Jon-Emile S. Kenny MD [@heart_lung] “What is REAL?” -Velveteen Rabbit A 42 year old woman with poorly-controlled type II diabetes is admitted with a severe soft tissue infection of her left lower extremity. She is hypotensive with altered sensorium and she is noted to have a rapidly progressing border of deep, crimson erythema and edema [… 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] “What is memory but a story about how we have lived?” -Mark Doty During the recent ‘Hospitalist and the Resuscitationist’ conference in Montreal, there were discussions around the hemodynamics of prone positioning as well as using venous Doppler as a hemodynamic metric. Much of this discussion was generated and driven [… 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] with illustrations by Carla M Canepa MD “Each time new experiments are observed to agree with the predictions, the theory survives and our confidence in it is increased; but if ever new observation is found to disagree, we have to abandon or modify the theory.” — Stephen Hawking A 47 [… 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]
Jon-Emile S. Kenny MD [@heart_lung] “The truth is rarely pure and never simple.” -Oscar Wilde In part 1, the crux of this ‘Great Lactate Debate’ was distilled into the unclear origin of the proton in the setting of ‘lactic acidosis.’ Is the [H+] secondary to biochemical work and ATP hydrolysis or is the proton from [… read more]
Jon-Emile S. Kenny MD [@heart_lung] “…. She was here on earth to grasp the meaning of its wild enchantment and to call each thing by its right name …” -Boris Pasternak Background Over the last half-decade, there has been a distinct shift in the approach to lactate elevation. The long-held belief that elevated serum lactate [… read more]
Jon-Emile S. Kenny MD [@heart_lung] “It’s these expressions, I never give, That keep me searching for a heart of gold … And I’m gettin’ old.” -Neil Young An 86 year old woman is admitted with progressive dyspnea and lower extremity edema. 8 months ago she received a trans-catheter aortic valve replacement (TAVR) for severe aortic [… read more]
Jon-Emile S. Kenny MD [@heart_lung] With the birth of ‘fluid responsiveness’ physiology [1], there has been a slow and solemn drumbeat ushering the central venous pressure [CVP] up the squeaking planks of the hemodynamic gallows [2, 3]. Despite this, a few years ago I made a humble defense of the central venous pressure. Importantly, I was [… 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] Background If venous pressure were always the downstream pressure of an artery, then when flow is zero, the arterial pressure should equal the venous pressure. For example, if one were to measure the coronary artery pressure and coronary sinus pressure at zero flow, their pressures should be equal. Yet, this [… 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]
Jon-Emile S. Kenny MD [@heart_lung] with illustrations by Carla M Canepa MD “… And you may ask yourself … well, how did I get here? … And you may tell yourself … my God! What have I done?” -David Byrne A 92 year old woman is transferred to the coronary care unit for treatment of pulmonary edema. She [… read more]
Jon-Emile S. Kenny MD [@heart_lung] In the last few weeks I have been contacted by curious clinical physiologists craving my conceptions of ‘venous excess’ [1]. These words will address this model, concisely and – I pray – clearly. The Myth of Venous Return The roots of venous excess took hold within the fertile soil of [… read more]
Jon-Emile S. Kenny MD [@heart_lung] with illustrations by Carla M. Canepa MD Pilots of high-performance, tactical fighter jets each have continuous positive airway pressure [i.e. CPAP] masks as a part of their flight suit. Strikingly, beyond the clinically-commonplace airway pressure of 5-15 cm of H2O, a fighter pilot may endure a mask-applied pressure of 90 [… read more]
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