Keywords traumatic brain injury - intracranial pressure - prognosis
Palavras-chave traumatismo cranioencefálico - pressão intracraniana - prognóstico
Introduction
Traumatic brain injury (TBI) constitutes a relevant socioeconomic problem throughout
the world and is considered a major cause of death and incapacity, especially in individuals < 45
years old.[1 ]
[2 ] In Brazil, the mortality rates are influenced by several factors, and may reach
37% in some regions of the country.[3 ]
Intracranial pressure (ICP) reflects the connection between the internal contents
of the cranial cavity—which is composed primarily of cerebrospinal fluid (CSF), the
brain, and blood—and the volume of the skull. When the structures that make up the
skull are submitted to the same force, they respond differently, since they have different
densities, which can lead to an increase of the ICP.[4 ]
[5 ]
[6 ]
According to the guidelines of the Brain Trauma Foundation (BTF), ICP monitoring should
be considered as part of the standard care in patients suffering from severe TBI.
In Brazil, however, the Recommendations Report of the National Commission for the
Integration of Information Technology, published in 2014 by the Brazilian Unified
Health System (SUS, in the Portuguese acronym) under the title CONITEC 125, does not
recommend this practice because of the lack of clinical effectiveness of the procedure.
– This is contrary to the international and national guidelines, as well as to the
recommendations of the medical societies of the specialty.[7 ]
[8 ]
[9 ]
[10 ]
[11 ]
Therefore, the present study aimed to verify the prognosis of patients with severe
TBI who underwent ICP monitoring when compared with those who did not undergo the
procedure.
Materials and Methods
An observational, retrospective and quantitative study was performed.
Ethical Aspects
The present study only started after being approved by the Human Research Ethics Committee
(CEP, in the Portuguese acronym) of the Universidade do Extremo Sul Catarinense (UNESC),
under the number 2.271.904, and by the CEP of the Hospital São José, under the number
2.604.092.
Samples and Observational Groups
The sample was collected in a hospital in Criciúma, in the state of Santa Catarina,
Brazil. Patients who had been diagnosed with severe TBI (n = 129) and patients who used intraventricular catheters to monitor ICP due to severe
TBI (n = 134) between January 2009 and August 2017 were selected. Patients who either had
been diagnosed with pathologies different from severe TBI, were < 18 years old, or
who needed immediate neurosurgery at admission were excluded from the study.
Procedures
A data collection instrument was developed aiming to evaluate the main variables of
interest of the research, which allowed the comparison with other studies previously
performed on the same topic. The instrument evaluated four main domains: the epidemiological
profile of the population, the initial clinical evaluation, the radiological evaluation,
and the outcome of the case.
At the initial clinical evaluation, patients with TBI, with Glasgow Coma Scale scores
between 3 and 4 and presenting with mydriatic pupils were considered as subjects with
a reserved prognosis.
Statistical Analysis
Data analysis was performed with SPSS Statistics for Windows, version 22.0 (IBM Corp.,
Armonk, NY, USA). The qualitative variables were expressed by frequency and percentage,
and the quantitative variables by average and standard deviation (SD), when they presented
normal and average distribution, and by interquartile range when they did not follow
this type of distribution. The normality tests used were the Shapiro-Wilk and the
Kolmogorov-Smirnov tests.
The statistical analysis was performed by applying the Mann-Whitney U test, the Pearson
chi-squared test, and the Fisher Exact test, with a relevance level of p = 0.05; the analysis of residues was performed when a statistical significance was
observed. The magnitude of the association found was investigated by odds ratio (OR).
Results
The group that received ICP monitoring corresponds to 47.56% (n = 117) of the sample, with an average of 1.7 days of use of the catheter. Both in
those who were and the ones who were not submitted to ICP monitoring, males were the
most affected, with a prevalence of > 80% of the individuals evaluated (p = 0.392).
The age ranged between 18 and 88 years old, and 72.76% of the patients were < 50 years
old. The group receiving ICP monitoring was younger, with an average age of 36.38
years old and a SD of 17.05 years. The average age of the other group was 39.78 ± 18.14
years old (p = 0.135).
The main cause of TBI in the present study was an automobile accident, which was also
the main etiology in those who underwent ICP monitoring. In those who did not use
the catheter, other trauma mechanisms, such as aggression, gunshot wounds, and being
run over by a car, were more common (p = 0.001). ([Fig. 1 ])
Fig. 1 Mechanism of trauma. *Value obtained after Pearson chi-square test. Others: trampling,
assault and gunshot wounds.
