Humming Is as Effective as Valsalva’s Maneuver and Trendelenburg’s Position for Ultrasonographic Visualization of the Jugular Venous System and Common Femoral Veins

Abstract

The purpose of this study is to compare ultrasonographic visualization of the jugular and common femoral veins by using a novel technique (humming) and 2 conventional techniques (Valsalva's maneuver and Trendelenburg's position). The Valsalva's maneuver and Trendelenburg's position are common methods for producing venous distention, aiding ultrasonographically guided identification and cannulation of the jugular and common femoral veins. We hypothesize that humming is as effective as either Valsalva's maneuver or Trendelenburg's position for distention and ultrasonographic visualization of these procedurally important blood vessels. Herein, we investigate a new method of venous distension that may aid in the placement of central venous catheters by ultrasonographic guidance.
Healthy, normal volunteers aged 28 to 67 years were enrolled. Each subject's internal jugular, external jugular, and common femoral veins were measured in cross-section by ultrasonograph during rest (baseline), humming, Valsalva's maneuver, and Trendelenburg's position. Three measurements were recorded per observation in each position. Subjects were used as their own controls, and measurements were normalized to percentage increase in diameter during each maneuver or position for later comparison.
The study population consisted of 7 subjects, with a mean age of 47 years. Cross-sectional area was calculated for each vessel in 3 groups: baseline/control, Valsalva, Trendelenburg, and humming. The mean percentage change (+/-SD) relative to baseline cross-sectional area of the jugular vessels for each subject were external jugular vein: humming 134%+/-25% (95% confidence interval [CI] 124.9% to 146.9%), Valsalva 136%+/-23% (95% CI 121.3% to 147.5%), Trendelenburg 137%+/-32% (95% CI 120.7% to 156.9%); internal jugular vein: humming 137%+/-27% (95% CI 119.4% to 148.2%), Valsalva 139%+/-24% (95% CI 122.4% to 148.7%), Trendelenburg 141%+/-35% (95% CI 116.5% to 156.5%); common femoral vein: humming 131%+/-15% (95% CI 120.4% to 139.1%), Valsalva 139%+/-18% (95% CI 127.9% to 150.4%), Trendelenburg 132%+/-24% (95% CI 113.3% to 142.9%).
All 3 maneuvers distended the external jugular, internal jugular, and common femoral veins compared to baseline. There was no important difference in magnitude of cross-sectional area between any of the 3 maneuvers when compared with one another. Humming shares many physiologic similarities to Valsalva's maneuver and may be more familiar and easier to perform during procedures such as ultrasonographically guided central venous catheter placement and insertion of external jugular intravenous catheters.

Full text

IMAGING/BRIEF RESEARCH REPORT
Humming Is as Effective as Valsalva’s Maneuver and
Trendelenburg’s Position for Ultrasonographic Visualization
of the Jugular Venous System and Common Femoral Veins
Matthew R. Lewin, MD, PhD
John Stein, MD
Ralph Wang, MD
Marsha M. Lee, MD
Martin Kernberg, MD
Milana Boukhman, MD
In-Hei Hahn, MD
Resa E. Lewiss, MD
From the Division of Emergency Medicine (Lewin, Stein, Wang, Kernberg, Boukhman) and
Department of Pediatrics (Lee), University of California, San Francisco, CA; the Department of
Emergency Medicine, St. Lukes–Roosevelt Hospital (Hahn, Lewiss), New York, NY; and the
Department of Radiology, Eastern Maine Medical Center, Bangor, ME (Kernberg).
Study objective: The purpose of this study is to compare ultrasonographic visualization of the jugular
and common femoral veins by using a novel technique (humming) and 2 conventional techniques
(Valsalva’s maneuver and Trendelenburg’s position). The Valsalva’s maneuver and Trendelenburg’s
position are common methods for producing venous distention, aiding ultrasonographically guided
identification and cannulation of the jugular and common femoral veins. We hypothesize that
humming is as effective as either Valsalva’s maneuver or Trendelenburg’s position for distention and
ultrasonographic visualization of these procedurally important blood vessels. Herein, we investigate a
new method of venous distension that may aid in the placement of central venous catheters by
ultrasonographic guidance.
Methods: Healthy, normal volunteers aged 28 to 67 years were enrolled. Each subject’s internal
jugular, external jugular, and common femoral veins were measured in cross-section by
ultrasonograph during rest (baseline), humming, Valsalva’s maneuver, and Trendelenburg’s position.
Three measurements were recorded per observation in each position. Subjects were used as their
own controls, and measurements were normalized to percentage increase in diameter during each
maneuver or position for later comparison.
Results: The study population consisted of 7 subjects, with a mean age of 47 years. Cross-sectional
area was calculated for each vessel in 3 groups: baseline/control, Valsalva, Trendelenburg, and
humming. The mean percentage change (!SD) relative to baseline cross-sectional area of the jugular
vessels for each subject were external jugular vein: humming 134%!25% (95% confidence interval [CI]
124.9% to 146.9%), Valsalva 136%!23% (95% CI 121.3% to 147.5%), Trendelenburg 137%!32% (95%
CI 120.7% to 156.9%); internal jugular vein: humming 137%!27% (95% CI 119.4% to 148.2%), Valsalva
139%!24% (95% CI 122.4% to 148.7%), Trendelenburg 141%!35% (95% CI 116.5% to 156.5%);
common femoral vein: humming 131%!15% (95% CI 120.4% to 139.1%), Valsalva 139%!18% (95% CI
127.9% to 150.4%), Trendelenburg 132%!24% (95% CI 113.3% to 142.9%).
Conclusion: All 3 maneuvers distended the external jugular, internal jugular, and common femoral
veins compared to baseline. There was no important difference in magnitude of cross-sectional area
between any of the 3 maneuvers when compared with one another. Humming shares many
physiologic similarities to Valsalva’s maneuver and may be more familiar and easier to perform
during procedures such as ultrasonographically guided central venous catheter placement and
insertion of external jugular intravenous catheters. [Ann Emerg Med. 2007;50:73-77.]
0196-0644/$-see front matter
Copyright ©2007 by the American College of Emergency Physicians.
doi:10.1016/j.annemergmed.2007.01.024
Volume ,.:July  Annals of Emergency Medicine 73

