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NEW INSTRUMENT

Self-Inflating Parachute CuffA New Tracheostomy and Endotracheal Cuff

J. Abouav, MD, San Francisco, CaliforniaT. N. Finley, MD, San Francisco, California

There exists a direct relation between the pressureexerted on the tracheal mucosa by the cuffs of venti-lating tubes and the damage that ensues [1,2]. Fur-thermore, the extent and degree of damage are relat-ed to the period of cuff inflation required for ventila-tion: the longer the patient is kept on the respirator,the more severe the damage [3,4].

In recent years many attempts to minimize theofttimes life-threatening complications have been re-ported. Several have been directed at improving themethods and use of the ventilating tubes. Thesemethods have included meticulous attention to theminimal occluding pressure [5], periodic deflation ofcuffs [2], and the allowance of small leaks around thecuff [5,6]. Devices have been directed at achievingintermittent inflation of cuffs using additional equip-ment attached to the respirators [7-91 or improvingthe characteristics of the cuffs themselves, such aspre-stretching [IO] of the cuff and recently the use ofthe soft cuff as described by Grill0 et al [II]. Someinvestigators had previously designed other types ofsoft cuffs [12,13] and a few have attempted to designa self-inflating cuff of one characteristic or another[14--161. Most of the aforementioned methods havemet with little acceptance: the method is ineffective,the apparatus is cumbersome, or the performance ofthe cuff is unreliable.

From the Department of Surgery and the Pulmonary Laboratory, MountZion Hospital and Medical Center, San Francisco, California.Reprint requests should be addressed to Dr Abouav, Department ofSurgery, Mount Zion Hospita l and Medical Center, 1600 DivisaderoStreet, San Francisco, California 94115.

For the past two years we have been attempting todesign a cuff with the following desirable character-istics: 1) The lateral wall pressure exerted by thecuff on the tracheal mucosa should not exceed theairway pressure. 2) The lateral pressure should beintermittent, exerted only during the inflation peri-od. 3) The cuff should be reliable at all ventilatorypressures and flows and maintain this reliability forextended periods of time. 4) The cuff should not in-terfere with the normal movement of secretions inthe tracheobronchial tree. 5) The cuff should besimple and require minimal attention by the nursingstaff.

We believe the present device, the self-inflatingparachute cuff, satisfies these goals. The lateral

Figure 1. Parachute cuf f with open end facing distalend of endotracheal tube.Figure 2. The radial ly placed shr ouds which prevent eversion of he open ended c uf f .

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8/13/2019 The American Journal of Surgery Volume 125 Issue 5 1973 [Doi 10.1016%2F0002-9610%2873%2990159-1] J. Abo

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Abouav and Finley

Figure 3. A schemat ic diagram i l lustrat ing the inf lat ionand def lat ion of the parachute dur ing posi t ive pressureventi lation.wall pressure exerted by the cuff does not exceed air-way pressure. The cuff is intermittently inflated. It isreliable at all pressures and flows for at least manyweeks, does not cause pooling of secretions, requirespractically no attention by the nursing staff, andfunctions effectively for extended periods of time.

The self-inflating parachute cuff is made oflatex rubber. It is fashioned like a parachute withopen end toward the lung. Figure 1.) Its free edge isfixed to the distal end of the ventilating tube by aseries of radially placed shrouds which prevent itfrom becoming everted during its insertion and whensubjected to the back-pressure in the trachea duringthe inflation period of ventilation. Figure 2.) Thecuff effectively traps the back-flow during the infla-tion period and produces an effective seal against thetracheal mucosa. Figure 3A.) The cuff does not ef-fect a complete seal during expiration and thereforedoes not interfere with the movement of secretions.Figure 3B.)

This design of cuff has now been used by us in theexperimental laboratory of Mount Zion Hospital andMedical Center for over two years. It has worked ef-fectively with both pressure and volume cycled respi-rators, at ventilating pressure ranging from 10 to 60cm of water. It has been kept in the trachea of dogs

as long as six weeks without producing any damageto the mucosa.

This design of cuff is proposed as an effective solu-tion to some of the plaguing problems encountered inthe care of critically ill patients requiring continuousventilatory care.

SummaryA new self-inflating cuff for endotracheal or tra-

cheostomy tubes is described. It is self-inflating,never exerts a lateral wall pressure greater than tra-cheal pressure, is reliable at all ventilating pressuresand flows, and maintains its reliability for extendedperiods of time when tested in vivo.

References1. Cooper DJ, Grill0 HC: The evolution of tracheal injury due to

ventilating assistance through cuffed tubes. Ann Surg169: 334, 1969.2. Andrews MJ, Pearson FG: Incidence and pathogenesis of

tracheal injury following cuffed tube tracheostomy withassisted ventilation. Ann Surg 173: 249, 1971.

3. Lester RE, Trimble K: Reappraisal of tracheal injury fromcuffed tracheostomy tubes. Experiment in dogs. JAMA2-15: 625, 1971.4. Ching NP, Ayers SM, Paegle RP, Nealon TF Jr: The contri-bution of cuff volume and pressure in tracheostomy tubedamage. J Thorac Cardiovasc Surg 62: 402 1971.5. Hardy KL, Fettel BE, Shiley DP: New tracheostomy tube.Ann Thorac Surg 10: 58, 1970.

6. Gibson P: Aetiology and repair of tracheal stenosis followingtracheostomy and intermittent positive pressure respira-tion. Thorax 22: 1, 1967.

7. Crosby WM: Automatic intermittent inflation of tracheostomytube cuff. Lancet 2: 509 1964.8. Rainer WG, Sanchez M: Tracheal cuff inflation: synchronoustimed with inspiration. Ann Thorac Surg 9: 384 1970.9. Arens JF, Ochsner JL, Gee 0: Volume limited intermittentcuff inflation for long term respiratory assistance. J Tho-rat Cardiovasc Surg 58: 837 1969.10. Geffin B, Pontoppidan H: Reduction of tracheal damage byprestretching of inflatable cuffs. Anes 31: 462 1969.

11. Grill0 HC, Cooper JD, Geffin B, Pontoppidan H: A low pres-sure cuff for tracheostomy tubes to minimize trachealinjury. J Thorac Cardiovasc Surg 62: 898 1971.

12. Auchincloss JH Jr, Gilbert R, Mullison E: A new self inflat-ing tracheostomy cuff of silicon rubber for use in patientsrequiring mechanical aid to ventilation. Amer Rev RespDis 97: 706 1968.

13. Lomholt N: A new tracheostomy tube. Acta Anaesth Stand11: 311, 1967.14. Benveniste D: Endotracheal and tracheostomy tubes withself-inflating cuff. Acta Anaesth Stand 11: 85, 1967.15. Jackson RR, Rokowski WJ: A disposable endotracheal tubewith self inflating cuff. Arch Surg 94: 160, 1967.16. Martinez HE: An improved cuffed tracheostomy tube for usewith intermittent positive pressure breathing. J ThoracCardiovasc Surg 47: 404 1964.

658 The American Journal of Surgery