In the initial clinical examination of the patients with severe TBI, the mydriatic
pupillary pattern was related to death, and normal pupil reaction pupils were related
to hospital discharge (p < 0.001). The use of the catheter was related both to the normal pupil reaction-pupils
and to the miotic pupils (p = 0.003).
Regarding the performance of cranial computed tomography (CT) scans, the monitored
group was submitted to a larger number of exams, with an average of 2.6 examinations
(p < 0.001), and the most common finding being cerebral edema. In relation to the patients
who were monitored, the finding of subdural hematoma (p = 0.014) and of midline deviation (p = 0.026) was statistically significant when compared with the other group.
Regarding the length of hospital stay, the group of patients who underwent ICP monitoring
were hospitalized for a longer time (p < 0.001) and remained longer in the intensive care unit (ICU) than the other group
(p = 0.005). ([Table 1 ])
Table 1
Length of hospital stay and in intensive care unit
Variables
Use of catheter, n (%)
p- value
Yes
No
n = 117
n = 129
Days of hospitalization [† ]
0–10
14 (12.0)
70 (54.3)[b ]
< 0.001**
11–20
35 (29.9)
28 (21.7)
21–30
54 (46.2)[b ]
20 (15.5)
> 30
14 (12.0)
11 (8.5)
Days of hospitalization [†† ]
10.00 (6–15.5)
4.00 (1–13)
0.005*
* Value obtained after application of Mann-Whitney U test.
** Value obtained after Pearson chi-squared test.
† Days of total hospital stay.
†† Days of hospitalization in the intensive care unit (values expressed in median and
interquartile range).
b Statistically significant value after the residue analysis.
When analyzing the prognosis of the patients, there is statistically significant evidence
that the individuals who used the catheter for ICP monitoring have a 47% chance of
dying, as opposed to the group that did not receive this monitoring (OR = 0.53; 95%
confidence interval [CI] 0.31–0.90; p = 0.009).
Regarding the complications, a statistically significant correlation between a hospital
stay > 30 days and the development of meningitis (p < 0.001) was shown, with the majority of these patients being submitted to ICP monitoring,
although the expected outcome for these patients (p = 0.018) had no correlation with the number of days of catheter use (p = 0.210). In addition, no statistically significant correlation was found between
the duration of catheter use, and other complications, such as infection at the place
of the surgical wound, and/or ventriculitis.
The monitored group was more likely to have motor deficit at hospital discharge (p = 0.036) and to need to progress to decompression 24 hours after being admitted to
the hospital. In contrast, unmonitored patients had a higher predicted rate of guarded
prognosis in the initial evaluation. ([Table 2 ])
Table 2
Characteristics of patients who were managed with and without intracranial pressure
monitoring
Variables
Use of catheter, n (%)
p- value
Yes
No
n = 117
n = 129
Reserved prognosis
Yes
2 (1.7)
48 (37.2)
< 0.001*
No
114 (98.3)[b ]
81 (62.8)
Need for decompression
Yes
54 (52.9)[b ]
26 (20.2)
< 0.001*
No
48 (47.1)
103 (5.2)
Motor deficit at hospital discharge
No
103 (45.6)
123 (54.4)
0.036*
Yes
14 (70.0)[b ]
6 (30.0)
*Value obtained after Pearson chi-squared test.
b Statistically significant value after the residue analysis.
Discussion
The main outcome of the present study was that the use of the catheter for ICP monitoring
is related to reduction in the mortality rate (OR = 0.53; 95% CI: 0.31–0.90) of patients
with severe TBI. Intracranial pressure monitoring is indicated in all patients with
severe TBI, that is, those who present a score between 3 and 8 points in the Glasgow
Coma Scale and have an abnormal cranial CT scan. In some cases, even with an unchanged
CT, monitoring is indicated if 2 or more of the following characteristics are observed
at the time of admission: pathological posture, age > 40 years old, or systolic blood
pressure < 90 mmHg.[8 ]
[12 ]
Increased ICP is the leading cause of death and sequelae following severe brain injury,
predominantly within the first 48 hours after the injury.[13 ] Intracranial pressure monitoring helps to recognize these elevations in PIC, allowing
for early interventions that can control secondary damage due to increasing pressure
within the rigid skullcap.[2 ]
[14 ] In the evaluated sample, more than 50% of the patients who used the catheter for
ICP monitoring evolved for decompression, confirming the efficacy of the method in
interpreting pressure variations early, thus allowing for a more appropriate clinical-surgical
approach.[15 ]
[16 ]
The present study reinforces data from other authors that have demonstrated a positive
association between ICP monitoring and mortality reduction in these patients.[2 ]
[12 ]
[17 ]
[18 ] However, some authors question its efficacy, demonstrating negative results with
ICP monitoring.[19 ]
[20 ]
[21 ]
[22 ] These studies have some limitations, such as the non-recognition of the cause of
death and the non-measurement of the CT findings of the patients.
