# Head Down Tilt 15° to Increase Collateral Flow in Acute Ischemic Stroke: Rationale and Study Protocol > **Author:** Benjamin Caplan, MD (ABFM Board Certified, MA Lic. #240562, NPI: 1962722637) > **Publisher:** CED Clinic (https://cedclinic.com) > **Canonical URL:** https://cedclinic.com/head-down-tilt-ischemic-stroke-collateral-flow/ > **Published:** 2026-04-27T04:02:45-04:00 | **Last Modified / Clinically Audited:** 2026-09-28T16:01:33-04:00 > **Clinical Summary:** Explore head down tilt ischemic stroke therapy to improve collateral blood flow and outcomes in acute ischemic stroke patients treated with mechanical thrombectomy. --- CED Clinical Relevance  #80High Clinical Relevance  Strong evidence or policy relevance with direct clinical implications. 🔬 Evidence Watch  |  CED Clinic Journal Stroke (Hoboken, N.J.) Study Type [Randomized Trial](https://cedclinic.com/cannabis-cannabinoids-therapeutic-applications-review/) Population Human participants Why This Matters This item covers developments relevant to [cannabis medicine](https://cedclinic.com/essential-oils-industrial-hemp-antimicrobial-benefits/) and [clinical practice](https://cedclinic.com/cannabis-reproductive-health-women-clinical-evidence/). Clinicians monitoring evidence in this area should review the source material. Clinical Summary Collateral blood flow is a critical determinant of successful recanalization in acute ischemic stroke caused by large vessel occlusion. Head down tilt -15° (HDT15), similar to Trendelenburg positioning, is a simple, low-cost positional therapy that may augment cerebral collateral blood flow and penumbral survival. The aim of the study is to assess the safety, feasibility, and efficacy of HDT15 in improving cerebral collateral circulation and clinical outcomes in patients with large vessel occlusion-acute ischemic stroke treated with mechanical thrombectomy (MT). The DOWN-SUITE trial (Head Down Tilt 15° to Increase Collateral Flow in Acute Ischemic Stroke) is a multicenter, randomized, open-label, phase 2a/b clinical trial with blinded outcome assessment, conducted across 7 Italian stroke centers. A total of 118 patients with acute ischemic stroke due to M1 segment middle cerebral artery occlusion will be randomized 1:1 in the emergency department to receive HDT15 or standard positionin Dr. Caplan’s Take “This is a development worth tracking. The clinical implications will become clearer as more evidence accumulates.” Clinical Perspective 🧠 Clinicians should review this item in the context of their current practice and patient population. 💬 Join the Conversation Have a question about how this applies to your situation? [Ask Dr. Caplan →](https://benjamincaplan.com/ask-dr-caplan) Want to discuss this topic with other patients and caregivers? [Join the forum discussion →](https://cedclinic.com/interact/discussion-forums/forum/cannabis-industry/) Have thoughts on this? Share it: [X Share on X](https://twitter.com/intent/tweet?text=Just%20read%20this%20on%20CEDclinic.com%3A%20Head%20Down%20Tilt%2015%C2%B0%20to%20Increase%20Collateral%20Flow%20in%20Acute%20Ischemic%20Stroke%3A%20Rationale%20and%20Study%20Protoco...%20%40drcaplan&url=https%3A%2F%2Fcedclinic.com%2Fhead-down-tilt-15-to-increase-collateral-flow-in-acute-ischemic-stroke-rati%2F)[in Share on LinkedIn](https://www.linkedin.com/sharing/share-offsite/?url=https%3A%2F%2Fcedclinic.com%2Fhead-down-tilt-15-to-increase-collateral-flow-in-acute-ischemic-stroke-rati%2F)[🦅 Share on BlueSky](https://bsky.app/intent/compose?text=Just%20read%20this%3A%20Head%20Down%20Tilt%2015%C2%B0%20to%20Increase%20Collateral%20Flow%20in%20Acute%20Ischemic%20Stroke%3A%20Rationale%20and%20Study%20Protoco...