Modified mallampati classification in determining the success of unsedated transesophageal echocardiography procedure in patients with heart disease: simple but efficient
Khongkaew et al. Cardiovascular Ultrasound
Modified mallampati classification in determining the success of unsedated transesophageal echocardiography procedure in patients with heart disease: simple but efficient
Jureerat Khongkaew 0
Tharrittawadha Potat 0
Phatchara Thammawirat 0
0 Queen Sirikit Heart Center of the Northeast, Faculty of Medicine, Khon Kaen University , Khon Kaen , Thailand
Background: The transesophageal echocardiograhpy (TEE) has been studied worldwide. However, identifying additional factors on top of operator's experience and patient's cooperation which could influence the success of the procedure in unsedated patients with heart disease is not well documented. Methods: Under the cross-sectional descriptive design, 85 target patients were fulfilling the criteria: being Thai national at the age of at least 20-year-old, being performed TEE by the study participant's cardiologists, being able to communicate verbally. Seven outcomes were recorded, including gag reflex, insertion attempt, insertion time, vital signs (heart rate, oxygen saturation and mean arterial blood pressure), visible blood on TEE probe tip, and oropharyngeal pain at 1 h and 24-h. Results: There were 85 eligible patients during June 2012 to June 2013. The major participants were male (46, 54 %) and the mean age was 51.2 ± 12.5 years. The MMC class III was mostly found (33, 38.80 %). TEE probe insertion time and gag reflex were indicated statistical significance (P < 0.05). Linear regression revealed that MMC class III (b 3.718; SD ± 1.077; P = 0.001) and class IV (b 5.15; SD ± 1.286; P = 0.000) were statistically associated with TEE probe insertion time, whereas MMC class II was no statistically significant (b 2.348; SD ± 1.405; P = 0.099) according to constant value in MMC class I (5.318 s). Similarly, logistic regression indicated that the patients with high grade MMC were more likely to have gagging than the low grade MMC patients (MMC 2 OR 0.567, 95 % CI 0.09-3.42, P = 0.536; MMC 3 OR 5.231, 95 % CI 1.55-17.67, P = 0.008; MMC 4 OR 3.4, 95 % CI 0.84-13.76, P = 0.086). Conclusions: Modified Mallampati Classification is one of determining factors in the success of unsedated TEE procedure in patients with heart disease, especially for assessment of gagging and successful TEE probe insertion time.
Modified Mallampati Classification; Unsedated transesophageal echocardiography; Heart disease patient
In the non-invasive cardiac diagnostic settings
worldwide, a transesophageal echocardiography (TEE) can be
performed with or without conscious sedation.
According to the guidelines for performing a TEE, the
procedure is well tolerated by an unsedated patient who is
adequately given oral anaesthesia . Comparing with a
sedated TEE, the unsedated patients show a lower
incidence of cardiopulmonary complications and also
receive more in benefit in terms of recovery time and
medical care cost [1, 2]. However, performing a TEE
without sedation requires a well cooperative patient
since the procedure can easily injure organs, including
lips, teeth, oropharynx, larynx, esophagus and stomach
[3, 4]. In addition, the patients who show gagging during
the procedure tend to have more oropharygeal injury
than the absent gagging group [5, 6].
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As gagging is a significant obstacle to succeed in
performing an unsedated TEE, oropharynx assessment
should be considered as an important process. However,
previous studies mention that only operator’s experience
and patient’s cooperation are the two influencing factors
[1, 4]. In the field of gastrointestology, Huang, et al.
compare the tolerance in esophagogastroduodenoscopy
(EGD) among the patients based on Modified
Mallampati Classification (MMC) . The result clearly shows
that the patients with MMC class III and class IV mostly
present gagging during the procedure which leads the
patient to be intolerant and be given sedation. Also, in
the field of anaesthesiology, the MMC has been accepted
as one of the factors affecting a successful endotracheal
tube intubation [7, 8, 9]. Focusing on the field of
cardiology, there is a lack of data supporting the correlation
between MMC and the TEE outcomes. Even though
TEE probe insertion is technically easier than
endotracheal tube intubation, some complications can occur
since the long probe has to be passed oropharynx before
being inserted into the esophagus. From this point of
view, our present study aims to identify additional factors
on top of operator experience and patient co-operation
which can influence the success of a TEE procedure in
unsedated patients with heart disease.
