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Evaluation of Lateral Head Rotation on Eficacy of Face Mask
Ventilation during Induction of Anesthesia in Children
Alireza Ebrahim Soltani1, Mohammad Amin Karjalian2, Fazeleh Majidi3, Mohammad Saatchi4,
Mohammad Reza Khajavi2*
1Department of Anesthesiology, Children’s Medical Center, Tehran University of Medical Sciences, Tehran, Iran.
2Department of Anesthesiology, Sina Hospital, Tehran University of Medical Sciences, Tehran, Iran.
3Research Development Center, Sina Hospital, Tehran University of Medical Sciences, Tehran, Iran.
4Department of Epidemiology & Biostatistics, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran.
ARTICLE INFO
Article history:
Received 10 February 2022
Revised 03 March 2022
Accepted 17 March 2022
Keywords:
Mask ventilation;
Head rotation;
Neutral position;
Tidal volume
ABSTRACT
Background: The head's position during mask ventilation on the time of anesthesia
induction in children may improve the lung ventilation.
Aim: Current study was designed to verify whether lateral head rotation improves
face mask ventilation efficiency during anesthesia induction in children.
Methods: Fifty-six patients aged 1-4 years, candidate for elective surgery, were
randomly divided into two equal groups. During induction of general anesthesia, face
mask lung ventilation of patients continued with pressure-controlled mode, at a peak
pressure level of 10 cmH2O for children 13-24 months and 14cmH20 for children
24-48 month. In patients in the N group, the head position during ventilation was
initially in the neutral position for one minute, then the head was axially rotated 45-
degree to the right position for one minute and pulmonary ventilation continued in
this position, then the head was rotated again to the neutral position and ventilation
continued for one minute. In group R patients, mode and time of ventilation was the
same, but the order of head placement was first in the lateral rotated to the right, then
neutral and then lateral rotated to the right. The primary outcome was the
measurement of expiratory tidal volume in each position.
Results: Generally, the mean measured expiratory tidal volume did not change in the
neutral position compared to laterally rotated head position, 256.6 vs. 233.5 ml:
difference -23.1 [95% confidence interval: 10.8 to 39.4 ml]. Also, the change of head
position from lateral to neutral position did not show a significant change in the mean
expiratory tidal volume, 232.28 vs.247.86 ml: difference -15 .82 (p= 0.4).
Conclusion: The rotation of the head to the lateral position during induction of
anesthesia in apnoeic children 1-4 years old could not improve the efficiency of mask
ventilation relative to the neutral head position.
t the time of induction of anesthesia in pediatric
patients, the upper airway is often obstructed ,
and, mask ventilation become difficult and
sometimes impossible. In these critical moments,
applying the appropriate skill in lung ventilation is very
important in airway management. Healthy children
usually do not have difficult airway. The occurrence of
unpredicted difficult bag mask ventilation in pediatric
patients is 7% [1]. According to previous studies, there is
no connection between the difficult mask ventilation and
the rate of difficult intubation, as the incidence of difficult
direct laryngoscopy in these patients varies from 0.06%
to 3% [2-3]. To optimize mask ventilation, physicians
typically use the oropharyngeal airway, extending the
A
Research Article
Archives of Anesthesiology and Critical Care (Summer 2022); 8(3): 188-192. 189
patient's head and using several maneuvers such as chin
lift, jaw thrust, lateral position, and two hands to improve
mask ventilation [4-5].
The axial head rotation has been the subject of many
studies to improving the mask ventilation.
In adult apnoeic anesthetized patients, head rotation
significantly improved mask ventilation efficiency
compared with the neutral head position [6]. In children
with obstructive sleep apnoea due to adenotonsillar
hypertrophy, placing patients in a lateral position and
applying the necessary airway maneuvers improves
airway management during induction of anesthesia [7].
