Definition and research guide
This page combines a MeSH definition, publication statistics and selected research abstracts. It is a starting point for reading the literature, not a medical textbook or a systematic evidence review.
Content available: 4 complete abstracts (877 words), 10 references. Full article text is not stored or reproduced here; follow the PMID, DOI or PMC links to read the original sources and their access terms.
Definition
Respiratory muscle contraction during inhalation. The work is accomplished in three phases: lung compliance work, that required to expand the lungs against its elastic forces; tissue resistance work, that required to overcome the viscosity of the lung and chest wall structures; and airway resistance work, that required to overcome airway resistance during the movement of air into the lungs. Work of breathing does not refer to expiration, which is entirely a passive process caused by elastic recoil of the lung and chest cage. (Guyton, Textbook of Medical Physiology, 8th ed, p406)
Definition: NLM Medical Subject Headings (MeSH) scope note (Public domain (U.S. National Library of Medicine); attribution requested). View the MeSH record.
Also known as: Breathing Work; Breathing Works.
Where it fits in the MeSH classification
- Broader topics
- Respiratory Function Tests; Respiratory Physiological Phenomena
Related concepts
- Respiratory Muscle
- Inhalation
- Lung Compliance
- Lung
- Airway Resistance
Research landscape
PubMed indexes 2,163 records tagged with the MeSH heading “Work of Breathing” (counts retrieved 2026-10-31). 140 of them (6.5%) were published from 2020 onward, and the busiest period so far is through 1999 with 1,208 records.
Reviews account for 273 records (12.6%) and meta-analyses for 4. Randomized controlled trials number 179 (8.3%) as a share of all records on the topic. Randomized trials make up a comparatively large share of this literature, which means many treatment questions have been tested directly.
Show the data
| Period | Records |
|---|---|
| through 1999 | 1,208 |
| 2000-2009 | 483 |
| 2010-2019 | 332 |
| 2020 onward | 140 |
Publication-type chart data
| Type | Records | Share |
|---|---|---|
| Reviews | 273 | 12.6% |
| Meta-analyses | 4 | 0.2% |
| Randomized controlled trials | 179 | 8.3% |
Method: PubMed query "Work of Breathing"[MeSH Terms] with publication-type and date filters, retrieved 2026-10-31.
Reading the evidence in anatomy and physiology
Anatomy describes how body structures are built and physiology describes how they normally work, so most findings here are descriptive or mechanistic rather than evidence about treatment. Much of what is known comes from dissection, imaging, tissue studies and experiments in animals, and measurements in healthy volunteers can differ from those in people with disease or at different ages. Normal ranges vary between individuals and populations. Check whether a result was measured in people or in another species, the age and health of the participants, and the method used.
Evidence from open-access studies
These open-access studies come from PubMed’s best-match results for this heading (papers whose main topic it is), ranked here by citation count, with one recent addition. Each abstract is reproduced in full under its recorded open licence so that you can read the authors’ own words. They illustrate the literature; they are not a systematic summary of it. Citation counts measure attention, not reliability or clinical benefit.
Diaphragm ultrasound as indicator of respiratory effort in critically ill patients undergoing assisted mechanical ventilation: a pilot clinical study [1]
Abstract reading summary — source excerpts
- Opening excerpt
- IntroductionPressure-support ventilation, is widely used in critically ill patients; however, the relative contribution of patient's effort during assisted breathing is difficult to measure in clinical conditions.
- Closing excerpt
- 701, p ConclusionsIn patients undergoing in assisted mechanical ventilation, diaphragm thickening is a reliable indicator of respiratory effort, whereas diaphragm excursion should not be used to quantitatively assess diaphragm contractile activity.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (213 words)
IntroductionPressure-support ventilation, is widely used in critically ill patients; however, the relative contribution of patient's effort during assisted breathing is difficult to measure in clinical conditions. Aim of the present study was to evaluate the performance of ultrasonographic indices of diaphragm contractile activity (respiratory excursion and thickening) in comparison to traditional indices of inspiratory muscle effort during assisted mechanical ventilation.MethodConsecutive patients admitted to the ICU after major elective surgery who met criteria for a spontaneous breathing trial with pressure support ventilation were enrolled. Patients with airflow obstruction or after thoracic/gastric/esophageal surgery were excluded. Variable levels of inspiratory muscle effort were achieved by delivery of different levels of ventilatory assistance by random application of pressure support (0, 5 and 15 cmH2O). The right hemidiaphragm was evaluated by B- and M-mode ultrasonography to record respiratory excursion and thickening. Airway, gastric and oesophageal pressures, and airflow were recorded to calculate indices of respiratory effort (diaphragm and esophageal pressure-time product).Results25 patients were enrolled. With increasing levels of pressure support, parallel reductions were found between diaphragm thickening and both diaphragm and esophageal pressure-time product (respectively, R = 0.701, p ConclusionsIn patients undergoing in assisted mechanical ventilation, diaphragm thickening is a reliable indicator of respiratory effort, whereas diaphragm excursion should not be used to quantitatively assess diaphragm contractile activity.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 25886857 · DOI · PMC4403842
A novel non-invasive method to detect excessively high respiratory effort and dynamic transpulmonary driving pressure during mechanical ventilation [2]
Abstract reading summary — source excerpts
- Opening excerpt
- BackgroundExcessive respiratory muscle effort during mechanical ventilation may cause patient self-inflicted lung injury and load-induced diaphragm myotrauma, but there are no non-invasive methods to reliably detect elevated transpulmonary driving pressure and elevated respiratory muscle effort during assisted ventilation.
