scholarly journals Simultaneous ventilation in the Covid-19 pandemic. A bench study

PLoS ONE ◽  
2021 ◽  
Vol 16 (1) ◽  
pp. e0245578
Author(s):  
Claude Guérin ◽  
Martin Cour ◽  
Neven Stevic ◽  
Florian Degivry ◽  
Erwan L’Her ◽  
...  
Keyword(s):  
Clinical Setting ◽  
Research Laboratory ◽  
Pressure Control ◽  
University Hospital ◽  
Control Mode ◽  
Volume Control ◽  
Expiratory Resistance ◽  
Air Volume ◽  
B Test ◽  
Flow Splitter

COVID-19 pandemic sets the healthcare system to a shortage of ventilators. We aimed at assessing tidal volume (VT) delivery and air recirculation during expiration when one ventilator is divided into 2 test-lungs. The study was performed in a research laboratory in a medical ICU of a University hospital. An ICU (V500) and a lower-level ventilator (Elisée 350) were attached to two test-lungs (QuickLung) through a dedicated flow-splitter. A 50 mL/cmH2O Compliance (C) and 5 cmH2O/L/s Resistance (R) were set in both A and B test-lungs (A C50R5 / B C50R5, step1), A C50-R20 / B C20-R20 (step 2), A C20-R20 / B C10-R20 (step 3), and A C50-R20 / B C20-R5 (step 4). Each ventilator was set in volume and pressure control mode to deliver 800mL VT. We assessed VT from a pneumotachograph placed immediately before each lung, pendelluft air, and expiratory resistance (circuit and valve). Values are median (1st-3rd quartiles) and compared between ventilators by non-parametric tests. Between Elisée 350 and V500 in volume control VT in A/B test- lungs were 381/387 vs. 412/433 mL in step 1, 501/270 vs. 492/370 mL in step 2, 509/237 vs. 496/332 mL in step 3, and 496/281 vs. 480/329 mL in step 4. In pressure control the corresponding values were 373/336 vs. 430/414 mL, 416/185 vs. 322/234 mL, 193/108 vs. 176/ 92 mL and 422/201 vs. 481/329mL, respectively (P<0.001 between ventilators at each step for each volume). Pendelluft air volume ranged between 0.7 to 37.8 ml and negatively correlated with expiratory resistance in steps 2 and 3. The lower-level ventilator performed closely to the ICU ventilator. In the clinical setting, these findings suggest that, due to dependence of VT to C, pressure control should be preferred to maintain adequate VT at least in one patient when C and/or R changes abruptly and monitoring of VT should be done carefully. Increasing expiratory resistance should reduce pendelluft volume.

scholarly journals Sharing ventilators in the Covid-19 pandemics. A bench study

2020 ◽  
Author(s):  
Claude Guérin ◽  
Martin Cour ◽  
Neven Stevic ◽  
Florian Degivry ◽  
Erwan L’Her ◽  
...  
Keyword(s):  
Tidal Volume ◽  
Healthcare System ◽  
Research Laboratory ◽  
Pressure Control ◽  
University Hospital ◽  
Control Mode ◽  
Volume Control ◽  
Expiratory Resistance ◽  
Air Volume ◽  
Flow Splitter

AbstractCOVID-19 pandemics sets the healthcare system to a shortage of ventilators. We aimed at assessing tidal volume (VT) delivery and air recirculation during expiration when one ventilator is divided into 2 patients. The study was performed in a research laboratory in a medical ICU of a University hospital. An ICU-dedicated (V500) and a lower-level ventilator (Elisée 350) were attached to two test-lungs (QuickLung) through a dedicated flow-splitter. A 50 mL/cmH2O Compliance (C) and 5 cmH2O/L/s Resistance (R) were set in both A and B lungs (step1), C50R20 in A / C20R20 in B (step 2), C20R20 in A / C10R20 in B (step 3), and C50R20 in A / C20R5 in B (step 4). Each ventilator was set in volume and pressure control mode to deliver 0.8L VT. We assessed VT from a pneumotachograph placed immediately before each lung, rebreathed volume, and expiratory resistance (circuit and valve). Values are median (1st-3rd quartiles) and compared between ventilators by non-parametric tests. Between Elisée 350 and V500 in volume control VT in A/B patients were 0.381/0.387 vs. 0.412/0.433L in step 1, 0.501/0.270 vs. 0.492/0.370L in step 2, 0.509/0.237 vs. 0.496/0.332L in step 3, and 0.496/0.281 vs. 0.480/0.329L in step 4. In pressure control the corresponding values were 0.373/0.336 vs. 0.430/0.414L, 0.416/0.185/0.322/0.234L, 0.193/0.108 vs. 0.176/0.092L and 0.422/0.201 vs. 0.481/0.329L, respectively (P<0.001 between ventilators at each step for each volume). Rebreathed air volume ranged between 0.7 to 37.8 ml and negatively correlated with expiratory resistance in steps 2 and 3. The lower-level ventilator performed closely to the ICU-dedicated ventilator. Due to dependence of VT to C pressure control should be used to maintain adequate VT at least in one patient when C and/or R changes abruptly and monitoring of VT should be done carefully. Increasing expiratory resistance should reduce rebreathed volume.

