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

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
François Beloncle ◽  
Lise Piquilloud ◽  
Pierre-Yves Olivier ◽  
Alice Vuillermoz ◽  
Elise Yvin ◽  
...  
Keyword(s):  
Airway Pressure ◽  
Inspiratory Effort ◽  
Lung Model ◽  
Respiratory Drive ◽  
Test Lung ◽  
Limits Of Agreement ◽  
Bench Study ◽  
Pressure Time ◽  
Bland Altman Method ◽  
Potential Impact

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 (P0.1vent) 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.

HIGH FREQUENCY PERCUSSIVE VENTILATION CAN MIMIC AIRWAY PRESSURE RELEASE VENTILATION IN A TEST LUNG MODEL

2004 ◽  
Vol 32 (Supplement) ◽  
pp. A38
Author(s):  
Faera L Byerly ◽  
Bruce A Cairns ◽  
Kathy A Short ◽  
John A Haithcock ◽  
Lynn Shapiro ◽  
...  
Keyword(s):  
High Frequency ◽  
Airway Pressure ◽  
Airway Pressure Release Ventilation ◽  
Lung Model ◽  
Test Lung ◽  
Pressure Release ◽  
Pressure Release Ventilation

scholarly journals The Effects of Three Manual Hyperinflation Techniques on Pattern of Ventilation in a Test Lung Model

2002 ◽  
Vol 30 (3) ◽  
pp. 283-288 ◽  
Author(s):  
L. Maxwell ◽  
E. R. Ellis
Keyword(s):  
Airway Pressure ◽  
Lung Model ◽  
Peak Airway Pressure ◽  
Treatment Technique ◽  
Valve Closure ◽  
Test Lung ◽  
Flow Rates ◽  
Pair Comparisons ◽  
Expiratory Flow Rates ◽  
Circuit Configuration

Manual hyperinflation (MHI) is used by physiotherapists as a treatment technique in intubated patients. This study investigated the effect of three different MHI techniques using a Mapleson-C circuit configuration with a CIG Medishield valve on volume delivered (Vt), peak inspiratory (PIFR) and expiratory flow rates (PEFR), and peak airway pressure (PAP) in a test lung model. The protocols differed in the degree of valve closure and inclusion of an inspiratory pause. For protocols 1, 2 and 3 the measures were Vt—1.33 (0.21), 2.74 (0.13), 3.55 (0.12) litres; PAP— 14.30 (0.82), 24.00 (0.47), 30.20 (0.92) cmH 2 O and PIFR—1.13 (0.05), 1.51 (0.15), 1.32 (0.09) l/s respectively. All pair comparisons were statistically significant except for PEFR (l/s), which was significantly lower for protocol 1 [1.62 (0.06)], compared to protocols 2 [2.01 (0.25)] and 3 [2.10 (0.19)] but not between protocols 2 and 3. Circuit and technique choice should be considered in relation to the specific therapeutic aim of treatment.

Continuous Positive Airway Pressure in New-generation Mechanical Ventilators

2002 ◽  
Vol 96 (1) ◽  
pp. 162-172 ◽  
Author(s):  
Muneyuki Takeuchi ◽  
Purris Williams ◽  
Dean Hess ◽  
Robert M. Kacmarek
Keyword(s):  
Continuous Positive Airway Pressure ◽  
Delay Time ◽  
Airway Pressure ◽  
Positive Airway Pressure ◽  
Peak Flow ◽  
Pressure Change ◽  
Lung Model ◽  
Mechanical Ventilators ◽  
Pressure Time ◽  
Pressure Time Product

