Noninvasive respiratory support for acute respiratory failure due to COVID-19

High-flow nasal oxygen versus conventional oxygen therapy and noninvasive ventilation in COVID-19 respiratory failure: a systematic review and network meta-analysis of randomised controlled trials

BACKGROUND

Noninvasive methods of respiratory support, including noninvasive ventilation (NIV), continuous positive airway pressure (CPAP), and high-flow nasal oxygen (HFNO), are potential strategies to prevent progression to requirement for invasive mechanical ventilation in acute hypoxaemic respiratory failure. The COVID-19 pandemic provided an opportunity to understand the utility of noninvasive respiratory support among a homogeneous cohort of patients with contemporary management of acute respiratory distress syndrome. We performed a network meta-analysis of studies evaluating the efficacy of NIV (including CPAP) and HFNO, compared with conventional oxygen therapy (COT), in patients with COVID-19.

METHODS

PubMed, Embase, and the Cochrane library were searched in May 2023. Standard random-effects meta-analysis was used first to estimate all direct pairwise associations and the results from all studies were combined using frequentist network meta-analysis. Primary outcome was treatment failure, defined as discontinuation of HFNO, NIV, or COT despite progressive disease. Secondary outcome was mortality.

RESULTS

We included data from eight RCTs with 2302 patients, (756 [33%] assigned to COT, 371 [16%] to NIV, and 1175 [51%] to HFNO). The odds of treatment failure were similar for NIV (P=0.33) and HFNO (P=0.25), and both were similar to that for COT (reference category). The odds of mortality were similar for all three treatments (odds ratio for NIV vs COT: 1.06 [0.46-2.44] and HFNO vs COT: 0.97 [0.57-1.65]).

CONCLUSIONS

Noninvasive ventilation, high-flow nasal oxygen, and conventional oxygen therapy are comparable with regards to treatment failure and mortality in COVID-19-associated acute respiratory failure.

PROSPERO REGISTRATION

CRD42023426495.

Goals of care and end-of-life communication needs of persons with chronic respiratory disease

PURPOSE OF THE REVIEW

To highlight recent advances in effective communication among persons with chronic respiratory diseases. The authors focus on communication science related to goals of care (GOC) discussions, medical devices, and life-sustaining invasive treatments. The authors discuss important considerations when working with individuals with low literacy and rurality. Communication handoffs between respiratory clinicians and/or palliative care to hospice clinicians are summarized to ensure effective person-centered and caregiver-centered care.

RECENT FINDINGS

Studies suggest the following communication approaches: (1) clarify differences between palliative and end of life; (2) conduct conversations early and gradual throughout the illness trajectory; (3) distinguish types of GOC discussions as they relate to treatment preferences; (4) for patients from rural communities, include family members and spiritual leaders; (5) assess literacy and employ supportive strategies; (6) apply time-limited-trial framework for life-sustaining treatment (LST) decisions; and (7) standardize processes for communication handoffs to hospice clinicians to improve communication fidelity.

SUMMARY

Effective communication tools for clinicians to engage in GOC discussions for persons with chronic respiratory diseases are grounded in a patient-centered framework. A trained clinician should lead these conversations and include interdisciplinary team members throughout the disease trajectory including at the end of life. These approaches may enable patients to express their values and care preferences as they evolve over time.

Effect of Awake Prone Positioning on ROX Index in Critically-ill Patients With Respiratory Failure due to COVID-19

