Endotracheal Tube Depth
We all know that airway management is a critical skill for those of us who care for pediatric patients in the acute environment! Due to conditions like severe respiratory illness (ex, asthma), acute trauma (ex, pulmonary contusion), or acute metabolic derangements (ex, DKA) children may benefit from endotracheal intubation. We must, however, remember, that in our efforts to help the child we must first do no harm, and the act of intubation has a large potential for inducing harm. One of the most important aspects of endotracheal intubation is proper positioning of the ETT. Let us take a moment to review Endotracheal Tube Depth.
Endotracheal Tube Depth: Do No Harm
- Unrecognized ETT misplacement (too high/too low) occurs frequently in Ped ED. [Miller, 2016]
- Low placement (i.e., mainstrem bronchus) is the most common misplacement!
- Younger patients and female patients are particularly at risk.
- Unrecognized ETT misplacement leads to complications!
- Inadequate / difficult ventilation
- Significant atelectasis
- Potential for unnecessary procedures (ex, misinterpretation of their being a pneumothorax leading to chest tube)
Endotracheal Tube Depth: Anticipate
- When planning to intubate, remind yourself of the proper positioning of the ETT
- Distal tip of the ETT should be between:
- The thoracic inlet and
- The carina.
- The ETT should be positioned and measured at the central incisor / alveolar ridge.
- Do not measure at the lip.
- Anticipate that this will be more challenging to achieve in children, particularly infants.
- Shorter tracheal length = less room for error
- The length from the vocal cords to the carina can vary between 5cm and 9 cm.
- Head / neck position plays a role!
- Neck extension will cause the ETT to move cephalad: potentially leading to extubation!
- Neck flexion will cause ETT to move toward carina: potentially going into mainstem bronchus!
Endotracheal Tube Depth: Estimate
- There are several formulas that can help estimate the depth in centimeters of the ETT.
- Personally, I am always a little leery any time there are multiple formulas to answer a question… (see Traumatic LP CSF Evaluation)
- Also, sadly, in the heat of the moment… doing complex calculus is not my strongest skill…
- Formulas can be useful to estimating initial tube placement, but their performance is variable for each individual patient.
- Age-based or height-based formulas are based on population statistics.
- Your individual patient may be outside the mean of that population!
- Most formulas are less accurate for children < 3 years of age. [Koshy, 2016]
- PALS Estimation
- For children > 1 year
- [Age (in years) / 2] + 12 (for oral ETT)
- Frequently leads to malpositioned ETT [Koshy, 2016; Lau, 2006]
- Internal Diameter Estimation
- 3 x ID of ETT
- Ex: 4.0 ETT => Depth = 12 cm
- Only used for ETT 3.0 or greater.
- Only predicted accurate placement in ~59% of cases. [Koshy, 2016]
Endotracheal Tube Depth: Auscultate?
- ETT placement confirmation has typically begun with auscultation of breath sounds.
- Equal / symmetric bilateral breath sounds would seem to suggest aeration from above the carina.
- The problem is that ETT’s with a Murphy eye can generate bilateral breath sounds even in the setting of a mainstem bronchial intubation.
- Bilateral breath sounds does not exclude mainstem intubation. [Verghese, 2004]
Endotracheal Tube Depth: Confirm!
- Chest Xray are traditionally used to confirm ETT position.
- Pros: CXR has been found to be superior to over formulas or other estimations. [Koshy, 2016]
- Cons: CXR is time consuming to obtain.
- Palpation of the trachea has been used to help determine ETT position. [Gamble, 2014]
- During intubation, another practitioner places 3 fingers on trachea with inferior finger at the sternal notch.
- The ETT is slowly advanced into the airway and positioned via external palpation.
- This was found to be superior to estimation formulas.
- Ultrasound can help you “see” the ETT position!
- An ultrasound probe positioned at the sternal notch can help locate the ETT. [Chowdhry, 2015; Chou, 2015; Tessaro, 2015]
- Much more readily available than CXR!
