Accuracy of P0.1 displayed by modern ventilators - A bench study
CCCF ePoster library. Telias I. Nov 1, 2016; 150933; 56 Disclosure(s): Dr. Laurent Brochards' laboratory has received equipement or research grants from Maquet, General Electric, Fisher and Paykel , Air Liquide and Philips.
Irene Telias
Irene Telias
Login now to access Regular content available to all registered users.

You may also access this content "anytime, anywhere" with the Free MULTILEARNING App for iOS and Android
Rate & Comment (0)

Topic: Basic or Translational Science

Accuracy of P0.1 displayed by modern ventilators – A bench study

Telias, Irene G1,2,3; Junhasavasdikul, Detajin1,3,4 ;Rittayamai, Nuttapol5; Chen, Lu1,3,; Luca Grieco, Domenico1,3,6; Dres, Martin1,3; Goligher, Ewan C1,2; Brochard Laurent J1,3
1Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, Canada. 2 Division of Respirology, Department of Medicine, University Health Network and Mount Sinai Hospital, Toronto, Canada.3Keenan Research Centre for Biomedical Science, Li Ka Shing Knowledge Institute, St Michael’s Hospital, Toronto, Canada. 4Division of Pulmonary and Critical Care, Department of Medicine, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand.5Division of Respiratory Diseases and Tuberculosis, Department of Medicine, Faculty of Medicine, Siriraj Hospital, Bangkok, Thailand. 6Department of Anesthesia and Intensive Care Medicine, Catholic University of The Sacred Heart, Rome, Italy.


Esophageal manometry (Peso) is used to measure inspiratory effort however is rarely implemented in clinical practice1. Airway occlusion pressure (P0.1) — drop in airway pressure during the first 100 msec of a breath against an occluded airway2— is a non-invasive tool to assess respiratory drive and has been shown to correlate the presssure-time product (PTPes)3. Moreover, we found that P0.1 can be used to detect excessive levels of inspiratory effort. A P0.1 higher than 3.5cmH2O indicates a PTPes higher than 200cmH2.s/min with a sensitivity of 86% and a specificity of 77%. Nonetheless, the procedure to measure P0.1 requires special equipement and offline analysis of the data, making it difficult to preform at the bedside. Modern ventilators have introduced algorithms to automatically measure P0.1, however there is limited data on the accuracy of this method.
To compare P0.1 displayed on the screen of two modern ventilators and P0.1 measured by visual assesment of the airway pressure (Paw) tracing in different mechanical conditions and range of inspiratory efforts using a lung simulator.
A lung simulator (ASL 5000, Ingmar Medical) was connected to two ventilators (SERVO-i, Maquet -Vent1- and GE CARESCAPE R860, General Electric -Vent2). A normal and obstructive lung model were simulated. Eighteen patterns of patients’ effort where simulated for each condition. Paw and flow where measured using a differential pressure transducer connected to the Y-piece.
Vent1 displays P0.1 estimated per breath and Vent2 performs an occlusion to measure P0.1. During each combination of lung and patient effort, while connected to Vent1, five consecutive values of P0.1 displayed on the screen were recorded (P0.1vent1). Then 3 occlusions were performed and P0.1 was measured offline (P0.1man1). With Vent2 three occlusions were performed, P0.1 displayed on the screen was recorded (P0.1vent2) and then measured offline (P0.1man2).
Correlation between P0.1vent and P0.1man was assessed by a linear regression model and the accuracy was evaluated using the Bland and Altman method for each ventilator. Preliminary results are reported.
With Vent1 36 combinations were performed and analyzed, with Vent2 36 combinations were performed and 4 were discard due to ineffective efforts. The range of P0.1man was 0.2 – 10.4cmH2O. The intrinsic positive end-expiratory pressure (PEEPi) ranged from 0 - 9cmH2O.
For Vent1 the correlation between P0.1vent1 and P0.1man1 was 0.91 (p<0.001). The bias was -1.7 +/- 1.5 cmH2O doing the average of 3 P0.1vent1 and -1.1 +/- 1.3 cmH2O doing the average of five P0.1vent1 (FIGURE 1). In combinations without PEEPi (N=21) bias was -0.7 +/- 0.7 cmH2O.
For Vent2, the correlation was 0.97 with a p<0.001 and bias of -0.1+/- 0.7cmH2O (FIGURE 2). In the combinations without PEEPi (N=18) the bias was 0.1 +/- 0.31cmH2O.
Accuracy of P0.1 displayed by the Servo-i ventilator is low particularly at higher values of P0.1 and improves when more values of P0.1 are considered. The accuracy of P0.1 displayed by the GE CARESCAPE R860 ventilator is good in a wide range of inspiratory efforts and mechanical conditions.
In both cases, there is a sign towards the negative impact of PEEPi on the accuracy. The difference in the performance of both ventilators is probably related to the algorithm that they use to display P0.1. Breath-by-breath variability of P0.1 seen in patients was not considered.


1Goligher EC, Ferguson ND, Brochard LJ. Clinical challenges in mechanical ventilation. Lancet Respir Med 2016;4:407-18
2Whitelaw WA, Derenne JP, Milic-Emili J. Occlusion pressure as a measure of respiratory center output in conscious man. Respiration physiology 1975;23(2):181-199
3Mancebo J, Albadalejo P, Touchard D, Bak E, Subirana M, Lamaire F, Harf A, Brochard L. Airway occlusion pressure to titrate positive end-expiratory pressure in patients with dynamic hyperinflation. Anesthesiology 2000;93(1):81-90

Document: File 1 File 2
    This eLearning portal is powered by:
    This eLearning portal is powered by MULTIEPORTAL
Anonymous User Privacy Preferences

Strictly Necessary Cookies (Always Active)

MULTILEARNING platforms and tools hereinafter referred as “MLG SOFTWARE” are provided to you as pure educational platforms/services requiring cookies to operate. In the case of the MLG SOFTWARE, cookies are essential for the Platform to function properly for the provision of education. If these cookies are disabled, a large subset of the functionality provided by the Platform will either be unavailable or cease to work as expected. The MLG SOFTWARE do not capture non-essential activities such as menu items and listings you click on or pages viewed.

Performance Cookies

Performance cookies are used to analyse how visitors use a website in order to provide a better user experience.

Save Settings