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Evaluation and control of waste anesthetic gas in the
postanesthesia care unit within patient and caregiver
breathing zones
George W. Williams, MD
a,b
, Sam D. Gumbert, MD
a
, Evan G. Pivalizza, MBChB
a
, Tariq A. Syed, MS
c
,
Tyrone Burnett, Jr., BS
c
, Omar L. Mancillas, MD
c
, Leslie A. Vargas, MD
a
, Stephanie H. Ahn, BS
d
,
Chunyan Cai, PhD
e
, and Carin A. Hagberg, MD
c
a
Department of Anesthesiology, The University of Texas Health Science Center at Houston, McGovern Medical School, Houston, Texas;
b
Department of Neurosurgery, The University of Texas Health Science Center at Houston, McGovern Medical School, Houston,
Texas;
c
Department of Anesthesiology, Critical Care, and Pain Medicine, The University of Texas MD Anderson Cancer Center, Houston,
Texas;
d
Department of Surgery, The University of Texas Health Science Center at Houston, McGovern Medical School, Houston, Texas;
e
Department of Internal Medicine, The University of Texas Health Science Center at Houston, McGovern Medical School, Houston, Texas
ABSTRACT
This study (NCT02428413) evaluated waste anesthetic gas (WAG) in the postanesthesia care unit (PACU) and assessed the utility
of the ISO-Gard
V
R
mask in reducing nursing exposure to WAG. We hypothesized that WAG levels in the patient’s breathing zone
upon recovery would exceed the recommended levels, leading to increased exposure of the PACU nurses, with use of the ISO-
Gard mask limiting this exposure. A total of 125 adult patients were recruited to participate. Patients were randomized to receive
the standard oxygen delivery mask or the ISO-Gard face mask postoperatively. Continuous particulate concentrations were meas-
ured using infrared spectrophotometers placed within the patients’and nurses’6-inch breathing zone. Maximum WAG measure-
ments were obtained every 30 seconds, and the duration of maximum WAG >2 ppm and its proportion relative to the total
collection period were calculated. We observed a statistically significant difference in desflurane duration and proportion of max-
imum WAG >2 ppm in both patient and PACU nurse breathing zones. Therefore, patients and PACU nurses using routine care
were exposed to WAG levels >2 ppm during the 1-hour postoperative period, and the ISO-Gard mask effectively reduced the
amount of WAG detected in the immediate 1-hour postoperative recovery phase.
KEYWORDS Anesthetic pharmacokinetics; occupational safety; waste anesthetic gas
The scavenging of waste anesthetic gases (WAG) is
recommended by the Occupational Safety and
Health Administration in environments that use
anesthetic gases to reduce occupational exposure.
1
Exposure is determined by the concentration of agent in the
breathing zone, which the Occupational Safety and Health
Administration defines as an area surrounding the face
encompassing approximately 6 to 9 inches, and the length of
time that the agent is continuously inhaled.
2,3
Recommended levels apply anywhere that anesthetic agents
are delivered, as well as to the postanesthesia care unit
(PACU).
1
Though random room samples may indicate low
levels of WAG, the breathing zone of nurses near a recover-
ing patient may expose them to levels of anesthetic gases that
are above the National Institute of Occupational Safety and
Health’s (NIOSH) recommendation of concentrations
>2 ppm over a sampling period not to exceed 1 hour.
4
Recent studies suggest that potential PACU nurse exposure
to WAG is above NIOSH guidelines, given that such levels
in the patient breathing zone exceed these guidelines and
may occur as much as 49% of the time.
5,6
With this in
mind, exposure has been associated with multiple medical
Corresponding author: George W. Williams II, MD, FASA, FCCP, Departments of Anesthesiology and Neurosurgery, The University of Texas Health Science
Center at Houston, McGovern Medical School, 6431 Fannin, MSB 5.020, Houston, TX 77030-1501 (email: george.w.willams@uth.tmc.edu)
Color versions of one or more of the figures in the article can be found online at www.tandfonline.com/ubmc.
Received April 10, 2018; Revised July 10, 2018; Accepted July 16, 2018.
January 2019 43
PROC (BAYL UNIV MED CENT)
2019;32(1):43–49
Copyright #2019 Baylor University Medical Center
https://doi.org/10.1080/08998280.2018.1502017
problems including headaches, irritability, fatigue, nausea,
drowsiness, and difficulty with judgment and coordination.
