Anesthetic Induced Middle Ear Pressure Changes And

Original article
Anesthetic Induced Middle Ear Pressure Changes
And Nausea And Vomiting In Children
Undergoing Adenotonsillectomy (Research Paper)
Mustafa ARSLAN 1, Berrin IŞIK 1, Yusuf KIZIL 2, Özgür ÖZSOYLAR 1, Erdem DİNÇ 2,
Mehmet AKÇABAY 1, Yusuf KEMALOĞLU 2
1
Gazi University Faculty of Medicine Department of Anesthesiology and Reanimation, ANKARA
2
Gazi University Faculty of Medicine Department of ENT, Head and Neck Surgery, ANKARA
ABSTRACT
N2O, widespreadly used in anesthesia, increases space
volumes because of its high rate of diffusion and it
increases pressure in non-compliant tissues such as
middle ear cavity. Increase in middle ear pressure is an
undesirable
condition
because
of
its
potential
complications.
The
aim
of
this
cross-sectional
randomized study is to compare effects of N2O plus
desflurane or sevoflurane and remifentanil plus
desflurane or sevoflurane on middle ear pressure and
postoperative nausea and vomiting.
Patients in American Society of Anesthesiologists (ASA)
group I-II aged between 5-18 years undergoing
tonsillectomy or adenotonsillectomy were randomized
into groups according to anesthesia we performed as
desflurane plus N2O group (Group DN, n=15),
sevoflurane plus N2O group (Group SN, n=15),
desflurane plus remifentanil group (Group DR, n=15)
and sevoflurane plus remifentanil group (Group SR,
n=15). Mean arterial pressure (MAP), heart rate (HR)
monitorization of cases and preoperative (T0), after
intubation (T1), before extubation (T2), after extubation
(T3), 30 minutes after extubation (T4) middle ear
pressures (MEP) were measured. Finally, MEP values and
postoperative nausea vomiting (PONV) frequencies
among groups were compared.
T0 measurements of MEP were not different between
groups, but T1 measurements were higher in N2O used
groups than remifentanil used groups. Similar rise in
MEP was observed in remifentanil used groups parallel to
prolonged anesthesia duration. No difference observed
among groups with respect to side effects. There was
MEP difference between two ears in 17 cases with
nausea and vomiting. When left and right MEP values of
17 patients with nausea and vomiting at T3 were
compared, the average of higher cases was 8.9±97.2
and it was -156.8±107.8 for lower cases. The difference
was statistically significant (p<0.0001). In middle ear
surgery, remifentanil plus sevoflurane or desflurane is a
better alternative than N2O for brief surgical
interventions. Major factor in PONV seems to be the
pressure difference between right and left ear
independent of the anesthetic agent used, although
future studies on this subject are required.
Key
Words:
Middle
ear
pressure,
sevoflurane, N2O, remifentanil, PONV
desflurane,
INTRODUCTION
Increase in middle ear pressure (MEP) may cause
complications such as ear pain, transient or
permanent
hearing
loss,
hemotympanium,
disarticulation of stapes, tympanic membrane
rupture, serous otitis media, displacement of
tympanic membrane graft and postoperative
nausea vomiting. These complications increase
costs besides being a disturbing factor for the
patient1–7.
It is well known that nitrous oxide (N2O), which is
frequently used for anesthesia, causes volume
changes in air filled cavities and increases
pressure in noncompliant spaces such as middle
ear cavity1–3,5. Some studies reported that MEP is
considerably increased when N2O is used with
inhalation anesthetics like halothane and isoflurane
or intravenous anesthetics like propofol and
ketamine1,8. Thomsen et al.9 reported that MEP
increased to 340 mmH2O within 30 minutes after
inhalation of 80% N2O; to 220 mmH2O within 38
minutes after inhalation of 60% N2O and to 290
mmH2O within 66 minutes after inhalation of 40%
N2O. Perreault et al.10 reported that MEP was
increased to 400 mmH2O 30 minutes after inhalation
of 66%-70% N2O and 0.5%-1.0% halothane.
There is also a case report about spontaneous
tympanic membrane rupture after N2O use for
anesthesia3. On the other hand it is reported that
in total intravenous anesthesia (TIVA) anesthesia
practice with propofol, fentanyl and ketamine MEP
was also increased but not as much as in N2O
used group8, and N2O addition to halothane
anesthesia had no effect on MEP11.
217
Our search of literature about effects of N2O and
remifentanil used with desflurane or sevoflurane
on MEP and postoperative nausea and vomiting
(PONV), revealed no publication. For that reason
we aimed to study effects of N2O and remifentanil
combined with desflurane or sevoflurane on MEP
and rate of PONV during tonsillectomy and
adenotonsillectomy.
