I. Hodzovic

A comparison of simulated difficult intubation with multiple-use and single-use bougies in a manikin.

Summary In a randomised cross‐over study, 20 anaesthetists attempted to place a multiple‐ or single‐use bougie in the trachea of a manikin, in which a grade 3 Cormack and Lehane laryngoscopic view was simulated. The anaesthetists made two attempts at placement with each bougie and were blinded to success (tracheal placement) or failure (oesophageal placement). The success rates for the first attempts with the multiple‐ and single‐use bougies were 85 and 15%, respectively [mean (95% CI) difference between the two bougies 70% (40–84%); p < 0.001]. The success rates for the second attempts were similar to those for the first attempts with both bougies. There is an increased risk of failure to intubate the trachea when using a single‐use bougie, and this must be weighed against the unquantified risk of cross‐infection from prions when using a multiple‐use bougie.

Evaluation of clinical effectiveness of the Frova single-use tracheal tube introducer.

A prospective observational study design was used to evaluate the clinical effectiveness of the Frova single‐use tracheal tube introducer. Data were collected from 203 patients. Consultants and trainee anaesthetists completed 61 (30%) and 142 (70%) forms respectively, when the Frova introducer was used. It was successfully placed in the trachea in 194/203 (96%) of patients with two attempts at placement by the first clinician. The first clinician failed to either pass the Frova introducer or railroad the tube in six (3%) and 10 (5%) of the 203 patients respectively. The success rate by the first clinician was significantly influenced by the laryngeal view obtained (p < 0.0001). There was only one failure to place the Frova introducer in the trachea by either the first or second clinician. Airway trauma was detected in 11/203 (5%) patients. In six of these 11 patients blood was detected on tracheal suction; ‘distal hold up’ was elicited in five of these six. The Frova introducer has a high success rate for tracheal placement but has noteworthy potential to produce airway trauma.

Prehospital airway management in Ambulance Services in the United Kingdom

A postal survey of the 38 Ambulance Services in the United Kingdom was undertaken to find out what equipment is provided for paramedic crews to aid tracheal intubation and to confirm tracheal placement. The response rate to our survey was 100%. Fourteen (37%) ambulance services provided neither stylet nor bougie to facilitate difficult intubation. The laryngeal mask airway was available to 15 (40%) ambulance services. Seventeen (45%) ambulance services had use of a needle cricothyroidotomy set. Twenty‐nine (76%) ambulance services had no type of device other than a stethoscope to confirm tracheal tube placement. This survey showed wide variations in the equipment for airway management available to paramedic crews in the United Kingdom. We recommend provision of a standard set of airway management equipment to all paramedic crews in the United Kingdom together with introduction of appropriate training programmes.

'From darkness into light': time to make awake intubation with videolaryngoscopy the primary technique for an anticipated difficult airway?

