Characteristics and determinants of pulmonary long COVID

BACKGROUNDPersistent cough and dyspnea are prominent features of postacute sequelae of SARS-CoV-2 (also termed "long COVID"); however, physiologic measures and clinical features associated with these pulmonary symptoms remain poorly defined. Using longitudinal pulmonary function testing (PFT) and CT imaging, this study aimed to identify the characteristics and determinants of pulmonary long COVID.METHODSThis single-center retrospective study included 1,097 patients with clinically defined long COVID characterized by persistent pulmonary symptoms (dyspnea, cough, and chest discomfort) lasting for 1 or more months after resolution of primary COVID infection.RESULTSAfter exclusion, a total of 929 patients with post-COVID pulmonary symptoms and PFTs were stratified as diffusion impairment and pulmonary restriction, as measured by percentage predicted diffusion capacity for carbon monoxide (DLCO) and total lung capacity (TLC). Longitudinal evaluation revealed diffusion impairment (DLCO ≤ 80%) and pulmonary restriction (TLC ≤ 80%) in 51% of the cohort overall (n = 479). In multivariable modeling regression analysis, invasive mechanical ventilation during primary infection conferred the greatest increased odds of developing pulmonary long COVID with diffusion impairment and restriction (adjusted odds ratio [aOR] = 9.89, 95% CI 3.62-26.9]). Finally, a subanalysis of CT imaging identified radiographic evidence of fibrosis in this patient population.CONCLUSIONLongitudinal PFTs revealed persistent diffusion-impaired restriction as a key feature of pulmonary long COVID. These results emphasize the importance of incorporating PFTs into routine clinical practice for evaluation of long COVID patients with prolonged pulmonary symptoms. Subsequent clinical trials should leverage combined symptomatic and quantitative PFT measurements for more targeted enrollment of pulmonary long COVID patients.FUNDINGNational Institute of Allergy and Infectious Diseases (AI156898, K08AI129705), National Heart, Lung, and Blood Institute (HL153113, OTA21-015E, HL149944), and the COVID-19 Urgent Research Response Fund at the University of Alabama at Birmingham.

Characteristics and Determinants of Pulmonary Long COVID

RATIONALE

Persistent cough and dyspnea are prominent features of post-acute sequelae of SARS-CoV-2 (termed 'Long COVID'); however, physiologic measures and clinical features associated with these pulmonary symptoms remain poorly defined.

OBJECTIVES

Using longitudinal pulmonary function testing (PFTs) and CT imaging, this study aimed to identify the characteristics and determinants of pulmonary Long COVID.

METHODS

The University of Alabama at Birmingham Pulmonary Long COVID cohort was utilized to characterize lung defects in patients with persistent pulmonary symptoms after resolution primary COVID infection. Longitudinal PFTs including total lung capacity (TLC) and diffusion limitation of carbon monoxide (DLCO) were used to evaluate restriction and diffusion impairment over time in this cohort. Analysis of chest CT imaging was used to phenotype the pulmonary Long COVID pathology. Risk factors linked to development of pulmonary Long COVID were estimated using univariate and multivariate logistic regression models.

MEASUREMENTS AND MAIN RESULTS

Longitudinal evaluation 929 patients with post-COVID pulmonary symptoms revealed diffusion impairment (DLCO ≤80%) and restriction (TLC ≤80%) in 51% of the cohort (n=479). In multivariable logistic regression analysis (adjusted odds ratio; aOR, 95% confidence interval [CI]), invasive mechanical ventilation during primary infection conferred the greatest increased odds of developing pulmonary Long COVID with diffusion impaired restriction (aOR=10.9 [4.09-28.6]). Finally, a sub-analysis of CT imaging identified evidence of fibrosis in this population.

CONCLUSIONS

Persistent diffusion impaired restriction was identified as a key feature of pulmonary Long COVID. Subsequent clinical trials should leverage combined symptomatic and quantitative PFT measurements for more targeted enrollment of pulmonary Long COVID patients.

Interferon-dependent signaling is critical for viral clearance in airway neutrophils

Neutrophilic inflammation characterizes several respiratory viral infections, including COVID-19-related acute respiratory distress syndrome, although its contribution to disease pathogenesis remains poorly understood. Blood and airway immune cells from 52 patients with severe COVID-19 were phenotyped by flow cytometry. Samples and clinical data were collected at 2 separate time points to assess changes during ICU stay. Blockade of type I interferon and interferon-induced protein with tetratricopeptide repeats 3 (IFIT3) signaling was performed in vitro to determine their contribution to viral clearance in A2 neutrophils. We identified 2 neutrophil subpopulations (A1 and A2) in the airway compartment, where loss of the A2 subset correlated with increased viral burden and reduced 30-day survival. A2 neutrophils exhibited a discrete antiviral response with an increased interferon signature. Blockade of type I interferon attenuated viral clearance in A2 neutrophils and downregulated IFIT3 and key catabolic genes, demonstrating direct antiviral neutrophil function. Knockdown of IFIT3 in A2 neutrophils led to loss of IRF3 phosphorylation, with consequent reduced viral catabolism, providing the first discrete mechanism to our knowledge of type I interferon signaling in neutrophils. The identification of this neutrophil phenotype and its association with severe COVID-19 outcomes emphasizes its likely importance in other respiratory viral infections and potential for new therapeutic approaches in viral illness.