MATERIAL AND METHOD
This
double-blind,
randomized
study
was
conducted by Anesthesiology and Reanimation
Department and Ear, Nose and Throat & Head and
Neck Surgery Department at Gazi University
School of Medicine. The study was confirmed by
the commitee of ethics. The sample consisted of
60 tonsillectomy or adenotonsillectomy indicated,
ASA (American Society of Anesthesiologist) I-II
group cases, aged 5–18 years. Exclusion criteria
were presence of hepatic, renal, cardiovascular
disorders,
drug
allergy,
asthma,
chronic
obstructive pulmonary disease, haematological
disorders, acute or chronic otitis media, current
opioid and anticoagulant usage, history of
previous middle ear surgery and motion sickness.
Subjects were divided into 4 groups each
consisting of 15 patients according to the
randomization list. In the first group desflurane
and remifentanil was used (Group DR, n=15), in
the second group sevoflurane and remifentanil
was used (Group SR, n=15), in the third group
desflurane and N2O was used (Group DN, n=15),
in the fourth group sevoflurane and N2O was used
(Group SN, n=15).
Patients were orally restricted for 6-8 hours before
operation and premedicated with 0.1 mg/kg
midazolam
(Dormicum®)
intramuscularly
30
minutes before operation. In the operating room
intravenous (iv) line obtained through hand
dorsum with 18-20 G cannula and infusion began
with 5 ml/kg Izoleks-P with 5% Dekstroz (Biosel®
Turkey). Continuous monitorization of heart rate
(HR) with electrocardiogram (ECG), noninvasive
monitorization of systolic (SAP), diastolic (DAP)
and mean arterial pressures (MAP), oxygen
saturation
(SpO2)
were
performed
(Odam
Physiogard SM 786 1995 France®). Tympanometric
measurements were obtained with a portable
tympanometer (Interacoustics A/S, Assens DK5610, MT10 Audiometer, Denmark®) from left and
right ears before anesthesia and recorded as
baseline value (T0). Anesthesia induction was
standardized in all groups as 2 minutes
preoxygenation followed with intravenous 2 mg/kg
propofol (Propofol Fresenius 1%®) and 0.5 mg/kg
218
atracurium (Tracrium®). After anesthesia induction,
iv 0.1 μg/kg/min remifentanil infusion with infusion
pump (IVAC 780, San Diego, CA®) and 2–6%
concentration of desflurane (Suprane®) inhalation
inside 4L/min 50% O2/air for patients in group DR,
iv 0.1 μg/kg/ min remifentanil infusion and % 1–2
concentration of sevoflurane (Sevorane®) inhalation
inside 4 L/min 50% O2/air for patients in group
SR, 2–6% concentration of desflurane inhalation
inside 4 L/min 50% O2/N2O for patients in group
DN, 1–2% concentration of sevoflurane inhalation
inside 4 L/min 50% O2/N2O for patients in group
SN. After adequate muscle relaxation patients
were intubated orotracheally and gastric suction
performed after intubation. In all groups, controlled
ventilation started by setting tidal volume as 7
mL/kg, frequency as 12–25 and PAW as 25–30
cmH2O after tube fixation.
During operation, in order to keep HR and MAP
within ± 20 % limits of measurements before
anesthesia induction, which were baseline values,
desflurane and sevoflurane concentrations were
set to 2–6% and 1–2% respectively. In case of
bradycardia 0.015 mg/kg atropine administration
was planned.
At the end of operation after
bleeding control, gastric suction was performed,
inhalation anesthetics were stopped and 4L/min
100% O2 was inhalated. Surgery completion time
and anesthetic agent cessation time were
recorded. Manual respiration with 100% O2 in 4
L/min fresh flow circuit was maintained until
spontaneous respiration was restored. After
beginning of regular respiration, muscle relaxation
was antagonized by iv administration of 0.015
mg/kg atropine and 0.05 mg/kg neostigmine.
With restoration of adequate spontaneous
respiration,
patients
were
extubated
and
transferred to the recovery room.
Heart rate (HR), MAP, SpO2 datas were recorded
before and after induction and every 5 minutes
until the end of the operation. MEP measurements
repeated just after induction (T1), before
extubation (T2), after extubation (T3) and 30
minutes after extubation (T4). PONV was evaluated
at T3–T4 intervals. Investigators evaluating PONV
and MEP were blinded to the anesthetics used and
investigators performing anesthesia practice were
blinded to the MEP measurements and PONV. In
recovery room HR, MAP, SpO2 were also
monitorized and MEP was measured 30 minutes
after extubation. In case of nausea or vomiting iv
metochlopramide 0.15 mg/kg (Metpamid®) was
administered for antiemesis.
