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] 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]
Will “therapeutic” hypothermia someday need to be renamed? After a rush of optimism surrounding small trials showing large benefits from hypothermia to 33° after out-of-hospital cardiac arrest, hospitals and intensivists flocked to provide hypothermia to all victims of cardiac arrest (in- or out-of-hospital). When the much more powerful TTM trial showed no benefit of deep cooling [… 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]
Therapeutic hypothermia after cardiac arrest was almost immediately accepted as standard care in 2002 when two smallish, unblinded randomized trials (n=77 and n=273) showed a significant benefit from hypothermia after out-of-hospital ventricular fibrillation cardiac arrest. Hospitals and their cardiac care units quickly adopted resource-intensive protocols to manage patients’ special needs while being cooled to an icy 33° [… read more]
Cooling kids to 33ºC after resuscitation from in-hospital cardiac arrest brought no benefits compared to fever prevention (maintenance at 36.8°C), in the large THAPCA randomized trial. After one year, survival was 39% with hypothermia and 36% with management of body temperature in the normal range. There were no differences in neurologic outcomes or any other [… 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]
By Jon-Emile S. Kenny [@heart_lung] When interpreting hemodynamic studies of drugs which – potentially – alter the resistance of the pulmonary vascular tree, we often turn to the calculated pulmonary vascular resistance [cPVR] as our guide. For instance, a vasopressor determined to increase the cPVR is wholly avoided in a patient with pulmonary arterial hypertension. We [… read more]
What’s the shelf life of human blood? Like the milk in your fridge, stored donated human blood has an expiration date: currently it’s 42 days, set by the FDA. But is fresher blood actually better? As with ordering wine by the glass, should patients about to be transfused blood ask for “whatever was opened most recently”? There’s [… read more]
By Jon-Emile S. Kenny [@heart_lung] “Major Major had been born too late and too mediocre. Some men are born mediocre, some men achieve mediocrity, and some men have mediocrity thrust upon them. With Major Major it had been all three …” -Joseph Heller In my younger days, parked on a bench overlooking Stanley Park, I sought [… read more]
By Jon-Emile S. Kenny [@heart_lung] “I want to be your medicine, I want to feed the sparrow in your heart …” -Kristian Matsson Case A 39 year old woman is admitted to the intensive care unit for hypotension, anuria and altered mentation despite 3 litres of intravenous lactated ringers infusion. She is febrile and found to [… read more]
The Rise of Mechanical Circulatory Support Devices What Critical Care Physicians Need to Know Felipe Teran-Merino M.D. Part 2 of 2 (read part 1) II. Main MCS devices used for emergency and short-term support Intra-Aortic Balloon Pump The oldest and simplest mechanical device is the intra-aortic balloon pump (IABP). Introduced in 1968, the IABP is still used as a [… read more]
The Rise of Mechanical Circulatory Support Devices What Critical Care Physicians Need to Know Felipe Teran-Merino M.D. Part 1 of 2 (read part 2) I. The failing pump and hemodynamic rationale for the use of MCS devices The rising field of mechanical circulatory support (MCS) offers a spectrum of therapies and devices with the potential to rescue patients [… read more]
Jon-Emile S. Kenny [@heart_lung] A 23 year old woman is admitted with severe abdominal pain following 5 days of profound non-bloody diarrhea and 72 hours of recalcitrant non-bloody emesis. She has lost 7 pounds in this time frame and has been unable to maintain oral hydration. Her eyes are sunken and her vital signs are [… read more]
Jon-Emile S. Kenny [@heart_lung] A 58 year old man with ethanol-related cirrhosis is admitted to the floor with anuria and a rising creatinine. Over the day, serial ultrasounds of his inferior vena cava [IVC] consistently reveal that it is diminutive and collapsing. He receives many liters of crystalloid without much change in his urine output. [… read more]
New oral anticoagulants like dabigatran, apixaban and rivaroxaban have advantages over warfarin: not requiring regular monitoring for efficacy; faster onset of action; shorter half-lives. Unlike warfarin, they’ve had the significant disadvantage of having no proven antidote for the bleeding that inevitably occurs when any anticoagulant is given to thousands of people. [lawsuits] Boehringer Ingelheim, makers [… read more]
Not long ago, doctors were taught that 6 months of anticoagulation was plenty for patients with unprovoked pulmonary embolism. That standard was never based on long-term outcomes studies. And as longer-range data started to come in — gulp — it was clear that large numbers of people treated with 6-month warfarin courses after unprovoked PE [… read more]
Direct thrombin inhibitors (DTIs) are anticoagulants (blood thinners) most often used as alternatives to heparin and warfarin. DTIs are approved by the FDA for prevention and treatment of venous thromboembolism (deep venous thrombosis and pulmonary embolism) and to prevent blood clots in people with atrial fibrillation. But multiple randomized trials suggest these widely used anticoagulants might cause heart [… read more]
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