COVID-19 pneumonia causes acute respiratory distress syndrome (ARDS). Prone positioning (PP) is beneficial to pulmonary physiology and improves oxygenation in patients with ARDS. We aimed to investigate the effect of the PP on oxygenation, respiratory rate (RR) and ROX index in non-intubated patients with COVID-19 associated respiratory failure and to determine whether ROX index predicts intubation. Awake critically-ill patients with confirmed diagnosis of COVID-19 who underwent PP were enrolled in the retrospective, single-center study. Oxygenation parameters were recorded 1 h before PP, during PP and 1 h after return to supine position (after PP). Intubation was defined as the endpoint. Seventy-one patients with a median age of 64 [55-73] years were enrolled in the study. PaO2/FiO2 and SpO2/FiO2 improved during PP, this improvement did not persist after PP. RR improved during and after PP in both intubated and non-intubated patients (for all P < .001). ROX index improved only in non-intubated patients (P < .001) but not in intubated patients (P = .07). Area under the curve (AUC) of ROX index for intubation before PP, during PP and after PP were 0.74 [0.61-0.88] (P = .002), 0.76 [0.62-0.91] (P = .001), and 0.76 [0.64-0.89] (P = .001), respectively. ROX index >6.83 before PP had a negative predictive value (NPV) of 0.85; ROX index >8.28 during PP had a NPV of 0.88 and ROX index >7.48 after PP had a NPV of 0.85. In logistic regression adjusted for APACHE II score, ROX index ≤6.83 before PP had an odds ratio (OR) 4.47 [1.39-14.38], ROX index ≤8.28 during PP had an OR 7.96 [2.29-27.64] and ROX index ≤7.48 had an OR 3.98 [1.25-12.61] for prediction of intubation. In conclusion, awake PP improves oxygenation and decreases RR. ROX index improved only in non- intubated patients and a higher ROX index predicts lower risk of progressing to mechanical ventilation with intubation.

[Ventilatory management of SARS-CoV-2 acute respiratory failure]

COVID-19 pneumonia presents several particularities in its clinical presentation (cytokine storm, silent hypoxemia, thrombo-embolic risk) and may lead to a number of acute respiratory distress syndrome (ARDS) phenotypes. While the optimal oxygenation strategy in cases of hypoxemic acute respiratory failure (ARF) is still under debate, ventilatory management of COVID-19-related ARF has confirmed the efficacy of high-flow oxygen therapy and restored interest in other ventilatory approaches such as continuous positive airway pressure (CPAP) and noninvasive ventilation involving a helmet, which due to patient overflow are sometimes implemented outside of critical care units. However, further studies are still needed to determine which patients should be given which oxygenation technique, and under which conditions they require invasive mechanical ventilation, given that delayed initiation potentially burdens prognosis. During invasive mechanical ventilation, ventral decubitus and extracorporeal membrane oxygenation have become increasingly prevalent. While innovative therapies such as awake prone position or lung transplantation have likewise been developed, their indications, modalities and efficacy remain to be determined.

Physiological effects of awake prone position in acute hypoxemic respiratory failure

BACKGROUND

The effects of awake prone position on the breathing pattern of hypoxemic patients need to be better understood. We conducted a crossover trial to assess the physiological effects of awake prone position in patients with acute hypoxemic respiratory failure.

METHODS

Fifteen patients with acute hypoxemic respiratory failure and PaO2/FiO2 < 200 mmHg underwent high-flow nasal oxygen for 1 h in supine position and 2 h in prone position, followed by a final 1-h supine phase. At the end of each study phase, the following parameters were measured: arterial blood gases, inspiratory effort (ΔPES), transpulmonary driving pressure (ΔPL), respiratory rate and esophageal pressure simplified pressure-time product per minute (sPTPES) by esophageal manometry, tidal volume (VT), end-expiratory lung impedance (EELI), lung compliance, airway resistance, time constant, dynamic strain (VT/EELI) and pendelluft extent through electrical impedance tomography.

RESULTS

Compared to supine position, prone position increased PaO2/FiO2 (median [Interquartile range] 104 mmHg [76-129] vs. 74 [69-93], p < 0.001), reduced respiratory rate (24 breaths/min [22-26] vs. 27 [26-30], p = 0.05) and increased ΔPES (12 cmH2O [11-13] vs. 9 [8-12], p = 0.04) with similar sPTPES (131 [75-154] cmH2O s min-1 vs. 105 [81-129], p > 0.99) and ΔPL (9 [7-11] cmH2O vs. 8 [5-9], p = 0.17). Airway resistance and time constant were higher in prone vs. supine position (9 cmH2O s arbitrary units-3 [4-11] vs. 6 [4-9], p = 0.05; 0.53 s [0.32-61] vs. 0.40 [0.37-0.44], p = 0.03). Prone position increased EELI (3887 arbitrary units [3414-8547] vs. 1456 [959-2420], p = 0.002) and promoted VT distribution towards dorsal lung regions without affecting VT size and lung compliance: this generated lower dynamic strain (0.21 [0.16-0.24] vs. 0.38 [0.30-0.49], p = 0.004). The magnitude of pendelluft phenomenon was not different between study phases (55% [7-57] of VT in prone vs. 31% [14-55] in supine position, p > 0.99).

