Pandemic 2009 influenza A in Argentina: a study of 337 patients on mechanical ventilation.
BACKGROUND
The rapid spread of the 2009 Influenza A (H1N1) around the world underscores the need for a better knowledge of epidemiology, clinical features, outcomes, and mortality predictors, especially in the most severe presentations.


OBJECTIVE
To describe these characteristics in patients with confirmed, probable, and suspected viral pneumonia caused by 2009 influenza A (H1N1) admitted to 35 intensive care units with acute respiratory failure requiring mechanical ventilation in Argentina, between June 3 and September 7.


METHODS
Inception-cohort study including 337 consecutive adult patients. Data were collected in a form posted on the Argentinian Society of Intensive Care website.


RESULTS
Proportions of confirmed, probable, or suspected cases were 39%, 8%, and 53% and had similar outcomes. APACHE II was 18 +/- 7; age 47 +/- 17 years; 56% were male; and 64% had underlying conditions, with obesity (24%), chronic obstructive respiratory disease (18%), and immunosupression (15%) being the most common. Seven percent were pregnant. On admission, patients had severe hypoxemia (Pa(O(2))/Fi(O(2)) 140 [87-200]), extensive lung radiologic infiltrates (2.87 +/- 1.03 quadrants) and bacterial coinfection, (25%; mostly with Streptococcus pneumoniae). Use of adjuvants such as recruitment maneuvers (40%) and prone positioning (13%), and shock (72%) and acute kidney injury requiring hemodialysis (17%), were frequent. Mortality was 46%, and was similar across all ages. APACHE II, lowest Pa(O(2))/Fi(O(2)), shock, hemodialysis, prone positioning, and S. pneumoniae coinfection independently predicted death.


CONCLUSIONS
Patients with 2009 influenza A (H1N1) requiring mechanical ventilation were mostly middle-aged adults, often with comorbidities, and frequently developed severe acute respiratory distress syndrome and multiorgan failure requiring advanced organ support. Case fatality rate was accordingly high.
Estenssoro
Elisa
E
Servicio de Terapia Intensiva, Hospital Interzonal de Agudos San Martín de La Plata, La Plata, Buenos Aires, Argentina. elisaestenssoro@speedy.com
Ríos
Fernando G
FG
Apezteguía
Carlos
C
Reina
Rosa
R
Neira
Jorge
J
Ceraso
Daniel H
DH
Orlandi
Cristina
C
Valentini
Ricardo
R
Tiribelli
Norberto
N
Brizuela
Matías
M
Balasini
Carina
C
Mare
Sebastián
S
Domeniconi
Gustavo
G
Ilutovich
Santiago
S
Gómez
Alejandro
A
Giuliani
Javiera
J
Barrios
Cecilia
C
Valdez
Pascual
P
D018806:APACHE; D000328:Adult; D001118:Argentina / Q000453:epidemiology; D015331:Cohort Studies; D004196:Disease Outbreaks; D005260:Female; D006801:Humans; D000860:Hypoxia / Q000401:mortality; D053118:Influenza A Virus, H1N1 Subtype; D007251:Influenza, Human / Q000150:complications / Q000401:mortality* / Q000628:therapy; D008297:Male; D008875:Middle Aged; D011018:Pneumonia, Pneumococcal / Q000150:complications / Q000401:mortality; D011247:Pregnancy; D012121:Respiration, Artificial; D012128:Respiratory Distress Syndrome / Q000209:etiology / Q000401:mortality / Q000628:therapy*