This study was approved by the Human Research Ethics
Committee of Khon Kaen University, Thailand. The
patients who were considered for the study’s inclusion
would meet specific criteria, including being a Thai
national at the age of 20-year-old or more, being
performed the TEE by the participant’s cardiologist, being
able to communicate verbally in Thai language, and
willing to have the unsedated TEE as well as willing to be
the study’s participant. The excluded patients were those
younger than 20-year-old, unwilling to have the
unsedated TEE and to participate in the study, incomplete
informed consent form, unable to communicate verbally
in Thai language, having a history of dysphagia or
bleeding disorder, undergoing oropharyngeal surgery, unable
to be assessed MMC, and being given sedation before or
during the procedure.
The data was collected using the specific form, consisted
of three significant parts: demographic data, factors
involving TEE procedure, and the seven TEE outcomes
(insertion attempt, successful insertion time, gag reflex
during insertion, vital signs’ change, oropharyngeal pain
at 1-h and 24-h, and visible blood on probe tip). Initially,
the informed consent form must be completed.
Throughout the procedure, neither the cardiologists
together with the two collecting data nurses nor the
patient themselves knew the patient’s MMC class, except
the two well-trained MMC assessment nurse who
graded patients’ MMC class using the MMC chart as
shown in Fig. 1.
According to our hospital TEE preparation, the
patient would be orally anaesthetized receiving
lidocaine (Astra Zeneca) both 10 % spray and 2 % jelly.
With a total safe dosage of less than 400 mg ,
150 mg of lidocaine jelly was orally given to the
patient twice; the second dose was administered five
minutes following the first. The patient would be
then evaluated the gag reflex and would be given 2
more puffs (20 mg) of lidocaine spray if gagging was
presented. When the oropharyngeal preparation was
completed, the patient was placed in left lateral
Before TEE probe insertion, a bite guard was already
put in place. While the patient was lying in the specific
position under the safety setting, the operator gently
entered a lubricated TEE probe (model GE 6Tc) into the
patient oral cavity. Once the probe being passed through
the patient’ mouth until being placed into the esophagus,
presented gagging, vital signs, successful TEE probe
insertion time and attempt were noted in agreement of the
two collecting data nurses.
After the procedure had been completed, the
transducer was slowly pulled out of the patient mouth and
was placed on a white towel in order to evaluate blood
on the transducer tip. The patient vital signs were
continuously monitored for 30 min. Oropharyngeal pain at
1 h and 24-h were assessed by means of a phone call
asking the patient to state a 0–10 oropharyngeal pain
score, adapted from visual analog scale (VAS) as shown
in Fig. 2.
Definition of terms
1. Patient’s cooperation refers to a willingness to have
unsedated TEE procedure which is evaluated by
observation of the patient’s compliance with topical
anaesthesic agent given and facial expression. The
criteria are below.
1.1Excellent cooperation is rated for the patient who
shows smiling face and truly willingness to be
anaesthetized for the unsedated TEE procedure.
1.2Good cooperation is described as the patient
presents with neutral face and actions.
1.3Poor cooperation refers to the patient showing
unhappy face and being difficult to give topical
2. Insertion attempt means the number of attempt to
insert the TEE probe into the patient’s esophagus
Fig. 1 Modified Mallampati Classification
3. Successful probe insertion time refers to the specific
time when the TEE probe can be in place.
4. Gag reflex during insertion refers to a gagging which
is stimulated by the touching of the TEE probe on
the patient’s oropharynx before being placed into the
5. Vital signs’ change is noted if there is a decrease of
oxygen saturation less than 90 % or a 20 % change of
either heart rate (HR) or mean arterial pressure (MAP).
The raw data was analyzed using SPSS for windows
version 17.0. The continuous data were presented as mean
± standard deviation (SD) while all categorical data were
shown as absolute number and percentage (%). The
difference and correlation between the MMC and seven
related variables (insertion attempt, successful probe
insertion time, gag reflex, vital signs’ change, visible
blood on probe tip, and oropharyngeal pain score at 1-h
and at 24- h) were analyzed using one-way ANOVA and
simple linear regression analysis for continuous data,
whereas chi square and logistic regression analysis were
used for analyzing categorical variables. P value < 0.05
was considered as statistic significant.