Background A number of new microprocessor-controlled mechanical ventilators have become available over the last few years. However, the ability of these ventilators to provide continuous positive airway pressure without imposing or performing work has never been evaluated. Methods In a spontaneously breathing lung model, the authors evaluated the Bear 1000, Drager Evita 4, Hamilton Galileo, Nellcor-Puritan-Bennett 740 and 840, Siemens Servo 300A, and Bird Products Tbird AVS at 10 cm H(2)O continuous positive airway pressure. Lung model compliance was 50 ml/cm H(2)O with a resistance of 8.2 cm H(2)O x l(-1) x s(-1), and inspiratory time was set at 1.0 s with peak inspiratory flows of 40, 60, and 80 l/min. In ventilators with both pressure and flow triggering, the response of each was evaluated. Results With all ventilators, peak inspiratory flow, lung model tidal volume, and range of pressure change (below baseline to above baseline) increased as peak flow increased. Inspiratory trigger delay time, inspiratory cycle delay time, expiratory pressure time product, and total area of pressure change were not affected by peak flow, whereas pressure change to trigger inspiration, inspiratory pressure time product, and trigger pressure time product were affected by peak flow on some ventilators. There were significant differences among ventilators on all variables evaluated, but there was little difference between pressure and flow triggering in most variables on individual ventilators except for pressure to trigger. Pressure to trigger was 3.74 +/- 1.89 cm H(2)O (mean +/- SD) in flow triggering and 4.48 +/- 1.67 cm H(2)O in pressure triggering (P < 0.01) across all ventilators. Conclusions Most ventilators evaluated only imposed a small effort to trigger, but most also provided low-level pressure support and imposed an expiratory workload. Pressure triggering during continuous positive airway pressure does require a slightly greater pressure than flow triggering.

scholarly journals Efficacy of ventilator waveform observation for detection of patient–ventilator asynchrony during NIV: a multicentre study

2017 ◽  
Vol 3 (4) ◽  
pp. 00075-2017 ◽  
Author(s):  
Federico Longhini ◽  
Davide Colombo ◽  
Lara Pisani ◽  
Francesco Idone ◽  
Pan Chun ◽  
...  
Keyword(s):  
Airway Pressure ◽  
Visual Inspection ◽  
Breathing Pattern ◽  
Flow Time ◽  
Respiratory Drive ◽  
Predictive Values ◽  
Pressure Time ◽  
Diaphragm Electrical Activity ◽  
True Index ◽  
Sensitivity Specificity

The objective of this study was to assess ability to identify asynchronies during noninvasive ventilation (NIV) through ventilator waveforms according to experience and interface, and to ascertain the influence of breathing pattern and respiratory drive on sensitivity and prevalence of asynchronies.35 expert and 35 nonexpert physicians evaluated 40 5-min NIV reports displaying flow–time and airway pressure–time tracings; identified asynchronies were compared with those ascertained by three examiners who evaluated the same reports displaying, additionally, tracings of diaphragm electrical activity. We determined: 1) sensitivity, specificity, and positive and negative predictive values; 2) the correlation between the double true index (DTI) of each report (i.e., the ratio between the sum of true positives and true negatives, and the overall breath count) and the corresponding asynchrony index (AI); and 3) the influence of breathing pattern and respiratory drive on both AI and sensitivity.Sensitivities to detect asynchronies were low either according to experience (0.20 (95% CI 0.14–0.29) for expert versus 0.21 (95% CI 0.12–0.30) for nonexpert, p=0.837) or interface (0.28 (95% CI 0.17–0.37) for mask versus 0.10 (95% CI 0.05–0.16) for helmet, p<0.0001). DTI inversely correlated with the AI (r2=0.67, p<0.0001). Breathing pattern and respiratory drive did not affect prevalence of asynchronies and sensitivity.Patient–ventilator asynchrony during NIV is difficult to recognise solely by visual inspection of ventilator waveforms.

Patient Self-Assessed Passive Range of Motion of the Knee Cannot Replace Health Professional Measurements

2017 ◽  
Vol 30 (08) ◽  
pp. 829-834
Author(s):  
Frank Madsen ◽  
Anders Odgaard ◽  
Jens Borgbjerg
Keyword(s):  
Range Of Motion ◽  
Knee Extension ◽  
Flexion Contracture ◽  
Patient Assessment ◽  
Limits Of Agreement ◽  
Self Assessment ◽  
Knee Motion ◽  
Bland Altman Method ◽  
Flexion And Extension ◽  
Patient Self Assessment