Theoretically, turning the head to one side may open the
airway by moving the tongue and epiglottis. This study
intends to investigate the efficacy of lateral head rotation
on mask ventilation in 1-4-year-old pediatric patients
without an underlying problem during apnea at
anesthesia induction.
Methods
This interventional study was conducted from
December 2019 to February 2020 in the Children's
Medical Center, Tehran, Iran. The Ethics Committee of
the Tehran University of Medical Sciences had approved
the study protocol (protocol number:
IR.TUMS.CHMC.REC.1398.100). Informed consent
was received from the parents. The investigators adhered
to Helsinki's declaration- ethical principles for medical
research involving human subjects - throughout the
study.
Study Design: This is a randomized clinical crossover
study.
Inclusion criteria: This study was conducted on 56
patients ASA I, age 1-4 years old, candidates for elective
Urologic and Orthopedic surgery under general
anesthesia.
Exclusion criteria: Children with difficult airway such
as limited head rotation or neck extension, a full stomach,
history of tracheal or laryngeal injury, any anatomical
abnormality in the chest, skull, and cervical spine
myopathies, were excluded.
Eligible patients were randomly divided into N and R
groups. Randomization was performed by creating a
series of envelopes containing group assignments. Papers
containing "Group N" or "Group R" were placed in a
sealed envelope. Immediately before the induction of
anesthesia, the envelope was opened. Thus, the study
staff did not know the group assignment before induction
of anesthesia. Standard monitoring (EKG, blood
pressure, ETCo2 and pulse oximetry) were applied for all
patients. Peripheral intravenous access was provided for
all children in the ward. Initially, pre-oxygenation by
flow rate of 6L min1 was started for all patients through
a circular breathing system and anesthesia face mask until
the expired oxygen fraction reached 0.9. For all patients,
induction of anesthesia was performed with midazolam
(0.05 mg / kg), fentanyl (1 to 2 μg / kg), thiopental sodium
(4 mg/ kg) and then atracurium (0.5 mg / kg). Four
minutes after muscle relaxant injection, general
anesthesia was maintained in the supine position without
any shoulder roll with inhaled sevoflurane.
After induction of anesthesia and the onset of apnea,
which is evident by the cessation of airflow and
respiratory effort, mask ventilation with pressure-
controlled ventilation (PCV) by an anesthesia ventilator
with ten breaths per minute, inhalation to exhalation ratio
1: 2 was performed. Peak inspiratory pressure (PIP) was
set at 10 cmH2o for children 13-24 months and 14
cmH2ofor children 2-4 years, with no positive expiratory
end pressure. The patient mask was held in place by an
experienced anesthesiologist (with more than 20 years of
experience) with both hands in such a way as to maintain
airway optimization throughout the ventilation protocol.
The mask ventilation was performed in group N, in the
neutral head position for 1 minute (step 1), then the head
was rotated axially to the right and ventilation continued
in this position for 1 minute (step 2) and finally the head
was returned to the neutral position, mask ventilation
continued for another 1 minute (Step 3). In group R
patients, the setting of ventilator and the mask ventilation
method were similar to group N patients, except that the
order of head placement was first turned to the right,
neutral, and then turned to the right position. If
ventilation of the lungs was not possible for at least four
consecutive breaths, as proven by the lack of movement
in the chest wall and the disappearance of the
capnographic wave, the next position of the head would
be applied. Then, if lung ventilation is not possible in the
next four consecutive breaths in the next position, the
study in these patients is terminated and airway
management continues routinely. If lung ventilation is
detected in the next position of the head, the study
protocol continued as planned. At any time during the
study, if the patient's Spo2 decreases to 94% or the
patient's ETCo2 increases to more than 50 mm Hg, the
study is terminated and routine airway management
resumes.
For each head position, expiratory tidal volume was
recorded, and the mean of these volumes was intended
for analysis.
Statistical analysis
To calculate the sample size, we used the study of Park
HS et al. [8] with considering the error level of 5%, power
of 80%, and effect size =35%, the sample size was
estimated to be 28 patients in each of the two groups.
