gauge that had earlier been used on this

patient. We were fortunate that inci-

dent happened in a stable patient

undergoing a routine procedure as the

consequences might, otherwise, have

been much worse.

B. M. Cornforth

Salisbury District Hospital

Salisbury SP2 8CJ, UK

E-mail: rrhh.bmc@btinternet.com

National survey of the routinemeasurement of tracheal tubecuff pressure in ICU

Over-inflation of a tracheal tube cuff

can lead to tracheal rupture, ischaemia

and necrosis of the tracheal mucosa,

tracheo-oesophageal fistulas, sore

throat, laryngeal stenosis and tracheo-

carotid artery erosion [1]. Under-infla-

tion can result in micro-aspiration [1]

and increase the risk of nosocomial

infections. Excessive cuff pressures

should be prevented by objective

measurement of the pressure [2]. In

the absence of clear guidelines, many

clinicians consider it reasonable to

maintain cuff pressures in the range of

20–30 cmH2O [1]. We undertook an

audit in our ICU which showed that

66% of cuff pressures measured were

found to lie in the recommended range

of 20–30 cmH2O. Twenty-two per-

cent were inflated to > 30 cmH2O, and

12% were inflated to < 20 cmH2O.

The highest recorded cuff pressure was

70 cmH2O.

Following this audit we conducted a

telephone survey of 79 ICUs across the

UK and asked the following questions:

‘are tracheal tube cuff pressures rou-

tinely measured in your unit’; if yes,

‘how often are measurements done’;

and ‘what is the target cuff pressure in

your unit’? We found that 68% of ICUs

routinely measure tracheal tube cuff

pressures. The frequency of measure-

ment varied from once per day to once

per shift. There was no uniformity in

the target cuff pressure. The target

pressure of some units was the ‘green

zone’, the value of which sometimes

varied with the brand of manometer

used, whereas the range in other units

varied from 14 to 35 cmH2O.

Viyas et al. surveyed 24 ICUs in the

Northern and Yorkshire regions in

2002 and found that 75% did not

routinely measure cuff pressures [3].

The Royal College of Anaesthetists

compendium of audit recipes suggests

that all cuffs should be correctly

inflated, that the correct cuff pressure

is that which is required to prevent a

leak, and that no cuff pressure should

exceed 35 cmH2O [4]. Our audit

revealed that this target is not yet

being met in our ICU and is not met

in at least 32% of ICUs nationally. We

therefore suggest that cuff pressures

should be measured routinely, the

recommendations of the Royal Col-

lege of Anaesthetists about cuff pres-

sures should be followed, and that

there should be a separate a cuff

pressure measuring device for each

critical care bed to avoid cross infec-

tion

N. Burke

R. Baba

A. Moghal

C. Hosahalli Vasappa

Mayday University Hospital

Croydon CR7 7YE, UK

E-mail: nburkits@yahoo.com

References1 Sengupta P, Sessler DI, Maglinger P,

et al. Endotracheal tube cuff pressure in

three hospitals, and the volume

required to produce an appropriate cuff

pressure. BMC Anesthesiology 2004; 4:

8.

2 Stewart SL, Secrest JA, Norwood BR,

Zachary R. A comparison of endotra-

cheal tube cuff pressures using estima-

tion techniques and direct intracuff

measurement. Journal of the American

Association of Nurse Anesthetists 2003; 71:

443–7.

3 Vyas D, Inweregbu K, Pittard A.

Measurement of tracheal tube cuff

pressure in critical care. Anaesthesia

2002; 57: 275–7.

4 Nightingale P, Griffiths H, Clayton J.

Tracheal tube cuff pressures. In: Raising

the Standard: a Compendium of Audit

Recipes for Continuous Quality Improve-

ment in Anaesthesia. London: Royal

College of Anaesthetists, 2006:

204–5.

Nerve stimulator-guidedcervical plexus block for carotidendarterectomy

Regional anaesthesia for carotid artery

surgery allows the patient to remain

awake so that the neurological status

can be assessed during cross-clamping.

However, this technique is unfamiliar

to many anaesthetists and, even in

experienced hands, failure may occur

[1, 2]. We describe a simple modified

technique based on a three-injec-

tion technique as described by Moore

[3].

The patient is placed in the semi-

sitting position with their head turned

slightly away from the side to be

blocked. The transverse processes of

C2, C3 and C4 are located approxi-

mately 1 cm posterior to the posterior

border of the sternomastoid muscle,

and intradermal infiltration of lidocaine

1% 0.25 ml for each level is performed.