In the present study, more than 80% of the patients in both groups were male. Similar
data have already been reported previously, even showing proportions > 3.5 men affected
for each woman.[23 ]
[24 ] This finding can be attributed to the greater exposure of males to TBI risk factors,
such as auto accidents and urban violence.[25 ]
Regarding the age group, a higher prevalence of severe TBI was observed in young adults,
and the population < 50 years old corresponded to > 70% of the sample. This is a period
of life with greater exposure to traumatic injuries, which is in line with the data
that defines automobile accidents as being the main etiology of TBI in the present
study, as reported by other authors.[24 ]
[26 ]
[27 ]
In the initial clinical examination, there was a correlation between the finding of
mydriasis and the clinical outcome of death. This finding in trauma patients suggests
a mechanical compression of the third cranial nerve or a decrease in the blood flow
to the brainstem.[28 ]
[29 ] Other authors have already demonstrated this association as the worst indicator
of the outcome of the patient, although the definition of the prognosis depends on
other factors, such as hospital interventions and resuscitation measures.[29 ]
[30 ]
[31 ] In the present study, no difference was observed in the frequency of pupillary alterations
between groups, unlike other authors who correlate abnormal pupillary reactions and
greater amount of catheter insertion for ICP monitoring.[32 ]
Patients who undergo ICP monitoring tend to have a longer hospital and intensive care
unit stay than those who are not submitted to the procedure.[6 ]
[19 ] In the present study, the data were reconfirmed before and after the exclusion of
the patients who died, possibly due to the longer survival of these patients when
compared with the non-monitored group.[12 ]
[33 ]
There was an association between the use of the catheter and the development of meningitis,
a complication already described by other authors, who correlate it with a monitoring
time > 5 days.[34 ] In the present study, there was no statistical significance regarding this temporal
correlation, since the patients who developed meningitis had an average time of use
of the catheter of 3.53 (SD: 1.92) days. The insertion of the catheter itself is considered
as an independent risk factor for the development of meningitis.[8 ]
[35 ] Moreover, other factors found in the present study contribute to this finding, such
as prolonged hospital and ICU stay, as well as the TBI itself.[35 ]
The patients who received ICP monitoring underwent a larger number of CT scans, probably
due to the increased hospital stay and to the necessity of severe TBI control. Cerebral
edema was the most common finding, present in 59% of the CT scans performed. The literature
reports that cerebral edema appears between 24 and 48 hours after the trauma, due
to fluid accumulation, and it can be considered as a predictive factor of increased
ICP.[36 ]
When comparing the two groups, we observed a higher frequency of subdural hematoma
in those who received ICP monitoring. However, we did not find a relation between
this finding and a worse prognosis, as has been described in other studies.[27 ]
[37 ] Although there is no specific correlation between CT findings and ICP value, this
is the examination of choice for patients with severe TBI because it allows the etiological
diagnosis and indicates findings suggestive of intracranial hypertension.
The present study has some limitations, such as the impossibility of performing a
periodic follow-up of the patients after they were discharged. Although the association
between catheter use and a greater amount of motor deficit at the time of the discharge
was verified, it was not possible to describe the long-term clinical outcome.
Furthermore, the guidelines regarding the use of the catheter for ICP monitoring do
not constitute a universal protocol, and the final decision involves multiple factors,
among them the clinical condition of the patient and the judgment of the neurosurgeon.
Therefore, it is possible to presume a reserved prognosis, in which the real perspective
of recovery can be considered null and the use of certain procedures presents a smaller
benefit than its possible complications.
We suggest new studies that contemplate protocols for a more uniform selection of
patients, excluding the selection bias, which may differ greatly when indicated by
different professionals, modifying the final results.
Conclusion
In the present study, it was evidenced that the use of the catheter for ICP monitoring
was associated with lower hospital mortality, suggesting that this is a predictor
of improvement in the prognosis of the patients submitted to ICP monitoring. This
is due to the sensitivity of the method regarding an early diagnosis of increases
in the ICP, which enables a prompter intervention and reduces possible sequelae due
to hypoxia or ischemia secondary to intracranial hypertension.
