Elsevier

Resuscitation

Volume 87, February 2015, Pages 1-6
Resuscitation

Clinical paper
Point of care ultrasound for orotracheal tube placement assessment in out-of hospital setting

https://doi.org/10.1016/j.resuscitation.2014.11.006Get rights and content

Abstract

Aim of the study

The percentage of unrecognised orotracheal tube displacement in an out-of-hospital setting has been reported to be between 4.8% and 25%. The aim of our study was to assess the sensitivity and specificity of Point-of-Care-UltraSound (POCUS) for confirming the proper tube position after an urgent orotracheal intubation in an out-of-hospital setting and the time needed for POCUS.

Methods

Our single-centred prospective study included all patients who needed out-of-hospital orotracheal intubation. After the intubation, bilateral chest auscultation and assessment of bilateral lung sliding and diaphragm excursion within POCUS were done. Spectrographic quantitative capnography was used as the reference standard to confirm a proper tube position.

Results

We enrolled 124 patients. For auscultation, sensitivity and negative predicted value were 100%, specificity was 90% and positive predicted value 30% (95% confidence interval). Sensitivity, specificity, positive predicted value, and negative predicted value for POCUS alone and for a combination of auscultation and POCUS were 100% (95% confidence interval). In three patients, we detected endobronchial tube displacement with auscultation and POCUS. Capnography failed to detect displacement in all three cases. The median time needed for POCUS was 30 s.

Conclusion

Results of our study support POCUS as an accurate and reliable method for confirming the proper orotracheal tube placement in trachea and it is feasible for out-of-hospital setting implementation. POCUS also seems to be time saving method but to make definitive conclusion more studies should be done.

Introduction

Maintaining of open airway and providing sufficient mechanical ventilation to a critically ill/injured patient or patient in cardiac arrest is one of the top priorities for an emergency physician. The golden standard for securing the airway is still orotracheal intubation.1, 2, 3 The difficulty of the procedure depends on the cause that requires intubation, the anatomy of the patient, the presence of oral cavity fluid/food, the obstruction of the airway and on the experiences of the physician.

Out-of-hospital setting itself makes the orotracheal intubation more difficult even for the most experienced anaesthesiologists,4 because of the weather conditions, noise, the lack of space, limited equipment and medication. Therefore options for the proper orotracheal tube placement are also limited. The most reliable method for confirming orotracheal tube placement in out-of-hospital setting is capnography performed with spectrographic quantitative capnography.1, 5 The specificity and sensitivity of the method is 100% but only if the capnograph waveform is interpreted by an experienced physcian.5 Additional limitation of the method is that it cannot distinguish between endotracheal placement and endobronchial misplacement or displacement of the tube.6

Multiple studies have shown that Poin-of-Care-UltraSound (POCUS) is very useful for the confirmation of the proper endotracheal tube position in non-emergency and emergency situations. To our knowledge only one case has been reported regarding endotracheal tube position assessment with POCUS in a pre-hospital setting. Other studies include cadaveric cases, patient undergoing elective operations in operating theatres or critically ill/injured patients urgently intubated in emergency departments.6, 7, 8, 9, 10, 11, 12, 13, 14, 15

Also Zechner and Breitkreutz in their ultrasound (US)-based airway management comment conclude: “a real-time based RSI and upper airway ultrasound procedure may enhance physician confidence and decision-making in relation to tracheal tube placement and may have its place in combination with continuous capnography in emergency patients.”16 To expand the possibilities for confirming the proper orotracheal tube position in an out-of-hospital setting and maybe even to find a better method than capnography, we investigated the usage of POCUS for the endotracheal tube position conformation after an urgent orotracheal intubation in an out-of-hospital setting. Unrecognised tube misplacement or displacement can be devastating for the patient. The percentage of an unrecognised tube displacement in an out-of-hospital setting is reported to be between 4.8% and 25%.17, 18 To improve the recognition of non-proper tube placement POCUS could be useful in an out-of-hospital setting. The main goal of our study was to estimate the diagnostic accuracy of POCUS – a combination of lung sliding and diaphragm excursion assessment for confirming the proper orotracheal tube position in patients after an urgent orotracheal intubation by an emergency physician in out-of-hospital setting.

