Comparison of Dynamic Mechanical Power Formula With Geometric Method in Pressure- and Volume-Controlled Ventilation: A Validation Study
NCT ID: NCT07099729
Last Updated: 2025-08-01
Study Results
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Basic Information
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COMPLETED
37 participants
OBSERVATIONAL
2025-04-01
2025-06-01
Brief Summary
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Mechanical power (MP) is a composite parameter that integrates multiple components of ventilator-induced lung injury (VILI) and has shown strong associations with mortality in ARDS. While several formulas exist for calculating MP in VCV and PCV modes, most require inspiratory resistance, which is not readily available at the bedside. The MPdyn formula, introduced by Asar et al., allows for bedside calculation without inspiratory resistance and has shown good agreement with established formulas such as MPrs and MPLM. However, it has never been validated against the geometric method, which calculates mechanical power based on the area of the pressure-volume (P-V) loop and is considered the most accurate standard.
In this single-center study, 37 deeply sedated ARDS patients were ventilated with a Servo-U ventilator using both VCV and PCV modes. For each mode, two different I:E ratios (1:2 and 1:1) were applied, and 12 screenshots of full P-V loops were captured per patient, totaling 444 images. Geometric MP (MPgeo) was calculated using Python-based image processing with OpenCV and NumPy libraries. Dynamic mechanical power (MPdyn) was computed using ventilator-recorded values of minute volume (MVe), work of breathing per liter (WOBv), and PEEP.
The primary outcome was the agreement between MPdyn and MPgeo values under different ventilator modes and I:E ratios. Secondary outcomes included regression correlation (R²) and Bland-Altman analysis of bias and limits of agreement. This study seeks to determine whether MPdyn is a valid and reliable surrogate for geometric mechanical power, particularly in clinical settings where bedside calculation is needed and inspiratory resistance cannot be easily measured.
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Detailed Description
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Several MP calculation formulas have been proposed for volume-controlled ventilation (VCV) and pressure-controlled ventilation (PCV). While formulas such as MPrs (Gattinoni) and MPLM (Trinkle) are widely used, many of them require precise measurement of inspiratory resistance (Raw), which is often not readily accessible at the bedside-especially in PCV. To address this, a dynamic mechanical power formula (MPdyn) was developed by Asar et al., which estimates MP without the need for inspiratory resistance. MPdyn has demonstrated good agreement with MPrs in VCV and with MPLM in PCV. However, it has not been directly validated against the geometric method, which remains the gold standard for MP calculation.
The geometric method involves calculating the area enclosed by the pressure-volume (P-V) loop on the ventilator screen. This area represents the energy per breath, which can be multiplied by respiratory rate to yield MP. Modern ventilators, such as the Maquet Servo-U, provide high-resolution graphical displays that allow for precise area calculations using digital image processing.
This prospective observational study was conducted in the intensive care unit of Bakırköy Dr. Sadi Konuk Training and Research Hospital, Istanbul. A total of 37 ARDS patients who were deeply sedated and under controlled mechanical ventilation were enrolled. Each patient was ventilated in both VCV and PCV modes with two different I:E ratios (1:2 and 1:1). For each setting, three screenshots of the P-V loop were captured, resulting in 12 images per patient and 444 images in total.
Geometric mechanical power (MPgeo) was calculated using Python-based image analysis (OpenCV, NumPy, and PIL libraries). The region of interest (ROI) corresponding to the P-V loop was extracted, binarized, and segmented to compute the loop area. This pixel-based area was then scaled using the known tidal volume (TVe) and pressure (Pinsp) values to obtain mechanical energy per breath. MPgeo was calculated as:
MPgeo (J/min) = \[E\_breath × RR\] + \[PEEP × TVe × RR × 0.098\]
Dynamic mechanical power (MPdyn) was calculated using the following formula:
MPdyn = MVe × \[WOBv + (PEEP × 0.098)\] where MVe is the expiratory minute volume (L/min), WOBv is the work of breathing per liter (J/L), and PEEP is the end-expiratory pressure (cmH₂O).
Statistical analysis included descriptive statistics, Shapiro-Wilk test for normality, univariable linear regression to assess correlation between MPdyn and MPgeo, and Bland-Altman analysis to evaluate agreement between methods. Paired measurements were analyzed both at the patient-averaged level and for all individual data points.
The primary outcome of the study was the degree of agreement between MPdyn and MPgeo under different ventilator modes (VCV, PCV) and I:E ratios (1:1, 1:2). Secondary analyses included evaluating potential biases and limits of agreement.
