In acute respiratory distress syndrome (ARDS), anyone with the keys to a ventilator knows low tidal volume ventilation (~6 mL/kg ideal body weight) is standard care. Low tidal volume ventilation can prevent or ameliorate ventilator-associated lung injury ; if early clinical trials represent current reality, one in 11 people with ARDS treated by low tidal volume ventilation could have their [… 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]
“Stop chest compressions for a minute while I intubate this patient!” That refrain must have been heard tens of thousands of times during CPR after cardiac arrest before 2010, when the American Heart Association’s (AHA) Advanced Cardiac Life Support (ACLS) guidelines advised resuscitation teams not to interrupt chest compressions to place advanced airways, unless a patient [… read more]
Video laryngoscopy provides beautiful close-up views of the larynx, by navigating a sensor past the tongue and pharyngeal tissues that can obstruct direct laryngoscopy views. These visual advantages led to its wide adoption by anesthesiologists, emergency physicians, and intensivists after video laryngoscopy’s introduction in the late 1990s. The intuition that better visualization must result in improved intubation rates — [… 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] 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]
In 2008 hospitals were informed they would no longer be paid for treating hospital acquired infections like ventilator associated pneumonia. Miraculously, the rates of VAP (self-reported by hospitals to the Centers for Disease Control and Prevention) fell dramatically by 60 to 70% between 2006 and 2012, to less than one VAP per 1,000 ventilator days [… read more]
By Scott Aberegg, MD, MPH Like many starry-eyed medical students, I was drawn to critical care because of the high stakes, its physiological underpinnings, and the apparent fact that you could take control of that physiology and make it serve your goals for the patient. On my first MICU rotation in 1997, I was so swept [… read more]
Oxygen is essential for life, but by forming superoxides and free radicals, supplemental oxygen can also inflict damage on lung and other body tissues. The sweet spot for oxygen delivery in critically ill patients is unknown, but increasing evidence suggests that when it comes to blood oxygen saturation during critical illness, “normal” levels might actually [… read more]
A new term has been coined by the Centers for Disease Control and Prevention, ventilator-associated events (VAEs)¹. In 2011, the CDC convened a working group composed of members of several stakeholder organizations to address the limitations of the definition of ventilator-associated pneumonia (VAP) definition². The organizations represented in the Working Group include: the Critical Care [… read more]
Jon-Emile S. Kenny MD [@heart_lung] Hemodynamic assessment, by any means, demands a shrewd familiarity with mechanical heart-lung interaction. The two ventricles communicate in series and in parallel; each ventricle’s pressure-volume characteristics and loading conditions pulsate between systole and diastole. And around the heart and pericardium lies the respiratory pump – the lungs within the thorax [… read more]
Every year, over a million people in the U.S. suffer respiratory failure requiring mechanical ventilation. They experience enormous catabolic stress, extended periods of inactivity, and usually go without their usual caloric intake. It’s no surprise that many are rendered profoundly debilitated by the experience. For many, this weakness and loss of muscle mass represents a second [… read more]
Jon-Emile S. Kenny [@heart_lung] “Truth is like the sun, its value wholly depends upon our being at a correct distance away from it.” -Hjalmar Söderberg The evening is invigorating; the Stockholm Marathon has been run and cobblestoned cafés, concealed within winding, narrowed side-streets are in the throes of summer’s end. I take a coffee and [… read more]
Jon-Emile S. Kenny [@heart_lung] While parts 1 and 2 of this trilogy considered the mechanical power applied to the lung skeleton and the effects of lung inhomogeneity [i.e. ‘stress raisers’], respectively; this final installment will draw the reader towards the pulmonary vasculature as a key mediator of ventilator induced lung injury [VILI]. That the pulmonary [… read more]
Jon-Emile S. Kenny [@heart_lung] Gattinoni and Quintel have, very recently, outlined their approach to managing the acute respiratory distress syndrome [ARDS] [1]. They argue that treatment of ARDS should minimize firstly, the mechanical power applied to the lungs – as described in part 1. Secondly, Gattinoni and Quintel note that, in the treatment of ARDS, [… read more]
Jon-Emile S. Kenny [@heart_lung] “Often, as new knowledge progresses, old knowledge is abandoned or forgotten.” -Luciano Gattinoni In a succinct and current treatise, Gattinoni and Quintel outline the modern management of the acute respiratory distress syndrome [ARDS] [1]. It is imperative, they reason, that treatment of ARDS minimizes firstly, the mechanical power applied to the [… read more]
Jon-Emile S. Kenny [@heart_lung] In part 2, I continue my commentary on this excellent review; part 1 may be found here. In this post I will consider patients with severe metabolic acidosis and those with right ventricular [RV] dysfunction and/or failure. Severe Metabolic Acidosis In patients with severe metabolic acidosis, alveolar ventilation tends to be maximal [… read more]
Jon-Emile S. Kenny [@heart_lung] To celebrate the birthday of Dr. Erin Hennessey [@ErinH_MD] – my former co-fellow and current Stanford intensivist-anesthesiologist – I will interpret a relatively recent and terrifically high-yield overview of physiologically challenging intubations. In this must-read survey, the authors highlight particularly troublesome intubations not from the classic, anatomical perspective, but from the [… read more]
Jon-Emile S. Kenny [@heart_lung] A recent study of applied respiratory physiology in the mechanically-ventilated, obese patient was published. The ubiquitous focus on lung protective ventilation with “low” [physiological] lung volumes, and low plateau pressure may leave the obese patient susceptible to respiratory embarrassment. Excess abdominal and chest wall weight affect each of the following: reduction [… read more]
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