Therapeutic benefits of proning to improve pulmonary gas exchange in severe respiratory failure: focus on fundamentals of physiology.

NEW FINDINGS: What is the topic of this review? The use of proning for improving pulmonary gas exchange in critically ill patients. What advances does it highlight? Proning places the lung in its 'natural' posture, and thus optimises the ventilation-perfusion distribution, which enables lung protective ventilation and the alleviation of potentially life-threatening hypoxaemia in COVID-19 and other types of critical illness with respiratory failure. ABSTRACT: The survival benefit of proning patients with acute respiratory distress syndrome (ARDS) is well established and has recently been found to improve pulmonary gas exchange in patients with COVID-19-associated ARDS (CARDS). This review outlines the physiological implications of transitioning from supine to prone on alveolar ventilation-perfusion ( V ̇ A -- Q ̇ ${\dot V_{\rm{A}}}\hbox{--}\dot Q$ ) relationships during spontaneous breathing and during general anaesthesia in the healthy state, as well as during invasive mechanical ventilation in patients with ARDS and CARDS. Spontaneously breathing, awake healthy individuals maintain a small vertical (ventral-to-dorsal) V ̇ A / Q ̇ ${\dot V_{\rm{A}}}/\dot Q$ ratio gradient in the supine position, which is largely neutralised in the prone position, mainly through redistribution of perfusion. In anaesthetised and mechanically ventilated healthy individuals, a vertical V ̇ A / Q ̇ ${\dot V_{\rm{A}}}/\dot Q$ ratio gradient is present in both postures, but with better V ̇ A -- Q ̇ ${\dot V_{\rm{A}}}\hbox{--}\dot Q$ matching in the prone position. In ARDS and CARDS, the vertical V ̇ A / Q ̇ ${\dot V_{\rm{A}}}/\dot Q$ ratio gradient in the supine position becomes larger, with intrapulmonary shunting in gravitationally dependent lung regions due to compression atelectasis of the dorsal lung. This is counteracted by proning, mainly through a more homogeneous distribution of ventilation combined with a largely unaffected high perfusion dorsally, and a consequent substantial improvement in arterial oxygenation. The data regarding proning as a therapy in patients with CARDS is still limited and whether the associated improvement in arterial oxygenation translates to a survival benefit remains unknown. Proning is nonetheless an attractive and lung protective manoeuvre with the potential benefit of improving life-threatening hypoxaemia in patients with ARDS and CARDS.

Exercise-Based Stroke Rehabilitation: Clinical Considerations Following the COVID-19 Pandemic.

Background. The COVID-19 pandemic attributable to the severe acute respiratory syndrome virus (SARS-CoV-2) has had a significant and continuing impact across all areas of healthcare including stroke. Individuals post-stroke are at high risk for infection, disease severity, and mortality after COVID-19 infection. Exercise stroke rehabilitation programs remain critical for individuals recovering from stroke to mitigate risk factors and morbidity associated with the potential long-term consequences of COVID-19. There is currently no exercise rehabilitation guidance for people post-stroke with a history of COVID-19 infection. Purpose. To (1) review the multi-system pathophysiology of COVID-19 related to stroke and exercise; (2) discuss the multi-system benefits of exercise for individuals post-stroke with suspected or confirmed COVID-19 infection; and (3) provide clinical considerations related to COVID-19 for exercise during stroke rehabilitation. This article is intended for healthcare professionals involved in the implementation of exercise rehabilitation for individuals post-stroke who have suspected or confirmed COVID-19 infection and non-infected individuals who want to receive safe exercise rehabilitation. Results. Our clinical considerations integrate pre-COVID-19 stroke (n = 2) and COVID-19 exercise guidelines for non-stroke populations (athletic [n = 6], pulmonary [n = 1], cardiac [n = 2]), COVID-19 pathophysiology literature, considerations of stroke rehabilitation practices, and exercise physiology principles. A clinical decision-making tool for COVID-19 screening and eligibility for stroke exercise rehabilitation is provided, along with key subjective and physiological measures to guide exercise prescription. Conclusion. We propose that this framework promotes safe exercise programming within stroke rehabilitation for COVID-19 and future infectious disease outbreaks.

COVID-19 Pandemic: Clinical Guidance for Aerobic Exercise-Based Stroke Rehabilitation

Objective(s) 1) To discuss the implications of COVID-19 for exercise in the setting of stroke rehabilitation and 2) to guide and inform the clinical implementation of evidence-based aerobic exercise in stroke rehabilitation. Data Sources A literature search was conducted using 4 databases: MEDLINE, EMBASE, PsycINFO, and AMED Allied and Complementary Medicine, from inception to January 27th, 2021. Study Selection We utilized keywords related to COVID-19, exercise, rehabilitation, and included published athletic return to play after COVID-19 infection and clinical practice guidelines on exercise-based recommendations for COVID-19. Out of 391 published articles, none were related to exercise recommendations and stroke rehabilitation in the context of the COVID-19 pandemic. Data Extraction In the absence of stroke-specific guidance, we drew upon pre-COVID clinical practice aerobic exercise guidelines for stroke (n=2) and COVID-19 exercise recommendations for other populations (e.g., athletic [n=6], pulmonary [n=1] and cardiac rehabilitation [n=2]). Data Synthesis Clinical considerations were developed for hospital and out-patient settings to outline safety considerations to reduce the risk of viral transmission and implementation strategies for pre-participation screening, prescription, and progression of aerobic exercise for symptomatic and asymptomatic cases of COVID-19. Based on limited evidence, we suggest that cardiopulmonary exercise stress testing with electrocardiography be conducted following COVID-19 infection and identify subjective and physiological measures to guide decision making regarding the suitability and prescription of aerobic exercise. Finally, we recommend that clinicians and researchers stay abreast with the literature to implement evidence-based practice relating to stroke, aerobic exercise, and COVID-19. Conclusions Using a patient and clinician approach, we have developed COVID-19 specific guidance as a framework for restoring aerobic exercise implementation in stroke rehabilitation settings. Author(s) Disclosures No conflicts of interest.