Reply to Tobin et al.: Respiratory Drive Measurements Do Not Signify Conjectural Patient Self-inflicted Lung Injury

Variation in Use of High-Flow Nasal Cannula and Noninvasive Ventilation Among Patients With COVID-19

BACKGROUND

The use of high-flow nasal cannula (HFNC) and noninvasive ventilation (NIV) for hypoxemic respiratory failure secondary to COVID-19 are recommended by critical-care guidelines; however, apprehension about viral particle aerosolization and patient self-inflicted lung injury may have limited use. We aimed to describe hospital variation in the use and clinical outcomes of HFNC and NIV for the management of COVID-19.

METHODS

This was a retrospective observational study of adults hospitalized with COVID-19 who received supplemental oxygen between February 15, 2020, and April 12, 2021, across 102 international and United States hospitals by using the COVID-19 Registry. Associations of HFNC and NIV use with clinical outcomes were evaluated by using multivariable adjusted hierarchical random-effects logistic regression models. Hospital variation was characterized by using intraclass correlation and the median odds ratio.

RESULTS

Among 13,454 adults with COVID-19 who received supplemental oxygen, 8,143 (60%) received nasal cannula/face mask only, 2,859 (21%) received HFNC, 878 (7%) received NIV, 1,574 (12%) received both HFNC and NIV, with 3,640 subjects (27%) progressing to invasive ventilation. The hospital of admission contributed to 24% of the risk-adjusted variation in HFNC and 30% of the risk-adjusted variation in NIV. The median odds ratio for hospital variation of HFNC was 2.6 (95% CI 1.4-4.9) and of NIV was 3.1 (95% CI 1.2-8.1). Among 5,311 subjects who received HFNC and/or NIV, 2,772 (52%) did not receive invasive ventilation and survived to hospital discharge. Hospital-level use of HFNC or NIV were not associated with the rates of invasive ventilation or mortality.

CONCLUSIONS

Hospital variation in the use of HFNC and NIV for acute respiratory failure secondary to COVID-19 was great but was not associated with intubation or mortality. The wide variation and relatively low use of HFNC/NIV observed within our study signaled that implementation of increased HFNC/NIV use in patients with COVID-19 will require changes to current care delivery practices. (ClinicalTrials.gov registration NCT04323787.).

What we learned in the past year in managing our COVID-19 patients in intensive care units?

Coronavirus disease 2019 is a pandemic, was first recognized at Wuhan province, China in December 2019. The disease spread quickly across the globe, spreading stealthily from human to human through both symptomatic and asymptomatic individuals. A multisystem disease which appears to primarily spread via bio aerosols, it has exhibited a wide clinical spectrum involving multiple organ systems with the respiratory system pathology being the prime cause of morbidity and mortality. Initially unleashing a huge destructive trail at Wuhan China, Lombardy Italy and New York City, it has now spread to all parts of the globe and has actively thrived and mutated into new forms. Health care systems and Governments responded initially with panic, with containment measures giving way to mitigation strategies. The global medical and scientific community has come together and responded to this huge challenge. Professional medical societies quickly laid out "expert" guidelines which were conservative in their approach. Many drugs were re formulated and tested quickly with the help of national and international collaborative groups, helping carve out effective treatment strategies and help build a good scientific foundation for evidence-based medicine. Out of the darkness of chaos, we now have an orderly approach to manage this disease both from a public health preventive and therapeutic standpoint. With preventive measures such as masking and social distancing to the development of highly effective and potent vaccines, the public health success of such measures has been tempered by behavioral responses and resource mobilization. From a therapy standpoint, we now have drugs that were promising but now proven ineffective, and those that are effective when given early during viral pathogenesis or later when immune dysregulation has established, and the goal is to help reign in the destructive cascade. It has been a fascinating journey for mankind and our work here recapitulates the evolution of various aspects of critical care and other inpatient practices which continue to evolve.

Breath-holding as a novel approach to risk stratification in COVID-19

BACKGROUND

Despite considerable progress, it remains unclear why some patients admitted for COVID-19 develop adverse outcomes while others recover spontaneously. Clues may lie with the predisposition to hypoxemia or unexpected absence of dyspnea ('silent hypoxemia') in some patients who later develop respiratory failure. Using a recently-validated breath-holding technique, we sought to test the hypothesis that gas exchange and ventilatory control deficits observed at admission are associated with subsequent adverse COVID-19 outcomes (composite primary outcome: non-invasive ventilatory support, intensive care admission, or death).

METHODS

Patients with COVID-19 (N = 50) performed breath-holds to obtain measurements reflecting the predisposition to oxygen desaturation (mean desaturation after 20-s) and reduced chemosensitivity to hypoxic-hypercapnia (including maximal breath-hold duration). Associations with the primary composite outcome were modeled adjusting for baseline oxygen saturation, obesity, sex, age, and prior cardiovascular disease. Healthy controls (N = 23) provided a normative comparison.

RESULTS

The adverse composite outcome (observed in N = 11/50) was associated with breath-holding measures at admission (likelihood ratio test, p = 0.020); specifically, greater mean desaturation (12-fold greater odds of adverse composite outcome with 4% compared with 2% desaturation, p = 0.002) and greater maximal breath-holding duration (2.7-fold greater odds per 10-s increase, p = 0.036). COVID-19 patients who did not develop the adverse composite outcome had similar mean desaturation to healthy controls.

CONCLUSIONS

Breath-holding offers a novel method to identify patients with high risk of respiratory failure in COVID-19. Greater breath-hold induced desaturation (gas exchange deficit) and greater breath-holding tolerance (ventilatory control deficit) may be independent harbingers of progression to severe disease.