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Analysis of Cricoid Pressure Forceand Technique Among Anesthesiologists,Nurse Anesthetists, and Registered Nurses
Melissa Lefave, DNP, APRN, CRNA, Brad Harrell, DNP, APRN, ACNP-BC, CCRN,
Molly Wright, DNP, APRN, CRNA
Purpose: The purpose of this project was to assess the ability of anesthesi-
Melissa Lefave,
Nurse Anesthesia T
versity, Jackson, T
CCRN, Clinical As
Loewenberg Colle
Wright, DNP, APR
thesia Track in the
son, TN.
Conflict of intere
Address corresp
Dr., Brownsville, T
� 2016 by Ame
1089-9472/$36.
http://dx.doi.org
Journal of PeriAnesth
ologists, nurse anesthetists, and registered nurses to correctly identify
anatomic landmarks of cricoid pressure and apply the correct amount
of force.Design: The project included an educational intervention with one group
pretest-post-test design.Methods: Participants demonstrated cricoid pressure on a laryngotra-
cheal model. After an educational intervention video, participants were
asked to repeat cricoid pressure on the model.Findings: Participants with a nurse anesthesia background applied
more appropriate force pretest than other participants; however, post-
test results, while improved, showed no significant difference among pro-
viders. Participant identification of the correct anatomy of the cricoid
cartilage and application of correct force were significantly improved af-
ter education.Conclusion: This study revealed that participants lacked prior knowledge
of correct cricoid anatomyand pressure as well as the ability to apply cor-
rect force to the laryngotracheal model before an educational interven-
tion. The intervention used in this study proved successful in educating
health care providers.
Key Words: cricoid pressure, nurse, anesthesiologist, nurse anesthetist,
Sellick’s maneuver, cricoid anatomy.
� 2016 by American Society of PeriAnesthesia Nurses
CRICOID PRESSURE, OFTEN termed ‘‘Sellick’smaneuver,’’ is used for the prevention of regurgi-
tation of gastric contents during induction of
DNP, APRN, CRNA, Associate Professor,
rack in the School of Nursing Union Uni-
N; Brad Harrell, DNP, APRN, ACNP-BC,
sociate Professor, University of Memphis
ge of Nursing, Memphis, TN; and Molly
N, CRNA, Chair & Professor, Nurse Anes-
School of Nursing Union University, Jack-
st: None to report.
ondence to Melissa Lefave, 130 Woodland
N 38012; e-mail address: [email protected].
rican Society of PeriAnesthesia Nurses
00
/10.1016/j.jopan.2014.09.007
esia Nursing, Vol 31, No 3 (June), 2016: pp 237-244
anesthesia or during positive-pressure ventilation.This technique was described by Sellick1(p405) in
1961 as ‘‘backward pressure of the cricoid carti-
lage against the bodies of the cervical vertebrae.’’
Sellick, however, was the not the first to consider
the advantages of such a maneuver. William
Cullen2(p16) in 1774 wrote, ‘‘whether the blowing
in is done by a person’s mouth, or by bellows, Dr.
Munroe observes, that the air is ready to pass bythe gullet into the stomach; but that this may be
prevented, by pressing the lower part of the larynx
backwards upon the gullet.’’ In 1776, Hunter3(p419)
described how the larynx could be gently pressed
against the esophagus and spine while ‘‘blowing
air into the lungs’’ to ‘‘prevent the stomach and in-
testines being too much distended by the air.’’
237
238 LEFAVE, HARRELL, AND WRIGHT
Despite sporadic reports that cricoid pressure may
not be as effective as once thought, the ‘‘Sellickma-
neuver’’ remains an accepted practice that is used
worldwide.4-8 One author9(p94) even suggests that
the omission of cricoid pressure in patients withknown or suspected risk factors of aspiration
would be unethical ‘‘until there is conclusive evi-
dence to suggest otherwise.’’
Patients at Risk for Pulmonary Aspiration
Induction of anesthesia may cause gastroesopha-
geal contents to enter the pharynx and tracheal-
bronchial passages, leading to a life-threatening
aspiration.10 Although aspiration of gastric con-
tents accounts for only 3.5% of all anesthesia
malpractice suits, it is a major source of anesthesia
morbidity.11 When deciding on candidates forcricoid pressure, it is prudent to identify those at
a greater risk of regurgitation and pulmonary aspi-
ration because of pathology or physiology
(Table 1). Such persons have pre-existing factors
that may lead to the presence of gastric contents.
