Anaesthesia vol24 no 3 JuZy I969

Anaesthesia for bronchoscopic photography M. Morgan Jean Lumley P. W. McCormick P. Stradling

In the Chest Clinic at Hammersmith Hospital, it is the general practice to record bronchoscopic findings by photography. This involves the use of a modified bronchoscope which is described below. Anaesthetic require- ments are the same as for any other bronchoscopic technique, with the following additional problems : complete paralysis must be maintained during photography and the procedure is longer than routine broncho- scopic examination. The bronchoscope is not a true ventilation broncho- scope, only a small part of the cross-sectional area being available for ventilation; the resistance to gas flow is therefore high. The purpose of this study was to determine if adequate ventilation and oxygenation could be maintained throughout the procedure using manual compression of a reservoir bag in a circle system, or alternatively, a cuirass ventilator.

The bronchoscope

The bronchoscope (figures 1-4) consists of an outer sheath with removable forward or lateral viewing teIescope/lighting systems *. It is designed to be used with the telescope constantly in position so that maximum visibility and photography are possible at all stages of the examination. The sheath (figure 1) is a simple, parallel-sided stainless steel tube with side holes in the distal end to ensure distribution of gases to both lungs. As this sheath has no integral lighting system, it is convenient to introduce it with the telescope/lighting unit in place. During introduction, this unit is not fully inserted into the sheath so that the leading tip of the sheath can be seen anteriorly in the telescopic field of vision, so facilitating the manoeuvre. *The system here described, with its proximal fighting facility, was designed by M. Fourestier, A. Gladu and J. VulmiPre in France. It is manufactured by Etablissements Groux, 35 Rue des Coquelicots, Athis-Mons (S & 0), France andpatents are held by the Centre National de la Recherche Scientifique. The plain sheath provided was modified to P.S's specifications by the instrument engineers of Hammersmith Hospital to allow the ventilation here described: the ventifation tube and side holes are the main features of this modification.

M. Morgan, MB, BS, FFARCS, (now Consultant Anaesthetist, Tottenham Group of Hospitals, London N l a , Jean Lumley, MB, BS, FFARCS, P. W. McCormick, MB, ChB, FFARCS, (now Consultant Anaesthetist. St George's Hospital, London S W l ) , P. Stradiing, MD, FRCP, from the Departments of Anaesthetics and Medicine, Hammersmith Hospital and Royal Postgraduate Medical School, London WI2.

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FIGURE 1 Sheath drawn in two planes to illustrate the ventilation channels.

Sheath ' Ventilation tube ( l c n t e r n a l (6rnm internal diameter) / diameter)

/ Side holes (Ilrnmx 3mm)

* 421 cm

The telescope and lighting systems form a single unit when assembled within their carrier (figure 2). When this is orientated correctly and in- serted as far as possible into the outer sheath, an airtight fit is obtained at the instrument's proximal end. The provision of a side tube on the outer sheath enables the bronchoscope to be connected to an anaesthetic circuit by means of a 9.5mm flexo-metallic endotracheal tube (figure 3). The space between the sheath and telescope assembly is then available for ventilation (figures 2a and 4). A powerful light source is provided by a 100 watt, 12 volt tungsten lamp in a cooled housing near the eyepiece of the telescope (omitted, for clarity, from the drawings). The light from this source is re- flected and condensed into a quartz rod lying parallel to the telescope along its complete length (figures 2 and 4) and transmits brilliant illumin- ation to the field of vision. Adequate light for photography is made avail- able by temporarily overloading the lamp. Examples of photography taken through this system have already been published 1.

Sheath

auarlz rod

b r r w r

I

I Telescope

FIGURE 2 Drawings of components of the bronchoscope system.

rod and carrier assembled within the sheath, but partiah) withdrawn to show air passage between sheath

(a) Telescope, quartz

and carrier. (b) (b) Termination ofde-

misting tube at telescope objective lens.

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FIGURE 3 Photograph showing bronchoscope sheath in left main bronchus, the ventilation tube connected to the anaesthetic apparatus and the Emerson cuirass in place. (reprodcued by courtesy of E. & S. Livingstone Ltd, Edinburgh).

