13 Klein Al, Hatle LK, Burstow DJ, et al. Comprehensive Doppler assessment of right ventricular diastolic function in cardiac amyloidosis. J Am Coll Cardiol 1990 ...
British Journal of Anaesthesia 87 (5): 711±7 (2001)
Use of multi-plane transoesophageal echocardiography in visualization of the main hepatic veins and acquisition of Doppler sonography curves. Comparison with the transabdominal approach R. Meierhenrich*, A. Gauss, M. Georgieff and W. SchuÈtz Department of Anaesthesiology, University of Ulm, SteinhoÈvelstr. 9, D-89075 Ulm, Germany *Corresponding author The role of multi-plane transoesophageal echocardiography (TOE) in the visualization of the three main hepatic veins and acquisition of Doppler sonography curves has not been established. We have studied this diagnostic option of TOE in 34 patients during general anaesthesia. The ®ndings were compared with the results of conventional transabdominal sonography (TAS). Using TOE, each of the three main hepatic veins could be visualized in all patients. In contrast, TAS allowed adequate two-dimensional visualization of the right, middle, and left hepatic vein in only 97%, 85%, and 61% of the patients, respectively. Adequate Doppler tracings of the right and middle hepatic vein could be obtained in 100% and 97% of the patients by TOE and in 91% and 50% of the patients by TAS. Doppler tracings of the left hepatic vein could only be acquired in 18% of the patients by TOE, but in 47% of the patients by TAS. As blood ¯ow may be calculated from the diameter of the vessel, velocity time integral of the Doppler curve and heart rate, TOE may provide an interesting non-invasive tool to monitor blood ¯ow in the right and middle hepatic vein. Br J Anaesth 2001; 87: 711±7 Keywords: monitoring, transoesophageal echocardiography; liver, blood ¯ow; liver, hepatic perfusion; measurement techniques, Doppler echocardiography; heart, right heart dynamics Accepted for publication: July 13, 2001
Assessment of hepatic and splanchnic perfusion is of scienti®c and clinical interest. Transabdominal Doppler ultrasound has been proposed as a non-invasive technique to assess hepatic vein ¯ow,1±3 but this approach is associated with several limitations. First, the intra-operative application of transabdominal ultrasound during abdominal or thoracic surgery is not feasible because of interference with the surgical ®eld. Second, in many mechanically ventilated patients, especially after intra-abdominal surgical procedures, trans-abdominal application of ultrasound does not deliver images of satisfactory quality. The possibility of assessing hepatic vein ¯ow using transoesophageal echocardiography (TOE) was ®rst mentioned by Pinto and coworkers in 1991.4 This group was unable to visualize and describe in detail the anatomy of the different hepatic veins using their monoplane transoesophageal echoprobe. Multiplane transoesophageal echoprobes have since become widely available in many hospitals. Therefore, the main objective of the present study was to evaluate the use of multi-plane TOE in the visualization of the main hepatic
veins and acquisition of analysable Doppler sonography curves. The second objective was to compare the transoesophageal technique with the conventional transabdominal approach.
Methods Patients We studied 34 patients undergoing abdominal surgery under general anaesthesia and mechanical ventilation. The study was approved by the ethics committee of the University of Ulm. Written informed consent was obtained from all patients before inclusion in the study. All patients were without known cardiovascular disease and were demonstrated to be in sinus rhythm by an electrocardiogram. According to the ASA criteria, 14 patients were classi®ed as group I, 14 patients as group II and six patients as group III. The mean age was 46.5 and ranged from 23 to 80 yr. After induction of general anaesthesia and endotracheal intubation, patients' lungs
Ó The Board of Management and Trustees of the British Journal of Anaesthesia 2001
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were mechanically ventilated (FIO2 0.3±0.4; PEEP 5 cm H2O) with a tidal volume of 8±10 ml kg±1 at a ventilatory frequency of 8±10 breaths min±1 adjusted to maintain endtidal PCO2 between 35 and 40 mm Hg.
Sonography and Doppler sonography measurements Transabdominal approach
After induction of general anaesthesia, transabdominal recordings of the right, middle, and left hepatic vein were
obtained using a Hewlett Packard echocardiograph (Sonos 5500, Hewlett-Packard Inc., Andover, MA, USA) with a 2.5 MHz transducer. For visualization of the right hepatic vein a lateral thoracic approach was used, for visualization of the middle and left hepatic vein a subxiphoidal or right subcostal view was chosen. Two-dimensional pictures of the hepatic veins were obtained in the B-mode. Subsequently blood-¯ow velocities in each hepatic vein were acquired by use of pulsed Doppler (PW)-mode. The Doppler sample-volume was placed in the centre of the vessel, 1±3 cm from its junction with the inferior vena cava.
