Journal of Correctional Health Care - April 2023 - 144

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KAPATOS AND SPOONEMORE
tomography (CT) findings of 137 asymptomatic patients,
they found that 61 (44.5%) had positive chest CT findings
(Parry et al., 2020). There are multiple suggested explanations
for the underlying pathophysiologic mechanisms
of silent hypoxemia.
Tobin et al. (2020) provided a comprehensive summary
of the various physiologic mechanisms for the absence of
subjective sensation of dyspnea including pulmonary
mechanisms, chemoreceptor's responsiveness to changes
in blood oxygen saturation (SpO2) and carbon dioxide saturations,
age-related physiologic changes, and shifts in the
oxyhemoglobin dissociation curve. Pathophysiologic
mechanisms that describe the finding of silent hypoxemia
have included robust discussion on the neuroinvasiveness
of SARS-CoV-2 in the brain stem and cortex (Chigr et al.,
2020; Coen et al., 2020; Li et al., 2020a, 2020b), microthrombotic
events in the lung (Negri et al.,2020), and
lung perfusion abnormalities (Herrmann et al., 2020).
A Cochrane systematic review of 22 studies reporting
on effectiveness and accuracy of universal screening concluded
that the evidence suggests that one-time screening
approaches with a symptom assessment, direct temperature
measurement, travel history, assessment for exposure
to known or suspected infected people, or
combined symptoms assessment with temperature measurement
may miss between 40% and 100% people
who are infected (Viswanathan et al., 2020).
Thus, the aim of this retrospective study is twofold: (a)
to report on vital sign characteristics of asymptomatic
COVID-19 infections, and (b) to use these findings to develop
and compare the effectiveness of various enhanced
screening algorithms.
Method
This retrospective case-control study, approved by the
Federal Bureau of Prisons Central Office and local institution
internal review boards, used electronic medical record
data from one Federal Bureau of Prisons institution
of incarcerated individuals who received laboratory testing
for COVID-19 from May 2020 through August 2020.
During this time, testing to confirm COVID-19 diagnosis
had been done via nasopharyngeal swabbing and off-site
laboratory PCR testing or the Abbott Rapid ID Now following
the instructions-for-use insert with laboratory
analysis performed on-site. Individuals with positive
tests had been placed on isolation precautions and individuals
with negative tests had been placed on quarantine
precautions.
Isolation precautions included once per shift (three
times per day) checks of symptoms and vital signs including
heart rate, oral thermometry, and pulse oximetry.
Requirements for removal from isolation were completion
of 14 days of isolation followed by two consecutively
negative lab tests 24 hours apart.
Quarantine precautions included a once daily check of
symptoms and vitals including heart rate and oral or temporal
thermometry. Pulse oximetry was not a requirement
for quarantine, thus not all quarantined individuals received
daily pulse oximetry. Requirements for removal
from quarantine were having 14 days of no symptoms,
being afebrile, and having two consecutive negative lab
tests at least 24 hours apart.
Individuals on isolation precautions were allowed to
take over-the-counter (OTC) antipyretic medications as
needed but quarantined individuals were not. Temperatures
had been taken with Welch Allyn SureTemp Plus
electronic thermometer. Pulse oximetry had been performed
with either the Medline High-Impact pulse oximeter
or the General Electric Ohmeda TuffSat.
The retrospective electronic medical records chart review
covered the 7-day period before the initial
COVID-19 lab test through the quarantine or isolation period.
It included data on age, body mass index (BMI),
past medical history (PMH), symptoms, OTC antipyretic
medication use, temperature, and SpO2. Symptoms included
the sensation of fever, chills, rigors, fatigue, dyspnea,
malaise, gastrointestinal symptoms, headache,
anosmia, runny or stuffy nose, sore throat, and cough.
Individuals with asymptomatic COVID-19 infections
(AC) were defined as those who reported no symptoms
immediately prior to and at no point during their isolation
period. Individuals with symptomatic COVID-19 infections
(SC) were defined as those with any symptom either
in the 7 days before or at any point during their isolation.
Individuals were placed into one of three groups: controls,
AC, or SC.
Excluded from the control group were individuals who
had a medical trip or hospitalization for any infectious
disease, acute cardiopulmonary condition, or exacerbation
of a chronic cardiopulmonary condition; those who
only received temporal thermometry; and those who
did not receive pulse oximetry. Excluded from all groups
were ''presumed positive'' infections.
Data on BMI, age, T-max defined as the maximum
recorded oral temperature, and SpO2-min defined as the
minimum recorded pulse oximetry for each group were
tested for normality with the Shapiro-Wilk test. A oneway
ANOVA was performed for parametric data. The
Kruskal-Wallis test for nonparametric data was performed
with Dunn's test for post-hoc analysis, which
was further adjusted with Holms method for familywise
error rate. Level of significance for all tests was
Journal of Correctional Health Care - April 2023

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