%20via%20%40drcaplan.bsky.social%20https%3A%2F%2Fcedclinic.com%2Fhead-down-tilt-15-to-increase-collateral-flow-in-acute-ischemic-stroke-rati%2F)[📷 Follow on Instagram](https://www.instagram.com/drbenjamincaplan)[📝 Read more on Substack](https://doctorapprovedcannabis.substack.com/)[🔔 Subscribe via RSS](https://cedclinic.com/feed/) 📰 Source: [https://pubmed.ncbi.nlm.nih.gov/41815317/](https://pubmed.ncbi.nlm.nih.gov/41815317/) Table of Contents - [FAQ](#FAQ)[What is head down tilt 15 degrees in stroke care?](#What_is_head_down_tilt_15_degrees_in_stroke_care) - [Why does collateral blood flow matter in acute ischemic stroke?](#Why_does_collateral_blood_flow_matter_in_acute_ischemic_stroke) - [What is the DOWN-SUITE trial trying to find out?](#What_is_the_DOWN-SUITE_trial_trying_to_find_out) - [How is the DOWN-SUITE trial designed, and how many patients will enroll?](#How_is_the_DOWN-SUITE_trial_designed_and_how_many_patients_will_enroll) - [Related](#Related) ## FAQ ### What is head down tilt 15 degrees in stroke care? HDT15 is a positional therapy in which the patient is tilted head down at 15 degrees, similar to Trendelenburg positioning. The article describes it as simple and low cost, and says it may augment cerebral collateral blood flow and penumbral survival in acute ischemic stroke. ### Why does collateral blood flow matter in acute ischemic stroke? Collateral blood flow is a critical determinant of successful recanalization in acute ischemic stroke caused by large vessel occlusion. That is the rationale for this trial: if HDT15 augments collateral flow, it might improve cerebral collateral circulation and clinical outcomes in patients treated with mechanical thrombectomy. ### What is the DOWN-SUITE trial trying to find out? The trial aims to assess the safety, feasibility, and efficacy of HDT15 in improving cerebral collateral circulation and clinical outcomes. It focuses on patients with large vessel occlusion acute ischemic stroke treated with mechanical thrombectomy, specifically those with occlusion of the M1 segment of the middle cerebral artery. ### How is the DOWN-SUITE trial designed, and how many patients will enroll? It is a multicenter, randomized, open-label, phase 2a/b trial with blinded outcome assessment, conducted across 7 Italian stroke centers. A total of 118 patients will be randomized 1:1 in the emergency department to receive either HDT15 or standard positioning. The publication presents the rationale and protocol, so the trial is planned rather than completed. [https://cedclinic.com/contact/](https://cedclinic.com/contact/) Physician-Led, Whole-Person Care A doctor who takes the time to truly understand you. Personal care that starts with listening and is guided by experience and ingenuity. 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[Read More](https://cedclinic.com/medical-cannabis-opioid-alternatives-reduce-rx-drug-use/) [What Cannabis Does to Your Brain in the First 24 Hours – Verywell Health](https://cedclinic.com/cannabis-brain-effects-evidence-first-24-hours/) Understand the acute effects of cannabis on brain function, providing context for neurological research and [clinical practice](https://cedclinic.com/cannabis-reproductive-health-women-clinical-evidence/). [Learn More](https://cedclinic.com/cannabis-brain-effects-evidence-first-24-hours/) [[Academic] Seeking Participants for Study on Cannabis + Sexual Health (18+, female, cannabis user)](https://cedclinic.com/cannabis-sexual-health-study-female-participants/) Join an academic study exploring cannabis and [sexual health](https://cedclinic.com/adolescent-cannabis-use-sexual-behavior-study/), contributing to expanding clinical knowledge in [cannabis medicine](https://cedclinic.com/essential-oils-industrial-hemp-antimicrobial-benefits/). [Join Study](https://cedclinic.com/cannabis-sexual-health-study-female-participants/) ### Related --- ### Verification & Medical Governance - **Lead Clinical Author:** Benjamin Caplan, MD - **Credentials:** Board Certified in Family Medicine (ABFM), Founder & CMO CED Clinic & CED Foundation, Author of *The Doctor-Approved Cannabis Handbook* (Penguin Random House). - **Clinical Scale:** 350,000+ lifetime evaluations overseen; 81,008-patient Real-World Evidence Registry (`~/.ced_rwe_vault.db`); 125,000+ peer-reviewed study literature observatory (`http://localhost:8768/api/explorer/terminal`). - **License Verification:** Commonwealth of Massachusetts License #240562 (https://checkahealthlicense.mass.gov/). - **NPI Registry:** 1962722637 (https://npiregistry.cms.hhs.gov/provider-view/1962722637). - **Ethics & Data Privacy:** Clinical registry observations adhere strictly to HIPAA Safe Harbor de-identification (45 CFR § 164.514(b)) and criteria for secondary research exemption under 45 CFR § 46.104(d)(4).