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Hindawi Publishing CorporationCardiology Research and
PracticeVolume 2012, Article ID 723418, 6
pagesdoi:10.1155/2012/723418
Clinical Study
Transoesophageal Echocardiography for Monitoring LiverSurgery:
Data from a Pilot Study
Filipe Pissarra,1 Antonio Oliveira,1 and Paulo Marcelino2
1 Anesthesiology Department, Hospital Curry Cabral, Rua da
Beneficência 8, 1069-166 Lisbon, Portugal2 CEDOC, Faculdade de
Ciências Médicas, Lisbon, Portugal
Correspondence should be addressed to Filipe Pissarra,
[email protected]
Received 24 April 2011; Revised 18 December 2011; Accepted 14
February 2012
Academic Editor: Antoine Vieillard-Baron
Copyright © 2012 Filipe Pissarra et al. This is an open access
article distributed under the Creative Commons Attribution
License,which permits unrestricted use, distribution, and
reproduction in any medium, provided the original work is properly
cited.
A pilot study aimed to introduce intraoperative monitoring of
liver surgery using transoesophageal echocardiography (TEE)
isdescribed. A set of TEE measurements was established as a
protocol, consisting of left atrial (LA) dimension at the aortic
valveplane; mitral velocity flow integral, calculation of stroke
volume and cardiac output (CO); mitral annular plane systolic
excursion;finally, right atrial area. A total of 165 measurements
(on 21 patients) were performed, 31 occurring during hypotension.
The con-clusions reached were during acute blood loss LA dimension
changed earlier than CVP, and, in one patient, a dynamic left
ventricu-lar (LV) obstruction was observed; in 3 patients a
transient LV systolic dysfunction was documented. The comparison
between 39CO paired measurements obtained by TEE and PiCCO2
revealed a statistically significant correlation (P < 0.001, r =
0.83). In thispilot study TEE successfully answered the questions
raised by the anesthesiologists. Larger cohort studies are needed
to addressthis issue.
1. Introduction
In major surgery haemodynamic complications are likely tooccur;
hence for this reason monitoring is necessary to tracephysiological
parameters. There are several commerciallyavailable monitoring
systems, but transoesophageal echocar-diography (TOE) was not as
extensively studied in noncar-diac [1] as it was in cardiac surgery
[2–5]. Due to its uniqueability for cardiac imaging, assessing left
ventricular (LV)function and right heart chambers dimensions, it is
consid-ered promising [5].
The questions faced by anaesthesiologists in noncardiacsurgery
are quite different from those in cardiac surgery,where valvular
diseases, prosthesis placement and compli-cations are the most
relevant. Questions on LV function oracute change in volume status
and hypotension are moreconcerning in noncardiac surgery. Good
candidates for suchmonitoring are patients submitted to major
surgery, espe-cially those undergoing liver surgery or even
transplantation[6–8]. During this type of surgery, haemodynamic
instabilitycan occur during liver manipulation or due to
associatedblood loss.
In our centre, the usual means for monitoring include
thecontinuous monitoring of the central venous pressure (CVP)and,
in selected cases, the continuous monitoring of cardiacoutput (CO)
through the use of the PiCCO system. Pulmo-nary artery catheters,
used more often in the past, are nowseldom used. As resident
anaesthesiologists felt an increasingneed for a more accurate
monitoring, a pilot study aimed tointroduce intraoperative
monitoring of liver surgery usingTOE was performed. This study was
aimed to evaluate theplace of TOE for liver surgery monitoring and
to compareefficiency of TOE measurements with PVC and PiCCO
todiagnose hemodynamic instability causes. A set of TOEmeasurements
was established as a protocol, after previousdiscussion with the
anaesthesiology staff about the requiredinformation. A comparison
between the information derivedfrom the monitoring devices used was
also performed.
2. Material and Methods
2.1. Patients. This was a 1-year prospective study, which
in-cluded patients submitted to liver surgery and enrolled with-out
previous selection, although limited to the availability of
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2 Cardiology Research and Practice
the anesthesiologists (FP and AO), intensive care specialistwith
expertise in the area (PM), and echocardiographyequipment. This
pilot study was open with the anaesthesiol-ogists being aware of
TOE information. All data was digitallyrecorded for later
visualisation, if deemed necessary.
Patients were characterized by age, gender, and body sur-face
area. Main diagnoses (for surgical purposes) and comor-bidities
were also collected. The main demographic andclinical
characteristics of the enrolled patients are presentedin Table
1.