Study of Constant Airflow Rate and Constant Room Pressure Control Systems for Physical Containment Laboratories

1988 ◽  
Vol 31 (1) ◽  
pp. 56-61
Author(s):  
Atsushi Takahashi ◽  
Takao Okada
Keyword(s):  
Control System ◽  
Control Systems ◽  
Static Pressure ◽  
Pressure Control ◽  
Volume Control ◽  
Airflow Rate ◽  
Processing Unit ◽  
Variable Air Volume ◽  
Central Processing ◽  
Air Volume

This study discusses various control systems that can keep the room pressure and supply/exhaust airflow rate at constant levels in "other rooms" of a highly airtight containment facility when the supply/exhaust airflow is shut off in one of the rooms for decontamination purposes. This study has shown that the constant air volume control system (CAV) allows hysteresis to occur at small differentials on the performance curve of the static pressure differentials and that this hysteresis can cause wide fluctuations in room pressure. In contrast, the variable air volume, central processing unit (VAV-CPU) control system can maintain both airflow rates and room pressures. Each room pressure was controllable to the set level, with an error of less than ±0.5 mmH2O even during transient distur bances. This control system limited fluctuations in the airflow to and from each room to 5 percent during the transient responses. This control system also allows power savings in the operation of supply/exhaust fans, because of the reduced airflow rate and the static pressure of the fans, and is considered to be an excellent control system.

Design of Control Scheme for Variable Air Volume Air-Conditioning System

2014 ◽  
Vol 686 ◽  
pp. 113-120
Author(s):  
Fan Zhang
Keyword(s):  
Temperature Control ◽  
Control Unit ◽  
Pressure Control ◽  
Volume Control ◽  
Positive Pressure ◽  
Air Conditioning System ◽  
Variable Air Volume ◽  
Air Volume ◽  
Air Supply ◽  
Control Scheme

The air quantity of variable air volume system for the rooms and the total air quantity of the system changes with the change of room load. Combined with the system composition in the laboratory, the paper determines the control scheme of the variable air volume system, that is, indoor temperature-control, indoor positive pressure control, air distribution static pressure control, air-supply temperature control and new air volume control. The dotted lines with arrows mean the output signals from the control unit to actuator, and the solid lines with arrows represent the input signals from the actuator to the control unit.

scholarly journals Maintenance of end-expiratory recruitment with increased respiratory rate after saline-lavage lung injury

2007 ◽  
Vol 102 (1) ◽  
pp. 331-339 ◽  
Author(s):  
Rebecca S. Syring ◽  
Cynthia M. Otto ◽  
Rebecca E. Spivack ◽  
Klaus Markstaller ◽  
James E. Baumgardner
Keyword(s):  
Cardiac Output ◽  
Lung Injury ◽  
Respiratory Rate ◽  
Pressure Control ◽  
Plateau Pressure ◽  
Control Mode ◽  
Intrinsic Peep ◽  
Mixed Venous Saturation ◽  
Mixed Venous ◽  
Saline Lavage

