Lec 13 Multisystem Respiratory Conditions: COVID-19 and POTS Study Guide

Fundamentals of Multisystem Respiratory Conditions

• Definition: Multisystem respiratory conditions are complex disorders characterized by lung pathology that is intrinsically linked to damage, inflammation, or dysfunction in other major organ systems.

• Organ-System Axes: These diseases involve complex interactions including:

  • Heart-lung axis.

  • Kidney-lung axis.

  • Brain-lung axis.

  • Neuro-lung axis.

• Pathophysiological Impact: These interactions lead to inflammatory reactions, hypoxia, and metabolic disturbances, which profoundly impact a patient's overall health and prognosis.

COVID-19: Acute Pathology and Impacts

• Etiology: Respiratory disease caused by Severe Acute Respiratory Syndrome Coronavirus 2 ($SARS-CoV-2$).

• Clinical Presentation Categories:

  • Asymptomatic COVID-19: Observed in approximately $40\%$ of healthy individuals who test positive. While they exhibit no noticeable symptoms, recovery may still show lung damage, predisposing them to future health issues.

  • Symptomatic COVID-19: Ranges from very mild (barely noticeable) to mild (weak) or moderate (pronounced but manageable).

  • Severe/Critical: Involves significant respiratory failure and multiorgan impact.

• Lung Pathology Findings (Post-Mortem):

• Early evidence indicates that lung damage occurs in approximately 20% of patients discharged from hospital

  • Extensive alveolar damage.

  • Capillary congestion.

  • Necrosis of pneumocytes.

  • Interstitial and alveolar oedema (fluid in air spaces).

• Acute Respiratory Distress Syndrome (ARDS): A lung disease triggered by COVID-19 where lungs fill with fluid, making breathing impossible and causing oxygen levels to plunge. The primary treatment is time, involving artificial ventilation until inflammatory fluid subsides.

• Mechanisms of Lung Damage:

  1. Oxygen enters the lung.

  2. Healthy breathing: Oxygen passes through the air sac (alveoli) into the blood, and oxygenated blood flows to the heart and body.

  3. Breathing with COVID-19: Inflammatory cells pour into the lungs, thickening the membrane and suffocating the alveoli. Oxygen cannot reach the blood, leading to organ failure.

Classification of Disease Severity in Adults

• Mild Illness:

  • No clinical features of moderate or severe disease.

  • Symptoms: Fever, cough, sore throat, malaise, headache, muscle pain, nausea, vomiting, diarrhoea, loss of taste/smell.

  • No new shortness of breath or difficulty breathing on exertion.

  • No evidence of lower respiratory tract disease on imaging.

• Moderate Illness:

  • Stable patient with evidence of lower respiratory tract disease.

  • Oxygen saturation ($SpO_2$) between $92-94\%$ on room air at rest.

  • Desaturation or breathlessness with mild exertion.

• Severe Illness:

  • Patient with signs of moderate disease who is deteriorating OR meeting any of the following:

  • Respiratory rate $\geq 30\,\text{breaths/min}$.

  • Oxygen saturation ($SpO_2$) < 92\% on room air at rest or requiring oxygen.

  • Lung infiltrates > 50\%.

• Critical Illness:

  • Respiratory failure: Severe respiratory failure (PaO_2/FiO_2 < 200), or presence of ARDS.

  • Deterioration despite non-invasive support ($NIV$ or $HFNO$).

  • Requirement for mechanical ventilation.

  • Hypotension, shock, impairment of consciousness, or other organ failure.

Risk Factors for Deterioration and Comorbidities

• Age-Based Risks: Individuals over $65\,\text{years}$ (over $50\,\text{years}$ for Aboriginal and Torres Strait Islander people).

• Demographic/Contextual Factors: Geographical remoteness, socio-economic determinants, and vaccination status (not up-to-date).

• Primary Comorbidities:

  • Respiratory compromise: $COPD$, asthma, bronchiectasis.

  • Cardiovascular disease: Hypertension, ischemic heart disease ($IHD$).

