Regulating inspiratory pressure to individualise tidal volumes in a simulated two-patient, one-ventilator system

Chen, Grant; Hellman, Samuel; Irie, Takeshi; Downey, Robert J.; Fischer, Gregory W.

doi:10.1016/j.bja.2020.06.043

Cited by 10 publications

(9 citation statements)

References 11 publications

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“…As in other reports 7 , 8 , 9 , 10 , a splitter was able to provide a defined and different V T to two patients despite differences in respiratory mechanics. Of note, we tested for the first time in humans whether sudden changes in lung compliance and/or airway resistance in one simulated patient (test lung) affect the other patient (ARDS patient), including extreme conditions such as massive leak and airway occlusion.…”

supporting

confidence: 79%

Assessment of a splitter for protective dual-patient ventilation in patients with acute respiratory distress syndrome

Arellano¹,

Tobar²,

Lazo³

et al. 2022

British Journal of Anaesthesia

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supporting

confidence: 79%

Assessment of a splitter for protective dual-patient ventilation in patients with acute respiratory distress syndrome

Arellano¹,

Tobar²,

Lazo³

et al. 2022

British Journal of Anaesthesia

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“…Recently, many investigators have tried to optimize sharing ventilation by modifying the ventilatory circuits with less or more complicated approaches to ensure greater individualized ventilation and increase the safety profile [ 14 , 16 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 ]. These strategies have been analyzed in silico, in vitro or in vivo to assess the potential safety and feasibility of ventilatory sharing [ 15 , 37 , 38 ].…”

Section: Discussionmentioning

confidence: 99%

Sharing Mechanical Ventilator: In Vitro Evaluation of Circuit Cross-Flows and Patient Interactions

et al. 2021

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During the COVID-19 pandemic, a shortage of mechanical ventilators was reported and ventilator sharing between patients was proposed as an ultimate solution. Two lung simulators were ventilated by one anesthesia machine connected through two respiratory circuits and T-pieces. Five different combinations of compliances (30–50 mL × cmH2O−1) and resistances (5–20 cmH2O × L−1 × s−1) were tested. The ventilation setting was: pressure-controlled ventilation, positive end-expiratory pressure 15 cmH2O, inspiratory pressure 10 cmH2O, respiratory rate 20 bpm. Pressures and flows from all the circuit sections have been recorded and analyzed. Simulated patients with equal compliance and resistance received similar ventilation. Compliance reduction from 50 to 30 mL × cmH2O−1 decreased the tidal volume (VT) by 32% (418 ± 49 vs. 285 ± 17 mL). The resistance increase from 5 to 20 cmH2O × L−1 × s−1 decreased VT by 22% (425 ± 69 vs. 331 ± 51 mL). The maximal alveolar pressure was lower at higher compliance and resistance values and decreased linearly with the time constant (r² = 0.80, p < 0.001). The minimum alveolar pressure ranged from 15.5 ± 0.04 to 16.57 ± 0.04 cmH2O. Cross-flows between the simulated patients have been recorded in all the tested combinations, during both the inspiratory and expiratory phases. The simultaneous ventilation of two patients with one ventilator may be unable to match individual patient’s needs and has a high risk of cross-interference.

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“…Technical innovations have been proposed to individualize ventilator settings in each test-lung/patient, such as set inspiratory pressure, PEEP, and F I O 2 . These innovations include a one-way flow control valve at inspiratory and expiratory limbs in each test-lung/patient [ 13 ], a fixed pressure resistor regulator added at the inspiratory limb [ 32 ], a variable flow restrictor at the inspiratory limb, and a one-way valve at the expiratory limb [ 33 ], a flow restrictor on-way valve at the outlet of the ventilator [ 10 ], and bag-in-the box [ 23 ]. It should be noted that even though some of the interventions described above have been tested in a few patients [ 13 ], the experience is limited, they are complex to use and may generate further severe problems, as in case of an acute change in respiratory mechanics or gas exchange in one or two patients if the staff is not well trained.…”

Section: Discussionmentioning

confidence: 99%

“…Started before the current COVID-19 pandemic [3,21], it was stressed that simultaneous ventilation cannot support its use in mass causality because V T was too much variable across C-R conditions and largely dependent on changes in compliance [3]. Since then, the current COVID-19 pandemic prompted additional bench studies to extend these previous results and proposed solutions to try to overwhelm some related issues [9,12,[22][23][24][25][26][27][28][29][30][31][32][33][34] (Table 5).…”

Section: Discussionmentioning

confidence: 99%

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

et al. 2021

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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.

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Regulating inspiratory pressure to individualise tidal volumes in a simulated two-patient, one-ventilator system

Cited by 10 publications

References 11 publications

Assessment of a splitter for protective dual-patient ventilation in patients with acute respiratory distress syndrome

Assessment of a splitter for protective dual-patient ventilation in patients with acute respiratory distress syndrome

Sharing Mechanical Ventilator: In Vitro Evaluation of Circuit Cross-Flows and Patient Interactions

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

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