Evaluation of the Body Surface Area as Determ

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Cholecystodynamics refers to gallbladder con-

traction as substances induce contraction on the

gallbladder wall.1

Gallbladder motility (contractil-

ity) is important to assess because impairment of

motility has been demonstrated in some gallblad-

der diseases. Gallbladder motility has been studied

in a Nigerian population using the gallbladder

contraction index (GBCI)2

and the gallbladder

emptying rate (GBER).1,2

A conventional chole-

cystosonography technique is to use a standard-

ized fatty meal (SFM) to assess and compare

gallbladder functions.

Some anthropometric and pharmacologic factors

have been noted to affect gallbladder motility. Body

mass index was noted to negatively correlate with

GBCI.2

Opiates contribute to gallbladder stasis by

From the Federal Medical Centre, Abakaliki, Nigeria.

Correspondence: A. C. Ugwu, BSc, MSc, PGC-CT Federal

Medical Centre, Nigeria, F.M.B. 102, Abakaliki, Nigeria. E-mail:

[email protected].

The author acknowledges with deep appreciation Mr Otu

Emerson, director of the Jeomedics Ultrasound Centre, for his mate-

rial assistance and Mrs Ngozi Ugwu for her financial assistance.

DOI: 10.1177/8756479307311912

4 JDMS 24:48 January/February 2008

Evaluation ofBody Surface Areaas a Determinant ofCholecystodynamicsDue to Orally

AdministeredStandardizedSkimmed Milk

A. C. UGWU, BSc, MSc, PGC-CT

The author studied the relationship between

body surface area and both the gallbladder con-

traction index and gallbladder emptying rate.

Using the ellipsoid formula, gallbladder vol-

umes were sonographically measured in the

preprandial state and 20 minutes after a stan-

dardized fatty meal in 62 subjects. Gallbladder

contraction indices and emptying rates werecalculated. The body surface area of 61 subjects

who followed the study design was computed

from their height and weight measurements.

Parametric tests also were carried out, revealing

that there were no significant correlations

between body surface area and gallbladder con-

traction index and gallbladder emptying rate.

Dosing in cholecystodynamic studies may be

limited by lack of correlation between gallblad-

der emptying rate and body surface area.

Key words: body surface area, cholecystody-namics, milk, sonography


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BODY SURFACE AREA AS A DETERMINANT OF CHOLECYSTODYNAMICS / Ugwu 5

inhibiting ganglionic activity and neurogenic con-

tractions.3

One study has indicated that motilin

may play a physiological role in the regulation of

gallbladder emptying in a fasted state.4The traditional method of individualizing cyto-

toxic drug dose is to use body surface area (BSA),

which is equivalent to the 2D surface area of the

skin of an individual.5

Estimation of BSA is most

commonly done with a formula that was derived in

1916 by Du Bois and Du Bois,6

who examined

nine individuals of various ages, shapes, and sizes

and measured their body surface area directly with

molds. By trial and error, they derived a formula to

estimate body surface area. This formula was use-

ful because it correlates with the basal metabolic

rate. Body surface area is also proportional to

blood volume. The Du Bois formula was chal-

lenged in 1970 by Gehan and George,7

who

directly measured the skin surface area of 410

individuals. They found that the Du Bois formula

overestimated body surface area by 15% in 15% of

cases, but otherwise, the original formula was sur-

prisingly accurate, considering the small sample

size used in its derivation, and remains the most

popular way to measure BSA.

Body surface area has a rational use for inter-

species scaling and for calculating an initial start-

ing dose for a human phase I trial, based on prior

experience in laboratory animals.8

However, in the

sonographic assessment of gallbladder motility, a

standardized quantity of milk (usually a tin: 165

mL) has been adopted. Little data are available

relating to BSA on the gallbladder, so this study

aimed at evaluating the effect of body surface area

on gallbladder motility.

Materials and Methods

PATIENT ELIGIBILITY

Subjects with a positive history of hepatobiliary

disease were not eligible for the study, as well as

people with a history of diabetes, which has been

reported to have an effect on gallbladder motility.9

Volunteers younger than 18 years or with a history

of lactose intolerance were also excluded from the

study. Only healthy adults of Nigerian descent with

no history of diabetes or hepatobiliary disease were

included in the study. The subjects had to be aware

of the nature of the study and willingly provide

informed consent before entering the study.

Institutional review board or ethics board reviewand approval of the protocol at the center was

required.

