Department of Anaesthesia, University Children's Hospital Zurich, Steinwiesstrasse 75, CH-8032 Zurich, Switzerland
* Corresponding author. E-mail: markus.weiss{at}kispi.unizh.ch
Accepted for publication June 26, 2004.
![]() |
Abstract |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Methods. With local Institutional Ethics Committee approval and informed parental consent, we included patients from birth (weighing 3 kg) to 16 yr who were undergoing general anaesthesia requiring orotracheal intubation. Tracheal intubation was performed using direct laryngoscopy, the intubation depth mark was placed between the vocal cords, and the tube was taped to the lateral corner of the mouth. The distance between the tube tip and the tracheal carina was assessed by flexible bronchoscopy with the patients in supine, and their head in neutral positions. Tube sizes were selected according to the formula: internal diameter (ID; mm)=(age/4)+3.5 in children
2 yr. In full-term newborns (
3 kg) to less than 1 yr ID 3.0 mm tubes were used and in children from 1 to less than 2 yr ID 3.5 mm tubes were used. Endoscopic examination was performed in 50 size ID 3.0 mm tubes, and in 25 tubes of each tube size from ID 3.5 to 7.0 mm. Tracheal length and percentage of the trachea to which the tube tip was advanced were calculated.
Results. 250 patients were studied (105 girls, 145 boys). The distance from the tube tip to the carina ranged from 1.4 cm in a 2-month-old infant (ID 3.0 mm) to 7.7 cm in a 14-yr-old boy (ID 7.0 mm). Mean tube insertion into the trachea was 53.2% (6.3) of tracheal length with a minimum of 40% and a maximum of 67.6%.
Conclusions. The insertion depth marks of the new Microcuff paediatric tracheal tube allow adequate placing of the tracheal tube with a cuff-free subglottic zone and without the risk for endobronchial intubation in children from birth to adolescence.
Keywords: children ; equipment, cuffs tracheal ; intubation, tracheal ; monitoring, depth mark
![]() |
Introduction |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
However, as reviewed recently by Goel and Lim, a large disparity exists in the position and the presence of depth marks, bands, and lines between different types of uncuffed and cuffed tracheal tubes.3 Similarly, the lack of intubation depth marks and inappropriately high positioned depth marks in cuffed paediatric tubes have been reported.36 In the latter, the tube tip will become positioned critically deep in the trachea, when placed according to the depth marks. Further, even with the upper cuff border positioned directly below the vocal cords, a small margin of safety regarding endobronchial intubation has been reported in cuffed paediatric tubes because of long tube cuffs and Murphy eyes.7 If placed with the tip in the mid-tracheal position, in many tracheal tubes the cuff will lie within the larynx, again particularly in those with long cuffs and a Murphy eye.4
Recently, a new cuffed paediatric tracheal tube (Microcuff Paediatric Tracheal Tube, Microcuff GmbH, Weinheim, Germany) with a high volume-low pressure cuff has been introduced. The thin-walled cuff is made from polyurethane, which is thought to improve sealing characteristics, allowing shorter cuffs.8 The short cuff and the avoidance of a Murphy eye allows appropriate intubation depth with a cuff-free subglottic tube shaft.
The aim of the present study was to evaluate the appropriateness of the intubation depth marks in the new Microcuff paediatric tracheal tube in a large population of patients ranging from neonates to adolescence.
