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Disclaimer: Ashleigh Publishing UK (www.ashleighpublishing.co.uk) produces the scholarly publication, PRACTICAL ASPECTS of THORACIC ANAESTHESIA and Ashleigh Publishing Group USA (www.ashleighpublishing.org), is an independent publisher for fiction and nonfiction books and are two different entities not associated with each other.

CONTENTS

Sample Text

DECORTICATION

Empyema – natural history

Empyema is pus in the pleural space. It must be emphasised that when it follows pulmonary resection the presumption has to be that it is associated with a broncho-pleural fistula (q.v.). That apart empyema is usually caused by an infection from the lung spreading into the pleural cavity and provided it is adequately drained early on, it will often resolve spontaneously. If allowed to develop, however, a thick walled abscess forms which is most commonly basal. This wall is fibrinous and is bounded by visceral and parietal pleura. As the fibrin contracts the lung can become severely constricted and, in the absence of treatment, permanently damaged.

The pleura

Parietal pleura is normally quite substantial and fairly loosely attached to the chest wall (though firmly adherent to the diaphragm), but the visceral pleura is of cellular thickness and cannot, under any circumstances, be stripped from the lung.

• • SURGICAL MANAGEMENT

    • So called decortication is, therefore, two processes - firstly a pleurectomy which includes the removal of abscess wall and parietal pleura from the chest wall and, secondly, a genuine decortication which is the stripping of the thickened fibrinous wall of the rest of the abscess cavity from the visceral pleura covering the lung. Supposedly this stripping is easiest to perform six weeks after the initial infection but, in practice, the earlier the better. As the peeling proceeds, the lung should, hopefully, re-expand. It is rare for the end stage of a decortication to be aesthetically pleasing. Total stripping is seldom possible and there are often extensive air leaks of which it is usually only possible to stop the most major ones. If a lobe has been seriously damaged by the infection lobectomy may have to be performed at the same time. Post operatively the air leaks will normally seal up quite quickly and resolution of the remaining fibrin deposits usually occurs over the succeeding months.

    • Tuberculous empyema Should the primary infection be tuberculous the visceral pleura is destroyed by the disease process and the lung is involved directly, making the stripping extremely difficult and tedious.

  • ANAESTHETIC MANAGEMENT POINTS

    • Decortication should be set up as for any other thoracotomy (Chapter 6) and the operation is normally carried out with the lung "up".

Lung isolation

The importance of a correctly placed and managed double-lumen tube is often highlighted by this operation:

Air leaks Air leaks from the raw lung surface can be a major problem; sometimes so much so that it becomes necessary to go on to one side in order to maintain ventilation (a bad moment to discover that the patient cannot cope on one lung).

Pulmonary abscess A previously unsuspected pulmonary abscess can suddenly drain into the bronchial tree.

Catheter mount In this, as in any thoracotomy, ensure that the double catheter mount runs downhill away from the patient - more than once a large abscess has been known to discharge up one side of the mount and pour back down the other side into the healthy lung, which rather defeats the reason for placing a DLT in the first place.

Blood loss

Blood loss can be extensive - four litres would not be uncommon - characterised by a steady ooze with multiple large, saturated swabs packed into the chest cavity.

Re-expansion

Sometimes a lobe that has been collapsed for a long time may be reluctant to re-inflate at the end of the operation; if so, pre-oxygenate the patient and institute hand ventilation. Temporarily disconnect and clamp off the dependent lung and squeeze the bag hard in an attempt to bring up the reluctant lobe. The pressures involved may be very high but the other lung is protected and the upper lung which is being subjected to the insult is, of course, under direct observation.

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(updated March 23rd, 2013)

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ISBN: 978 0 9537378 4 0

Classification:Medical

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Updates (Most recent: September 2011)

Several relevant writings have emerged since the publication of ‘Practical Aspects of Thoracic Anaesthesia’ (PATA). The most significant of these are given below, together with brief comments:

• 1. Michelet P, Guervilly C, Hélaine A et al. Adding ketamine to morphine for patient-controlled analgesia after thoracic surgery: influence on morphine consumption, respiratory function, and nocturnal desaturation. Br J Anaesth 2007; 99: 396-403

  2. This study shows a reduced requirement for opiate and a corresponding improvement in respiratory function. It is reasonable to suppose that similar advantages would apply in the case of continuous IV infusion (PATA p130-1). Presumably the dose of ketamine is too low for hallucinations to be a problem.

  3. Christie IW, McCabe S. Major complications of epidural analgesia after surgery: results of a six-year survey. Anaesthesia 2007; 62: 335-41

  4. This is a retrospective survey of general and orthopaedic surgical patients but appears extremely thorough. There were 8,100 epidurals of all types. Apparently (personal enquiry) around 60% were thoracic. 12 major complications occurred of which 9 related to thoracic epidural analgesia and 3 to lumbar epidural. This represents a complication rate of one per 540 thoracic epidural insertions which seems a sobering statistic (PATA p130-1).

  5. Galvin I, Drummond GB, Nirmalan M. Distribution of blood flow in the lung: gravity is not the only factor. Br J Anaesth 2007 98: 420-8

  6. This review makes compulsive reading. It blows a substantial hole in West's Zone Theory and only stops just short of demolishing it completely. The implications for ITU patients with pulmonary exchange problems are fairly fully discussed but there doesn't appear to be anything about thoracic anaesthesia (with the effects of pulmonary hypotension or the open chest for example); certainly a challenge worth taking up (PATA p83).

