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| Journal of the New Zealand Medical Association,
11-September-2009, Vol 122 No 1302
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Time to definitive care for patients with moderate
and severe traumatic brain injury—does a trauma system matter?
Ritwik Kejriwal, Ian Civil
The presence of a trauma system has been associated with
decreased mortality and improved outcomes by potentially speeding up transfer of
trauma patients to a major trauma
centre.1–3 This is particularly relevant
in patients with head injuries where time to neurosurgical intervention from the
time of significant traumatic brain injury (TBI) is important in determining the
outcome.4 North American guidelines recommend a
maximum of four hours from the time of injury to neurosurgical attention for
patients requiring evacuation of an intracranial
haematoma.4–7
Trauma care in New Zealand is delivered in an ad hoc trauma
system as opposed to a regional trauma system.8
Auckland City Hospital (ACH) provides adult brain trauma care for a population
of approximately two million people in the upper North Island of New Zealand
with the most distant referring hospital 346 km from ACH by
air.9 Patients with TBI are transported to the
closest regional hospital for airway, breathing and circulation assessment and
stabilisation. Once haemodynamically stable, an urgent computed tomography brain
scan is performed that is then reviewed electronically by the neurosurgeon and
intensivist in ACH. Transfer is recommended on the basis of a need for
neurosurgical intervention or brain-oriented intensive care.
The objectives of this study were to determine the timelines
associated with the sequence of care for TBI patients and identify any
correlations between time to definitive care and outcome. We aimed to do so by
comparing patients that were transported directly to ACH with those transferred
from another hospital, as well as comparing the data with the current
literature.
Patients and MethodsThe study was carried out at ACH, New Zealand. The ACH
Trauma Registry was interrogated for all patients admitted in 2004 with an
Abbreviated Injury Scale (AIS) of 3 or greater for head injury. The registry
used AIS-90 (98 update) version software.10
This extraction method was selected as Glasgow Coma Scale (GCS) on arrival is
often confounded by intoxication or other injuries. Therefore we sought to
specifically identify that cohort of TBI patients who had a clinically
significant TBI.
The ACH Trauma Registry includes all patients
presenting to the hospital following injury who are admitted. 1137 patients were
recorded in the ACH registry in 2004 calendar year. Patients who presented with
an injury due to an underlying chronic subdural haematoma were not included in
the Registry.
The following data were extracted from the registry:
patient demographics, AIS, Injury Severity Score (ISS), details of injury,
entrapment time, GCS, presence of other trauma, mode of transport, time and type
of surgery, intracranial pathology, in-hospital survival, length of Intensive
Care Unit (ICU) stay, and length of stay in the hospital. Patients transferred
to ACH after 24 hours and patients without time of injury or time of arrival
were excluded.
The primary outcomes of the study were median time from
injury to arrival at ACH, time to neurosurgical intervention, mortality, length
of intensive care, and length of hospital stay. The secondary outcome was effect
of age, sex, mode of transport, ISS, GCS, presence of multiple trauma and road
crashes on time from injury to arrival at ACH.
Statistical analysis—All
analysis was performed using SAS version 8.2 (SAS Institute Inc., Cary, NC,
USA). Comparison between primary and secondary groups was made using chi-square
tests for equal proportion and student t-tests, and validated using Wilcoxon
rank sum tests. Time from injury to arrival was found to be well approximated by
a lognormal distribution and was consequently log-transformed prior to analysis.
The univariate relationships between log (time from injury to arrival) and all
other variables were assessed using linear regression, whilst multivariate
analysis was performed using multiple linear regressions.
Multivariate models were constructed using a stepwise
selection procedure and validated using a backwards elimination procedure.
Results are presented as parameter estimates with a standard error. A two-sided
p-value of 0.05 was considered to be statistically significant.
Results198 patients were admitted at ACH in 2004 with moderate and
severe TBI (defined as an AIS score of 3 or greater for head injury) in this
study. Baseline data is outlined in Table 1; 48% of patients were transferred
from another hospital.
Table 1. Baseline data
Fifteen percent of the patients were excluded due to time of
injury or arrival time not being available, or due to patients presenting to the
trauma hospital more than 24 hours after injury. After excluding these patients,
the data was divided in two groups—patients transported to ACH directly
from the scene of injury (PRIMARY group) and patients taken to another hospital
before they were transferred to ACH (SECONDARY group). There were 97 patients
(57%) in the PRIMARY group and 73 (43%) patients in the SECONDARY group. 43
(59%) patients in the SECONDARY group were transferred from two hospitals within
Auckland region. Baseline comparison between the two groups at ACH is outlined
in Table 2.
Neurosurgical procedures performed within 24 hours of injury
were included in the analysis. 24 neurosurgical procedures were performed on 13
patients in the PRIMARY group and 18 procedures were performed on 16 patients in
the SECONDARY group. 20 procedures were excluded due to missing data or surgery
performed later than 24 hours after injury.
Primary outcome of median time from injury to arrival at ACH
was adjusted for entrapment (Table 3). Overall the median time from injury to
arrival was 1 hour 43 minutes. The median time from injury to arrival at ACH as
well as to neurosurgery for the SECONDARY group was significantly greater than
the PRIMARY group (p<0.0001). There were no statistically significant
differences between the two groups for in-hospital survival, length of ICU stay,
and length of hospital stay.
Table 2. PRIMARY group vs SECONDARY
Group
Table 3. Primary outcome
Time to definitive care was analysed for patients
transferred to ACH from other hospitals in Auckland region as well (Table 4).