The study protocol was reviewed by the local EthicsBoard, and an
informed statement was obtained previous tosurgery.
2.2. Methods. During liver surgery, hypotension and
livermanipulation (reported by the surgeons) were the most
re-garded situations. Hypotension was considered when meanarterial
blood pressure was 60 mmHg or lower, and data wasthoroughly
analysed. Blood loss was considered either by thereports from the
surgeons or by a decrease in haemoglobinlevels of more than 2
gr/dL. Other possible aetiologies wereevaluated according to the
available monitoring devices.
Patients were anaesthetised using a general balanced
an-aesthesia, having been intubated after anaesthesia
induction.
CVP monitoring was performed continuously using acentral venous
line connected to a Philips M4 monitor, wherethe arterial pressure
and heart rate were also registered. Thearterial pressure was
monitored invasively using an arterialcatheter inserted into a
radial or femoral artery. The invasiveCO, when used, was determined
using a PiCCO 2 system, forwhich a central venous line and a
femoral arterial line wereinserted and then calibrated according to
the manufacturer’sinstructions.
2.3. Echocardiography. The TOE monitoring was performedusing a
Siemens ACCUSON X300 and a General ElectricLOGIC P6, both equipped
with a multiplane transoesophag-eal probe.
Before the study started, a consensus was established withthe
anaesthesiologists to determine the information neededfor
monitoring. The information considered necessary wasprevious
surgery knowledge of the heart anatomy and func-tion; CO; left
ventricular (LV) performance; data on volumestatus; right heart
chamber evaluation. Special concern wasaddressed to the TOE
parameters; they needed to be easilyobtained, not time consuming,
in order to permit quick ther-apeutic decisions. It was also
established that intragastricviews should not be used so as to
avoid interference with thesurgical field. The choice of invasive
monitoring was carriedout by the anaesthesiologist’s judgement and
independent ofstudy purposes.
After anaesthesia induction, a transoesophageal probewas
inserted and the first images obtained. A global exam-ination was
first performed and global and segmental wallmotion abnormalities
were evaluated, as well as valvular re-gurgitations. The following
sets of measurements were cho-sen in order to obtain the
information previously required bythe anaesthesiologists. The CO
was obtained through the
Table 1: Demographic and clinical characterization of
studiedpatients (n = 21).
Age (years, mean, and sd) 54.1 ± 17.6Male (n) 12
Body surface area (m2, mean and sd) 1.73 ± 0.17Liver resection
due to metastatic disease (n) 14
Liver resection due to other diseases (n) 4
Liver transplant (n) 3
Past history:
Coronary artery disease 1
Hypertension 2
Diabetes mellitus 2
Other 1
mitral velocity time integral (VTI), measured as follows.
Firstthe left ventricular influx by evaluation of the mitral
E/Aratio in the 4-chamber view was analysed. Secondly, left
ven-tricular CO was assessed by measuring the mitral VTI,
calcu-lating the stroke volume index (SVI) and multiplying it
byheart rate (Figure 1). Necessary information with regards tothe
width of the mitral valve orifice was measured in the sameview
(Figure 2). The LV function was assessed through theexternal mitral
annulus systolic excursion (MAPSE, consid-ered the most feasible
parameter compared to ejection frac-tion and other volumetric
parameters) obtained in the same4-chamber view. At the aortic valve
plane, during diastolewhen the three aortic cuspids were visible,
visible left atrium(LA) area and dimension, obtained from the LA
first echo toaortic valve (Figure 3), were determined. Lastly, the
assess-ment of right heart chambers was performed; the probe
wasrepositioned for the assessment of the right atrium and
ven-tricle. The measurement of the right atrial area was
empha-sized (Figure 4). All TOE measurements were performed
atend-expiration, and other changes detected during TOE
wereregistered. TOE evaluation was performed routinely every15
minutes of surgery or whenever considered necessary ifhypotension,
blood loss, or liver manipulation were report-ed.
An LV systolic dysfunction was considered wheneverMAPSE was
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Cardiology Research and Practice 3
Figure 1: Determination of the mitral VTI.
Figure 2: Determination of the mitral annulus diameter.
3. Results
Overall, 165 TEE dataset measurements were performed, andin 5
patients a PiCCO2 system was present. Overall, 31 reg-istries were
performed during hypotension. Of these, 16 (5patients) were due to
hemorrhage, 9 (5 patients) without ob-vious cause, and 6 (4
patients) due to liver manipulation.