- Closing excerpt
- Excessive respiratory effort and transpulmonary driving pressure may be frequent in spontaneously breathing ventilated patients.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (251 words)
BackgroundExcessive respiratory muscle effort during mechanical ventilation may cause patient self-inflicted lung injury and load-induced diaphragm myotrauma, but there are no non-invasive methods to reliably detect elevated transpulmonary driving pressure and elevated respiratory muscle effort during assisted ventilation. We hypothesized that the swing in airway pressure generated by respiratory muscle effort under assisted ventilation when the airway is briefly occluded (ΔPocc) could be used as a highly feasible non-invasive technique to screen for these conditions.MethodsRespiratory muscle pressure (Pmus), dynamic transpulmonary driving pressure (ΔPL,dyn, the difference between peak and end-expiratory transpulmonary pressure), and ΔPocc were measured daily in mechanically ventilated patients in two ICUs in Toronto, Canada. A conversion factor to predict ΔPL,dyn and Pmus from ΔPocc was derived and validated using cross-validation. External validity was assessed in an independent cohort (Nanjing, China).ResultsFifty-two daily recordings were collected in 16 patients. In this sample, Pmus and ΔPL were frequently excessively high: Pmus exceeded 10 cm H2O on 84% of study days and ΔPL,dyn exceeded 15 cm H2O on 53% of study days. ΔPocc measurements accurately detected Pmus > 10 cm H2O (AUROC 0.92, 95% CI 0.83-0.97) and ΔPL,dyn > 15 cm H2O (AUROC 0.93, 95% CI 0.86-0.99). In the external validation cohort (n = 12), estimating Pmus and ΔPL,dyn from ΔPocc measurements detected excessively high Pmus and ΔPL,dyn with similar accuracy (AUROC ≥ 0.94).ConclusionsMeasuring ΔPocc enables accurate non-invasive detection of elevated respiratory muscle pressure and transpulmonary driving pressure. Excessive respiratory effort and transpulmonary driving pressure may be frequent in spontaneously breathing ventilated patients.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 31694692 · DOI · PMC6836358
A physiological approach to understand the role of respiratory effort in the progression of lung injury in SARS-CoV-2 infection [3]
Abstract reading summary — source excerpts
- Opening excerpt
- Deterioration of lung function during the first week of COVID-19 has been observed when patients remain with insufficient respiratory support.
- Closing excerpt
- In addition, we discuss the current approach to respiratory support for COVID-19 under this point of view.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (94 words)
Deterioration of lung function during the first week of COVID-19 has been observed when patients remain with insufficient respiratory support. Patient self-inflicted lung injury (P-SILI) is theorized as the responsible, but there is not robust experimental and clinical data to support it. Given the limited understanding of P-SILI, we describe the physiological basis of P-SILI and we show experimental data to comprehend the role of regional strain and heterogeneity in lung injury due to increased work of breathing.In addition, we discuss the current approach to respiratory support for COVID-19 under this point of view.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 32778136 · DOI · PMC7416996
Non-invasive estimation of inspiratory muscle pressure and work of breathing by airway pressure extrapolation from the P0.1 maneuver during assisted ventilation [4]
Abstract reading summary — source excerpts
- Opening excerpt
- Monitoring inspiratory effort during assisted mechanical ventilation is essential to balance lung protection and respiratory muscle loading.