AbstractThe purpose of this study was to investigate whether patients can accurately self-assess their knee passive range of motion (PROM). A picture-based questionnaire for patient self-assessment of knee PROM was developed and posted to patients. The self-assessed PROM from 58 patients was compared with surgeon-assessed PROM using a short-arm goniometer. Agreement between the measurement methods was calculated with the Bland-Altman method. We calculated the sensitivity and specificity of patient-assessed PROM in dichotomously detecting knee motion impairment in both flexion (≤ 100 degrees) and extension (≥ 10-degree flexion contracture). Surgeon- and patient-assessed knee PROM showed a mean difference (95% limits of agreement) of −2.1 degrees (−42.5 to 38.3 degrees) for flexion and −8.1 degrees (−28.8 to 12.7 degrees) for extension. The sensitivity of patient self-assessed PROM in identifying knee flexion and extension impairments was 86 and 100%, respectively, whereas its specificity was 84 and 43%, respectively. Although wide limits of agreement were observed between surgeon- and patient-assessed knee PROM, the picture-based questionnaire for patient assessment of knee ROM was found to be a valid tool for dichotomously detecting knee motion impairment in flexion (≤ 100 degrees). However, the specificity of the questionnaire for detection of knee extension impairments (≥ 10-degree flexion contracture) was low, which limits is practical utility for this purpose.

Patient-ventilator interaction during acute hypercapnia: pressure-support vs. proportional-assist ventilation

1996 ◽  
Vol 81 (1) ◽  
pp. 426-436 ◽  
Author(s):  
V. M. Ranieri ◽  
R. Giuliani ◽  
L. Mascia ◽  
S. Grasso ◽  
V. Petruzzelli ◽  
...  
Keyword(s):  
Respiratory Rate ◽  
Dead Space ◽  
Pressure Support ◽  
Esophageal Pressure ◽  
Respiratory Drive ◽  
Resistive Load ◽  
Proportional Assist Ventilation ◽  
Pressure Time ◽  
Pressure Time Product ◽  
Stimulation Of

The objective of this study was to compare patient-ventilator interaction during pressure-support ventilation (PSV) and proportional-assist ventilation (PAV) in the course of increased ventilatory requirement obtained by adding a dead space in 12 patients on weaning from mechanical ventilation. With PSV, the level of unloading was provided by setting the inspiratory pressure at 20 and 10 cmH2O, whereas with PAV the level of unloading was at 80 and 40% of the elastic and resistive load. Hypercapnia increased (P < 0.001) tidal swing of esophageal pressure and pressure-time product per breath at both levels of PSV and PAV. During PSV, application of dead space increased ventilation (VE) during PSV (67 +/- 4 and 145 +/- 5% during 20 and 10 cmH2O PSV, respectively, P < 0.001). This was due to a relevant increase in respiratory rate (48 +/- 4 and 103 +/- 5% during 20 and 10 cmH2O PSV, respectively, P < 0.001), whereas the increase in tidal volume (VT) played a small role (13 +/- 1 and 21 +/- 2% during 20 and 10 cmH2O PSV, respectively, P < 0.001). With PAV, the increase in VE consequent to hypercapnia (27 +/- 3 and 64 +/- 4% during 80 and 40% PAV, respectively, P < 0.001) was related to the increase in VT (32 +/- 1 and 66 +/- 2% during 80 and 40% PAV, respectively, P < 0.001), respiratory rate remaining unchanged. The increase in pressure-time product per minute and per liter consequent to acute hypercapnia and the sense of breathlessness were significantly (P < 0.001) higher during PSV than during PAV. Our data show that, after hypercapnic stimulation of the respiratory drive, the capability to increase VE through changes in VT modulated by variations in inspiratory muscle effort is preserved only during PAV; the compensatory strategy used to increase VE during PSV requires greater muscle effort and causes more pronounced patient discomfort than during PAV.

scholarly journals Analysis of Agreement between Expired-Air Carbon Monoxide Monitors

2016 ◽  
Vol 12 (2) ◽  
pp. 105-112 ◽  
Author(s):  
Joshua L. Karelitz ◽  
Valerie C. Michael ◽  
Kenneth A. Perkins
Keyword(s):  
Carbon Monoxide ◽  
Paired Data ◽  
Limits Of Agreement ◽  
Bland Altman Method ◽  
Dsm Iv ◽  
Cigarette Dependence ◽  
Mean Differences ◽  
Level Of Agreement ◽  
Expired Air

