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3 2 2 A N NA LS O F E M E RG E NC Y M E DI C IN E 4 1 :3 MARCH 2003
A I R W A Y / O R I G I N A L R E S E A R C H
Richard M. Levitan, MD
C. Crawford Mechem, MD
E. Andrew Ochroch, MD
Frances S. Shofer, PhD
Judd E. Hollander, MD
From the Departments ofEmergency Medicine (Levitan,Mechem, Shofer, Hollander)and Anesthesiology (Ochroch),University of PennsylvaniaSchool of Medicine, Philadel-
phia, PA.
Copyright 2003 by the American
College of Emergency Physicians.
0196-0644/2003/$30.00 + 0
doi:10.1067/mem.2003.87
Head-Elevated Laryngoscopy Position:Improving Laryngeal Exposure DuringLaryngoscopy by Increasing Head Elevation
See editorial, p. 338.
Study objective: The objective of this study was to determine the effect of increas-
ing head elevation and neck flexion on the quality of laryngeal view during laryn-
goscopy.
Methods: Laryngoscopy with a straight blade was performed on 7 fresh human
cadavers. Laryngeal views were recorded with the direct laryngoscopy video system,
and the laryngoscopy angle was measured throughout the procedure with an angle
finder attached to the handle of the laryngoscope. Each cadaver had laryngoscopy
initiated with the head lying flat on the table and with atlanto-occipital extension. The
head was then progressively elevated as much as possible (the head-elevated laryn-
goscopy position), increasing neck flexion and the laryngoscopy angle. Three physi-
cians blinded to the laryngoscopy angle graded the quality of laryngeal view using
the percentage of glottic opening (POGO) score.
Results: The laryngoscopy angle ranged from a mean of 328 (1 SD) with the head
flat on the table to a mean of 678 with the head-elevated laryngoscopy position.
The mean midposition laryngoscopy angle was 496. Comparing the 3 positions,
mean POGO scores1 SD significantly increased from 31%10% (flat position) to
64%12% (midposition) to 87%13% (head-elevated laryngoscopy position). Both the
midposition and the head-elevated laryngoscopy position compared with the flat
position were statistically significant at a Pvalue of less than .0001. The midposition
also differed significantly from the head-elevated laryngoscopy position (P
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I N T R O D U C T I O N
The importance of proper head and neck positioning
for optimizing laryngeal view during laryngoscopy has
been recognized since the procedure was first described
by Kirstein in 1895.1 Reference textbooks routinely
emphasize slight elevation of the head, extreme atlanto-
occipital extension, and lifting the handle of the laryn-
goscope in a 45direction.2-4
Direct laryngoscopy is the mainstay of emergency air-
way management, and despite the proliferation of diffi-
cult airway devices, alternative methods of intubation
are used extremely infrequently in all settings.5-12
Whether in the emergency department or in the operat-
ing room, there is a large discrepancy between the inci-
dence of difficult laryngoscopy (ie, multiple attempts or
poor laryngeal view), which ranges from 5% and 18%,
and the rate of failed laryngoscopy, which ranges from
less than 0.4% in the ED to 0.05% in the operating
room.5-13 In most instances, difficult laryngoscopy cor-
relates with poor laryngeal exposure.14,15 A study of
nearly 1,200 cases in the operating room identified
patient repositioning among the most common means of
facilitating intubation after an initial failed laryngoscopy
but did not define specific positioning changes.11
The assumptions regarding optimal positioning for
laryngoscopy have historically received little scientific
scrutiny.16,17 Two recent studies have questioned
standard practice regarding head and neck positioning
but seemingly came to different conclusions, with one
suggesting that increasing neck flexion was beneficial,
and the other concluding there was little benefit to mild
head elevation (and neck flexion) over simple exten-
sion.16,17 Neither of these studies used direct laryn-
goscopy imaging to dynamically record laryngeal view
and instead relied on estimations of transiently ob-
served laryngeal view at different positions, each using
a nonvalidated system of grading laryngeal view. Each
also had other issues that potentially limit the value of
their conclusions. One study used a curved blade, intro-
ducing the significant (and unmeasured) variable of
how the tip of the blade interacts with the hyoepiglottic
ligament and vallecula because minor changes in force
and direction at this location can markedly alter laryn-
geal exposure. The other study did not standardize
positioning through measurements between patients or
in any way measure head elevation or laryngoscopy
angle in the different positions.