Moral of the Morsel:
- Your successful placement of the ETT through the cords is only the beginning of the airway management!
- Don’t celebrate too early! You have now placed the patient in a precarious position!
- Ensure that the ETT is appropriately positioned!
- Anticipate and Estimate, but Confirm!!!
- If there is any change in the child’s condition, Re-CONFIRM appropriate position of the ETT!
- Bring your Ultrasound to the bedside! Looking is better than listening!!
Miller KA1, Kimia A2, Monuteaux MC2, Nagler J2. Factors Associated with Misplaced Endotracheal Tubes During Intubation in Pediatric Patients. J Emerg Med. 2016 May 25. PMID: 27236246. [PubMed] [Read by QxMD]
Koshy T1, Misra S2, Chatterjee N2, Dharan BS3. Accuracy of a Chest X-Ray-Based Method for Predicting the Depth of Insertion of Endotracheal Tubes in Pediatric Patients Undergoing Cardiac Surgery. J Cardiothorac Vasc Anesth. 2016 Jan 29. PMID: 27238432. [PubMed] [Read by QxMD]
Pallin DJ1, Dwyer RC2, Walls RM3, Brown CA 3rd3; NEAR III Investigators. Techniques and Trends, Success Rates, and Adverse Events in Emergency Department Pediatric Intubations: A Report From the National Emergency Airway Registry. Ann Emerg Med. 2016 May;67(5):610-615. PMID: 26921968. [PubMed] [Read by QxMD]
Chowdhry R1, Dangman B2, Pinheiro JM1. The concordance of ultrasound technique versus X-ray to confirm endotracheal tube position in neonates. J Perinatol. 2015 Jul;35(7):481-4. PMID: 25611791. [PubMed] [Read by QxMD]
Tessaro MO1, Arroyo AC1, Haines LE1, Dickman E1. Inflating the endotracheal tube cuff with saline to confirm correct depth using bedside ultrasonography. CJEM. 2015 Jan;17(1):94-8. PMID: 25781388. [PubMed] [Read by QxMD]
Chou EH1, Dickman E2, Tsou PY3, Tessaro M2, Tsai YM4, Ma MH5, Lee CC6, Marshall J2. Ultrasonography for confirmation of endotracheal tube placement: a systematic review and meta-analysis. Resuscitation. 2015 May;90:97-103. PMID: 25711517. [PubMed] [Read by QxMD]
Gamble JJ1, McKay WP, Wang AF, Yip KA, O’Brien JM, Plewes CE. Three-finger tracheal palpation to guide endotracheal tube depth in children. Paediatr Anaesth. 2014 Oct;24(10):1050-5. PMID: 24958069. [PubMed] [Read by QxMD]
Kerrey BT1, Geis GL, Quinn AM, Hornung RW, Ruddy RM. A prospective comparison of diaphragmatic ultrasound and chest radiography to determine endotracheal tube position in a pediatric emergency department. Pediatrics. 2009 Jun;123(6):e1039-44. PMID: 19414520. [PubMed] [Read by QxMD]
Lau N1, Playfor SD, Rashid A, Dhanarass M. New formulae for predicting tracheal tube length. Paediatr Anaesth. 2006 Dec;16(12):1238-43. PMID: 17121553. [PubMed] [Read by QxMD]
Hsieh KS1, Lee CL, Lin CC, Huang TC, Weng KP, Lu WH. Secondary confirmation of endotracheal tube position by ultrasound image. Crit Care Med. 2004 Sep;32(9 Suppl):S374-7. PMID: 15508663. [PubMed] [Read by QxMD]
Verghese ST1, Hannallah RS, Slack MC, Cross RR, Patel KM. Auscultation of bilateral breath sounds does not rule out endobronchial intubation in children. Anesth Analg. 2004 Jul;99(1):56-8. PMID: 15281503. [PubMed] [Read by QxMD]
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