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Abstract

  1. Top of page
  2. Abstract
  3. PATHOGENESIS AND PHYSIOLOGY OF CARDIOVASCULAR INSTABILITY DURING ORTHOTOPIC LIVER TRANSPLANTATION
  4. COMPLICATION COMPARISON OF PAFC VS. TOE
  5. COMPARISON OF TOE TO ESTABLISHED PRACTICE
  6. SUMMARY
  7. REFERENCES

Patients undergoing orthotopic liver transplantation frequently display considerable physiological changes during the procedure as a result of both the disease process and the surgery. Anaesthesia is often challenging and relies upon advanced monitoring techniques to provide data pertinent to peri-operative management. Traditionally the pulmonary artery flotation catheter has been regarded as the gold standard for cardiac output and right heart monitoring. This review examines whether trans-oesophageal echocardiography merits a place in the continuing evolution of this technically advanced and challenging anaesthetic field. Liver Transpl 12:1577–1583, 2006. © 2006 AASLD.

The anaesthetic management of patients undergoing orthotopic liver transplantation (OLT) is complicated and often challenging. The procedure itself predisposes to inherent cardiovascular instability and despite pre-operative screening for suitability for transplantation, patients frequently present with both independent coexistent pathologies and dysfunction of other physiological systems consequent upon, or associated with the cause of their end-stage liver disease. Rapid and potentially catastrophic haemodynamic, metabolic and coagulation changes frequently occur intraoperatively which require early and accurate identification in order to allow expedient management. Pulmonary artery flotation catheterisation (PAFC) is an established intravascular monitoring tool which, whilst providing direct measurements, only indirectly offers left sided cardiac information. It is unable to demonstrate structural abnormality and provides limited dynamic information. By contrast, trans-oesophageal echocardiography (TOE) provides direct visualisation of cardiac structure, filling and dynamic function, and has the distinct advantage of remaining a relatively non-invasive procedure.

PATHOGENESIS AND PHYSIOLOGY OF CARDIOVASCULAR INSTABILITY DURING ORTHOTOPIC LIVER TRANSPLANTATION

  1. Top of page
  2. Abstract
  3. PATHOGENESIS AND PHYSIOLOGY OF CARDIOVASCULAR INSTABILITY DURING ORTHOTOPIC LIVER TRANSPLANTATION
  4. COMPLICATION COMPARISON OF PAFC VS. TOE
  5. COMPARISON OF TOE TO ESTABLISHED PRACTICE
  6. SUMMARY
  7. REFERENCES

Perioperative cardiovascular instability may result from pre-existent comorbidity both related and unrelated to the primary liver disease as well as perioperative changes resulting directly from the procedure.

Patients with end stage liver disease often have deranged cardiovascular physiology, presenting with a high cardiac output and a low systemic vascular resistance. This low cardiac afterload has the potential to mask coexistent cardiovascular disease from pre-operative detection.

A recent review of cardiac morbidity and mortality in patients presenting for OLT suggests that the incidence of significant pathology is much higher than has been previously anticipated.1 Indeed Carey et al. demonstrated that 32% of patients over the age of 50 put forward for OLT pre-operative evaluation had moderate or severe coronary artery disease at coronary angiography. Whilst 58% of these were known to have coronary artery disease, the remaining 42% had undiagnosed moderate or severe coronary arterial stenosis (Stenosis 30-70%, > 70% respectively).2

It has been well understood since being first demonstrated in the Framingham studies3 that the incidence of coronary artery disease increases with age. As the average age of liver transplantation patients continues to rise, coronary artery disease inevitably becomes an increasingly prevalent and clinically significant comorbidity amongst these subjects. This point is reinforced by Zetterman et al., who undertook a quality of life and mortality study of 735 liver transplantation patients, and found that although quality of life at one year was equal in over 60 year old recipients to that of younger patients, they had a statistically greater mortality rate which was attributed to age-related non-hepatic problems including cardiac pathology (19% vs. 10% mortality at one year; P = 0.004).4

In addition to unrelated coexistent cardiac pathology, there are other key processes which although less common, may also have profound effects on the perioperative course.