CONCLUSIONS

Prone position improves oxygenation, increases EELI and promotes VT distribution towards dependent lung regions without affecting VT size, ΔPL, lung compliance and pendelluft magnitude. Prone position reduces respiratory rate and increases ΔPES because of positional increases in airway resistance and prolonged expiratory time. Because high ΔPES is the main mechanistic determinant of self-inflicted lung injury, caution may be needed in using awake prone position in patients exhibiting intense ΔPES. Clinical trail registeration: The study was registered on clinicaltrials.gov (NCT03095300) on March 29, 2017.

Factors related to COVID-19 mortality among three Swedish intensive care units-A retrospective study

BACKGROUND

Mortality due to acute hypoxemic respiratory failure (AHRF) in patients with coronavirus disease-19 (COVID-19) differs across units, regions, and countries. These variations may be attributed to several factors, including comorbidities, acute physiological derangement, disease severity, treatment, ethnicity, healthcare system strain, and socioeconomic status. This study aimed to explore the features of patient characteristics, clinical management, and staffing that may be related to mortality among three intensive care units (ICUs) within the same hospital system in South Sweden.

METHODS

We retrospectively analyzed ICU patients with COVID-19 and AHRF in Region Jönköping County, Sweden. The primary outcome was the 90-day mortality rate. We used univariate and multivariable logistic regression analyses to investigate the relationship of predictors with outcomes.

RESULTS

Between March 15, 2020, and May 31, 2021, 331 patients with AHRF and COVID-19 were admitted to the three ICUs. There were differences in disease severity, treatments, process-related factors, and socioeconomic factors between the units. These factors were related to 90-day mortality. After multivariable adjustment, age, severity of acute respiratory distress syndrome, and the number of nurses per ICU-bed independently predicted 90-day mortality.

CONCLUSION

Age, disease severity, and nurse staffing, but not treatment or socioeconomic status, were independently associated with 90-day mortality among critically ill patients with AHRF due to COVID-19. We also identified variations in care related processes, which may be a modifiable risk factor and warrants future investigation.

Barotrauma during Noninvasive Respiratory Support in COVID-19 Pneumonia Outside ICU: The Ancillary COVIMIX-2 Study

BACKGROUND

Noninvasive respiratory support (NIRS) has been extensively used during the COVID-19 surge for patients with acute respiratory failure. However, little data are available about barotrauma during NIRS in patients treated outside the intensive care unit (ICU) setting.

METHODS

COVIMIX-2 was an ancillary analysis of the previous COVIMIX study, a large multicenter observational work investigating the frequencies of barotrauma (i.e., pneumothorax and pneumomediastinum) in adult patients with COVID-19 interstitial pneumonia. Only patients treated with NIRS outside the ICU were considered. Baseline characteristics, clinical and radiological disease severity, type of ventilatory support used, blood tests and mortality were recorded.

RESULTS

In all, 179 patients were included, 60 of them with barotrauma. They were older and had lower BMI than controls (p < 0.001 and p = 0.045, respectively). Cases had higher respiratory rates and lower PaO₂/FiO₂ (p = 0.009 and p < 0.001). The frequency of barotrauma was 0.3% [0.1-1.3%], with older age being a risk factor for barotrauma (OR 1.06, p = 0.015). Alveolar-arterial gradient (A-a) DO₂ was protective against barotrauma (OR 0.92 [0.87-0.99], p = 0.026). Barotrauma required active treatment, with drainage, in only a minority of cases. The type of NIRS was not explicitly related to the development of barotrauma. Still, an escalation of respiratory support from conventional oxygen therapy, high flow nasal cannula to noninvasive respiratory mask was predictive for in-hospital death (OR 15.51, p = 0.001).