Fig 1
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Visualization of main hepatic veins by use of TOE
Correction of the angle between the Doppler beam and long axis of the hepatic vein was performed for each Doppler measurement using the software of the echocardiograph. Two-dimensional pictures and Doppler signals were obtained at the end of expiration along with lead II of the ECG and stored on a magneto-optical disc. To verify the end of expiration, an external breathing circuit pressure gauge (Fa. Draeger, LuÈbeck, Germany) was connected to the echocardiograph to visualize the airway pressure on the screen. Analysis of the echo data was performed off line using the software of the echocardiograph. Two-dimensional images and ¯ow velocity curves were judged adequate for analysis only when clear signals were depicted at the end of expiration. Transoesophageal approach
After acquisition of the transabdominal views a 5.0 MHz multi-plane transoesophageal probe (Omniplane I, HewlettPackard Inc., Andover, MA, USA) was inserted and connected to the same echocardiograph. To visualize the hepatic veins the tip of the probe was advanced into the antrum of the stomach and ¯exed anteriorly. By rotating the probe clockwise and adjusting the imaging angle of the transducer array to 40±80° a saggital view of the inferior vena cava and the right hepatic vein was obtained. By rotating the probe counter-clockwise and increasing the angle of the transducer array to 50±90° the middle hepatic vein was visualized, by further counter-clockwise rotation of the probe and increasing the angle of the transducer array to 80±130° an image of the left hepatic vein was acquired.
When feasible, a two-dimensional picture of each hepatic vein was acquired in the B-mode and a Doppler sonography curve was obtained in the PW-mode. As described for the transabdominal approach the images were recorded along with an ECG-lead at the end of expiration and stored on a magneto-optical disc. Analysis of the Doppler sonography curve
Hepatic venous ¯ow during a cardiac cycle can be divided into a systolic forward ¯ow, diastolic forward ¯ow, and a diastolic reversed ¯ow induced by atrial contraction.2±4 Sometimes, also, a small systolic reversed ¯ow can be identi®ed. Peak ¯ow velocities and velocity time integrals of the four phases were measured by manual planimetry using the integrated software of the echocardiograph. The velocity time integral is the calculated area under the Doppler curve over a speci®ed period.5 The velocity time integral represents the distance the blood travels during the speci®ed period. The total velocity time integral during one cardiac cycle was determined by addition (forward ¯ow) and subtraction (reversed ¯ow), respectively, of the four single velocity time integrals. Calculation of the blood ¯ow in the hepatic veins
Blood ¯ow in a distinct hepatic vein was calculated using the formula: Blood ¯ow = VTI3p (D/2)23HR (VTI: total velocity time integral of one cardiac cycle, p (D/2)2 crosssectional area of the vessel, HR: heart rate).6 7 The diameter (D) of the vessel was determined at the same part of the vessel, where the PW-Doppler sample volume was placed.
Fig 1 (A) Two-dimensional picture of inferior vena cava (VCI) and right hepatic vein (RHV) obtained by the transoesophgeal approach (multi-plane angle 53°). (B). Two-dimensional picture of middle hepatic vein (MHV) (multi-plane angle 99°). (C) Two-dimensional picture of left hepatic vein (LHV) (multi-plane angle 124°).
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Fig 2 Characteristic Doppler sonography curve of middle hepatic vein obtained by the transoesophageal approach. The ¯ow pattern shows a systolic forward ¯ow, a diastolic forward ¯ow and a small diastolic reversed ¯ow, induced by atrial contraction.
Table 1 Percentage of patients revealing a systolic reverse ¯ow and diastolic reverse ¯ow in the main hepatic veins (HV). Results of the transoesophageal (TOE) and transabdominal (TA) approach
Right HV Middle HV Left HV
Systolic reverse ¯ow
Diastolic reverse ¯ow
TOE
TA
TOE
TA
15% (5/34) 6% (2/33) 16% (1/6)
3% (1/31) 0% (0/17) 12% (2/17)
53% (18/34) 58% (19/33) 83% (5/6)
29% (9/31) 17% (3/17) 35% (6/17)
Heart rate was derived from the ECG recorded together with the Doppler images.
Statistical analysis Discrete variables were described as absolute and relative frequencies. All continuous variables were presented as median (range). Differences between transthoracic and transoesophageal data were compared using the Mann±Whitney Rank Sum Test. Statistical signi®cance was assumed when the P-value was