EVALUATIONS

Each subject was scanned in the morning after

an overnight fast. Subjects had their weight (kg)

measured on a bathroom scale (Model H 89 LT

Blue), and height was measured on a calibrated

vertical wall.

Two serial sonograms were carried out on each

subject in supine position using a Sonoline SL-1machine with a 3.5-MHz sector transducer

(Siemens Medical Systems, USA Inc, Ultrasound

Group, Issaquah, Washington) as follows: before

ingesting a tin (165 mL) of evaporated skimmed

cows milk (trade name: Three Crowns) and 20

minutes postprandial. The subjects sat down while

ingesting milk and were supine throughout the

procedure. Milk was standardized in this way

because the fat content of a meal in healthy volun-

teers affects the modality of gallbladder empty-

ing.10

These procedures enabled variations of

gallbladder volumes with bile emptying to beobtained. The transducer was used to scan the right

upper quadrant of the abdomen after applying

ultrasound gel to the skin. After visualization of

the maximal gallbladder longitudinal outline, the

length and maximal antero-posterior diameter

(height) measurements were taken on arrested res-

piration with calipers crossing each other at 90

degrees, and then the transducer was rotated 90

degrees to obtain the maximal transverse dimen-

sion. This resulted in three orthogonal (perpendi-

cular) measurements (Figure 1a,b). Length, width,

and height measurements were taken from outer-

to-outer hyperechoic walls. Fasting gallbladder

measurements were taken in triplicate and the

mean values obtained by an imaging scientist who

is a sonographer. Body surface area (m2) was

obtained using the following formula derived by

Du Bois and Du Bois6: BSA = (weight 0.425

height 0.725) 0.007184, where weight is in kilo-

grams and height is in centimeters.


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6 JOURNAL OF DIAGNOSTIC MEDICAL SONOGRAPHY January/February 2008 VOL. 24, NO. 1

CHOLECYSTODYNAMICS

Gallbladder volumes were obtained using the

formula for volume calculation (approximation)

for the prolate ellipsoid. GBCI was computed as

the percentage decrement of postprandial size

(volume) from the initial size. GBER was obtained

as the change in volume divided by 20 minutes

(cm3/min).

STATISTICS

Data were not categorized to sex because previ-

ous studies in this population have not shown any

significant (P > .05) difference in GBER1

and

GBCI11

for men and women. SPSS 11.0 software

was used for summary statistics and correlation

analysis. The graph was plotted and regression

equation developed in Microsoft Excel Office

2000. After summary statistics of cholecystody-

namic parameters (GBCI and GBER) and BSA

was generated, the degree of linear relationship

between cholecystodynamic parameters and BSA

was investigated using Pearsons correlation coef-

ficient (r). Tests were two-tailed, with P < 0.05

indicating statistical significance.

Results

Fifty-two subjects volunteered in this study

between January 2005 and June 2006. Of the sub-

jects, 30 were men and 22 were women. Subjects

ages ranged from 18 to 63 years. The characteristics

of the 51 subjects are shown in Table 1 (1 subject

moved off the couch to make a phone call down-

stairs after milk ingestion and so was not included).

Data approximated a normal distribution (using val-

ues of skewness and kurtosis), and hence a para-metric test (Pearsons correlation) was carried out.

BSA ranged from 1.35 to 2.17, with a mean value

of 1.7642; GBCI ranged from 15.79 to 85.53, with a

mean value of 52.4207; and GBER ranged from

0.04 to 2.03, with a mean value of 0.7338.

BODY SURFACE AREA AND CHOLECYSTODYNAMICS

There was no significant relationship between

BSA and GBER, as well as between BSA and

GBCI. Figure 2 shows the relationship between

GBER and body surface area.

Discussion

The development of radiology of the biliary

tract has been punctuated at intervals by techno-

logical advances that affect medical imaging. The

first of these was the development of oral chole-

cystography, which depends on adequate absorp-

tion of the oral contrast medium from the small

FIGURE 1. Line drawings showing (A) a longitudinal section

of the gallbladder and (B) a transverse section of the gallbladder.

Height

Length

Width

TABLE 1.Characteristics of Subjects

Variable n Minimum Maximum Mean SD

BSA 61 1.35 2.17 1.7642 0.17723

GBCI 61 15.79 85.53 52.4207 17.64387

GBER 61 0.04 2.03 0.7338 0.44111

BSA, body surface area; GBCI, gallbladder contraction

index; GBER, gallbladder emptying rate.

A

B


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BODY SURFACE AREA AS A DETERMINANT OF CHOLECYSTODYNAMICS / Ugwu 7

intestine, its excretion from the liver with bile, the

patency of the cystic duct, and adequate concen-

tration by the gallbladder. This requires about 11

hours for completion.