Table 1. Patients at Increased Risk ofRegurgitation and Pulmonary Aspiration1,2
Severe trauma
Parturient . 14-wk gestation
Hiatal hernia
Gastroesophageal reflux disease
Diabetes mellitus
Gastroparesis
Extremes of age
Increased intra-abdominal pressure
Obesity
Abdominal ascites
Gastrointestinal obstruction
Ileus
Difficult intubation
Patient who does not meet NPO criteria for anesthesia
, 8 h since heavy meal
, 6 h since light meal
, 2 h since clear liquid intake
Neurologic factors
Glasgow Coma Scale , 8
Parkinson disease
Multiple sclerosis
Bulbar palsy
Myotonia dystrophica
Cerebrovascular accidents
Increased intracranial pressure
Narcotic administration
NPO, nothing by mouth.
Undetermined gastric volume, gastrointestinal
dysfunction, and altered lower esophageal
sphincter tone are among indications for the utili-
zation of cricoid pressure during rapid sequence in-
duction of anesthesia or during positive-pressureventilation.12
Anatomy
The cricoid cartilage is a complete ring of hyaline
cartilage just inferior to the thyroid cartilage (ie,
Adam’s apple).13 Identification of correct cricoid
cartilage anatomy is crucial to the success ofcricoid pressure and prevention of pulmonary
aspiration. The thyroid prominence should be
visualized on the front of the neck. It is the most
prominent protuberance midline. During palpa-
tion of the thyroid prominence, movement of the
finger caudally (toward the patient’s feet) will iden-
tify a drop into the cricothyroid notch or mem-
brane. The next horizontal structure is thecricoid cartilage.14
Although the efficacy of cricoid pressure has been
debated, Rice et al15 confirmed Sellick’s 1961 pro-
posal that ‘‘cricoid pressure compresses the
conduit between the stomach and the pharynx
as intended.’’ However, the authors further empha-
size that cricoid pressure does not occlude theesophagus, as the esophagus does not lie behind
the cricoid cartilage. Rice et al15 state that cricoid
pressure compresses the anterioposterior diam-
eter of the hypopharynx.
Force
The degree of cricoid pressure force is an impor-tant element to consider. Too little force leaves
the airway susceptible to the possibility of regurgi-
tation and ensuing aspiration. Excessive force has
been documented to worsen the laryngeal view,
causing difficulty with laryngoscopy and even pul-
monary ventilation.16 Furthermore, rupture of the
esophagus has been reported after active vomiting
during the application of cricoid pressure.5
The optimal force of application of cricoid pressure
has been debated before it came into common use.
Sellick merely suggested that ‘‘firm’’ pressure be
applied without obstructing the patient’s airway.1
Wraight et al17 recommended the initial force of
44 Newtons (N) from a study of 24 elective
Figure 1. Life-sized adult airway model on an
EBSA-20 infant scale. This figure is available in color
online at www.jopan.org.
CRICOID PRESSURE FORCE AND TECHNIQUE 239
anesthesia cases in 1983. In 1999, Vanner and
Asai18 recommended 10 N for the conscious pa-
tient increasing to 30 N once unconscious. A gen-
eral consensus of 30 to 40 N is now accepted to
generate adequate pressure to occlude the esoph-agus and prevent gastroesophageal regurgita-
tion.9,19
Technique
A single-handed or double-handed technique can
be used for cricoid pressure. Furthermore, two
or three fingers can be used to exert pressure.When using two fingers, the provider places the
cricoid cartilage between the first and second fin-
gers applying downward force. The three-finger
technique stabilizes the cricoid cartilage between
the thumb and third finger with the index finger
applying force.
Purpose
Cognitive and clinical application deficits exist
among health care providers in the performance
of cricoid pressure. Improper and inconsistent
application may increase the patient’s risk forregurgitation and subsequent aspiration of gastric
contents. The clinical implications associated
with improperly applied cricoid pressure warrant
evaluation of the cognitive knowledge and applica-
tion technique of providers. The purpose of this
project was to assess the ability of perioperative
hospital personnel (anesthesiologists, nurse anes-
thetists, and registered nurses) to correctly iden-tify appropriate anatomic landmarks of cricoid
pressure and apply the correct amount of force.
The researcher aimed to alert health care providers
of incorrect practice and to evaluate further educa-
tional needs among various groups of providers.
Furthermore, post-test data allowed for evaluation
of the educational instrument.