DirEct versus VIdeo LaryngosCopE (DEVICE): protocol and statistical analysis plan for a randomised clinical trial in critically ill adults undergoing emergency tracheal intubation

INTRODUCTION

Among critically ill patients undergoing orotracheal intubation in the emergency department (ED) or intensive care unit (ICU), failure to visualise the vocal cords and intubate the trachea on the first attempt is associated with an increased risk of complications. Two types of laryngoscopes are commonly available: direct laryngoscopes and video laryngoscopes. For critically ill adults undergoing emergency tracheal intubation, it remains uncertain whether the use of a video laryngoscope increases the incidence of successful intubation on the first attempt compared with the use of a direct laryngoscope.

METHODS AND ANALYSIS

The DirEct versus VIdeo LaryngosCopE (DEVICE) trial is a prospective, multicentre, non-blinded, randomised trial being conducted in 7 EDs and 10 ICUs in the USA. The trial plans to enrol up to 2000 critically ill adults undergoing orotracheal intubation with a laryngoscope. Eligible patients are randomised 1:1 to the use of a video laryngoscope or a direct laryngoscope for the first intubation attempt. The primary outcome is successful intubation on the first attempt. The secondary outcome is the incidence of severe complications between induction and 2 min after intubation, defined as the occurrence of one or more of the following: severe hypoxaemia (lowest oxygen saturation <80%); severe hypotension (systolic blood pressure <65 mm Hg or new or increased vasopressor administration); cardiac arrest or death. Enrolment began on 19 March 2022 and is expected to be completed in 2023.

ETHICS AND DISSEMINATION

The trial protocol was approved with waiver of informed consent by the single institutional review board at Vanderbilt University Medical Center and the Human Research Protection Office of the Department of Defense. The results will be presented at scientific conferences and submitted for publication in a peer-reviewed journal.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov Registry (NCT05239195).

Effect of Fluid Bolus Administration on Cardiovascular Collapse Among Critically Ill Patients Undergoing Tracheal Intubation: A Randomized Clinical Trial

Importance

Hypotension is common during tracheal intubation of critically ill adults and increases the risk of cardiac arrest and death. Whether administering an intravenous fluid bolus to critically ill adults undergoing tracheal intubation prevents severe hypotension, cardiac arrest, or death remains uncertain.

Objective

To determine the effect of fluid bolus administration on the incidence of severe hypotension, cardiac arrest, and death.

Design, Setting, and Participants

This randomized clinical trial enrolled 1067 critically ill adults undergoing tracheal intubation with sedation and positive pressure ventilation at 11 intensive care units in the US between February 1, 2019, and May 24, 2021. The date of final follow-up was June 21, 2021.

Interventions

Patients were randomly assigned to receive either a 500-mL intravenous fluid bolus (n = 538) or no fluid bolus (n = 527).

Main Outcomes and Measures

The primary outcome was cardiovascular collapse (defined as new or increased receipt of vasopressors or a systolic blood pressure <65 mm Hg between induction of anesthesia and 2 minutes after tracheal intubation, or cardiac arrest or death between induction of anesthesia and 1 hour after tracheal intubation). The secondary outcome was the incidence of death prior to day 28, which was censored at hospital discharge.

Results

Among 1067 patients randomized, 1065 (99.8%) completed the trial and were included in the primary analysis (median age, 62 years [IQR, 51-70 years]; 42.1% were women). Cardiovascular collapse occurred in 113 patients (21.0%) in the fluid bolus group and in 96 patients (18.2%) in the no fluid bolus group (absolute difference, 2.8% [95% CI, -2.2% to 7.7%]; P = .25). New or increased receipt of vasopressors occurred in 20.6% of patients in the fluid bolus group compared with 17.6% of patients in the no fluid bolus group, a systolic blood pressure of less than 65 mm Hg occurred in 3.9% vs 4.2%, respectively, cardiac arrest occurred in 1.7% vs 1.5%, and death occurred in 0.7% vs 0.6%. Death prior to day 28 (censored at hospital discharge) occurred in 218 patients (40.5%) in the fluid bolus group compared with 223 patients (42.3%) in the no fluid bolus group (absolute difference, -1.8% [95% CI, -7.9% to 4.3%]; P = .55).