Obtained data were analized by a computer based
statistical programme. Statistical analysis of variance
(ANOVA) and Student-Newman- Keul multiple
Group DR
Group SR
110
Group DN
Group SN
100
90
80
70
30
15
45
60
Before
extubation
Extubation
Time (min)
30
25
20
15
5
10
Entubation
60
Control
Group DN
Group SN
130
110
90
70
Figure 1. Mean arterial pressure values
Change in mean HR values with time are given in
Figure 2. There was no significant difference
identified among groups. If changes within groups
were compared with the control values, none of
the recorded HR values after anesthesia induction
and during operation were significantly different.
Preoperative MEP values which were assigned as
baseline values (T0) was not significantly different
among groups. T1 measurements of right MEP in
group DN and group SN were significantly higher
than in group DR and they were significantly lower
in group SR than in group DN (p=0.002, p=0.026,
p=0.009, respectively). T3 and T4 measurements
of right MEP in group DN and in group SN were
significantly lower than in group DR (T3 p<0.0001,
p<0.001; T4 p<0.0001, p=0.026, respectively)
15
45
60
B e fo re
e x tu b a tio n
E x tu b a tio n
Time (min)
30
25
20
15
10
5
E n tu b a tio n
C o n tr o l
I n d u c tio n
There was no significant difference in demographic
features among groups (Table 1). MAP changes in
time are given in Figure 1. When changes in MAP
averages of groups in time were compared, no
difference identified among groups. If changes
within groups were compared with control values,
none of the recorded MAP values were
significantly different.
Induction
Group DR
Group SR
150
50
RESULTS
Mean Arterial Pressure
(mmHg)
and in group SR (T3 p<0.009, p<0.026; T4 p=0.001,
p=0.026, respectively), (Table 2).
H e a r t R a te
comparison test were applied to determine the
significant differences among the groups. Bonferroni
adjustment was used in the comparisons of
intragroup values of MEP, MAP and HR in which
the time factor was identified as important
through repeated measures of variance analysis.
Chi-square and Fisher’s exact test compared
gender and postoperative side effects of the
groups. P values <0.05 accepted as statistically
significant.
Figure 2. Heart Rate values
When right MEP changes within groups were
compared, there was a significant increase in
group DN and group SN at T1 and T2
measurements and a significant decrease at T4. In
group DR there was significant increase of right
MEP values at T2 and a significant decrease at T4.
In group SR a significant increase in right MEP
values was observed at T2 (Table 2).
When baseline-T0 left MEP values were compared,
there was no significant difference among groups.
At T1, T3 and T4 left MEP in group DR was
significantly lower than left MEP values in group
DN (p=0.003, p=0.0001, p=0.0001, respectively)
and group SN (p=0.034, p=0.009, p=0.016,
respectively). When MEP values in group SR were
compared to grup DN; they were significantly
different at all measurements except T0 (p=0.012,
p=0.003, p=0.029, p=0.026, respectively), (Table 3).
When left MEP changes within groups were
compared, there was a significant increase in
group DN and group SN at T1 and T2
measurements and a significant decrease at T4. In
group DR and group SR there was a significant
increase at T2 and a significant decrease at T4
(p<0.05), (Table 3).
Nausea and vomiting were the only side effect
encountered. There was no statistically significant
difference among groups when frequency of
nausea and vomiting were compared (Table 4).
When left and right MEP values of 17 patients with
PONV at T3 were compared, the average of higher
cases was 8.9±97.2 and it was -156.8±107.8 for
lower cases. The difference was statistically
significant (p<0.0001), (Table 5).
