55. The Autumn Ghost

We are excited to bring you a special episode where we are joined by author Dr. Hanna Wunsch and will discuss her book, “The Autumn Ghost: How the Battle Against a Polio Epidemic Revolutionized Modern Medical Care.

Meet our Guests

Dr. Hannah Wunsch a Professor of Anesthesiology and Critical Care Medicine at the University of Toronto and is an intensivist at Sunnybrook Hospital. Hannah completed her medical training at Washington University School of Medicine and  received a Master’s Degree in Epidemiology from the London School of Hygiene and Tropical Medicine. She completed her anesthesia residency and critical care fellowship at Columbia University in New York and was on faculty there for 6 years prior to moving to Toronto. The Autumn Ghost is her first book.

In The Autumn Ghost, Dr. Hannah Wunsch shares the story of the polio epidemic in the autumn of 1952 in Copenhagen. She masterfully tells the story of how specialties came together to advance mechanical ventilation and intensive care units, and connects history to modern day medicine.

39. Fellows’ Case Files: Indiana University

Join us as we head to Indiana University! Listen in as we discuss another great case and hear teaching points from our amazing guests.

Meet our Guests


Parth Savsani is currently an internal medicine resident at Indiana University School of Medicine. He received his undergraduate degree from the University of Wisconsin-Madison and his medical degree from the University of Illinois College of Medicine. He enjoys medical education and was selected to be the VA chief resident next year.

Maria Srour is a Pulmonary and Critical Care Fellow at Indiana University School of Medicine. She completed her internal medicine residency at Saint Louis University where she was also a chief resident, and received her medical degree from IU. She works in global health to improve care for sepsis patients in low resources settings, and is currently pursuing her MPH.

Laura Hinkle is a Indiana University die hard and has been there from her since medical school through residency and fellowship, and is now an Assistant Professor of Clinical  Medicine and the Associate Program Director for the Pulmonary and Critical Care Medicine Fellowship. She will be taking over as the Program Director July 1, 2023. She is a dedicated educator and is the Key Clinical Educator for Pulmonary and Critical Care, and the Director of the Clinical Transitions Curriculum.  Additionally, she is working on a Master’s Degree in Education through the University of Cincinnati. 

Case Presentation

A male in her early 60s is transferred from a neighboring facility with a 1 week history of fatigue and lethargy. Three days prior to presentation he developed dyspnea and increased weakness with a near fall at home. HIs family also reported recent fevers, chills, dyspnea, and diarrhea. On his way to seek evaluation, he developed slurred speech without any other focal abnormalities.

Additional information is summarized as below:

Follow along our episode to hear the final diagnosis and key teaching points from the case!

Radiology Rounds – 4/11/2023

For “#RadiologyRounds” today, we won’t be looking at any imaging, but we’ll be looking at some vent wave forms and examining dysynchrony! This is a re-booted @david_furfaro Tweetorial. I hope you enjoy and this is an open invitation for all dysynchrony waveforms!

A 40s M is intubated for ARDS. In order to maintain lung protective ventilation, he was on high does of propofol, fentanyl and midazolam. His sedation is being weaned slightly now, and the RN calls for vent dysynchrony. His ventilator looks like this

Before delving into the type of dysynynchrony and management, based on these waveforms what is actually happening? Note: when we say “exhales” or “inhales” I am referring to the mechanical, vent-driven breaths

Let’s take a look at the waveforms and identify the phase of breathing. This is VC with a square flow waveform, so as a set volume is delivered, the flow is at a constant rate, and the pressure is measured. Expiration is about 2x as long as inspiration (determined by I time or flow rate)

With a passive patient (no dysynchrony) after inspiration, the volume curve should show a smooth decrease with exhalation, the pressure curve should flatten to the set PEEP, and the flow will be negative and gradually return to 0 as the patient exhales

In our case, you can see simultaneous dysynchrony in all three waveforms during exhalation (red arrows) vs normal (orange lines). There is a pressure negative deflection; the flow quickly rises to 0 before returning to negative; and the volume curve plateaus as exhalation pauses

Putting this together, it means that during expiration there is an inspiratory effort. The patient is trying to inhale, which causes a negative pressure deflection, and a pause in air flowing out of the lungs. If this effort triggered a breath, there could be breath stacking. Notice that the same pattern occurs after every breath, and clinically we said the patient was still heavily sedated. This combination of findings is a type of dysynchrony called REVERSE TRIGGERING or ENTRAINMENT.

You could consider whether this dysynchrony was an ineffective effort, but the trigger sensitivity was low, and the pattern and consistent timing after inspiration is more consistent with reverse triggering.

The change in pressure and flow of a ventilator-initiated, mandatory breath stimulates an inspiratory effort from the patient. Theories differ on if this is mediated by the diaphragm or central respiratory center. This can start during the ventilator-delivered breath, or afterwards in exhalation, as with our patient.

Reverse triggering often occurs in heavily sedated patients, and is defined by a stable, repetitive pattern (i.e. it is not voluntary, but reflex mediated). It can also occur in anoxic brain injury. Treating it involves breaking the pattern and avoiding harmful therapies. It can even be induced in healthy patients but this is much less clinically relevant, and is rare.

DO NOT just increase the trigger sensitivity of the vent. This can stop breath stacking but does not prevent dysynchrony and it can cause harmful changes in transpulmonary pressure. For this patient, sedation was lightened slightly, and the respiratory rate decreased and the pattern of reverse triggering ultimately broke without the need for paralysis.

