Macintosh Laryngoscope Assisted Flexible Fiberoptic Endotracheal intubation Versus Flexible Fiberoptic Endotracheal Intubation alone for modified Mallampati III & IV Patients: A Prospective Randomized Controlled Study
Mohamed ghanem* and Alaa Mazy
Mansoura Urology and Nephrology Center-Mansoura University, Mansourah Dakahlia, Egypt
Submission: December 03, 2018; Published: December 13, 2018
*Corresponding author: Mohamed ghanem, Mansoura Urology and Nephrology Center Mansoura University, Mansourah Dakahlia, Egypt
How to cite this article: Mohamed G, Alaa M. Macintosh Laryngoscope Assisted Flexible Fiberoptic Endotracheal intubation Versus Flexible Fiberoptic
Endotracheal Intubation alone for modified Mallampati III & IV Patients: A Prospective Randomized Controlled Study. J Anest & Inten Care Med. 2018;
8(1): 555728. DOI: 10.19080/JAICM.2018.08.555728
Background: The intubation difficulty of using the flexible FOB could be due to the inability to visualize the glottis and/or failure to advance and railroad the endotracheal tube. The combined use of Macintosh laryngoscope with the flexible FOB could be a safe technique that facilitate the flexible FOB intubation function in non-relaxed spontaneously breathing patients predicted to be difficult for endotracheal intubation.
Methods: A prospective randomized controlled study included 100 patients predicted to be difficult for airway intubation, ASA physical status Ӏ-III, aging 18-65 years. Patients were randomly allocated into two groups 50 patients each, the control group (Group F) in which flexible- video assisted-FOB was used alone and the study group (Group MF) in which combined Macintosh - flexible-video assisted-FOB used for endotracheal intubation under inhalational general anesthesia out of any muscle relaxant use. The study compared the techniques for endotracheal tube insertion time, 1st trial success rate, number of attempts, complications, and hemodynamic changes between both groups.
Results: There were significant decrease in endotracheal tube insertion time Group MF (32.04± 7.8) compared to Group F (68.6 ± 12.24), significant increase in 1st trial success in Group MF 49 (98%) compared to Group F 41 (82%), with acceptable Intubation conditions and hemodynamics for both groups. Conclusion: The combined use of Macintosh laryngoscope with the flexible FOB in predicted difficult endotracheal intubation conditions provides significant decrease in endotracheal tube insertion time (near 50% reduction), significant increase in 1st endotracheal intubation trial success rate, acceptable intubating conditions and hemodynamic stability compared to flexible FOB alone.
Keywords: Endotracheal; Flexible; Fiberoptic; Intubation; Laryngoscopy; Macintosh
a. The Study Question: Could preliminary Macintosh laryngoscopy improve the performance of flexible Fiberoptic Video Assisted Laryngoscope (FVFOB) during predicted difficult intubation?
b. The study Value: Up till now this is the only clinical research studied the value of combine FOI with Macintosh laryngoscope in difficult intubation predicted airway.
c. The Study Findings: Combined Macintosh with FVFOB provided Significant decrease in EET insertion time, significant increase in 1st trial success, accepted Intubation conditions, and hemodynamics during predicted difficult intubation.
d. Meaning: Macintosh laryngoscope with the FVFOB is feasible and safe intubation technique in spontaneously breathing non-relaxed patients having predicted difficult airway intubation (PDEtt).
Variety of devices and new technologies have been developed as intubation tools but still not available in every operative theater. Indirect laryngoscopy methods such as FOB and video laryngoscopes have recently been added to the guidelines by the American Society of Anesthesiologists for management of predicted difficult endotracheal intubation (PDEtt) . Non- tongue protrusion modified Mallampati score (NT-MMT)  and thyromental distance are reliable indicators for airway difficulty prediction for endotracheal intubation. A golden rule during predicted difficult intubation and/or difficult mask ventilation is that airway should be safely secured while the patient is still awake. Difficulty during FOB could be due to inability to visualize glottis or to advance and railroad the endotracheal tube (Ett). The success rate of using Macintosh laryngoscope alone versus flexible
FOB in predicted difficult airway intubation were respectively
26.1% and 92.6% (p < 0.01). 