Cyclical recruitment of atelectasis with each breath is thought to contribute to ventilator-associated lung injury. Extrinsic positive end-expiratory pressure (PEEPe) can maintain alveolar recruitment at end exhalation, but PEEPe depresses cardiac output and increases overdistension. Short exhalation times can also maintain end-expiratory recruitment, but if the mechanism of this recruitment is generation of intrinsic PEEP (PEEPi), there would be little advantage compared with PEEPe. In seven New Zealand White rabbits, we compared recruitment from increased respiratory rate (RR) to recruitment from increased PEEPe after saline lavage. Rabbits were ventilated in pressure control mode with a fraction of inspired O2 (FiO2) of 1.0, inspiratory-to-expiratory ratio of 2:1, and plateau pressure of 28 cmH2O, and either 1) high RR ( 24 ) and low PEEPe (3.5) or 2) low RR ( 7 ) and high PEEPe ( 14 ). We assessed cyclical lung recruitment with a fast arterial Po2 probe, and we assessed average recruitment with blood gas data. We measured PEEPi, cardiac output, and mixed venous saturation at each ventilator setting. Recruitment achieved by increased RR and short exhalation time was nearly equivalent to recruitment achieved by increased PEEPe. The short exhalation time at increased RR, however, did not generate PEEPi. Cardiac output was increased on average 13% in the high RR group compared with the high PEEPe group ( P < 0.001), and mixed venous saturation was consistently greater in the high RR group ( P < 0.001). Prevention of end-expiratory derecruitment without increased end-expiratory pressure suggests that another mechanism, distinct from intrinsic PEEP, plays a role in the dynamic behavior of atelectasis.

Comparison of Biomechanical Forces Generated during Trumpet Performance in Contrasting Settings

2002 ◽  
Vol 17 (4) ◽  
pp. 149-154
Author(s):  
Karendra Devroop ◽  
Kris Chesky
Keyword(s):  
Clinical Setting ◽  
Research Laboratory ◽  
Angular Position ◽  
Performance Data ◽  
Sensor System ◽  
College Level ◽  
Experimental Setting ◽  
Big Band ◽  
Biomechanical Forces ◽  
Trumpet Performance

The primary aim of this study was to investigate how mouthpiece forces may vary as a function of the setting in which the musicians are asked to perform. Ten college-level trumpet players were assessed while playing the same pieces of music in a jazz big band rehearsal and a controlled laboratory/clinical setting. Trumpet force was measured using a custom Trumpet Sensor System that measures mouthpiece forces and angular position. Overall, the results from this study indicate that mouthpiece forces generated in the research laboratory were similar to those in the rehearsal venue. The data indicate no significant differences between the two conditions that warrant concern for collecting performance data in an experimental setting.

Adult respiratory distress syndrome: outcome in a community hospital

1994 ◽  
Vol 3 (5) ◽  
pp. 337-341 ◽  
Author(s):  
D Willms ◽  
M Nield ◽  
I Gocka
Keyword(s):  
Survival Rate ◽  
Respiratory Distress Syndrome ◽  
Respiratory Distress ◽  
Adult Respiratory Distress Syndrome ◽  
Distress Syndrome ◽  
Community Hospital ◽  
Survival Rates ◽  
Pressure Control ◽  
Control Mode ◽  
Significant Difference

BACKGROUND: Published reports indicate that survival rates of patients with adult respiratory distress syndrome have not improved dramatically since the first report of the condition in 1967. However, changes in ventilator strategies and improved critical care management may result in better survival rates in patients with well-defined, severe adult respiratory distress syndrome. OBJECTIVES: To report the outcomes of patients with adult respiratory distress syndrome treated in a community hospital and compare these findings with those in previously published reports. METHODS: A retrospective study design was used. All patients diagnosed with adult respiratory distress syndrome (N = 47) over a 2-year period were studied. RESULTS: For the study patients, the survival rate was 64%; 29% died from respiratory failure alone. Analysis demonstrated that advanced age was not associated with mortality. Pressure-control ventilation was used for 31 patients and there was no significant difference in the presence of barotrauma in the pressure-control mode vs volume ventilation. CONCLUSION: This survival rate exceeds most recently reported rates and thus supports the idea that improvement in treatment of adult respiratory distress syndrome is occurring.

Research on Direct Tension Control of Underfeed Winder

2012 ◽  
Vol 203 ◽  
pp. 18-21
Author(s):  
Hui Fang ◽  
Wei Tang ◽  
Yan Jing Meng
Keyword(s):  
Load Distribution ◽  
Closed Loop ◽  
Pressure Control ◽  
Tension Control ◽  
Volume Control ◽  
Direct Tension ◽  
Dynamic Compensation ◽  
Compensation Control

The paper analyzes the method of direct tension control, provides repaired method of closed loop speed for tension control of underfeed winder, and designs the systematic hardware figuration and software to effectively meet the demands of different volume control. Furthermore, the problems including pressure control of pressing roller, load distribution control of two-drum winder, tension control of paper, and dynamic compensation control were analyzed and solved through the design of hardware and software of S7-300 PLC.

