Atemnot und COVID-19: Ein Aufruf zu mehr Forschung

Atemnot, auch als Dyspnoe bezeichnet, ist ein häufiges und lähmendes Symptom. In mehreren Berichten wurde die Abwesenheit von Atemnot bei einer Untergruppe von Patienten mit COVID-19 hervorgehoben, die manchmal als «stille» oder «glückliche Hypoxie» bezeichnet wird. Ebenfalls wurde in Berichten erwähnt, dass es an einem klaren Zusammenhang zwischen dem klinischen Schweregrad der Erkrankung und der von den Patienten berichteten Schwere der Atemnot fehlt. Die zerebralen Komplikationen von COVID-19 sind weitgehend nachgewiesen, mit einer hohen Prävalenz akuter Enzephalopathien, die möglicherweise die Verarbeitung afferenter Signale oder die absteigende Modulation von Atemnotsignalen beeinträchtigen könnte. In dieser Übersichtsarbeit möchten wir die an der Atemnot beteiligten Mechanismen hervorheben und die Pathophysiologie von COVID-19 und den bekannten Auswirkungen der Erkrankung auf die Interaktion von Gehirn und Lunge zusammenfassen. Anschließend stellen wir Hypothesen für die Veränderung der Wahrnehmung von Atemnot bei COVID-19-Patienten auf und schlagen Möglichkeiten vor, mit denen dieses Phänomen weiter erforscht werden könnte.

Recommended Approaches to Minimize Aerosol Dispersion of SARS-CoV-2 During Noninvasive Ventilatory Support Can Cause Ventilator Performance Deterioration: A Benchmark Comparative Study.

BACKGROUND: SARS-CoV-2 aerosolization during noninvasive positive-pressure ventilation may endanger health care professionals. Various circuit setups have been described to reduce virus aerosolization. However, these setups may alter ventilator performance. RESEARCH QUESTION: What are the consequences of the various suggested circuit setups on ventilator efficacy during CPAP and noninvasive ventilation (NIV)? STUDY DESIGN AND METHODS: Eight circuit setups were evaluated on a bench test model that consisted of a three-dimensional printed head and an artificial lung. Setups included a dual-limb circuit with an oronasal mask, a dual-limb circuit with a helmet interface, a single-limb circuit with a passive exhalation valve, three single-limb circuits with custom-made additional leaks, and two single-limb circuits with active exhalation valves. All setups were evaluated during NIV and CPAP. The following variables were recorded: the inspiratory flow preceding triggering of the ventilator, the inspiratory effort required to trigger the ventilator, the triggering delay, the maximal inspiratory pressure delivered by the ventilator, the tidal volume generated to the artificial lung, the total work of breathing, and the pressure-time product needed to trigger the ventilator. RESULTS: With NIV, the type of circuit setup had a significant impact on inspiratory flow preceding triggering of the ventilator (P < .0001), the inspiratory effort required to trigger the ventilator (P < .0001), the triggering delay (P < .0001), the maximal inspiratory pressure (P < .0001), the tidal volume (P = .0008), the work of breathing (P < .0001), and the pressure-time product needed to trigger the ventilator (P < .0001). Similar differences and consequences were seen with CPAP as well as with the addition of bacterial filters. Best performance was achieved with a dual-limb circuit with an oronasal mask. Worst performance was achieved with a dual-limb circuit with a helmet interface. INTERPRETATION: Ventilator performance is significantly impacted by the circuit setup. A dual-limb circuit with oronasal mask should be used preferentially.

Breathlessness and COVID-19: A Call for Research.

Breathlessness, also known as dyspnoea, is a debilitating and frequent symptom. Several reports have highlighted the lack of dyspnoea in a subgroup of patients suffering from COVID-19, sometimes referred to as "silent" or "happy hyp-oxaemia." Reports have also mentioned the absence of a clear relationship between the clinical severity of the disease and levels of breathlessness reported by patients. The cerebral complications of COVID-19 have been largely demonstrated with a high prevalence of an acute encephalopathy that could possibly affect the processing of afferent signals or top-down modulation of breathlessness signals. In this review, we aim to highlight the mechanisms involved in breathlessness and summarize the pathophysiology of COVID-19 and its known effects on the brain-lung interaction. We then offer hypotheses for the alteration of breathlessness perception in COVID-19 patients and suggest ways of further researching this phenomenon.

Impact of Confinement in Patients under Long-Term Noninvasive Ventilation during the First Wave of the SARS-CoV-2 Pandemic: A Remarkable Resilience.

BACKGROUND: During the first wave of the SARS-CoV-2 pandemic in Switzerland, confinement was imposed to limit transmission and protect vulnerable persons. These measures may have had a negative impact on perceived quality of care and symptoms in patients with chronic disorders. OBJECTIVES: To determine whether patients under long-term home noninvasive ventilation (LTHNIV) for chronic respiratory failure (CRF) were negatively affected by the 56-day confinement (March-April 2020). METHODS: A questionnaire-based survey exploring mood disturbances (HAD), symptom scores related to NIV (S3-NIV), and perception of health-care providers during confinement was sent to all patients under LTHNIV followed up by our center. Symptom scores and data obtained by ventilator software were compared between confinement and the 56 days prior to confinement. RESULTS: Of a total of 100 eligible patients, 66 were included (median age: 66 years [IQR: 53-74]): 35 (53%) with restrictive lung disorders, 20 (30%) with OHS or SRBD, and 11 (17%) with COPD or overlap syndrome. Prevalence of anxiety (n = 7; 11%) and depressive (n = 2; 3%) disorders was remarkably low. Symptom scores were slightly higher during confinement although this difference was not clinically relevant. Technical data regarding ventilation, including compliance, did not change. Patients complained of isolation and lack of social contact. They felt supported by their relatives and caregivers but complained of the lack of regular contact and information by health-care professionals. CONCLUSIONS: Patients under LTHNIV for CRF showed a remarkable resilience during the SARS-CoV-2 confinement period. Comments provided may be helpful for managing similar future health-care crises.

Self-proning in COVID-19 patients on low-flow oxygen therapy: a cluster randomised controlled trial.

RATIONALE AND OBJECTIVES: Prone positioning as a complement to oxygen therapy to treat hypoxaemia in coronavirus disease 2019 (COVID-19) pneumonia in spontaneously breathing patients has been widely adopted, despite a lack of evidence for its benefit. We tested the hypothesis that a simple incentive to self-prone for a maximum of 12 h per day would decrease oxygen needs in patients admitted to the ward for COVID-19 pneumonia on low-flow oxygen therapy. METHODS: 27 patients with confirmed COVID-19 pneumonia admitted to Geneva University Hospitals were included in the study. 10 patients were randomised to self-prone positioning and 17 to usual care. MEASUREMENTS AND MAIN RESULTS: Oxygen needs assessed by oxygen flow on nasal cannula at inclusion were similar between groups. 24 h after starting the intervention, the median (interquartile range (IQR)) oxygen flow was 1.0 (0.1-2.9) L·min-1 in the prone position group and 2.0 (0.5-3.0) L·min-1 in the control group (p=0.507). Median (IQR) oxygen saturation/fraction of inspired oxygen ratio was 390 (300-432) in the prone position group and 336 (294-422) in the control group (p=0.633). One patient from the intervention group who did not self-prone was transferred to the high-dependency unit. Self-prone positioning was easy to implement. The intervention was well tolerated and only mild side-effects were reported. CONCLUSIONS: Self-prone positioning in patients with COVID-19 pneumonia requiring low-flow oxygen therapy resulted in a clinically meaningful reduction of oxygen flow, but without reaching statistical significance.