Combined Ventilation of Two Subjects with a Single Mechanical Ventilator Using a New Medical Device: An In Vitro Study.

INTRODUCTION: The SARS-CoV-2 pandemic has created a sudden lack of ventilators. DuplicARⓇ is a novel device that allows simultaneous and independent ventilation of two subjects with a single ventilator. The aims of this study are (a) to determine the efficacy of DuplicARⓇ to independently regulate the peak and positive-end expiratory pressures in each subject, both under pressure-controlled ventilation and volume-controlled ventilation and (b) to determine the ventilation mode in which DuplicARⓇ presents the best performance and safety. MATERIALS AND METHODS: Two test lungs are connected to a single ventilator using DuplicARⓇ. Three experimental stages are established: (1) two identical subjects, (2) two subjects with the same weight but different lung compliance, and (3) two subjects with different weights and lung compliances. In each stage, the test lungs are ventilated in two ventilation modes. The positive-end expiratory pressure requirements are increased successively in one of the subjects. The goal is to achieve a tidal volume of 7 ml/kg for each subject in all different stages through manipulation of the ventilator and the DuplicARⓇ controllers. RESULTS: DuplicARⓇ allows adequate ventilation of two subjects with different weights and/or lung compliances and/or PEEP requirements. This is achieved by adjusting the total tidal volume for both subjects (in volume-controlled ventilation) or the highest peak pressure needed (in pressure-controlled ventilation) along with the basal positive-end expiratory pressure on the ventilator and simultaneously manipulating the DuplicARⓇ controllers to decrease the tidal volume or the peak pressure in the subject that needs less and/or to increase the positive-end expiratory pressure in the subject that needs more. While ventilatory goals can be achieved in any of the ventilation modes, DuplicARⓇ performs better in pressure-controlled ventilation, as changes experienced in the variables of one subject do not modify the other one. CONCLUSIONS: DuplicARⓇ is an effective tool to manage the peak inspiratory pressure and the positive-end expiratory pressure independently in two subjects connected to a single ventilator. The driving pressure can be adjusted to meet the requirements of subjects with different weights and lung compliances. Pressure-controlled ventilation has advantages over volume-controlled ventilation and is therefore the recommended ventilation mode.

A New Medical Device to Provide Independent Ventilation to Two Subjects Using a Single Ventilator: Evaluation in Lung-Healthy Pigs.

BACKGROUND: The global crisis situation caused by SARS-CoV-2 has created an explosive demand for ventilators, which cannot be met even in developed countries. Designing a simple and inexpensive device with the ability to increase the number of patients that can be connected to existing ventilators would have a major impact on the number of lives that could be saved. We conducted a study to determine whether two pigs with significant differences in size and weight could be ventilated simultaneously using a single ventilator connected to a new medical device called DuplicARⓇ. METHODS: Six pigs (median weight 12 kg, range 9-25 kg) were connected in pairs to a single ventilator using the new device for 6 hours. Both the ventilator and the device were manipulated throughout the experiment according to the needs of each animal. Tidal volume and positive end-expiratory pressure were individually controlled with the device. Primary and secondary outcome variables were defined to assess ventilation and hemodynamics in all animals throughout the experiment. RESULTS: Median difference in weight between the animals of each pair was 67% (range: 11-108). All animals could be successfully oxygenated and ventilated for 6 hours through manipulation of the ventilator and the DuplicARⓇ device, despite significant discrepancies in body size and weight. Mean PaCO2 in arterial blood was 42.1 ± 4.4 mmHg, mean PaO2 was 162.8 ± 46.8 mmHg, and mean oxygen saturation was 98 ± 1.3%. End-tidal CO2 values showed no statistically significant difference among subjects of each pair. Mean difference in arterial PaCO2 measured at the same time in both animals of each pair was 4.8 ± 3 mmHg, reflecting the ability of the device to ventilate each animal according to its particular requirements. Independent management of PEEP was achieved by manipulation of the device controllers. CONCLUSION: It is possible to ventilate two lung-healthy animals with a single ventilator according to each one's needs through manipulation of both the ventilator and the DuplicARⓇ device. This gives this device the potential to expand local ventilators surge capacity during disasters or pandemics until emergency supplies can be delivered from central stockpiles.

