The Pressure Paradox: Abdominal Compression to Detect Lung Hyperinflation in COVID-19 Acute Respiratory Distress Syndrome
Bibliographic record
Abstract
A 57-year-old male with respiratory failure secondary to coronavirus disease (COVID-19) pneumonia was intubated for worsening hypoxemia 22 days after onset of symptoms. Past medical history was significant for type 2 diabetes mellitus, hypertension, mild asthma, distal pancreatectomy in the context of severe necrotizing pancreatitis (2003), small hiatal hernia, and 20-pack-year smoking. His body mass index was 20.7 kg/m2. He was ventilated with ultraprotective volume-control ventilation (Vt of 4.5 ml/kg predicted body weight) and, owing to lack of recruitability as assessed by the recruitment-to-inflation ratio (0.2) (1), positive end-expiratory pressure (PEEP) of 6 cm H2O. Chest radiography demonstrated dense bilateral consolidations to the lower lobes and periphery of the mid-lung zones associated with mild to moderate interstitial edema and pulmonary vascular prominence. A computed tomographic scan confirmed bilateral widespread subpleural consolidations associated with patchy peripheral ground-glass opacities with areas of lobular sparing. On Day 4 after intubation, while the patient was sedated and paralyzed, and in supine semirecumbent position, we noticed that a moderate sustained manual compression at the level of the patient’s mesogastrium was associated with a paradoxical and almost immediate drop in both peak and plateau pressures that persisted for the entire duration of abdominal compression (see Figure 1 and Video 1) (2). Pressure values returned to baseline as soon as compression was released. This phenomenon was reproducible over the course of several days. Ventilator screenshots demonstrating the effect of a moderate sustained manual abdominal compression and its release on airway pressures and respiratory mechanics in a sedated and paralyzed patient with severe respiratory failure secondary to coronavirus disease (COVID-19) infection. The red rectangles represent enlargement of the pressure–time curve profiles. A reduction of the pressure over time concavity during abdominal compression, suggesting reduction in tidal hyperinflation, can be seen. The measured quasistatic (3) airway and static esophageal and bladder pressures (and their derived parameters of lung and chest wall respiratory mechanics; https://rtmaven.com) are shown in Table 1 and Video 1. Visual observation of pressure–time curve profiles revealed a reduction of the pressure over time concavity during abdominal compression (see Figure 1 and Video 1) (2). This observation suggests that the pressure applied to the patient’s abdomen, by increasing intrathoracic pressure, caused a reduction in the end-expiratory lung volume and a downward shift of the pressure–volume curve, with reduction in tidal hyperinflation and possibly increase in tidal recruitment. The combination of these two effects led to the paradoxical improvement of lung and respiratory system compliance, and of lung stress (4, 5). Measured Airway, Esophageal, and Bladder Pressures, and Derived Lung and Chest Wall Respiratory Mechanics Parameters Since our original observation in June 2020, we and other groups (5) have identified several patients with severe COVID-19 acute respiratory distress syndrome displaying similar paradoxical improvements of respiratory mechanics during abdominal compression. Such a simple bedside maneuver can detect lung hyperinflation even in patients mechanically ventilated with ultraprotective lung strategies and low PEEP. Video demonstrating the paradoxical effect of a moderate sustained manual abdominal compression and its release on airway pressures and respiratory mechanics in a sedated and paralyzed patient with severe respiratory failure secondary to coronavirus disease (COVID-19) infection. p/t = pressure–time. Originally Published in Press as DOI: 10.1164/rccm.202104-1062IM on November 8, 2021 Author disclosures are available with the text of this article.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.002 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.002 | 0.002 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".