scholarly journals Effects of pressure- and volume-controlled ventilation on the work of breathing in cats using a cuffed endotracheal tube

2021 ◽  
pp. 2568-2573
Author(s):  
Nutawan Niyatiwatchanchai ◽  
Naris Thengchaisri
Keyword(s):  
Blood Pressure ◽  
General Anesthesia ◽  
Endotracheal Tube ◽  
Respiratory Function ◽  
Minute Ventilation ◽  
Work Of Breathing ◽  
Cuffed Endotracheal Tube ◽  
Controlled Ventilation ◽  
Volume Controlled Ventilation ◽  
Volume Controlled

Background and Aim: Mechanical ventilation is essential for supporting patients' respiratory function when they are under general anesthesia. For cats with limited lung capacity, the different effects of volume-controlled ventilation (VCV) and pressure-controlled ventilation (PCV) on respiratory function remain elusive. The objective of the present study was to compare the efficacy of VCV and PCV in cats under general anesthesia using a cuffed endotracheal tube (ETT). Materials and Methods: Twelve healthy cats were randomly allocated to either a VCV or PCV group. Five tidal volumes (6, 8, 10, 12, and 14 mL/kg) were randomly applied to assess the efficacy of VCV, and respiratory rates were adjusted to achieve a minute ventilation of 100 mL/kg/min. Peak inspiratory pressures (4, 5, 6, 7, and 8 mmHg) were randomly applied to assess the efficacy of PCV, and respiratory rates were adjusted to achieve a minute ventilation of 100 mL/kg/min. Blood pressure, gas leakages, and end-tidal CO2 were recorded from 60 trials for airway control during the use of VCV or PCV. Data were compared using Fisher's exact test with a significance level of p<0.05. Results: Leakages did not differ between VCV (1/60 events) and PCV (0/60 events; p=0.500). Hypercapnia was identified when using VCV (6/60 events) less frequently than when using PCV (7/60 events; p=0.762), but did not reach statistical significance. Hypotension (mean arterial blood pressure <60 mmHg) occurred less frequently with VCV (0/60 events) than with PCV (9/60 events; p=0.003). Moreover, VCV provided a significantly lower work of breathing (151.10±65.40 cmH2O mL) compared with PCV (187.84±89.72 cmH2O mL; p<0.05). Conclusion: VCV in cats using a cuffed ETT causes less hypotension than PCV. It should be noted that VCV provides a more stable tidal volume compared with PCV, resulting in a more stable minute volume. Nonetheless, VCV should not be used in patients with an airway obstruction because higher peak airway pressure may occur and lead to lung injury.

scholarly journals Mechanical power at a glance: a simple surrogate for volume-controlled ventilation

2019 ◽  
Vol 7 (1) ◽  
Author(s):  
Lorenzo Giosa ◽  
Mattia Busana ◽  
Iacopo Pasticci ◽  
Matteo Bonifazi ◽  
Matteo Maria Macrì ◽  
...  
Keyword(s):  
Peak Pressure ◽  
Minute Ventilation ◽  
Clinical Intervention ◽  
Lung Parenchyma ◽  
Mechanical Power ◽  
Icu Patients ◽  
Controlled Ventilation ◽  
Volume Controlled Ventilation ◽  
New Equation ◽  
Volume Controlled

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 volume-controlled ventilation: $$ \mathrm{Mechanical}\ \mathrm{Power}=\frac{\mathrm{VE}\times \left(\mathrm{Peak}\ \mathrm{Pressure}+\mathrm{PEEP}+F/6\right)}{20} $$Mechanical Power=VE×Peak Pressure+PEEP+F/620 where 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 end-expiratory pressure (PEEP) in centimeter of water. All the components of this equation are continuously displayed by any ventilator under volume-controlled 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 volume-controlled 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 Bland-Altman 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 volume-controlled 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 volume-controlled 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.

scholarly journals The effects of pressure- versus volume-controlled ventilation on ventilator work of breathing

2020 ◽  
Vol 19 (1) ◽  
Author(s):  
Mojdeh Monjezi ◽  
Hamidreza Jamaati
Keyword(s):  
Work Of Breathing ◽  
Normal Subjects ◽  
Inspiratory Flow ◽  
Flow Profile ◽  
Controlled Ventilation ◽  
Volume Controlled Ventilation ◽  
Copd Patients ◽  
Flow Waveforms ◽  
Lung Airways ◽  
Volume Controlled