INTRODUCTION
Background and Importance
In the United States alone, it is estimated that at least 5
million external jugular vein and central venous catheters are
placed each year in emergency departments (EDs), radiology
and surgical suites, hospital wards, and ICUs.
1,2
When
available, ultrasonographically guided catheter placement is
considered safer than blind anatomically based techniques,
especially in ICU and emergency settings.
3,4
The Valsalva maneuver and Trendelenburg’s position are
common methods for producing venous distension for
ultrasonographic identification and puncture of large central
veins. Though both have been shown to be effective for
producing increases in venous cross-sectional diameter,
5-7
both
positions are not without disadvantages and potential
complications. For example, many dyspneic patients are unable
to tolerate Trendelenburg’s position for sustained periods, and
some patients have syncopal episodes from Valsalva or soil
themselves.
8-10
According to the authors’ experience, it is often
difficult to explain how to performaValsalva maneuver
8,9
but
relatively easy to coax a patient into humming even if physician
and patient do not speak the same language.
A Valsalva maneuver is an attempted exhalation against a
closed glottis or against a closed mouth and nose, as is
experienced in coughing or straining during a bowel movement
or lifting heavy weights. Antonio Maria Valsalva (1666 to
1723), the Italian anatomist, physician, and surgeon, first
described the technique as a means of expressing pus from the
middle ear.
11
Friedrich Trendelenburg (1844 to 1924)
described positioning patients supine with head down and feet
elevated between 30 degrees and 45 degrees during a variety of
surgical procedures.
12
In World War I, Walter Cannon
popularized Trendelenburg’s position as a method of increasing
venous return to the heart, though its value in this regard is now
considered dubious.
13
Understanding the mechanism of humming provides
additional insight into its use as a forced expiration technique.
During humming, the glottis opens and closes intermittently to
help generate sound during the vocal-fold vibratory cycle. The
increased intrathoracic pressure and forced expiration required
by humming resemble those of Valsalva. According to the
observation that opera singers’ external jugular veins distend during
held notes, one of us has frequently asked patients to take a breath
and hum to distend external jugular veins for peripheral
intravenous cannulation. Similarly, this method has been used for
ultrasonographic visualization (but not cannulation) of central veins
for several years by one of the authors (M.R.L.). Our systematic
search of the National Library of Medicine (PubMed) did not
reveal any reports of humming as a method for ultrasonographically
guided visualization of veins commonly accessed for central venous
catheterization. The purpose of this article is to demonstrate the
feasibility of humming as a new maneuver to distend venous targets
for central venous catheterization.
MATERIALS AND METHODS
Study Design, Setting, and Selection of Participants
This was a prospective trial performed on a convenience
sample of healthy volunteers. Four male and 3 female
volunteers, aged 28 to 67 years, were enrolled in the study. For
each volunteer, right and left veins were studied using each
maneuver, for a total of 10 vessels measured in each category
(below).
14
Volunteerswereemergencydepartmentpersonnel,and
the Committee on Human Research agreed that verbal rather than
signed consent was sufficient, given the education level of the
volunteers. Bilateral internal, external jugular, or common femoral
veins were measured in cross-section by ultrasonography during rest
and in the following conditions: “loud” or “deep” humming,
maximum Valsalva while supine, 30-degree Trendelenburg to
measure external jugular and internal jugular veins, and 30-degree
reverse Trendelenburg to measure the femoral veins.
Data Collection and Processing
The skin was marked and rotation angle of the head was
fixed at 45 degrees to ensure reproducibility of probe placement.
For all maneuvers, each vessel was measured 3 times in the
transverse plane perpendicular to the vessel’s longitudinal axis,
with determination of the major (A) and minor (B) axis length
to calculate the elliptical cross-sectional area (Figure 1). The
probe when the measurement was made was placed in the same
manner as if a central venous catheter were being placed (ie, the
apex of the sternocleidomastoid triangle). High-resolution,
real-time, 2-dimensional ultrasonography
14
with gray-scale
imaging was performed for all measurements by using the
Sonosite Titan with standard 7.5-MHz linear probe.
Measurements were made with the electronic caliper function of
Editor’s Capsule Summary
What is already known on this topic
Trendelenburg’s position and the Valsalva maneuver are
often used to facilitate central vein cannulation.
What question this study addressed
To what extent do these techniques and a new
technique—having the patient hum a tune—distend
internal jugular, external jugular, and common femoral
veins as measured by bedside ultrasonography in 7
healthy volunteers?
What this study adds to our knowledge
All 3 maneuvers equally distended these central veins
compared to baseline.
How this might change clinical practice
If the findings of this small study are confirmed in
patients, humming may become a preferred method for
maximizing vein distention because it might be better
tolerated than Trendelenburg’s position and more easily
explained and sustained than the Valsalva maneuver.
Humming and Ultrasonographic Visualization of Jugular Venous System Lewin et al
74 Annals of Emergency Medicine Volume ,.:July 