Introduction: The current study examined the level of agreement in expired-air carbon monoxide (CO) values, focusing especially on those confirming abstinence, between the two most commonly used CO monitors, the Vitalograph BreathCO and the Bedfont piCO+ Smokerlyzer.Methods: Expired-air samples were collected via both monitors from adult dependent smokers (44 M, 34 F) participating in studies using CO values to confirm abstinence durations of: 24 hours, 12 hours, or no abstinence. All met DSM-IV nicotine dependence criteria and had a mean (SD) Fagerström Test of Cigarette Dependence score of 5.1 (1.8). Paired data collected across multiple visits were analyzed by regression-based Bland–Altman method of Limits of Agreement (LoA).Findings: Analysis indicated a lack of agreement in CO measurement between monitors. Overall, the Bedfont monitor gave mean (±SEM) readings 3.83 (±0.23) ppm higher than the Vitalograph monitor. Mean differences between monitors were larger for those ad lib smoking (5.65 ± 0.38 ppm) than those abstaining 12–24 hours (1.71 ± 0.13 ppm). Yet, there also was not consistent agreement in classification of 24-hour abstinence between monitors.Conclusions: Systematic differences in CO readings demonstrate these two very common monitors may not result in interchangeable values, and reported outcomes in smoking research based on CO values may depend on the monitor used.

Simple point of care continuous positive airway pressure delivery device (Jain-CPAP)

2019 ◽  
Vol 5 (1) ◽  
pp. 13-19
Author(s):  
Ashish Jain ◽  
Robert M DiBlasi ◽  
Veena Devgan ◽  
Nisha Kumari ◽  
Kunal Kalra
Keyword(s):  
Continuous Positive Airway Pressure ◽  
Airway Pressure ◽  
Preterm Neonate ◽  
Positive Airway Pressure ◽  
Point Of Care ◽  
Healthcare Providers ◽  
Linear Increase ◽  
Lung Model ◽  
Lung Mechanics ◽  
Mean Pressure

ObjectiveTo describe the effective pressure and FiO2 delivery to a realistic spontaneously breathing lung model using a novel, simple, inexpensive neonatal non-invasive bubble continuous positive airway pressure (CPAP) device.MethodsThis experimental bench study was conducted at Bench Testing Laboratory at a Children’s Hospital. A realistic 3D anatomic airway model of a 28-week preterm neonate was affixed to the ASL5000 Test Lung to simulate spontaneous breathing with lung mechanics that are specific to a preterm neonate. The assembly was constructed on site using easily available nasal prongs, paediatric infusion set with a graduated chamber, three-way stop cocks and oxygen tubing. The adult nasal prong was used as cannulae. However, this assembly had the limitation of the lack of humidification and inability to deliver graduated oxygen. This assembly was attached to the anatomic airway with nasal prongs. Pressure and FiO2 were measured from within the lung model at different flow settings and recorded for 10 breaths.ResultsThere was a linear increase in the mean pressure in the 10 recorded breaths as oxygen flows were increased.ConclusionsOur nasal CPAP is a simple device, as it can be easily assembled at the point of care using simple, affordable supplies by the healthcare providers and can benefit the newborns with respiratory distress in the resource constraint settings.

Supraglottic airway pressure-flow relationships during oronasal airflow partitioning in dogs

1996 ◽  
Vol 81 (5) ◽  
pp. 1958-1964 ◽  
Author(s):  
T. C. Amis ◽  
N. O’Neill ◽  
T. Van Der Touw ◽  
A. Tully ◽  
A. Brancatisano
Keyword(s):  
Electrical Stimulation ◽  
Soft Palate ◽  
Airway Pressure ◽  
Airway Resistance ◽  
Upper Airway ◽  
Oral Route ◽  
Supraglottic Airway ◽  
Respiratory Drive ◽  
Pressure Flow ◽  
Oral Airway

