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Endobronchial intubation detected by insertion depth of endotracheal tube, bilateral auscultation, or observation of chest movements: randomised trial

BMJ 2010; 341 doi: (Published 09 November 2010) Cite this as: BMJ 2010;341:c5943
  1. Christian Sitzwohl, assistant professor 1,
  2. Angelika Langheinrich, resident1,
  3. Andreas Schober, resident1,
  4. Peter Krafft, associate professor2,
  5. Daniel I Sessler, professor and chair3,
  6. Harald Herkner, associate professor4,
  7. Christopher Gonano, associate professor1,
  8. Christian Weinstabl, associate professor2,
  9. Stephan C Kettner, associate professor2
  1. 1Department of Anaesthesiology, General Intensive Care, and Pain Control, Medical University of Vienna General Hospital, A-1090 Vienna, Austria
  2. 2Department of Anaesthesiology, General Intensive Care, and Pain Control, Medical University of Vienna General Hospital
  3. 3Department of Outcomes Research, Cleveland Clinic, Ohio, USA
  4. 4Department of Emergency Medicine, Medical University of Vienna General Hospital
  1. Correspondence to: C Sitzwohl christian.sitzwohl{at}
  • Accepted 7 September 2010


Objective To determine which bedside method of detecting inadvertent endobronchial intubation in adults has the highest sensitivity and specificity.

Design Prospective randomised blinded study.

Setting Department of anaesthesia in tertiary academic hospital.

Participants 160 consecutive patients (American Society of Anesthesiologists category I or II) aged 19-75 scheduled for elective gynaecological or urological surgery.

Interventions Patients were randomly assigned to eight study groups. In four groups, an endotracheal tube was fibreoptically positioned 2.5-4.0 cm above the carina, whereas in the other four groups the tube was positioned in the right mainstem bronchus. The four groups differed in the bedside test used to verify the position of the endotracheal tube. To determine whether the tube was properly positioned in the trachea, in each patient first year residents and experienced anaesthetists were randomly assigned to independently perform bilateral auscultation of the chest (auscultation); observation and palpation of symmetrical chest movements (observation); estimation of the position of the tube by the insertion depth (tube depth); or a combination of all three (all three).

Main outcome measures Correct and incorrect judgments of endotracheal tube position.

Results 160 patients underwent 320 observations by experienced and inexperienced anaesthetists. First year residents missed endobronchial intubation by auscultation in 55% of cases and performed significantly worse than experienced anaesthetists with this bedside test (odds ratio 10.0, 95% confidence interval 1.4 to 434). With a sensitivity of 88% (95% confidence interval 75% to 100%) and 100%, respectively, tube depth and the three tests combined were significantly more sensitive for detecting endobronchial intubation than auscultation (65%, 49% to 81%) or observation(43%, 25% to 60%) (P<0.001). The four tested methods had the same specificity for ruling out endobronchial intubation (that is, confirming correct tracheal intubation). The average correct tube insertion depth was 21 cm in women and 23 cm in men. By inserting the tube to these distances, however, the distal tip of the tube was less than 2.5 cm away from the carina (the recommended safety distance, to prevent inadvertent endobronchial intubation with changes in the position of the head in intubated patients) in 20% (24/118) of women and 18% (7/42) of men. Therefore optimal tube insertion depth was considered to be 20 cm in women and 22 cm in men.

Conclusion Less experienced clinicians should rely more on tube insertion depth than on auscultation to detect inadvertent endobronchial intubation. But even experienced physicians will benefit from inserting tubes to 20-21 cm in women and 22-23 cm in men, especially when high ambient noise precludes accurate auscultation (such as in emergency situations or helicopter transport). The highest sensitivity and specificity for ruling out endobronchial intubation, however, is achieved by combining tube depth, auscultation of the lungs, and observation of symmetrical chest movements.

Trial registration NCT01232166.


  • Funding: This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

  • Contributors: CS, PK, and SCK contributed to the design of the trial. CS, PK, SCK, and DIS contributed to the interpretation of the results and writing of the manuscript. AL, AS, CG, SCK, CW, and CS contributed to the recruitment of patients, data collection, and management of the trial. CS, DIS, and HH contributed to the statistical analysis. CS is the guarantor.

  • Competing interests: All authors have completed the Unified Competing Interest form at (available on request from the corresponding author) and declare: no support from any organisation for the submitted work; no financial relationships with any organisations that might have an interest in the submitted work in the previous 3 years; no other relationships or activities that could appear to have influenced the submitted work.

  • Ethical approval: The study was approved by the ethics committee of the Medical University of Vienna and written informed consent was obtained by independent investigators.

  • Data sharing: No additional data available.

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