![]() |
Methods |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
|
|
|
Statistical analysis
Data are presented as mean (SD) and/or median and range as appropriate. Tracheal length (vocal cords to carina distance) was calculated by adding the distance from depth mark to tube tip to the measured distance from tube tip to carina. The percentage of the trachea to which the tracheal tube tip was advanced within the trachea was calculated. Linear and/or logarithmic regression models were calculated for the relationship of the distance from the tube tip to the carina, calculated tracheal length and tube insertion depth to age, weight, and length. In patients 2 yr of age, the distances from the tube tip to carina were compared with those derived from standard formulae for oral tube insertion (insertion depth [cm]=11.5+[age(yr)x0.5] and 12+[age(yr)x0.5], respectively).19 95% confidence intervals (CI) were calculated for tracheal length and compared with those reported from radiological examination.1 9
![]() |
Results |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
|
|
|
|
Calculated 95% CIs for measured trachea length, and those reported from radiological examination1 9 are presented in Table 4. Our data are comparable with those reported by Griscom.1
|
![]() |
Discussion |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Intubation depth marks in paediatric tracheal tubes were introduced for safe positioning of tracheal tubes, particularly in the emergency situation when tracheal intubation often has to be performed by inexperienced personnel. Correctly positioned intubation depth marks on tubes should allow a cuff-free subglottic tube shaft,47 21 appropriate tracheal tube insertion depth to avoid endobronchial intubation,22 and inadvertent extubation during manipulation of the head.1013 Unfortunately, there are no British, European, or American standards for tracheal tube markings23 24 and each manufacturer has its own intubation depth marks.3 4 25 Based on our measurements, the intubation depth marks of the Microcuff paediatric cuff tracheal tube guarantee a cuff-free subglottic area, allow adequate placing of the tracheal tube and minimize the risk of endobronchial intubation or accidental extubation, even with caudal and cranial tube tip displacement because of headneck flexion and extension (Fig. 3).1013
The age-related formula for oral tube insertion depth in children 2 yr of age calculated on the basis of our data resulted in an overall tube insertion depth of 0.5 cm less than the conventionally used formula for children aged more than 2 yr (insertion depth [mm])=12+(age [yr]x0.5).14 19 The main reason for this is, that the intubation depth marks of the Microcuff tracheal tube were placed so that the tube tip becomes situated at 6065% of the shortest trachea of the intended age group while still leaving a safe margin for caudal tube displacement with head flexion (Table 1). Consequently, in a larger patient receiving a similar sized tube, the tube would be advanced to a shorter percentage of the trachea, resulting in a reduced oral insertion depth (compared with standard formulae) and an increased distance from tube tip to carina. This is not a shortcoming of the intubation depth marks, but reflects a consistent problem with paediatric tracheal tubes, that outer diameter, preformed bend, and depth marks will not be appropriate for each individual in an age range of 2 yr. Multiple intubation depth marks could be used to indicate age-dependent insertion depth. However, multiple markings on the distal end of a tube could be confusing during intubation. Nevertheless, the proposed intubation depth marks allowed safe placement of the cuffed tracheal tube in all children in our study (Fig. 3).
Several techniques, other than depth marks, have been proposed for determining the appropriate tube insertion depth: palpation of the tube tip or the cuff in the jugular fossa,26 27 endobronchial intubation followed by tube draw-back until bilateral breath sounds are heard or inspiratory pressure decreases,28 endoscopic control29 or lighted stylet,30 chest X-ray, and formula-based insertion depth.14 19 These techniques may be appropriate for uncuffed tubes; however, in many conventional cuffed tubes, the subglottic and the intra-glottic position of the tube cuff still can occur.37 Thus, cuffed paediatric tubes should be initially inserted according to an appropriately placed intubation depth mark to guarantee a cuff-free subglottic airway.
In conclusion, intubation depth marks are useful in cuffed paediatric tubes to guarantee adequate tracheal tube placement with a cuff-free subglottic airway and a sufficient margin for preventing inadvertent endobronchial intubation, or tracheal extubation. Based on our findings, the intubation depth marks of the Microcuff paediatric tracheal tube allowed the safe placement of a cuffed tracheal tube in children from a wide age range and were an improvement on the age-based formulae for oral tube insertion depth.