Because the telescope is in use almost constantly, a demisting facility must be incorporated as an integral part of the instrument. This is achieved by applying a very fine tube to the side of the telescope (figures 2b and 4) down which a gas can be passed to its tip: here the tube is bent or machined

FIGURE 4 Cross- section of sheath, with carrier in place, at level of ventilation tube to show dimensions of the components. The stippled area is the space available for ventilation.

Ve n t i la t ion

[for quartz]

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Anaesthesia yo1 24 no 3 JUI) 1969

appropriately to deflect the stream of gas across the objective lens. In practice 4 litres Ozlminute are introduced into the bronchial tree in this manner.

The telescope assembly is only removed for biopsy, suction procedures and the use of certain auxiliary telescopes. The biopsy forceps and tele- scopes are of small dimensions and carry their own fibre-optic lighting systems. During these manoeuvres, an airtight fit cannot be achieved at the proximal end of the bronchoscope.

METHOD

Thirty four unselected male patients requiring diagnostic bronchoscopy were studied. Their ages ranged from 38 years to 76 years (mean 60 years). Fifteen patients were placed in a cuirass ventilator* prior to induction and nineteen patients were ventilated by manual means only. Premedica- tion in all cases consisted of pethidine 50-100mg, promethazine 25-5Omg and atropine 0.6mg, one hour pre-operatively. Induction in all cases con- sisted of a sleep dose of sodium thiopentone followed by suxamethonium, 5 0 - l a g . The lungs were then ventilated with 100% 0 2 through a circle absorber by manual compression of the reservoir bag, with a mask applied to the face. The vocal cords were sprayed with 4ml of 4 % lignocaine hydro- chloride before insertion of the bronschoscope.

Group 1: manual ventilation After insertion of the bronchoscope into the trachea, the side tube was connected to the circle system of a Boyle’s machine. Gases were introduced initially at a flow rate of 15 litres per minute (5 litres 0 2 and 10 litres N20) and 0.5-1.0% halothane added. The fresh gas flow was altered as required. Ventilation was maintained by manual compression of the reservoir bag, the valve usually being tightly closed. Expired gases escaped mainly around the sides of the bronchoscope. On the occasions when the telescope was removed for cleaning of the distal end, thus leaving the prox- imal end of the bronchoscope open, the open end was occluded by the anaesthetist’s finger and ventilation continued down the full cross-sectional area of the instrument. During suction and biopsy procedures, the proximal end could not be closed off. At these times, the emergency oxygen by-pass was turned on and compression of the reservoir bag continued in the hope that there was sufficient gas flow to maintain some ventilation in spite of the leak.

Group 2: cuirass The bronchoscope was connected to the circle system of a Boyle’s

machine, the cuirass switched on and the negative pressure regulated by

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*J. H . Emerson & Co, 22 Cottage Park Avenue, Cambridge 40, Massachusetts, U.S.A.

Anaesthesia vol24 no 3 Jidy 1969

the anaesthetist (figure 3). Gases were introduced into the circle system at a rate of 15 litres per minute (5 litres 0 2 and 10 litres N20) with 0.5-1.0% halothane, the fresh gas flow subsequently being adjusted according to the degree of distension of the reservoir bag. The proximal end of the broncho- scope was occluded with a finger when the telescope was removed, ventil- ation being continued with the cuirass. During the operative procedures, the cuirass was left switched on, with the result that air was entrained through the proximal end of the bronchoscope together with the anaes- thetic gases.

In both groups, incremental doses of suxamethonium were given to maintain paralysis. Ventilation was always stopped when photographs were taken. At the end of the procedure, the bronchoscope was held in the trachea until respiratory efforts were judged adequate. It was then removed and oxygen was given via a face mask until the patient had fully recovered. All patients, except one, were awake within 3 4 minutes of the end of the procedure.

Experimental procedure Permission for arterial cannulation was obtained from each patient and a radial artery cannula was inserted under local analgesia, after checking for competence of the ulnar arterial circulation. This was performed in the anaesthetic room prior to induction in the theatre. A pre-operative control sample of arterial blood was obtained with the patient breathing air. The fist operative sample was taken when the bronchoscope was in the trachea and, where possible, further samples were taken at 5 minute intervals during the bronchoscopy.