Conclusions and Relevance

Among critically ill adults undergoing tracheal intubation, administration of an intravenous fluid bolus compared with no fluid bolus did not significantly decrease the incidence of cardiovascular collapse.

Trial Registration

ClinicalTrials.gov Identifier: NCT03787732.

Effect of Use of a Bougie vs Endotracheal Tube With Stylet on Successful Intubation on the First Attempt Among Critically Ill Patients Undergoing Tracheal Intubation: A Randomized Clinical Trial

IMPORTANCE

For critically ill adults undergoing emergency tracheal intubation, failure to intubate the trachea on the first attempt occurs in up to 20% of cases and is associated with severe hypoxemia and cardiac arrest. Whether using a tracheal tube introducer ("bougie") increases the likelihood of successful intubation compared with using an endotracheal tube with stylet remains uncertain.

OBJECTIVE

To determine the effect of use of a bougie vs an endotracheal tube with stylet on successful intubation on the first attempt.

DESIGN, SETTING, AND PARTICIPANTS

The Bougie or Stylet in Patients Undergoing Intubation Emergently (BOUGIE) trial was a multicenter, randomized clinical trial among 1102 critically ill adults undergoing tracheal intubation in 7 emergency departments and 8 intensive care units in the US between April 29, 2019, and February 14, 2021; the date of final follow-up was March 14, 2021.

INTERVENTIONS

Patients were randomly assigned to use of a bougie (n = 556) or use of an endotracheal tube with stylet (n = 546).

MAIN OUTCOMES AND MEASURES

The primary outcome was successful intubation on the first attempt. The secondary outcome was the incidence of severe hypoxemia, defined as a peripheral oxygen saturation less than 80%.

RESULTS

Among 1106 patients randomized, 1102 (99.6%) completed the trial and were included in the primary analysis (median age, 58 years; 41.0% women). Successful intubation on the first attempt occurred in 447 patients (80.4%) in the bougie group and 453 patients (83.0%) in the stylet group (absolute risk difference, -2.6 percentage points [95% CI, -7.3 to 2.2]; P = .27). A total of 58 patients (11.0%) in the bougie group experienced severe hypoxemia, compared with 46 patients (8.8%) in the stylet group (absolute risk difference, 2.2 percentage points [95% CI, -1.6 to 6.0]). Esophageal intubation occurred in 4 patients (0.7%) in the bougie group and 5 patients (0.9%) in the stylet group, pneumothorax was present after intubation in 14 patients (2.5%) in the bougie group and 15 patients (2.7%) in the stylet group, and injury to oral, glottic, or thoracic structures occurred in 0 patients in the bougie group and 3 patients (0.5%) in the stylet group.

CONCLUSIONS AND RELEVANCE

Among critically ill adults undergoing tracheal intubation, use of a bougie did not significantly increase the incidence of successful intubation on the first attempt compared with use of an endotracheal tube with stylet.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT03928925

Spatial mapping of SARS-CoV-2 and H1N1 lung injury identifies differential transcriptional signatures

Severe SARS-CoV-2 infection often leads to the development of acute respiratory distress syndrome (ARDS), with profound pulmonary patho-histological changes post-mortem. It is not clear whether ARDS from SARS-CoV-2 is similar to that observed in influenza H1N1, another common viral cause of lung injury. Here, we analyze specific ARDS regions of interest utilizing a spatial transcriptomic platform on autopsy-derived lung tissue from patients with SARS-CoV-2 (n = 3), H1N1 (n = 3), and a dual infected individual (n = 1). Enhanced gene signatures in alveolar epithelium, vascular tissue, and lung macrophages identify not only increased regional coagulopathy but also increased extracellular remodeling, alternative macrophage activation, and squamous metaplasia of type II pneumocytes in SARS-CoV-2. Both the H1N1 and dual-infected transcriptome demonstrated an enhanced antiviral response compared to SARS-CoV-2. Our results uncover regional transcriptional changes related to tissue damage/remodeling, altered cellular phenotype, and vascular injury active in SARS-CoV-2 and present therapeutic targets for COVID-19-related ARDS.