  7. Leong LMC, Chatterjee S, Gao F. The effect of positive end expiratory pressure on the respiratory profile during one-lung ventilation for thoracotomy. Anaesthesia 2007; 62: 23-6

  8. This study supports the thesis that PEEP offers no general advantage in the conduct of thoracic anaesthesia. However, the pressure should have been measured at the tip of the tube and there are too few cases for a proper matching of the groups. It could usefully be repeated (PATA pp viii, 65,68,85).

  9. Conacher ID, Velasquez H, Snowden C. Significance of tricuspid valve dysfunction as a consequence of one-lung ventilation. Br J Anaesth 2008; 101 (2): 283

  10. A short letter reminding us that the insertion of a double-lumen tube causes pulmonary hypertension. This leads to tricuspid regurgitation which protects the pulmonary vascular bed. Should the mechanism become overloaded (particularly likely during pneumonectomy) damage could result to the bed leading to Adult Respiratory Distress Syndrome. Whilst being largely hypothetical it does appear a highly plausible idea and should certainly be added to the ARDS list on page 73 of PATA. The letter includes half a dozen informative and not widely quoted references.

  11. Sear JW, Foëx P. Recommendations on perioperative beta-blockers: differing guidelines: so what should the clinician do? Br J Anaesth 2010; 104 (3): 273-5

  12. This editorial, which merits careful perusal, discusses the implications of two recent sets of recommendations, the first (from August 2009) by the European Society of Cardiology and the second (November 2009) by the American College of Cardiology/American Heart Association. Both take into consideration the Perioperative Ischaemia Study Evaluation Trial (POISE) (Lancet, 2008; 371: 1839-47) as well as other work. POISE concerns a prospective trial in which metoprolol was administered peri-operatively to 8,351 hypertensive patients undergoing non-cardiac surgery, starting 2-4 hours before induction. There was a significant drop in the number of deaths over 30 days relating mainly to a reduction in the number of myocardial infarctions. However, this concealed an increase in the mortality due to cerebro-vascular incidents. It seems that many of the patients who suffered this fate received a relative overdose which can certainly produce refractory hypotension under anaesthesia. PATA (p. 57) advocates the use of Β blockers (atenolol, in fact) partly because they are effective and partly because some of the alternatives (notably angiotensin-11 receptor antagonists) can be particularly troublesome. Perhaps it should be made clearer in the text that the intention is not to flatten the cardiovascular response to laryngoscopy and surgical stimulation completely but to smooth it, which means varying the dose according to the individual patient response. This would seem to be compatible with the main implications of the BJA editorial.

1. Lee KG. Anaesthetic equipment for thoracic surgery. Anaesthesia and Intensive Care Medicine 2008; 9 (12): 538-41

2. This helpful review article looks at the types of endobronchial apparatus currently available together with the ways in which they are used. The same volume deals with several other aspects of thoracic anaesthesia, summaries of which may be found at www.anaesthesiajournal.co.uk

3. Rucklidge M, Sanders D, Martin A. Anaesthesia for minimally invasive oesophagectomy. Continuing Education in Anaesthesia, Critical Care and Pain 2010; 10(2): 43-7

4. Page 101 of PATA (Oesophageal surgery) mentions the existence of the minimally invasive technique for oesophagectomy with little additional comment but 'astonishment' might have been an appropriate one. Like flying a 747 upside down across the Atlantic the fact that this stunt is possible isn't a reason for performing it. Readers are invited to draw their own conclusion from the article.

   1. Rozé H, Lafargue M, Batoz H et al. Pressure-controlled ventilation and intrabronchial pressure during one-lung ventilation. Br J Anaesth 2010; 105: 377-81

   2. Pages 68 and 69 of PATA deal with the relative merits of volume controlled and pressure controlled ventilation (VCV v PCV). It speculates that ventilator-induced lung injury (VILI) is unlikely when a double-lumen tube is in use and the study by Rozé and colleagues strongly supports that view. It is very helpful to be able to quantify leaks accurately during pulmonary surgery. That is only possible with VCV and these results therefore swing the argument back in favour of volume control in this particular scenario.

   3. Ng A, Swanevelder J. Hypoxaemia associated with one-lung anaesthesia: new discoveries in ventilation and perfusion. Br J Anaesth 2011; 106 (6): 761-3

   4. This editorial does what it says on the box, even to the extent of leaving out some not-so-new discoveries. However it is a very useful survey and contains many interesting references which otherwise might easily slip under the radar of the busy clinician.

Sugammadex

At the moment the impact of sugammadex remains uncertain, not least because of its price. Also, new drugs often turn out to have unexpected properties or side effects which make them less desirable than originally supposed. Some thoracic anaesthetic manoeuvres call for an extremely short period of profound muscle relaxation (see PATA p. 92, for example) and it is difficult to see how this could be achieved with a sequence of non-depolarising relaxant and sugammadex. It is to be hoped that suxamethonium will be retained for niche applications and certainly it is too early to write it into history yet.

The position of Cisatracurium might also be called into question because of its one and only significant drawback: its speed of onset is fairly slow. Whilst in reality this is of little moment with the type of case for which it tends to be employed, it would be a great pity if the greater utility of other non-depolarisers resulting from the introduction of sugammadex marginalised a wonderfully "clean" and predictable drug

VALETE

It is good to see the resurgence of interest in thoracic anaesthesia after decades of neglect. All but one of the 26 references mentioned by Dr. Ng in his editorial (10 above) post-date the writing of Practical Aspects of Thoracic Anaesthesia, for example. It is time for the author, now retired for some years, to move on. PATA follows a logical format eminently suitable for the extensive revision which it now needs and I should be interested to hear from anybody that would interested in doing so. This website will be maintained for as long as possible but as of 15th September, 2011, it's clinical content will no longer be updated.

Alan Seymour.

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