Samples were analysed immediately for oxygen tension (Pa,), carbon dioxide tension (Pa,,) and pH using a Radiometer E5046 oxygen electrode* and a Radiometer capillary glass electrode standardized against the National Bureau of Standards buffers. The output from the oxygen and pH electrodes was read on a Radiometer pH 27 meter and the Pa,,, was determined by the interpolation method described by Andersen & Engel2. The duration of the bronchoscopy was noted.

RESULTS

The duration of bronchoscopy ranged from 5 to 30 minutes and averaged 15 minutes (figure 5). The results of the blood gas analyses for each group of patients are shown graphically in figures 6 and 7. The mean Pacos values for both groups up to 20 minutes are shown in figures 8 and 9. There was no significant difference between the two methods at any time. No statistical analysis was performed on the oxygen tensions, as the in- spired oxygen tensions were not measured and these were varied by the anaesthetist according to individual requirements. *V. & A. Howe, 48 Pembridge Road, London WII.

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Anaesthesia vol24 no 3 July 1969

9 0

80

7 0

6 0

5 0

40

Po CQ mmHq

3 0

2 0

-

-

-

-

-

-

-

-

14

PATIENTS

5 10 15 20 25 30 MINUTES

FIGURE 5 Duration of bronchoscopic examinations.

90 - 7

c?' 0 ; ;o IS ;o 2; io MINUTES MINUTES

FIGURE 6 Individual Paco, values of FIGURE 7 Individual Pace, values of the the 19 patients ventilated manually. 15 patients ventilated with the cuirass.

70 r 70 r

--?- MINUTES

I 20

FIGURE 8 Mean Paco, (values + I FIGURE 9 Mean Paco, values ( + I standard deviation) over a 20 minure standard deviation) over a 20 minute period for the 19 patients ventilated period for the 15 patients ventilated with manrially . the cuirass.

During bronchoscopy Pao, levels were maintained above 60mm Hg in both groups.

From the results, it can be seen that adequate ventilation could be main- tained by both methods for the duration of the operative procedure in the majority of patients. Three patients, however, deserve special comment.

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(1) A.H Group 2 (jigure 10). A 52 year old man in poor general con- dition, with a grossly distended abdomen due to ascites and hepatic metastases from a bronchial carcinoma. A right pleural effusion was also present. Adequate oxygenation was maintained, but the Paco, rose to a very high level (93mm Hg) and the pH fell to 7.15. Clinically, there were no untoward signs during the procedure (the anaesthetist did not know the results until afterwards), although it was noted that recovery of conscious- ness was slightly delayed.

(2) A . W Group I (figure 11). A 57 year old man with a recurrence of a right upper lobe carcinoma, previously treated with radiotherapy and inflammatory changes in the left lung. This patient was extremely difficult to ventilate and the bronchoscopist was requested to terminate the pro- cedure before the blood gas values were known.

( 3 ) G.R Group I (figure 12). A 70 year old man with left lower lobe collapse and obstructive airways disease (vital capacity 2.7 1, forced ex- piratory volume in 1 second I .3 1, FEVl/VC=46 %). Although oxygena- tion was not a problem, adequate ventilation could not be maintained in this patient.

193 B

Pa co2

Pa O2

mmHq - 7 5

40 -74

7 3

-

7 1

100 90 1

Pa O2 60

FIGURE 10 Blood gas and p H of patient A.H Group 2.

values

FIGURE 1 1 of patient A . W Group 1 .

Blood gas and p H values

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I ’ ’ I I 0 5 10 15 MINUTES

FIGURE 12 of pntienr G . R . Group 1.

Blood gas and pH values

D I S C U S S I O N

Several workers3949 5 have shown that a normal oxygen saturation and a normal or reduced Pa,,, can be obtained using a ventilation broncho- scope of the type described by Miindnich & Hoflehners. In addition, the incidence of cardiac arrhythmias is reduced when such an instrument is used7 and it would appear that anaesthesia for bronchoscopy with such a technique approaches the ideal. However, the bronchoscope used in this study cannot be classed as a true ventilation bronchoscope. This is due to the presence of the telescope, which severely restricts the area available for ventilation and results in a considerable resistance to inflation (table 1).