A mechanism for matrikine regulation in acute inflammatory lung injury

Proline-glycine-proline (PGP) and its acetylated form (Ac-PGP) are neutrophil chemoattractants generated by collagen degradation, and they have been shown to play a role in chronic inflammatory disease. However, the mechanism for matrikine regulation in acute inflammation has not been well established. Here, we show that these peptides are actively transported from the lung by the oligopeptide transporter, PEPT2. Following intratracheal instillation of Ac-PGP in a mouse model, there was a rapid decline in concentration of the labeled peptide in the bronchoalveolar lavage (BAL) over time and redistribution to extrapulmonary sites. In vitro knockdown of the PEPT2 transporter in airway epithelia or use of a competitive inhibitor of PEPT2, cefadroxil, significantly reduced uptake of Ac-PGP. Animals that received intratracheal Ac-PGP plus cefadroxil had higher levels of Ac-PGP in BAL and lung tissue. Utilizing an acute LPS-induced lung injury model, we demonstrate that PEPT2 blockade enhanced pulmonary Ac-PGP levels and lung inflammation. We further validated this effect using clinical samples from patients with acute lung injury in coculture with airway epithelia. This is the first study to our knowledge to determine the in vitro and in vivo significance of active matrikine transport as a mechanism of modulating acute inflammation and to demonstrate that it may serve as a potential therapeutic target.

Protocol and statistical analysis plan for the PREventing cardiovascular collaPse with Administration of fluid REsuscitation during Induction and Intubation (PREPARE II) randomised clinical trial

INTRODUCTION

Cardiovascular collapse is a common complication during tracheal intubation of critically ill adults. Whether administration of an intravenous fluid bolus prevents cardiovascular collapse during tracheal intubation remains uncertain. A prior randomised trial found fluid bolus administration to be ineffective overall but suggested potential benefit for patients receiving positive pressure ventilation during tracheal intubation.

METHODS AND ANALYSIS

The PREventing cardiovascular collaPse with Administration of fluid REsuscitation during Induction and Intubation (PREPARE II) trial is a prospective, multi-centre, non-blinded randomised trial being conducted in 13 academic intensive care units in the USA. The trial will randomise 1065 critically ill adults undergoing tracheal intubation with planned use of positive pressure ventilation (non-invasive ventilation or bag-mask ventilation) between induction and laryngoscopy to receive 500 mL of intravenous crystalloid or no intravenous fluid bolus. The primary outcome is cardiovascular collapse, defined as any of: systolic blood pressure <65 mm Hg, new or increased vasopressor administration between induction and 2 min after intubation, or cardiac arrest or death between induction and 1 hour after intubation. The primary analysis will be an unadjusted, intention-to-treat comparison of the primary outcome between patients randomised to fluid bolus administration and patients randomised to no fluid bolus administration using a χ² test. The sole secondary outcome is 28-day in-hospital mortality. Enrolment began on 1 February 2019 and is expected to conclude in June 2020.

ETHICS AND DISSEMINATION

The trial was approved by either the central institutional review board at Vanderbilt University Medical Center or the local institutional review board at each trial site. Results will be submitted for publication in a peer-reviewed journal and presented at scientific conferences.

TRIAL REGISTRATION NUMBER

NCT03787732.

A Longitudinal Curriculum In Point-Of-Care Ultrasonography Improves Medical Knowledge And Psychomotor Skills Among Internal Medicine Residents

PURPOSE

Despite its growing popularity and clinical utility among hospital-based physicians, there are no formal competency requirements nor training standards for United States based Internal Medicine Residencies for learning point-of-care ultrasonography (POCUS). The purpose of this investigation was to study the impact and effectiveness of a novel POCUS curriculum for an Internal Medicine (IM) residency program.

PATIENTS AND METHODS

This was a Single-Group Educational Quasi-Experiment involving Categorical and Preliminary Internal Medicine Residents in Post-Graduate Years 1 through 3 at a single United States academic tertiary center. The study period was from January 1, 2017, through June 30, 2017, during which time the residents participated in monthly modules including didactics and hands-on ultrasound scanning skills with live models. Participants completed a comprehensive knowledge examination at the beginning and end of the six-month period. Participants were also tested regarding hands-on image acquisition and interpretation immediately before and after the hands-on skills labs. The primary outcome measure was performance improvement in a comprehensive medical knowledge assessment.

RESULTS

In total, 42 residents consented for participation. The residents' monthly rotations were adjusted in order to accommodate the new educational process. Among 29 participants with complete data sets for analysis, the mean (SD) comprehensive knowledge examination score improved from 60.9% before curriculum to 70.2% after curriculum completion (P<0.001). Subgroup analysis determined that improvement in medical knowledge required attending at least 2 out of the 6 (33%) educational sessions. Attendance at hands-on skills labs correlated significantly with improvement; didactics alone did not.

CONCLUSION

A longitudinal POCUS curriculum consisting of both didactic sessions and hands-on skills labs improves knowledge, image acquisition, and interpretation skills of residents. Having this curriculum span at least 6 months provides learners the opportunity to attend multiple classes which strengthens learning through repetition while also providing learners flexibility in schedule.