Download “five finger” hypoxia + rsv in adults

SJS Jan-04
“FIVE FINGER” HYPOXIA + RSV IN ADULTS
Hall CB. Respiratory syncytial virus and parainfluenza virus. N Engl J Med. 2001;344:1917-1927
Take home points:
1. Use the “five finger” approach to hypoxemic respiratory failure to quickly understand the
pathophysiology behind your patient’s hypoxia.
2. RSV in adults is being recognized more frequently and can present with respiratory failure.
3. Currently there is no definitive treatment for RSV, so prevention is key.
Hypoxemic respiratory failure, a “five finger” approach:
• Low FiO2
• Anatomic shunt
• Hypoventilation
• Diffusion defect
• V/Q mismatch
RSV – Epidemiology and transmission:
• RSV causes a large burden of disease in young children, but is increasingly being recognized as an
important pathogen in adults (immunocompromised and immunocompetent)
• RSV is a seasonal virus, causing disease from November to May, with peak incidence in January and
February.
• Transmission requires direct contact with large droplets or secretions (e.g. cuddling an infant), or contact
with fomites (RSV can last for a long time on clothes, toys, hospital rooms, etc).
RSV – Pathophysiology:
• RSV causes inflammation primarily in the bronchioles of the lung. Therefore, it causes necrosis and
sloughing of the epithelium of the small airways with resultant edema, mucus formation, and finally
obstruction of air flow.
• It can cause a wide variety of clinical features, ranging from URI symptoms, to cough and pneumonia
RSV – Clinical features:
• In adults, RSV often goes undiagnosed and unsuspected. In most labs, it can now be diagnosed by a
panel of tests for respiratory viruses (DFA, ELISA); sensitivity and specificity > 90%.
• Because RSV causes obstruction of small airways, classic clinical findings include hyperinflation,
atelectasis, and wheezing.
• However, RSV can cause a wide variety of clinical features, ranging from URI symptoms, to cough and
pneumonia symptoms, to severe respiratory failure, ARDS, and death.
• Histologic resolution begins within days of onset of symptoms, but the new epithelial cells lack cilia
which makes clearing debris for the airways difficult.
• Clinical resolution typically takes 4-8 weeks.
RSV – Treatment and prevention:
• Ribavirin has been used in children, and has improved oxygenation and symptom scores in some studies.
However, these studies haven’t shown a mortality benefit. In adults, ribavirin has not been shown to be
effective.
• Bronchodilators can help, but steroids have no role unless the patient has concomitant asthma.
• No vaccine available because immunity wanes (even after natural infection) and dominant strains shift
yearly.
• Preventive measures: hand washing and avoiding little kids is key!
For more information and resources developed by UCSF medical housestaff,
please browse the following links:
UCSF Department of Medicine, Housestaff Website:
• Resources and information for our housestaff
• Location: http://medicine.ucsf.edu/housestaff/
UCSF Department of Medicine Hospitalist Handbook:
• Available free of charge for download to PDA
• Updated annually and written by UCSF medical residents
• Location: http://medicine.ucsf.edu/housestaff/handbook/
UCSF Chief Medical Residents’ Cover Sheets:
• Covering a wide array of topics that were discussed at morning report
• Location: http://medicine.ucsf.edu/housestaff/Chiefs_cover_sheets/