Design
This study was an educational intervention with a
group pretest–post-test design. Using nonprob-
ability purposive sampling, study participantsincluded anesthesiologists, nurse anesthetists,
preoperative registered nurses, intraoperative
registered nurses, postoperative registered nurses,
and registered nursesworking in the intensive care
unit at a 635-bed tertiary care hospital. Periopera-
tive and intensive care registered nurses were
included because oftentimes anesthesia providers
need their help in applying cricoid pressure during
induction of anesthesia, emergency intubation, or
during bag-mask ventilation. Exclusion criteriaincluded participants unable to speak English.
Sample size was limited to consenting participants
actively working at the hospital during the study
dates.
The institutional review board of an affiliated uni-
versity approved the study protocol and required
the inclusion of a human subjects consent form.Study approval was also obtained from the hospi-
tal’s institutional review board. Permissions were
also obtained from the hospital’s chief nursing offi-
cer, nursing unit directors, and nurse anesthesia
administrators.
Instrument
The use of a plastic laryngotracheal model placed
upon an infant scale with a digital display was uti-
lized for data collection (Figure 1). A towel covered
the digital display during the intervention to pre-
vent the participant from viewing their forceapplied to the model before and after the test. The
model was a life-sized upper airway with clearly
defined airway anatomy including cricoid cartilage.
An electronic baby scale, EBSA-20, infant scale with
a digital display of 0 to 20 kg, with 0.01 kg incre-
ments, was used.
This instrument has been used and validated byother researchers. Herman, et al.20(p862) described
it as ‘‘an effective and easy model for instructing,
practicing, and refreshing the recommended force
240 LEFAVE, HARRELL, AND WRIGHT
to apply andachieveesophageal occlusionusing the
Sellick maneuver’’ allowing ‘‘one to better obtain a
morequantifiable and reproduciblemeansof assess-
ing effort.’’ Beavers et al9 used this toolwith success.
May and Trethewy21(p208) used a less descriptivelaryngeal model mounted on a self-calibrating digi-
tal postage scale stating, ‘‘the use of such devices
for this purpose has been validated.’’
Methods
Participants were presented an informed consent
to participate in the study. If needed, explanation
Figure 2. Data collection
was provided by the investigator, and questions
were answered. A string of alphanumeric identi-
fiers were used to maintain participant anonymity.
After verbal consent was obtained, the partici-
pants were asked to complete an initial demo-graphic data form delivered via electronic survey
(Figure 2). This instrument was used to collect
baseline demographics including gender, hand
dominance, occupation, years of application of
cricoid pressure, cricoid pressure training within
the previous 12 months, and knowledge of the
amount of cricoid force required during cricoid
pressure.
form. ID, identification.
CRICOID PRESSURE FORCE AND TECHNIQUE 241
The participant was then asked to apply pressure
to the laryngotracheal model pretest with the dig-
ital display covered by the towel. The investigator
assessed and documented the anatomic applica-
tion, technique, hand used, and force applied tothe model. Force was measured by instructing
the participant to alert the investigator when
they applied adequate force to the model. Next,
an educational intervention in the form of a 2-min-
ute video via laptop was given to the participants,
allowing two times to practice cricoid pressure on
the laryngotracheal model during the intervention
while viewing the digital display of force on thescale. The video was published by the researcher,
Figure 3. Postintervention educational handout. This fi
describing the indications, anatomy, technique,
force, and contraindications of cricoid pressure.
After the intervention, participants were asked to
reapply cricoid pressure on the laryngotrachealmodel with the digital display of force covered.
Again, the investigator assessed and documented
the anatomic application, technique, hand used,
and force applied to the model. On completion
of the study, participants were notified of their pre-
test and post-test results and provided an educa-
tional handout (Figure 3) describing the
significance, indications, and technique of cricoidpressure.
gure is available in color online at www.jopan.org.
242 LEFAVE, HARRELL, AND WRIGHT
Statistical Analysis
Descriptive statistics were calculated for the three
continuous variables of force pretest, force post-test, and years of cricoid pressure application.
Descriptive statistics for discrete variables
including yes and no questions were reviewed.
Wilcoxon signed rank test determined if there
were significant differences between the identifi-
cation of cricoid anatomy pretest and post-test.
A Kruskal-Wallis test was used to determine if pre-
test and post-test differences were significantlydifferent among the various participant occupa-
tions. Pearson correlation analysis determined if
the pretest and post-test forces were related to
the participant’s years of cricoid pressure applica-
tion. Nominal by interval cross tabulation of
continuous data (pretest and post-test force) and
discrete data (nominal yes or no data) determined
whether pretest and post-test forces were depen-dent on gender or hand dominance.