The hepatopulmonary syndrome, which comprises a triad of liver dysfunction, intrapulmonary vasodilatation and hypoxaemia, was until relatively recently considered a contra-indication for OLT. However, since this has been demonstrated to reverse following successful liver transplantation it has now become an acceptable condition for surgery, despite a potentially stormy perioperative course.5 This has had the effect of swelling the proportion of patients with pulmonary comorbidity undergoing OLT and making effective cardiovascular monitoring ever more important.

A more precarious situation is that in which pulmonary hypertension coexists with portal hypertension (the portopulmonary syndrome). In the absence of tricuspid regurgitation this may not be identified either clinically or by pre-operative echocardiography and may only be revealed upon flotation of the PAFC in the intraoperative phase.6 The pathological process involved in the development of pulmonary hypertension remains poorly understood, but is likely to involve both pulmonary macro and microvascular thromboembolic events and humoral factors compounded by a hyperdynamic system.7 Nevertheless, the mortality associated with the portopulmonary syndrome during and after OLT is high. A study by Krowka et al.8 identified a strong association between mortality and pre-OLT mean pulmonary artery pressure, documenting a mortality of 50% for mean pulmonary artery pressure 35-49 mmHg and 100% mortality for patients with a pre-OLT mean pulmonary artery pressure of 50 mmHg or more. Such patients may require aggressive optimisation with vasodilator agents such as prostaglandin E1 although poor reversibility of pulmonary hypertension may also be indicative of an increased risk in the perioperative course of liver transplantation.9

In addition to these specific cardiorespiratory complications, end stage liver disease is also frequently associated with renal impairment which may share the same pathological process as that causing the liver disease (for example, autoimmune disease) or may result from the hepatorenal syndrome. In this case it is thought to be due to renal hypoperfusion due to peripheral vasodilatation together with renal vasoconstriction as a result of activation of the renin-angiotensin aldosterone system, together with anti-diuretic hormone production. Careful fluid balance and adequate organ perfusion throughout the procedure should reduce the incidence of postoperative renal failure with a consequent impact on morbidity and mortality. Optimal cardiovascular monitoring is essential in limiting such problems.

In addition to these pathophysiological processes, the three major stages of OLT (pre-anhepatic, anhepatic and reperfusion phases) pose particular challenges in terms of anaesthetic management.

Pre-anhepatic Phase

Hypotension may result from temporary obstruction of venous return as a result of surgical manipulation of the liver. Transection of large varices and drainage of large quantities of ascitic fluid will contribute to significant fluid shifts. In addition there is a potential for significant haemorrhage even at this early stage.

Anhepatic Phase

Clamping of the inferior vena cava and portal vein reduce cardiac return. When used, veno-venous bypass facilitates the passage of venous blood from the lower body to return to the heart. Nevertheless, there may still be inadequate return of blood to satisfy the hyperdynamic system, and hypotension can result. Additionally, a reduced perfusion pressure can precipitate renal failure.

The use of side clamps during preservation of the vena cava for piggyback implantation allows continuation of a diminished inferior vena cava flow and improves cardiovascular stability during the anhepatic stage. This not only avoids total reliance upon collateral venous return, but also avoids the complications of complement and coagulation cascade activation following contact with foreign body materials which are thought to occur as a result of veno-venous bypass.