3
Though operating rooms have implemented techniques to
decrease occupational exposure by scavenging WAG, thus
minimizing these potential health consequences, few studies
address the risk of PACU WAG exposure.
METHODS
The purpose of this observational prospective study was
to evaluate the use of the ISO-Gard
V
R
mask (Figure 1a),a
510(k) approved class II/nonsignificant risk device (cleared
by the US Food and Drug Administration). The study had
three primary objectives: (1) measure the level of WAG ema-
nating from the patient during the immediate 1-hour post-
operative recovery period in the PACU; (2) measure the level
of WAG within the PACU nurse’s breathing zone during
this immediate 1-hour postoperative recovery period; and (3)
validate the efficacy of the ISO-Gard mask in reducing nurse
exposure to WAG in the PACU.
The ISO-Gard ClearAir
TM
system (Teleflex Inc.,
Morrisville, NC) is a modified oxygen delivery face mask
that actively scavenges WAG exhaled by patients recovering
from surgery in the PACU, allowing for the delivery of sup-
plemental and/or therapeutic oxygen to patients to aid in
their recovery while simultaneously reducing the amount of
expelled WAG released to the work environment. Suction
for the scavenging of WAG through the attached corrugated
hose is provided by the institution’s regulated vacuum
source. Excess anesthetic gases can be removed with the use
of negative pressure through the facility’s central vacuum.
The interface of the machine is connected to the gas disposal
system of the facility, which vents the waste gases outside the
building away from any return ducts or open windows. The
mask can be used with or without the vacuum to function as
a standard oxygen delivery mask with an end-tidal carbon
dioxide monitoring port. The user may adjust the oxygen
flow rate and the vacuum rate as needed to deliver the
required oxygen and effectively scavenge the WAG.
Following institutional review board approval, informed
consent was obtained preoperatively from patients by key
study personnel. Once informed consent had been obtained,
the patient’s medical history and physical exam as docu-
mented by the anesthesiologist was reviewed, as well as the
planned anesthetic technique and estimated operative time,
to confirm that the inclusion/exclusion criteria were met and
the patient was eligible for participation.
Eligible patients met all of the following inclusion crite-
ria: (1) age 18 years, (2) expected surgery duration
2 hours, (3) requirement of inhalation halogenated anes-
thetic gas (i.e., sevoflurane or desflurane) as the primary
modality of anesthesia during surgery, (4) life expectancy of
>1 year (not documented as terminally ill, American Society
of Anesthesiologists classification I to III), and (5) expected
stay in the PACU of at least 1 hour following surgery.
The following criteria were used for exclusion: (1)
requirement for >23-hour hospital stay (or inpatient sur-
gery), (2) planned use of total intravenous anesthesia, (3)
inability to tolerate the use of a mask in the PACU, (4) spi-
nal or neurosurgery, (5) previous study enrollment, (6)
employment with the investigator or involvement in other
studies under the direction of the investigator or study site,
(7) pregnancy, and (8) >45 minutes between the end of
anesthetic gas administration and arrival in the PACU.
A total of 125 adult patients, scheduled for an outpatient
elective surgical procedure at Memorial Hermann
Hospital–Texas Medical Center, were enrolled in the study.
Inclusion criteria were validated, and patients were random-
ized to the traditional device group (control mask) or the
ISO-Gard mask group (study mask) postoperatively. Within
each device group were two population subsets, patients who
received sevoflurane or desflurane as the primary anes-
thetic modality.
All elements of patient care followed the institution’s
standard of practice. The patients underwent general anes-
thesia as prescribed by the attending anesthesiologist. If it
was determined perioperatively that a multimodal anesthetic
was necessary, the patient was excluded from the study. If
anesthetic gas was the primary modality utilized, then the
patient was monitored according to the study protocol.
In the operating room, standard American Society of
Anesthesiologists monitors were applied. General anesthesia
was induced by bolus administration of propofol
(1.5 to 2 mg/kg) and fentanyl (1 mcg/kg), and rocuronium
(0.6 mg/kg) was administered to provide muscle relaxation.
The patient’s lungs were ventilated via anesthesia face mask
and 100% oxygen until the patient was completely relaxed
(train of four on twitch monitor was 0). The patient’s airway
Figure 1. (a) ISO-Gard mask. (b) The MIRAN 1B SapphIRe Ambient
Air Analyzer.
