Work of Breathing and Airway Occlusion Pressure during Assist-Mode Mechanical Ventilation

Sassoon, Catherine S. H.; Mahutte, C. K.; Te, Tue; Simmons, Daniel H.; Light, Richard W.

doi:10.1378/chest.93.3.571

Cited by 44 publications

(8 citation statements)

References 13 publications

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“…A short triggering time (Ͻ 100 ms) may be associated with a lower work of breathing, 15 is below the conscious threshold of inspiratory effort, 16 and may improve patient-ventilator synchrony. [17][18][19] All the turbine ventilators had a trigger time shorter than 100 ms, even with the weak inspiratory effort.…”

Section: Triggeringmentioning

confidence: 99%

Evaluation of Ventilators Used During Transport of Critically Ill Patients: A Bench Study

2013

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OBJECTIVE: To evaluate the most recent transport ventilators' operational performance regarding volume delivery in controlled mode, trigger function, and the quality of pressurization in pressure support mode. METHODS: Eight recent transport ventilators were included in a bench study in order to evaluate their accuracy to deliver a set tidal volume under normal resistance and compliance conditions, ARDS conditions, and obstructive conditions. The performance of the triggering system was assessed by the measure of the decrease in pressure and the time delay required to open the inspiratory valve. The quality of pressurization was obtained by computing the integral of the pressure-time curve for the first 300 ms and 500 ms after the onset of inspiration. RESULTS: For the targeted tidal volumes of 300, 500, and 800 mL the errors ranged from -3% to 48%, -7% to 18%, and -5% to 25% in the normal conditions, -4% to 27%, -2% to 35%, and -3% to 35% in the ARDS conditions, and ؊4% to 53%, ؊6% to 30%, and ؊30% to 28% in the obstructive conditions. In pressure support mode the pressure drop range was 0.4 -1.7 cm H 2 O, the trigger delay range was 68 -198 ms, and the pressurization performance (percent of ideal pressurization, as measured by pressure-time product at 300 ms and 500 ms) ranges were -9% to 44% at 300 ms and 6%-66% at 500 ms (P < .01). CONCLUSIONS: There were important differences in the performance of the tested ventilators. The most recent turbine ventilators outperformed the pneumatic ventilators. The best performers among the turbine ventilators proved comparable to modern ICU ventilators.

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Section: Triggeringmentioning

confidence: 99%

Evaluation of Ventilators Used During Transport of Critically Ill Patients: A Bench Study

2013

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“…In spontaneously breathing non-ventilated healthy subjects, low values around 2 cm H 2 O are observed with normal respiratory drive whereas values greater than 10 cm H 2 O are correlated with very high drive [6]. P0.1 measurement was later used in intubated patient by occluding the ventilator circuit [12, 13]. Automated measurement is now available in modern ICU ventilators either by default or on request using an easy-to-use and safe maneuver [14].…”

Section: Introductionmentioning

confidence: 99%

Accuracy of P0.1 measurements performed by ICU ventilators: a bench study

Beloncle

Piquilloud

Olivier

et al. 2019

Ann. Intensive Care

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Background Occlusion pressure at 100 ms (P0.1), defined as the negative pressure measured 100 ms after the initiation of an inspiratory effort performed against a closed respiratory circuit, has been shown to be well correlated with central respiratory drive and respiratory effort. Automated P0.1 measurement is available on modern ventilators. However, the reliability of this measurement has never been studied. This bench study aimed at assessing the accuracy of P0.1 measurements automatically performed by different ICU ventilators. Methods Five ventilators set in pressure support mode were tested using a two-chamber test lung model simulating spontaneous breathing. P0.1 automatically displayed on the ventilator screen (P0.1vent) was recorded at three levels of simulated inspiratory effort corresponding to P0.1 of 2.5, 5 and 10 cm H2O measured directly at the test lung and considered as the reference values of P0.1 (P0.1ref). The pressure drop after 100 ms was measured offline on the airway pressure–time curves recorded during the automated P0.1 measurements (P0.1aw). P0.1vent was compared to P0.1ref and to P0.1aw. To assess the potential impact of the circuit length, P0.1 were also measured with circuits of different lengths (P0.1circuit). Results Variations of P0.1vent correlated well with variations of P0.1ref. Overall, P0.1vent underestimated P0.1ref except for the Löwenstein® ventilator at P0.1ref 2.5 cm H2O and for the Getinge group® ventilator at P0.1ref 10 cm H2O. The agreement between P0.1vent and P0.1ref assessed with the Bland–Altman method gave a mean bias of − 1.3 cm H2O (limits of agreement: 1 and − 3.7 cm H2O). Analysis of airway pressure–time and flow–time curves showed that all the tested ventilators except the Getinge group® ventilator performed an occlusion of at least 100 ms to measure P0.1. The agreement between P0.1vent and P0.1aw assessed with the Bland–Altman method gave a mean bias of 0.5 cm H2O (limits of agreement: 2.4 and − 1.4 cm H2O). The circuit’s length impacted P0.1 measurements’ values. A longer circuit was associated with lower P0.1circuit values. Conclusion P0.1vent relative changes are well correlated to P0.1ref changes in all the tested ventilators. Accuracy of absolute values of P0.1vent varies according to the ventilator model. Overall, P0.1vent underestimates P0.1ref. The length of the circuit may partially explain P0.1vent underestimation.

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“…1). 21,42,43 When gas delivery is insufficient, the patient is compelled to actively pull against both the impedance of the respiratory system and that of the ventilator. 5 In normal subjects, studied using a visual analog scale to quantify breathlessness, dyspnea and air hunger result when inspiratory flow rate is low.…”

Section: Flowmentioning

confidence: 99%

Optimizing Patient-Ventilator Synchrony

Epstein¹

2001

Seminars in Respiratory and Critical Care Medicine

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Mechanical ventilation assumes the work of breathing, improves gas exchange, and unloads the respiratory muscles, all of which require good synchronization between the patient and the ventilator. Causes for patient-ventilator dyssynchrony include both patient factors (abnormalities of respiratory drive and abnormal respiratory mechanics) and ventilator factors (triggering, flow delivery, breath termination criteria, the level and mode of ventilator support, and imposed work of breathing). Although patient-ventilator dyssynchrony can often be detected on physical exam, careful analysis of ventilator waveforms (pressure-time, flow-time) allows for more precise definition of the underlying cause. Patient-ventilator interaction can be improved by reversing patient factors that alter respiratory drive or elevate patient ventilatory requirements and by correcting factors that contribute to dynamic hyperinflation. Proper setting of the ventilator using sensitive triggering mechanisms, satisfactory flow rates, adequate delivered minute ventilation, matching machine T(I) to neural T(I), and applying modes that overcome the imposed work of breathing, further optimize patient-ventilator synchrony.

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Work of Breathing and Airway Occlusion Pressure during Assist-Mode Mechanical Ventilation

Cited by 44 publications

References 13 publications

Evaluation of Ventilators Used During Transport of Critically Ill Patients: A Bench Study

Evaluation of Ventilators Used During Transport of Critically Ill Patients: A Bench Study

Accuracy of P0.1 measurements performed by ICU ventilators: a bench study

Optimizing Patient-Ventilator Synchrony

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