Long-term outcome of COVID-19 patients treated with helmet noninvasive ventilation vs. high-flow nasal oxygen: a randomized trial.

BACKGROUND: Long-term outcomes of patients treated with helmet noninvasive ventilation (NIV) are unknown: safety concerns regarding the risk of patient self-inflicted lung injury and delayed intubation exist when NIV is applied in hypoxemic patients. We assessed the 6-month outcome of patients who received helmet NIV or high-flow nasal oxygen for COVID-19 hypoxemic respiratory failure. METHODS: In this prespecified analysis of a randomized trial of helmet NIV versus high-flow nasal oxygen (HENIVOT), clinical status, physical performance (6-min-walking-test and 30-s chair stand test), respiratory function and quality of life (EuroQoL five dimensions five levels questionnaire, EuroQoL VAS, SF36 and Post-Traumatic Stress Disorder Checklist for the DSM) were evaluated 6 months after the enrollment. RESULTS: Among 80 patients who were alive, 71 (89%) completed the follow-up: 35 had received helmet NIV, 36 high-flow oxygen. There was no inter-group difference in any item concerning vital signs (N = 4), physical performance (N = 18), respiratory function (N = 27), quality of life (N = 21) and laboratory tests (N = 15). Arthralgia was significantly lower in the helmet group (16% vs. 55%, p = 0.002). Fifty-two percent of patients in helmet group vs. 63% of patients in high-flow group had diffusing capacity of the lungs for carbon monoxide < 80% of predicted (p = 0.44); 13% vs. 22% had forced vital capacity < 80% of predicted (p = 0.51). Both groups reported similar degree of pain (p = 0.81) and anxiety (p = 0.81) at the EQ-5D-5L test; the EQ-VAS score was similar in the two groups (p = 0.27). Compared to patients who successfully avoided invasive mechanical ventilation (54/71, 76%), intubated patients (17/71, 24%) had significantly worse pulmonary function (median diffusing capacity of the lungs for carbon monoxide 66% [Interquartile range: 47-77] of predicted vs. 80% [71-88], p = 0.005) and decreased quality of life (EQ-VAS: 70 [53-70] vs. 80 [70-83], p = 0.01). CONCLUSIONS: In patients with COVID-19 hypoxemic respiratory failure, treatment with helmet NIV or high-flow oxygen yielded similar quality of life and functional outcome at 6 months. The need for invasive mechanical ventilation was associated with worse outcomes. These data indicate that helmet NIV, as applied in the HENIVOT trial, can be safely used in hypoxemic patients. Trial registration Registered on clinicaltrials.gov NCT04502576 on August 6, 2020.

Patient Self-Inflicted Lung Injury-A Narrative Review of Pathophysiology, Early Recognition, and Management Options.

Patient self-inflicted lung injury (P-SILI) is a life-threatening condition arising from excessive respiratory effort and work of breathing in patients with lung injury. The pathophysiology of P-SILI involves factors related to the underlying lung pathology and vigorous respiratory effort. P-SILI might develop both during spontaneous breathing and mechanical ventilation with preserved spontaneous respiratory activity. In spontaneously breathing patients, clinical signs of increased work of breathing and scales developed for early detection of potentially harmful effort might help clinicians prevent unnecessary intubation, while, on the contrary, identifying patients who would benefit from early intubation. In mechanically ventilated patients, several simple non-invasive methods for assessing the inspiratory effort exerted by the respiratory muscles were correlated with respiratory muscle pressure. In patients with signs of injurious respiratory effort, therapy aimed to minimize this problem has been demonstrated to prevent aggravation of lung injury and, therefore, improve the outcome of such patients. In this narrative review, we accumulated the current information on pathophysiology and early detection of vigorous respiratory effort. In addition, we proposed a simple algorithm for prevention and treatment of P-SILI that is easily applicable in clinical practice.

Spontaneous pneumomediastinum in Covid-19 : a case of complete resolution despite invasive positive pressure ventilation

We present the case of a 65-year-old patient who was admitted to the intensive care unit (ICU) due to Covid-19 respiratory failure. During his hospital stay, he developed a spontaneous pneumomediastinum (SP). To date, there have been few reports of SP associated with Covid-19 and even less is known about the impact of positive pressure ventilation on these patients. Our patient was first treated with high-flow nasal cannula oxygen therapy (HFNC). Because of further respiratory deterioration, he was supported with non-invasive ventilation (NIV). Later, he required intubation and ventilation with invasive positive pressure ventilation. Despite this, a complete spontaneous resolution of the pneumomediastinum was observed 13 days after the initial diagnosis. Copyright © Acta Anaesthesiologica Belgica, 2021.