44 Baylor University Medical Center Proceedings Volume 32, Number 1
was then secured either by placement of a supraglottic airway
or laryngoscopy and endotracheal intubation. Anesthesia was
maintained with either sevoflurane or desflurane inhalational
agents. The lungs were mechanically ventilated with a semi-
closed circle system to maintain an end-tidal carbon dioxide
near 35 mm Hg.
Following the operative case, patients were transported to
the PACU based on standard procedure and their arrival
time was documented. The monitoring equipment was set
up for the patient and for the PACU nurse assigned prior to
PACU arrival. Patient “hook-up”to the assigned device
attached to the wall was recorded as zero time, and recording
of WAG was initiated. The ISO-Gard mask was used as
directed by the manufacturer (oxygen flow rate of 6 L/min
and suction flow rate of 30 mm Hg). WAG concentrations
were measured with the MIRAN 1B Analyzer wand sup-
ported by a microphone stand within the patient’s breathing
zone for 60 minutes. WAG concentrations were measured
with the MIRAN 1B Analyzer with the sampling point
affixed to the caregiver’s shoulder within his or her breathing
zone for 60 minutes. Each MIRAN 1B Analyzer was cali-
brated daily prior to use and zeroed before each data collec-
tion to prevent zero drift error. Sevoflurane or desflurane
WAG environmental air concentrations were measured con-
tinuously at 30-second intervals, in parts per million resolu-
tions, using infrared spectrophotometry.
A research assistant was present throughout the duration
of the patient’s PACU stay to troubleshoot and monitor
complications with the mask or the MIRAN 1B Analyzer
(Figure 1b)or to assist the nurse, if needed. The length of
time the mask was used was observed with the “mask off
time”recorded. At the end of the 1-hour measuring period,
the equipment was collected and the patients were dis-
charged from the PACU via standard procedure.
There was no notable risk to participants of this study. In
the control arm (standard face mask), study personnel only
monitored WAG levels in the PACU under normal working
conditions. The test arm utilized the ISO-Gard mask to
deliver supplemental oxygen to patients while simultaneously
scavenging WAG. The risks associated with its use are similar
to the risks associated with using standard supplemental oxy-
gen masks. There are no known effects or dangers to patients
undergoing breathing zone analysis, and this technique has
been used safely in a previous pilot study.
6
It was the goal of this study to determine not only the
amount of WAG outgassed from the patient postoperatively
but also the amount of nurse exposure. To do this, all
PACU nurses were approached for participation because they
had the potential to care for study patients in the PACU dur-
ing the 1-hour monitoring period. During the study, the
nurses were required to wear a gas sampling line. Informed
consent was obtained from all PACU nurses to allow on-per-
son monitoring for WAG with a sampling point affixed to
their shoulder, representing the reach of their breathing
zone. Nurses assigned to patients randomized to the ISO-
Gard mask were also required to answer a survey after patient
discharge from the PACU pertaining to their experience with
the mask, and all responses were noted. The nurses worked
according to their standard of practice and were permitted to
move about freely within a 5-m radius (hose length).
Study personnel and participating nurses were oriented
to and instructed on use of the scavenging mask according to
product labeling. The research team was trained on study
execution, data collection, use of the MIRAN 1B Analyzer,
and reporting procedures specific to the study protocol. All
training was conducted under good clinical practice prior to
patient enrollment, and periodic monitoring visits were
made to ensure protocol adherence.
A sample size of 100 patients—that is, 50 patients per
group—was able to detect an effect size of 0.57 at 80%
power, 95% confidence interval, and level of significance of
P¼0.05. Patients were allocated according to a randomized
block scheme with a block size of four in a 1:1 alloca-
tion ratio.
Demographics, vital signs, laboratory variables, adverse
events/serious adverse events, and WAG levels were summar-
ized for each group. The distribution of all variables was
examined to check the validity of distribution assumptions
before any analysis, using measures of central tendency and a
visual inspection of histograms and quantile-quantile plots.
Where possible, those not meeting normality assumptions
were transformed to approximate a normal distribution, to
allow the use of parametric tests. Where data could not be
transformed, equivalent nonparametric tests were employed.
Descriptive statistics (mean ± SD for continuous variables
and frequency [percentage] for discrete variables) were sum-
marized for all variables. Continuous variables with a normal
distribution were reported as mean and SD and continuous
variables with skewed distribution were summarized as
median and interquartile ranges. Continuous variables were
analyzed by linear regression with Pvalues obtained by logis-
tic regression. Categorical variables were reported as fre-
quency and percentage using a two-sample Student’sttest
for statistical analysis with Pvalues obtained by chi-
square test.
