Intracranial pressure (ICP) monitoring is regarded as standard care for patients with severe traumatic brain injury (TBI). Nevertheless, even in high-income countries, the efficacy of ICP monitoring has been questioned. The identification of a group of intensivists in Bolivia and Ecuador who routinely manage TBI patients without ICP presented an opportunity for Randall Chestnut and colleagues to conduct a randomized trial comparing ICP monitoring to clinical examination and neuroimaging in patients with severe TBI. Their results were published in the December 27, 2012, issue of The New England Journal of Medicine.
This multicenter, parallel-group trial, randomized assignment of subjects to ICP monitoring (experimental) or imaging and clinical examination alone (control) in patients with severe TBI in four Bolivian and two Ecuadorian hospitals from 2008 to 2011. Patients in the experimental group were treated to maintain an ICP <20 mm Hg. The primary outcome was a composite of 21 components, including measures of survival, impairment of consciousness and functional status. Clinicians and study personnel were not blinded to the experimental intervention. The blocked Wilcoxon test, logistic proportional odds models and Cox models were used to test the primary hypothesis by adjusting for factors such as study site, age and severity of injury.
The experimental group included 157 patients while the control group included 167 patients. There were no significant differences in prognostic factors between the groups. Patients in the control group were statistically significantly more likely to receive hypertonic saline and hyperventilation; there were no other differences in co-interventions or other treatments such as neurosurgical procedures (i.e., craniectomy). No significant differences existed between the groups in terms of the primary outcome (proportional odds ratio [OR], 1.09; 95% confidence interval [CI], 0.74 to 1.58; P=0.49). Cumulative mortality at six months was 39% in the experimental group and 41% in the control group (P=0.60). Patients in the control group were more likely to have a higher median intensive care unit length of stay (4.8 days [interquartile range (IQR), 2.3-7.4] vs. 3.4 days [IQR, 1.1-7.0]; P=0.002). The authors concluded that care focused on maintaining ICP <20 mm Hg was not shown to be superior to care guided by clinical examination and repeat neuroimaging.
As ICP monitoring is presently endorsed as the standard of care for management of TBI, this study is bound to generate discussion within the neurocritical care community. Early criticisms include lack of external generalizability, since less than half of the enrolled patients (45%) were treated by prehospital emergency medical services. Patients might have had different degrees of severe TBI compared to patients in higher-income countries. Moreover, none of the subjects received rehabilitation or advanced medical care after discharge. ICP monitoring did not include placement of ventricular catheters, which may have additional therapeutic and diagnostic benefits in TBI patients. The therapeutic protocols in the experimental and control groups were similar, but the protocols alone may account for variable efficacy. The results from this study do not refute the tenet that aggressive treatment is important for patients with severe TBI, but the means for guiding targeted therapies deserves reassessment.
Concise Critical Appraisal is a regular feature authored by SCCM member Samuel M. Galvagno Jr., DO, PhD. Each installment highlights journal articles most relevant to the critical care practitioner.