Pneumomediastinum as patient self-inflicted lung injury in patients with acute respiratory distress syndrome due to COVID-19: a case series.

Background: In patients with coronavirus disease (COVID-19) due to severe acute respiratory syndrome coronavirus 2 infection, pneumomediastinum has been increasingly reported in cases of noninvasive oxygen therapy, including high-flow nasal cannula, and invasive mechanical ventilation. However, its pathogenesis is still not understood. Case Presentation: We report two cases of pneumomediastinum in acute respiratory distress syndrome (ARDS) caused by COVID-19. In both cases, control of spontaneous breathing with neuromuscular blocking agents resulted in resolution of pneumoperitoneum. Conclusion: The improvement of pneumomediastinum with control of spontaneous breathing suggested patient self-inflicted lung injury as a possible mechanism in this case series. In ARDS cases with pneumomediastinum, in addition to controlling plateau pressure with conventional lung protective ventilation, spontaneous breathing should be controlled if the patient's inspiratory effort is suspected to be strong.

Simulation to minimise patient self-inflicted lung injury: are we almost there?

Computational modelling has been used to enlighten pathophysiological issues in patients with acute respiratory distress syndrome (ARDS) using a sophisticated, integrated cardiopulmonary model. COVID-19 ARDS is a pathophysiologically distinct entity characterised by dissociation between impairment in gas exchange and respiratory system mechanics, especially in the early stages of ARDS. Weaver and colleagues used computational modelling to elucidate factors contributing to generation of patient self-inflicted lung injury, and evaluated the effects of various spontaneous respiratory efforts with different oxygenation and ventilatory support modes. Their findings indicate that mechanical forces generated in the lung parenchyma are only counterbalanced when the respiratory support mode reduces the intensity of respiratory efforts.

[Treatment recommendations for mechanical ventilation of COVID­19 patients]. / Behandlungsempfehlungen zur Beatmung von COVID­19-Patienten.

Background: Due to the novelty of COVID­19 there is lack of evidence-based recommendations regarding the mechanical ventilation of these patients. Objective: Identification and delineation of critical parameters enabling individualized lung and diaphragm protective mechanical ventilation. Material and methods: Selective literature search, critical evaluation and discussion of expert recommendations. Results: In the current literature a difference between ARDS in COVID­19 and classical ARDS is described; however, there are no evidence-based recommendations for dealing with this discrepancy. In the past parameters and approaches for a personalized mechanical ventilation strategy were already introduced and applied. Conclusion: Using the parameters presented here it is possible to individualize the mechanical ventilation of COVID­19 patients in order to adjust and increase its compatibility to the heterogeneous clinical presentation of the COVID­19 ARDS.

[Development of a giant bulla under spontaneous breathing by self-inflicted lung injury in a patient with COVID-19 pneumonia]. / Entwicklung einer Riesenbulla unter Spontanatmung durch "patient self-inflicted lung injury" bei COVID-19-Pneumonie.

The outbreak of SARS-CoV­2 and the associated COVID-19 pandemic pose major challenges to healthcare systems worldwide. New data on diagnosis, clinical presentation and treatment of the disease are published on a daily basis. This case report describes the fatal course of severe COVID-19 pneumonia in an 81-year-old patient with no previous pulmonary disease who developed a giant bulla during non-invasive high-flow oxygen therapy. Virus-induced diffuse destruction of alveolar tissue or patient self-inflicted lung injury (P-SILI) are discussed as possible pathomechanisms. Future studies must determine whether lung-protective mechanical ventilation with high levels of sedation and paralysis to suppress spontaneous respiratory drive and to reduce transpulmonary pressure can prevent structural lung damage induced both by the virus and P­SILI in COVID-19 patients with ARDS.

Optimising respiratory support for early COVID-19 pneumonia: a computational modelling study.

BACKGROUND: Optimal respiratory support in early COVID-19 pneumonia is controversial and remains unclear. Using computational modelling, we examined whether lung injury might be exacerbated in early COVID-19 by assessing the impact of conventional oxygen therapy (COT), high-flow nasal oxygen therapy (HFNOT), continuous positive airway pressure (CPAP), and noninvasive ventilation (NIV). METHODS: Using an established multi-compartmental cardiopulmonary simulator, we first modelled COT at a fixed FiO2 (0.6) with elevated respiratory effort for 30 min in 120 spontaneously breathing patients, before initiating HFNOT, CPAP, or NIV. Respiratory effort was then reduced progressively over 30-min intervals. Oxygenation, respiratory effort, and lung stress/strain were quantified. Lung-protective mechanical ventilation was also simulated in the same cohort. RESULTS: HFNOT, CPAP, and NIV improved oxygenation compared with conventional therapy, but also initially increased total lung stress and strain. Improved oxygenation with CPAP reduced respiratory effort but lung stress/strain remained elevated for CPAP >5 cm H2O. With reduced respiratory effort, HFNOT maintained better oxygenation and reduced total lung stress, with no increase in total lung strain. Compared with 10 cm H2O PEEP, 4 cm H2O PEEP in NIV reduced total lung stress, but high total lung strain persisted even with less respiratory effort. Lung-protective mechanical ventilation improved oxygenation while minimising lung injury. CONCLUSIONS: The failure of noninvasive ventilatory support to reduce respiratory effort may exacerbate pulmonary injury in patients with early COVID-19 pneumonia. HFNOT reduces lung strain and achieves similar oxygenation to CPAP/NIV. Invasive mechanical ventilation may be less injurious than noninvasive support in patients with high respiratory effort.