The maximum, minimum, average, and cumulative
WAG levels in the PACU between study and control groups
were compared by two-sample ttest or Wilcoxon rank sum
test, as appropriate. The percentage of patients in which the
average WAG exposure exceeded recommended levels was
calculated and compared by chi-square test or Fisher’s exact
test, as appropriate. We also calculated and compared the
duration of the maximum (MAX) WAG levels exceeding the
recommended levels between the two groups.
For MAX-WAG measurements obtained every
30 seconds, we calculated the duration of MAX-WAG
(>2 ppm) and its proportion relative to the total collection
period. Wilcoxon’s rank sum test was applied to conduct the
comparison on the duration with MAX-WAG (>2 ppm)
and its proportion between two groups. All statistical
45Evaluation and control of WAG in the PACUJanuary 2019
analyses were performed using SAS 9.4 (SAS Institute Inc.,
Cary, NC).
RESULTS
One hundred twenty-five patients in this study received
either sevoflurane or desflurane inhaled anesthetic gas. No
adverse events related to the ISO-Gard mask were noted.
Equipment failure led to the exclusion of 17 cases from the
data analyses. Of the 108 included cases, women made up
64% of the participants (Table 1).
Twenty-four PACU nurses participated in this study over
the course of 4 months. They were surveyed at the conclu-
sion of each case, with most reporting “good”to “excellent”
integration of the device into standard procedures with min-
imal impedance to workflow.
There was no significant difference in randomization
between study and control groups. Fifty-six patients made up
the traditional mask group (group 0), with 57.1% in the des-
flurane subgroup and 42.9% in the sevoflurane group. Fifty-
two patients were in the ISO-Gard group (group 1), with
59.6% in the desflurane subgroup and 40.4% in the sevo-
flurane group. No significant differences were observed in
duration of data collection in patients who received either
inhaled gas in either mask group.
As shown in Table 2, within the patient’s breathing zone,
the median duration of MAX-WAG (>2 ppm) was
19.5 minutes in group 0 and 13.5 minutes in group 1
(P¼0.02). The median proportion of MAX-WAG
(>2 ppm), which refers to the percentage of MAX-WAG in
relation to the total collection period, within the patient’s
breathing zone was 32.2% in group 0 and 22.4% in group 1
(P¼0.03). The duration and proportion values remained
significant for the subgroup of patients receiving anesthesia
with desflurane (P¼0.03 and 0.04, respectively) but not for
the subgroup of patients receiving anesthesia with sevoflur-
ane (P¼0.27 and 0.33, respectively) (Table 2).
Within the nurse’s breathing zone (Table 3), the median
duration of MAX-WAG (>2 ppm) was 3.0 minutes in group
0 and 1.0 minutes in group 1 (P<0.01). The median pro-
portion of MAX-WAG (>2 ppm) was 4.7% in group 0 and
2.0% in group 1 (P<0.01). As with the patient’s breathing
zone, the duration and proportion values remained signifi-
cant for the subgroup of patients receiving anesthesia with
desflurane but not for those receiving anesthesia with
sevoflurane.
Table 2. Maximum waste anesthetic gas within the patient’s breathing zone
Variable
Randomization group
PvalueTraditional mask (control) ISO-Gard mask
All patients (n) 56 52
Collection duration (min), mean ± SD 58.7 ± 8.1 56.7 ± 10.2 0.26
Duration of MAX-WAG >2 ppm (min), median (Q1, Q3) 19.5 (12.0, 37.6) 13.5 (3.2, 24.0) 0.02
Proportion of MAX-WAG >2 ppm during collection (%), median (Q1, Q3) 32.2%(20.4, 61.1) 22.4%(6.4, 40.4) 0.03
Anesthesia with desflurane (n) 32 31
Collection duration (min), mean ± SD 59.6 ± 7.6 58.4 ± 9.0 0.57
Duration of MAX-WAG >2 ppm (min), median (Q1, Q3) 21.0 (13.5, 43.2) 14.7 (2.5, 26.3) 0.03
Proportion of MAX-WAG >2 ppm during collection (%), median (Q1, Q3) 33.7%(22.8, 75.6) 23.6%(4.2, 41.0) 0.04
Anesthesia with sevoflurane (n) 24 21
Collection duration (min), mean ± SD 57.4 ± 8.7 54.1 ± 11.6 0.28
Duration of MAX-WAG >2 ppm (min), median (Q1, Q3) 19.0 (11.0, 23.1) 13.5 (3.5, 21.0) 0.27
Proportion of MAX-WAG >2 ppm during collection (%), median (Q1, Q3) 29.7%(19.8, 47.2) 21.2%(6.5, 39.8) 0.33
MAX-WAG indicates maximum waste anesthetic gas; Q1, first quartile; Q3, third quartile.