This study is expected to validate MPdyn as a reliable, practical alternative to geometric calculations in clinical settings, facilitating routine bedside monitoring of mechanical power without requiring complex measurements or advanced equipment.
Conditions
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Study Design
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CASE_CROSSOVER
PROSPECTIVE
Study Groups
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ARDS patients group
This group includes all patients diagnosed with Acute Respiratory Distress Syndrome (ARDS) who underwent both volume-controlled ventilation (VCV) and pressure-controlled ventilation (PCV) modes in a sequential and crossover manner.
Pressure-Controlled Ventilation (PCV) with inspiratory-to-expiratory (I:E) ratio of 1:2.
Patients received pressure-controlled ventilation (PCV) with an I:E ratio of 1:2. Mechanical power was measured using both geometric (MPgeo) and dynamic (MPdyn) methods for validation purposes.
Pressure-Controlled Ventilation (PCV) with inspiratory-to-expiratory (I:E) ratio of 1:1.
Patients received pressure-controlled ventilation (PCV) with an I:E ratio of 1:1. Geometric mechanical power calculations from ventilator screenshots were compared with MPdyn values for accuracy assessment.
Volume-Controlled Ventilation (VCV) with inspiratory-to-expiratory (I:E) ratio of 1:2.
Patients received volume-controlled ventilation (VCV) with an inspiratory-to-expiratory (I:E) ratio of 1:2. Mechanical power was calculated geometrically (MPgeo) using ventilator screenshots, and results were compared with dynamic mechanical power (MPdyn) values.
Volume-Controlled Ventilation (VCV) with inspiratory-to-expiratory (I:E) ratio of 1:1.
Patients received volume-controlled ventilation (VCV) with an inspiratory-to-expiratory (I:E) ratio of 1:1. MPgeo was computed from ventilator screenshots and compared to MPdyn values to assess agreement.
Interventions
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Pressure-Controlled Ventilation (PCV) with inspiratory-to-expiratory (I:E) ratio of 1:2.
Patients received pressure-controlled ventilation (PCV) with an I:E ratio of 1:2. Mechanical power was measured using both geometric (MPgeo) and dynamic (MPdyn) methods for validation purposes.
Pressure-Controlled Ventilation (PCV) with inspiratory-to-expiratory (I:E) ratio of 1:1.
Patients received pressure-controlled ventilation (PCV) with an I:E ratio of 1:1. Geometric mechanical power calculations from ventilator screenshots were compared with MPdyn values for accuracy assessment.
Volume-Controlled Ventilation (VCV) with inspiratory-to-expiratory (I:E) ratio of 1:2.
Patients received volume-controlled ventilation (VCV) with an inspiratory-to-expiratory (I:E) ratio of 1:2. Mechanical power was calculated geometrically (MPgeo) using ventilator screenshots, and results were compared with dynamic mechanical power (MPdyn) values.
Volume-Controlled Ventilation (VCV) with inspiratory-to-expiratory (I:E) ratio of 1:1.
Patients received volume-controlled ventilation (VCV) with an inspiratory-to-expiratory (I:E) ratio of 1:1. MPgeo was computed from ventilator screenshots and compared to MPdyn values to assess agreement.
Eligibility Criteria
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Inclusion Criteria
* Diagnosis of moderate-to-severe ARDS according to the Berlin criteria
* Receiving mechanical ventilation in volume-controlled (VCV) or pressure-controlled (PCV) mode
* Stable hemodynamics during data collection
* Expected to remain under mechanical ventilation for at least 48 hours
* Written informed consent from legal representative
Exclusion Criteria
* Known neuromuscular disease affecting respiratory function
* Pregnancy
* Patients with do-not-resuscitate (DNR) or limitation-of-therapy orders
* Incomplete ventilator data or poor-quality screenshots
18 Years
ALL
No
Sponsors
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Başakşehir Çam & Sakura City Hospital
OTHER_GOV
Responsible Party
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Furkan Tontu
Specialist Doctor
Locations
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Bakirkoy Sadi Konuk Research Hospital
Istanbul, , Turkey (Türkiye)
Countries
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References
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Marini JJ, Rodriguez RM, Lamb V. Bedside estimation of the inspiratory work of breathing during mechanical ventilation. Chest. 1986 Jan;89(1):56-63. doi: 10.1378/chest.89.1.56.