the Sonosite Titan and recorded on each image. The
measurements were performed by 3 attending emergency
physicians credentialed in ED bedside ultrasonography (one of
3 being fellowship trained: R.W.).
Primary Data Analysis
Mean cross-sectional area was calculated for each vessel (3
measurements for each maneuver) compared to the baseline in
the resting supine position, with the head positioned as
described above. The test response of each maneuver was
expressed as the ratio of the average cross-sectional area evoked
by each maneuver divided by the average baseline cross-sectional
area for each vessel. Data were analyzed with 1-way ANOVA
followed by 2-tailed Newman-Keuls tests (for all between-group
comparisons) or Dunnett’s tests (comparing each group to a single
reference group). Comparisons of only 2 groups were made with t
tests (2-tailed) on the raw data before normalization. The study was
powered according to the prediction that vessels would distend
more than 25% for Valsalva and Trendelenburg’s position, as has
been demonstrated in other studies.
RESULTS
Mean percentage change (!SD) relative to baseline cross-
sectional area of the jugular vessels for each subject were as
follows (Figure 2): external jugular vein: humming 134%!25%
(95% confidence interval [CI] 124.9% to 146.9%), Valsalva
136%!23% (95% CI 121.3% to 147.5%), Trendelenburg
137%!32% (95% CI 120.7% to 156.9%); internal jugular
vein: humming 137%!27% (95% CI 119.4% to 148.2%),
Valsalva 139%!24% (95% CI 122.4% to 148.7%),
Trendelenburg 141%!35% (95% CI 116.5% to 156.5%);
common femoral vein: humming 131%!15% (95% CI
120.4% to 139.1%), Valsalva 139%!18% (95% CI 127.9% to
150.4%), Trendelenburg 132%!24% (95% CI 113.3% to
142.9%). All 3 maneuvers distended the external jugular,
internal jugular, and common femoral veins compared to
baseline (P".05). There was no difference in magnitude of
cross-sectional area between any of the 3 maneuvers when
compared with one another.
LIMITATIONS
All volunteers were health care professionals, so we did not
test comprehension, because of likely biases. Both Valsalva’s
maneuver and humming are effort dependent. However, our
Valsalva and Trendelenburg data are consistent with previously
published data,
5-7
and subjects were instructed to give their
maximum effort during Valsalva’s maneuver, our primary
comparison of interest. Comparisons of central venous pressure
were not made. We do not know the effect this maneuver might
have with regard to protection or promotion from air emboli, a
rare but serious complication of central venous catheter
placement,
15
but awareness of the physiology of air embolism
during venipuncture would be key to prevention when using
this or any standard technique of central venous catheter
placement.
16
Another limitation of this study is that only
healthy volunteers were studied. Our results may not be valid
for patients with poor cardiopulmonary reserve or vascular
collapse. However, we have observed that the percentage of
increase in central venous cross-section is greater in dehydrated
patients (unpublished data), and one of us (M.R.L.) uses the
technique regularly for external jugular venipuncture. Thus, our
study probably underestimates the true increase in cross-
sectional area for any of the 3 positions studied because all
subjects in our study were normal and healthy adults. There are
many readily testable hypotheses that can be generated from our
report.
DISCUSSION
We describe a new but remarkably simple method of distending
and visualizing external, internal jugular, and common femoral
veins. During both maneuvers (humming and Valsalva),
contraction of the thoracic cage and ascension of the diaphragm
cause an increase in intrathoracic pressure and force the air out of
the lungs. This increase in intrathoracic pressure leads to the
Figure 1. Changes in cross-sectional area as demonstrated by 2-dimensional ultrasonography during (A) rest, (B) loud
humming, and (C) maximal Valsalva. Cross-sectional area was determined as a function of the major axes.
Lewin et al Humming and Ultrasonographic Visualization of Jugular Venous System
Volume ,.:July  Annals of Emergency Medicine 75

