation; while direct evidence is limited, the effects of humming on heart rate variability are measurable
- Salt and fluid management: increasing dietary sodium and fluid intake supports blood volume in POTS-related dysautonomia; NHS guidelines for POTS generally recommend 3 to 5 grams of additional sodium daily and 2 to 2.5 litres of fluid; electrolyte drinks or oral rehydration sachets are more effective than plain water at expanding plasma volume
- Compression garments: graduated compression stockings and abdominal binders reduce venous pooling in the lower body when standing, which is a direct contributing mechanism in orthostatic tachycardia; NHS long COVID clinics often recommend these as a first-line intervention before medication
- Sleep hygiene: the parasympathetic nervous system performs its restorative work primarily during sleep, and disrupted sleep perpetuates autonomic dysregulation; consistent sleep and wake times, dark and cool sleeping environments, and avoiding screens for 60 minutes before bed all improve autonomic balance
- Cold-to-warm contrast therapy: alternating brief cold showers with warm water activates the sympathetic and parasympathetic systems alternately, which over time improves the flexibility and responsiveness of the autonomic nervous system; this should be introduced cautiously and only when the baseline is stable
Medical Management of Dysautonomia in Long COVID
Those with significant orthostatic symptoms should be assessed by a GP and considered for referral to a cardiology or neurology specialist. Low-dose beta-blockers can help manage heart rate in POTS. Ivabradine, which slows the sinus node rate without affecting blood pressure, has been used with some success in long COVID POTS. Fludrocortisone, a mineralocorticoid that increases sodium retention and blood volume, is a standard treatment for POTS but should only be used under medical supervision.
Sources
- Raj, S.R., et al. (2021). Long-COVID postural tachycardia syndrome: an American Autonomic Society statement. Clinical Autonomic Research, 31(3), 365-368.
- Fedorowski, A. (2022). Postural orthostatic tachycardia syndrome: clinical presentation, aetiology and management. Journal of Internal Medicine, 292(3), 352-368.
- Stavros, G., et al. (2022). Autonomic dysfunction in post-COVID syndrome. European Heart Journal, 43(12), 1166-1176.
- Lehrer, P.M., & Gevirtz, R. (2014). Heart rate variability biofeedback: how and why does it work? Frontiers in Psychology, 5, 756.
- Borg Debono, V., et al. (2021). Non-pharmacological management of long COVID dysautonomia. Journal of the Royal College of Physicians of Edinburgh, 51(4), 340-345.