TABLE 1

Resistance of bronchoscope at varying gas flow rates LITRES/MINUTE I RESISTANCE TO FLOW

I (cm WATER)

10 1 2.2 I 1 5 3.9

6.0 12.4

20 30

19.5 30.4

40 50

I

It is generally accepted that the minimum Pa,, level to provide adequate tissue oxygenation is 60mm Hg (which approximates to an oxygen satur- ation (Sa,) of 90%). In 1958, Huckabees introduced the concept of excess lactate production as an indication of tissue hypoxia, but did not show any increase in this until the Pa,, had fallen to 2632mm Hg. Chamberlain & Lis9 state that hypoxia may result in excess lactate pro- duction and a rise in lactate/pyruvate ratio, but that the absence of such changes does not exclude the presence of tissue hypoxia. It is therefore probable that the tests available at present are not sensitive enough to detect minor or even moderate degrees of tissue hypoxia.

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Both anaesthetic techniques were associated, in a number of patients, with Pa,,. levels which were above the normal range and in three patients reached very high levels. Whether Pa,,, levels of this magnitude are harmful is debatable; certainly they are usual in apnoeic oxygenation techniques 10 which are widely practised. In our patients, however, the high Pa,,, levels tended to be associated with a fall in Pa,, sometimes towards a critical level on the oxygen dissociation curve. This situation is potentially dangerous to elderly patients with cardiac disease during anaesthesia for bronchoscopy. There is also a risk that high alveolar COz levels will exaggerate hypoxia should the patient be allowed to breathe air after anaesthesia, at a time when respiration may be depressed due to the effect of drugs.

The purpose of this study was not to elucidate the incidence of arrhyth- mias occurring with this technique. Therefore the ECG was only moni- tored in those patients with suspected cardiac ischaemia. No serious arrhythmias were noted in these patients. However the possibility of arrhythmias occurring must be considered in relation to the technique used. There are several reasons for the production of arrhythmias in these patients :

(1) Manipulation within the larynx, trachea and bronchial tree is well known to cause irregularities of heart action. These changes are probably reflex and mediated via the vagus and sympathetic systems. Complete vagal block would require about 3mg of atropine 1 1, a dose far in excess of that used clinically. However, partial vagal block with 0.6mg atropine would lead to an upset of the normal autonomic balance and to a prepon- derance of a sympathetic ‘tone’. This could well predispose to arrhyth- mias12 and, indeed, Johnstone & Nisbetl3 have shown that atropine can initiate arrhythmias of the sympathetic type.

(2) Whether C 0 2 levels alone of the magnitude found in our patients, can cause arrhythmias is doubtful. Frumin and his colleagues14 during experimental apnoeic oxygenation in man, in the absence of endobronchial manipulation, found arrhythmias in two out of eight patients, but these occurred at PacoB levels of 13Omm Hg and 250mm Hg respectively. They did stress that the level might be lowered in the presence of endobronchial manipulation. In hypercapnoeic man anaesthetized with nitrous oxide, Prys-Roberts &, Kelman15 failed to demonstrate any ECG abnormalities, the maximum Pa,,, level recorded being 94mm Hg.

(3) Ventricular arrhythmias are uncommon during uncomplicated halo- thane anaesthesia in man, in the presence of a normal PacOs16. Brady- cardia is common, although easily countered by atropine, but the combin- ation of halothane and a high Pacos level is well known to cause arrhyth- mias usually of sympathetic origin 1 79 1 *. Price and his co-workers 1 9 found that there was an arrhythmia-provoking threshold of Pa,,, under halothane anaesthesia, the mean level being 70mm Hg. However, Black

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et a/. 16 found the mean arrhythmia threshold of PacOI to be 92mm Hg. This value appeared to be unrelated to the halothane concentration used and was remarkably constant for one individual. (4) Another factor that must be borne in mind is the blood catecholamine

level. Millar20 has shown a rise in blood catecholamine levels in the hyper- capnoeic dog and this rise also occurs in the adrenalectomised animal21, thus indicating mobilization from extra-adrenal sources. Frumin and his colleagues 1 4 and Sechzer and his co-workers 2 2 have demonstrated a rise in plasma adrenaline and nor-adrenaline in man during respiratory acidosis. The combination of halothane and adrenaline is well known to cause arrhythmias 139 2 3224 and even cardiac arrest25326927. However, Price and his co-workers28 consider that the endogenous release of amines is more likely to cause arrhythmias than injected adrenaline.

