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]
Jon-Emile S. Kenny MD [@heart_lung] “To believe in medicine would be the height of folly, if not to believe in it were not a greater folly still.” -Proust A 32 year old man with no past medical history save for a BMI of 51 is admitted with severe acute pancreatitis following a large intake of [… read more]
Jon-Emile S. Kenny MD [@heart_lung] That high flow oxygen applied via nasal cannula lends itself to treating hypoxemic respiratory failure may be obvious. With adequate heat and humidification, oxygen can be employed relatively comfortably at very high flow rates – upwards of 60 L/min – to the nares. At such rates, the effort of the [… read more]
Jon-Emile S. Kenny MD [@heart_lung] with illustrations by Carla M. Canepa MD “Our life consists partly in madness, partly in wisdom: whoever writes about it merely respectfully and by rule leaves more than half of it behind.” -Montaigne Marking the 50 year anniversary of the first description of the adult respiratory distress syndrome – later [… read more]
Jon-Emile S. Kenny MD [@heart_lung] Please read part 1 and view the vodcast on inferior vena cava collapse prior to reading below; this post seeks to explain the interesting findings of Juhl-Olsen & colleagues [1] as well as provide a physiological rationale to Dr. Marik’s comments on my vodcast; there is a new explanatory animation [… read more]
Jon-Emile S. Kenny MD [@heart_lung] Three years ago I wanted to share my physiology website heart-lung.org; I needed a topic to stoke some interest, so I sent a brief essay to Matt here at pulmccm.org. In it, I briefly described inspiratory IVC collapse and its relationship to volume status and volume responsiveness. With this, the [… read more]
Jon-Emile S. Kenny MD [@heart_lung] Briefly, part 1 of this reflection on the mean systemic filling pressure [Pmsf] considered an analogy for volume status as the vastness of an ocean beyond the hull of a leaking ship; I argue that looking only inside the hull of the ship cannot tell you the volume of the [… read more]
Jon-Emile S. Kenny MD [@heart_lung] It’s 4 in the morning; I am somewhere between Riga and Stockholm. The moon is full and bright and rippling across the black, Baltic Sea. This warm, June darkness is cut like onyx by deep vibrations of a cruise ship and its collections of giggling Swedes; they karaoke ‘Spaceman’ by [… read more]
Jon-Emile S. Kenny MD [@heart_lung] Reminder: Help me with my master’s thesis! Please complete a learning module, and fill out this exceptionally brief survey! Perhaps the landmark trial elaborating an evolving cardiac dysfunction during the spontaneous breathing trial [SBT] is that of Lemaire and colleagues – published in 1988 [1]. One particularly memorable patient of [… read more]
Jon-Emile S. Kenny MD [@heart_lung] “Oh, East is East and West is West, and never the twain shall meet …” -Kipling Last year, I began adding physiology modules to heart-lung.org as a part of a Master’s Degree I am undertaking at the Karolinska Institutet in Stockholm, Sweden. The goal of these modules has been to encourage [… read more]
Jon-Emile S. Kenny MD [@heart_lung] Of the countless things taught to me by Dr. Chitkara at the Palo Alto VA Health Care System, one that sticks is the difference between density-dependent and viscosity-dependent airflow. He often used the chronic bronchitic suffering through the viscous, humid New York City summers as a teaching example. The importance [… read more]
Jon-Emile S. Kenny [@heart_lung] Read part 1 here Fluids and the Glycocaylx Critically-ill patients all likely have endothelial dysfunction to some degree. This perturbation in microvascular physiology may be underpinned by abnormal glycocalyx structure and function. Sepsis, trauma, surgery and ischemic insults are all known to disrupt the glycocalyx which will increase vascular fluid capacitance. [… read more]
Jon-Emile S. Kenny [@heart_lung] “To every (wo)man is given the key to the gates of heaven. The same key opens the gates of hell. And so it is with science.” -Richard Feynman A rich, frosty wind etherizes my face; this cool gust rips through the medieval, labyrinthine passageways of Old Stockholm like frayed edges of [… read more]
By Jon-Emile S. Kenny [@heart_lung] PulmCCM is not affiliated with or endorsed by the Society of Critical Care Medicine or the Surviving Sepsis Campaign. Click here to read the Surviving Sepsis Guidelines. “I am at the moment writing a lengthy indictment against our century. When my brain begins to reel from my literary labors, I make [… read more]
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