Means and standard deviations (SD) were calculated
for continuous variables and frequency and percentage
for categorical variables.
Variables were tested for normal distribution and the
paired t-test. All analyses were performed at 0.05
significance levels using SPSS ver. 22.0 for Windows
(SPSS, Chicago, IL, USA).
190 Ebrahim Soltani et al.: Effectiveness of Lateral Head Rotation during Pediatric Mask Ventilation
Results
At the end of the study, the data of fifty-six pediatric
patients who were randomly assigned to the R or N group
from December 2019 to February 2020 were collected
and analyzed (Figure 1).
Figure 1- Flow chart of the eligible patients
During this study, none of the patients had Spo2 less
than 94% or ETCo2 more than 50 mmHg. None of the
patients had any specific complications associated with
the treatment protocol in this study. The mean age of
children included in the study was 32.67±9.68 months
(range 14 to 48) months.
Basic characteristics of patients described in (Table 1).
Table 1- Demographic Data of patients
variable
overall
Group N
Group R
Male/female
28/28
28
28
Age13-24 mo
16
7
9
Weight, kg
9.3±1.2
8.6±1.5
9.2±1.4
Height, cm
73.9±5.2
72.7±5.1
71.9±4.6
Age25-48 mo
40
21
19
Weight, kg
14.6±3.2
14.7±2.4
14.5±3.1
Height, cm
95.5±6.2
95.3±4.7
96.2±5.7
N, neutral; R, lateral head rotation
Because there is a difference in the anatomy of the
airways, resistance, and compliance of the respiratory
system between 12-24-month-old children and 24-48-
month-old ones, thus data for children between 1 to 2
years old was evaluated separately, and children aged 2-
4 years were examined together.
Correlation of expiratory tidal volume in Neutral and
Rotated position with age and gender was presented in
(Table 2-3).
Assessed for
eligibility (n=56)
Excluded (n=0)
Analysed (n=28)
Excluded from analysis (give
reasons) (n=0)
Allocated to intervention (n=28)
Received allocated
intervention (n=28)
Analysed (n=28)
Excluded from analysis (give
reasons) (n=0)
Allocated to intervention (n=28)
Received allocated
intervention (n=28)
Allocation
Analysis
Randomized (n=56)
Archives of Anesthesiology and Critical Care (Summer 2022); 8(3): 188-192. 191
Table 2- Correlation of mean expiratory tidal volume with age and gender in group N
Variable
N1
R0
N2
R0-N2
P value
VTE ml
242.68±97.9
233.46±89.1
256.57±93.7
-23.9±9.1
0.9
male
265.20±54.61
254.87±66.32
268.07±87.56
-14.2±8.2
0.8
Female
243.31±65.34
230.31±54.65
243.31±62.19
-11.3±8.4
0.5
Age Group
Age< 24 mo.
170.14±17.24
176.14±28.79
190.71±18.34
-26.6±8.5
0.6
Age>24 mo.
266.86±21.67
265.90±36.49
278.52±45.23
-13.4±7.8
0.4
N, neutral; R, lateral head rotation, VTE, expiratory tidal volume (mean ± SD); mo., month
Table 3- Correlation of mean expiratory tidal volume with age and gender in group R
Variable
R1
N0
R2
R1-N0
P value
ETV ml
232.28±97.9
247.86±89.1
237.86±53.7
-15.2±8.2
0.4
male
221.20±54.61
234.87±66.32
230.07±87.56
-13.4±9.3
0.8
Female
242.51±65.34
256.31±54.65
249.32±62.19
-14.7±9.1
0.5
Age< 24 mo.
172.22±17.24
186.14±38.49
168.71±18.34
-14.3±9.1
0.4
Age>24 mo.