Efficacy of Yttrium-90 Zevalin Outside of Clinical Trials: Preliminary Results of a Retrospective Bi-Center Study

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 5015-5015
Author(s):  
Francesco Cicone ◽  
Francesco Scopinaro ◽  
Sebastien Baechler ◽  
Nicolas Ketterer ◽  
Franz Buchegger ◽  
...  
Keyword(s):  
Clinical Trials ◽  
Clinical Setting ◽  
Patient Population ◽  
Statistical Significance ◽  
University Hospital ◽  
Low Grade ◽  
Number Of Patients ◽  
Significant Difference ◽  
Routine Clinical Setting

Abstract Background and Aim: Due to limited data regarding the efficacy of Radioimmunotherapy with 90Y-Zevalin (RIT-Z) outside of controlled clinical trials, we carried out a biinstitutional, international retrospective study to assess the efficacy of RIT-Z in a routine clinical setting. The relationship between the number of previous therapies and outcomes as well as the response to the last therapy was assessed. Possible differences in outcomes for patients treated in the two different centers were also analyzed. Materials and Methods: Forty-three consecutive patients treated at the University Hospital of Lausanne (CHUV, Switzerland) and at S. Andrea University Hospital of Rome (Italy) were evaluated, none of which had been previously included in clinical trials. Only 31 patients entered the final analysis: patients lost at follow up, undergoing autologous transplantation (ASCT), or treated within the last 3 months were excluded. Efficacy of therapy was evaluated in terms of Overall Survival (OS), Progression Free Survival (PFS), and Time to Next Treatment (TTNT). Survival curves were obtained with the Kaplan- Meier method (statistical significance = p&lt;0.05). Results: Characteristics of the patient population are listed in Table 1. Although 50% of the patients had aggressive histologies, patients treated at S. Andrea had slightly more favorable features than those treated at CHUV. Fourteen patients (45%) had received at least 4 previous treatments, and all had received Rituximab. Fourteen patients (45%) had not responded to the last therapy, while 6 (19%), all treated at S.Andrea, were considered disease-free at the time of RIT-Z, which was administered for consolidation. Median follow up time was 20 months (11.5 vs. 25 months for S.Andrea and CHUV, respectively). Median PFS and TTNT were similar. After achieving a partial response, 2 patients were referred to Rituximab maintenance after RIT-Z and remain progression-free. Median OS was still not attained. Although not statistically significant, a trend towards better outcomes for S. Andrea patients was found. In comparing patients with indolent and aggressive lymphoma, only PFS was found to be significantly different (median PFS: 10 vs. 5 months, p&lt;0.05). In patients with &lt;4 and ≥ 4 previous therapies, twenty month OS was 88% vs. 53.6% (p=0.02), respectively; median TTNT was 22 vs. 5 months (p=0.013), while differences in PFS did not attain statistical significance. The duration of response in non-responders to their last therapy was shorter than in responders: 20-month OS- 44% vs. 94% (p=0.0015), median PFS and TTNT- 3.5 vs. 15 months (p=0.0002) and 4 vs. 15 months (p=0.0001), respectively. Median PFS and TTNT after RIT-Z did not differ from those found after the last therapy. A significant difference in outcomes for heavily pretreated or refractory patients was found in those with low grade follicular lymphoma. Conclusions: Poorer outcomes were found in our patient population treated in a routine clinical setting compared to those enrolled in clinical trials. This may be related to greater heterogeneity of our study cohort which included more patients with unfavorable conditions (e.g. aggressive NHL, ≥4 treatment courses including rituximab in all, and ASCT in 25%). Our results suggest that the best benefit may be expected with RIT-Z either for consolidation or relatively earlier in the course of NHL treatment. Table 1. Total CHUV S. Andrea Population Analyzed (72%) Number of patients 43 23 20 31 Median Age 61 63 58,5 62 Aggressive Histology (FL grade 3 or DLBCL) 18 (41,8%) 8 (34,7%) 10 (50%) 11 (35,5%) Indolent Histology (FL grade 1 or 2) (%) 25 (58,2%) 15 (65,3%) 10 (50%) 20 (64,5%) Patients with ≥4 previous treatments 19 (44,2%) 12 (52,1%) 7 (35%) 14 (45,2%) Patients with previous ASCT 11 (25,6%) 6 (26%) 5 (25%) 8 (25%)

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