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 untoward respiratory embarrassment. Excess abdominal and chest wall weight affect each of the following: [… read more]
By Jon-Emile S. Kenny [@heart_lung] The problem with the lung in the acute respiratory distress syndrome [ARDS] is not that it is stiff, but rather, that it is small [1]. In the 1980s, CT scans of the lungs of patients with ARDS revealed that the functional lung was attenuated in size and that dependent densities [… read more]
Everyone agrees that providing adequate nutrition in critical illness is vitally important. The problem is, no one knows for sure what “adequate” means. Caloric targets are not based on evidence from randomized trials with meaningful clinical outcomes. They emerge as consensus from educated guesses by researchers conducting physiology studies. One camp believes that extra calories should [… read more]
Noninvasive ventilation (NIV), often referred to by the trade name “BiPAP®,” can prevent intubation and save lives in patients with COPD exacerbations or pulmonary edema due to heart failure. Its proven benefits and low risk have led to NIV being used for patients in respiratory failure in virtually every acute care setting in the developed [… read more]
There’s always been doubt about the efficacy of the numerous “ventilator bundles” hospitals use to prevent ventilator-associated pneumonia (VAP). A provocative new analysis concludes that none of these methods save lives — except the one that almost no ICUs are using today. Healthcare associated pneumonias (HAP), especially ventilator-associated pneumonias (VAP), are associated with increased mortality, excess antibiotic use, lengthened hospital [… read more]
The fewer patients an ICU nurse has to juggle, the better those patients’ chances of making it out of the hospital alive, according to a large observational study published in Critical Care Medicine. Data from the large EPIC II study suggested that two patients per nurse may be too many for safe, high-quality critical care. Nurse-to-patient [… read more]
Thoracentesis for pleural effusion — that is, inserting a long needle between someone’s ribs to drain a fluid collection from the chest — has always come with a scary menu of potential risks, including pneumothorax, hemothorax and pulmonary edema. A new study reports a low complication rate from thousands of thoracenteses. But debate will remain whether the safety results — achieved [… read more]
Image: Airwaycam Endotracheal intubation is a routine but high-stakes maneuver, performed uneventfully thousands of times daily throughout the developed world. In the U.S., elective (routine) intubation is almost exclusively the domain of anesthesiologists, who become masters of the technique through thousands of iterations throughout training and their careers. The vast majority of these intubations take [… read more]
Subglottic suctioning can prevent ventilator-associated pneumonia (VAP), but much of the research showing its benefits was performed prior to wide adoption of the so-called “VAP bundle,” widely believed to reduce VAP incidence. This led some to question any additive benefits of subglottic suctioning. Authors of a new randomized trial found that subglottic suctioning also reduced ventilator-associated pneumonia incidence in a [… read more]
Stroke Volume Variation and the Concept of Dose-Response Jon-Emile S. Kenny M.D. Awareness of the undulating pattern of an arterial line tracing is high amongst health professionals in the intensive care unit; certainly this is an aftereffect of a cacophony of studies and reviews pertaining to pulse pressure variation and fluid responsiveness in the operating [… read more]
Feeding patients enterally (nasogastric or nasojejunal tube feedings) has been the standard of care for critically ill patients, based on weak evidence that it reduces infection rates; hence the adage “feed the gut, if you can.” That last caveat is included because so many critically ill patients have gastric motility impairment (with inability to achieve [… read more]
ICU Physiology in 1,000 Words “The Hemodynamics of Prone” by Jon-Emile S. Kenny MD A physiological maelstrom has recently swirled about the hemodynamic effects of the prone position in severe ARDS [1-5]; but how exactly does this maneuver alter the cardiovascular system? A good approach to this problem is a Guytonian one whereby we consider [… read more]
Have you heard of ventilator-associated events (VAEs)? Like it or not, this neologism of healthcare-speak is coming to an ICU near you soon. Here’s the lowdown on VAEs and why they matter to the practicing intensivist. What are Ventilator-Associated Events? Ventilator-associated events are an invention of the Centers for Disease Control and Prevention (CDC), created in [… read more]
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