The authors prior research has combined the use of
the direct laryngoscopy video system with a validated
means of assessing recorded laryngeal images (ie, the
percentage of glottic opening [POGO] score).18-24
Through prior video recordings of laryngoscopy and
our own clinical practice, we had anecdotal evidence
suggesting that increasing head elevation was a simple,
effective, and easily applied means of improving laryn-
geal exposure.
This study was designed to apply laryngeal imaging
and POGO scoring to objectively assess the effect of
dynamically increasing head elevation and associated
neck flexion on the quality of laryngeal view. Quanti-
fying the amount of head elevation is difficult to dy-
namically measure, and a specific amount of head eleva-
tion can have greater or less effect on resultant neck
flexion depending on a patients body habitus. Lifting
the patients head, however, also changes the directional
force along the laryngoscope handle, as well as the oper-
ators angle of view down the lumen of the blade. This
laryngoscopy angle can be readily measured with an
angle finder and can serve as a means of quantifying the
change in position resulting from head elevation.
M A T E R I A L S A N D M E T H O D S
The study was performed on 7 fresh human cadavers, 4
male and 3 female, at the medical school morgue at the
University of Pennsylvania School of Medicine. Laryngo-
scopy was performed with a Henderson laryngoscope
blade (Karl Storz Endoscopy, Inc., Culver City, CA).25
Like the Miller blade, the Henderson blade is a straight
blade with a narrow flange height, but it has a slightly
different-shaped lumen and a completely straight visi-
ble distal tip (Figure 1).26 The upturned tip of the
Miller blade or any curved blade design could poten-
tially cause a discrepancy between the laryngoscopy
angle (as measured and defined below) and the opera-
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was affixed on the handle, the resultant angle on the
angle finder correlated with the angle of the laryngo-
scope blade relative to the patient. For example, if the
blade was oriented parallel to both the floor and the
long axis of the patient (with the handle pointing
straight up toward the ceiling), this would represent a
laryngoscopy angle of 0. If the blade was positioned
pointing vertically downward and perpendicular to
both the floor and the long axis of the patient (with the
handle now parallel to the patient), this would repre-
sent a laryngoscopy angle of 90.
Laryngoscopy was initiated with the head flat on the
table, with the occiput resting on the table and the head
extended at the atlanto-occipital joint (Figure 2). The
head was then progressively lifted from the table to a
height as high as possible (by the laryngoscopists right
hand), which simultaneously increased the degree of
neck flexion and the laryngoscopy angle displayed on
the angle finder (Figure 3).
tors actual angle of laryngeal view down the lumen of
the blade.27
The laryngoscopy angle was measured with a com-
mercially available angle finder obtained at a local hard-
ware store (Home Depot, Inc., King of Prussia, PA),
which was attached lengthwise to the laryngoscope
handle with plastic cable ties (Figures 2 and 3). Because
of the perpendicular position of the straight Henderson
blade to the handle and the manner that the angle finder
Figure 1.The Henderson straight laryngoscope blade (Karl StorzEndoscopy, Inc.). The blade is straight along its entire length,has a relatively small flange height, and has a visible distal
tip.
Figure 2.Laryngoscopy with the head flat on the table with an angle
finder attached lengthwise to the laryngoscope handle. Thelaryngoscope angle is approximately 40. Inset is the view ofthe larynx as displayed by the direct laryngoscopy video sys-tem worn by the laryngoscopist. The POGO score is approxi-mately 30%.
Figure 3.Laryngoscopy with the head fully elevated (ie, the head-ele-vated laryngoscopy position). The laryngoscopist is using theright hand to elevate the head. The laryngoscopy angle isapproximately 80, and the POGO score in the inset isapproximately 90%.
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The laryngeal view was imaged continuously by
using the Airway Cam direct laryngoscopy video sys-
tem (Airway Cam Technologies, Inc., Wayne, PA).19
The direct laryngoscopy video system uses a head-
mounted miniature video camera that is aligned with
the line of sight of the laryngoscopists dominant pupil.
Video recording was done with a Sony GVD-300 (Sony
Corporation, Tokyo, Japan) digital videocassette re-
corder, capturing 30 frames per second. In addition to
the video recordings made with the direct laryngo-
scopy video system, a Sony DCR-PC1 (Sony Corpora-
tion) digital camcorder was simultaneously operated
by an assistant to record the laryngoscopy angle as seen
from a position perpendicular to the patient. The video
recordings of laryngeal view and the angle finder were
synchronized and superimposed with Adobe Premier
6.0 video editing software (Adobe Systems, Inc., Seattle,
WA; Figures 2 and 3).
The synchronized video clips were reviewed by 1 of
the authors (RML), and laryngoscopy angles were
recorded in 3 positions on each patient: head flat on the
table, full elevation, and a midposition that was selected
by observing the range of head elevation on the video-
tapes for each cadaver. Full elevation position was the
greatest amount of head elevation and greatest amount
of neck flexion achievable in each cadaver. The laryn-
geal views at the 3 positions were graded by 2 emergency
physicians (CCM, JEH) and 1 anesthesiologist (EAO)
using the POGO score.20,21The 3 physicians were
blinded to the laryngoscopy angle associated with each
laryngeal view, as well as to each others POGO scores.
The POGO score describes how much of the glottic
opening is visible; a 100% POGO score includes visual-
ization of the entire glottic opening from the anterior
commissure of the vocal cords to the interarytenoid
notch (Figure 4). A POGO score of 0% corresponds
with no visualization of laryngeal structures (ie, epi-
glottis or tongue-only views). The POGO score has
been shown to have excellent intrarater and interrater
reliability and to correlate with success of intubation, as
well as with need for rescue intubation devices.20,21,24
POGO scores were assigned to each cadaver at 3 posi-
tions from the videotape recordings: head flat on the
table, midposition, and full elevation. A 3-way analysis
of variance in repeated measures (1 observation per
cell) was used where the 2 repeated measures were rater
Figure 4.POGO score. Full visualization of the glottic opening fromthe anterior commissure to the interarytenoid notch equals100%. When no portion of the glottis is seen (ie, epiglottis ortongue-only views), the POGO score equals 0%. POGO scor-ing does not distinguish between these 2 situations.
Figure 5.Mean laryngoscopy angles at 3 different head positions in 7
cadavers. The midposition was determined by reviewingvideotaped images of laryngoscopy from a perspective per-pendicular to the patient. Bars represent mean1 SD.
100
80
60
40
20
0
Angleo
flarangoscopy
Head flat Mid-position Full elevation
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Comparing the 3 positions, POGO scores signifi-
cantly increased from a meanSD of 31%10% (flat
position) to 64%12% (midposition) to 87%13%
(head-elevated laryngoscopy position; Figure 6). Both
the midposition and the head-elevated laryngoscopy
position compared with the flat position were statisti-
cally significant at a P value of less than .0001. The mid-
position also differed significantly from the head-ele-
vated laryngoscopy position (P
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Hochman et al16 studied the effects of straight laryn-
goscope blade size, as well as head and neck positioning,
on the force required for optimal laryngeal exposure.
They concluded that increasing head elevation and
neck flexion increased the incidence of full laryngeal
exposure with less required force. Hochman et al char-
acterized the position that optimized laryngeal expo-
sure as flexion-flexion, referring to both atlanto-
occipital flexion and cervicothoracic vertebrae flexion.
An analysis of their photographs, however, suggests
that the atlanto-occipital joint is not truly flexed (ie, the
laryngoscopy angle is not >90). In our study, the laryn-
goscopy angle was always less than 90, even at full
head elevation. For this reason and also because head
elevated is a simpler term to describe the primary
movement, we believe that head-elevated laryn-
goscopy position is a better term for this type of posi-
tioning than flexion-flexion.
Our study has several limitations; we had a small
sample size, and all laryngoscopies were performed by
one laryngoscopist. We only studied laryngoscopy with
one blade design, and our results might not be transfer-
able to more commonly used blades. Although we be-
lieve that fresh cadavers approximate the mechanical
response to laryngoscopy in living patients, there might
have been unrecognized different responses to tongue
compression or other aspects of laryngoscopy that
might have affected our results. There is stress relax-
ation of the pharyngeal tissues and tongue during
laryngoscopy in live patients, and this might be differ-
ent than the response in cadavers.30We performed
laryngoscopy repeatedly to minimize the effect of
sequence on the results and did not observe significant
differences between laryngeal views at various posi-
tions going up versus going down, but this was not
specifically measured.
Our results focused on increasing glottic exposure,
but full exposure of the glottis is not required for intu-
bation, and the relevance of this degree of exposure for
intubation, particularly anterior glottic exposure, is
unknown. A prior study of nearly 6,000 patients found
that increasing POGO scores by greater than 25% is
clinically significant and that there is correlation be-
tween decreased POGO scores and the number of intu-
bation attempts, as well as the need for rescue intuba-
tion devices.24 It is unclear from this limited study how
Figure 7.Drawings of proper positioning. A, Normal recumbency onthe table with a pillow supporting the head. The larynx canbe directly examined in this position, but a better position isobtainable. B, Head is raised to proper position with the head
flexed. Muscles of the front of neck are relaxed, and exposureof the larynx is thus rendered easier. For most endoscopicwork, a certain amount of extension is desired, but the eleva-tion is the important thing. C, With the neck being main-tained in position B, the desired amount of extension of thehead is obtained by a movement limited to the occipito-atloidarticulation by the assistants hand placed, as shown by the
arrow (in B). Overextension is to be avoided. D, Faulty posi-tion. Reprinted with permission from Jackson C, Jackson CL.Bronchoscopy, Esophagoscopy and Gastroscopy: AManual of Peroral Endoscopy and Laryngeal Surgery.Philadelphia, PA: WB Saunders Company; 1934:85-105.38
Normal recumbency
Raised flexed
Raised, extendedCorrect
Faulty
HBHB
Occipito-alloidjoint
Chest heavedSpine arched
A
B
C
D
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issues facing patients who require emergency intuba-
tion.5,36We believe that the easiest, fastest, and most
effective modification to improve view is external
laryngeal manipulation.22 For patients in whom neck
movement is not contraindicated, the head-elevated
laryngoscopy position is a second modification that can
be easily performed during initial laryngoscopy efforts
if the laryngeal view remains inadequate. The simplest
way to achieve the head-elevated laryngoscopy position
is for the laryngoscopist to directly lift the patients head
with his or her right hand. The right hand must be re-
leased to pass the tracheal tube, but for patients of normal
dimensions, suspending the head with the laryngo-
scope only for a brief moment is not difficult. In situ-
ations of extreme obesity, effective head elevation can-
effective the head-elevated laryngoscopy position
would be in instances when it is truly needed (ie, when
initial POGO scores are 0% or otherwise very low). We
believe that the technique improves the view across the
entire spectrum of laryngeal visualization, but we did
not have enough cases of poor initial view to prove this
in the present study.