Median time from injury to arrival for Auckland region transfers (6 hours 16
minutes) was significantly greater than the PRIMARY group (p<0.0001).
Table 4. Analysis of Auckland region
transfers
Transport by road ambulance (p=0.04) and road crashes
(p=0.05) were predictors of a reduction in time from injury to arrival in
univariate regression analysis as well as the multivariate model.
DiscussionIt is well established that time to neurosurgery from time
of injury is critical in determining neurological outcome. In the United States,
the Brain Trauma Foundation recommends a time limit of four hours to surgical
intervention for acute subdural haematomas based on 1981 study by Seelig et
al.4
European guidelines do not set a time frame, but there is a
consensus that the speed of referral and transfer to neurosurgical care may
critically influence the outcome.3,11 Even as
Wilberger et al found no improvement in mortality rate in patients treated
within four hours,12 other studies show that
time from point of neurological deterioration to surgery is related to improved
outcome.13,14
From the time of injury, the PRIMARY group median time to
arrival (50 minutes) and median time to surgery (3 hours 50 minutes) at ACH were
within four hours. On the other hand, median time from injury to arrival at ACH
for the SECONDARY group was well outside the recommended guidelines (7 hours 3
minutes). Therefore patients transported directly to ACH are likely to undergo
neurosurgery within international guidelines whereas those transferred are not.
These times are comparable to the ones reported in the
literature. Our SECONDARY group times were similar to a Liverpool Hospital study
that reported a median time to definitive care of 6 hours 39 minutes for
patients transferred from another hospital.15
Another study reported a median delay of 4 hours and 22 minutes in patients who
were transferred from another hospital.16
ACH had significantly larger proportion of patients
transported from another hospital (48%) compared to the trauma systems in the
literature16, which means that the effect of
undue delay and its potential effect on outcome even more important than in
systems where there are fewer transfers. It is particularly relevant that even
from hospitals within the metropolitan region there was a significant delay to
from injury to surgery compared with those transported directly to ACH.
While there were no differences between the two groups in
hospital stay ICU stay, and mortality in this study, the numbers were very
small. A similar study in western Virginia found that patients transferred from
another hospital had worse outcomes in the above-mentioned parameters compared
to patients directly transferred to a major trauma
centre.17
The linear regression analyses of ACH data suggests that
transport by road is associated with shorter transport times than when transport
is by helicopter. This is due to rotary wing transfers being used sparingly in
the region serviced by ACH and being limited to patient transfers from places
with difficult road access.
Benefits of a state trauma system have been well documented.
Cooper et al assessed management of road traffic fatalities and suggested that
having a trauma system in Victoria, Australia is likely to decrease preventable
death rates.18 Similarly, Mullins et al
attributed improved outcomes among patients with head injuries in Oregon to the
institution of a state trauma system.2 It
compared the state trauma system of Oregon to an ad-hoc trauma system of
Washington and found a significant difference in patient mortality. Another
study carried out in Rhode Island concluded that the presence of a major trauma
centre that is not part of a state trauma system results in delays in time to
definitive care for injured patients.1
State trauma systems have triage criteria that allow
patients with major trauma injury to be directly transported to a designated
major trauma centre. This is related to improved outcomes according to Poon et
al,19 who concluded that direct admission of
head injury patients to the primary care of the neurosurgeons is the best policy
in the reduction of mortality and morbidity. Patel et al and Cooper et al
provided strong evidence as well in his observational study that patients who
have neurosurgical trauma are better managed in a neurosurgical centre as part
of a Level 1 Trauma Centre.14,20
While the ACH SECONDARY group were not worse off in outcomes
measured, based on the literature ACH trauma care may be improved by an
introduction of a triage criteria or an ambulance bypass protocol. Lind et al
stated that triaging is not an option for patients outside
Auckland,9 but triaging for patients within
Auckland may be beneficial as 43 out of 73 patients in the secondary group were
transferred from hospitals within the Auckland metropolitan area. This will
potentially enable these patients to undergo neurosurgical intervention within
recommended guidelines.
This retrospective study is only a snapshot of the
performance of ACH ad-hoc trauma system in one calendar year. A limitation of
the study is incomplete data for some of the patients at ACH. Nonetheless,
approximately 85% of the patients with AIS of three or greater were still
included for primary outcome analysis making it a fair representation of the
baseline population.
Another limitation was the small proportion of patients that
underwent neurosurgery within 24 hours, which made it difficult to compare time
to surgery between the two groups. This study was also limited by lack of
available data from the hospitals of primary presentation. Were NZ to have a
national trauma registry, such as the state registry in Victoria, Australia, a
much more comprehensive dataset could have been assembled to allow more
comprehensive analysis of this topic.
ConclusionAlmost half of the TBI patients treated at ACH in 2004 were
transferred from another hospital and they arrived well outside the recommended
time guidelines. While this made no difference in patient outcomes as measured
by LOS and survival in our study, there may be benefit in having a greater
proportion of patients directly transferred from the scene of injury.
Development of a prospective national trauma registry would allow ongoing
analysis of the process of trauma care and outcome in NZ. Future prospective
studies are recommended to look at outcomes including neurological outcome of
patients with TBI in New Zealand.
Competing interests: None known.
Author information: Ritwik Kejriwal, House
Officer; Ian Civil, Director; Trauma Services, Auckland
City Hospital, Auckland
Correspondence: Dr Ritwik Kejriwal, 6U
Carlton Gore Road, Grafton, Auckland, New Zealand. Email: ritwikkejriwal@gmail.com
References:
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