Reperfusion Phase

This is the phase of the operation which is associated with the most considerable cardiovascular instability. Immediately there is an increase in vascular space as the liver is initially reperfused resulting in a temporary reduction in venous return and cardiac output. Subsequently, over the following minutes, a period of instability known as the reperfusion syndrome can begin to exert its effect. (Defined as >30% decrease in mean systemic blood pressure for more than 1 minute during the first 5 minutes of reperfusion). In a six year retrospective review of anaesthetic experience with orthotopic liver transplantation in Hong Kong, the reperfusion syndrome was seen in 42% of recipients.10 This typically comprises severe hypotension, decreased heart rate, a significant reduction in systemic vascular resistance and an increase in pulmonary arterial pressure. It is thought that these changes are the result of a sudden release of cold, acidotic and hyperkalaemic fluid into the circulation. There may also be an associated myocardial dysfunction resulting from free oxygen radicals produced by xanthine oxidase which exert a cytotoxic effect. Xanthine oxidase is one of many mediators released by the ischaemic liver.11 The release of prostaglandins, kallikrein and leukotrienes into the systemic circulation also contribute to a decrease in cardiac output and may play a role in mediating systemic vasodilatation.9

The rapidity and clinical significance of these changes make effective cardiovascular monitoring an essential component of the anaesthetic management of patients undergoing orthotopic liver transplantation. Accurate representation of clinical events permits rapid anaesthetic management during this complicated procedure and is therefore anticipated to optimise the opportunity for a maximally successful outcome.

Requirements of a monitoring system

The ideal monitoring system would have many specific requirements, only some of which are achievable within the technological and physical constraints in which they are utilised. Nevertheless, the following list includes many of the key ideals for a cardiovascular monitoring system in clinical practice.

  • 1
    Accuracy. (Provision of correct readings)
  • 2
    Precision. (Adequate resolution to allow differentiation between readings and therefore correctly identify a change)
  • 3
    Rapid response time.
  • 4
    Continuous “real-time” updating of data
  • 5
    Reproducibility.
  • 6
    Operator independence.
  • 7
    Minimal risk to the patient.
  • 8
    Maximal provision of information.
  • 9
    Cost effectiveness.

A comparison of the pulmonary artery flotation catheter against transoesophageal echocardiography is shown in Table 1.

Table 1. Comparison of the Pulmonary Artery Flotation Catheter Against Transoesophageal Echocardiography
 PAFCTOE
  1. Abbreviation: LVEDP, Left Ventricular End Diastolic Pressure.

AccuracyGood. Traditionally considered gold standard. Possibly inaccurate immediately after caval clamping and reperfusion.Good, but requires training and time to estimate left ventricular filling pressures and cardiac output numerically. “Global” visual assessment very rapid.
PrecisionGoodGood, but relies on good view acquisition
Rapid response time/ Continuous dataPA pressure reading continuous and rapidly updated.Cardiac output calculation slow (intermittent thermodilution) and not continuous. (Continuous CO PAFC equipment available)Real time views continuously updated.Computer driven algorithms permit rapid calculation of pressure gradients and cardiac output.Dynamic appearance of cardiac structures instantaneous.
“Real Time” updatingPoorExcellent
ReproducibilityGoodGood19
Operator independentYesYes19
Minimal risk to patientRisks associated with venous cannulation, catheter flotation and wedging of PAFC.Low risk. Relatively non-invasive.
Maximal informationLimited to numerical measurement and calculated parameters.No direct pressure measurements, but able to directly visualise structural as well as dynamic abnormalities.
 Wedge pressure used to imply LVEDP can be misleading.Filling represented visually and calculations possible to derive volume, cardiac output and other parameters.
 Pressure potentially a poor surrogate for filling or wall tension.Pulmonary artery pressure difficult to assess in absence of tricuspid regurgitation
CostMonitors integrated into standard monitoring equipment. Moderate unit cost of PAFC.High set up cost, low unit cost. (cleaning of probe and protective sheath)

COMPLICATION COMPARISON OF PAFC VS. TOE

  1. Top of page
  2. Abstract
  3. PATHOGENESIS AND PHYSIOLOGY OF CARDIOVASCULAR INSTABILITY DURING ORTHOTOPIC LIVER TRANSPLANTATION
  4. COMPLICATION COMPARISON OF PAFC VS. TOE
  5. COMPARISON OF TOE TO ESTABLISHED PRACTICE
  6. SUMMARY
  7. REFERENCES

Although a considerable amount of literature pertaining to the use of PAFC and TOE is available (albeit outside of the proposed use in OLT), there is little with regard to the incidence of complications of these techniques. The lists in Table 2 consider the principle risks associated with each technique.