219
Table 1. Demographic Datas (Mean± SD, n)
Characteristics
Group DR
(n=15)
8.4±3.2
6/9
29.8±9.8
129.0±16.2
77.3±13.5
65.9±14.3
Age (yr)
Gender (female/male)
Weight (kg)
Height (cm)
Duration of anesthesia (min)
Duration of surgery (min)
Group SR
(n=15)
7.4±3.5
5/10
24.4±10.4
121.4±15.4
74.6±11.5
60.9±13.3
Group DN
(n=15)
7.5±2.5
7/8
26.5±6.3
116.6±15.3
74.0±7.6
61.5±7.8
Group SN
(n=15)
7.3±3.1
6/9
26.3±10.5
121.6±16.3
76.9±13.4
65.6±15.4
Table 2. Right ear MEP measurements (Mean±SD)
MEP
T0
T1
T2
T3
T4
Group DR (n=15)
-60.5±31.4
-19.4±65.2
Group SR (n=15)
-116.2±114.2
-41.6±144.2
111.1±91.3‡
-12.7±70.1
-151.2±53.6‡
58.0±130.1‡
-57.6±85.8
-169.3±83.2
Group DN (n=15)
-48.8±96.6
97.9±101.1*,‡
122.9±102.9 †,‡
-197.9±121.0*,†
-259.±62.0*, †,‡
Group SN (n=15)
-76.5±85.2
22.4±144.5*, ‡
127.7±129.8 ‡
-160.8±106.3*, †
-224.6±57.1*, †,‡
P<0.05, * Group DR, † Group SR Compared to the values of the other groups, ‡ Compared to the values T0 preoperative (T0),
30 minutes after extubation (T4), MEP: Middle ear pressure
after intubation (T1), before extubation (T2), after extubation (T3),
Table 3. Left ear MEP measurements (Mean±SD)
MEP
T0
T1
T2
T3
T4
Group DR (n=15)
-78.3±70.9
-45.3±98.1
79.0±166.4 ‡
13.3±119.4
-156.5±75.9‡
Group SR (n=15)
-117.4±117.0
-69.2±154.9
27.5±118.9 ‡
-72.5±100.7
-198.8±82.9 ‡
Group DN (n=15)
-71.3±123.8
85.5±126.4*, †,‡
142.5±151.6 †,‡
-173.0±95.2*,†
-269.6±33.6*, †,‡
Group SN (n=15)
-84.5±77.1
24.3±122.5*, ‡
104.6±109.1‡
-154.8±95.8*, †
-222.3±53.2*, ‡
P<0.05, * Group DR, † Group SR Compared to the values of the other groups, ‡ Compared to the values T0
preoperative (T0), after intubation (T1), before extubation (T2), after extubation (T3),
30 minutes after extubation
(T4)
MEP: Middle ear pressure
Table 4. Nausea and vomiting findings [n (%)]
Parameters
Group DR (n=15)
Group SR (n=15)
Group DN (n=15)
Group SN (n=15)
5 (33.3)
4 (26.7)
4 (26.7)
4 (26.7)
6 (40)
4 (26.7)
5 (33.3)
5 (33.3)
Nausea
Vomiting
Table 5. Right and left ear pressure measurements of vomiting patients
Patients with PONV
Group DR
Group SR
Group SN
left
right
left
right
left
right
left
1
2
53.0
6.0
-66.0
191.0
-116.0
25.0
8.0
-299.0
-15.0
-290.0
-243.0
38.0
7.0
117.0
94.0
-213.0
3
4
5
-116.0
-2.0
-
-66.0
151.0
-
-294.0
-214.0
-
-181.0
-110.0
-
45.0
-263.0
-
-56.0
-102.0
-
-15.0
-186.0
-115.0
-205.0
-31.0
-50.0
DISCUSSION
In our study there was an increase in MEP values
in both remifentanil and N2O used groups, while
the latter resulted in an earlier increase. PONV
frequency was similar among groups although
there was a significant difference in mean right
and left MEP values between patients with PONV.
Armstrong et al.6 stated a relation between
positive middle ear pressure and ear symptoms.
An increase in MEP values from 40.8 to 68 mmH2O
220
Group DN
right
resulted with ear fullness and hearing loss in most
of the cases. Pressures between 204–408 mmH2O
caused restlessness and tinnitus even pain and
vertigo, while pressures above 408 mmH2O
caused severe pain, tinnitus and vertigo.
N2O which is widely used in inhalation anesthesia,
rapidly diffuses into spaces causing volumetric
increase in flexible tissues and pressure increase
in unflexible tissues like middle ear due to high
blood gas partition coefficient1-3,7,8. Thomsen et
al.9 showed that MEP values changed according to
N2O inhalation time and concentration. Chinn et
al.12 evaluated MEP change ratios in 138 cases
aged between 6 months and 9 years by taking
measures in every 5 minutes during anesthesia
starting before anesthesia. MEP change ratio was
found as 46% in only halothane used group, while
it was 38% in halothane and N2O used group.
Kubota et al.8 determined that MEP values
reached maximum 60 minutes after TIVA with
propofol, fentanyl and ketamine. On the other
hand, Gates and Cooper13 informed that N2O use
had no significant effect other than halothane use
only.
In our study, N2O resulted in an earlier increase in
MEP values, while remifentanil also caused a
similar but gradual increase in MEP values.
N2O use is not the only factor acting on MEP
values in operations under general anesthesia.