The Kawashima Operation With Simultaneous Preparation for Transcatheter Fontan-Kreutzer Completion.

Patients with functionally single ventricle and interrupted inferior vena cava may develop progressive cyanosis soon after the Kawashima operation. Therefore, early redirection of the hepatic venous return to the pulmonary circulation is recommended. To avoid performing an early redo sternotomy, we propose to prepare these patients for the interventional Fontan-Kreutzer at the time of the Kawashima operation using a technical modification of the approach reported by Prabhu and coworkers in 2017. The technique described here uses an expanded polytetrafluoroethylene conduit interposed between the hepatic veins and the right pulmonary artery. This graft is everted and divided into two portions with a pericardial patch. The lower one is widely opened and anastomosed side-to-side to the atrium. A few months after the operation, percutaneous Fontan-Kreutzer completion can easily be performed using covered stents to open the patch and at the same time close the opening between the conduit and the atrium.

The matter of "unbalance" in right dominant atrioventricular septal defect.

Unbalance in atrioventricular septal defect can be found in more than one anatomic level and in different degrees at each level. The definition of "unbalance" has historically been focused in comparing the dimensions of main cardiac structures, such as the atrioventricular valve and the ventricles. However, the hemodynamic aspects of unbalance need to be considered as having, at least, similar relevance. New concepts and already described parameters must be combined and understood as a whole to help the surgical decision-making process.

Modified In Situ Pericardial Rerouting Technique for Scimitar Syndrome Repair.

Scimitar syndrome repair represents a challenge due to the high incidence of postoperative pulmonary venous obstruction associated with classic surgical strategies. In situ pericardial rerouting technique has been considered a promising alternative approach due to its simplicity and excellent midterm results. Access to the left atrium can be difficult in young patients with severe dextrocardia and hypoplastic right lung. We describe a modification of the original rerouting technique in which the atrial septum is repositioned in order to create a wide opening in the lateral aspect of the left atrium and ensure an adequate size of the reconstructed pathway.

Feasibility of Biventricular Repair in Right Dominant Unbalanced Atrioventricular Septal Defect: A New Echocardiographic Metric to Refine Surgical Decision-Making.

BACKGROUND: Unbalanced forms of atrioventricular septal defect continue to be challenging and present poor surgical outcomes. Echocardiographic indicators such as atrioventricular valve index, right ventricle/left ventricle inflow angle, and size of the ventricular septal defect have been identified as relevant discriminators that may guide surgical strategy. Our purpose is to describe another metric to refine surgical decision-making. METHODS: We outline a geometrical description of the anatomic features of atrioventricular septal defect and describe equations that help explain the interplay between the main echocardiographic variables. RESULTS: A new metric called "indexed ventricular septal defect" is defined as the size of the defect in relation to the valve diameter. We derive a final equation relating this index with the atrioventricular valve index and the right ventricle/left ventricle inflow angle. In the light of that equation, we discuss the interdependence of variables and employ data from a Congenital Heart Surgeons' Society study to set the limits of the new index. CONCLUSION: Combined use of indexed ventricular septal defect and atrioventricular valve index might help clarify surgical decision-making in patients with mild and moderate unbalance (modified atrioventricular valve index between 0.2 and 0.39). For indexed ventricular septal defect smaller than 0.2, biventricular repair may be recommended. Between 0.2 and 0.35, this strategy could probably be achieved depending on other factors. However, other strategies should be considered for those patients showing an indexed ventricular septal defect between 0.35 and 0.5. For values above 0.5 to 0.55, univentricular palliation might be a reasonable strategy.