Table 2. Complication Comparison of PAFC vs. TOE
Complications of PAFCComplications of TOE
  • *

    Oesophageal varices are generally considered to be a relative contraindication to TOE. Evaluation of the relative risks and benefits of TOE vs. PAFC is essential for all cases, with specific consideration required to the grade of varices present and bleeding history in the context of the of the anticipated advantages of TOE. A Medline search failed to identify any published adverse events relating to oesophageal varices and the insertion and manipulation of trans-oesophageal echocardiography probes.

1) Associated risks of venous cannulationa) Dental trauma
 a) Haemorrhageb) Pharyngeal abrasion
 b) Arterial puncturec) Variceal bleeding*
 c) Arrhythmiad) Oesophageal rupture
 d) Myocardial puncture/rupturee) Recurrent laryngeal nerve injury
 e) Cardiac tamponadef) Autonomic disturbance
 f) Thoracic duct damageg) Increased gastro-oesophageal reflux
 g) Pneumothoraxh) Risk of microshock (less than PAFC)
 h) Infection (medium to longer term complication) 
2) Complications of pulmonary artery catheterisation 
 a) Arrhythmia 
 b) Myocardial puncture and cardiac tamponade 
 c) Knotting of PAFC 
 d) Pulmonary artery rupture 
 e) Right sided valvular damage 
 f) Risk of microshock 

COMPARISON OF TOE TO ESTABLISHED PRACTICE

  1. Top of page
  2. Abstract
  3. PATHOGENESIS AND PHYSIOLOGY OF CARDIOVASCULAR INSTABILITY DURING ORTHOTOPIC LIVER TRANSPLANTATION
  4. COMPLICATION COMPARISON OF PAFC VS. TOE
  5. COMPARISON OF TOE TO ESTABLISHED PRACTICE
  6. SUMMARY
  7. REFERENCES

Established practice utilises a PAFC for provision of cardiovascular data. Pulmonary arterial catheterisation was introduced in the early 1970′s and became widely accepted in clinical practice over the following decade. Indeed, it is commonly regarded as the gold standard against which all subsequent means of cardiac output measurement have been compared.

However, over the years doubt has been cast as to whether the use of the PAFC in the management of the critically ill patient improves overall patient outcome.12, 13 An observational study retrospectively studied 5,735 carefully matched critical care patients between 1989 and 1994, and concluded that right heart catheterisation was associated with increases in both mortality (odds ratio 1.24, 95% confidence interval 1.03 – 1.49) and resource consumption.14 Indeed, these results, together with a lack of prospective randomised controlled trials, prompted the organisation of a consensus conference on the use of the pulmonary artery catheter in Chicago in 1996.15 In summary, this concluded that the benefit of PAFC use was dependent predominantly upon patient selection and adequate expertise in its use. In the UK, the PAC-Man trial16 enrolled 1041 critically ill patients to randomisation for management with or without PAFC, and demonstrated no difference in hospital mortality and commented that efficacy studies would be required to ascertain whether specific groups of patients may benefit. Very recently the Acute Respiratory Distress Syndrome Clinical Trials Network17 published its findings for the use of PAFC in the context of acute lung injury and found no benefit in terms of survival or organ function despite an increased rate of complications compared to central venous catheter guided therapy. No studies to date are available to evaluate the outcome in patients undergoing OLT relating to the perioperative use of a PAFC, and would be unlikely to be adequately powered given the number of procedures being undertaken. Nevertheless, the general lack of overall benefit in critically ill patients does not form an encouraging picture for PAFC efficacy in OLT.