Abstract Background Measurement of work of breathing (WOB) during mechanical ventilation is essential to assess the status and progress of intensive care patients. Increasing ventilator WOB is known as a risk factor for ventilator-induced lung injury (VILI). In addition, the minimization of WOB is crucial to facilitate the weaning process. Several studies have assessed the effects of varying inspiratory flow waveforms on the patient’s WOB during assisted ventilation, but there are few studies on the different effect of inspiratory flow waveforms on ventilator WOB during controlled ventilation. Methods In this paper, we analyze the ventilator WOB, termed mechanical work (MW) for three common inspiratory flow waveforms both in normal subjects and COPD patients. We use Rohrer’s equation for the resistance of the endotracheal tube (ETT) and lung airways. The resistance of pulmonary and chest wall tissue are also considered. Then, the resistive MW required to overcome each component of the respiratory resistance is computed for square and sinusoidal waveforms in volume-controlled ventilation (VCV), and decelerating waveform of flow in pressure-controlled ventilation (PCV). Results The results indicate that under the constant I:E ratio, a square flow profile best minimizes the MW both in normal subjects and COPD patients. Furthermore, the large I:E ratio may be used to lower MW. The comparison of results shows that ETT and lung airways have the main contribution to resistive MW in normals and COPDs, respectively. Conclusion These findings support that for lowering the MW especially in patients with obstructive lung diseases, flow with square waveforms in VCV, are more favorable than decelerating waveform of flow in PCV. Our analysis suggests the square profile is the best choice from the viewpoint of less MW.

scholarly journals Comparison of Volume-Guaranteed or -Targeted, Pressure-Controlled Ventilation with Volume-Controlled Ventilation during Elective Surgery: A Systematic Review and Meta-Analysis

2021 ◽  
Vol 10 (6) ◽  
pp. 1276
Author(s):  
Volker Schick ◽  
Fabian Dusse ◽  
Ronny Eckardt ◽  
Steffen Kerkhoff ◽  
Simone Commotio ◽  
...  
Keyword(s):  
Systematic Review ◽  
Elective Surgery ◽  
Meta Analysis ◽  
Lung Ventilation ◽  
One Lung Ventilation ◽  
Controlled Ventilation ◽  
Pressure Controlled Ventilation ◽  
Volume Controlled Ventilation ◽  
Volume Controlled ◽  
Pressure Controlled

For perioperative mechanical ventilation under general anesthesia, modern respirators aim at combining the benefits of pressure-controlled ventilation (PCV) and volume-controlled ventilation (VCV) in modes typically named “volume-guaranteed” or “volume-targeted” pressure-controlled ventilation (PCV-VG). This systematic review and meta-analysis tested the hypothesis that PCV-VG modes of ventilation could be beneficial in terms of improved airway pressures (Ppeak, Pplateau, Pmean), dynamic compliance (Cdyn), or arterial blood gases (PaO2, PaCO2) in adults undergoing elective surgery under general anesthesia. Three major medical electronic databases were searched with predefined search strategies and publications were systematically evaluated according to the Cochrane Review Methods. Continuous variables were tested for mean differences using the inverse variance method and 95% confidence intervals (CI) were calculated. Based on the assumption that intervention effects across studies were not identical, a random effects model was chosen. Assessment for heterogeneity was performed with the χ2 test and the I2 statistic. As primary endpoints, Ppeak, Pplateau, Pmean, Cdyn, PaO2, and PaCO2 were evaluated. Of the 725 publications identified, 17 finally met eligibility criteria, with a total of 929 patients recruited. Under supine two-lung ventilation, PCV-VG resulted in significantly reduced Ppeak (15 studies) and Pplateau (9 studies) as well as higher Cdyn (9 studies), compared with VCV [random effects models; Ppeak: CI −3.26 to −1.47; p < 0.001; I2 = 82%; Pplateau: −3.12 to −0.12; p = 0.03; I2 = 90%; Cdyn: CI 3.42 to 8.65; p < 0.001; I2 = 90%]. For one-lung ventilation (8 studies), PCV-VG allowed for significantly lower Ppeak and higher PaO2 compared with VCV. In Trendelenburg position (5 studies), this effect was significant for Ppeak only. This systematic review and meta-analysis demonstrates that volume-targeting, pressure-controlled ventilation modes may provide benefits with respect to the improved airway dynamics in two- and one-lung ventilation, and improved oxygenation in one-lung ventilation in adults undergoing elective surgery.

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