CONCLUSIONS

COVIMIX-2 showed a low frequency for barotrauma, around 0.3%. The type of NIRS used seems not to increase this risk. Patients with barotrauma were older, with more severe systemic disease, and showed increased mortality.

Respective Effects of Helmet Pressure Support, Continuous Positive Airway Pressure, and Nasal High-Flow in Hypoxemic Respiratory Failure: A Randomized Crossover Clinical Trial

Rationale: The respective effects of positive end-expiratory pressure (PEEP) and pressure support delivered through the helmet interface in patients with hypoxemia need to be better understood. Objectives: To assess the respective effects of helmet pressure support (noninvasive ventilation [NIV]) and continuous positive airway pressure (CPAP) compared with high-flow nasal oxygen (HFNO) on effort to breathe, lung inflation, and gas exchange in patients with hypoxemia (PaO2/FiO2 ⩽ 200). Methods: Fifteen patients underwent 1-hour phases (constant FiO2) of HFNO (60 L/min), helmet NIV (PEEP = 14 cm H2O, pressure support = 12 cm H2O), and CPAP (PEEP = 14 cm H2O) in randomized sequence. Measurements and Main Results: Inspiratory esophageal (ΔPES) and transpulmonary pressure (ΔPL) swings were used as surrogates for inspiratory effort and lung distension, respectively. Tidal Volume (Vt) and end-expiratory lung volume were assessed with electrical impedance tomography. ΔPES was lower during NIV versus CPAP and HFNO (median [interquartile range], 5 [3-9] cm H2O vs. 13 [10-19] cm H2O vs. 10 [8-13] cm H2O; P = 0.001 and P = 0.01). ΔPL was not statistically different between treatments. PaO2/FiO2 ratio was significantly higher during NIV and CPAP versus HFNO (166 [136-215] and 175 [158-281] vs. 120 [107-149]; P = 0.002 and P = 0.001). NIV and CPAP similarly increased Vt versus HFNO (mean change, 70% [95% confidence interval (CI), 17-122%], P = 0.02; 93% [95% CI, 30-155%], P = 0.002) and end-expiratory lung volume (mean change, 198% [95% CI, 67-330%], P = 0.001; 263% [95% CI, 121-407%], P = 0.001), mostly due to increased aeration/ventilation in dorsal lung regions. During HFNO, 14 of 15 patients had pendelluft involving >10% of Vt; pendelluft was mitigated by CPAP and further by NIV. Conclusions: Compared with HFNO, helmet NIV, but not CPAP, reduced ΔPES. CPAP and NIV similarly increased oxygenation, end-expiratory lung volume, and Vt, without affecting ΔPL. NIV, and to a lesser extent CPAP, mitigated pendelluft. Clinical trial registered with clinicaltrials.gov (NCT04241861).

Helmet CPAP in the emergency department: A narrative review

BACKGROUND

The choice of correct interface for the right patient is crucial for the success of non-invasive ventilation (NIV) therapy. Helmet CPAP is a type of interface used to deliver NIV. Helmet CPAP improves oxygenation by keeping the airway open throughout the breathing cycle with positive end-expiratory pressure (PEEP).

OBJECTIVE

This narrative review describes the technical aspects and clinical indications of helmet continuous positive airway pressure (CPAP). In addition, we explore the advantages and challenges faced using this device at the Emergency Department (ED).

DISCUSSION

Helmet CPAP is tolerable than other NIV interfaces, provides a good seal and has good airway stability. During Covid-19 pandemic, there are evidences it reduced the risk of aerosolization. The potential clinical benefit of helmet CPAP is demonstrated in acute cardiogenic pulmonary oedema (ACPO), Covid-19 pneumonia, immunocompromised patient, acute chest trauma and palliative patient. Compare to conventional oxygen therapy, helmet CPAP had been shown to reduce intubation rate and decrease mortality.

