Response to: The prone position paradox

I appreciate the response to my article by Kroll et al.^1,2 My review article centered on studies showing the effects of prone restraint on respiratory physiology and cardiac output and how it places individuals with acute behavior disturbance and metabolic acidosis at risk for prone restraint cardiac arrest (PRCA) but I will address the topics Kroll et al. were focused on.

Kroll et al. first state the risks of non-firearm arrest-related death (ARD) is very low and comparable to an elective ablation procedure for atrial fibrillation in a compliant and consenting patient. ³ Physicians and scientists are constantly studying ways to improve success and reduce risks of medical and procedural treatments. Despite the very low mortality rate with ablation, complications and death following this procedure have been further reduced by improved technology, technique, and experience. ⁴ Similarly, it would seem incomprehensible that the public and law enforcement officers (LEO) who deal with nonconsenting individuals would not want to further reduce the risks of ARD.

Kroll et al. note that three prospective studies^5–7 have shown zero incidence of death with the use of prone restraint, however, the population studied in these studies was much smaller than retrospective analyses from Ontario, Canada; ⁸ Los Angeles; ⁹ England and Wales; ¹⁰ and the Netherlands, ¹¹ where deaths associated with prone position occurred 2–3 times a year. Two of the prospective studies^5,7 reported only the final resting position of a subject once physical control was achieved, with length of time in prone position and weight force not reported. Ross ⁶ reported that arrestees remained in the prone position for an estimated 1 to 5 min but does not report the average time. The prospective studies were approved by the policing agencies with officers submitting study data collection forms after each use of force event or shift. It is possible that LEO awareness, reminders and education could have limited and reduced time in prone restraint, which translated to no ARD.

Kroll et al. point out recent trials demonstrating that prone positioning improved oxygenation in patients with acute respiratory distress syndrome (ARDS) caused by COVID-19 who are awake and not intubated. ³ We understand from multiple studies that prone position causes a decrease in ventilation in healthy awake subjects. ¹ ARDS causes respiratory failure due to inflammation and noncardiogenic pulmonary edema that restricts oxygen from entering the blood system, with secondary hypoxia due to poor perfusion. ¹² In ARDS, prone positioning improves gas exchange by improving ventilation/perfusion mismatch. By comparison, individuals subjected to prone restraint do not have diffuse lung disease with no issues in gas exchange, thus a beneficial impact of prone position should not be expected. Stating better gas exchange as a reason to adopt prone restraint is ill-advised.

Kroll et al. state that some sudden deaths unexplained by conventional autopsy may be due to unidentified genetic abnormalities that may provoke ARD in prone restraint after physical or psychological stress. My article reviewed these alternative theories including genetic channelopathies catecholaminergic polymorphic ventricular tachycardia and QT prolongation, which elicit ventricular arrhythmias. Pulseless electrical activity and asystole have been the primarily identified arrhythmias noted with PRCA due to drug, psychological and physical induced metabolic acidosis exacerbated by inadequate ventilation and a decrease in cardiac output from prone restraint.

Kroll et al. review the benefits and rational for the use of prone restraint while handcuffing an uncooperative subject and are critical that I did not offer an alternative position. This topic would be better aimed at police policy makers and organizations that recommend avoiding and limiting prone restraint in individuals with behavioral disturbances. ¹ The International Chiefs of Police Association (ICPA)—the oldest, largest, and most prestigious policing organization in the world—has directed departments to limit the use of prone restraint and to roll a subject onto their side or to a sitting position as soon as possible to facilitate breathing. ¹³ Many police departments across the United States have adopted these policies including moving a subject out of prone position once handcuffed. ¹³

Regarding the death of George Floyd, I believe that Kroll et al. misconstrue some of the facts of the case. First, Dr Jonathan Rich, the only cardiologist to give testimony during Officer Derek Chauvin's trial, was correct when he stated “with a high degree of medical certainty that George Floyd did not die from a primary cardiac event.” ¹⁴ Second, Officer Chauvin placing his leg on Mr Floyd's posterior neck would not have significantly occluded Mr Floyd's trachea to cause suffocation. Rather, the combination of Officer Chauvin's leg keeping Mr Floyd in a prone position as two other officers placed weight on Floyd's lower back and legs led to death by PRCA. If the officers had followed police policy of avoiding or limiting prone restraint in a handcuffed individual, it is highly probable that George Floyd would be alive today.