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Mechanical Ventilation in ARDS - USMLE

FiO2 and PEEP both use to improve oxygenation, in ARDS, in the beginning you give high FiO2 and PEEP to improve oxygenation, once PaO2 is normal

then you first decrease FiO2 and keep it below 60 and then decrease PEEP, to wean off your target FiO2 should be less then 40

Note :

  • Increasing FiO2 depresses respiratory drive
  • PEEP keeps alveoli open at the end of expiration and it improves ventilation and gas exchange
  • FiO2 should not be more than 60 for more than 48hrs it will cause oxygen toxicity, which will further destroy the lung.

Immunodeficiency Disorders - ( Easy way to Remember ) - USMLE


B cells normal in numbers ; but decrease in IgG IgM and IgA

  • Recurrent sinopulmonary infections in adults 
  • Decreased response to Antigen stimulation of B cells .
  • NORMAL amount of lymphoid tissues 

Rx : IV immunoglobulins

X-linked (Bruton) Agammaglobulinemia :

  • Male Children 
  • B cells and Lymphoid tissue are diminished 
  • Absence of the tonsils, adenoids , lymph nodes . T cell NORMAL 



Combined so Both B and T cells - related to both : B cells : recurrent sinopulmonary infection as early 6 month. T cells : Candida , AIDS , PCP

Rx : BMT

IgA deficiency :

  • sinopulmonary infections : Difference it also have Atopic diseases , Anaphylaxis to blood tranfusion when blood is given from a patient who has normal levels of IgA
  • Sprue like condition with fat malabsorption 

Rx : infections and use blood from igA-deficient donors or that has been washed.

Hyper IgE: skin infections with staph.

lymph nodes with purulent material leaking out . Abnormal NBT testing .

Hepatitis C associated problems

Bacillary angiomatosis vs Kaposi sarcoma

Bacillary angiomatosis also known as Cat scratch disease

by : Bartonella spp.

Transmission : Cat scratch

Lesions : Red color

bacillary angiomatosis-its a superificial vascular proliferation,biopsy shows neutrophilic inflammation

Kaposi sarcoma : HHV-8

lesions violaceous color

Kaposi's sarcoma(HHV-8)- its the neoplastic proliferation of vasculature, biopsy shows lymphocytic inflammation.

Being a Doctor what do you know about Zika Virus ?

Zika Virus is trasmitted by mosquitos of the Aedes genus

Affected countries : Brazil , Bolivia , paraguay , Ecuador , Colombia , Mexico
Haiti , Dominican Republic , Panama , Costa Rica , El salvador

Clinical features :

Vague last for upto a week

Dx : Serology

Symptoms :
  • Fever , Rash , Joint pain , Conjunctivitis , Myalgia , Headaches , Pain behind the eyes and Vomiting
  • Only 1 in 4 develop symptoms 
  • Mostly seen in pregnant women --- lead to infant microcephaly

Prevention :
  • Insect repellent , wear long sleeved , long pants - covered extremities 
  • Rest 
  • Hydration 
  • Antipyretic and analgesics : Tylenol  (acetaminophen)