Finally, although we believe that the head-elevated
laryngoscopy position improves laryngeal view, the
study only used cadavers, and the safety of this tech-
nique in living patients was not assessed. Obviously,
aggressive manipulation of the neck, even the standard
intubating position, is contraindicated in instances of
potential or existent cervical spine injury or pathol-
ogy.31,32
Ironically, there has been one case report of emer-
gency intubation with extreme flexion positioning on a
patient with anklylosing spondylitis and fixed flexion
of the cervical spine.33 Mindful of the patients prepro-
cedure cervical spine position, the clinician lowered the
head of the bed into the Trendelenburg position and
supported the patients head with a pillow; the resultant
laryngoscopy angle was almost 90, and the vocal cords
were completely exposed.33
There is evidence from radiographic studies and
clinical reports that increasing head elevation might be
safer than increasing atlanto-occipital extension in sit-
uations of poor laryngeal exposure. Neurologic injury
related to overaggressive head and neck extension dur-
ing laryngoscopy has been reported, specifically central
cord syndrome.34 Radiographic analysis has shown that
extension from C1-C4 is near maximal in the standard
intubating position, when the lower spine is relatively
straight.35 For this reason, it has been suggested that if
standard positioning is to be modified, any additional
extension should be avoided, and instead additional
flexion (ie, head elevation) should be attempted.35
Modifications of laryngoscopy techniques that can
increase first-pass intubation success are critical in the
emergency setting. Simple maneuvers that can improve
laryngeal view without requiring special tools, exten-
sive training, or expense are particularly valuable given
the reliance in the ED on laryngoscopy and the clinical
Figure 8.Achieving the head-elevated laryngoscopy position in a mor-bidly obese patient requires massive amounts of supportunder the head and shoulders. Used by permission from
Airway Cam Technologies, Inc., Wayne, PA.
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not be done singlehandedly by the laryngoscopist and
instead requires massive amounts of support placed
under the shoulders, as well as the head (Figure 8).2,37
Alternatively, as demonstrated by Hochman et al,16 the
patients head can be supported by the laryngoscopists
torso leaning inward, but with a standard stretcher, this
requires the patients head to be positioned at the ex-
treme edge of the bed. The head-elevated laryngoscopy
position can also be easily achieved with an assistant,
which was the technique advocated by Jackson and
Jackson.38We believe this is best accomplished by the
assistant being at a position near the head of the bed,
crouching down until his or her shoulders are at the
level of the patient, and then lifting with both arms to
support the patients head and shoulders.
This study demonstrates significantly improved
POGO scores on fresh cadavers by using the head-
elevated laryngoscopy position. We have had anecdotal
success with the head-elevated laryngoscopy position
in our ED during difficult laryngoscopies and believe
the technique warrants prospective study with laryngo-
scopic imaging in living patients. Further study is
needed to define its utility in cases of very poor initial
laryngeal view, as well as to prove its safety and efficacy
in the emergency setting.
We thank J. Dwayne Hallman, BS, Anatomy Morgue Technician,
and Dr. Paul Teresi, MD, Anatomy Morgue Director, each of the
University of Pennsylvania School of Medicine, for their assistance
with this project. Boaz Rosenblatt, MD, and Nancy Sun, MD, each
assisted with the video recordings.
Author contributions: RML designed the study and performed all the
laryngoscopies. CCM and EAO videotaped and provided assistance
in the cadaver laboratories. CCM, EAO, and JEH performed POGO
scoring of the laryngeal images. JEH and FSS were responsible for
revising the paper, as well as the statistical analysis. RML takes pri-
mary responsibility for the paper as a whole.Received for publication February 22, 2002. Revisions received
August 2, 2002, and August 20, 2002. Accepted for publication
August 26, 2002.
The authors report this study did not receive any outside funding or
support.
Dr. Levitan is the patent holder on the direct laryngoscopy video
system used for videographic imaging of laryngoscopy in this study.
He is also a principal owner of Airway Cam Technologies, Inc.,
Wayne, PA, which produces and sells the imaging system.
Reprints not available from the authors.
Address for correspondence: Richard M. Levitan, MD, Department
of Emergency Medicine, Hospital of the University of Pennsylvania,
3400 Spruce Street, Philadelphia PA 19104; 215-662-7260; E-mail
levitanr@mail.med.upenn.edu.
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