According to Lamb,12

sonography is the modal-

ity of choice in assessing gallbladder changes.

Dynamic cholescintigraphy (DCS) has presently

been adopted as the gold standard to assess gall-

bladder function. A study13

has shown that

dynamic ultrasonography (DUS), performed using

simple technique, lacks diagnostic value in gall-

bladder dysfunction when dynamic cholescintigra-

phy is taken as a reference test. When gallbladders

that were ellipsoidal were subselected, the correla-

tion between DUS and DCS was noted to have

improved.14

Another research study by Cay et al15

showed that sonographic evaluation of gallbladder

contraction stimulated by a fatty meal provides

relatively reliable and reproducible results.

Therefore, this can be used for assessing patients with

biliary symptoms as a prior modality to cholecys-tokinin scintigraphy (CCKs-HBS) because it is a rel-

atively easier, safer, and available method with which

to make a definitive diagnosis in biliary dyskinesia.

The differences in the results of the sonographic

assessment of biliary functions could possibly result

from using one formula (in this study, only the

ellipsoid formula was used) to assess gallbladders

of various shapes, which obviously would create a

mathematical trade-off.

As demonstrated in this study, there is no sig-

nificant correlation between body surface area and

gallbladder motility indices. This relates to previ-

ous studies that did not establish any significant

correlation between gallbladder motility and some

anthropometric factors such as age,11

body mass

index,11 height, and weight,1

which implies that

BSA can be used for dosing in some therapeutic

procedures5,8

but cannot be used to determine the

quantity of milk to be taken by subjects in chole-

cystodynamic studies. A research study10

noted

that by applying a mathematical model to the

analysis of gallbladder volume sonography meas-

urements, it is possible to measure the flux of bile

through the gallbladder. Hence, further studies in

this area are required to investigate the relation-

ship between body surface area and influx of bile

into the gallbladder, which could be a factor in

cholesterol crystal precipitation and stone growth.

An obvious limitation of this study is the use of

2D sonography; 3D studies have obvious advan-tages over 2D studies. Volume sonography is

becoming highly used in the sonography labora-

tory and may well prove to be an appropriate tech-

nology to apply in future studies.16 In this study,

one imaging scientist (AC) took the measure-

ments. This was done to avoid possible interob-

server variations. Further studies on interobserver

reproducibility in the sonographic measurements

of gallbladder dimensions are recommended to

y = 0.614x - 0.3423

-0.5

0

0.5

1

1.5

2

2.5

0 0.5 1 1.5 2 2.5

BSA

GBER

FIGURE 2. A scattergram of gallbladder emptying rate on body surface area.


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8 JOURNAL OF DIAGNOSTIC MEDICAL SONOGRAPHY January/February 2008 VOL. 24, NO. 1

enable many imaging scientists to collect data in a

wide range of settings in future studies. Evaluation

of only subjects who volunteered for the study is

another nonrandom factor that may have contortedthe study population in this pilot study.

Conclusion

This study indicates that BSA does not correlate

with GBER. Dosing in cholecystodynamic studies

may be limited by lack of correlation between

GBER and BSA.

References

1. Ugwu AC: Cholecystodynamics: a new regression for-

mula. Pak J Med Res 2006;45:1721.

2. Ugwu AC, Ovuoba KN, Udo B, et al: Sonographic

assessment of gallbladder motility in the Ibo population

of Nigeria: a feasibility study.J Diagn Med Sonography

2007;23:410.

3. Guarraci FA, Pozo MJ, Palomeres SM, et al: Opioid ago-

nists inhibit excitatory neuromuscular junction in guinea

pig gallbladder. Available at: www.handheldmed.cn.

Accessed December 9, 2007.

4. Luiking YC, Pecters TL, Stolk MF, et al: Motilin induces

gallbladder emptying and anthral contractions in the fasted

state in humans. Gut1998;42:830835.

5. Miller AA, Rosner GL, Egorin MJ, et al: Prospective eval-uation of body surface area as a determinant of paclitaxel

pharmacokinetics and pharmacodynamics in women with

solid tumors. Clin Cancer Res 2004;10:83258331.

6. Du Bois D, Du Bois EF: A formula to estimate the

approximate surface area if height and weight be known.

Arch Intern Med1916;17:863871.

7. Gehan EA, George SL: Estimation of human body sur-

face area from height and weight. Cancer Chemother

Rep 1970;54:225235.