Section snippets

Study design and setting

The National Medical Ethics Committee of Slovenia approved the study. Our single-centred prospective study was conducted between January 2011 and January 2014. All patients were orotracheally intubated by emergency physician in the field that is covered by the Prehospital Unit Maribor.

Selection of participants

All orotracheal intubated patients regardless to the indication for orotracheal intubation were prospectively enrolled when investigators or study associates and portable US machine in an out-of-hospital setting

Results

We enrolled 124 patients who needed orotracheal intubation (Fig. 1). The main characteristics of study subjects are listed in Table 1.

The sensitivity, specificity, PPV and NPV of chest auscultation, POCUS and the combination of both (chest auscultation and POCUS) for airway intubation versus oesophageal are listed in Table 2. In Table 3 we report a cross tabulation of the capnography as the reference standard and index tests.

In our study 89.5% (111 patients) of patients were orotracheally

Discussion

Our study aimed to assess the usefulness of POCUS for confirming the proper orotracheal tube position in patients after urgent orotracheal intubation performed by emergency physician in an out-of-hospital setting. Within POCUS the assessment of the lung sliding and the diaphragm excursion was performed.

In 10.5% (13 patients) of patients the tube was placed in the oesophagus requiring a second attempt of orotracheal intubation. Among 13 intubations in oesophagus only 30% of the cases (four

Conclusions

The results of our prospective study support lung sliding and diaphragm assessment within POCUS to be accurate, reliable and feasible method for assessing of the orotracheal tube position after urgent intubation. With POCUS orotracheal tube misplacement can be detected earlier, which is life-saving. The combination of lung sliding assessment and diaphragm assessment is feasible for out-of-hospital setting implementation also in countries with a lack of experienced physicians in the

Conflict of interest statement

The authors have no conflict of interest to declare.

Acknowledgement

We would like to thank Miro Palfy for suggestions for statistical analysis and assistance with statistical computing.

References (24)

Cited by (26)

  • European Resuscitation Council Guidelines for Resuscitation 2015. Section 3. Adult advanced life support.

    2015, Resuscitation
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    The role of thoracic impedance as a tool to detect tracheal tube position and adequate ventilation during CPR is undergoing further research but is not yet ready for routine clinical use. Three observational studies including 254 patients in cardiac arrest have documented the use of ultrasound to detect tracheal tube placement.621–623 The pooled specificity was 90% (95% CI 68–98%), the sensitivity was 100% (95% CI 98–100%), and the FPR was 0.8% (95% CI 0.2–2.6%).

  • Part 4: Advanced life support. 2015 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science with Treatment Recommendations

    2015, Resuscitation
    Citation Excerpt :

    Low-quality evidence (downgraded for risk of bias and suspected publication bias) from 1 observational study41 showed no statistically significant difference between the performance of a bulb (sensitivity 71%, specificity 100%)- and a syringe (sensitivity 73%, specificity 100%)-type esophageal detection devices in the detection of tracheal placement of a tracheal tube. For the important outcome of detection of correct placement of a tracheal tube during CPR, we identified low-quality evidence (downgraded for suspicion of publication bias and indirectness) from 3 observational studies51–53 including 254 patients in cardiac arrest that evaluated the use of ultrasound to detect tracheal tube placement. The pooled specificity was 90% (95% CI, 68–98%), the sensitivity was 100% (95% CI, 98–100%), and the FPR was 0.8% (95% CI, 0.2–2.6%).

  • Prehospital Ultrasound: A Narrative Review

    2024, Prehospital Emergency Care
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A Spanish translated version of the abstract of this article appears as Appendix in the final online version at http://dx.doi.org/10.1016/j.resuscitation.2014.11.006.

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