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Performance of ICU ventilators during noninvasive ventilation with large leaks in a total face mask: a bench study.

Nakamura MA, Costa EL, Carvalho CR, Tucci MR - J Bras Pneumol (2014 May-Jun)

Bottom Line: The variables analyzed were ventilation trigger, cycling off, total leak, and pressurization.Of the eight ICU ventilators tested, four did not work (autotriggering or inappropriate turning off due to misdetection of disconnection); three worked with some problems (low PEEP or high cycling delay); and one worked properly.The majority of the ICU ventilators tested were not suitable for NIV with a leaky TFM.

View Article: PubMed Central - PubMed

Affiliation: Heart Institute, Hospital das Clínicas, School of Medicine, University of São Paulo, São Paulo, Brazil.

ABSTRACT

Objective: Discomfort and noncompliance with noninvasive ventilation (NIV) interfaces are obstacles to NIV success. Total face masks (TFMs) are considered to be a very comfortable NIV interface. However, due to their large internal volume and consequent increased CO2 rebreathing, their orifices allow proximal leaks to enhance CO2 elimination. The ventilators used in the ICU might not adequately compensate for such leakage. In this study, we attempted to determine whether ICU ventilators in NIV mode are suitable for use with a leaky TFM.

Methods: This was a bench study carried out in a university research laboratory. Eight ICU ventilators equipped with NIV mode and one NIV ventilator were connected to a TFM with major leaks. All were tested at two positive end-expiratory pressure (PEEP) levels and three pressure support levels. The variables analyzed were ventilation trigger, cycling off, total leak, and pressurization.

Results: Of the eight ICU ventilators tested, four did not work (autotriggering or inappropriate turning off due to misdetection of disconnection); three worked with some problems (low PEEP or high cycling delay); and one worked properly.

Conclusions: The majority of the ICU ventilators tested were not suitable for NIV with a leaky TFM.

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Related in: MedlinePlus

Representation of the variables measured. Pressure (upper) and flow(lower) tracings of a hypothetical measurement with positive end-expiratorypressure (PEEP) of 5 cmH2O and pressure support (PS) of10cmH2O. In the middle, tracing of the pressure for the driveventilator. The upper tracing shows the inspiratory pressure-time product at500 ms (PTP500; light gray area) and at 1 s (PTPt; dark gray area plus lightgray area), both expressed in percentage of ideal area (line-shadedareas)
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f01: Representation of the variables measured. Pressure (upper) and flow(lower) tracings of a hypothetical measurement with positive end-expiratorypressure (PEEP) of 5 cmH2O and pressure support (PS) of10cmH2O. In the middle, tracing of the pressure for the driveventilator. The upper tracing shows the inspiratory pressure-time product at500 ms (PTP500; light gray area) and at 1 s (PTPt; dark gray area plus lightgray area), both expressed in percentage of ideal area (line-shadedareas)

Mentions: We measured the following variables (Figure 1):proximal inspiratory pressure (PIP) at the end of the inspiratory phase, incmH2O, measured at the proximal sensor; PEEP, in cmH2O;inspiratory leakage, in L/s, determined by the difference between proximal flow anddistal flow at PIF; expiratory leakage, in L/s, by measuring proximal flow at the endof the expiratory phase; PIF, in L/s; tidal volume, in L, calculated by theintegration of the flow signal from the distal flow transducer; trigger delay, in ms,determined by the time elapsed between the onset of inspiratory effort (in pleuralpressure) and the onset of inspiratory flow; cycling-off delay, in ms, measured bythe time from the end of the driving inspiratory effort to the end of the ventilatorinspiratory flow; and inspiratory pressure-time product at 500 ms and at 1 s (PTP500and PTPt, respectively), determined by computing the area under the pressure-timecurve between the onset of inspiratory effort and these two times.


Performance of ICU ventilators during noninvasive ventilation with large leaks in a total face mask: a bench study.

Nakamura MA, Costa EL, Carvalho CR, Tucci MR - J Bras Pneumol (2014 May-Jun)

Representation of the variables measured. Pressure (upper) and flow(lower) tracings of a hypothetical measurement with positive end-expiratorypressure (PEEP) of 5 cmH2O and pressure support (PS) of10cmH2O. In the middle, tracing of the pressure for the driveventilator. The upper tracing shows the inspiratory pressure-time product at500 ms (PTP500; light gray area) and at 1 s (PTPt; dark gray area plus lightgray area), both expressed in percentage of ideal area (line-shadedareas)
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4109202&req=5

f01: Representation of the variables measured. Pressure (upper) and flow(lower) tracings of a hypothetical measurement with positive end-expiratorypressure (PEEP) of 5 cmH2O and pressure support (PS) of10cmH2O. In the middle, tracing of the pressure for the driveventilator. The upper tracing shows the inspiratory pressure-time product at500 ms (PTP500; light gray area) and at 1 s (PTPt; dark gray area plus lightgray area), both expressed in percentage of ideal area (line-shadedareas)
Mentions: We measured the following variables (Figure 1):proximal inspiratory pressure (PIP) at the end of the inspiratory phase, incmH2O, measured at the proximal sensor; PEEP, in cmH2O;inspiratory leakage, in L/s, determined by the difference between proximal flow anddistal flow at PIF; expiratory leakage, in L/s, by measuring proximal flow at the endof the expiratory phase; PIF, in L/s; tidal volume, in L, calculated by theintegration of the flow signal from the distal flow transducer; trigger delay, in ms,determined by the time elapsed between the onset of inspiratory effort (in pleuralpressure) and the onset of inspiratory flow; cycling-off delay, in ms, measured bythe time from the end of the driving inspiratory effort to the end of the ventilatorinspiratory flow; and inspiratory pressure-time product at 500 ms and at 1 s (PTP500and PTPt, respectively), determined by computing the area under the pressure-timecurve between the onset of inspiratory effort and these two times.

Bottom Line: The variables analyzed were ventilation trigger, cycling off, total leak, and pressurization.Of the eight ICU ventilators tested, four did not work (autotriggering or inappropriate turning off due to misdetection of disconnection); three worked with some problems (low PEEP or high cycling delay); and one worked properly.The majority of the ICU ventilators tested were not suitable for NIV with a leaky TFM.

View Article: PubMed Central - PubMed

Affiliation: Heart Institute, Hospital das Clínicas, School of Medicine, University of São Paulo, São Paulo, Brazil.

ABSTRACT

Objective: Discomfort and noncompliance with noninvasive ventilation (NIV) interfaces are obstacles to NIV success. Total face masks (TFMs) are considered to be a very comfortable NIV interface. However, due to their large internal volume and consequent increased CO2 rebreathing, their orifices allow proximal leaks to enhance CO2 elimination. The ventilators used in the ICU might not adequately compensate for such leakage. In this study, we attempted to determine whether ICU ventilators in NIV mode are suitable for use with a leaky TFM.

Methods: This was a bench study carried out in a university research laboratory. Eight ICU ventilators equipped with NIV mode and one NIV ventilator were connected to a TFM with major leaks. All were tested at two positive end-expiratory pressure (PEEP) levels and three pressure support levels. The variables analyzed were ventilation trigger, cycling off, total leak, and pressurization.

Results: Of the eight ICU ventilators tested, four did not work (autotriggering or inappropriate turning off due to misdetection of disconnection); three worked with some problems (low PEEP or high cycling delay); and one worked properly.

Conclusions: The majority of the ICU ventilators tested were not suitable for NIV with a leaky TFM.

Show MeSH
Related in: MedlinePlus