246.86±27.67
262.72±46.49
258.42±45.23
-24.7±18.1
0.3
N, neutral; R, 45-degree head rotation, VTE, expiratory tidal volume (mean ± SD); mo., month
According to table 2&3, the VTE changes from a
neutral position to a rotated position are minimal. As the
forty-five degrees’ head rotation even reduces the
expiratory tidal volume slightly.
We also investigated the effects of lateral rotation of the
head on the rate of VTE changes according to the sex and
age of patients, which with the intervention of these
variables, no significant change in the rate of VTE was
observed.
Discussion
In this clinical study, the effect of lateral head rotation
during mask ventilation on expiratory tidal volume was
evaluated, and we found that 45° degree head rotation
slightly reduced VTE compared to the neutral head
position in apnoeic paediatric patients.
Upper airway obstruction at the beginning of general
anesthesia induction is one of the most common problems
that cause difficult mask ventilation. In apnoeic patients
with supine position, the mechanisms of upper airway
obstruction are reduced muscle activity of the
oropharyngeal structure and their gravitational effects on
the anterior structures of the upper airway [9]. The effect
of body position and head rotation in adult patients with
and without obstructive sleep apnea on the shape, size
and the upper airway collapsibility has been studied by
imaging techniques [10-11]. These studies' essential
findings indicate that, head rotation and lateral position
had increased circularity of the upper airway shape and
anteroposterior dimensions of the retro-glossal and retro-
palatal region.
In 2017, Itagaki et al, evaluate the effect of 45-degree
right-head rotation on the performance of facial mask
ventilation in adults patients with apnoea under general
anesthesia, and found that rotating the head from neutral
to lateral position significantly increased VTE [7]. We do
a similar study in anesthetized apnoeic children 1-4 years,
but VTE slightly decreased in head rotation. An initial
study of 17 healthy infants between 1 and 4 months of
age showed no significant improvement in tidal
respiration parameters in head rotation [12]. Due to this
physical structure, children's airways are prone to
dynamic airway changes when the head rotates laterally
[13]. In addition, the larynx of children is very narrow
and funnel-shaped, and in terms of anatomical position
that is higher than the larynx of adults and it is at level
C2-C4. The epiglottis cartilage is relatively long and stiff
at this age, with rotation of the head and neck to the sides,
the airway in the pharynx and larynx may predispose to
collapse.
The patients in this study all received general
anesthesia and muscle relaxants and underwent
ventilation with PCV mode. The use of a muscle relaxant
will minimize the breathing resistance of the anesthesia
machine and make the measurement of respiratory
volumes more accurate.
In the case of PCV breathing mode with fixed peak
inspiratory 14 CmH2o pressure for children 2-4 years
old, this pressure is lower than peaked airway pressure in
children, and we are worried about gastric insufflation
during ventilation. According to JH Lee et al, during
mask ventilation under general anesthesia the median
inspiratory pressure that lead to gastric insufflation in age
1-5 year is 16-18 CmH2o, so in this pressure, the
probability of gastric insufflations decreases. However, it
cannot be ignored, and this complication has not been
investigated in this study [14].
Finally, it should be noted that structural and
anatomical differences between children and adults in the
upper airways increase the likelihood of children's upper
airway obstruction in lateral head rotation.
192 Ebrahim Soltani et al.: Effectiveness of Lateral Head Rotation during Pediatric Mask Ventilation
Conclusion
As a result, forty-five degrees of head rotation in
anesthetized 1 to 4-year-olds did not increase expiratory
tidal volume and could not improve mask ventilation
efficiency relative to ventilation at neutral position.
Limitation
We only studied paralyzed patients at the beginning of
anesthesia. Therefore, the results of this study cannot be
applied to non-paralyzed patients in whom head rotation
may open the upper airway and improve ventilation.
We just studied children without any difficulties in the
upper airway; therefore, our findings cannot be applied to
pediatric patients who have difficulty in upper airway and
cervical neck movement.
Acknowledgment
The authors would like to thank the statistics
consultants of the Research Development Center of Sina
Hospital for their technical assistance.
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