The combined use of Macintosh laryngoscope with the FVFOB
can facilitate the FOB intubating function and increases its success
rate in non-relaxed spontaneously breathing patients PDEtt. Aim
of the work: To improve flexible FOB reliability and success rate
during difficult intubation conditions.
After study protocol approval by the Human Studies
Committee at the University Mansoura International research
board approved, this study (IRB) Code Number: R/17.08.102,
date 10/9/2017, written informed consent was obtained from all
subjects participating in the trial, the trial was registered prior
to patient enrolment at the ClinicalTrials.gov (NCT03310866),
registration date 16/10/ 2017.
A prospective randomized controlled study on Patients aged
18 to 65years of ASA physical status I to III. All Patients airway was
evaluated by NT-MMT airway score (2) and thyromental distance
(3) by anesthetists not involved in airway intubation at the
preoperative round. The study was designed as a parallel 2-arm,
comparing FVFOB [KARL STORZ (FIVE) Flexible Intubation Video
Endoscope, C-MAC® Monitor, 8403, zx] (control group=Group
F) versus combined FVFOB and Macintosh laryngoscope (study
group= Group MF) for PDEtt scheduled for oncology surgery
under general anesthesia. After pilot study of 40 cases 20 for each
group, sample size obtained using G power program total number
of 100 patients 50 patient for each group, patient enrolment,
exclusion, and group allocation was clarified in the study chart
All patients were ASA I-III. Airway criteria: should be of
both Modified Mallampati (NT-MMT) Airway score III, or VI
with thyromental distance ≤ 5cm (PDEtt), both sexes, aged 18
to 65 year’s old, Scheduled for elective oncology surgery under
general anesthesia. Exclusion criteria: Patients with preoperative
hemodynamic instability or heart failure, pulmonary diseases
pregnancy. Suspected cervical fracture, Deformities of the tongue,
mouth, mandible, larynx and maxilla, Prior history of surgery in
these regions. Morbid obese BMI> 35, obstructive sleep apnea
patients. History of malignant hyperthermia, and allergy to
general anesthetics or opioids.
Airway of the Patients was evaluated using NT-MMT by
anesthetists who were not involved in airway intubation at the
preoperative examination, all patients fasted 6 hours for solid and
2 hours for water before surgery, morning of surgery IV cannula
was inserted in the ward before sending the patient to operative
theater then preloading with 500 ml Normal saline IV infusion,
Glycopyrrolate (7μg/kg IV) was given 20 minutes before airway
management for suitable clear dry vision and better quality of
topical anesthesia during FVFOB.
Sterile FVFOB was attached to electric power light source
vision clarity, anterior and posterior tip movement checked,
portex Ett (7.5 mm ID in males, 7 mm in females) railroaded
over it. Sterile FVFOB specific airway, Sterile Macintosh direct
laryngoscope, its light source check, sterile effective suction
machine with a sterile suitable suction catheter attached, size 3
and size 4 sterile laryngeal mask in case needed.
In the recovery room pulse oximeter O2 saturation monitor
was connected then Airway local anesthesia nebulization sitting
Using lidocaine 1mg/kg of 2% lidocaine  solution nebulized
over 5 minutes via electric nebulizer was done in semi-sitting
position in the recovery room 20 minutes prior intubation over 5
liters O2/minute flow.
In the operative room Patients were positioned in the flat
supine neutral head position, Then basic monitoring devices
were connected includes: Non-invasive blood pressure cuff,
Electrocardiography (ECG), pulse oximetry and End tidal Co2
(EtCo2) side-stream Capnogram connected to the oxygenation
Mask-circuit complex, after that 1mg/kg lidocaine 2% solution
gurgle for 60 seconds to throw out not to swallow The
Anesthesiologists Position was arranged for both anesthesiologist
to stand at the head of the patient with the assistant anesthetist
stood on the left and the FOB intubating anesthetist will stand to
Patients were Pre-oxygenated for 5 minutes with normal tidal
breathes of 6.0 L/min 100% O2 via tightly fitting face mask- Magill
circuit (Mapleson A) with reservoir bag 2liters [6,7]. Anesthesia
induction using single IV bolus of fentanyl (1 μcg/kg) after which
sevoflurane inhalational induction (6-8%) was started using the
semi-closed ventilator circuit carried over 100% O2 of 6.0 L/min
till loss of consciousness with maintained respiratory drive occur.
(Anesthesia depth and Loss of consciousness confirmed by mask
end-tidal concentrations of sevoflurane just before successful
tracheal intubations >4% , and loss of the lid-lash reflex) .
Fiberoptic Intubation was conducted according each group
as follow: Control Group(F) Done by two anesthetists; the 1st
anesthetist (assistant) inserted sterile airway with head tilt- chin
lift- jaw thrust and the 2nd anesthetist 2nd anesthetist (five years
expert in FOB intubation with experience of successful 400 FOB
oral intubations) did oral FVFOB along the FOB specific airway, jaw
thrust was performed by placing the fingers behind the posterior
ramus of the mandible, with the thrust directed upwards and the
thumbs caudally. Study Group (MF) Done by two anesthetists; the
1st anesthetist (assistant) did Macintosh Laryngoscope laryngeal
exposure with size III blade for all cases (size II blade to be ready
in case needed for very short thyromental distance), the 2nd
anesthetist ( five years expert in FOB intubation with experience
of successful 400 FOB oral intubations) did oral FVFOB by
introducing the FOB to the right of the pre-inserted Macintosh
laryngoscope blade and directed centrally targeting the laryngeal
After visualizing the glottis straight ahead in both groups;
another topicalization sitting spray-as-you-go technique  of
1mg/kg lidocaine 2% via the FOB working channel to directly
administer local anesthetic to supraglottic and glottic structures
during advancement of the instrument, then a propofol bolus dose
of 1mg/kg to ensure complete suppression of the airway reflexes
and prevent any complications, then Fine adjustments with slight
motion of the wrist and elevation or depression of the tip using
the angulations (thumb) control lever aid in steering the scope
toward the vocal cords, FVFOB was then introduced through the
vocal cords visualizing the tracheal rings, to the level of the midtrachea
(optimal tube positioning 2-3 cm above the carina), then
tracheal tube was introduced over the FVFOB shaft into the trachea
(Ett should be turned gently counterclockwise with retraction and
then re-advanced if resistance is encountered during placement to
decrease the occurrence of laryngeal trauma .
Correct Ett placement was confirmed by FVFOB view of
carina and tracheal rings together with the Capnogram waveform
. The FVFOB was then withdrawn as the tube is held in place
by hand, After ETT placement and securing a bolus dose of 0.5
mg/kg Rocuronium muscle relaxant will be given for operative
relaxation issue. Primary and secondary outcome variables data
were collected. Technique Failure and complication management
according to ABCD as follow
a. Failed FOB intubation cases were managed as follow:
(failed intubation was defined as); Case exposed to 3 trials of
FOB intubation with insertion time (IT) 90 second for each
trial and couldn’t be intubated. Any complication leads to
failed intubation 3 trials to be reported and excluded from the
study and replaced by another case.
b. Prevention: Sufficient inhalational anesthetic depth
(MAC>1.5) to ensure airway reflexes suppression.
c. Management: I) Removing the cause: Any triggering
stimulation secretion suction ensuring a clear larynx. II) Use
Glidoscope as a standby intubation instrument in emergency
situation . If a Glidoscope also failed the decision is to
cancel surgery and to awake the patient . III)- According
to Adult Difficult Airway Society 2015 guidelines 
sequence of events was arranged in three planes (A, B, C) if
failed intubation encountered during the study
d. Plan A: Maintaining oxygenation via Supraglottic Airway
Devise (SAD) insertion either to wake the patient or to
intubate through SAD or to continue with the SAD or if CICO
(can’t intubate can’t oxygenate) go for plan C
e. Plan B: Face mask ventilation if ventilating wakes the
patient, can’t intubate can’t oxygenate (CICO) go for plan C.
f. Plan C: Emergency front of the neck access
Cases with Laryngospasm management  with
hydrocortisone 1mg/kg bolus, Application of CPAP with 100%
oxygen. I.V. propofol (0.5 mg kg) increments if not effective
Succinylcholine1mg/kg to be given. Cases with Bronchospasm
management  increase anesthesia depth, if ventilation
through ETT difficult/impossible, check tube position and exclude
blocked/misplaced tube, in non-intubated patients exclude
laryngospasm and consider aspiration. Drug therapy Magnesium
sulphate 50mg.kg-1 IV over 20min (max 2g), Hydrocortisone:
200mg IV 6 hourly Ketamine: Bolus 10-20mg. Infusion 1-3mg.kg,
in extremis: Epinephrine (Adrenaline) Nebulized: 5mls 1:1000 or
Intravenous 10mcg (0.1ml 1:10,000) to 100mcg (1ml 1:10,000)
titrated to response.
Cases with Apnea &desaturation Apnea was defined as
the cessation of spontaneous ventilation associated with an
absence of expired carbon dioxide (by a side stream carbon
dioxide analyzer) lasting >10seconds [10,11] Desaturation limit
≤ 90% arterial pulse oximeter reading. Management adequate
pulmonary ventilation was ensured through a facial mask (handbag,
ventilation) then according to adult difficult airway society
2015 guidelines 
Endotracheal intubation insertion time (EttIT), defined as
Time from introduction of the tip of the FOB laryngoscope till
carbon dioxide appeared on the capnography after intubation
with ETT in the laryngeal inlet down to the trachea.
Intubating conditions scoring: each parameter was scored as
follow for statistical analyses
a. Modified Mallampati = (III=1, IV=2).
b. Thyromental distance≤ 5cm (in centimeters by the
original patient measurement)
c. Jaw relaxation = (Relaxed = 0, not fully =1, poor = 2).
d. Resistance to FOI (no= 0, slight =1, active = 2).
e. Vocal cord position (Abducted=0, Intermediate=1,
f. Neck movements during ETT positioning or cuff
inflation= (no=0, slight=1 vigorous=2) .
Intubation technique conditions
Trials success rate = number of patients intubated within
the 1st 90 seconds in each group. 2-Failed ETT intubation > 270
seconds (3 successive FOB intubation separate trials 90 seconds
each on 3 time separated by oxygenation).
Hemodynamics changes after ETT insertion
Systolic Noninvasive Blood Pressure (SNIBP) measured Every
1 min, Heart Rate (HR) both SNIBP and HR were recorded basal
and just after ETT in the trachea, and EtCO2 when detected to
be recorded. Desaturation ≤90%. (Yes=1, No=0). End tidal Co2
(EtCO2) after intubation.
Statistical Data management
The Sample size was calculated Using G Power program.
Based on pilot study of 40 patients 20 for each group (as no
previous study compared combined use of FVFOB and Macintosh
laryngoscope in PDEtt cases.) yielding an, Effect size d=0.6676508,
α error= 0.05, Power (1-β error) =0.85.
Result in Sample size lower limit of 42 for each group which
hence 50 patients were assigned for each group with Total sample
size=100 patients and consequently 130 patients were enrolled to
compensate dropped cases.
Data were analyzed using SPSS software (version 16.0 for
Windows; SPSS Inc., Chicago, IL, USA). The data was tested for
normality using the Shapiro test and Kolmogorov-Smirnov test.
Descriptive data were calculated for all variables (qualitative)
that were presented as frequencies and percentages, the analytic
data was expressed as means and standard deviation (M±SD),
median and range (M&R). Independent sample-t-test was used for
comparing the continuous parametric variables and, Chi-square
test or Fisher’s exact test (for categorical data). The statistical
significance level was set at ≤ 0.05 and highly statistical level was
set at ≤ 0.01.
In this present study, intubation technique conditions (Table
1) showed significant decrease in EET insertion time in Group MF
(32.04± 7.8 seconds) compared to Group F (68.6 ± 12.24 seconds)
P<0.001, significant increase in 1st trial success in Group MF
49 (98%) compared to Group F 41 (82%) P=0.008. Intubating
conditions scoring (Table 2) showed no significant difference in
between groups as regard jaw relaxation, neck movement, and
air way resistance to ETT, vocal Cord position, and ETT induced
coughing. Hemodynamically (Table 3) there were significant
increase in NISBP&HR readings just after ETT in comparison to
the basal reading inside each group, Also significant decrease in
post Ett insertion EtCo2 in group MF compared to group F with no
significant difference as regard desaturation during Ett and EtCo2.