35. The Future of ARDS Research Roundtable

We are extremely excited for another PulmPEEPs Roundtable table discussion today. We have spent multiple episodes talking about different aspects of ARDS and respiratory failure. Today, multiple expert guests return, as well as a new guest to the show, to discuss the future of ARDS research. This is a can’t miss discussion that is so jam-packed with pearls you’ll have to listen twice!

Meet Our Guests

Carolyn Calfee is a Professor of Medicine and Anesthesia at the University of California, San Francisco. She is a world-renowned ARDS researcher and has authored multiple landmark studies in the field. She previously joined us for a discussion on ARDS precision medicine and phenotypes.

Ewan Goligher is an Assistant Professor at the University of Toronto and University Health Network. He has published many practice-changing papers in ARDS. These have included prospective studies and some fantastic retrospective analyses that have fundamentally shaped our interpretation of trial results.  He previously came on the show discussing lung and diaphragm protection.

Sarina Sahetya is an Assistant Professor of Medicine at Johns Hopkins. She is a funded researcher in ARDS and respiratory physiology and has published multiple studies on lung protection and ARDS. She last helped us understand how to titrate PEEP in ARDS.

Matthew Semler is an Assistant Professor of Medicine and Biomedical Informatics at Vanderbilt University Medical Center, where he is also the Associate MICU Director and the co-director of the Inpatient Division of the Learning Healthcare System at Vanderbilt. Through his role as Chair of the Steering Committee for the Pragmatic Critical Care Research Group, he has helped lead more than two dozen randomized trials leading to multiple high-impact publications.

Radiology Rounds – 1/31/23

For today’s #RadiologyRounds we have a combined Radiology and Ventilator imaging rounds! You’re in the ICU caring for a young patient on a ventilator when you are called to the bedside for a desaturation.

You perform an inspiratory hold and see that the PIP, plateau, and difference between peak and plateau have all increased. On exam you hear bilateral mechanical breath sounds anteriorly. You order a CXR and the student asks a question about the waveforms

There are pressure deviations corresponding to the flow deviations.

There is no clear patient effort The fact that the PIP and plat have changed makes water in the tubing or cardiac oscillations less likely.

You think this is mucus, with a plug ball-valving in a bronchus

The CXR arrives and shows right lower lobe collapse.

A bedside bronchoscopy is performed with large mucus plugs suctioned out of the RLL and RML. Afterward, the patient’s oxygenation is improved, the flow deviations resolve, and the plateau pressure drops to 19

33. Lung and Diaphragm Protective Ventilation Roundtable

Today the PulmPEEPs are discussing Lung and Diaphragm Protective Ventilation with two experts in the field. We are joined by Dr. Jose Dianti and Dr. Ewan Goligher.

Meet Our Guests

Dr. Jose Dianti is a clinical and research fellow at the University of Toronto and University Health Network. He completed his residency in Critical Care and worked as a critical care attending previously at the Hospital Italiano in Buenos Aires, Argentina. He is particularly interested in ventilator induced lung injury and personalized ventilation strategies. Dr. Ewan Goligher is an Assistant Professor at the University of Toronto and University Health Network, and is a world renowned researcher in the mechanisms of ventilator induced lung and diaphragm injury.

7. Top Consults: Severe Asthma Exacerbation

We are excited to bring you another episode in our Pulm PEEPs Top Consults series! Kristina Montemayor and David Furfaro, are joined by Sandy Zaeh to discuss the assessment and management of a patient with a severe asthma exacerbation. We’ll follow a consult patient from the emergency department to the ICU, and cover everything from the physiology of pulsus paradoxus in asthma to how to manage the ventilator in status asthmaticus. Listen today and please send any questions our way on Twitter @pulmPEEPS.

Meet Our Guests

Sandy Zaeh is an Instructor of Medicine and Pulmonary & Critical Care Medicine physician at Yale School of Medicine.

Key Learning Points

References and links for further reading

  1. Chung KF, Wenzel SE, Brozek JL, et al. International ERS/ATS guidelines on definition, evaluation and treatment of severe asthma. European Respiratory Journal. 2014;43(2):343-373. doi:10.1183/09031936.00202013
  2. Rodrigo GJ, Rodrigo C, Hall JB. Acute asthma in adults: a review. Chest. 2004;125(3):1081-1102. doi:10.1378/chest.125.3.1081
  3. Godwin HT, Fix ML, Baker O, Madsen T, Walls RM, Brown CA. Emergency Department Airway Management for Status Asthmaticus With Respiratory Failure. Respir Care. 2020;65(12):1904-1907. doi:10.4187/respcare.07723
  4. Althoff MD, Holguin F, Yang F, et al. Noninvasive Ventilation Use in Critically Ill Patients with Acute Asthma Exacerbations. Am J Respir Crit Care Med. 2020;202(11):1520-1530. doi:10.1164/rccm.201910-2021OC
  5. Brenner B, Corbridge T, Kazzi A. Intubation and Mechanical Ventilation of the Asthmatic Patient in Respiratory Failure. Proc Am Thorac Soc. 2009;6(4):371-379. doi:10.1513/pats.P09ST4
  6. Laher AE, Buchanan SK. Mechanically Ventilating the Severe Asthmatic. J Intensive Care Med. 2018;33(9):491-501. doi:10.1177/0885066617740079
  7. Leatherman J. Mechanical ventilation for severe asthma. Chest. 2015;147(6):1671-1680. doi:10.1378/chest.14-1733