Dataset Information

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

ABSTRACT:

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 (P0.1_vent) 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 (P0.1_ref). The pressure drop after 100 ms was measured offline on the airway pressure-time curves recorded during the automated P0.1 measurements (P0.1_aw). P0.1_vent was compared to P0.1_ref and to P0.1_aw. To assess the potential impact of the circuit length, P0.1 were also measured with circuits of different lengths (P0.1_circuit).

Results

Variations of P0.1_vent correlated well with variations of P0.1_ref. Overall, P0.1_vent underestimated P0.1_ref except for the Löwenstein^® ventilator at P0.1_ref 2.5 cm H₂O and for the Getinge group^® ventilator at P0.1_ref 10 cm H₂O. The agreement between P0.1_vent and P0.1_ref 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 P0.1_vent and P0.1_aw 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 P0.1_circuit values.

Conclusion

P0.1_vent relative changes are well correlated to P0.1_ref changes in all the tested ventilators. Accuracy of absolute values of P0.1_vent varies according to the ventilator model. Overall, P0.1_vent underestimates P0.1_ref. The length of the circuit may partially explain P0.1_vent underestimation.

SUBMITTER: Beloncle F

PROVIDER: S-EPMC6744533 | biostudies-literature | 2019 Sep

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

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

Beloncle François F Piquilloud Lise L Olivier Pierre-Yves PY Vuillermoz Alice A Yvin Elise E Mercat Alain A Richard Jean-Christophe JC

Annals of intensive care 20190913 1

<h4>Background</h4>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 automat ...[more]

PMID: 31520230

Similar Datasets

Project description:BACKGROUND:Undernutrition is an important risk factor for childhood mortality, and remains a major problem facing many developing countries. Millennium Development Goal 1 calls for a reduction in underweight children, implemented through a variety of interventions. To adequately judge the impact of these interventions, it is important to know the reproducibility of the main indicators for undernutrition. In this study, we trained individuals from rural communities in Ethiopia in anthropometry techniques and measured intra- and inter-observer reliability. METHODS AND FINDINGS:We trained 6 individuals without prior anthropometry experience to perform weight, height, and middle upper arm circumference (MUAC) measurements. Two anthropometry teams were dispatched to 18 communities in rural Ethiopia and measurements performed on all consenting pre-school children. Anthropometry teams performed a second independent measurement on a convenience sample of children in order to assess intra-anthropometrist reliability. Both teams measured the same children in 2 villages to assess inter-anthropometrist reliability. We calculated several metrics of measurement reproducibility, including the technical error of measurement (TEM) and relative TEM. In total, anthropometry teams performed measurements on 606 pre-school children, 84 of which had repeat measurements performed by the same team, and 89 of which had measurements performed by both teams. Intra-anthropometrist TEM (and relative TEM) were 0.35 cm (0.35%) for height, 0.05 kg (0.39%) for weight, and 0.18 cm (1.27%) for MUAC. Corresponding values for inter-anthropometrist reliability were 0.67 cm (0.75%) for height, 0.09 kg (0.79%) for weight, and 0.22 kg (1.53%) for MUAC. Inter-anthropometrist measurement error was greater for smaller children than for larger children. CONCLUSION:Measurements of height and weight were more reproducible than measurements of MUAC and measurements of larger children were more reliable than those for smaller children. Community-drawn anthropometrists can provide reliable measurements that could be used to assess the impact of interventions for childhood undernutrition.

Project description:BackgroundThe assessment of spinal stiffness by manual palpation in clinical settings has demonstrated both poor accuracy and reliability. More recently, mechanical methods for assessment of spinal stiffness have demonstrated superior accuracy and reliability. However, mechanical methods of spinal stiffness assessment can be expensive, time consuming and/or unsuited to clinical practice. While a new device has been designed to address these issues (VerteTrack), its benchtop performance remains unknown.AimTo measure the bench-top performance of VerteTrack.MethodsA series of laboratory-based experiments were conducted in February 2018 to investigate the accuracy (precision and bias) of load and displacement measurements obtained by VerteTrack and then were compared against an appropriate reference standard. Measurements of both multiple-level continuous assessment (multiple spinal levels measured), and single-level assessment (single spinal level measured) were performed on a viscoelastic foam medium (AIREX® balance beam, Switzerland) and the resulting stiffness calculated.ResultsVerteTrack demonstrated high precision at all loads and displacements. There was minimal systematic measurement bias identified for applied versus reference load (mean bias = - 0.123 N; 95%CI - 0.182 to 0.428 N, p < .001), and no systematic measurement bias for measured versus reference displacement (mean difference = 0.02 mm; 95%CI - 0.09 to 0.14 mm, p < .001). The magnitude of stiffness obtained during multiple-level continuous assessment was on average 0.25 N/mm (2.79%) less than that for single-level assessment (95%CI - 0.67 to 0.17 N/mm, p < .001).ConclusionsVerteTrack demonstrated high accuracy (high precision, low bias) under bench-top conditions. The difference in stiffness found between multiple versus single spinal levels should be considered in the research context, but is unlikely to be clinically relevant. The results of this study demonstrate that VerteTrack may be suitable for both single and multi-level spinal stiffness measurements in-vivo.

Project description:BackgroundAn algorithm for distinguishing invasive pulmonary aspergillosis (IPA) in critically ill patients (AspICU) has been proposed but not tested.MethodsThis was a prospective observational study applying the AspICU protocol to patients with positive Aspergillus culture (PAC group) and those with negative aspergillus culture but positive galactomannan test in respiratory tract samples (only positive galactomannan (OPG group)). Patients underwent a standardized diagnostic workup with bronchoscopy, computed tomography (CT), and galactomannan determination in serum and bronchoalveolar lavage fluid (BALF).ResultsWe included 85 patients in the study. Of these, 43 had positive aspergillus cultures and 42 patients had only a positive galactomannan test. There were no statistically significant differences in baseline characteristics, underlying conditions or ICU scores between the two groups. The galactomannan titre in BALF was significantly higher in the positive aspergillus culture (PAC) group (enzyme immunoassay (EIA) 5.9, IQR 3.2-5.7) than in the OPG group (EIA 1.7, IQR 0.9-4.5) (p < 0.001). Classic features of IPA were detected on CT in 37.5 % and 36.6 % of patients in the PAC and OPG groups, respectively. There were no statistically significant differences between the PAC and the OPG group in relation to AspICU or European Organization for the Research and Treatment of Cancer (EORTC) criteria. A positive aspergillus culture was a stronger trigger for initiating antimycotic treatment than positive BALF galactomannan: 88.4 % of patients in the PAC group were regarded by clinicians as having IPA and received antimycotic treatment as opposed to 59.5 % in the OPG group (p = 0.002). The 180-day mortality was 58.1 % in the PAC group and 59.5 % in the OPG group.ConclusionsThe inclusion of BALF galactomannan as an additional entry criterion for the AspICU clinical algorithm could increase the diagnostic sensitivity for IPA in ICU patients.Trial registrationThe study was registered at ClinicalTrials.gov (registration number NCT01866020 ) on 27 May 2013.

Dataset Information

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

Background

Methods

Results

Conclusion

Publications

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

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets