Article, Respiratory Medicine

Physiological effects of a spit sock

a b s t r a c t

Objectives: Healthcare providers and Law enforcement utilize spit socks to prevent exposure to communicable diseases transmitted by bodily fluid projection from agitated individuals. There are cases in which death is re- ported due to breathing being limited by a spit sock. There are no formally published studies on their use and safety. The aim of this study was to evaluate whether wearing a spit sock causes a clinically significant impact on breathing.

Methods: Subjects sat with the spit mask over their heads for 15 min and their vital signs and ventilatory param- eters were recorded after 5 min, 10 min and 15 min. Data were compared to baseline using Student’s t-test with 95% confidence intervals using SPSS.

Results: The median age of the 15 subjects was 28 years and 53% were male. There was no significant difference between baseline and wearing the spit sock for 5, 10 or 15 min for heart rate (p = 0.250, p = 0.181, p = 0.546), oxygen saturation (p = 0.334, p = 1.00, p = 0.173), end-tidal pCO2 (p = 0.135, p = 0.384, p = 0.187), and di- astolic blood pressure (p = 0.485, p = 0.508, p = 0.915). The respiratory rate was not significantly different after 5 and 10 min (p = 0.898, p = 0.583), but decreased at 15 min (p = 0.048). The systolic blood pressure was lower after 5 and 10 min (p = 0.028, p = 0.045), but not significantly different at 15 min (p = 0.146). No subject indi- cated distress nor did the study need to be terminated due to pre-determined concerning vital signs or ventila- tory parameters.

Conclusions: In healthy subjects there were no Clinically significant changes in the physiologic parameters of breathing while wearing a spit sock.

(C) 2018

Introduction

Spit socks are mesh hoods that can be placed over the head of an in- dividual to reduce the transmission of saliva or blood via spitting. Healthcare providers, EMS personnel and law enforcement often utilize spit socks to reduce the risk of bodily fluid exposure from agitated indi- viduals. Over the last few years, the use of spit socks has increased. Ac- cording to the San Diego Sheriff’s Department’s Use of Force Statistical Report 2014-2015 and 2015-2016, spit socks were utilized by their de- partment 219 times in 2014, 305 times in 2015, and 394 times in 2016 [1,2]. There has also been a controversial increase in implementation of spit hoods in the UK and Germany [3-6]. The nature of the controversy surrounding spit socks, especially in the light of recent media coverage of alleged police brutality, revolves not only around the public image and psychological effect of placing a spit sock on an individual, but also their safety and potential effect on breathing [3,4]. There have

* Corresponding author at: 200 W. Arbor Dr. #8676, San Diego, CA 92103, United States.

E-mail addresses: [email protected] (M. Lutz), [email protected] (C.M. Sloane), [email protected] (E.M. Castillo), [email protected] (J.J. Brennen), [email protected] (C.J. Coyne), [email protected] (S.L. Swift), [email protected] (G.M. Vilke).

been a few anecdotal judicial cases in which subject death was sug- gested to be due to asphyxiation by a spit sock [7,8]. During these cases, it has been proposed that the spit sock becomes saturated to the point of covering the holes in the mesh of the spit sock so that the sub- ject is not able to adequately ventilate or draw air through the spit sock. There have also been allegations that spit socks have caused ventilatory issues and asphyxiation without any spit or saliva on them [7]. There are no formally published studies evaluating whether or not exposure of a spit sock alone or with spit or fluid of a similar viscosity or even denser viscosity can prevent a subject from breathing or successfully drawing a breath. The aim of this pilot study is to evaluate whether a spit sock has an impact on breathing and ventilatory parameters in a healthy adult subject.

Methods

Study design

This was a prospective study evaluating the effect of spit sock appli- cation on vital signs and ventilatory parameters of healthy adult

https://doi.org/10.1016/j.ajem.2018.09.050

0735-6757/(C) 2018

292 M. Lutz et al. / American Journal of Emergency Medicine 37 (2019) 291293

volunteers, compared to baseline parameters without wearing the spit sock. The study was reviewed and approved by our Institutional Review Board. All participants provided written informed consent.

Study setting and population

This study was performed at an academic medical center using vol- unteer subjects. Inclusion criteria included individuals between the ages of 18-65 years and exclusion criteria were: being claustrophobic or pregnant, and those who did not wish to undergo the study by personal choice.

Study protocol

After consent, descriptive data were gathered from the subject, in- cluding age, gender, weight, height, and medical conditions. All females underwent urine pregnancy testing and would have been excluded if the test had come back positive. The subject was then placed in a seated position on a chair. A buzzer was placed near his or her dominant hand that the subject was instructed to press should he or she experience dis- tress that could not be verbalized. The spit mask was then applied over the subject’s head. The spit sock used for the study was the black MTR Spit Hood (SKU: MTR-SS285W). The subject sat with the spit mask for 15 min. The study would have been stopped and the mask removed if the subject pushed the buzzer, if the O2 sat dropped below 91%, if the ETCO2 went 10 points above baseline, if the heart rate went beyond 110 bpm or dropped below 50 bpm (unless baseline heart rate was below 60 bpm – in those subjects the study was stopped if the heart rate dropped 10 bpm below baseline).

Table 1

Characteristics of study subjects (n = 15).

Mean (SD)

Range

Age (years)

30.9 (9.2)

19-51

Weight (kg)

71.7 (15.2)

49.9-102

Height (m)

1.73 (0.1)

1.57-1.93

Body mass index (kg/m2)

23.7 (3.2)

19.3-29.4

0.250, p = 0.181, p = 0.546 respectively), oxygen saturation (p = 0.334, p = 1.00, p = 0.173 respectively), end-tidal pCO2 (p = 0.135, p

= 0.384, p = 0.187 respectively), and diastolic blood pressure (p = 0.485, p = 0.508, p = 0.915 respectively). For respiratory rate, the dif- ference between baseline rate and rate after spit sock application was not significant after 5 and 10 min (p = 0.898 and p = 0.583, respec- tively), and significantly decreased at 15 min (p = 0.048). The systolic blood pressure was significantly lower after 5 and 10 min of spit sock application (p = 0.028 and p = 0.045, respectively), but not signifi- cantly different at 15 min (p = 0.146). No subject pressed the buzzer to indicate distress and in no subject did the study have to be termi- nated due to pre-determined concerning vital signs or ventilatory parameters.

Table 2

Effect of spit sock exposure on vital signs and ventilatory parameters (n = 15).

Baseline 5 min 10 min 15 min

Measures

Heart rate (bpm)

Mean (SD) 79 (11.8) 76.9 (11.5) 76.1 (7.8) 77.9 (9.5)

Each subject’s vital signs and ventilatory parameters, including oxy- gen saturation, heart rate, blood pressure, respiratory rate, and end-tidal

Change from baseline (SD)

/ -2.1 (6.9) -2.9 (8.1) -1.1 (6.7)

pCO2, were recorded after the subject sat down on a chair prior to the intervention and then 5, 10, and 15 min after application of the spit sock. Ventilatory measures, including oxygen saturation, heart rate, re- spiratory rate, and end-tidal pCO2 were obtained using a Smith’s Medi- cal Capnocheck II Hand-Held Capnograph/Oximeter.

Data analysis

Data were entered in an Excel (Microsoft Corp., Redmond, WA) da- tabase for analysis. Analyses were performed using SPSS Version 24.0 (SPSS Inc., Chicago, IL). Student’s t-test was utilized to measure differ- ences in means between vital signs and ventilatory parameters at base- line and after wearing the spit sock for 5 min, 10 min and 15 min. In our analysis, p b 0.05 was considered to represent plausible, significant differences.

Results

Characteristics of study subjects

A total of fifteen volunteers completed the study, 53% were male. No subject was screened out prior to or after consent. Two subjects re- ported a medical history of mild intermittent asthma. No other medical conditions were reported. Other subjeCT characteristics are reported in Table 1.

Main results

Table 2 shows the mean vital signs and ventilatory parameters at baseline without the spit sock and at 5, 10, and 15 min after spit sock ap- plication. There was no significant difference between baseline and while wearing the spit sock for 5, 10 or 15 min for heart rate (p =

95% CI / -5.9, 1.7 -7.4, 1.5 -4.8, 2.6

p-Value / 0.250 0.181 0.546

O2 sat (%)

Mean (SD)

97.5 (1)

97.3 (1)

97.5 (0.6)

97.1 (1.1)

Change from baseline

/

-0.2 (0.8)

0.0 (0.9)

-0.3 (0.9)

(SD)

95% CI

/

-0.6, 0.2

-0.5, 0.5

-0.8, 0.2

p-Value

/

0.334

01.000

0.173

Et pCO2 (9 mm Hg) Mean (SD)

38.5 (4.7)

37.3 (5)

37.9 (5.1)

37.6 (6)

Change from baseline

/

-1.2 (2.9)

-0.7 (2.9)

-0.9 (2.6)

(SD)

95% CI

/

-2.8, 0.4

-2.3, 0.9

-2.4, 0.5

p-Value

/

0.135

0.384

0.187

RR (breaths/min)

Mean (SD)

16.6 (5.5)

16.8 (5.7)

17.3 (5.5)

14.1 (4.7)

Change from baseline

/

0.2 (6.0)

0.7 (4.6)

-2.5 (4.5)

(SD)

95% CI

/

-3.1, 3.5

-1.9, 3.2

-5.0, 0.0

p-Value

/

0.898

0.583

0.048?

SBP (mm Hg)

Mean (SD)

125.6

120.4

119.8

121.1

(15.4)

(15.1)

(15.4)

(13.7)

Change from baseline

/

-5.2 (8.2)

-5.8 (10.2)

-4.5 (11.4)

(SD)

95% CI

/

-9.8, -0.6

-11.5, -0.1

-10.9, 1.8

p-Value

/

0.028?

0.045?