Pvalues obtained by ttest; other Pvalues were obtained by Wilcoxon’s rank sum test.
Table 1. Study population
All cases Included cases
Total Female Male Total Female Male
Total (%) 125 79 (63.2%) 46 (36.8%) 108 69 (63.9%) 39 (36.1%)
Control cases 64 44 20 56 41 15
Desflurane 35 30 5 32 27 5
Sevoflurane 29 14 15 24 14 10
Iso-Gard cases 61 35 26 52 28 24
Desflurane 33 21 12 31 19 12
Sevoflurane 28 14 14 21 9 12
46 Baylor University Medical Center Proceedings Volume 32, Number 1
DISCUSSION
Patient care during surgery and in the PACU requires
medical staff to perform to their best professional capacity.
Though it is known that work efficiency may decrease as a
result of fatigue, scientific evidence has demonstrated that
breathing WAG contributes to fatigue and work impair-
ment.
7
In addition, animal studies have shown that exposure
to high levels of nitrous oxide and halogenated gases can
cause cellular, mutagenic, carcinogenic, and teratogenic
effects. Exposed groups have a reported higher incidence of
infertility, spontaneous abortion, congenital abnormalities,
premature births, cancer, and renal and hepatic disease.
8
The operating room has been classically linked to expos-
ure to high concentrations of WAG, but little is known
about potential hazards associated with continuous trace
exposure in the PACU.
9
Traditionally, the PACU is not con-
sidered an area with increased risk of exposure to WAG,
which is why scavenging devices are not routinely used.
However, recent studies indicate that the possibility of
exceeding NIOSH-recommended guidelines in the
PACU exists.
This study was based on a previous pilot study on the
exposure of nurses in the PACU to WAG, which found that
PACU nurses were potentially exposed to higher than recom-
mended levels of WAG (<2 ppm).
6
Similarly, McGlothin
et al found significantly higher than recommended concen-
trations of WAG within the patient’s breathing zone during
the first 15 minutes of the PACU stay.
10
They also found
that PACU nurses were exposed to significantly higher than
recommended concentrations of WAG within their breath-
ing zone and within 6 feet of patients, where concentrations
of nitrous oxide were up to three times higher than that of
controls who were using scavenging devices.
10
Upon PACU arrival, measurable amounts of WAG will
still be exhaled by patients because ventilation is the primary
method of elimination. During this time, the most intensive
bedside nursing is required, thus constituting an underesti-
mated period of occupational risk for PACU nurses.
11
Another study concluded that peak WAG levels were
detected 1 hour after patient arrival to the PACU, contrary
to the initial hypothesis in which investigators expected peak
WAG levels to occur at admission.
12
The location where the
airway device is removed should also be considered; patients
whose device is removed in the PACU versus the operating
room yield higher initial concentrations of WAG than those
who arrive to the PACU without a device.
13
In our study, all
patients were extubated prior to PACU arrival.
To address this issue, our study aimed to verify whether
NIOSH guidelines regarding WAG exposure were being met
and assess a possible solution. Our data suggest that patients
using the ISO-Gard mask had a statistically significant
shorter duration and lower median proportion of exposure to
MAX-WAG (P¼0.02 and 0.03, respectively). The nurses
also had a similar outcome (P<0.01 for both) (Figure 2).
This indicates the efficacy of the ISO-Gard mask in scaveng-
ing WAG and reducing exposure to patients and nurses in
the PACU.
Subgroup analysis of patient and nurse breathing zones
suggested a statistically significant difference in the duration
and median proportion of MAX-WAG (>2 ppm) between
the two groups and the desflurane subgroup. No significant
differences were noted in the group that received sevoflurane.