8. Freireich EJ, Gehan EA, Rall DP, et al: Quantitative

comparison of toxicity of anticancer agents in mouse,

rat, hamster, dog, monkey, and man. Cancer Chemother

Rep 1996;50:219231.

9. Guliter S, Tlmaz S, Karakan T: Evaluation of gallbladder

volume and motility in non-insulin-dependent diabetes

mellitus.J Clin Gastroenterol 1990;98:10011007.

10. Pallota N: Ultrasonography in the assessment of gall-

bladder motor activity.Dig Liver Dis 2003;3:6769.

11. Ugwu AC: Sonographic assessment of gallbladder sizes

and contraction index in an adult Nigerian population.

Completed MSC research work, 2006.

12. Lamb CR: Ultrasonography of the liver and biliary tract, in

Kay WJ, Brown NO (eds): Problems in Tertiary Medicine.

Philadelphia, J. B. Lippincott, 1991, pp 111121.

13. Pons V, Ballesta A, Pouce M, et al: Dynamic ultrasonog-

raphy in the diagnosis of gallbladder dysfunction: relia-

bility of a simple method with easy clinical application.

Gastroenterol Hepatol 2003;26:812.

14. Siegel A, Kuhn JC, Crow H, et al: Gallbladder ejection

fraction: correlation of scintigraphic and ultrasono-

graphic techniques. Clin Nucl Med2000;25:16.

15. Cay A, Imamoglu M, Sarihan H, et al: Ultrasonographic

evaluation of fatty meal stimulated gallbladder contrac-

tion in the diagnosis of biliary dyskinesia in children.

Acta Paediatr2006;95:838842.16. Hashimoto S, Goto H, Hirooka Y, et al: An evaluation of

threedimensional ultrasonography for the measurement of

gallbladder volume.Am J Gastroenterol 1999;94:3492.


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Article: Evaluation of Body Surface Area as a Determinant of

Cholecystodynamics Due to Orally Administered Standardized

Skimmed Milk

Author: A. C. Ugwu, BSc, MSc, PGC-CT

Category: Abdomen (AB)

Credit: 0.5 CME

Objectives: After studying the article titled Evaluation of

Body Surface Area as a Determinant of Cholecystodynamics

Due to Orally Administered Standardized Skimmed Milk,you will be able to:

1. Discuss factors involved with gallbladder motility.

2. Explain the method for calculating body surface area.

3. Describe the gallbladder contraction index and emptying

rate.

1. Cholecystodynamics is studied with which of the fol-

lowing methods?

a. Gallbladder contraction index

b. Gallbladder fractional change

c. Gallbladder filling rated. Gallbladder length times width

2. The body surface area formula used in this study most

closely correlates with which of the following?

a. Exercise-induced functional change

b. Circulating blood index

c. Change in rate over time

d. Basal metabolic rate

3. This study indicated which of the following relationships

between body surface area (BSA) and gallbladder motil-

ity (GM)?

a. As BSA increases, GM decreases

b. As BSA increases, GM increases

c. As BSA decreases, GM decreases

d. There was no relationship

4. Which of the following best describes cholecystodynamics?

a. Gallbladder relaxation

b. Gallbladder contraction

c. Gallbladder location

d. Gallbladder sludge

5. Which two measurements were performed in this study

to calculate the gallbladder motility?

a. The length and maximal antero-posterior diameter

b. Maximum dimensions before and after

c. The maximum length in the supine and right lateral

decubitus positions

d. Area of the gallbladder in two planes

6. What method of evaluation can be used prior to cholecys-

tokinin scintigraphy for diagnosis of biliary dyskinesia?a. Gallbladder contraction

b. Gallbladder concentration

c. Gallbladder volume

d. Gallbladder area

7. Which of the following can be used to aid in dosing for

gallbladder motility?

a. Age

b. Height

c. Weight

d. None of the above

8. Which of the following was not a limitation of this study?

a. 3D was used to calculate volumes

b. One observer performed the measurementsc. Sample size was small

d. Generalizability limited those similar to the popula-

tion studied

9. Figure 1 demonstrates the measurements performed for

which results?

a. Gallbladder fractional change

b. Gallbladder filling rate

c. Gallbladder length times width

d. Gallbladder contraction index

10. Which of the following was used to simulate a meal?

a. Evaporated ice cream

b. Evaporated skimmed cows milkc. Dairy shake

d. Condensed milk

JDMS 24:910 January/February 2008 9

SDMS-JDMS CME TEST

Evaluation of the Body Surface Area as Determ

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