The deep cervical plexus block is

performed using a short-bevelled nee-

dle (50 mm-Stimuplex; B Braun, Mel-

sungen, Germany) connected to a

nerve stimulator (Stimuplex DIG, B

Braun), and the needle inserted per-

pendicular to the skin, aiming in a

slightly caudal direction at the C2 level

to elicit neck muscle contractions. The

same technique is repeated at C3 and

C4. The tip of the needle is considered

to be correctly positioned when a

current intensity of 0.5 mA elicits a

neck muscle response. Five ml of local

anaesthetic mixture (bupivacaine 0.5%

and lidocaine 2%) is injected over 2–

3 min after a negative aspiration test.

The technique is completed by per-

forming a superficial cervical plexus

block by infiltration at the midpoint of

the sternomastoid muscle with 7 ml of

the same mixture and infiltration of 3–

5 ml of local anaesthetic mixture along

the inferior border of the mandible to

block the afferent branches from the

cranial nerves. This injection along the

mandible appears to reduce the pain

associated with prolonged use of a

retractor. We have found that patients

are rarely distressed or uncomfortable

during performance of these blocks.

We have obtained excellent results

Anaesthesia, 2007, 62, pages 289–300 Correspondence......................................................................................................................................................................................................................

� 2007 The Association of Anaesthetists of Great Britain and Ireland 299

with this technique in a number of

patients and further evaluation is

ongoing.

The use of a nerve stimulator for

deep cervical plexus blockade has been

previously reported for carotid surgery.

Mehta and Juneja [4] and Merle et al.

[5] used a single-injection technique,

guided by a nerve stimulator. In both

reports the technique was not com-

pletely successful and required supple-

mental intravenous analgesia or local

anaesthetic infiltration, particularly dur-

ing retractor placement and carotid

artery dissection. In our technique, the

identification of nerves of the cervical

plexus was more precise, requiring neck

muscle contraction prior to each of the

three injections.

Phrenic nerve palsy is frequent (up to

90%) after deep cervical plexus block.

The use of a nerve stimulator can elicit a

diaphragmatic muscle response which

helps to avoid the administration of the

local anaesthetic directly into the area of

the phrenic nerve. It has been reported

that the use of a nerve stimulator

decreases the peak serum concentration

(Cmax) and significantly slows the time

to reach peak concentration (Tmax) of

the local anaesthetic [5], both of which

are major determinants of systemic

toxicity.

A. Zeidan

F. Hayek

Sahel General Hospital

Beirut, Lebanon

E-mail: doczeidan@hotmail.com

References1 Lee KS, Davis CH, McWhorter JM.

Low morbidity and mortality of carotid

endarterectomy performed with re-

gional anesthesia. Journal of Neurosurgery

1988; 69: 483–7.

2 Murie JA, Morris PJ. Carotid endar-

terectomy in Great Britain and Ireland.

British Journal of Surgery 1986; 73: 867–

70.

3 Moore DC. Regional Block: a Hand-

book for the Use in the Clinical Practice

of Medecine and Surgery, 4th edn.

Springfield: Charles C Thomas, 1978:

21–4.

4 Mehta Y, Juneja R. Regional analgesia

for carotid artery endarterectomy by

Winnie’s single-injection technique

using a nerve detector. Journal of

Cardiothoracic and Vascular Anesthesia

1992; 6: 772–3.

5 Merle JC, Mazoit JX, Desgranges P,

et al. A comparison of two techniques

for cervical plexus blockade: evaluation

of efficacy and systemic toxicity.

Anesthesia and Analgesia 1999; 89:

1366–70.

Rebreathing due to incorrectlyfitted seal on an Aestiva S/5

An Aestiva S ⁄ 5 anaesthesia work station

(Datex Ohmeda, GE Healthcare, Hat-

field, UK) displayed a high carbon

dioxide reading (consistent with

rebreathing) during routine use. Fol-

lowing a detailed search the fault was

found. The seal on the carbon dioxide

bypass unit (whose function is to allow

removal and refilling of the soda lime

canister during use) was incorrectly

fitted inside out (Fig. 5), causing respir-

atory gases to bypass the soda lime

canister. We have been unable to

establish how this occurred. The

rebreathing resolved following correct

positioning of the seal. A correctly

placed seal fits flush with the metal

components of the bypass unit (Fig. 6).

When it is positioned ‘inside out’ the

soda lime canister still appears to fit.

However, significant rebreathing occurs

at low fresh gas flows.

J. Phillips

K. Jones

N. S. Parekh

New Cross Hospital

Wolverhampton WV10 0QP, UK

E-mail: Nilesh.Parekh@rwh-tr.nhs.uk

Figure 5 Seal incorrectly fitted (inside out).

Figure 6 Seal correctly fitted.

Correspondence Anaesthesia, 2007, 62, pages 289–300......................................................................................................................................................................................................................

300 � 2007 The Association of Anaesthetists of Great Britain and Ireland