Spontaneous pneumomediastinum: A collaborative sequelae between COVID-19 and self-inflicted lung injury - A case report and literature review.

Spontaneous pneumomediastinum is an infrequent complication of COVID-19. The mechanism is still unknown and thought to be related to patient self-inflicted lung injury. Our patient is a 49-year-old male who presented with shortness of breath and cough. A COVID-19 Polymerase Chain Reaction was positive. He required a high-flow nasal cannula, but he did not demand mechanical ventilation. Computed tomography angiography scan of the chest revealed pneumomediastinum. He was managed conservatively, and a complete recovery was achieved. This case highlights the emerging association of COVID-19, patient self-inflicted lung injury, and pneumomediastinum. Furthermore, spontaneous pneumomediastinum should be suspected even in patients who were not mechanically ventilated.

2020 Year in Review: Mechanical Ventilation During the First Year of the COVID-19 Pandemic.

Coronavirus disease 2019 (COVID-19) represents the greatest medical crisis encountered in the young history of critical care and respiratory care. During the early months of the pandemic, when little was known about the virus, the acute hypoxemic respiratory failure it caused did not appear to fit conveniently or consistently into our classification of ARDS. This not only re-ignited a half-century's long simmering debate over taxonomy, but also fueled similar debates over how PEEP and lung-protective ventilation should be titrated, as well as the appropriate role of noninvasive ventilation in ARDS. COVID-19 ignited other debates on emerging concepts such as ARDS phenotypes and patient self-inflicted lung injury from vigorous spontaneous breathing. Over a year later, these early perplexities have receded into the background without having been reviewed or resolved. With a full year of evidence having been published, this narrative review systematically analyzes whether COVID-19-associated respiratory failure is essentially ARDS, with perhaps a somewhat different course of presentation. This includes a review of the severity of hypoxemia and derangements in pulmonary mechanics, PEEP requirements, recruitment potential, ability to achieve lung-protective ventilation goals, duration of mechanical ventilation, associated mortality, and response to noninvasive ventilation. This paper also reviews the concepts of ARDS phenotypes and patient self-inflicted lung injury as these are crucial to understanding the contentious debate over the nature and management of COVID-19.

High risk of patient self-inflicted lung injury in COVID-19 with frequently encountered spontaneous breathing patterns: a computational modelling study.

BACKGROUND: There is on-going controversy regarding the potential for increased respiratory effort to generate patient self-inflicted lung injury (P-SILI) in spontaneously breathing patients with COVID-19 acute hypoxaemic respiratory failure. However, direct clinical evidence linking increased inspiratory effort to lung injury is scarce. We adapted a computational simulator of cardiopulmonary pathophysiology to quantify the mechanical forces that could lead to P-SILI at different levels of respiratory effort. In accordance with recent data, the simulator parameters were manually adjusted to generate a population of 10 patients that recapitulate clinical features exhibited by certain COVID-19 patients, i.e., severe hypoxaemia combined with relatively well-preserved lung mechanics, being treated with supplemental oxygen. RESULTS: Simulations were conducted at tidal volumes (VT) and respiratory rates (RR) of 7 ml/kg and 14 breaths/min (representing normal respiratory effort) and at VT/RR of 7/20, 7/30, 10/14, 10/20 and 10/30 ml/kg / breaths/min. While oxygenation improved with higher respiratory efforts, significant increases in multiple indicators of the potential for lung injury were observed at all higher VT/RR combinations tested. Pleural pressure swing increased from 12.0 ± 0.3 cmH2O at baseline to 33.8 ± 0.4 cmH2O at VT/RR of 7 ml/kg/30 breaths/min and to 46.2 ± 0.5 cmH2O at 10 ml/kg/30 breaths/min. Transpulmonary pressure swing increased from 4.7 ± 0.1 cmH2O at baseline to 17.9 ± 0.3 cmH2O at VT/RR of 7 ml/kg/30 breaths/min and to 24.2 ± 0.3 cmH2O at 10 ml/kg/30 breaths/min. Total lung strain increased from 0.29 ± 0.006 at baseline to 0.65 ± 0.016 at 10 ml/kg/30 breaths/min. Mechanical power increased from 1.6 ± 0.1 J/min at baseline to 12.9 ± 0.2 J/min at VT/RR of 7 ml/kg/30 breaths/min, and to 24.9 ± 0.3 J/min at 10 ml/kg/30 breaths/min. Driving pressure increased from 7.7 ± 0.2 cmH2O at baseline to 19.6 ± 0.2 cmH2O at VT/RR of 7 ml/kg/30 breaths/min, and to 26.9 ± 0.3 cmH2O at 10 ml/kg/30 breaths/min. CONCLUSIONS: Our results suggest that the forces generated by increased inspiratory effort commonly seen in COVID-19 acute hypoxaemic respiratory failure are comparable with those that have been associated with ventilator-induced lung injury during mechanical ventilation. Respiratory efforts in these patients should be carefully monitored and controlled to minimise the risk of lung injury.

