Mechanical Ventilation

Mar 242018
 
High-Flow Nasal Cannula, Work of Breathing & Mechanical Power: is there benefit?

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]

Mar 122018
 
Is There Synergy between PEEP & Prone Position in ARDS?

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]

Mar 022018
 
Corticosteroids do help in sepsis: ADRENAL trial

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]

Jan 202018
 
Prone positioning for severe ARDS advised by major societies

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]

Dec 262017
 
ICU Physiology in 1000 Words: Visualizing Heart-Lung Interaction

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]

Dec 142017
 
Sedation interruptions were even more helpful in surgical patients

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]

Dec 022017
 
A Great Lecture on Applied Respiratory Physiology

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]

Oct 202017
 
Pain Control and Sedation in Mechanically Ventilated Patients: Review

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]

Oct 192017
 
ICU Physiology in 1000 Words: Fighter Pilots!

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]

Sep 292017
 
State-of-the-ART Trial: Do Recruitment Maneuvers & Higher PEEP Raise Mortality?

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]

Sep 142017
 
ICU Physiology in 1000 Words: High Flow Oxygen Therapy

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]

Aug 302017
 
An Illustrated Guide to the Phases of ARDS: Implications for management

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]

Aug 202017
 
In ARDS, substandard ventilator care is the norm, not the exception

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]

Jul 292017
 
ICU Physiology in 1000 Words: IVC Collapse, Revisited – Part 2

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]

Jul 222017
 
ICU Physiology in 1000 Words: IVC Collapse, Revisited – Part 1

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]

Jul 082017
 
Intubation during CPR was associated with worse survival and brain health

“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]

May 072017
 
Video laryngoscopy was no better than directly intubating in the ICU, and may have been worse (MACMAN)

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]

Apr 222017
 
ICU Physiology in 1000 Words: Weaning-Induced Cardiac Dysfunction & the Passive Leg Raise

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]

Mar 202017
 
ICU Physiology in 1000 Words: Heliox & Mechanical Power

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]

Mar 012017
 
Are ventilator-associated pneumonia rates plummeting, or unchanged?

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]