Physiological differences between individuals are
important for passive opening of eustachian tube
during positive pressure administration. Elam et
al.14 showed a correlation between middle ear
positive pressure regulation and mastoid bone
dimensions during N2O anesthesia. In case of
eustachian dysfunction such as inflammation,
infection or scar contracture, there is no change in
MEP13. It is reported that during spontaneous
respiration, N2O administered with mask or by
intubation has no effect on severity of effusion
and ventilation technique used during anesthesia
does not change MEP values15. Koivinen et al.7
reported that N2O increased middle ear pressure
but had no effect on effusion. Another factor
affecting tympanometric measurements is the
position of the patient. In our study, in randomly
assigned groups MEP values before anesthesia
were similar, effusion was not present and similar
ventilation technique was used. In all patients,
tympanometric measurements were made in
supine
position
which
impeded
significant
differences among groups. Several studies showed
that duration of N2O administration had influence
on MEP values. Kubota et al.8 reported that
although MEP values were increased in TIVA
administered cases with propofol, fentanyl,
ketamine when 60% N2O added MEP was
increased significantly just after induction of
anesthesia and reached to its upper limit 36
minutes later.
In our study, in desflurane or sevoflurane plus
N2O used groups MEP values in early period (T1)
were higher than in desflurane or sevoflurane plus
remifentanil used groups, while after anesthesia
MEP values (T4) showed greater decrease.
Operation durations were similar in different
groups but with increase in operation duration
MEP values were also increased in both
remifentanil and N2O used groups.
Eustachian tube blockage during anesthesia
recovery causes negative pressure. It is shown
that negative pressure remained up to 48 hours
after anesthesia in a case report who had
tympanic membrane rupture after anesthesia with
66–70% N2O/34–30% O27. Blackstock et al.16
reported that first day after administration of 66%
N2O for 17–100 minutes (mean 47 mins) with
halothane or isoflurane, negative middle ear
pressure arised in one ear or both ears of all
cases. Chinn et al.17 found that single use of
halothane or halothane with N2O made no
significant difference in MEP values. In another
study, Chinn et al.12 reported that barometric
effects of N2O became obvious immediately after
induction of anesthesia. In our cases, MEP values
increased more rapidly in N2O used groups and
decrease was greater after anesthesia. Since MEP
values were measured until 30 minutes after
extubation, exact time of return to baseline values
was not clear.
Recent studies report that PONV is a major
problem with a 30% occurance rate if antiemetic
medication was not administered. Frequency of
PONV depends on many factors such as age,
gender, body weight, presence of motion sickness
history,
gastric
fullness,
operation
site,
concomitant pathologies, duration of anesthesia,
method of anesthesia and anesthetic agents4,5.
Gastric distention, severe postoperative pain and
narcotic analgesic use are factors adversely
affecting nausea and vomiting during anesthesia
practice. Middle ear surgery is one of the
operations with high rate of PONV5. Cases with
preoperative remifentanil infusion has 22.7–
31.9% rate of PONV18. N2O used in anesthesia
also increases rate of PONV by causing barometric
changes5,11. In a meta-analysis Tramer et al.11
reviewed 24 studies including 2478 patients and
reported that removing N2O during general
anesthesia decreases PONV incidence in high risk
patients. Gastric distention during N2O use is an
important factor increasing nausea and vomiting
besides its central effects5. In our study
demographic features such as age and gender
were similar in all groups. By standardization of
surgery and anesthesia techniques and excluding
risk factors increasing nausea and vomiting, we
aimed to control the confounding effects. We
suggest that gastric suction in all groups after
intubation and before extubation prevented
nausea and vomiting caused by gastric distention.
In our study, there was a similar rate of PONV
both in remifentanil and N2O used groups.
221
The mechanism of nausea and vomiting due to
middle ear pressure changes is not exactly known.
But rapid changes in middle ear pressure may
play a role in PONV by rapid pressure reflection to
labyrinth and vestibule via round window1. In our
series right and left middle ear pressure values
were significantly different in cases with nausea
and vomiting that’s why we concluded that
difference in middle ear pressures of right and left
ear causes nausea and vomiting.
As a result, N2O use seems to be inappropriate for
brief operations because it inceases MEP.
However, in long term operations N2O used with
remifentanil has no effect on MEP as well as on
nausea and vomiting. Difference between right
and left MEP values is an important factor
increasing nausea and vomiting frequency and this
should be further supported by future studies with
larger sample size.
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Correspondence:
Mustafa ARSLAN M.D.
Gazi University Faculty of Medicine, Beşevler-Ankara
e-mail
: [email protected]
Arriva date
: 12.06.2008
Acceptance date : 25.10.2008