Modern Haemodynamic Monitoring: Out With The Old
Author: Dr Karen Stuart-Smith, Consultant Anaesthetist, Glan Clwyd Hospital, Denbighshire, Wales.

Winter Scientific Meeting 10th-12th January 2007
Queen Elizabeth II Conference Centre, Westminster, London

Lot’s In A Name: Do We Need To Change The Name Of Our Speciality?
Author: Dr. L.D. Mishra MD, Reader in Anaesthesiology & I/C Division of Neuroanaesthesia, Institute of Medical Sciences, Banaras Hindu University, Varasi – 221005, India. Email: ldmishra@rediffmail.com. Written originally for the World Anaesthetic Society.

Modern Haemodynamic Monitoring: Out With The Old
Author: Dr Karen Stuart-Smith, Consultant Anaesthetist, Glan Clwyd Hospital, Denbighshire, Wales.

The theme for this issue of Anaesthesia Product News is monitoring. This represents a good opportunity to review a complex and controversial area: the role of haemodynamic monitoring in major surgery and septic shock. In the course of writing this article, I talked to several of the manufacturers of haemodynamic monitoring equipment (at the European Intensive Care Society Meeting), and read a lot more literature than I had originally intended, reflecting the minefield I had inadvertently wandered into. The main conclusions I came to are these: 1) In major surgery, early fluid (preferably pre-operatively) is vital for improved patient outcome. 2) By contrast, in septic shock, macromanagement of global haemodynamic parameters doesn’t really help and never has, unless there is additional micromanagement of the resistance arterioles and distal vessels, to maintain aerobic metabolism, and 3) consequently, the minimally invasive haemodynamic monitors currently on the market are perfect for point 2), but additional (as yet not invented) monitoring, never mind therapy, is required in situation 3).

These are very difficult areas to join together in one article, not to mention contentious, so for this issue of APN, I am going to address haemodynamic monitoring for major surgery, and leave septic shock till next time. In practice this means a discussion of standard CVP monitoring in comparison to the CardioQ oesophageal Doppler, and a similar discussion of the pulmonary artery catheter in relation to the LiDCO plus™ system. Anyone desperate to know about PiCCO™ will have to wait a few months until the next APN.

Fluid balance has always been a fraught issue in surgical patients. At least, it has been fraught for the anaesthetist. The surgeon, on the whole, remains happily unaware, on the principle that ignorance is bliss. We have all been presented with the surgical patient at 2am, who has been ‘going off’ for several hours, and has only a pink venflon, placed in hope rather than expectation, in the antecubital fossa, to show for it. A recent assessment by the Improving Surgical Outcomes Group¹ noted that 50% of deaths within 30 days of surgery occurred in patients who had never been admitted to an Intensive Care area, i.e., management was entirely ward-based. This report specifically identified inadequate peri-operative fluid management as a contributor to poor surgical outcome. The rot begins pre-operatively, when the half-starved elderly patient with multiple co-morbidities, an enthusiastic bowel prep, and their daily dose of furosemide and/or ACE inhibitor on board, arrives in the anaesthetic room. Normal electrolyte values at this juncture may be a greater reflection of the body’s capacity to disguise deficits through ion shifts in the short term, rather than an indicator that all is well. The anaesthetist must now play catch-up.

A very recent study of the effect of intra-operative fluid optimisation via oesophageal Doppler (CardioQ™, Deltex Medical) showed that patients whose fluid balance was determined by oesophageal Doppler had improved cardiac indices at the end of the procedure as compared with those whose intravenous therapy was determined by more conventional means². Surprisingly, both groups received the same overall fluid load. The key difference, as identified by the authors, was that the Doppler group received nearly half of their total intraoperative fluid boluses in the first quarter of the surgical time, whereas in the conventional group fluid boluses were spread throughout the operation. A similar study also found that, apart from a slight difference in colloid administration, total fluid given intraoperatively was the same in the conventionally managed and the Doppler groups³. Both groups even had the same average CVP at the end of the operation. Nevertheless, the Doppler-guided patients had better cardiac indices and shorter hospital stays. The message of both these studies is that early well-informed fluid administration makes catch up possible.

