Design of a flow modulation device to facilitate individualized ventilation in a shared ventilator setup.

This study aims to resolve the unmet need for ventilator surge capacity by developing a prototype device that can alter patient-specific flow in a shared ventilator setup. The device is designed to deliver a predictable tidal volume (VT), requiring minimal additional monitoring and workload. The prototyped device was tested in an in vitro bench setup for its performance against the intended use and design criteria. The ventilation parameters: VT and airway pressures, and ventilation profiles: pressure, flow and volume were measured for different ventilator and device settings for a healthy and ARDS simulated lung pathology. We obtained VTs with a linear correlation with valve openings from 10 to 100% across set inspiratory pressures (IPs) of 20 to 30 cmH2O. Airway pressure varied with valve opening and lung elastance but did not exceed set IPs. Performance was consistent in both healthy and ARDS-simulated lung conditions. The ventilation profile diverged from traditional pressure-controlled profiles. We present the design a flow modulator to titrate VTs in a shared ventilator setup. Application of the flow modulator resulted in a characteristic flow profile that differs from pressure- or volume controlled ventilation. The development of the flow modulator enables further validation of the Individualized Shared Ventilation (ISV) technology with individualization of delivered VTs and the development of a clinical protocol facilitating its clinical use during a ventilator surge capacity problem.

Individualized mechanical ventilation in a shared ventilator setting: limits, safety and technical details.

The COVID-19 pandemic has resulted in an increased need for ventilators. The potential to ventilate more than one patient with a single ventilator, a so-called split ventilator setup, provides an emergency solution. Our hypothesis is that ventilation can be individualized by adding a flow restrictor to limit tidal volumes, add PEEP, titrate FiO2 and monitor ventilation. This way we could enhance optimization of patient safety and clinical applicability. We performed bench testing to test our hypothesis and identify limitations. We performed a bench testing in two test lungs: (1) determine lung compliance (2) determine volume, plateau pressure and PEEP, (3) illustrate individualization of airway pressures and tidal volume with a flow restrictor, (4a) illustrate that PEEP can be applied and individualized (4b) create and measure intrinsic PEEP (4c and d) determine PEEP as a function of flow restriction, (5) individualization of FiO2. The lung compliance varied between 13 and 27 mL/cmH2O. Set ventilator settings could be applied and measured. Extrinsic PEEP can be applied except for settings with a large expiratory time. Volume and pressure regulation is possible between 70 and 39% flow restrictor valve closure. Flow restriction in the tested circuit had no effect on the other circuit or on intrinsic PEEP. FiO2 could be modulated individually between 0.21 and 0.8 by gradually adjusting the additional flow, and minimal affecting FiO2 in the other circuit. Tidal volumes, PEEP and FiO2 can be individualized and monitored in a bench testing of a split ventilator. In vivo research is needed to further explore the clinical limitations and outcomes, making implementation possible as a last resort ventilation strategy.

Enhanced Recovery After Revisional Bariatric Surgery: a Retrospective Study of 321 Patients with Laparoscopic Conversion of Failed Gastric Banding or Failed Mason Gastroplasty to Roux-en-Y Gastric Bypass.

PURPOSE: With the rising incidence of failed bariatric procedures, the importance of revisional surgery has been increasing. These revisional procedures come with a higher risk of complications leading to longer hospital stays. We believe though that enhanced recovery after revisional bariatric surgery is possible and needs to be advocated. MATERIALS AND METHODS: We retrospectively analyzed our laparoscopic conversions of failed gastric banding and failed Mason gastroplasty to Roux-en-Y gastric bypass. A total of 321 patients was included in the study, from February 2010 until December 2019. The primary endpoints were length of stay (LoS), in-hospital complication rate, and early readmission rate (< 30 days). Logistic regression was used to investigate the impact of several independent variables on complication and readmission rates. RESULTS: Fifty-four patients were male and 267 female. The mean age was 44.2 years and mean BMI at the time of conversion was 37.9 kg/m2. We converted 273 failed adjustable gastric bandings (85,0%) and 48 failed Mason gastroplasties (15.0%). The main reason for conversion was the recurrence of obesity. A mean LoS of 2.10 days was calculated. We had an overall in-hospital complication rate of 3.73% and the overall early readmission rate was 3.43%. The odds ratio for LoS on early readmission is 1.52 (p=0.0079; CI 95% [1.12-2.07]). CONCLUSION: The above data imply that the implementation of advanced ERAS principles for revisional surgery in our center is safe and does not lead to a higher risk of early readmission.