How does the position of the backrest of the bed (and therefore the position of the head) affect people who have had an injury to the head that caused serious brain damage?
Raised pressure within the skull (intracranial hypertension) because of swelling is the most common cause of death and disability in brain‑injured people. How well someone with intracranial hypertension recovers often depends on how they are treated. Some people think that some positions of the backrest of the bed (called the 'head-of-bed elevation' or HBE) might affect this pressure and improve the person's recovery. The position of the backrest of the bed is a simple and cheap intervention. This is important as most brain injury happens in low- and middle-income countries with relatively undeveloped health systems and few resources to deal with brain injury.
In March 2017 the review authors searched for randomised studies.
We found three small studies, with a total of 20 people (11 adults and 9 children). The studies had a cross-over design (participants received the study interventions in a random order, and served as their own control) and looked at the effect of different head positions. Researchers measured the pressure inside the skull (intracranial pressure (ICP)) and the pressure gradient causing blood flow to the brain (cerebral perfusion pressure (CPP)). Two studies were funded by research grants from the national Department of Health, and one study received no funding.
At the time of follow-up 28 days following hospital admission, one child had died. None of the studies assessed quality of life, Glasgow Coma Scale (a measurement of how conscious someone is), or disability. The studies gave varied results and our certainty in the results is very low, so we do not consider the body of evidence to be reliable. None of the studies found any evidence of a change in CPP due to different backrest positions. The results for ICP were more mixed but there is still no convincing evidence that HBE changes ICP. There is insufficient evidence to say whether the intervention is safe. One child experienced an increase in ICP in response to the intervention, which resolved when the height of the bed was returned to the normal position. We are uncertain about the effects of different backrest positions in people with serious brain injury.
Quality of the evidence
The body of evidence for this research question is very low due to variability in physiological response in the study participants, unclear risk of bias in the study methods, and the small number of people enrolled in each study.
We are uncertain about the effects of different backrest positions in people with serious brain injury. Well-designed and larger trials are needed. Trials also need to measure the right patient outcomes over a longer period of time in order to understand how and when different backrest positions can affect people with brain injury.
The lack of consistency among studies, scarcity of data and the absence of evidence to show a correlation between physiological measurements such as ICP, CCP and clinical outcomes, mean that we are uncertain about the effects of HBE during intensive care management in people with severe TBI.
Well-designed and larger trials that measure long-term clinical outcomes are needed to understand how and when different backrest positions can affect the management of severe TBI.
Traumatic brain injury (TBI) is a major public health problem and a fundamental cause of morbidity and mortality worldwide. The burden of TBI disproportionately affects low- and middle-income countries. Intracranial hypertension is the most frequent cause of death and disability in brain-injured people. Special interventions in the intensive care unit are required to minimise factors contributing to secondary brain injury after trauma. Therapeutic positioning of the head (different degrees of head-of-bed elevation (HBE)) has been proposed as a low cost and simple way of preventing secondary brain injury in these people. The aim of this review is to evaluate the evidence related to the clinical effects of different backrest positions of the head on important clinical outcomes or, if unavailable, relevant surrogate outcomes.
To assess the clinical and physiological effects of HBE during intensive care management in people with severe TBI.
We searched the following electronic databases from their inception up to March 2017: Cochrane Injuries' Specialised Register, CENTRAL, MEDLINE, Embase, three other databases and two clinical trials registers. The Cochrane Injuries' Information Specialist ran the searches.
We selected all randomised controlled trials (RCTs) involving people with TBI who underwent different HBE or backrest positions. Studies may have had a parallel or cross-over design. We included adults and children over two years of age with severe TBI (Glasgow Coma Scale (GCS) less than 9). We excluded studies performed in children of less than two years of age because of their unfused skulls. We included any therapeutic HBE including supine (flat) or different degrees of head elevation with or without knee gatch or reverse Trendelenburg applied during the acute management of the TBI.
Two review authors independently checked all titles and abstracts, excluding references that clearly didn't meet all selection criteria, and extracted data from selected studies on to a data extraction form specifically designed for this review. There were no cases of multiple reporting. Each review author independently evaluated risk of bias through assessing sequence generation, allocation concealment, blinding, incomplete outcome data, selective outcome reporting, and other sources of bias.
We included three small studies with a cross-over design, involving a total of 20 participants (11 adults and 9 children), in this review. Our primary outcome was mortality, and there was one death by the time of follow-up 28 days after hospital admission. The trials did not measure the clinical secondary outcomes of quality of life, GCS, and disability. The included studies provided information only for the secondary outcomes intracranial pressure (ICP), cerebral perfusion pressure (CPP), and adverse effects.
We were unable to pool the results as the data were either presented in different formats or no numerical data were provided. We included narrative interpretations of the available data.
The overall risk of bias of the studies was unclear due to poor reporting of the methods. There was marked inconsistency across studies for the outcome of ICP and small sample sizes or wide confidence intervals for all outcomes. We therefore rated the quality of the evidence as very low for all outcomes and have not included the results of individual studies here. We do not have enough evidence to draw conclusions about the effect of HBE during intensive care management of people with TBI.