Background: Mechanical power is a summary variable including all the components which can possibly cause VILI (pressures, volume, flow, respiratory rate). Since the complexity of its mathematical computation is one of the major factors that delay its clinical use, we propose here a simple and easy to remember equation to estimate mechanical power under volumecontrolled ventilation:Mechanical Power = VE x (Peak Pressure + PEEP + F/6)/20where the mechanical power is expressed in Joules/minute, the minute ventilation (VE) in liters/minute, the inspiratory flow (F) in liters/minute, and peak pressure and positive endexpiratory pressure (PEEP) in centimeter of water. All the components of this equation are continuously displayed by any ventilator under volumecontrolled ventilation without the need for clinician intervention.To test the accuracy of this new equation, we compared it with the reference formula of mechanical power that we proposed for volumecontrolled ventilation in the past. The comparisons were made in a cohort of mechanically ventilated pigs (485 observations) and in a cohort of ICU patients (265 observations).Results: Both in pigs and in ICU patients, the correlation between our equation and the reference one was close to the identity. Indeed, the R2 ranged from 0.97 to 0.99 and the BlandAltman showed small biases (ranging from + 0.35 to  0.53 J/min) and proportional errors (ranging from + 0.02 to  0.05).Conclusions: Our new equation of mechanical power for volumecontrolled ventilation represents a simple and accurate alternative to the more complex ones available to date. This equation does not need any clinical intervention on the ventilator (such as an inspiratory hold) and could be easily implemented in the software of any ventilator in volumecontrolled mode. This would allow the clinician to have an estimation of mechanical power at a simple glance and thus increase the clinical consciousness of this variable which is still far from being used at the bedside. Our equation carries the same limitations of all other formulas of mechanical power, the most important of which, as far as it concerns VILI prevention, are the lack of normalization and its application to the whole respiratory system (including the chest wall) and not only to the lung parenchyma.
Mechanical power at a glance : a simple surrogate for volumecontrolled ventilation / L. Giosa, M. Busana, I. Pasticci, M. Bonifazi, M.M. Macrì, F. Romitti, F. Vassalli, D. Chiumello, M. Quintel, J.J. Marini, L. Gattinoni.  In: INTENSIVE CARE MEDICINE EXPERIMENTAL.  ISSN 2197425X.  7:1(2019 Nov 27), pp. 61.161.13. [10.1186/s4063501902768]
Mechanical power at a glance : a simple surrogate for volumecontrolled ventilation
M. Busana;I. Pasticci;M. Bonifazi;F. Romitti;D. Chiumello;L. Gattinoni^{}
2019
Abstract
Background: Mechanical power is a summary variable including all the components which can possibly cause VILI (pressures, volume, flow, respiratory rate). Since the complexity of its mathematical computation is one of the major factors that delay its clinical use, we propose here a simple and easy to remember equation to estimate mechanical power under volumecontrolled ventilation:Mechanical Power = VE x (Peak Pressure + PEEP + F/6)/20where the mechanical power is expressed in Joules/minute, the minute ventilation (VE) in liters/minute, the inspiratory flow (F) in liters/minute, and peak pressure and positive endexpiratory pressure (PEEP) in centimeter of water. All the components of this equation are continuously displayed by any ventilator under volumecontrolled ventilation without the need for clinician intervention.To test the accuracy of this new equation, we compared it with the reference formula of mechanical power that we proposed for volumecontrolled ventilation in the past. The comparisons were made in a cohort of mechanically ventilated pigs (485 observations) and in a cohort of ICU patients (265 observations).Results: Both in pigs and in ICU patients, the correlation between our equation and the reference one was close to the identity. Indeed, the R2 ranged from 0.97 to 0.99 and the BlandAltman showed small biases (ranging from + 0.35 to  0.53 J/min) and proportional errors (ranging from + 0.02 to  0.05).Conclusions: Our new equation of mechanical power for volumecontrolled ventilation represents a simple and accurate alternative to the more complex ones available to date. This equation does not need any clinical intervention on the ventilator (such as an inspiratory hold) and could be easily implemented in the software of any ventilator in volumecontrolled mode. This would allow the clinician to have an estimation of mechanical power at a simple glance and thus increase the clinical consciousness of this variable which is still far from being used at the bedside. Our equation carries the same limitations of all other formulas of mechanical power, the most important of which, as far as it concerns VILI prevention, are the lack of normalization and its application to the whole respiratory system (including the chest wall) and not only to the lung parenchyma.File  Dimensione  Formato  

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