- Closing excerpt
- Derived work of breathing shows good agreement with esophageal pressure-based measurements, supporting the potential of this approach for non-invasive monitoring of inspiratory effort in patients with acute hypoxemic respiratory failure.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (319 words)
Monitoring inspiratory effort during assisted mechanical ventilation is essential to balance lung protection and respiratory muscle loading. Esophageal pressure monitoring remains the reference standard for estimating inspiratory muscle pressure and work of breathing but is invasive and rarely used in routine clinical practice. Non-invasive alternatives based on routinely available ventilator signals are therefore needed. This monocentric physiological substudy of the ICEBERG observational trial included adult patients with acute hypoxemic respiratory failure undergoing assisted mechanical ventilation. Inspiratory muscle pressure (Pmus) was first estimated non-invasively by linear extrapolation of the airway pressure drop recorded during a standardized end-expiratory occlusion (P0.1 maneuver) into early inspiration (up to 500 ms after occlusion). Using the extrapolated Pmus together with airway pressure, airway resistance was calculated during early inspiration, both with and without correction for respiratory system elastance determined by occlusion maneuvers. The resulting resistance and elastance were then used to parameterize the equation of motion of the respiratory system, allowing subsequent reconstruction of the inspiratory Pmus waveform over the entire breath. From the reconstructed pressure signal, peak inspiratory Pmus, work of breathing, and pressure-time product were calculated. Esophageal pressure-derived measurements served as the reference standard, and agreement was assessed using linear regression and Bland-Altman analysis. Eighteen patients (age 67 ± 12 years, PaO₂/FiO₂ 198 ± 44 mmHg) contributed 33 valid measurements. Based on a patient-average analysis, non-invasively estimated Pmus during early inspiration showed statistically significant correlations with esophageal pressure-derived values across all analyzed time points (all p mus showed good agreement with reference measurements (R2 = 0.70; bias = - 0.05 J), whereas pressure-time product exhibited greater bias and wider limits of agreement. A P0.1-guided, non-invasive method based on airway pressure extrapolation allows feasible and physiologically meaningful estimation of inspiratory Pmus during assisted ventilation. Derived work of breathing shows good agreement with esophageal pressure-based measurements, supporting the potential of this approach for non-invasive monitoring of inspiratory effort in patients with acute hypoxemic respiratory failure.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 42463521 · DOI · PMC13377170
Key reviews and meta-analyses
The most cited review-type papers among PubMed’s best-match results for this heading, listed with bibliographic details only. Follow the links for the full text and access terms.
- Research article Patient-ventilator interaction [5]
- Research article Effort to Breathe with Various Spontaneous Breathing Trial Techniques. A Physiologic Meta-analysis [6]
- Research article Pulmonary characteristics in COPD and mechanisms of increased work of breathing [7]
- Research article Work of breathing [8]
- Research article Network of breathing. Multifunctional role of the diaphragm: a review [9]
- Research article Positive expiratory pressure - Common clinical applications and physiological effects [10]
References
- Umbrello M, Formenti P, Longhi D, Galimberti A, Piva I, Pezzi A, et al.. Diaphragm ultrasound as indicator of respiratory effort in critically ill patients undergoing assisted mechanical ventilation: a pilot clinical study. . 2015. PMID 25886857 · DOI · PMC4403842
- Bertoni M, Telias I, Urner M, Long M, Del Sorbo L, Fan E, et al.. A novel non-invasive method to detect excessively high respiratory effort and dynamic transpulmonary driving pressure during mechanical ventilation. . 2019. PMID 31694692 · DOI · PMC6836358
- Cruces P, Retamal J, Hurtado DE, Erranz B, Iturrieta P, González C, et al.. A physiological approach to understand the role of respiratory effort in the progression of lung injury in SARS-CoV-2 infection. . 2020. PMID 32778136 · DOI · PMC7416996
- Behmüller F, Bastian TM, Selpien H, Eimer C, Weiler N, Schädler D, et al.. Non-invasive estimation of inspiratory muscle pressure and work of breathing by airway pressure extrapolation from the P0.1 maneuver during assisted ventilation. . 2026. PMID 42463521 · DOI · PMC13377170
- Tobin MJ, Jubran A, Laghi F. Patient-ventilator interaction. Am J Respir Crit Care Med. 2001. PMID 11316635 · DOI
- Sklar MC, Burns K, Rittayamai N, Lanys A, Rauseo M, Chen L, et al.. Effort to Breathe with Various Spontaneous Breathing Trial Techniques. A Physiologic Meta-analysis. Am J Respir Crit Care Med. 2017. PMID 27768396 · DOI
- Loring SH, Garcia-Jacques M, Malhotra A. Pulmonary characteristics in COPD and mechanisms of increased work of breathing. J Appl Physiol (1985). 2009. PMID 19359620 · DOI · PMC2711781
- Cabello B, Mancebo J. Work of breathing. Intensive Care Med. 2006. PMID 16838150 · DOI
- Kocjan J, Adamek M, Gzik-Zroska B, Czyżewski D, Rydel M. Network of breathing. Multifunctional role of the diaphragm: a review. Adv Respir Med. 2017. PMID 28871591 · DOI
- Fagevik Olsén M, Lannefors L, Westerdahl E. Positive expiratory pressure - Common clinical applications and physiological effects. Respir Med. 2015. PMID 25573419 · DOI
About this article
- Sources
- NLM Medical Subject Headings (definition, synonyms); NCBI PubMed (counts, identifiers); Europe PMC (open-access abstracts and citation counts).
- Verification
- Every reference was resolved against PubMed on 2026-10-31; title, year and DOI matched.
- Review state
- automated source verified; no human expert review has been recorded yet.
- Version
- 1, last updated 2026-10-31.
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Evidence strength
EvidenceHelix's computed view of the study designs behind this topic: how common meta-analyses, randomized trials and reviews are, how recent the literature is, and a plain-language reading. It describes the design mix of the literature. It is not a quality appraisal of any study, and it is not medical advice.