Patient’s demographic characteristics
Throughout a year (June 2012-June 2013), a total of 147
heart disease patients underwent the TEE procedure at
Queen Sirikit Heart Center of the Northeast, Faculty of
Medicine, Khon Kaen University. There were 86 patients
who met the study inclusion criteria. Only one case was
excluded due to left jaw pain which affected mouth
opening. Out of 85 eligible patients, most of them were
Fig. 2 Oropharyngeal pain scale, adapted from visual analog scale (VAS)
male (46, 54 %). The mean age and BMI were 51.2 ±
12.48 and 23.95 ± 4.72, respectively. Sixty-one patients
(71.8 %) had no experience with the TEE, but showed
good cooperation (59, 64.40 %). Also, nearly half of them
took anticoagulant medications (42, 49.40 %). MMC
class III was the most presented class (33, 38.80 %) and
was mostly found in women (20, 60.6 %). All parameters
are shown in Table 1.
Comparison of TEE outcomes among the patients based
Out of the seven outcomes, only the gag reflex and the
successful TEE probe insertion time indicated statistical
significance (P = 0.005). Among the four groups, the patient with
MMC class III (20, 60.6 %) and MMC IV (8, 50.0 %) were
the first two group which mostly presented gagging while
the less presented gagging were the patients with MMC
class I (5, 22.7 %) and class II (2, 14.3 %). Similar to gag
reflex, the patients with MMC class III and class IV (9.04 ±
3.72, 10.48 ± 6.53) had longer successful insertion time than
the patients with MMC class I and class II (5.32 ± 1.67,
7.67 ± 2.50). Contrary to the insertion attempt, although
MMC class IV showed the highest number of attempt
(1.38 ± 1.09), the differences number of attempt among
MMC classes showed no statistical significance (P = 0.133).
Focusing on the vital signs’ change, there was no
statistically significant difference between MMC and each of the
Table 1 Patient’s demographic characteristics
three vital signs, including mean arterial pressure (MAP),
heart rate (HR), and oxygen saturation (O2sat). However,
the percentage of HR change was increased in each higher
MMC classes as follows: MMC class I was 36.36 %, MMC
class II was 42.90 %, MMC class III was 45.45 % and MMC
class IV was 56.25 %. Also, the MAP in the patients with
MMC class III (6, 18.18 %) and MMC class IV (5, 31.25 %)
showed higher percentages than the patients with MMC
class I (2, 9.10) and MMC class II (1, 7.14 %) while there
was an unremarkable change of the O2sat (≤90 %)
throughout the procedure.
The last three outcomes, recorded after pulling the TEE
probe out of the patient’s mouth were oropharyngeal pain
(OP) at 1-h, oropharyngeal pain (OP) at 24-h, and visible
blood on probe tip. According to the OP score 0–10, the
mean score of both OP at 1 h (1.31 ± 1.23) and 24-h (0.78
± 1.15) showed mild pain score and no statistically
significant difference (P = 0.086, P = 0.950). Likewise, 21
(24.71 %) patients were found to have blood on probe tip
as well as no statistically significant difference (P = 0.983).
The data are presented in Table 2.
Correlation between the outcomes and the MMC
Having been identified as statistically significant
variables, gag reflex and successful TEE probe insertion time
were further analyzed using regression analysis.
Age (Mean ± SD)
BMI (Mean ± SD)
Gender- No. (%)
Education - No. (%)
Previous TEE - No. (%)
Cooperation - No. (%)
Anticoagulation - No. (%)
Attempt (Mean ± SD)
Time (Mean ± SD)
Vital Signs’ Change
MAP - No. (%)
O2sat - No. (%)
HR - No. (%)
Throat Pain Score
1-h (Mean ± SD)
24-h (Mean ± SD)
Bleeding - No. (%)
Table 2 Comparison of TEE outcomes among Modified Mallampati Classification
Based on logistic regression, comparing gag reflex
between MMC class I and the others, while the patients with
MMC class II were indicated non statistical significance
(OR 0.567; 95 % CI 0.094–3.423; P = 0. 536), the high grade
MMC such as class III was found to be statistically
significant associated with gag reflex during the TEE probe
insertion (OR 5.231; 95 % CI 1.548–17.670; P = 0.008).