What of the sick surgical patient who arrives in theatre dehydrated and for whom the urgency of operation and/or the type of surgery (e.g. perforated bowel with peritonitis) make early catch up impossible? Haemodynamic management of such patients requires a high level of oxygen transport and delivery to peripheral tissues. Shoemaker’s classic paper on the issue, recommending an oxygen delivery goal of at least 600ml/minute/m2 remains the standard⁴.

Using these parameters, Bennett’s group at St George’s Hospital developed the concept of goal-directed therapy (i.e. the goal was an oxygen delivery index (DO2I) of 600ml/minute/m2) in patients admitted to ITU who had undergone major surgery and were at high risk of complications⁵. In the Bennett study, patients in the control arm received colloid boluses (250 mls) to produce a sustained rise in CVP of 2mmHg (‘conventional therapy’), whereas in the closely matched trial group, colloid was used to produce a sustained increase in stroke volume: a fundamentally different parameter. In addition the trial arm received dopexamine as necessary to achieve a DO2I of >600. Rather than place a pulmonary artery catheter to calculate stroke volume, the less invasive LiDCO plus system was used (of which more in a moment). The clinical trial was stopped early because using stroke volume as a means of improving DO2I (the trial group) resulted in significantly fewer post-operative complications and earlier hospital discharge than relying on CVP alone. Mean ITU stay was not altered, probably because of the small number of patients involved (100).

Why was the LiDCO system used in these patients to monitor and manage improvements in stroke volume, as opposed to the pulmonary artery catheter? The pulmonary artery or ‘Swan-Ganz’ catheter was invented by Dr Jeremy Swan and his junior colleague, William Ganz, in the late 1960s⁶. It was developed from the Fogarty embolectomy catheter. Dr Swan passed away only recently, in 2005, having made many substantial contributions to cardiology. Many of these important observations, particularly in the 1970s and 80s, were made using his pulmonary artery catheter.

There is no question that in skilled hands, this haemodynamic monitor is a very accurate guide to cardiac output and related indices, hence its continuing status as the gold standard. However, it is worth reinforcing the fact that Swan was a cardiologist, not an intensivist, and the type of haemodynamic variables of interest in heart failure are not necessarily the same as those of interest in septic shock, because the physiology of the two are completely different. The result was that a good cardiology tool got hijacked by intensive care where it did nobody much good, as the wrong variables were being treated. Add to this that the average ITU is full of half-trained juniors putting in pulmonary artery catheters late at night, where the catheters either: 1) miss the heart altogether and end up wedged in the pleura, 2) do get into the heart, but never reach their destination and wander aimlessly in the right ventricle, 3) get snagged on something else that makes them impossible to remove – this includes pacemaker wires, CVP lines, and mitral valves, especially regurgitant ones, or 4) do finally reach the pulmonary artery to show an impressive wedge pressure once and then never wedges again in spite of endless fiddling. You’ve all been there. Because of these complications, and because of the lack of evidence that pulmonary artery catheters improve outcome, these devices are quietly disappearing from clinical use⁷.

This still leaves the problem of the high-risk post-operative patient, who, as we have seen, has been clearly demonstrated to require an optimal stroke volume and DO2I to reduce complications and improve recovery. The LiDCO plus™ system, invented by Dr Terry O’Brien, is a less-invasive alternative to the pulmonary artery catheter. The true business end of the system is a continuous cardiac output monitor (PulseCO™) which can determine cardiac output via continuous analysis of the arterial waveform detected at the peripheral arterial line. Because of the manner in which the software performs the analysis, ‘damped’ arterial traces can still be analysed, within reason. The ‘LiDCO’™ part of the system refers to calibration of the software in the individual patient. A small dose of lithium chloride is injected into the central venous catheter (or peripheral line) and a lithium concentration-time curve is constructed by withdrawing blood past a lithium sensor attached to the arterial line.

The advantage of the system is that it uses two items, the central line and the arterial line, which will have been inserted in theatre anyway. It is also user-friendly, avoiding the frailties of junior SHOs. It does require re-calibration by the lithium technique every eight hours, but a well-trained ITU nurse can easily achieve this. As a measure of cardiac output and derived indices it is well validated. The most attractive aspect of the system, however, is the ability to programme cardiovascular targets for an individual patient into the software. This then appears as a target on the screen, and indicates how far therapy is from achieving this target. As interventions are made, progress towards ideal parameters can be visualised. This is goal-directed therapy in its most literal sense. The real question is whether the targets we set are the right ones, so there is definitely a need for a large multi-centre trial.