Although traditionally considered the gold standard, the accuracy of the PAFC has been questioned by a study comparing continuous with intermittent thermodilution cardiac output measurements during OLT, which suggested that there was considerable variation using both techniques immediately following caval clamping and reperfusion of the donor liver. This was thought to be a result of thermal noise as central and peripheral compartment temperatures equilibrate. Whilst continuous thermodilution appears to underestimate the rise in cardiac output at reperfusion (probably due to averaging algorithms), intermittent thermodilution when compared to bioimpedence appears to provide an overestimate.18

Transoesophageal echocardiography is becoming an increasingly popular imaging tool for real-time cardiac monitoring. The principle advantage of TOE is that real-time images provide immediate visual information about both the structural nature of the heart, and more importantly, its dynamic function. It is less adept at providing the numerical data which we are used to interpreting from PAFC's, but in reality, most of this data is used to infer dynamic changes within the cardiovascular system, which instead are directly visualised by TOE. Nevertheless, in order to aid objective assessment and comparison, numerical data can be calculated from TOE images, and when undertaken by the software within the TOE machine, still provides rapid results. In the critical care setting, a retrospective analysis of 108 non-cardiac critical care patients in whom TOE had been performed identified that the results of the TOE altered management in at least one third of patients, irrespective of the presence of a PAFC.19 This suggests that TOE can provide additional useful information to a PAFC. Because the reverse study does not appear to have been undertaken, it is difficult to determine that TOE might replace PAFC rather than provide exclusively additional information, and one must note that the benefit from these management changes was not assessed. However, because TOE allows direct visualisation of cardiac filling rather than pressure readings, which may be influenced by a large number of other factors (for example, intermittent positive pressure ventilation, pulmonary hypertension, valvular dysfunction and ventricular failure), it can therefore presumably provide a more meaningful interpretation of myocardial wall tension than PAFC pressure measurements.

A significant advantage of TOE is the identification of right ventricular failure by virtue of dynamic rather than the pressure changes which may be easily missed on PAFC measurement. It is not clear whether there is a strong relationship between central venous pressure, pulmonary artery pressure and right ventricular failure, which is probably because the compliance of the right ventricle is such that it may dilate significantly before pressure begins to rise. Nevertheless, the implication of Laplace's law makes it clear that once dilated, the contractile ability of the right ventricle is markedly reduced, and therefore the relative disability of the right ventricle may not be identified by PAFC until there is severe failure, being much more rapidly demonstrated by cardiac imaging. Right ventricular failure is of particular pathological importance during the reperfusion phase of liver transplantation, and TOE therefore holds a very significant advantage during the monitoring of this stage.

Whilst parameters derived and inferred from PAFC studies are able to give an interpretation of global myocardial function, there is no scope for identifying areas of myocardium which are performing less well. By contrast, TOE is capable of illustrating areas of regional wall dysfunction which would otherwise remain undiagnosed, yet not only indicate reduced overall performance, but may also represent areas of the myocardium susceptible to permanent damage. TOE also permits visualisation of septal movement and displacement which are key indicators of right ventricular overload and failure and which are likely to go undiagnosed by PAFC readings alone.

Although TOE does not provide directly measured pressure readings, an estimate of left ventricular filling pressure is calculable by a number of methods including multiple regression as reported by Mulvagh et al.20 In a comparison of TOE vs. PAFC by Dabaghi et al.21 TOE had a sensitivity and specificity of 96% and 90% respectively, with absolute pressure differences between the two techniques of 3 ± 3 mmHg. Similarly there was no significant difference between cardiac index values. In the same study the inter-observer variability for Doppler estimates of left ventricle filling pressure and cardiac index were 3.6 ± 0.7 mmHg and 0.12 ± 0.38 L.min-1.m-2 compared to an intra-observer variability of 3.4 ± 2.4 mmHg and 0.16 ± 0.25 L.min-1 .m-2 respectively. These figures suggest considerable reproducibility of TOE findings both by the same operator and between different operators, and suggest that calculated pressures may be a sufficient surrogate for directly measured parameters. In addition to this, a visual assessment of cardiac filling is considerably faster than PAFC readings.

