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Question 2 Should carbon dioxide detectors be used to check correct placement of endotracheal tubes in preterm and term neonates?
  1. Harsha Gowda
  1. Correspondence to Dr Harsha Gowda, Department of Paediatric Medicine, Leeds General Infirmary, Leeds LS1 3EX, UK; harsha9{at}hotmail.co.uk

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Scenario

The Pedi-Cap device (Covidien, Mansfield, Massachusetts, USA) is frequently used in neonatal resuscitation to check the position of the endotracheal (ET) tube in term and preterm neonates. As a paediatric trainee having worked in various regions of the UK you note a huge variability in this practice. Clinical assessment of chest expansion and air entry, with improvement in saturations, colour and heart rate have been used for decades and work well. Is the Pedi-Cap superior to clinical assessment for checking the position of the ET tube?

Structured clinical question

During intubation of neonates [patients], is a carbon dioxide detector [intervention] better than clinical assessment [comparison] to detect correct endotracheal tube placement [outcome]?

Search strategy and outcome

Medline (1948–April week 1, 2011) and Embase (1947–15 April 2011) using the Ovid interface and the Cochrane Library were searched using the search terms: Neonate/Newborn/Preterm/Infants/Babies AND Carbon dioxide detector/CO2 detector/Pedi-Cap/Capnography/End tidal CO2 AND Intubation/Endotracheal tube; limits: Humans.

The search of Medline yielded 41 articles and Embase yielded 43 articles (2 unique articles). No relevant reviews were found in the Cochrane Library.

Thirty-nine articles were excluded, leaving four well conducted prospective studies for review (table 2).

Table 2

Should carbon dioxide detectors be used to check correct placement of endotracheal tubes in preterm and term neonates?

There were no randomised controlled trials.

Commentary

Proper placement of the ET tube during resuscitation can be difficult, especially in neonates, and evidence suggests a significant rate of oesophageal intubation when neonatal tracheal intubation is attempted: the rates of successful intubation at the first attempt vary from 24% in junior trainees to 86% in consultants.1 Direct laryngoscopy and observation of the ET tube passing between the vocal cords is the standard criterion for verifying ET intubation.2 Detection of end-tidal carbon dioxide, however, serves as a valuable adjunct to confirm ET intubation, detect inadvertent oesophageal intubation and monitor for accidental tracheal extubation.

Many studies have shown the colorimetric ETCO2 (end-tidal carbon dioxide) detector to be sensitive and specific in confirming ET intubation in haemodynamically stable adults and children.3 However, there has always been a concern that carbon dioxide in a neonatal small tidal volume may be diluted in the large dead space of the early versions of these detectors, resulting in false negative results (ie, indicating oesophageal placement despite the correct intratracheal position of the ET tube). Therefore, a specific paediatric disposable colorimetric ETCO2 detector (Pedi-Cap) with an internal volume of 3 ml is used during neonatal intubation.4

In direct comparisons in adults, capnography was superior to clinical assessment but no single technique was perfect, and capnography was found to be less accurate in cardiac arrest.5 In paediatric patients weighing more than 2 kg and with spontaneous circulation, detection of exhaled carbon dioxide confirmed tracheal tube position in all cases, but during cardiac arrest the possibility of a false negative result required further confirmation of tracheal tube position.6

Four good quality neonatal studies4 7 10 11 found that capnography/Pedi-Cap identified tracheal tube position more rapidly than clinical assessment. In all studies direct visualisation of tracheal tube position (or clinical assessment) was used as the final ‘gold standard’. Hosono et al compared capnography with defined clinical assessments. Capnography was completely accurate in all babies studied, all of whom had spontaneous circulation and were less than 32 weeks gestation. This study also had a well defined method for defining tracheal tube position.7 All studies utilised a separate team to measure exhaled carbon dioxide, with the clinical team blinded to the measurements, and all four examined neonates with spontaneous circulation. Several cases of false negatives in neonates as well as false negatives occurring in adult and paediatric cardiac arrest have been reported.8 Therefore, capnography should be interpreted carefully in extremely small neonates or in those in whom extensive resuscitation is required.

All studies showed that detection of exhaled carbon dioxide confirms tracheal intubation in neonates with a cardiac output more rapidly and more accurately than clinical assessment alone. False negatives may occur in very low birthweight neonates and in those in cardiac arrest.8 False positives may occur in the presence of colorimetric devices contaminated with epinephrine (adrenaline), surfactant or atropine.9 There is no comparative information to recommend any one method for the detection of exhaled carbon dioxide in the neonatal population. It appears important to use ETCO2 detection during neonatal intubation.

Clinical bottom line

  • Detection of exhaled carbon dioxide confirms tracheal intubation in neonates with a cardiac output more rapidly and more accurately than clinical assessment alone. (Grade B)

  • False negatives may occur in neonates with cardiac arrest. (Grade C)

  • It is unclear if false positives occur with colorimetric devices contaminated with epinephrine, surfactant or atropine. (Grade D)

Acknowledgments

The author would like to thank Dr Bob Phillips for reviewing the manuscript and providing valuable suggestions.

References

View Abstract

Footnotes

  • Competing interests None.

  • Provenance and peer review Not commissioned; internally peer reviewed.

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