Moreover, although the association was no statistically
significant, the patients with MMC class IV also had a
tendency to have gagging (OR 3.4; 95 % CI 0.840–13.761; P =
0.086). The data is shown in Table 3.
Simple linear regression was performed in order to
identify the association between successful TEE probe
insertion time and the MMC as shown in Table 4. By
using the successful time of MMC class I as the constant
(5.318 s), the results indicated that the high grade MMC
class III (b 3.718; SD ± 1.077; P = 0.001) and IV (b 5.15;
SD ± 1.286; P = 0.000) were statistically significant
correlated with the successful TEE probe insertion time,
whereas the patients with MMC class II were no
statistically significant (b 2.348; SD ± 1.405; P = 0.099). The data
is shown in Table 4.
Based on the study results, the high grade MMC (class
III and class IV) was statistically significant associated
with the gag reflex and the insertion time. These
findings are additional clinical information for performing a
TEE since previous studies mention only operator’s
experience and patient’s cooperation as the key success
factors [1, 4]. However, one of the most important
problems in performing a TEE is insertion of the probe,
especially in the unsedated patients.
During the TEE probe insertion, even though topical
anaesthetic agent has been applied throughout the
oropharynx, gagging still remains in some cases. This
physical reaction is induced by the touch of the transducer
on any six sensitive oropharyngeal parts, including soft
palate, uvula, fauces, posterior pharyngeal wall, back of
the tongue and epiglottis [5, 6]. The effect of gagging
can cause a failure of the probe insertion or aspiration
during the procedure . As reported by Huang, et al.,
the patients who have gagging are tended to have lower
tolerance for esophagogastroduodenoscopy (EGD) than
the patients in the opposite group. They also find out
that the patients with high grade MMC (classes III and
IV) are found to have more gagging than the low grade
MMC patients (classes I and II) . In agreement with
our results, the patients who presented with MMC class
III and class IV had a 5.2–fold and 3.4-fold more
gagging than MMC class I patients. This finding was similar
to the insertion time which also associated with MMC.
Table 3 Correlation between MMC and gag reflex
In reference to our results, the mean time of the
fastest probe insertion was 5.32 ± 1.67 s which was found in
the group of MMC I while the other three groups of the
higher classes showed longer times as in MMC class II
was 2.35 ± 2.5 s (P = 0.099), MMC class III was 3.72 ±
3.72 s (P = 0.001) and MMC class IV was 5.16 ± 6.53 s
(P = 0.000).
Therefore, according to regression equation, Y = ax + b
[23, 24], the successfully inserted time of the patients
with MMC class II, class III and class IV are as follows:
7.67 ± 2.5 s, 9.04 ± 3.72 s, and 10.48 ± 6.53 s. Comparing
to the another study, there is a lack of data on the TEE
probe insertion time, but an approximation is within
1 min .
To the best of our knowledge, even though all
participants were successfully performed the TEE without
sedation, MMC should be considered as one of determining
factors affecting the unsedated TEE’s outcome since it is
related to gagging and probe insertion time. These
correlations may be explained using MMC criteria classified
by oropharyngeal cavity [11–16]. By the view of fully
opened mouth and protruded tongue without any
sounds, MMC class III and class IV allow the examiner
to see only soft palate and maybe uvular because the size
and position of the tongue which are larger and farther
than MMC class I and class II . This specific
anatomy is an obstacle to performing the TEE because of the
compression of the probe which spontaneously creates a
direct pressure on the posterior of the tongue leading to
a spasm of the pharynx, a natural mechanism of choking
prevention [17–20]. Moreover, the narrow
oropharyngeal cavity also affects the procedure in terms of
difficulty passing the TEE probe into esophagus. For these
two reasons, the patients with the narrow oral cavity
(MMC class III and class IV) are tended to experience
Table 4 Association between successful TEE probe insertion
time and MMC
longer successful insertion time than those who have
wider oral cavity (MMC class I and class II).
