February 1, 2021

Background: It has well been established that low tidal volume ventilation minimizes potentially iatrogenic harms of mechanical ventilation.  What is less clear is the use of higher positive end expiratory pressure (PEEP) in patients without acute respiratory distress syndrome (ARDS). Use of PEEP helps prevent alveolar collapse and maintains recruitment of atelectatic and diseased alveoli.  This improves the distribution of lung aeration over a more homogenously inflated lung surface which in turn may improve oxygenation. Although PEEP reduces cyclical opening and closing of alveoli during ventilation, a higher PEEP could also lead to new lung injury (ventilator-induced lung injury), impair hemodynamics (reducing venous return) and could delay weaning/extubation.

December 15, 2020

Background: The COVID-19 Pfizer BNT162b2 vaccine, let’s just call it the COVID-19 Pfizer vaccine (so I don’t have to keep writing BNT162b2) is a novel mRNA vaccine developed to give immunity against the SARS CoV2 virus. It is synthesized mRNA packaged in small lipid nanoparticles but must be stored at extremely low temperatures (-70 C and 2 - 8 C for 5 days ) to prevent degradation.  The mRNA encodes for a small portion of the SARS CoV2 virus known as the spike protein and does not encode for the entire virus itself. This small lipid nanoparticle is injected into your body and then enters the cell. The lipid nanoparticles serve to protect and preserve the mRNA from degradation and allows it to enter cells readily.  After the mRNA enters the cells, the ribosomes will then take the mRNA and begin to synthesize this information to produce the spike protein portion of the SARS CoV-2 virus. The spike protein is what is believed to help the SARS CoV-2 virus enter human cell, replicate, and then lead to the syndrome known as COVID-19. This spike protein is believed to be the immunogenic portion of the virus that the body will then recognize as foreign and begin to develop an immune response against. The vaccine is given in 2 doses that are to be administered 3 weeks apart.

July 30, 2020

What is it HLH? Hemophagocytic Lymphohistiocytosis (HLH) is a rare and often fatal syndrome of uncontrolled and ineffective inflammatory response to a certain trigger. It is characterized by excessive proliferation of lymphocytes and macrophages (histiocytes), hence the name “lymphohistiocytosis”. This results in the overproduction of cytokines, responsible for many of the clinical features present in this syndrome. Familial, or genetic, HLH occurs as a result of a genetic mutation leading to impaired cytotoxic function. There have been several genetic mutations indicated in the development of HLH, including an association with congenital immunodeficiency syndromes, such as Chediak-Higashi, Griscelli and X-Linked Lymphoproliferative Syndromes. This form most often occurs within the first year of life (median age 8 months), with the majority of pediatric cases occurring <2 years of age, but can range from infancy to adulthood. Acquired HLH occurs in the setting of an underlying condition, such as immunodeficiency, malignancy, or autoimmune disease. When HLH is secondary to a predisposing autoimmune disease, it is referred to as macrophage activating syndrome (MAS).  Acquired HLH is the most common cause of this syndrome in adults, but this form can be seen in all ages. Overall, the syndrome is most often triggered by an infectious agent in an otherwise healthy person.

April 10, 2020

Airway Pressure Release Ventilation (APRV) is a mode of ventilation that allows spontaneous breathing throughout the ventilation cycle.  It is a time-cycled mode of ventilation between two levels of positive airway pressure with the main time on the high level and a shorter period of time during the expiratory release to facilitate ventilation. This may not be a mode of ventilation many ED physicians are comfortable and have experience with and in this podcast Frank Lodeserto, MD reviews how to setup, titrate, and wean patients on this mode of ventilation.
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