Consequences of cuff pressure

I was interested to read the case report (Stewart & Lindsay.  Anaesthesia 2002; 57: 264-5).  This report highlights the importance of paying attention to the intracuff pressure of the airway to avoid pressure-related complications including neurovascular injuries.  A few products have been marketed recently for use to maintain airway patency during anaesthesia (1-3).  All of these products have a large oropharynheal cuff, which is designed to be inflated with large volume of air to provide airtight seal.  Studies using these devices have recorded a very high intracuff pressure (1, 2).  In their study, Enlund and colleagues recorded a pressure of 110cm of water, even after under-inflation with half of the recommended volume of air (4).  This study indicates that there may not be a liner relationship between the cuff volume and the intracuff pressure when the device is inserted into the airway.  It will depend on the compliance of the oropharynx too, which will vary from patient to patient.  Thus, the best way to minmise the pressure-related complications is to record intracuff pressure and adjust it accordingly by changing the cuff volume.  Although the authors (1) have advocated a cuff pressure below 20 cm of water, others have recommended a pressure of 60 cm to be safe (2).  Hence, there is disagreement on this issue and further investigation is needed to define the safe level of pressure.

In the presence of an unobstructed airway, it is difficult to detect any malposition of the tube in routine clinical practice.  Thus, paying attention to the intracuff pressure could avoid many complications.  Finally, hypotension associated with high intracuff pressure could contribute to such complications.  We should recognise this problem and steps should be taken to avoid it.

N.G Mandal.  Peterborough District Hospital, Peterborough PE3 6DA, UK

Reference
1 Asai T, Murao K, Shingu K.  Efficacy of the laryngeal tube during intermittent positive pressure ventilation.  Anaesthesia 2000; 55: 1099-102. 
2 Gaitini LA, Vaida SJ, Mostafa S, et al.  The combitube in elective surgery: a report of 200 cases.  Anesthesiolgy 2001; 94: 79-82.
3 Mandal NG, Hebblethwaite R.  Experience with the Airway Management Device.  An audit of 50 consecutive cases.  Today’s Anaesthetist 2001; 16: 67-8. 

The effect of laryngeal mask cuff pressure on postoperative sore throat incidence

Conclusions: A significant increase in cuff pressure is seen during the first 60 minutes.

Laryngeal mask airway and tracheal tube cuff pressures in children: are clinical endpoints valuable for guiding inflation?

Summary
The use of clinical endpoints alone was associated with significant hyperinflation of cuffs with both devices in almost all patients, with an exacerbation when nitrous oxide was used.  In order to avoid unnecessary cuff hyperinflation in laryngeal mask airways and tracheal tubes, the routine use of cuff manometers is mandatory in children. 

Reference
Dr von Ungern-Stemberg, Anesthesia, 2008

The effect of nitrous oxide on the cuff pressure of the laryngeal tube

Case Report
Bilateral hypoglossal nerve injury following the use of the laryngeal mask airway

A healthy 54 year old man undergoing elective knee arthroscopy developed bilateral hypoglossal nerve palsy, lasting 6 weeks following the use of a laryngeal mask airway.  He suffered impairment of speech and difficulty in swallowing, the latter resulting in almost 7 kg loss of weight within 2 weeks of surgery.  We discuss the possible aetiology of the injury and review the literature describing injuries to the hypoglossal nerve. 

Reference
Dr A. Stewart and Dr W.A. Lindsay.  Anesthesia, 2002

Tracheal tube cuff pressures

Vyas and his colleagues described a range of tracheal tube cuff pressures from 12 to 100 cmH2o but it was not apparent whether the cuffs were initially inflated according to a local regimen or to 18-24 cmH2o using the Control-Inflater device (Vyas et al. Anaesthesia 2002; 57: 275-7).  We measured tracheal tube and tracheotomy cuff pressures continuously, having inflated the cuffs to the minimum occluding pressures determined by the absence of breath sounds over the neck and at the mouth on auscultation.  High residual volume, low pressure cuffs were found to have baseline pressures ranging from 18 to 61 cmH2o (mean 33 cmH2o).  These values decreased with time, probably as a result of slow movement of the plastic cuff material (creeping) and diffusion of gases.  Large increases in cuff pressures were recorded when the patient coughed with peak pressures as high as 210 cmH2o (1). 

R. Greenbaum.  The Middlesex Hospital, London W1N 8AA, UK Anesthesia, 2002

Reference
1 Jacobson L, Greenbaum R. A study of intracuff pressure measurements, trends and behaviour in patients during prolonged periods of tracheal intubation.    British Journal of Anesthesia 1981; 53:97-101.

Nerve injury and the laryngeal mask airway

The laryngeal mask airway is a widely used, non-invasive, general purpose airway.  We report the case of a temporary vocal cord palsy following the use of such an airway.  The development of inappropriately high cuff pressures secondary to nitrous oxide diffusion into the cuff is proposed as the most likely cause.  Knowledge of the existence of nerve injuries complicating laryngeal mask use is particularly important when counsellling certain patients.  Mandatory intraoperative cuff pressure monitoring should lower the risk of subsequent voice problems.

When nitrous oxide is used it is always recommended that the cuff pressure should be periodically checked and intermittently withdrawn to maintain “just seal pressure”. It has been shown that the pressure exerted by the cuff is not evenly distributed.

I.A. Bruce M.R.C.S, R. Ellis F.R.C.A and N.J. Kay F.R.C.S.  Department of Otolaryngology, Stepping Hill Hospital, Stockport, UK and Department of Anaesthesia, Stepping Hill Hospital, Stockport, UK

Reference
The Journal of Laryngology & Otology (2004) 118: 899-901 Cambridge University Press

Intracuff Pressure monitoring during Nitrous Oxide Anesthesia when using the Soft Seal R Laryngeal Mask

These results suggest that Soft SealR LM provided a reduction in nitrous oxide diffusion into the cuff; however, cuff deflation was needed to keep intracuff pressure at 60 cm H2o.  We therefore still recommend the careful monitoring of the intracuff pressure during nitrous oxide anesthesia, even when using the Soft SealR LM.

Masahiro Kanazawa, M.D., Toshiyasu Suzuki, M.D.  Tokai University School of Medicine, Kanagawa, Japan.

Reference
1 van Zundert AA, Fonck K, Al-Shaikh B, Mortier E: Comparison of the LMA-ClassicTM with the new disposable Soft SealR   Laryngeal Mask in spontaneously breathing adult patients.  Anesthesiology 2003; 99:1006-71.  Published 2004.

Effect of cuff pressure on changes in airway morphology after use of the laryngeal mask airway

Why should I try to achieve an intracuff pressure of 60 cm H2o and how do I measure this? 

There is evidence that low intracuff pressures/volumes are beneficial to patients.  Low intracuff pressures (less than 60 cm H2o) have been reported to reduce the incidence of sore throat and provide better airway sealing pressures than at high cuff pressures.  In addition, low cuff volumes have also been reported to provide a better seal and fiberoptic positioning than at high cuff volumes. 

Reference
Journal of Anesthesia 2003; 17:133-135.