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.

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.

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 A Novel Multi-ventilation Technique to Split Ventilators

2020 ◽  
Author(s):  
Albert Lee ◽  
Soban Umar ◽  
Nir N. Hoftman
Keyword(s):  
Severe Acute Respiratory Syndrome ◽  
Tidal Volume ◽  
Pressure Control ◽  
Healthcare Systems ◽  
Viable Alternative ◽  
Control Mode ◽  
Positive End Expiratory Pressure ◽  
Compliance Requirements ◽  
Ventilation Technique ◽  
Human Participants

ABSTRACTBackgroundDespite efforts to initially contain Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV-2), it has spread worldwide and has strained international healthcare systems to the point where advanced respiratory resources and ventilators are depleted. This study aims to explore splitting ventilators, or “multi-ventilation,” as a viable alternative in these demanding times. We investigated whether individualized tidal volume and positive end expiratory pressure (PEEP) delivery is possible to lungs of different compliances that are being simultaneously ventilated from one anesthesia ventilator.MethodsWe performed a controlled experiment in an operating room environment without animal or human participants. Two “test lungs” were connected to distinct modified Y-pieces that were ventilated in parallel from a single anesthesia ventilator.ResultsVentilation can be manipulated to qualitatively deliver individually tailored tidal volumes in the setting of varying PEEP and compliance requirements in pressure control mode.ConclusionsSplitting ventilators, or “multi-ventilation,” is a viable alternative to acute ventilator shortage during a pandemic. Ventilators can be split for individualized tidal volume and positive end-expiratory pressure delivery in multiple subjects of differing compliances and demographics.

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.

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.

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