Amis, T. C., N. O’Neill, T. Van der Touw, A. Tully, and A. Brancatisano. Supraglottic airway pressure-flow relationships during oronasal airflow partitioning in dogs. J. Appl. Physiol. 81(5): 1958–1964, 1996.—We studied pressure-flow relationships in the supraglottic airway of eight prone mouth-open anesthetized (intravenous chloralose or pentobarbital sodium) crossbred dogs (weight 15–26 kg) during increasing respiratory drive (CO2administration; n = 4) and during graded-voltage electrical stimulation (SV; n = 4) of the soft palate muscles. During increased respiratory drive, inspiratory airflow occurred via both the nose (V˙n) and mouth (V˙m), with the ratio of V˙n toV˙m [%(V˙n/V˙m)] decreasing maximally from 16.0 ± 7.0 (SD) to 2.4 ± 1.6% ( P < 0.05). Simultaneously, oral airway resistance at peak inspiratory flow decreased from 2.1 ± 1.0 to 0.4 ± 0.4 cmH2O ( P < 0.05), whereas nasal airway resistance did not change (14.4 ± 7.2 to 13.1 ± 5.4 cmH2O; P = 0.29). Inspiratory pressure-flow plots of the oral airway were inversely curvilinear or more complex in nature. Nasal pathway plots, however, demonstrated a positive linear relationship in all animals ( r = 0.87 ± 0.11; all P < 0.001). During electrical stimulation of soft palate muscle contraction accompanied by graded constant-inspiratory airflows of 45–385 ml/s through an isolated upper airway, %(V˙n/V˙m) decreased from 69 ± 50 to 10 ± 13% at a SV of 84 ± 3% of maximal SV ( P < 0.001). At a SV of 85 ± 1% of maximum, normalized oral airway resistance (expressed as percent baseline) fell to 5 ± 3%, whereas normalized nasal resistance was 80 ± 9% (both P< 0.03). Thus control of oronasal airflow partitioning in dogs appears mediated more by alterations in oral route geometry than by closure of the nasopharyngeal airway.

Performance Characteristics of Five New Anesthesia Ventilators and Four Intensive Care Ventilators in Pressure-support Mode

2006 ◽  
Vol 105 (5) ◽  
pp. 944-952 ◽  
Author(s):  
Samir Jaber ◽  
Didier Tassaux ◽  
Mustapha Sebbane ◽  
Yvan Pouzeratte ◽  
Anne Battisti ◽  
...  
Keyword(s):  
Intensive Care Unit ◽  
Intensive Care ◽  
Pressure Support Ventilation ◽  
Gas Flow ◽  
Pressure Support ◽  
Inspiratory Effort ◽  
Performance Characteristics ◽  
Lung Model ◽  
Support Ventilation ◽  
Ventilation Performance

Background During the past few years, many manufacturers have introduced new modes of ventilation in anesthesia ventilators, especially partial-pressure modalities. The current bench test study was designed to compare triggering and pressurization of five new anesthesia ventilators with four intensive care unit ventilators. Methods Ventilators were connected to a two-compartment lung model. One compartment was driven by an intensive care unit ventilator to mimic "patient" inspiratory effort, whereas the other was connected to the tested ventilator. The settings of ventilators were positive end-expiratory pressures of 0 and 5 cm H2O, and pressure-support ventilation levels of 10, 15, and 20 cm H2O with normal and high "patient" inspiratory effort. For the anesthesia ventilators, all the measurements were obtained for a low (1 l/min) and a high (10 l/min) fresh gas flow. Triggering delay, triggering workload, and pressurization at 300 and 500 ms were analyzed. Results For the five tested anesthesia ventilators, the pressure-support ventilation modality functioned correctly. For inspiratory triggering, the three most recent anesthesia machines (Fabius, Drägerwerk AG, Lübeck, Germany; Primus, Drägerwerk AG; and Avance, GE-Datex-Ohemda, Munchen, Germany) had a triggering delay of less than 100 ms, which is considered clinically satisfactory and is comparable to intensive care unit machines. The use of positive end-expiratory pressure modified the quality of delivered pressure support for two anesthesia ventilators (Kion, Siemens AG, Munich, Germany; and Felix, Taema, Antony, France). Three of the five anesthesia ventilators exhibited pressure-support ventilation performance characteristics comparable to those of the intensive care unit machines. Increasing fresh gas flow (1 to 10 l/min) in the internal circuit did not influence the pressure-support ventilation performance of the anesthesia ventilators. Conclusion Regarding trigger sensitivity and the system's ability to meet inspiratory flow during pressure-supported breaths, the most recent anesthesia ventilators have comparable performances of recent-generation intensive care unit ventilators.

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