It is probably time to question the usefulness measurement of central venous pressure in the management of surgical patients. Central venous pressure is the best guide to fluid administration, right? In fact, dead wrong. CVP monitoring as a guide to fluid administration makes a fundamental assumption, never proven, that a preload that is good for the right ventricle is good for the left ventricle as well. Even a brief pause to consider the thicker left ventricular wall, and the far higher resistance it has to pump blood against, makes it clear that this is a dangerous assumption. Giving a fluid bolus will always raise CVP, in much the same way as filling a balloon with water will always raise the pressure inside the balloon. It does not necessarily mean that the patient needed the fluid in the first place. Cardiac output is primarily a function of left ventricular stroke volume.

Big rises in CVP in response to fluid boluses may be temporarily satisfying, but it presents the left ventricle with such a large preload that it is eventually knocked off the edge of the Frank-Starling curve and stroke volume actually starts to decline. Like the water-filled balloon, too much fluid will eventually make the patient go pop. For this reason it has been recommended that information from a CVP line should always be interpreted in the light of additional information from a cardiac output monitor⁸. I suspect, though can’t prove, that the many earlier studies that have recommended perioperative fluid restriction to improve outcome (running the patient dry) have mainly succeeded by avoiding overzealous use of the CVP as a guide to fluid administration⁹.

The advantage of new intra-operative haemodynamic monitors is that they eliminate the need for central venous pressure measurement altogether. Stroke volume, in terms of both absolute value and beat-to-beat variability, is a much more accurate indicator of the need for intravenous fluid administration than central venous pressure. There is a good physiological case for eliminating the use of CVP to guide therapy altogether, although the central venous line is of course required for drug administration. In its place the CardioQ™ oesophageal Doppler could be used in those patients vulnerable to dehydration but who are returning to ordinary wards post-operatively: elective orthopaedic patients, major gynaecology etc. For sicker patients requiring more complex monitoring, and in whom an arterial line and a central line are normally inserted, the LiDCO™ plus system is more appropriate than the pulmonary artery catheter. It seems that in the 21st Century, we finally have the sort of monitoring we need for really ill surgical patients. The initial capital outlay is easily justified by fewer post-operative complications and shorter hospital stay. All we need now is a full understanding of the pathophysiology of the disease process, which will take a lot longer…. (see next issue).

Declaration of interests.
The author would like to thank Dr Graham Lowe of Deltex Medical and Dr Terry O’Brien of LiDCO for talking to her about their products and providing some of the literature used in this article. The author would also like to point out that these are assessments of available technology for a trade magazine (Anaesthesia Product News) and she wasn’t paid a bean by either company to say any of it, so don’t write in and complain. Constructive comments only please.

References

1. Improving Surgical Outcomes Group. Modernising care for patients undergoing major surgery. June 2005
2. Noblett SE, Snowdon CP, Shenton BK, Horgon AF. Randomised clinical trial assessing the effect of Doppler-optimized fluid management on outcome after elective colorectal resection. Br J Surg 2006; 93:1069-76
3. Wakeling HG, McFall MR, Jenkins CS, Woods WGA, Miles WFA, Barclay GR, Fleming SC. Intraoperative oesophageal Doppler guided fluid management shortens postoperative hospital stay after major bowel surgery. Br J Anaes 2005;95:634-42
4. Shoemaker WC, Appel PL, Kram HB, Waxman K, Lee TS. Prospective trial of supranormal values of survivors as therapeutic goals in high-risk surgical patients. Chest 1988;94:1176-86
5. Pearse R, Dawson D, Fawcett J, Rhodes A, Grounds RM, Bennett ED. Early goal- directed therapy after major surgery reduces complications and duration of hospital stay. A randomised, controlled trial [ISRCTN38797445] Critical Care 2005;9:R687-93
6. Swan HJC, Ganz W, Forrester J, Marcus H, Diamond G, Chonette D. Catheterization of the heart in man with use of a flow-directed balloon-tipped catheter. N Engl J Med 1970;283:447-51
7. Harvey S, Stevens K, Harrison D, Young D, Brampton W, McCabe C, Singer M, Rowan K. An evaluation of the clinical and cost-effectiveness of pulmonary artery catheters in patient management in intensive care: a systematic review and a randomised controlled trial. Health Technol Assess 2006;10:No. 29
8. Magder S. Central venous pressure: a useful but not so simple measurement. Crit Care Med 2006; 64:2224-7
9. Lobo DN, Macafee DAL, Allison SP. How perioperative fluid balance influences postoperative outcomes. Best Pract Res Clin Anesthsiol 2006;20:439-55