CONCLUSION

Helmet CPAP is one of the potential NIV interface in patients with acute respiratory failure presenting to the emergency department. It is better tolerated for prolonged usage, reduced intubation rate, improved respiratory parameters, and offers protection against aerosolization in infectious diseases.

COVID-19 Lessons Learned: Response to the Anticipated Ventilator Shortage

Early in the COVID-19 pandemic predictions of a worldwide ventilator shortage prompted a worldwide search for solutions. The impetus for the scramble for ventilators was spurred on by inaccurate and often unrealistic predictions of ventilator requirements. Initial efforts looked simply at acquiring as many ventilators as possible from national and international sources. Ventilators from the Strategic National Stockpile were distributed to early hotspots in the Northeast and Northwest United States. In a triumph of emotion over logic, well-intended experts from other industries turned their time, talent, and treasure toward making a ventilator for the first time. Interest in shared ventilation (more than one patient per ventilator) was ignited by an ill-advised video on social media that ignored the principles of gas delivery in deference to social media notoriety. With shared ventilation, a number of groups mistook a physiologic problem for a plumbing problem. The United States government invoked the Defense Production Act to push automotive manufacturers to partner with existing ventilator manufacturers to speed production. The FDA granted emergency use authorization for "splitters" to allow shared ventilation as well as for ventilators and ancillary equipment. Rationing of ventilators was discussed in the lay press and medical literature but was never necessary in the US. Finally, planners realized that staff with expertise in providing mechanical ventilation were the most important shortage. Over 200,000 ventilators were purchased by the United States government, states, cities, health systems, and individuals. Most had little value in caring for patients with COVID-19 ARDS. This paper attempts to look at where miscalculations were made, with an eye toward what we can do better in the future.

Non-invasive ventilation for acute hypoxemic respiratory failure, including COVID-19

Optimal initial non-invasive management of acute hypoxemic respiratory failure (AHRF), of both coronavirus disease 2019 (COVID-19) and non-COVID-19 etiologies, has been the subject of significant discussion. Avoidance of endotracheal intubation reduces related complications, but maintenance of spontaneous breathing with intense respiratory effort may increase risks of patients' self-inflicted lung injury, leading to delayed intubation and worse clinical outcomes. High-flow nasal oxygen is currently recommended as the optimal strategy for AHRF management for its simplicity and beneficial physiological effects. Non-invasive ventilation (NIV), delivered as either pressure support or continuous positive airway pressure via interfaces like face masks and helmets, can improve oxygenation and may be associated with reduced endotracheal intubation rates. However, treatment failure is common and associated with poor outcomes. Expertise and knowledge of the specific features of each interface are necessary to fully exploit their potential benefits and minimize risks. Strict clinical and physiological monitoring is necessary during any treatment to avoid delays in endotracheal intubation and protective ventilation. In this narrative review, we analyze the physiological benefits and risks of spontaneous breathing in AHRF, and the characteristics of tools for delivering NIV. The goal herein is to provide a contemporary, evidence-based overview of this highly relevant topic.

The optimal management of the patient with COVID‐19 pneumonia: HFNC, NIV/CPAP or mechanical ventilation?

The recent pandemic has seen unprecedented demand for respiratory support of patients with COVID‐19 pneumonia, stretching services and clinicians. Yet despite the global numbers of patients treated, guidance is not clear on the correct choice of modality or the timing of escalation of therapy for an individual patient.This narrative review assesses the available literature on the best use of different modalities of respiratory support for an individual patient, and discusses benefits and risks of each, coupled with practical advice to improve outcomes. On current data, in an ideal context, it appears that as disease severity worsens, conventional oxygen therapy is not sufficient alone. In more severe disease, i.e. PaO2/FiO2 ratios below approximately 200, helmet‐CPAP (continuous positive airway pressure) (although not widely available) may be superior to high‐flow nasal cannula (HFNC) therapy or facemask non‐invasive ventilation (NIV)/CPAP, and that facemask NIV/CPAP may be superior to HFNC, but with noted important complications, including risk of pneumothoraces. In an ideal context, invasive mechanical ventilation should not be delayed where indicated and available. Vitally, the choice of respiratory support should not be prescriptive but contextualised to each setting, as supply and demand of resources vary markedly between institutions. Over time, institutions should develop clear policies to guide clinicians before demand exceeds supply, and should frequently review best practice as evidence matures.