Cabello B, Mancebo J. Work of breathing. Intensive Care Med. 2006 Sep;32(9):1311-4. doi: 10.1007/s00134-006-0278-3. Epub 2006 Jul 13. No abstract available.
ARDS Definition Task Force; Ranieri VM, Rubenfeld GD, Thompson BT, Ferguson ND, Caldwell E, Fan E, Camporota L, Slutsky AS. Acute respiratory distress syndrome: the Berlin Definition. JAMA. 2012 Jun 20;307(23):2526-33. doi: 10.1001/jama.2012.5669.
Acicbe O, Ozgur CY, Rahimi P, Canan E, Asar S, Cukurova Z. The effect of inspiratory rise time on mechanical power calculations in pressure control ventilation: dynamic approach. Intensive Care Med Exp. 2023 Dec 20;11(1):98. doi: 10.1186/s40635-023-00584-6.
Iotti GA, Braschi A, Brunner JX, Smits T, Olivei M, Palo A, Veronesi R. Respiratory mechanics by least squares fitting in mechanically ventilated patients: applications during paralysis and during pressure support ventilation. Intensive Care Med. 1995 May;21(5):406-13. doi: 10.1007/BF01707409.
Asar S, Acicbe O, Sabaz MS, Kucur Tulubas E, Hergunsel GO, Cukurova Z, Canan E, Cakar N. Simplified calculation of mechanical power for pressure controlled ventilation in Covid-19 ARDS patients. Minerva Anestesiol. 2022 Jan-Feb;88(1-2):42-50. doi: 10.23736/S0375-9393.21.15741-4.
van der Meijden S, Molenaar M, Somhorst P, Schoe A. Calculating mechanical power for pressure-controlled ventilation. Intensive Care Med. 2019 Oct;45(10):1495-1497. doi: 10.1007/s00134-019-05698-8. Epub 2019 Jul 29. No abstract available.
Becher T, van der Staay M, Schadler D, Frerichs I, Weiler N. Calculation of mechanical power for pressure-controlled ventilation. Intensive Care Med. 2019 Sep;45(9):1321-1323. doi: 10.1007/s00134-019-05636-8. Epub 2019 May 17. No abstract available.
Chi Y, He H, Long Y. A simple method of mechanical power calculation: using mean airway pressure to replace plateau pressure. J Clin Monit Comput. 2021 Oct;35(5):1139-1147. doi: 10.1007/s10877-020-00575-y. Epub 2020 Aug 11.
Giosa L, Busana M, Pasticci I, Bonifazi M, Macri MM, Romitti F, Vassalli F, Chiumello D, Quintel M, Marini JJ, Gattinoni L. Mechanical power at a glance: a simple surrogate for volume-controlled ventilation. Intensive Care Med Exp. 2019 Nov 27;7(1):61. doi: 10.1186/s40635-019-0276-8.
Asar S, Acicbe O, Cukurova Z, Hergunsel GO, Canan E, Cakar N. Bedside dynamic calculation of mechanical power: A validation study. J Crit Care. 2020 Apr;56:167-170. doi: 10.1016/j.jcrc.2019.12.027. Epub 2020 Jan 2.
Serpa Neto A, Deliberato RO, Johnson AEW, Bos LD, Amorim P, Pereira SM, Cazati DC, Cordioli RL, Correa TD, Pollard TJ, Schettino GPP, Timenetsky KT, Celi LA, Pelosi P, Gama de Abreu M, Schultz MJ; PROVE Network Investigators. Mechanical power of ventilation is associated with mortality in critically ill patients: an analysis of patients in two observational cohorts. Intensive Care Med. 2018 Nov;44(11):1914-1922. doi: 10.1007/s00134-018-5375-6. Epub 2018 Oct 5.
Gattinoni L, Tonetti T, Cressoni M, Cadringher P, Herrmann P, Moerer O, Protti A, Gotti M, Chiurazzi C, Carlesso E, Chiumello D, Quintel M. Ventilator-related causes of lung injury: the mechanical power. Intensive Care Med. 2016 Oct;42(10):1567-1575. doi: 10.1007/s00134-016-4505-2. Epub 2016 Sep 12.
Trinkle CA, Broaddus RN, Sturgill JL, Waters CM, Morris PE. Simple, accurate calculation of mechanical power in pressure controlled ventilation (PCV). Intensive Care Med Exp. 2022 May 30;10(1):22. doi: 10.1186/s40635-022-00448-5.
Other Identifiers
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2025-76
Identifier Type: -
Identifier Source: org_study_id
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