  • Obesity: BMI > 30\,kg/m^2.

  • Diabetes and Renal failure.

  • Immunocompromising conditions: Leukaemias, lymphomas, post-transplant status, high-dose corticosteroids (> 20\,mg prednisone per day for $\geq 14\,\text{days}$).

• NSW Mortality Data (January 2022 - Under 65s):

  • Cardiac disease: $12$

  • Diabetes: $11$

  • Cancer: $10$

  • Chronic lung disease: $9$

  • Obesity: $8$

  • Kidney disease: $8$

  • Liver disease: $5$

  • Asthma: $3$

Long COVID and Post-COVID-19 Condition

• Temporal Definitions:

  • Long COVID: Symptoms continuing $1$ to $3\,\text{months}$ after infection.

  • Post-COVID-19 Condition: Symptoms persisting beyond $12\,\text{weeks}$.

• Physiological Impact: Pulmonary fibrosis (stiffness in lungs) leading to long-term breathlessness. This inflammation and scarring is termed Interstitial Lung Disease ($ILD$).

• Multisystem Symptoms:

  • Neurologic: Cognitive impairment (brain fog), memory loss, headache, sleep dysregulation, olfactory/gustatory dysfunction.

  • Cardiovascular: Myocarditis, heart failure, pericarditis, dysrhythmias, and orthostatic intolerance (e.g., $POTS$).

  • Pulmonary: $ILD$, reactive airway disease.

  • Hematologic: Pulmonary embolism, arterial/venous thromboembolism.

  • Psychiatric: Depression, anxiety, $PTSD$.

• Research Findings on Medium-term Effects (2-3 months post-discharge):

  • Lungs abnormality: $60\%$

  • Heart abnormality: $26\%$

  • Kidney abnormality: $29\%$

  • Fatigue and breathlessness: $55\%$ and $64\%$ respectively.

Assessment and diagnosis of post covis 19 conditions

• Confirm with positive PCR

• Document details of acute illness

• Check current symptoms and ask concerns

Cardiovascular Risks of COVID-19 Antivirals

• Remdesivir:

  • Disrupts viral replication but increases vasodilation of adenosine, inducing catecholamine release. Risks include $VT$, $VF$, $AF$, and

  • When administered intravenously $QT$ prolongation (Torsade de Pointes). Requires continuous heart monitoring.

• Paxlovid:

  • May cause bradycardia and sinus dysfunction. High toxicity risk when combined with tacrolimus; increases bleeding risk with anticoagulants (warfarin); may cause myopathy and skeletal muscle breakdown.

• Ivermectin: Accumulates in the heart and inhibits potassium currents. Requires monitoring for arrhythmias and $QT$ prolongation.

Initial Screening for long covid

• What severity category did the client fall into

  • What symptoms did the client have during infection

  • was the client treated at home

  • if hospitalised, how long for, was the client in ICU, were they on ventilator, did they develop any related disorders or disease

• what population

• does client have any pre-exisiting conditions

• pre existing PA levels

• what is the clients current infection status

• how many days since last day of symptoms

Exercise Rehabilitation for Post-COVID-19 Syndrome

• Risk Stratification (BMJ 2021): Return to exercise only after at least $7\,\text{days}$ symptom-free. If the patient had severe illness or cardiac symptoms (chest pain, palpitations), a cardiology opinion is required.

• The Phased Return to Physical Activity:

  • Phase 1 ($RPE\,6-8$): Preparation; deep breathing, stretching, balance, gentle walking.

  • Phase 2 ($RPE\,6-11$): Low intensity; yoga, light garden tasks. Graduate by $10-15\,\text{mins/day}$.

  • Phase 3 ($RPE\,12-14$): Moderate intensity aerobic/strength; 2 intervals of $5\,\text{minutes}$ aerobic activity.

  • Phase 4 ($RPE\,12-14$): Coordination and functional skills; $2:1$ training to recovery day ratio.

  • Phase 5 (RPE > 15): Baseline exercise; return to regular exercise pattern.