Other advantageous features of TOE are firstly that it permits re-assessment of the patient's cardiopulmonary status immediately prior to surgery and is therefore able to identify any changes that may have occurred since being listed for OLT that may affect their suitability. Secondly, in centres utilising veno-venous bypass, the TOE probe may be used to assist in the placement of transcutaneous veno-venous bypass lines, as described by Planinsic et al.22 Insertion of such large bore cannulae is known to have significant morbidity and the potential for life-threatening complications.23

There is a potential role for TOE use in paediatric OLT which has yet to be adequately evaluated. Currently, the use of TOE in paediatric OLT is varied. Concern that there may be an increased risk of PAFC knotting in children provides encouragement for the use of TOE, whilst the diameter of the TOE probe itself may be a limiting factor, particularly with older technology mandating larger probes. Nevertheless, TOE does appear to have an established following in the anaesthetic management of small bowel transplantation and multi-visceral transplantation in the paediatric arena because of the markedly increased difficulty with line insertion following long term total parenteral nutrition provision. The skills and expertise required for TOE use are likely to be extended into the paediatric OLT field but as yet there appears to be little discussion as to whether this will confer an advantage.

TOE may provide ancillary and often unanticipated information. For example, Saada et al.24 observed the temporary opening of a foramen ovale following reperfusion and elevation of pulmonary arterial pressures prompting management of the pulmonary hypertension. Harley et al.25 describe the use of TOE in two patients with hypertrophic cardiomyopathy undergoing OLT in whom it was demonstrated that filling pressures by PAFC poorly reflected end diastolic volumes visualised on TOE. TOE may also be of benefit in the occasional situation in which PAFC is unable to be placed (for example, abnormal vascular anatomy and multiple previous cannulations for intravascular monitoring).

A major concern in advocating the use of TOE is the training required for competent scanning and interpretation of TOE images. Benjamin et al.26 undertook 100 intensivist TOE examinations on critical care patients under cardiological supervision and found that even during training stages TOE disagreed with PAFC in 55% of cases for assessment of intracardiac volume (filling) and 39% of cases for myocardial function, with the results of the TOE being considered by the cardiologist to be more accurate. They concluded that training intensivists in “limited-scope” TOE could be done rapidly and safely, and could yield information pertinent to management even in the early stages of skill acquisition. However, the American Society of Echocardiography does not differentiate full versus “limited-scope” skill levels, and recommends a training program involving 300 transthoracic echocardiographic examinations, 25 oesophageal intubations and 50 TOE examinations within a six month period, followed by the performance of 50-75 TOE's per year.17 These recommendations would restrict the use of TOE for OLT considerably.

One advantage of the PAFC over the TOE in the critical care setting is that once inserted, the PAFC can remain in situ allowing continuous or subsequent measurements, whereas the TOE requires reinsertion. However, in the setting of OLT, the TOE probe remains in place throughout the procedure. Since it is a relatively non-invasive procedure, the complication rate from re-insertion is likely to be low, but usually requires an unconscious or sedated patient to permit oesophageal intubation. Another problem specific to TOE is that movement of the operative field can affect the relative positions of the heart, oesophagus and stomach such that at certain times during the dissection of native liver steady images can be difficult to obtain.