Patient demographics (Table 4) showed no significant difference
in between groups including Modified Mallampati score, and
Thyromental distance. Failed FOB intubation cases (8 cases for
both groups), cases with side effects and complications such as
desaturation (3 cases for both groups) were managed according
to (ABCD) discussed before in the methodology.
Data are presented in mean ± SD, or number (%), * = Significant
value p≤ 0.05, and median &range. (*) There is significant table shows
significant decrease in ETT insertion time and significant increase in 1st
trial success in group MF in comparison to group F.
Data are presented in mean ± (SD), or number (%), this table shows
no significant differences in between both groups as regard intubation
conditions scoring enumerated in the table.
Data are presented in (Mean ± SD), or number (%).This table
shows significant increase # in both systolic SNIBP and after intubation
values heart rate in comparison to basal readings inside each group.
Also significant decrease in post Ett insertion EtCo2 in group MF
compared to group F * Significant difference, p. value ≤ 0.05.
Data are presented in mean ± SD, or number (%), this table shows
no significant differences in between both groups as regard patients
demographic variables enumerated in the table.
No previous clinical study analyzed the effect of Combined
Macintosh laryngoscope with Flexible FOB in PDEtt airways, so
that we carried out a pilot study to calculate a statistically effective
sample size. In this present study, we hypothesized that combined
use of Macintosh laryngoscope with the FVFOB could be feasible
and safe technique that facilitate the FOB intubation function in
Difficult airway prediction and the device used instead of
Macintosh laryngoscope still a critical issue, despite the fact that
el Ganzouri risk index high accuracy in PDEtt and the advanced
video laryngoscopy technology both improved laryngeal
structures visualization . Difficult Airway Society 2015 
for management of PDEtt in adults advised Video laryngoscope as
the first choice . Flexible FOB laryngoscope remains the gold
standard tool in intubating predicted and unpredicted difficult
airway situations. Incidence of difficulty in passing a tracheal tube
over an orally inserted FOB varies considerably between studies,
so that the need to improve Feasibility and success rate of flexible
FOB stay challenging all the time.
The present study showed significant decrease (near 50%
reduction) in EET insertion time in Group MF (32.04± 7.8 seconds)
compared to Group F (68.6 ± 12.24) P<0.001, significant increase
in 1st trial success in Group MF 49 (98%) compared to Group
F 41 (82%) P=0.008 higher than previous studies [18,19] done
on flexible FOB laryngoscope alone, this can be explained by the
fact that Macintosh blade prevented the backward displacement
Oropharyngeal structures such as the tongue, soft palate and
epiglottis which may close the airway during FOB intubation.
Previous study on FOB alone in difficult intubation patients
such as, Calogero et al. (2015)  reported that FOB 1st trial
success of (92.6%) in PDEtt patients, Salma et al. 2015 
reported a FOB success rate of (73.3%) and EttIT (62.97 ± 37.5
seconds), meanwhile in our present study adding Macintosh
blade before FOB has lowered the tracheal tube insertion time
down to 32.04± 7.8 seconds (nearly 50% less) and increased
the intubation success rate Group MF 98% in comparison to
the previous studies[3,20] results indicating great feasibility of
combined use of FOB and Macintosh laryngoscope during difficult
As regard comparison to other airway devices combinations
with FOB: All the previous studies were done for non-difficult
airway patients, except Aziz et al.  who documented 93% first
attempt success rate in predicted difficult airway, a result lower
than our result (98% 1st attempt success rate), Moore et al. 
showed a high success rate (96%) of the same intubation technique
in morbidly obese patients. Gupta et al. , documented that,
during intubating highly seated larynx the Combined Flexible
FOB simultaneously with C-MAC VLS enhanced visualization of
intubation field and decreased chances of trauma to delicate soft
tissue structures. Our opinion is that all operative theaters all over
the world may not have both C-MAC and FOB laryngoscope at the
same time but Macintosh laryngoscope is popular present every
were, cheap, and widely used as primitive goldstone tool for classic
Ett that guarantee airway opening with wide space view prior
the entrance of the flexible FOB laryngoscope which is also the
goldstone basic tool for predicted difficult endotracheal intubation
which is the field of our study. All the previous mentioned studies
airway intubating techniques were comparable to our technique
results regarding tracheal intubation success rate and insertion
The reliability of rigid video laryngoscopes in difficult
airways, Niforopoulou et al.  postulated that despite clear
glottis visualization, tracheal insertion of the Ett with video
laryngoscopes may fail, in our present study combined FVFOB
(which guarantee Ett advancement over its shaft with the aid
of the FVFOB tip upward movement ability to reach the highly
seated larynx) with Macintosh laryngoscope blade pre-exposure
(which could guarantee better airway opening and rapid glottis
access during Ett insertion).