Winter Scientific Meeting 10th-12th January 2007
Queen Elizabeth II Conference Centre, Westminster, London

Winter Scientific Meeting 2007 – Programme WSM 2007 is the first scientific meeting of the AAGBI’s 75th anniversary year. A popular meeting, it comprises a programme of scientific and clinical practice and an entertaining modicum of history. As detailed below, the first day features two parallel streams of ‘Core Topics’ and ‘Best Practice’ lectures delivered by national experts. Day two commences with a discussion of current ethical issues, while later in the day brings a change from convention, as the AAGBI celebrate their anniversary with a series of talks on the past, present and future role of the AAGBI. The final day starts with the specialist societies, followed by the 2007 GE Healthcare Lecture. The meeting is scheduled to close with an extremely topical debate on ‘patient death, manslaughter charges and criminal proceedings against doctors’, which is sure to hold all those attending to the final curtain. Plus there is the trade exhibition, workshops, satellite symposiums and not forgetting, the social side of the event.
Wednesday 10th January Core Topics Acute postoperative pain Burns and bangs Interhospital transfer Emergencies in theatre The liver, anaesthesia and surgery Best Practice The difficult paediatric airway Anaesthesia for laparotomy in the elderly patient Lower limb joint replacement The diabetic patient Emergency Caesarean section	Friday 12th January Scientific Sessions ACTA/OAA: The Parturient With Cardiac Disease Setting the scene The disease spectrum Who needs to be referred? Analgesia and anaesthesia for labour and delivery The GE Healthcare Lecture – From Servant to Master Survival Debate – ‘Criminal charges are always inappropriate when a doctor’s mistake leads to death.’
Thursday 11th January Scientific Sessions Ethics Boys: Clinical Ethics In Practice The truth, the whole truth and nothing but the truth – is lying ever right in medicine? Pandemic flu: a bioethical challenge Clinical ethics – life at the sharp end AAGBI 75 – The Last 75 Years And The Next 75 Years – A brief history of the AAGBI What did the anaesthestists ever do for us? The AAGBI and anaesthesia in the developing world Journals, publishing and anaesthesia in the next 75 years Science and anaesthesia in the next 75 years

Lot’s In A Name: Do We Need To Change The Name Of Our Speciality?
Author: Dr. L.D. Mishra MD, Reader in Anaesthesiology & I/C Division of Neuroanaesthesia, Institute of Medical Sciences, Banaras Hindu University, Varasi – 221005, India. Email: ldmishra@rediffmail.com. Written originally for the World Anaesthetic Society.

I will begin my deliberation by reminding you of the various names with which our speciality and its practitioners were called until the recent past. Some would call it “Anaesthesia” and others as “Anaesthetics”. Accordingly, we the practitioners of the speciality were called “Anaesthetists”. Some (including even a few anaesthesia colleagues) will go to the extent of calling us Anaesthesists. I have still not forgotten the days when members of the public, including some of our nonanaesthetist colleagues, would call us “Anaesthetics”, as if we were a bottle of ether or halothane.

On analysing the cause of this misunderstanding, we came to realise that this can largely be attributed to the words “Anaesthesia, Anaesthetists and Anaesthetics” themselves.

These being relatively difficult words to pronounce were also difficult to understand. Yet, at least in part, this was also due to a lack of awareness and probably a lack of interest on the part of the public in our speciality and in us. This can be traced back to our historically less dominant clinical and academic role.

I, being a strong proponent of pro-active undergraduate teaching of our speciality1, would like to suggest that adequately taught new medical graduates who are well aware of our crucial roles may well act as our ambassadors to the masses, including among the members of the medical fraternity^1,2.

