Zero Degree Head Positioning in Hyperacute Large Artery Ischemic Stroke (ZODIAC)

  • End date
    Jun 30, 2023
  • participants needed
  • sponsor
    University of Tennessee Health Science Center
Updated on 16 February 2022
ct scan
arterial occlusion
acute stroke


Placing the head of bed (HOB) at 0-degrees has been shown in small studies to improve blood flow to the brain in patients with ischemic stroke caused by large artery occlusions, thereby reducing stroke symptom worsening. This simple yet potentially impactful intervention has yet to be tested in a large clinical trial in hyperacute large artery ischemic stroke patients, but may provide nurses with a powerful contribution to acute stroke care that is capable of preventing worsening of stroke symptoms and promoting stabilization. Because stroke is the leading cause of preventable long-term disability in adults, this study may show that simple methods such as 0-degree HOB positioning should be considered one of the very first actions taken in the emergent management of acute ischemic stroke patients.


Positioning of the patient during hyperacute ischemic stroke (AIS) treatment is an important, yet understudied aspect of nursing care that could impact the course of treatment and clinical outcome. Since 1968, clinical symptom worsening in AIS patients has been documented with the head of bed (HOB) elevated to 30 degrees or higher, while clinical improvement or symptom stability has been noted with zero degree HOB positioning. Mechanisms for zero degree HOB clinical improvement include favorable gravitational blood flow conditions and recruitment of collateral blood channels, while in the case of treatment with clot-busting medications, increased blood flow may allow more medication to reach occluded arteries facilitating clot breakdown. Despite this, there is currently divide within the clinical community about what position is best for patients, although it has been argued that zero degree head positioning should be among the first steps taken to improve blood flow to the brain and prevent stroke symptom worsening. The investigators have shown that elevated ICP is absent in early AIS, and that pneumonia is rare using these piloted methods. However, no large clinical trial has examined efficacy and safety of zero degree HOB positioning within hyperacute large vessel occlusion (LVO) ischemic stroke patients with potentially viable brain tissue, leaving the acute stroke community confused as to what constitutes best practice. ZODIAC is a prospective randomized open blinded endpoint (PROBE) clinical trial of head positioning to determine if zero degree HOB positioning during the early phase of hyperacute LVO ischemic stroke management prevents neurological symptom worsening. Mechanical thrombectomy (MT) eligible patients (n=182) will be randomized to one of two groups: 1) Zero degree HOB positioning; or, 2) thirty degree HOB positioning. The hypothesis is that optimal HOB position can be determined by early neurological symptom worsening during the intervention (Aim 1) prior to initiation of the thrombectomy procedure, and the investigators propose that real-time deterioration may be a surrogate measure for decreased downstream perfusion, potentially impacting viability of brain at risk for infarction. Aim 2 will confirm that use of zero degree HOB positioning for AIS is safe. Use of this nursing measure holds significant promise as an innovative adjunct method to improve AIS symptoms, and ultimately reduce disability.

Condition Ischemic Stroke
Treatment Head of Bed Positioning
Clinical Study IdentifierNCT03728738
SponsorUniversity of Tennessee Health Science Center
Last Modified on16 February 2022


Yes No Not Sure

Inclusion Criteria

Ischemic stroke symptoms consistent with large artery occlusion
Baseline standard of care non-contrast head CT (or MRI) negative for hemorrhage or mass-effect
Evidence of arterial occlusion on standard of care CT angiography or MR angiography
Favorable neuroimaging (Alberta Stroke Program Early Computed Tomography Score [ASPECTS] > 6 in anterior circulation stroke; not applicable in posterior circulation stroke)
Ordered treatment with mechanical thrombectomy
Pre-stroke baseline modified Rankin Score (mRS) < 1
Ability to enroll, randomize and begin the intervention within the Emergency Department

Exclusion Criteria

Non-English speaking subjects will be excluded due to use of English language instruments (modified Rankin Scale [mRS] & NIHSS) and English speaking investigators
Pregnancy or suspicion of pregnancy
Evidence or suspicion of vomiting any time prior to consent which could predispose to aspiration pneumonia and therefore confound determination of protocol safety
Anticipated palliative care referral
Evidence of evolving malignant infarction on admission noncontrast CT (or MRI)
Need for intubation with mechanical ventilation, or non-invasive ventilatory support with either bi-level positive airway pressure (BiPAP) or continuous positive airway pressure (CPAP)
Inability to tolerate zero-degree positioning due to congestive heart failure, preexisting pneumonia, chronic obstructive pulmonary disease, or other medical condition
Admission chest radiograph positive for pleural effusion, pulmonary edema, pneumonia, or other pulmonary condition that may confound determination of protocol safety
Abnormal breath sounds on admission assessment that may confound determination of protocol safety
Lack of a telephone and/or permanent address predisposing patients to be lost to follow up
Enrollment in another clinical trial that may affect our primary or secondary endpoints
In the absence of a consenting legal next of kin, any medical, psychological, cognitive, social or legal condition that would interfere with informed consent and/or capacity to comply with all study requirements, including the necessary time commitment
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