The other interesting finding was the patients with
MMC class III and class IV had a tendency to have
oropharyngeal pain at 1 h after the procedure (P = 0.086).
This result could be explained based on the successful
insertion time and gagging which were related to MMC.
As mentioned above, the patients with high grade MMC
had narrow oral cavity which might be abraded easily on
oropharyngeal mucous membrane by the TEE probe
during insertion, especially when having gagging. That
is, the patients who present more gagging during the
TEE procedure are likely to experience more
oropharyngeal pain at 1 h after the procedure than others [25–27].
This finding supports the TEE is not only a safe
procedure but also a non-admitted procedure. According to the
TEE guideline, an outpatient can be discharged if there
is non-serious complication after the procedure .
The reduction of gagging during performing
endoscopic procedure has been studied worldwide in order to
increase patients’ tolerance and comfort [14, 15],such as
using a micro TEE probe and intra cardiac
echocardiography probe (ICE) instead of using a conventional probe
[21, 22]. Moreover, Tsuboi et al., claim that performing
an unsedated EGD by passing the EGD probe through
nasal cavity shows better outcomes than passing through
oral cavity . Apart from the equipment and the
passage, Ulusoy and Kucukarslan state that the sitting
position can help the patient to be successfully inserted the
TEE probe . Similar to Samsoon and Young, in the
field of anesthesiology, neck flexion and head extension
are the two important factors facilitating the operator to
successfully intubate endotracheal tube.
However, in a busy non-invasive cardiac testing setting
or a non-anesthesiology setting, the TEE may be
performed without sedation as well as using the
conventional probe and technique. In such a limited resource
setting, MMC can be used for a quick assessment of
gagging which will be helpful in terms of administrating
topical anaesthesia. Moreover, the patients with MMC
class III and class IV may need to be placed in a
particular position of head and neck instead of placing them on
the conventional left lateral decubitus position which
focuses only on aspiration prevention . In summary,
optimizing the unsedated TEE outcomes, the patients
with high grade MMC should be given effective
oropharyngeal anaesthesia and be placed in a proper position.
Limitations of the study
The three main points being considered as the study
limitations are sample size, other factors affecting
gagging, and the subjects’ age. First, our data were
unavoidably analyzed from a small number of patients from
single heart center and the totally unequal subject
numbers in each group. Further study may need to
investigate in a larger sample size. Next, the other factors
affecting gaging apart from the MMC were not included
in the study protocol. These factors may also affect
gagging during TEE probe insertion in the patients with
MMC classes I and II. Last, our results might not be
generally used as a reference for the heart disease
patients of all ages because most participants were middle
aged and cooperative.
Our study demonstrates that MMC is positively
associated with the successful TEE probe insertion time.
Moreover, the high grade MMC patients (MMC class III
and class IV) are found to be correlated with gagging
during the TEE probe insertion and found to have a
tendency toward oropharyngeal pain at 1 h after the TEE.
From these reasons, MMC should be considered as one
of determining factors in the success of unsedated TEE
procedure in the patients with heart disease. Therefore,
in order to optimize unsedated TEE outcomes, the
patients should be assessed MMC which will benefit in
terms of administrating topical anaesthesia.
EGD: Esophagogastroduodenoscopy; HR: Heart rate; ICE: Intra cardiac
echocardiography probe; MAP: Mean arterial pressure; MMC: Modified
mallampati classification; SD: Standard deviation; TEE: Transesophageal
echocardiography; TN-EGD: Transnasal esophagogastroduodenoscopy;
TOEGD: Ransoral esophagogastroduodenoscopy
Available of data and material
Please contact author for data requests.
Miss JK carried out the study, participated in the design of the study and
performed the statistical analysis, participated in the sequence alignment
and drafted the manuscript. Dr. DS was the study consultant. Mrs. TP
participated in the sequence alignment. Mrs. PT participated conceived of
the study, and participated in its design and coordination. All authors read
and approved the final manuscript.
The authors declare that we have no competing interests.
Consent for publication
All authors and participants have signed consent for publication.
Ethics approval and consent to participate
This study was approved by Khon Kaen University Ethics Committee for
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