Inhalational anesthesia with airway LA topicalization and
fentanyl analgesia without IV muscle relaxants, maintain the
respiratory drive without exposing the patient to the stress of
the awake airway instrumentation despite that, still has the
drawback of unpredictable effect on the patient respiratory drive
when used in not enough or more than enough doses, despite
that we can control the dose, concentration, and delivery rate
of the inhalational drug guided by the end tidal sevoflurane
concentration if bispectral index is not available. In line with our
anesthesia induction technique, Tan et al.  documented that
sevoflurane combination with remifentanil anesthesia induction
for FOB intubation, provided fast induction and good intubation
condition with stable hemodynamics.
Long time back, Stacey et al.  used FOB with Macintosh
laryngoscope but in normal- non-difficult airway patients and
found a clear airway in 92% of the patients at the level of the
larynx. On the other hand, Johnson et al.  published a case
report advised that Macintosh laryngoscope could help during
FOB intubation during difficult airway conditions. Up till now this
is the only clinical research studied the value of combine FOI with
Macintosh laryngoscope in difficult intubation predicted airway.
FOB intubation has three steps; visualization of the glottis
with FOB, passing the FOB through the glottis into trachea till
carina, and lastly railroading the Ett over the FOB into the trachea
. Backward displacement Oropharyngeal structures may
close the airway adding difficulties during FOB under general
anesthesia. Using airways, lingual traction and jaw thrust are
the maneuvers that may help to overcome this problem. Difficult
Airway intubation tool that guarantee the best airway opening
simultaneously with glottis opening easy rapid access would be
the most ideal, and this could never be achieved by using single
Clinical implications supporting the hypothesis: A comparable
application to our technique is that of the Sensa Scope®, a hybrid
intubation endoscope which guarantee safety, easy-to-handle,
and effective video-assisted intubation. Has combined rigid
and flexible parts. Its S-shaped rigid segment enables a very
intuitive handling by one hand only, thus leaving the left hand
free to operate a conventional laryngoscope. The device tip can
be controlled via a steering handle same as FOB. Its Ett insertion
success rate is 97% nearly similar to our intubation success rate
in this present study (98%) .
a. Patients with Cervical spine instability or trauma may not
benefit from this technique as it does not guarantee cervical
vertebra immobility due to upward curved Macintosh blade,
in opposition, Yumul et al.  advised that C-MAC is superior
to fiberoptic flexible laryngoscope as regard the time required
to obtain glottic view and successful placement of the tracheal
tube in patients requiring cervical spine immobilization.
b. No available Bi-spectral index in the hospital (anesthesia
depth detector) so we used end tidal sevoflurane concentration
and lid lash reflex.
c. General anesthesia induction technique in our study
utilizing inhalational sevoflurane avoiding IV muscle
relaxation still has the drawback of unpredictable effect on the
patient respiratory drive when used in not enough or more
than enough doses even so still in hand as we can control the
dose, concentration, and delivery rate of the inhalational drug
using end tidal sevoflurane concentration >5.5% and lid lash
reflex if bispectrality index is not available.
d. Still we can’t guarantee 100% difficult airway prediction
while using two or three scoring airway systems, so we used
an internal scoring system NT-MMS and an external scoring
system thyromental distance to predict as far as possible the
difficult airways to be included in our study.
e. This muscle relaxant free technique may be of less
comfortable to the intubator but provided a totally accepted
intubation circumstances, patient safety depending on the
maintained respiratory derive all over the technique.
The combined use of Macintosh laryngoscope with the flexible
FOB in predicted difficult endotracheal intubation conditions
provides significant decrease in endotracheal tube insertion time
(near 50% reduction), significant increase in 1st endotracheal
intubation trial success rate, acceptable intubating conditions and
hemodynamic stability compared to flexible FOB alone.