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]
Stress-dose corticosteroids appear safe and generally beneficial in patients with septic shock undergoing mechanical ventilation, without improving survival. That’s the takeaway from the ADRENAL trial recently published in the New England Journal of Medicine. Investigators (led by the famed ANZICS collaborative) randomized 3,800 patients with septic shock requiring mechanical ventilation in 69 medical-surgical ICUs around the [… 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]
Most good medical intensive care units have incorporated interruptions in sedation (so-called ‘sedation vacations’) into standard care for patients receiving mechanical ventilation. Avoiding excessive sedation in general is believed to reduce prolonged mechanical ventilation in ICUs. However, there is surprisingly little data about effects of sedation (or over-sedation) on critically ill postoperative patients in 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]
Treating Pain in Mechanically Ventilated Patients Adult patients in the intensive care unit (ICU) frequently experience pain, resulting from acute and chronic illness as well the positioning and interventions standard to ICU care.1,2 Besides being ethical and humane, adequately treating pain prevents agitation and delirium in mechanically ventilated patients. There are also many physiologic responses to [… 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]
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]
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