Using a ventilation bronchoscope and an anaesthetic technique con- sisting of thiomebumal sodium, nitrous oxide, oxygen and intermittent suxamethonium, Koster 8c Nielsen7 found a 14% incidence of arrhyth- mias. Pa,,, levels were not measured in this series, but as previous workers 3.49 5 have shown that normal ventilation can be achieved by this method, in all probability the Pa,,, levels were not raised. Jenkins29 found the incidence of arrhythmias during the apnoeic oxygenation technique for bronchoscopy to be 44%. Although he did not measure the Pa,,, levels in these patients, it would be reasonable to assume, from his other worklo, that the levels were high. It would therefore appear that the com- bination of a high Paco, and bronchial manipulation leads to a high in- cidence of cardiac irregularities. Halothane was incorporated in the anaesthetic technique in our series. In some patients, Pacol levels were elevated and probably associated with a high level of endogenous catecho- lamines. The incidence of cardiac irregularities occurring as a result of the combination of these factors plus endobronchial manipulation is almost certainly high.

It is obviously desirable to prevent elevation of Pa,,, levels during this procedure. The telescope/lighting system of this bronchoscope is therefore being redesigned as a smaller unit which should allow better ventilation. As a further insurance against the development of arrhythmias, the use of halothane has now been abandoned in favour of ventilation with 100 % 0 2 and anaesthesia with a 0.1 % intravenous infusion of methohexitone. However, to maintain some perspective, it should be noted that some 900 bronchoscopies have been performed by the technique described without mortality.

It is probable that with the true ventilating bronchoscope, steadier levels of Pa,,* could be maintained with a cuirass ventilator than with manual ventilation. The cuirass will continue to ventilate despite opening of the anaesthetic circuit or a leak between the glottis and the broncho- scope sheath. There is still adequate ventilation even when the broncho-

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Anaesthesia vol24 no 3 July I969

scope is in the diseased lung for long periods. On the other hand, by paying meticulous attention to detail and taking every opportunity to ventilate when the telescope/lighting system is removed, the manual method has proved satisfactory with this bronchoscope in most cases.

In the two groups, both methods of ventilation failed badly on individual patients. Obesity, widespread lung disease, bronchospasm, pleural effusion, ascites, or enlargement of the liver and spleen might explain these failures. However, due to the combined high resistance of the broncho- scope and pulmonary pathology, the adequacy of either method of ventil- ation depended to a large extent on the experience of the anaesthetist with the particular method in use.

The limitations of the cuirass due to unsatisfactory fit or disease were defined by Safar30. This more cumbersome method has now been aban- doned for the simpler method of manual ventilation. The latter causes less pre-anaesthetic disturbance to the patients; it allows observation of chest movement (essential because of the impossibility of measuring ventilation consistently) and provides free access to the patient should an emergency situation arise e.g. cardiac arrest.

SUMMARY A N D CONCLUSIONS

The anaesthetic technique and bronchoscope used for bronchoscopic photography are described and the results of the blood gas analyses in 34 patients presented. Adequate ventilation for most patients can be provided by manual methods, without the need for special apparatus, provided scrupulous attention is paid to detail. It is concluded that ventilation with 100 % oxygen with methohexitone anaesthesia is probably safer than the use of halothane in situations where PacO, levels are likely to be raised, but that the maintenance of normal COz levels would provide for even greater safety.

Acknowledgements We would like to thank Miss S. Greenburgh and Miss B. Bird for technical assistance, Miss S. Jenkins for secretarial assistance, the Department of Medical Illustration at the Royal Postgraduate Medical School and Dr F. Trafficante for translating the article by Fava and his colleagues.

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