In the haemorrhage evaluation the LA and RA dimen-sions
decreased in all patients, as well as CVP, but it
occurredsimultaneously in only two occasions. In the
remainingmeasurements (n = 29), TOE modifications preceded
CVPchanges by 10 to 15 minutes. In Table 2, and in Figure 5,
agraphic representing a registry during an acute blood lossand
changes in CVP and visible LA area and dimension ispresented. It
was also observed that the LA dimensiondecreased almost uniformly
by nearly 20% (19.8% ± 0.9).The comparative data of the parameters
previous to haemor-rhage and during haemorrhage is presented.
There were 6 cases of liver manipulation. In two
episodeshypotension occurred without changes in CVP.
Interestingly,LA and RA dimensions decreased during liver
manipulation,but CVP and CO remained unchanged. The comparativedata
obtained previous to and during liver manipulation arepresented in
Table 3.
In 9 cases (5 patients), a hypotensive episode was docu-mented
without blood loss. Within this group, in two cases atypical change
in volume status was detected by TOE, butnot by CVP; in one case, a
decreased volume status was
Figure 3: Determination of visible LA area and dimension
(distancefrom the first echo from LA to aortic valve) in the aortic
plane.
Figure 4: Determination of the right atrial area.
identified by both methods; in two cases there was no
changeobserved by the two methods; in three episodes (3 patients)a
systolic dysfunction was detected by TOE (decrease inCO and MAPSE)
in patients with previous normal LV con-tractility. This LV
dysfunction was transient and, due to glob-al LV hypokinesia, the
recovery was observed within a fewminutes. No apparent cause for
this phenomenon wasdetected.
Only one patient presented an LV dysfunction, detectedprevious
to surgery, suffering from ischemic heart disease.During surgery,
hypotension was detected during a massiveblood loss, and LV
dysfunction exacerbated, along withexacerbated wall motion
abnormalities. Vasopressor andinotropic support was started, some
recovery of LV contrac-tility was observed but the patient remained
hypotensive.This patient died in the early postoperative period in
theIntensive Care Unit.
Overall, TOE-derived CO varied more markedly thanPiCCO2-derived;
the mitral E/A wave form changed duringanaesthesia induction and
remained less than one duringmost part of the surgery. The first
obtained mean values forthis parameter were 0.99± 0.47 and for the
remaining 0.83±0.36 (P = 0.001). However no relevant information
couldbe obtained from this parameter during surgery, even
duringhypotension/blood losses.
By linear regression analysis, considering CVP as adependent
variable and LA dimension and RA area as in-
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4 Cardiology Research and Practice
Table 2: Comparison of hemodynamic and echocardiographical data
in hypotension due to blood losses (16 sets of measurements in
5patients).
Parameter Data before hypotension Data during hypotension P
HR (bpm) 71.7± 9.4 74 ± 11.8 nsCVP (mmHg) 6.7± 1.9 5.2± 2.2
0.01LA area (cm2) 9.1± 3.5 5.4± 2.2 0.001LA dimension (mm) 28.5±
4.7 22.8± 4.3 0.001RA area (cm2) 15.1 ± 2.4 13.8 ± 2.6 0.01Mitral
E/A 0.73± 0.33 0.76± 0.34 nsPiCCO CO (mL/min) 4322 ± 452 3921 ± 404
0.001TOE CO (L/min) 4571 ± 472 3622 ± 463
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Cardiology Research and Practice 5
0
1000
2000
3000
4000
5000
6000
0 1000 2000 3000 4000 5000 6000 7000
CO obtained by PiCCO
CO
obt
aine
d by
TE
E
Figure 6: Dispersion graphic comparing the cardiac output
ob-tained by PiCCO2 and TEE (P < 0.001, r = 0.83).
may be considered an early adaptive phenomenon in order toensure
LV filling pressure (during volume loss the decrease inLA dimension
prevents further decrease in LA pressure andconsequent LV filling
pressure). Interestingly, the same chan-ges were observed during
liver manipulation, which results indecreased preload due to
vascular compression. This infor-mation is important and allows the
anaesthesiologist to an-ticipate adequate therapeutic actions. To
our knowledge, thisfinding has not yet been described in the
literature. However,RA area was the parameter with a statistically
significant as-sociation with CVP, not the LA dimension.
