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740 S P E C I A LT Y P R A C T I C E I N C R I T I C A L C A R E

Research vignette, Continued
Conclusions increased risk factors within the pregnancy cohort and a potential
Pregnancy is a risk factor for critical illness related to 2009 H1N1 delay in the commencement of anti-viral treatment for severe
influenza, which causes maternal and neonatal morbidity and influenza during pregnancy. Notably, the poor maternal and neo-
mortality. natal outcomes are reflected upon. These themes are discussed
with appropriate reference to other literature, i.e. ‘what is known
Critique about the topic,’ and how this study has added to ‘what is known’.
A prospective, collaborative study was rapidly established follow- The clinical implications are also highlighted, particularly regard-
ing the onset of the H1N1 influenza pandemic in 2009. Every ICU ing the potential prevention of severe H1N1 influenza in preg-
in Australia and New Zealand (n = 187) was involved with every nancy now that a vaccine is available and recommended for all
confirmed H1N1 influenza ICU admission prospectively entered in pregnant women.
to the INFINITE database. Over 700 affected patients were admitted
to Australian and New Zealand ICUs during the three months of This is the largest study to date and is also the most comprehensive
winter (June–Aug 2009). Of these, 64 (9%) were noted to be preg- study published about influenza in pregnancy, obstetric outcomes
nant or postpartum; thus pregnant and postpartum admissions and neonatal outcomes. Although the overall numbers were still
were an over-represented cohort. 166 relative small (n = 64), it was a population-based study with con-
sistent findings across multiple clinical sites. Unfortunately, the
This pregnant and postpartum cohort was the subject of the disconnection of ICU and maternity services makes complete
follow-up study, conducted collaboratively by the ANZIC-RC and follow-up very difficult. For example, it is very challenging to
the Australasian Maternity Outcomes Surveillance System (AMOSS), follow-up a pregnant woman admitted to ICU at 21 weeks’ gesta-
in which an additional data set were retrospectively collected on tion, in a hospital where she was not booked in to receive her
all women, including data on obstetric and neonatal outcome. maternity care, when she is discharged pregnant and gives birth
The paper clearly sets the context for the study, outlining the 18 weeks later in an unrelated hospital. Even if the researcher is
increased risk of severe influenza associated with pregnancy and a aware of the intended hospital for birth, the woman may give birth
lack of data on the obstetric and neonatal outcomes. The methods in another location unexpectedly. The study clearly demonstrates
chosen to conduct this study were appropriate and in part were serious maternal and morbidity for both the mother and her baby.
selected because of the opportunity presented with the primary The results build a strong case for all pregnant women to be
INFINITE study. The method for identifying cases was described offered influenza vaccine during pregnancy; further, that the
and the inclusion criteria are clear. Notably, 28 days was used to vaccine will offer most benefit to the woman if administered prior
define postpartum and not the commonly-used definition of 42 to 20 weeks’ gestation.
days; there is no explanation for this. The AMOSS research pro- One limitation not identified by the authors is the possibility that
cesses were not well described and it is unclear how the additional the ICU admission threshold may have differed for pregnant or
data were obtained. Nevertheless, the variables collected are postpartum women. No severity of illness/severity of lung injury
stated clearly. In order to calculate relative risks, the authors used score was reported. Examination of the INFINITE cohort would
available population birthing data; whilst these data were not suggest that there was no difference in ICU admission threshold.
precise for the timeframe the study was conducted, they were the The median length of ICU stay (days), proportion requiring
best available data and the processes in which the population mechanical ventilation (%), median length of ventilation (days),
birthing data were used are clearly explained.
need for ECMO (%), vasopressor use (%), RRT (%) were not differ-
All cases are accounted for and a flow chart is included to demon- ent between the general INFINITE cohort and the pregnant/
strate this. Relative risks are reported for women in the first half of postpartum sub-set.
their pregnancy, women in the second half of their pregnancy,
postpartum women and pregnant/postpartum women compared Finally, this study is a good example of, and highlights the benefit
with non-pregnant women of childbearing age. The highest risk of, collaborative research. The study was conducted by two teams
time for maternity patients was in the second half of pregnancy. of researchers; intensive care clinicians and maternity providers.
Other additional risk factors are clearly identified including the Together, with the assistance of every ICU in Australia and New
woman’s indigenous status and high body mass index (BMI). Tables Zealand, they were able to conduct a population-based study that
and figures have been used well to communicate large amounts identified all pregnant and postpartum women admitted to ICU
of data. Figures 1 and 2, in particular, are helpful and easy to with H1N1 influenza during the winter of 2009. This level of col-
interpret. laboration enabled the researchers to study the largest possible
number of cases of a rare event. The findings of the study reflect
The discussion explores themes identified from the research find- the benefits of such a collaboration, with clinically, meaningful
ings including the risk posed by pregnancy on influenza infection, data obtained.