Bilateral phrenic nerve block as an effective means of controlling inspiratory efforts in a COVID-19 patient.

Bilateral continuous phrenic nerve block effectively regulates refractory persistent, strong inspiratory effort in a patient with coronavirus disease (COVID-19). A 73-year-old man with acute respiratory distress syndrome (ARDS) due to COVID-19 was admitted to the intensive care unit (ICU). Use of neuromuscular blocking agents (NMBAs) was stopped due to uncontrollable strong inspiratory efforts and worsened lung injury. We performed bilateral continuous phrenic nerve block, which suppressed inspiratory efforts, resulting in lung injury improvement. A bilateral continuous phrenic nerve block is a viable alternative to control refractory strong inspiratory effort leading to lung injury in cases with prolonged NMBA use.

Implications of early respiratory support strategies on disease progression in critical COVID-19: a matched subanalysis of the prospective RISC-19-ICU cohort.

BACKGROUND: Uncertainty about the optimal respiratory support strategies in critically ill COVID-19 patients is widespread. While the risks and benefits of noninvasive techniques versus early invasive mechanical ventilation (IMV) are intensely debated, actual evidence is lacking. We sought to assess the risks and benefits of different respiratory support strategies, employed in intensive care units during the first months of the COVID-19 pandemic on intubation and intensive care unit (ICU) mortality rates. METHODS: Subanalysis of a prospective, multinational registry of critically ill COVID-19 patients. Patients were subclassified into standard oxygen therapy ≥10 L/min (SOT), high-flow oxygen therapy (HFNC), noninvasive positive-pressure ventilation (NIV), and early IMV, according to the respiratory support strategy employed at the day of admission to ICU. Propensity score matching was performed to ensure comparability between groups. RESULTS: Initially, 1421 patients were assessed for possible study inclusion. Of these, 351 patients (85 SOT, 87 HFNC, 87 NIV, and 92 IMV) remained eligible for full analysis after propensity score matching. 55% of patients initially receiving noninvasive respiratory support required IMV. The intubation rate was lower in patients initially ventilated with HFNC and NIV compared to those who received SOT (SOT: 64%, HFNC: 52%, NIV: 49%, p = 0.025). Compared to the other respiratory support strategies, NIV was associated with a higher overall ICU mortality (SOT: 18%, HFNC: 20%, NIV: 37%, IMV: 25%, p = 0.016). CONCLUSION: In this cohort of critically ill patients with COVID-19, a trial of HFNC appeared to be the most balanced initial respiratory support strategy, given the reduced intubation rate and comparable ICU mortality rate. Nonetheless, considering the uncertainty and stress associated with the COVID-19 pandemic, SOT and early IMV represented safe initial respiratory support strategies. The presented findings, in agreement with classic ARDS literature, suggest that NIV should be avoided whenever possible due to the elevated ICU mortality risk.

Usefulness of serial lung ultrasound for a severe COVID-19 patient on extracorporeal membrane oxygenation.

Computed tomography (CT) is the most reliable method to evaluate the progression of COVID-19 pneumonitis. However, in a pandemic, transportation of critically ill invasively ventilated patients to radiology facilities is challenging, especially for those on extracorporeal membrane oxygenation (ECMO). Notably, lung ultrasound (LUS) is a favored alternative imaging modality due to its ease of use at the point of care, which reduces the infectious risk of exposure and transmission; repeatability; absence of radiation exposure; and low cost. We demonstrated that serial LUS compares favorably with other imaging modalities in terms of usefulness for evaluating lung aeration and recovery in an ECMO-managed COVID-19 patient.