The present study evaluated preload not preload depen-dency,
using comparative data from static parameters.Among the possible
parameters, left ventricular end diastolicarea (LVEDA) could not be
considered as transgastric viewswere not obtained [9]. Dynamic
concepts for fluid admin-istration [10, 11] and preload dependency
were not alsoconsidered in the present study. Only when PiCCO
systemwas inserted could the anaesthesiologists evaluate the
systolicvolume variation, and fluids were often administered
when-ever this parameter was >15%, regardless of
haemodynamicstatus. Several TOE parameters can be used to assess
preloaddependency [12, 13], and in some settings they were usedto
guide intraoperative fluid administration. In this regardwe must
consider that the protocol was formulated in orderto detect and
characterize acute changes, not to guide fluidadministration. The
emphasis was acute volume loss mainlyblood losses that should be
rapidly treated. In other words,we focused on acute phenomena.
CO has gained particular attention as a way of accessingthe
global circulatory status, but how accurately this variablemeasures
the adequacy of circulatory flow is yet to be estab-lished. Perhaps
the usefulness of CO consists in detectingchanges in this variable
during surgery, especially duringepisodes of instability.
Considering this as the main use ofCO monitoring, the changes are
more important than itsabsolute value. Using TEE, CO was monitored
through themitral pulsed-Doppler influx, an occasionally used
method[14, 15]. In this method mitral valve annulus was used asa
surrogate for cross-sectional area. The accuracy of mitralvalve
stroke volume is debatable. The mitral valve orifice doesnot have a
perfect geometrical shape; thus it is not used byinvestigators. As
we decided not to use intragastric views in
order not to interfere with surgery, this was the possible,
non-time-consuming method. The correlation obtained with thePiCCO
system was statistically significant (P < 0.001), withr value of
0.83. Although the methods are different theimportance of this
parameter is its changes during acuteevents, and in this regard
both methods were reliable,although TOE-derived CO presented
greater variability thanPiCCO-derived CO.
Left ventricular function was monitored through mitralvalve
annular plane systolic excursion, a method widely usedand tested
[16, 17]. The LV function monitoring abilityis perhaps one of the
most important features of TOEmonitoring. No other means is
comparable not even theclassic methods. It was a valuable tool in
the approach ofhypotension in one patient, guiding inotropic and
vasopres-sor support and detecting a transient LV dysfunction in
other3 episodes of hypotension. This detection was only
possiblebecause TOE monitoring was present, and we could notdetect
a cause for this phenomenon. Also, we could not find asimilar
description in the literature. Although an experiencedobserver
could detect changes in LV function subjectively,MAPSE was used in
this pilot study as an objective measure-ment. One should remember
that LV systolic dysfunction canalso be easily detected by
simultaneous changes in mitral VTIand MAPSE.
Other possibilities of TOE were not observed in thisstudy, for
example, the detection of right heart overload andalterations in
cardiac chambers, mainly due to gas embolismor thrombus formation.
In a larger cohort study they couldpossibly be observed.
5. Study Limitations
In this pilot study the preload determination was
consideredrather than preload dependency. The invasive
counterpartfor preload dependency estimation can be the systolic
vol-ume variation, and several TOE parameters can be used
toevaluate, such as the analysis of superior vena cava, an
easyprocedure to carry out during TOE examination. This needwas not
particularly expressed by anaesthesiologists, morefocused on acute
and life-threatening phenomena and LVfunction. But in future
protocols this item can be used. Someother measurements could be
considered but, as we limitedthe information to a
non-time-consuming acquisition inorder to describe an easy-to-use
tool during anaesthesia,most information was limited. More complex
data can beobtained through this technique which, yet due to
timeconstraints typical of an operating theatre, went beyond
thescope of this study.
In the future it is also necessary to enrol patients whopresent
atrial fibrillation, in order to fully understand thelimitations of
TOE monitoring.
Another question regards TOE possibilities. Right
heartdysfunction and/or overload could not be detected in
thepatients studied, but it can be an advantage in the use of
TOE.Other conditions resulting from the cardiac imaging (valvu-lar
regurgitations, intracardiac masses or thrombi) can alsopresent an
advantage, not observed in the studied patients.
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6 Cardiology Research and Practice
6. Conclusion
The use of a TOE monitoring was possible during liver sur-gery,
in order to assess volume status, LV function, and CO.In five
patients monitored with the PiCCO system, a statisti-cally
significant correlation between CO obtained by mitralvalve VTI was
obtained. TOE was also useful during episodesof hypotension,
detecting changes in volume status earlierthan invasive tools.
TOE is a possible and valuable tool in monitoring liversurgery,
and its use by anaesthesiologists should be encour-aged. More data
is needed to establish its role in other non-cardiac surgery
monitoring.
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