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• The downside of taking the tube
  Andrew M. Mason
  Published on: 29 April 2016

• Published on: 29 April 2016

  The downside of taking the tube

  • Andrew M. Mason, Immediate Care Physician

  Dear Editor,

  After reviewing the 2004 paper by Shy et al. in which the authors concluded that faster intubation times may increase odds of survival in prehospital cardiac arrest, Professor Woollard poses the question, "Perhaps it is time to reconsider the value of the gold standard of airway management in a more positive light?"[1]. In this retrospective cohort study of 693 patients, the authors compared "quick...

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  Dear Editor,

  After reviewing the 2004 paper by Shy et al. in which the authors concluded that faster intubation times may increase odds of survival in prehospital cardiac arrest, Professor Woollard poses the question, "Perhaps it is time to reconsider the value of the gold standard of airway management in a more positive light?"[1]. In this retrospective cohort study of 693 patients, the authors compared "quick intubation" (< or = 12 minutes) with "slow intubation" (> or = 13 minutes) and found survival rates of 46% in the quick intubation group compared with 23% for slow intubation, with an odds ratio of survival of 0.42 in the quick intubation group when the results were adjusted for possible confounding factors.

  Woollard's suggestion that the results of this study should have us all reaching enthusiastically for our tracheal tubes fails to take into account the significant and growing body of evidence to the contrary. Patients die from a failure to oxygenate and a failure to ventilate, not from a failure to intubate, and there are a number of intermediate airway devices, such as the laryngeal mask airway (LMA), which oxygenate and ventilate patients perfectly adequately. Furthermore, it has been shown quite clearly that competency in LMA insertion can be achieved readily by non-anaesthetists[2][3][4], with the LMA providing better ventilation than a bag-valve-mask device, and speedier deployment with higher levels of first-time placement and skill retention over time than is found with the endotracheal tube.

  In a seminal prospective audit published in 1994[5], the effect of withdrawing the resident anaesthesiologist from the CPR team in a 407-bed UK hospital was investigated over a 12-month period, nursing staff having been trained in the use of the LMA for initial management of the airway. The data were compared with those from the previous year (shown here in parenthesis). During the audit period there were 115(79) cardiac arrest calls, with the LMA being used in 64(2) cases and the tracheal tube in 20(57). Return of spontaneous circulation occurred in 61%(36%) of patients, and there were no instances of failure to secure the immediate airway. In a further study from the UK published in 2005[6], paramedics trained in the use of the LMA and ETT were asked to secure the airway in patients undergoing routine anaesthesia. The authors found that, even under optimal conditions, 30% of attempts at tracheal intubation by paramedics were unsuccessful, whereas, insertion of a single-use laryngeal mask was successful in 80% of the failed intubation cases. The authors concluded that a disposable laryngeal mask has a higher success rate in securing the airway and, overall, secures the airway more reliably than endotracheal intubation. The high rates of unrecognised endotracheal tube misplacement by paramedics (16.7% in the oesophagus, 8.3% in the hypopharynx) in one US study of prehospital intubation published in 2001[7] can hardly be said to represent any sort of 'gold standard' of airway care.

  The paper cited by Woollard looked at just one type of intervention (endotracheal intubation) delivered at different stages (early and late) of the dying process (cardiac arrest), and it is hardly surprising that the early intervention group came out on top. Woollard’s suggestion that this paper justifies the continued practice of prehospital intubation by direct laryngoscopy is, quite frankly, spurious. A carefully designed prospective crossover trial of the LMA versus the endotracheal tube by UK paramedics is urgently needed to try to answer important questions about the best way of managing the airway in prehospital care. Perhaps Professor Woollard would be willing to help facilitate such a study?

  References

  1] Woollard M. Early endotracheal intubation may improve outcome following out of hospital cardiac arrest. Emerg Med J 2006; 23: 482. doi:10.1136/emj.2006.036277.

  [2] Pennant JH, Walker MB. Comparison of the endotracheal tube and laryngeal mask in airway management by paramedical personnel. Anesth Analg 1992;74:531-4.

  [3] Davies PRF, Tigh SQ, Greenslade GL, Evans GH. Laryngeal mask airway and tracheal tube insertion by unskilled personnel. Lancet 1990;336:977-9.

  [4] Reinhart DJ. Laryngeal mask airway (LMA) vs endotracheal tube (ETT) placement by paramedics, respiratory therapists and registered nurses. Anesthesiology 1993;79:A1058(abstract).

  [5] Verghese C, Prior-Willeard PF, Baskett PJF. Immediate management of the airway during cardiopulmonary resuscitation in a hospital without a resident anaesthesiologist. Eur J Emerg Med 1994;1(3):123-5.

  [6] Deakin CD, Peters R, Tomlinson P, Cassidy M. Securing the prehospital airway: a comparison of laryngeal mask insertion and endotracheal intubation by UK paramedics. Emerg Med J 2005;22:66-67.

  [7] Katz SH, Falk JL. Misplaced endotracheal tubes by paramedics in an urban emergency medical services system. Ann Emerg Med 2001;37:62-4.

  CONFLICT OF INTEREST STATEMENT: AMM is Adviser in Prehospital Care to Intavent Orthofix Ltd, distributor of the LMA in the UK. This is an unsalaried position, but AMM has received occasional payment from the company for advisory work in connection with use of the LMA and iLMA in the prehospital environment.

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  Conflict of Interest:
  None declared.

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