SUMMARY

  1. Top of page
  2. Abstract
  3. PATHOGENESIS AND PHYSIOLOGY OF CARDIOVASCULAR INSTABILITY DURING ORTHOTOPIC LIVER TRANSPLANTATION
  4. COMPLICATION COMPARISON OF PAFC VS. TOE
  5. COMPARISON OF TOE TO ESTABLISHED PRACTICE
  6. SUMMARY
  7. REFERENCES

Both transthoracic echocardiography and TOE are evolving as important diagnostic tools within the Critical Care environment, and TOE has become an established monitoring tool in cardiac anaesthesia where the surgery itself may preclude the placement of a PAFC. TOE has many advantages which advocate its use certainly as an additional monitoring tool in liver anaesthesia, and potentially ultimately as a replacement for pulmonary artery catheterisation, although advantages in terms of long term patient outcome are yet to be evaluated.

The principle advantage of TOE over PAFC is direct visualisation of the heart in real time, allowing instantaneous assessments of the state of the cardiovascular system, changes in global and regional contractility and the rapid diagnosis of ventricular dilatation and failure.

It is clear that whilst training is a requirement for effective and accurate use of the TOE, clinically useful interpretations are possible even during the skill acquisition phase of TOE training.

Whilst both methods of cardiovascular monitoring provide information considered essential for the anaesthetic management of orthotopic liver transplantation, in the absence of evidence indicating a difference in patient outcome between the two techniques, the choice of monitoring tool remains controversial. In a climate of abating faith in the overall benefit of PAFC for the critically ill patient, the benefit in the context of orthotopic liver transplantation must be questioned. Anecdotally at least, TOE appears to provide significant advantages over PAFC particularly in terms of monitoring changes in cardiac dynamic function.