![]() |
Footnotes |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
![]() |
References |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
2 Loew A, Thibeault D. A new and safe method to control the depth of endotracheal intubation in neonates. J Pediat 1974; 54: 5068
3 Goel S, Lim SL. The intubation depth marker: the confusion of the black line. Paediatr Anaesth 2003; 13: 57983[CrossRef][ISI][Medline]
4 Weiss M, Dullenkopf A, Gysin C, Dillier C, Gerber AC. Shortcomings of paediatric cuffed endotracheal tubes. Br J Anaesth 2004; 92: 7888
5 Holzki J. Tuben mit cuff im neugeborenen- und kleinkindesalter ein risiko!. Anaesthesist 2002; 51: 3213[CrossRef][ISI][Medline]
6 Dillier CM, Trachsel D, Baulig W, Gysin C, Gerber AC, Weiss M. Laryngeal web due to an inappropriately designed cuffed paediatric endotracheal tube. Can J Anaesth 2004; 51: 725
7 Ho AMH, Aun CST, Karmakar MK. The margin of safety associated with the use of cuffed paediatric tracheal tubes. Anaesthesia 2002; 57: 16982[ISI][Medline]
8 Dullenkopf A, Schmitz M, Gerber AC, Weiss M. Sealing characteristics of pediatric cuffed tracheal tubes. Pediatr Anesth 2004; 14: 82530[CrossRef][ISI]
9 Pettersson H, Ringertz H. Measurements in Pediatric Radiology. London: Springer, 1991
10 Todres ID, deBros F, Kramer SS, Moylan FMB, Shannon DC. Endotracheal tube displacement in the newborn. J Pediatr 1976; 89: 1267[ISI][Medline]
11 Donn SM, Kuhns LR. Mechanism of endotracheal tube movement with change of head position in the neonate. Pediatr Radiol 1980; 9: 3740[ISI][Medline]
12 Sugiyama K, Yokoyama K. Displacement of the endotracheal tube caused by change of head position in pediatric anesthesia. Evaluation of fiberoptic bronchoscopy. Anesth Analg 1996; 82: 2513[Abstract]
13 Conrady PA, Goodman LR, Lainge F, Singer MM. Alteration of endotracheal tube position. Crit Care Med 1976; 4: 812[ISI]
14 Motoyama EK. Endotracheal intubation. In: Motoyama EK, Davis PJ, eds. Smith's Anesthesia for Infants and Children, 5th Edn. St Louis: CV Mosby Co., 1990; 2725
15 Steward DJ, Lerman J. Techniques and procedures of pediatric anesthesia. In: Steward DJ, Lerman J, eds. Manual of Pediatric Anesthesia, 5th Edn. New York: Churchill Livingstone, 2001; 69127
16 Khine HH, Corddry DH, Kettrick RG, et al. Comparison of cuffed and uncuffed endotracheal tubes in young children during general anesthesia. Anesthesiology 1997; 86: 62731[CrossRef][ISI][Medline]
17 Schild JA. Relationship of laryngeal dimensions to body size and gestational age in premature neonates and small infants. Laryngoscope 1984; 94: 128492[ISI][Medline]
18 Kahance JC. Growth of the human prepubertal and pubertal larynx. J Speech Hear Res 1982; 25: 44655[ISI][Medline]
19 Hatch DJ. Paediatric anaesthetic equipment. Br J Anaesth 1985; 57: 67284[Abstract]
20 Prader A, Largo RH, Molinari L, Issler C. Physical growth of Swiss children from birth to 20 years of age. Helv Paediat Acta 1989; (Suppl.) 52
21 Cavo JW. True vocal cord paralysis following intubation. Laryngoscope 1985; 95: 13529[ISI][Medline]
22 Kuhns LR, Poznanski AK. Endotracheal tube position in the infant. J Pediat 1971; 78: 9916[ISI][Medline]
23 British Standard. British Standard BS EN 1782. 1998; ISBN 0 580 29716 0:8
24 American Society for Testing and Materials. Standard specifications for cuffed and uncuffed tracheal tubes (ASTM F124289). Philadelphia: ASTM, 1989
25 Wallace CJ, Bell Graham TB. Tracheal tube markings. Pediatr Anesth 2004; 14: 2835[ISI]
26 Bednarek FJ, Kuhns LR. Endotracheal tube placement in infants determined by suprasternal palpation: a new technique. Pediatrics 1975; 56: 2249[Abstract]
27 Pollard RJ, Lobato EB. Endotracheal tube location verified reliably by cuff palpation. Anesth Analg 1995; 81: 1358[Abstract]
28 Bloch EC, Ossey K, Ginsberg B. Tracheal intubation in children: a new method for assuring correct depth of tube placement. Anesth Analg 1988; 67: 5902[ISI][Medline]
29 Heller RM, Cotton RB. Early experience with illuminated endotracheal tubes in premature and term infants. Pediatrics 1985; 75: 6646[Abstract]
30 Dietrich KA, Strauss RH, Cabalka AK, Zimmerman JJ, Scanlan KA. Use of flexible fiberoptic endoscopy for determination of endotracheal tube position in the pediatric patient. Crit Care Med 1988; 16: 8847[ISI][Medline]