0.146

DBP (mm Hg) Mean (SD)

84 (12.1)

82.3 (12.1)

82.1 (12.3)

83.7 (10.9)

Change from baseline

/

-1.7 (9.0)

-1.9 (11.0)

-0.3 (9.5)

(SD)

95% CI

/

-6.7, 3.3

-8.0, 4.2

-5.5, 5.0

p-Value

/

0.485

0.508

0.915

Bpm = beats per minute, SD = standard deviation, CI = confidence interval, Et pCO2 = end-tidal pCO2, RR = respiratory rate, SBP = systolic blood pressure, DBP = diastolic blood pressure.

p-Values and CI are given for comparison between baseline and indicated time after spit sock application.

* Significant difference between baseline and after spit sock application (p b 0.05).

M. Lutz et al. / American Journal of Emergency Medicine 37 (2019) 291293 293

Discussion

Spit socks are generally considered to be a safe method to provide protection to law enforcement and medical providers from spit and other bodily fluids from an agitated or altered individual. There are a wide variety of spit socks and there is no standardized material, design or vendor. Spit sock designs vary from full mesh to plastic or textile cov- ering over the mouth area. The spit sock used in this study was full mesh, a more commonly used design carried on police patrol cars. There are no national guidelines or protocols for the application of spit socks to an individual, but usually local police guidelines permit applica- tion of the spit sock to an individual if the individual has spit (or other- wise purposefully projected bodily fluids) onto a person, or the police officer believes the person will spit on a person [10-13]. Many, but not all local guidelines also state that the individuals should be closely mon- itored and not be left alone, and that the spit hood is to be removed if the individual has difficulty breathing or is vomiting [10-12]. A PubMed search of the key terms “spit sock” or “spit hood” or “spit restraint” re- veals only one publication from AIDS Policy Law, May 2004, which de- tails an order to uphold the use of a spit hood for an HIV positive man to wear in court [9]. There are no other research cases, reviews or proto- cols detailing the use of spit hoods or spit socks in the literature.

Many of the anecdotal litigation cases involved situations in which

the spit sock was applied, or not removed, when the person in custody was vomiting, and/or bleeding from the face or had expressed breathing difficulties, although there are some cases in which simple application of the spit sock alone is said to have caused breathing difficulties [7,8]. The suggested mechanism is a blocking off of some of the apertures in a spit sock by spit or other body fluids. It is suggested that the spit sock becomes saturated to the point of covering the holes of the spit sock so that the subject is not able to adequately ventilate or draw air through the spit sock. There are no formal published studies evaluating whether or not exposure of a spit sock alone or with spit or fluid of a similar viscosity can prevent a subject from breathing or successfully drawing a breath. This study served as a pilot study to evaluate whether a spit sock has an impact on ventilation in a comfortably resting, healthy, adult subject. The study demonstrated no changes in heart rate, oxygen saturation, end-tidal CO2, and diastolic blood pressure. After wearing the spit sock for 15 min, the respiratory rate was slightly decreased compared to baseline from 16.6 breaths/min to 14.1 breaths/ min, which would not be considered a clinically significant change. The systolic blood pressure decreased from a baseline of 125.6 mm Hg to

120.4 mm Hg and 119.8 mm Hg at 5 and 10 min after spit sock applica- tion, respectively. This change also does not represent a clinically signif- icant change. No subject in this study pressed the buzzer to indicate distress and the vital signs and ventilatory parameters did not reach a pre-determined concerning change that would have resulted in re- moval of the spit sock.

Limitations

This study is a pilot study with a small sample size of 15 subjects, and as such, a large effect size is needed to recognize statistical significance. In addition, the subjects were young, healthy non-pregnant volunteers, whereas subjects in the field may have chronic conditions, claustropho- bia, be pregnant or have illicit substance ingestion. Donning of the spit sock could potentially cause excessive disorientation and anxiety in cer- tain individuals, especially if there is an underlying medical or mental health condition, or if the subject is a child [14]. Furthermore, the cir- cumstances of the study do not replicate circumstances in which spit socks are usually used, which are situations of conflict with law enforce- ment or health care personnel, with the subject often already restrained, possibly injured, lying down, and with spit or other body fluids on the spit sock. There is also a wide variety of spit socks in use and there are no designated standards or requirements. Since there is no standard

spit sock material or design, it possible for different spit socks to present varying degrees of aperture size and ventilation ability.

Conclusions

In healthy subjects, there were no clinically significant changes in the physiologic parameters of breathing while wearing a spit sock. This study offers a foundation for further research into the use and safety of spit socks. Future studies should explore the Physiologic effects of spit socks on exerted and restrained subjects, and of spit socks with partially occluded apertures, as this resembles other real world scenarios.

Funding sources/disclosures

Funding was provided by the general research fund of the Depart- ment of Emergency Medicine, UC San Diego Medical Center. This re- search did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. Declarations of interest: none.

Acknowledgments

Department of Emergency Medicine, UC San Diego Medical Center; University of California San Diego School of Medicine.

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