Controversy Sparks Anew Over Alleged Risks of Prone Positioning

Print Friendly, PDF & Email

A Canadian anesthesiologist has attempted to revive the controversy about alleged risks associated with the prone positioning of arrestees, only to draw an emphatic rebuke from a team of experts on the subject.

The physician is Alain Michaud, affiliated with a hospital in Roberval, Quebec. In published correspondence to the Journal of Forensic and Legal Medicine, he presents an argument sometimes advanced by plaintiffs’ attorneys in lawsuits against police involving arrest-related deaths. Namely, that applying pressure to the back of a proned-out, struggling suspect can compress the inferior vena cava blood vessel to the extent that blood from the legs and abdomen cannot get back to the heart, thus provoking a fatal cardiac disruption. He links the problem especially to individuals experiencing the excited delirium syndrome (ExDS).


The anesthesiologist challenges a study published earlier in the Journal which disputed the hypothesis that “weight force” applied to “the center of [a suspect’s] back” could cause a “sudden cardiovascular collapse” from significantly diminished blood return to the heart.

That study was too limited, Michaud argues, because, among other things, it did not adequately factor in the impact of physical exertion and psychological stress that invariably accompany ExDS encounters on the street.

Restraining a “hyperactive individual” in the prone position on a hard surface, he insists, “will impede free expansion of the chest and the abdomen” during inhalation and “may interfere with cardiopulmonary” function. Indeed, he says, even the weight of one knee applied to the back of a subject in the throes of ExDS “should alter the venus [blood] return significantly.”

Moreover, he writes, a “tight hogtie position could also reduce the venous return directly and indirectly by different mechanisms.”

Citing several papers written by others, Michaud concludes that the prone position should not be ruled out “as a contributing or precipitating factor in fatal ExDS.” Police, he says, should consider “developing restraint techniques that would not impede abdominal and chest expansion…in the lateral position.”

Michaud’s letter can be read in full, for a fee, by clicking here.


Four researchers involved in the study Michaud criticizes have fired back with a lengthy letter of their own. This team–Drs. Gary Vilke, Theodore Chan, Davut Savaser, and Tom Neuman–are physicians with the Dept. of Emergency Medicine at the University of California-San Diego.

“It is highly doubtful that Dr. Michaud’s letter would ever survive peer review,” they write, because he “relies on speculative theories” supported mainly by “reports of questionable applicability and no true experimental literature” and also “mischaracterizes many of his cited references,…often leaving out key details” to support his assertions.

The team points out that Michaud presents “no data” to support his claim that a single knee to the back of an excited delirium subject can significantly hamper blood flow. Although this is presented as fact, it appears in reality to be merely his “conjecture” and “speculation,” they write.

“Dr. Michaud completely fails to mention five other experimental papers,” in addition to their own study, “that directly contradict his thesis,” the researchers continue. These studies dealt with back weight up to 225 pounds, “with no reports of any adverse effects such as blood pressure drops” or heart distress symptoms “that would be consistent with marked reductions in cardiac output….

“To be blunt, Dr. Michaud ignores common sense. Were as little as one knee in the back sufficient to cause such a dangerous reduction in cardiac output, there would be significant death rates among rugby or football players.”

In contrast, the team notes, “there is now abundant evidence that even relatively minor degrees [of structural heart disease] is associated with an increased incidence of sudden death.” This risk factor, they conclude, is far more worthy of focus and exploration than the “unfounded and unsupported theory” of prone positioning adversely affecting blood flow.

The rebuttal can be accessed in full, for a fee, by clicking here.

An abstract of the study at the core of the Journal’s letter exchange can be viewed free of charge by clicking here. The title is “The effect of the prone maximal restraint position with and without weight force on cardiac output and other hemodynamic measures.”


Another observer weighing in recently on the alleged risks of prone positioning is Dr. Michael Graham, a professor of pathology at St. Louis University and chief medical examiner for the city of St. Louis. Graham includes the subject in a broad, 24-page review of factors often associated with arrest-related deaths published in Academic Forensic Pathology, the official journal of the National Assn. of Medical Examiners.

In light of existing research on the subject, Graham concludes that “in the vast majority of cases, it is unlikely” that the extent and duration of compression of an arrestee’s chest, back, or abdomen during prone positioning “are sufficient to cause or contribute to death.”

Sophisticated studies, he notes, have failed to confirm a risk of fatal breathing or cardiac problems induced by prone positioning with either hogtying or weight force.

In another section of his report, Graham explores research findings regarding the role of CEWs in arrest-related deaths, again concluding that no causal relationship has been established. He also describes relevant factors in deaths associated with neck restraint, excited delirium, and short-term physical exertion by suspects with the sickle cell trait.

A link for purchasing Graham’s full article, titled “Investigation of Deaths Temporally Associated with Law Enforcement Apprehension,” can be accessed by clicking here.

Leave a Reply


  • Privacy Policy

Privacy Policy

Effective date: January 06, 2019

Force Science Institute, Ltd. (“us”, “we”, or “our”) operates the https://www.forcescience.org/ website (hereinafter referred to as the “Service”).

This page informs you of our policies regarding the collection, use, and disclosure of personal data when you use our Service and the choices you have associated with that data. Our Privacy Policy for Force Science Institute, Ltd. is based on the Privacy Policy Template from Privacy Policies.