contraction of the lungs, cardiac chambers, and the superior and
inferior vena cava and to an increase in central venous pressure.
According to measured cross-sectional area, humming is as effective
as Valsalva’s maneuver and Trendelenburg’s position for
visualization of the jugular venous system and common femoral
veins.
In conclusion, humming may be considered a new
technique, among other time-honored, commonly used
maneuvers and positions used to increase the cross-sectional
diameter of the jugular venous system and femoral veins, to aid
ultrasonographically guided central venous visualization. As a
new technique, it is in need of further study before being used
in common practice. Our anecdotal clinical experience is that
the technique is much easier for patients to understand, and it is
more comfortable to hum, especially if there is a language
barrier or painful abdominal, pelvic, musculoskeletal, or motor
neuron pathology (eg, Parkinson’s disease) limiting the ability to
perform Valsalva’s maneuver. We note, without irony, that
patients tend to hum with greater urgency when they feel
pressure from the first needle and, thus, need little prompting to
“hum louder.”
We thank Ms. Sarika Parekh and Drs. Terry Walters, PhD, and
Daniel Musher, MD, for their careful review of the article and
methodology. We also thank members of the San Francisco Opera
for their insights into the physiology of humming.
Supervising editor: David T. Overton, MD, MBA
Author contributions: MRL was responsible for the study
concept and article and study coordination. MRL, JS, RW,
MML conducted data collection. JS conducted protocol
development. RW and MK were responsible for methodology.
MML conducted statistical analysis. MK conducted radiology.
MB, I-HH, and REL were responsible for scholarship and the
pilot study. MRL takes responsibility for the paper as a whole.
Michael L. Callaham, MD, recused himself from the
decisionmaking process for this article.
Funding and support: The authors report this study did not
receive any outside funding or support and there were no
other conflicts of interest to declare. See the Manuscript
Submission agreement form, published each month, for
details of covered relationships.
Publication dates: Received for publication May 18, 2006.
Revision received January 8, 2007. Accepted for publication
January 23, 2007. Available online April 11, 2007.
Reprints not available from the authors.
80
100
120
140
160
180
T
V
H
BB B
T
V
H
V
H
RT
External
Jugular Vein
Internal
Jugular Vein
Common
Femoral Vein
*
*
*
*
*
*
*
*
*
% baseline
Figure 2. Humming is as effective as Valsalva’s maneuver or Trendelenburg’s position for increasing the cross-sectional
area of the jugular and common femoral veins. N#10 External and internal jugular veins; N#8 common femoral veins.
Data points for each of 7 volunteers are shown. Each colored square or circle represents the average of 3 measurements
of the designated vessel and volunteer. Not every volunteer volunteered to have all 3 vessels measured. Large blue dots
with error bars represent average percentage diameter increase from baseline and SD, respectively. B, Baseline (supine,
resting); H, humming; RT, reverse Trendelenburg; T, Trendelenburg; V, maximal Valsalva. Neither humming nor Valsalva
was tested in combination with Trendelenburg’s positions.
*P!0.05. Squares represent male subjects. Circles represent female subjects.
Humming and Ultrasonographic Visualization of Jugular Venous System Lewin et al
76 Annals of Emergency Medicine Volume ,.:July 

Address for correspondence: Matthew R. Lewin, MD, PhD,
University of California, San Francisco, Box 0208, 505
Parnassus Ave, San Francisco, CA 94143; 415-353-8309, fax
415-353-1799; E-mail aplysia99@yahoo.com.
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Volume ,.:July  Annals of Emergency Medicine 77