• Johns Hopkins Phases:

  • Beginning: Deep breathing (back/stomach), eye nods, bed rolling, seated cross-crawl.

  • Building: Deep breathing (sitting/standing), head rotations, rocking to stand, bird-dog, bicep curls ($5-10\,\text{min}$ cardio).

  • Being: Standing deep breathing, mini squats, wall push-ups ($30-45\,\text{min}$ cardio).

Postural Orthostatic Tachycardia Syndrome (POTS)

• Definition: A clinical syndrome lasting at least $6\,\text{months}$ involving the Autonomic Nervous System ($ANS$).

  1. Heart Rate ($HR$) increase > 30\,\text{bpm} (> 40\,\text{bpm} for ages $12-19$) within $5-10\,\text{min}$ of quiet standing.

  2. Absence of orthostatic hypotension (> 20\,mmHg drop in $SBP$ or $10\,mmHg$ drop in $DBP$).

• Typical Demographic: Young women (mean age $30.2 \pm 10.3\,\text{years}$; $86\%$ women).

• Symptoms:

  • Heart: Palpitations, chest pain, tachycardia.

  • Neurological: Brain fog, light sensitivity, migraines, tremors.

  • Gastrointestinal: Nausea, bloating, diarrhoea, abdominal pain (often due to decreased $GI$ motility from sympathetic activation).

  • Other: Exercise intolerance, generalized fatigue, temperature disturbances.

• POTS Sub-types:

  • Neuropathic: Decreased sympathetic innervation in legs; blood pooling, blue/warm feet.

  • Hyperadrenergic: Increased noradrenaline and $SBP$; tachycardia, palpitations, tremor.

  • Hypovolemic: Low blood volume (plasma and $RBC$); weakness, low exercise tolerance.

  • Volume Dysregulation: Secondary to impaired $RAAS$ functioning.

Pathophysiology and Mechanisms of POTS

• Deconditioning: Cardiovascular deconditioning characterized by cardiac atrophy and hypovolemia (similar to astronauts post-spaceflight).

• Venous Return Mechanisms:

  • Skeletal Muscle Pump: Limb muscles squeeze veins (e.g., Calf Raises).

  • One-Way Valves: Prevent backflow.

  • Respiratory Pump: Inhalation pressure changes push blood upward.

  • Venomotor Tone: Sympathetic activation constricts veins.

  • Cardiac Suction: Expansion of the right atrium draws blood in.

• Trigger Events: Infection (most common), surgery, concussion, or enforced bedrest.

• Societal Impact in Australia:

  • $800,000$ people living with $POTS$.

  • $70\%$ forced to quit jobs.

  • $7\,\text{years}$ average time for diagnosis.

Management and Exercise in POTS

• Conservative Management:

  • Fluid intake: $2-3\,L/day$.

  • Salt intake: $2-4\,g/day$.

  • Eating: Small, frequent meals.

  • Garments: Compression leggings to aid venous return.

  • Environment: Avoid heat and large alcohol intake.

• Medications:

  • Midodrine (vasoconstrictor).

  • Ivabradine (lowers heart rate).

  • Fludrocortisone (increases blood volume).

  • Propranolol (beta-blocker).

• Exercise Prescription Guidelines:

  • Horizontal Exercise: Start with rowing or recumbent cycling to maximize venous return without orthostatic stress.

  • Heart Rate Control: Keep below sympathetic activation ($120\,bpm$).

  • Resistance Training: Focus on lower limb muscles to enhance the skeletal muscle pump (Leg press, Calf press, Glute bridges).

  • Progression: Gradually add upright exercise as tolerance increases.

  • Efficacy: A $3\,\text{month}$ program ($20-30\,\text{min}$, $3\,\text{times/week}$) can increase heart size and blood volume, with $1$ in $2$ patients no longer fulfilling $POTS$ criteria.

• Complementary Practice: Vagus nerve stimulation via deep breathing, humming, singing, and mindfulness.

Calf raises

avoid deep squats and leg crosses

Eccentric exercises