We use your data to provide and improve the Service. By using the Service, you agree to the collection and use of information in accordance with this policy. Unless otherwise defined in this Privacy Policy, the terms used in this Privacy Policy have the same meanings as in our Terms and Conditions, accessible from https://www.forcescience.org/

Information Collection And Use

We collect several different types of information for various purposes to provide and improve our Service to you.

Types of Data Collected

Personal Data

While using our Service, we may ask you to provide us with certain personally identifiable information that can be used to contact or identify you (“Personal Data”). Personally identifiable information may include, but is not limited to:

  • Email address
  • First name and last name
  • Phone number
  • Address, State, Province, ZIP/Postal code, City
  • Cookies and Usage Data

Usage Data

We may also collect information on how the Service is accessed and used (“Usage Data”). This Usage Data may include information such as your computer’s Internet Protocol address (e.g. IP address), browser type, browser version, the pages of our Service that you visit, the time and date of your visit, the time spent on those pages, unique device identifiers and other diagnostic data.

Tracking & Cookies Data

We use cookies and similar tracking technologies to track the activity on our Service and hold certain information.

Cookies are files with small amount of data which may include an anonymous unique identifier. Cookies are sent to your browser from a website and stored on your device. Tracking technologies also used are beacons, tags, and scripts to collect and track information and to improve and analyze our Service.

You can instruct your browser to refuse all cookies or to indicate when a cookie is being sent. However, if you do not accept cookies, you may not be able to use some portions of our Service. You can learn more how to manage cookies in the Browser Cookies Guide.

Examples of Cookies we use:

  • Session Cookies. We use Session Cookies to operate our Service.
  • Preference Cookies. We use Preference Cookies to remember your preferences and various settings.
  • Security Cookies. We use Security Cookies for security purposes.

Use of Data

Force Science Institute, Ltd. uses the collected data for various purposes:

  • To provide and maintain the Service
  • To notify you about changes to our Service
  • To allow you to participate in interactive features of our Service when you choose to do so
  • To provide customer care and support
  • To provide analysis or valuable information so that we can improve the Service
  • To monitor the usage of the Service
  • To detect, prevent and address technical issues

Transfer Of Data

Your information, including Personal Data, may be transferred to — and maintained on — computers located outside of your state, province, country or other governmental jurisdiction where the data protection laws may differ than those from your jurisdiction.

If you are located outside United States and choose to provide information to us, please note that we transfer the data, including Personal Data, to United States and process it there.

Your consent to this Privacy Policy followed by your submission of such information represents your agreement to that transfer.

Force Science Institute, Ltd. will take all steps reasonably necessary to ensure that your data is treated securely and in accordance with this Privacy Policy and no transfer of your Personal Data will take place to an organization or a country unless there are adequate controls in place including the security of your data and other personal information.

Disclosure Of Data

Legal Requirements

Force Science Institute, Ltd. may disclose your Personal Data in the good faith belief that such action is necessary to:

  • To comply with a legal obligation
  • To protect and defend the rights or property of Force Science Institute, Ltd.
  • To prevent or investigate possible wrongdoing in connection with the Service
  • To protect the personal safety of users of the Service or the public
  • To protect against legal liability

Security Of Data

The security of your data is important to us, but remember that no method of transmission over the Internet, or method of electronic storage is 100% secure. While we strive to use commercially acceptable means to protect your Personal Data, we cannot guarantee its absolute security.

Service Providers

We may employ third party companies and individuals to facilitate our Service (“Service Providers”), to provide the Service on our behalf, to perform Service-related services or to assist us in analyzing how our Service is used.

These third parties have access to your Personal Data only to perform these tasks on our behalf and are obligated not to disclose or use it for any other purpose.


We may use third-party Service Providers to monitor and analyze the use of our Service.

  • Google AnalyticsGoogle Analytics is a web analytics service offered by Google that tracks and reports website traffic. Google uses the data collected to track and monitor the use of our Service. This data is shared with other Google services. Google may use the collected data to contextualize and personalize the ads of its own advertising network.You can opt-out of having made your activity on the Service available to Google Analytics by installing the Google Analytics opt-out browser add-on. The add-on prevents the Google Analytics JavaScript (ga.js, analytics.js, and dc.js) from sharing information with Google Analytics about visits activity.For more information on the privacy practices of Google, please visit the Google Privacy & Terms web page: https://policies.google.com/privacy?hl=en

Links To Other Sites

Our Service may contain links to other sites that are not operated by us. If you click on a third party link, you will be directed to that third party’s site. We strongly advise you to review the Privacy Policy of every site you visit.

We have no control over and assume no responsibility for the content, privacy policies or practices of any third party sites or services.

Children’s Privacy

Our Service does not address anyone under the age of 18 (“Children”).

We do not knowingly collect personally identifiable information from anyone under the age of 18. If you are a parent or guardian and you are aware that your Children has provided us with Personal Data, please contact us. If we become aware that we have collected Personal Data from children without verification of parental consent, we take steps to remove that information from our servers.

Changes To This Privacy Policy

We may update our Privacy Policy from time to time. We will notify you of any changes by posting the new Privacy Policy on this page.

We will let you know via email and/or a prominent notice on our Service, prior to the change becoming effective and update the “effective date” at the top of this Privacy Policy.

You are advised to review this Privacy Policy periodically for any changes. Changes to this Privacy Policy are effective when they are posted on this page.

Contact Us

If you have any questions about this Privacy Policy, please contact us:

  • By email: support@forcescience.org
  • By visiting this page on our website: https://www.forcescience.org/contact
  • By phone number: 866-683-1944
  • By mail: Force Science Institute, Ltd.