The word “Anaesthesiology” emphasising that the speciality is concerned with the “science and practice of anaesthesia”, is a more meaningful and respectful name. So is the word “Anaesthesiologists” which refers to the “physicians who practice anaesthesia” after specialising in it. Surely, these appear more appropriate terms.

Moreover, the term anaesthesiologist helps to differentiate us from nonphysician (non-medical) anaesthetists. It is within this context that I would like to emphasize here that the practice of licensing and permitting non-physicians to work as anaesthetists in some countries (some Scandinavian, Eastern European, Australasian countries and the United States) is detrimental to the cause of anaesthesiology.

In my view this trend should be stopped as soon as possible.

On the other hand, we have come to understand that anaesthesiology itself is not a very appropriate term for two main reasons:

1. In itself it is a fairly difficult word to pronounce (and sometimes to understand).
2. It is an incomplete word.

I will not forget how the Chief Minister of Orissa pronounced the word. Although he could speak the word “Anaesthesiology” with some difficulty, he could not complete speaking the word “Anaesthesiologists” without stopping at 2 or 3 places. He pronounced it as “Anaes-thes-iologists”, even though the said Chief Minister is highly educated and very conversant in English.

In recent years, the speciality has emerged as a multifaceted clinical discipline occupying a “central role in overall patient care”. Anaesthesiologists are now playing a major role in the pre-, intra- and postoperative care of surgical patients. They work in the intensive care units as intensivists and as key consultants/specialists in the management of critically ill patients throughout the hospital. Their role in the non-surgical management of chronic and intractable pain is also commendable.

Trauma care and the medical management of natural calamities, disasters and other emergency situations are a few other emerging roles for us. As “anaesthesiology” is inadequate to describe our established and emerging roles, we need to consider a more appropriate term for our speciality, which gives a more complete meaning to it. This idea is not totally new. There have been serious attempts to highlight the emerging sub-specialities of anaesthesiology and correlate the parent speciality with major sub-specialities.³

Here it is worth considering a few other often used terms, such as “Anaesthesiology and Critical Care,” “Anaesthesiology and Intensive care,” “Anaesthesiology and Re-animation” or “Anaesthesiology and Resuscitation.” These and a few other similar terms have spontaneously come in use during the past few years, but the word “Anaesthesiology” remains a part of all these terms; so does the word “Anaesthesiologists”. To me, as also suggested by Hoellerich⁴, “acute care medicine” could be a more acceptable and versatile term.

Yet, it falls short of the total nature of our speciality as it does not include “chronic pain management”.

In this regard, the term “perioperative, critical and pain medicine” could be a more befitting name for our speciality. It appears long but carries an appropriate and easily understandable meaning. Moreover, it is expected to bring more respectability to our speciality as we all know that “there is a lot in the name”.

It will not be out of place to mention a word of caution here. Just giving a new name to our speciality is not sufficient. We have to excel and perform second to none in the given areas of patient care. We must be adequately trained and experienced in the areas concerned. To meet these objectives, we need to continuously update our undergraduate, postgraduate and super-speciality teaching and training and demonstrate our academic and research potential.⁵ We may have to consider including mandatory rotations to most medical departments during postgraduate training and the respective superspeciality medical and surgical departments during superspeciality training.

Naturally this is not the end.

I do, however, sincerely wish that this will initiate a serious dialogue on the issue and hope that it will not be an endless dialogue.

References

1. Mishra LD. Undergraduate anaesthesia education: Philosophy. Editorial I, Ind J Anaesth 2002; 46(5): 344-5.
2. Kotur PF, Goudar SS. Undergraduate anaesthesia education: Principles and paradigms. Editorial II, Ind J Anaesth 2002; 46(5): 346.
3. Vaughan RW, Vaughan MS, Aluise J. Anaesthesiologists in North Carolina: a survey reflecting emerging subspecialization. J Clin Anesth. 1989; 1(4): 313-9.
4. Hoellerich VL. Acute care medicine. A community hospital practice. Anesthesiol Clin North America. 2000; 18(3): 539-50.
5. Miller RD. The place of research and the role of academic anaesthetists in anaesthetic departments. Best Pract Res Clin Anaesthesiol. 2002; 16(3): 353-70.

Source of article: World Anaesthesia Online.

Please note the views expressed in this article are those of the author and not necessarily those of the WFSA or the World Anaesthetic Society or Anaesthesia Product News.