Table 3. Maximum waste anesthetic gas within the nurse’s breathing zone
Variable
Randomization group
PvalueTraditional mask (control) ISO-Gard mask
All patients (n) 56 52
Collection duration (min), mean ± SD 60.6 ± 20.6 56.9 ± 9.7 0.24
Duration of MAX-WAG >2 ppm (min), median (Q1, Q3) 3.0 (1.5, 6.5) 1.0 (0, 3.0) <0.01
Proportion of MAX-WAG >2 ppm during collection (%), median (Q1, Q3) 4.7%(2.4, 9.8) 2.0%(0, 5.7) <0.01
Anesthesia with desflurane (n) 32 31
Collection duration (min), mean ± SD 64.0 ± 25.9 58.1 ± 9.1 0.24
Duration of MAX-WAG >2 ppm (min), median (Q1, Q3) 3.8 (1.5, 9.5) 1.0 (0, 3.0) <0.01
Proportion of MAX-WAG >2 ppm during collection (%), median (Q1, Q3) 5.9%(2.6, 15.0) 1.5%(0, 5.7) <0.01
Anesthesia with sevoflurane (n) 24 21
Collection duration (min), mean ± SD 56.0 ± 8.7 55.1 ± 10.6 0.76
Duration of MAX-WAG >2 ppm (min), median (Q1, Q3) 2.0 (1.0, 5.4) 1.5 (0.5, 3.0) 0.21
Proportion of MAX-WAG >2 ppm during collection (%), median (Q1, Q3) 4.0%(1.7, 8.0) 2.6%(1.0, 5.8) 0.24
MAX-WAG indicates maximum waste anesthetic gas; Q1, first quartile; Q3, third quartile.
Pvalues obtained by ttest; other Pvalues were obtained by Wilcoxon’s rank sum test.
47Evaluation and control of WAG in the PACUJanuary 2019
As a side note, the sample size of patients who received sevo-
flurane was smaller than that for desflurane (43/108 vs
65/108), which may have influenced this finding.
Though it is clear that elevated levels of WAG occur in
the PACU nurse breathing zone, our study was not designed
to obtain the long-term outcomes of participating nurses. As
such, the precise consequences of long-term exposure to trace
WAG levels in the PACU setting remain undetermined.
Additionally, we did not measure the cumulative doses of
WAG for each PACU nurse; the investigators considered
doing so, but available measuring technology was expected to
have resulted in inaccurate readings.
Another limitation is that precise dosing of volatile anes-
thetics was not recorded. Dosing was practitioner dependent,
and more than 40 different anesthesiologists administered
volatile anesthetics to study patients. In general, overall
exhaled levels of sevoflurane were lower than those of desflur-
ane, though this would be anticipated given the higher con-
centration of desflurane needed to achieve appropriate
minimum alveolar concentration levels. Hiller et al provide
further discussion on the pharmacokinetics of volatile
anesthetics.
11
Studies have demonstrated that to maximize effectiveness
in controlling WAG exposure, practices such as appropriate
mask size selection and adjustment, minimal talking, mouth
breathing by the patient, and use of a vacuum scavenging
system must be implemented.
14
We strongly encourage
investigators and government agencies to work in conjunc-
tion to update existing protocols related to occupational
WAG exposure and include the PACU setting as a potential
hazard location in which standard scavenging measurements
should be practiced.
In conclusion, patients continue to expel WAG at con-
centrations >2 ppm during the 1-hour postoperative period,
with PACU nurses intermittently being exposed to WAG at
concentrations >2 ppm during this time frame. The ISO-
Gard mask effectively reduces the amount of WAG detected
in the immediate 1-hour postoperative period in both the
patient and nurse breathing zones. The long-term
consequence of this exposure to PACU nursing staff remains
undetermined.
ACKNOWLEDGMENTS
The authors thank the PACU nursing team at Memorial Hermann
Hospital–Texas Medical Center, whose cooperation and participation
made this project possible.
FUNDING
The authors acknowledge work attributed to and financial support
provided by Teleflex, Incorporated (Raleigh, NC), and The
University of Texas Medical School at Houston, Department of
Anesthesiology. Dr. Cai’s research was supported by the National
Institutes of Health’s Clinical and Translational Science Award Grant
(UL1 TR000371).
ORCID
Tariq A. Syed http://orcid.org/0000-0001-7351-5572
Tyrone Burnett http://orcid.org/0000-0002-1169-770X
Stephanie H. Ahn http://orcid.org/0000-0002-8280-6707
Chunyan Cai http://orcid.org/0000-0002-7213-621X
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49Evaluation and control of WAG in the PACUJanuary 2019