Predictors of Noninvasive Respiratory Support Failure in COVID-19 Patients: A Prospective Observational Study

Background and Objective: Respiratory assistance tactic that is best for COVID-19-associated acute hypoxemic respiratory failure (AHRF) individuals has yet to be determined. Patients with AHRF may benefit from the use of a high-flow nasal cannula (HFNC) and non-invasive ventilation (NIV). The goals of this prospective observational research were to estimate predictive factors for HFNC and NIV failure in COVID-19-related AHRF subjects. Materials and Methods: The research enlisted the participation of 124 patients. A stepwise treatment approach was used. HFNC and NIV were used on 124 (100%) and 64 (51.6%) patients, respectively. Thirty (24.2%) of 124 patients were intubated and received invasive mechanical ventilation. Results: 85 (68.5%) patients were managed successfully. Patients who required NIV exhibited a higher prevalence of treatment failure (70.3% vs. 51.6%, p = 0.019) and had higher mortality (59.4% vs. 31.5%, p = 0.001) than patients who received HFNC. Using logistic regression, the respiratory rate oxygenation (ROX) index at 24 h (odds ratio (OR) = 0.74, p = 0.018) and the Charlson Comorbidity Index (CCI) (OR = 1.60, p = 0.003) were found to be predictors of HFNC efficacy. It was the ROX index at 24 h and the CCI optimum cut-off values for HFNC outcome that were 6.1 (area under the curve (AUC) = 0.73) and 2.5 (AUC = 0.68), respectively. Serum ferritin level (OR = 0.23, p = 0.041) and lymphocyte count (OR = 1.03, p = 0.01) were confirmed as predictors of NIV failure. Serum ferritin level at a cut-off value of 456.2 ng/mL (AUC = 0.67) and lymphocyte count lower than 0.70 per mm³, (AUC = 0.70) were associated with NIV failure with 70.5% sensitivity, 68.7% specificity and sensitivity of 84.1%, specificity of 56.2%, respectively. Conclusion: The ROX index at 24 h, CCI, as well as serum ferritin level, and lymphocyte count can be used as markers for HFNC and NIV failure, respectively, in SARS-CoV-2-induced AHRF patients.

Mechanical Ventilation for COVID-19 Patients

Non-invasive ventilation (NIV) or invasive mechanical ventilation (MV) is frequently needed in patients with acute hypoxemic respiratory failure due to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. While NIV can be delivered in hospital wards and nonintensive care environments, intubated patients require intensive care unit (ICU) admission and support. Thus, the lack of ICU beds generated by the pandemic has often forced the use of NIV in severely hypoxemic patients treated outside the ICU. In this context, awake prone positioning has been widely adopted to ameliorate oxygenation during noninvasive respiratory support. Still, the incidence of NIV failure and the role of patient self-induced lung injury on hospital outcomes of COVID-19 subjects need to be elucidated. On the other hand, endotracheal intubation is indicated when gas exchange deterioration, muscular exhaustion, and/or neurological impairment ensue. Yet, the best timing for intubation in COVID-19 is still widely debated, as it is the safest use of neuromuscular blocking agents. Not differently from other types of acute respiratory distress syndrome, the aim of MV during COVID-19 is to provide adequate gas exchange while avoiding ventilator-induced lung injury. At the same time, the use of rescue therapies is advocated when standard care is unable to guarantee sufficient organ support. Nevertheless, the general shortage of health care resources experienced during SARS-CoV-2 pandemic might affect the utilization of high-cost, highly specialized, and long-term supports. In this article, we describe the state-of-the-art of NIV and MV setting and their usage for acute hypoxemic respiratory failure of COVID-19 patients.