REFERENCES

  1. Top of page
  2. Abstract
  3. PATHOGENESIS AND PHYSIOLOGY OF CARDIOVASCULAR INSTABILITY DURING ORTHOTOPIC LIVER TRANSPLANTATION
  4. COMPLICATION COMPARISON OF PAFC VS. TOE
  5. COMPARISON OF TOE TO ESTABLISHED PRACTICE
  6. SUMMARY
  7. REFERENCES
  • 1
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  • 2
    Carey WD, Dumot JA, Pimentel RR, Barnes DS, Hobbs RE, Henderson JM, et al. The prevalence of coronary artery disease in liver transplant candidates over the age of 50. Transplantation 1995; 59: 859864.
  • 3
    Gordon T, Castelli WP, Hjortland MC, Kannel WB, Dawber TR. Predicting coronary heart disease in middle-aged and older persons: the Framingham Study. JAMA 1977; 238: 497499
  • 4
    Zetterman RK, Belle SH, Hoofnagle JH, Lawler S, Wei Y, Everhart J, et al. Age and liver transplantation: a report of the Liver Transplantation Database. Transplantation 1998; 66: 500506.
  • 5
    Laberge JM, Brandt ML, Lebecque P, Moulin D, Veykemans F, Paradis K, et al. Reversal of cirrhosis-related pulmonary shunting in two children by orthotopic liver transplantation. Transplantation 1992; 53: 11351138.
  • 6
    Hadengue A, Benhayoun MK, Lebrec D, Benhamou JP. Pulmonary hypertension complicating portal hypertension: prevalence and relation to splanchnic hemodynamics. Gastroenterology 1991; 100: 520528.
  • 7
    Gerlach H. Perioperative Management of Liver Transplantation., European Society of Anaesthesiologists. 2002.
  • 8
    Krowka MJ, Plevak DJ, Findlay JY, Rosen CB, Wiesner RH, Krom RA. Pulmonary haemodynamics and perioperative cardiopulmonary-related mortality inpatients with Portopulmonary hypertension undergoing liver transplantation. Liver Transplantation 2000; 6: 443450
  • 9
    Cheng EY, Woehlck HJ. Pulmonary artery hypertension complicating anesthesia for liver transplantation. Anesthesiology 1992; 77: 389392.
  • 10
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  • 11
    Ramsay MAE. Anesthesia considerations in liver transplantation, Recent Developments in Transplantation Medicine.
  • 12
    Gore JM, Goldberg RJ, Spodick DH, Alpert JS, Dalen JE. A community-wide assessment of the use of pulmonary artery catheters in patients with acute myocardial infarction. Chest 1987; 92: 721727.
  • 13
    Leibowitz AB. Perioperative pulmonary artery catheterization: what is the evidence that it improves outcome? J Cardiothorac Vasc Anesth 1998; 12: 12.
  • 14
    Connors AF, Jr, Speroff T, Dawson NV, Thomas C, Harrell FE Jr, Wagner D, et al. The effectiveness of right heart catheterization in the initial care of critically ill patients. SUPPORT Investigators. JAMA 1996; 276: 889897.
  • 15
    Pulmonary Artery Catheter Consensus conference: consensus statement. Crit Care Med 1997; 25: 910–;925.
  • 16
    Harvey S, Harrison DA, Singer M, Ashcroft J, Jones CM, Elbourne D, et al. Assessment of the clinical effectiveness of pulmonary artery catheters in management of patients in intensive care (PAC-Man): a randomised controlled trial. Lancet. 2005 Aug 6-12; 366(9484): 472477.
  • 17
    The National Heart, Lung, and Blood Institute Acute Respiratory Distress Syndrome (ARDS) Clinical Trials Network; Wheeler AP, Bernard GR, Thompson BT, Schoenfeld D, Wiedemann HP, deBoisblanc B, et al.. Pulmonary-Artery versus Central Venous Catheter to Guide Treatment of Acute Lung Injury. N Engl J Med 2006; 354: 22132224.
  • 18
    Bottiger BW, Sinner B, Motsch J, Bach A, Bauer H, Martin E. Continuous versus intermittent thermodilution cardiac output measurement during orthotopic liver transplantation. Anaesthesia 1997; 52: 207214.
  • 19
    Poelaert JI, Trouerbach J, De Buyzere M, Everaert J, Colardyn FA. Evaluation of transesophageal echocardiography as a diagnostic and therapeutic aid in a critical care setting. Chest 1995; 107: 774779.
  • 20
    Mulvagh S, Quinones MA, Kleiman NS, Cheirif J, Zoghbi WA. Estimation of left ventricular end-diastolic pressure from Doppler transmitral flow velocity in cardiac patients independent of systolic performance. J Am Coll Cardiol 1992; 20: 112119.
  • 21
    Dabaghi SF, Rokey R, Rivera JM, Saliba WI, Majid PA. Comparison of echocardiographic assessment of cardiac hemodynamics in the intensive care unit with right-sided cardiac catheterization. Am J Cardiol 1995; 76: 392395.
  • 22
    Planinsic RM, Nicolau-Raducu R, Caldwell JC, Aggarwal S, Hilmi I. Transesophageal Echocardiography-Guided Placement of Internal Jugular Percutaneous Venovenous Bypass Cannula in Orthotopic Liver Transplantation. Anesth Analg 2003; 97: 648649
  • 23
    Budd JM, Isaac JL, Bennett J, Freeman J. Morbidity and mortality associated with large-bore percutaneous venovenous bypass cannulation for 312 orthotopic liver transplantations. Liver Transpl 2001; 7: 359362
  • 24
    Saada M, Liu N, Cherqui D, Beydon L, Maurel C, Catoire P, et al. Opening of a foramen ovale during liver transplantation. The value of transesophageal echocardiography. Ann Fr Anesth Reanim 1990; 9: 412414.
  • 25
    Harley ID, Jones EF, Liu G, McCall PR, McNicol PL. Orthotopic liver transplantation in two patients with hypertrophic obstructive cardiomyopathy. Br J Anaesth 1996; 77: 675677.
  • 26
    Benjamin E, Griffin K, Leibowitz AB, Manasia A, Oropello JM, Geffroy V, et al. Goal-directed transesophageal echocardiography performed by intensivists to assess left ventricular function: comparison with pulmonary artery catheterization. J Cardiothorac Vasc Anesth 1998; 12: 1015.