Further study on the physiological effects of an alternative spit mask

Do Saliva-Saturated Spit Hoods Interfere With Ventilation?

ABSTRACT

Spit hoods are used by law enforcement, officers in correctional facilities, and medical personnel during the restraint of agitated subjects that are actively spitting to prevent the transmission of droplet-transmitted pathogens. We could find no studies reporting on the time course of normal breathing to clear saliva from such a saturated spit hood. We purchased samples of 3 popular spit hood models and applied a section over the output of a pneumatic test system. We used a digital anemometer, digital manometer, and an inline controllable fan for back pressure and flow. The pressure was 3 mm Hg to match quiet breathing. The tested area was saturated with artificial saliva, and air pressure was applied while we recorded the pressure and airflow. Within 5 seconds, the spit hoods all cleared sufficient artificial saliva to allow 1 m/s of airflow, which exceeds that of an N95 mask with similar pressure. Commonly used spit hoods offer very low resistance to breathing even after being initially saturated with artificial saliva. Our results do not support the hypothesis that a saliva-filled spit hood might contribute to death.

Physiological Effects of a Spit Restraint Device Saturated With Artificial Saliva

BACKGROUND

Spit restraint devices, also referred to as spit hoods, spit masks, or spit socks, are used by law enforcement and medical personnel to minimize transmission of communicable disease from bodily fluids from agitated individuals. Several lawsuits have implicated spit restraint devices as contributing to the death of individuals who are physically restrained by means of asphyxiation due to saturation of the mesh restraint device with saliva.

OBJECTIVES

This study aims to evaluate whether a saturated spit restraint device has any clinically significant effects on the ventilatory or circulatory parameters of healthy adult subjects.

METHODS

Subjects wore a spit restraint device dampened with 0.5% carboxymethylcellulose, an artificial saliva. Baseline vitals were taken, and a wet spit restraint device was then placed over the subject's head, and repeat measurements were taken at 10, 20, 30, and 45 min. A second spit restraint device was placed 15 min after the first. Measurements at 10, 20, 30, and 45 min were compared with baseline using paired t-tests.

RESULTS

The mean age of 10 subjects was 33.8 years, and 50% were female. There was no significant difference between baseline and while wearing the spit sock for 10, 20, 30, and 45 min for the measured parameters including heart rate, oxygen saturation, end-tidal CO₂, respiratory rate, or blood pressure. No subject indicated respiratory distress or had to terminate the study.

CONCLUSIONS

In healthy adult subjects, there were no statistically or clinically significant differences in ventilatory or circulatory parameters while wearing the saturated spit restraint.

Pneumatic Impedance of Spit Socks and N95 Masks: The Applicability to Death Investigation

INTRODUCTION

Restrained subjects often spit on law enforcement and corrections officers and medical responders. Based on the droplet-transmitted risk of COVID-19, such spitting could be considered a potentially life-threatening assault. Officers commonly use "spit socks" over the head and neck of spitting subjects to reduce this risk. The pneumatic impedance of such socks has not been published, so this remains an open issue for arrest-related death investigation.

METHODS

We purchased samples of 3 popular spit sock models, 3 insect-protecting "bug" socks and hats, 3 N95 masks, a standard 3-ply surgical mask, and a common dust mask. We used a BTmeter model BTN8468 digital anemometer, an HTI model HT-1890 digital manometer, and an AC Infinity Cloudline model S6 inline controllable fan to measure air flow versus pressure drop. We compared the curves graphically and also calculated a pneumatic pseudo-impedance by dividing the pressure drop by the air velocity.

RESULTS

The spit and bug socks allowed nearly maximum airflow with minimal pressure (≤1 mm Hg), whereas none of the masks allowed greater than 2 m/s of airflow at maximum pressure of 3 mm Hg. All of the spit and bug masks were grouped together with the lowest pneumatic impedances, whereas all of the N95 masks were grouped together with the highest values. The dust mask and surgical mask were in between with the dust mask closer to the spit and bug masks, whereas the surgical mask was closer to the N95 masks in impedance.

CONCLUSIONS

Commonly used spit socks offer nearly zero resistance to breathing. The highest resistance spit sock was still 100 times better than the best N95 mask for airflow during inhalation. Our results do not support the occasional hypothesis that spit socks might contribute to an arrest-related death.

Prevalence and correlates of spitting on police officers: New risks in the COVID era

OBJECTIVES

Spitting is an occupational hazard of police work with increased risk due to the COVID-19 pandemic. We sought to calculate the prevalence of spitting on police officers in use of force incidents, as well as the demographic and situational factors associated with spitting.

METHODS

Data on spitting were compiled from more than 10,000 use of force incidents occurring at 81 agencies in eight different states in the US.

RESULTS

Spitting occurred in 3.6% of cases. Female and younger subjects and those using drugs and/or alcohol are more likely to spit on officers. Spitting is more likely to occur in incidents of longer duration, when officers use less force relative to subject resistance, when subjects are assaultive or engage in self-harm, and when subjects are hobbled.

CONCLUSIONS

Spitting on officers is common and may now constitute a significant work hazard. Implications for police practice are discussed.