Findings
A total of 61 participants were involved in thisstudy including two anesthesiologists, 17 nurse
anesthetists, 7 preoperative registered nurses, 15
intraoperative registered nurses, 10 postoperative
registered nurses, and 10 intensive care nurses
(Figure 4). The recommended cricoid pressure
was 3 to 4 kg (30 to 40 N). Descriptive analysis
revealed a mean pretest force of 2.47 kg, mean
post-test force of 3.78 kg, and amean of 10.66 yearsof experience applying cricoid pressure. Seventy-
Figure 4. Participant demographic distribution according
able in color online at www.jopan.org.
seven percent of participants were female and
23% male. Hand dominance analysis revealed
88.5% of participants were right handed, and
11.5% were left handed. Only 14 of the 61 partici-
pants gave responses for the data collectionquestion regarding their pre-existing knowledge
of the recommended force of cricoid pressure.
Of the 14, only 2 participants answered correctly
within the range of 3 to 4 kg (30 to 40 N).
Twelve participants (19.7%) identified correct
cricoid cartilage pretest, whereas all participants
correctly identified the anatomy post-test. TheWilcoxon signed rank test revealed that there
was a significant difference (Z 5 27.000,
P 5 .000) between the participants’ identification
of correct cricoid cartilage post-test versus pre-
test (Figure 5).
The Kruskal-Wallis test determined that there was
a significant difference (P 5 .010) between theoccupation of the participant and the force
applied before the test. None of the anesthesiolo-
gists, 10 nurse anesthetists, 1 preoperative nurse,
2 intraoperative nurses, 2 postoperative nurses,
and 1 intensive care nurse applied correct cricoid
pressure force pretest. However, there was no sig-
nificant difference (P5 .111) between the occupa-
tion of the participant and the force applied afterthe test. One anesthesiologist, 11 nurse anesthe-
tists, 4 preoperative nurses, 11 intraoperative
nurses, 6 postoperative nurses, and 9 intensive
care nurses applied correct cricoid pressure force
post-test (Figure 6). Pearson correlation analysis
to occupation. RN, registered nurse. This figure is avail-
Figure 5. Correct identification of cricoid anatomy
in percentage by participants. Preop, preoperative;
RN, registered nurse; Intraop, intraoperative; Postop,
postoperative; ICU, intensive care unit. This figure is
available in color online at www.jopan.org.
CRICOID PRESSURE FORCE AND TECHNIQUE 243
determined that the pretest (r 5 0.214, P 5 .098)
and post-test (r 5 20.074, P 5 .573) forces were
not related to the participant’s years of cricoid
pressure application.
Nominal by interval cross tabulation determined
pretest (Eta 5 .142) and post-test (Eta 5 0.026)forces were not dependent on gender. Likewise,
nominal by interval cross tabulation determined
pretest (Eta 5 0.080) and post-test (Eta 5 0.058)
forces were not dependent on hand dominance.
Conclusions
The clinical importance of cricoid pressure in the
prevention of regurgitation and aspiration of
Figure 6. Mean force applied in kilograms pretest
and post-test by participants. Three kilogram to 4 kg
is the correct amount of cricoid pressure required.
Preop, preoperative; RN, registered nurse; Intraop,
intraoperative; Postop, postoperative; ICU, intensive
care unit. This figure is available in color online at
www.jopan.org.
gastric contents has been established throughout
history. It is prudent to ensure that the medical
community practices the techniquewith accuracy.
This study revealed that participants lacked prior
knowledge of correct cricoid anatomy and pres-sure as well as the ability to apply correct force
to the laryngotracheal model before an educa-
tional intervention. The intervention used in this
study proved successful in educating medical pro-
viders. A greater percentage of participants were
able to successfully apply 3 kg to 4 kg of force to
the model post-test, and 100% of participants iden-
tified correct cricoid anatomy post-test.Sellick1(p405) said ‘‘the nurse or midwife accompa-
nying the patient can be shown in a few seconds
how to do it [apply cricoid pressure].’’ This was
accomplished in this study within 2 minutes using
the educational video.
Specifically, it is important to note that as one
intraoperative registered nurse applied force tothe model, no force was detected on the digital
display by the investigator. On checking with
the nurse if she was applying pressure, she
stated that she was indeed applying pressure.
She further stated that she always squeezes the
throat and would never push down because
that would obstruct the view of the person intu-
bating. This nurse had been applying cricoidpressure incorrectly for 38 years. Fortunately,
she applied a post-test pressure of 2.98 kg.
This single participant’s experience alone ver-
ifies the significance of education and training
of cricoid pressure.
Acknowledgments
The authors thank Linn M. Stranak, DA, at Union University for
his statistical help and expertise.
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