Jon-Emile S. Kenny MD [@heart_lung] More than 20 years ago Amato and colleagues reported a significant mortality reduction in ARDS patients who had their ventilator settings guided by the pressure-volume [PV] curve [1]. The 28-day mortality reduction was profound – 71% versus 38% – in favour of the patients who had their positive end-expiratory pressure [… read more]
Jon-Emile S. Kenny MD [@heart_lung] “I am suffocated and lost when I have not the bright feeling of progression” -Margaret Fuller A recent letter and review in Critical Care have called for adoption of the ‘Open Lung Approach’ to patients with severe ARDS. More specifically, in refractory ARDS whilst prone, it is argued that esophageal [… read more]
In acute respiratory distress syndrome (ARDS), using pleural pressure to adjust positive end-expiratory pressure (PEEP) has long been considered a cumbersome but theoretically ideal technique to optimize ventilator management. Using esophageal pressure as a surrogate for pleural pressure can allow one to calculate and minimize the transpulmonary pressure gradient, elevations in which are the putative [… read more]
Jon-Emile S. Kenny MD [@heart_lung] The mechanical power applied to the lung is a risk factor for ventilator or ventilation-induced lung injury [VILI] [1-4]. But can the work done to the lung over time be homogenized into a single value? Could different components of the power equation carry different VILI risk beyond their mathematical inequalities [… read more]
Jon-Emile S. Kenny MD [@heart_lung] A few years ago I was intrigued by a new concept in Ventilator-Induced Lung Injury [VILI] – the mechanical power. I employed this paradigm, introduced by Gattinoni’s group, as an opening for the ‘ARDS Trilogy.’ Since then, I have also discussed this ‘ergotrauma’ in the context of helium-oxygen physiology and [… read more]
Jon-Emile S. Kenny MD [@heart_lung] In a recent and excellent open-access review, Gattinoni, Quintel and Marini ask which is worse, volutrauma or atelectrauma [1]? This concise review is an absolute must-read and forms the fabric from which this short article assembles. Last spring – in Montreal – I was asked a few questions about volutrauma [… read more]
Jon-Emile S. Kenny MD [@heart_lung] “Once had a love and it was a gas …” -Blondie Case A 56 year old professor returns from a hiking trip in the ‘Four Corners’ area of New Mexico. She was previously well and decided to rent a secluded desert cabin whilst writing a novel on the ethical obligations [… read more]
Extracorporeal membrane oxygenation (ECMO) is an accepted salvage therapy for severe acute respiratory distress syndrome (ARDS) after conventional mechanical ventilation with low tidal volumes, neuromuscular blockade and prone positioning have failed. ECMO has been proposed as the ultimate lung protection strategy for ARDS, because it bypasses the lungs entirely. So why shouldn’t it be first-line [… read more]
Jon-Emile S. Kenny MD [@heart_lung] “WANTED: Somebody to go back in time with me. This is not a joke …” -John Silveira Case A 78 year old man with known moderate-to-severe emphysema is extubated in the ICU; he was initially admitted with hypercapneic respiratory failure secondary to influenza pneumonia and pulmonary edema from the medical [… read more]
Jon-Emile S. Kenny MD [@heart_lung] with illustrations by Carla M. Canepa MD “For others, in spite of myself, from myself.” -Emmanuel Levinas Case A 52 year old man is admitted to the intensive care unit with bilateral pulmonary opacities, worsening gas-exchange and hypotension requiring peripherally-administered norepinephrine. His PaO2-to-FiO2 ratio is less than 100; he is [… read more]
Jon-Emile S. Kenny MD [@heart_lung] “One of the symptoms of an approaching nervous breakdown is the belief that one’s work is terribly important.” -Bertrand Russel I read with great interest a recent letter penned by Taylor and Camporota in response to an investigation on airway pressure release ventilation [APRV] by Zhou and colleagues. Their brief [… read more]
Jon-Emile S. Kenny MD [@heart_lung] Lung Stress in Pulmonary & Extrapulmonary ARDS Initially described in the late 1990s, the distinction between direct pulmonary insults [i.e. pulmonary ARDS] and indirect pulmonary insults [i.e. extra-pulmonary ARDS] is important [1]. Additionally, direct pulmonary injury such as gastric acid aspiration may have a different molecular phenotype from indirect, extra-pulmonary [… read more]
Jon-Emile S. Kenny MD [@heart_lung] In the previous segment, time constants [t] – and their limitations – were described as a lesson in applied respiratory physiology for setting T-Low and prediction of auto-PEEP in airway pressure release ventilation [APRV]. In this brief missive an alternative approach to titrating T-low is described and critiqued. As well, [… read more]
Jon-Emile S. Kenny MD [@heart_lung] While the lung in the throes of acute respiratory distress syndrome [ARDS] is shrunken, edematous and inflamed, a basic management maneuver is to ‘recruit’ lost pulmonary surface area. In other words, unfold alveolar-capillary units with the ventilator like a respirothoracic party horn. One ‘unconventional’ method of maximizing and maintaining lung [… read more]
Jon-Emile S. Kenny MD [@heart_lung] “The real process of education should be the process of learning to think through the application of real problems.” -John Dewey On April 18 & 19, 2018, I had the pleasure of participating in the inaugural conference “The Hospitalist and the Resuscitationist” in Montreal. The entirety of this meeting was [… read more]
Jon-Emile S. Kenny MD [@heart_lung] “I grow old … I grow old … I shall wear the bottoms of my trousers rolled.” -T. S. Eliot Background While it is tempting to isolate nasal high flow [NHF] into one’s cognitive schema for hypoxemia, NHF rightly deserves an esteemed position within one’s cerebral scaffolds for both hypercapnia [… read more]
Jon-Emile S. Kenny MD [@heart_lung] “… when you walk around a kitchen, you will say to yourself, this is interesting, this is grand, this is beautiful like Chardin.” -Marcel Proust Background Titration of positive end-expiratory pressure [PEEP] in the acute respiratory distress syndrome [ARDS] is achieved by a diverse assortment of practices undergirded by equally [… read more]
In case you missed it, major professional societies in critical care now strongly recommend prone positioning for patients with severe acute respiratory distress syndrome (ARDS), with a PaO2-to-FiO2 (P/F) ratio of ≤ 100. The recommendation marks a major shift in advised care for ARDS. Prone positioning improves ventilation-perfusion matching (transferring delivered oxygen into the bloodstream more [… read more]
Jon-Emile S. Kenny MD [@heart_lung] “Upward, not northward.” -E. A. Abbott A pressure chamber within a pressure chamber; the heart within the thorax. These are two pumps beating in-and-out of time, varying in physiology and pathophysiology between patients and within any one patient during the arc of an illness. As such, when we inspect the [… read more]
Jon-Emile S. Kenny MD [@heart_lung] -What is the world record for longest breath hold? -Why does the diagnosis of brain death require a rise in PaCO2 to at least 60 mmHg? -What minute ventilation can a human achieve? -What’s the difference between an elevated PaCO2 in someone who ‘won’t’ versus ‘can’t’ breathe? I’d like to [… read more]
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