Background: The COVID-19 pandemic crisis has led to an international shortage of mechanical ventilation. Due to this shortfall, the surge of increasing number of patients to limited resources of mechanical ventilators has reinvigorated the interest in the concept of split ventilation or co-ventilation (ventilating more than one patient with the same ventilator). However, major medical societies have condemned the concept in a joint statement for multiple reasons. Materials and Methods: In this paper, we will describe the history of the concept, what is trending in the literature about it and along our modification to ventilate two patients with one ventilator. We will describe how to overcome such concerns regarding cross contamination, re-breathing, safely adjusting the settings for tidal volume and positive end expiratory pressure to each patient and how to safely monitor each patient. Main results: Our experimental setup shows that we can safely ventilate two patients using one ventilator. Conclusion: The concept of ventilating more than one patient with a single ventilator is feasible especially in crisis situations. However, we caution that it has to be done under careful monitoring with expertise in mechanical ventilation. More research and investment are crucially needed in this current pandemic crisis.

This is a case of Acute Respiratory Distress Syndrome managed using esophageal balloon catheter to adjust inspiratory pressure and positive end expiratory pressure according to the inspiratory and expiratory transpulmonary pressures. There are no studies that examine the transpulmonary pressures in airway pressure release ventilation (APRV). We aimed to test the feasibility of using the esophageal balloon in the nonconventional mode of APRV. All pressures were observed when switching the mode from a pressure-controlled mode to APRV using the same inspiratory pressure and using various incremental release times (TLow)to calculate the expiratory transpulmonary pressure. At all TLow levels the transpulmonary pressure at end exhalation was in the negative value indicating alveolar collapse. A larger study is needed to confirm our findings and to help guide setting APRV.

Background: Quantification of the patient’s respiratory effort during mechanical ventilation is very important, and calculating the actual muscle pressure (Pmus) during mechanical ventilation is a cumbersome task and usually requires an esophageal balloon manometry. Airway occlusion pressure at 100 milliseconds (P0.1) can easily be obtained non-invasively. There has been no study investigating the association between Pmus and P0.1. Therefore, we aimed to investigate whether P0.1 correlates to Pmus and can be used to estimate actual Pmus Materials and Methods: A bench study using lung simulator (ASL 5000) to simulate an active breathing patient with Pmus from 1 to 30 cmH2O by increments of 1 was conducted. Twenty active breaths were measured in each Pmus. The clinical scenario was constructed as a normal lung with a fixed setting of compliances of 60 mL/cmH2O and resistances of 10 cmH2O/l/sec. All experiments were conducted using the pressure support ventilation mode (PSV) on a Hamilton-G5 ventilator (Hamilton Medical AG, Switzerland), Puritan Bennett 840TM (Covidien-Nellcor, CA) and Avea (CareFusion, CA). Main results: There was significant correlation between P 0.1 and Pmus (correlation coefficient = - 0.992, 95% CI: - 0.995 to -0.988, P-value<0.001). The equation was calculated as follows: Pmus = -2.99 x (P0.1) + 0.53 Conclusion: Estimation of Pmus using P 0.1 as a substitute is feasible, available, and reliable. Estimation of Pmus has multiple implications, especially in weaning of mechanical ventilation, adjusting ventilator support, and calculating respiratory mechanics during invasive mechanical ventilation. Keywords: P 0.1, Inspiratory occlusion pressure, WOB, Esophageal balloon, mechanical ventilators, respiratory failure Keywords: P 0.1, P mus, Inspiratory occlusion pressure, WOB, Esophageal balloon, mechanical ventilators, respiratory failure

Background There has been an exponential increase in modes of mechanical ventilation over the last couple decades. With this increase, there have been paucity of evidence of which mode is superior to others or much guidance to use a mode in different disease status causing respiratory failure. Methods: An international survey of six questions was posted on the “society of mechanical ventilation” website and advertised on social media over the period of four months. This is a descriptive study, results are presented in two different ways. First as the total modes used and secondly, per the geographical areas as the preferred mode, mode used mostly in ARDS, COPD, and Spontaneous weaning trials. Results: Conventional older modes, Volume-controlled and Pressure-controlled ventilation were used significantly more in general and in different disease states irrespective of geographical location. Four other modes were used almost equally in all disease states irrespective of geographical location. Pressure support ventilation was the most common mode used during the spontaneous breathing trial. Conclusion: There was large heterogenicity of modes used between clinicians in general, in different disease states and in between different international geographical locations. Mechanical ventilation modes utilization varies widely and remains a personal preference with no consensus between clinicians globally. Keywords: Modes of mechanical ventilation, ARDS, COPD, SBT, survey

Figure: Waveforms for a patient undergoing mechanical ventilation with volume controlled mode. Tidal Volume of 500 ml, PEEP 15, Constant inspiratory flow of 45 l/min A: Airway pressure in cmH2O, B: Esophageal pressure in cmH2O, C: Trans-pulmonary pressure in cmH2O, D: Flow in l/min, E: Tidal volume in ml Red dashed horizontal line: values at end of expiratory occlusion maneuver, White solid horizontal line: values at end of inspiratory occlusion maneuver, Green dashed horizontal line: values during peak inspiratory pressure.