Critical care services and 2009 H1N1 influenza in Australia and New Zealand.
BACKGROUND
Planning for the treatment of infection with the 2009 pandemic influenza A (H1N1) virus through health care systems in developed countries during winter in the Northern Hemisphere is hampered by a lack of information from similar health care systems.


METHODS
We conducted an inception-cohort study in all Australian and New Zealand intensive care units (ICUs) during the winter of 2009 in the Southern Hemisphere. We calculated, per million inhabitants, the numbers of ICU admissions, bed-days, and days of mechanical ventilation due to infection with the 2009 H1N1 virus. We collected data on demographic and clinical characteristics of the patients and on treatments and outcomes.


RESULTS
From June 1 through August 31, 2009, a total of 722 patients with confirmed infection with the 2009 H1N1 virus (28.7 cases per million inhabitants; 95% confidence interval [CI], 26.5 to 30.8) were admitted to an ICU in Australia or New Zealand. Of the 722 patients, 669 (92.7%) were under 65 years of age and 66 (9.1%) were pregnant women; of the 601 adults for whom data were available, 172 (28.6%) had a body-mass index (the weight in kilograms divided by the square of the height in meters) greater than 35. Patients infected with the 2009 H1N1 virus were in the ICU for a total of 8815 bed-days (350 per million inhabitants). The median duration of treatment in the ICU was 7.0 days (interquartile range, 2.7 to 13.4); 456 of 706 patients (64.6%) with available data underwent mechanical ventilation for a median of 8 days (interquartile range, 4 to 16). The maximum daily occupancy of the ICU was 7.4 beds (95% CI, 6.3 to 8.5) per million inhabitants. As of September 7, 2009, a total of 103 of the 722 patients (14.3%; 95% CI, 11.7 to 16.9) had died, and 114 (15.8%) remained in the hospital.


CONCLUSIONS
The 2009 H1N1 virus had a substantial effect on ICUs during the winter in Australia and New Zealand. Our data can assist planning for the treatment of patients during the winter in the Northern Hemisphere.
Webb
Steven A R
SA
Pettilä
Ville
V
Seppelt
Ian
I
Bellomo
Rinaldo
R
Bailey
Michael
M
Cooper
David J
DJ
Cretikos
Michelle
M
Davies
Andrew R
AR
Finfer
Simon
S
Harrigan
Peter W J
PW
Hart
Graeme K
GK
Howe
Belinda
B
Iredell
Jonathan R
JR
McArthur
Colin
C
Mitchell
Imogen
I
Morrison
Siouxzy
S
Nichol
Alistair D
AD
Paterson
David L
DL
Peake
Sandra
S
Richards
Brent
B
Stephens
Dianne
D
Turner
Andrew
A
Yung
Michael
M
D000293:Adolescent; D000328:Adult; D000368:Aged; D001315:Australia / Q000453:epidemiology; D001509:Bed Occupancy / Q000706:statistics & numerical data; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D005260:Female; D006801:Humans; D015994:Incidence; D007223:Infant; D053118:Influenza A Virus, H1N1 Subtype; D007251:Influenza, Human / Q000453:epidemiology* / Q000628:therapy; D007362:Intensive Care Units / Q000706:statistics & numerical data*; D007902:Length of Stay; D008297:Male; D008875:Middle Aged; D009520:New Zealand / Q000453:epidemiology; D010343:Patient Admission / Q000706:statistics & numerical data; D011247:Pregnancy; D055815:Young Adult