733–8. 29. Bilgen S, Koner O, Karacay S, sancar NK, Kaspar EC, Sozubir S. Effect of ketamine versus alfentanil following midazolam in preventing emergence agitation in children after sevoflurane anaesthesia: A prospective randomized clinical trial. Journal of International Medical Research 2014; 42: 1262–71. 30. Abu-Shahwan I, Chowdary K. Ketamine is effective in decreasing the incidence of emergence agitation in children undergoing dental repair under sevoflurane general anesthesia. Pediatric Anesthesia 2007; 17: 846–50. 31. Ozcan A, Kaya AG, Ozcan N, et al. Effects of ketamine and midazolam on emergence agitation after sevoflurane anaesthesia in children receiving caudal block: a randomized trial. Brazilian Journal of Anesthesiology 2014; 64: 377–81. 32. Pickard A, Davies P, Birnie K, Beringer R. Systematic review and meta-analysis of the effect of intraoperative a2-adrenergic agonists on postoperative behaviour in children. British Journal of Anaesthesia 2014; 112: 982–90. 33. Yang S, Lee H. A dose-finding study of preoperative intravenous dexmedetomidine in children’s emergence delirium after epiblepharon surgery. European Journal of Ophthalmology 2014; 24: 417–23. 34. Yuen VM, Hui TW, Irwin MG, et al. A randomised comparison of two intranasal dexmedetomidine doses for premedication in children. Anaesthesia 2012; 67: 1210–6. 35. Kim J, Kim SY, Lee JH, Kang YR, Koo BN. Low-dose dexmedetomidine reduces emergence agitation after desflurane anaesthesia in children undergoing strabismus surgery. Yonsei Medical Journal 2014; 55: 508– 16. 36. Patel A, Davidson M, Tran MC, et al. Dexmedetomidine infusion for analgesia and prevention of emergence agitation in children with obstructive sleep apnea syndrome undergoing tonsillectomy and adenoidectomy. Anesthesia and Analgesia 2010; 111: 1004–10. 37. Shukry M, Clyde MC, Kalarickal PL, Ramadhyani U. Does dexmedetomidine prevent emergence delirium in children after sevoflurane-based general anesthesia? Pediatric Anesthesia 2005; 15: 1098–104. 38. Chen JY, Jia JE, Liu TJ, Qin MJ, Li WX. Comparison of the effects of dexmedetomidine, ketamine, and placebo on emergence agitation after strabismus surgery in children. Canadian Journal of Anesthesia 2013; 60: 385–92. 39. Ali MA, Abdellatif AA. Prevention of sevoflurane related emergence agitation in children undergoing adenotonsillectomy: a comparison of dexmedetomidine and propofol. Saudi Journal of Anesthesiology 2013; 7: 296–300. 40. Bong CL, Lim E, Allen JC, et al. A comparison of single-dose dexmedetomidine or propofol on the incidence of emergence delirium in children undergoing general anaesthesia for magnetic resonance imaging. Anaesthesia 2015; 70: 393–9. 41. Abdulatif M, Ahmed A, Mukhtar A, Badawy S. The effect of magnesium sulphate infusion on the incidence and severity of emergence agitation in children undergoing adenotonsillectomy using sevoflurane anaesthesia. Anaesthesia 2013; 68: 1045–52. 42. Fregene T. Magnesium sulphate and postoperative agitation in children: an analgesic effect? Anaesthesia 2014; 69: 187–8. 43. Bae JH, Koo BW, Kim SJ, et al. The effects of midazolam administered postoperatively on emergence agitation in pediatric strabismus surgery. Korean Journal of Anesthesiology 2010; 58: 45–9. 44. Hallen J, Rawal N, Gupta A. Postoperative recovery following outpatient pediatric myringotomy: a comparison between sevoflurane and halothane. Journal of Clinical Anesthesia 2001; 13: 161–6. 45. Welborn L, hannallah R, Norden J, et al. Comparison of emergence and recovery characteristics of sevoflurane, desflurane and halothane in pediatric ambulatory patients. Anesthesia and Analgesia 1996; 83: 917–20.

Introducing new anaesthetic equipment into clinical practice

A recent editorial in the British Medical Journal posed the question ‘How can we regulate medicines better?’ [1]. The authors concluded that European licensing regulations gave precedence to the interests of the drug companies rather than to the needs of the patients and doctors. There is a similar debate occurring in anaesthesia on the introduction of new medical devices into clinical practice: manufacturers are allowed to market many devices without being required to provide evidence of their efficacy [2, 3]. We recently published a paper on the Frova introducer in Anaesthesia [4]. During the review process, we were asked to provide ‘a statement outlining where you feel we should go comparing existing devices’. Here we outline our proposals to address this issue.

To shape or not to shape…Simulated bougie‐assisted difficult intubation in a manikin

Summary Thirty anaesthetists attempted to place a derived ‘optimal’ curve bougie or a straight bougie in the trachea of a manikin, in a randomised cross‐over study. A Grade 3 Cormack and Lehane laryngoscopic view was simulated. The anaesthetists were blinded to success (tracheal placement) or failure (oesophageal placement). The success rates with the curved and straight bougies were 83 and 7%, respectively, giving a difference (95% confidence interval) of 77% (54–87%) between the two bougies (p < 0.0001). On a separate occasion, under identical laboratory conditions, 30 anaesthetists attempted to place a straight coudé (angled)‐tipped bougie or a straight straight‐tipped bougie in the trachea of a manikin. The success rates with the coudé‐ and straight‐tipped bougies were 43 and 0%, respectively, giving a difference (95% confidence interval) of 43% (21–61%) between the two bougies (p < 0.001). These results suggest that bougies used to facilitate difficult intubation should be curved and have a coudé tip.

Evaluation of tracheal tube introducers in simulated difficult intubation

In a randomised cross‐over study, 72 anaesthetists attempted to place Pro‐Breathe, new Portex, and Frova single‐use tracheal tube introducers and an Eschmann multiple‐use introducer in the trachea of a manikin set to simulate a grade 3 laryngeal view. Successful placement (proportion, 95% confidence interval) of either the Frova (78%, 67–86%) or the Eschmann introducer (64%, 52–74%) was significantly more likely (p < 0.0001) than with the Pro‐Breathe (4%, 1–12%) or the new Portex introducer (13%, 7–22%). The difference between the success rates for the Frova and the Eschmann introducers (p = 0.08) was not significant. A separate experiment revealed that the peak force that could be exerted by the Pro‐Breathe, new Portex and Frova single‐use introducers were three to six times greater than that which could be exerted by the Eschmann introducer (p < 0.0001). The single‐use introducers are more likely to cause tissue trauma during placement, particularly if held close to the tip.

Airway trauma caused by the Airtraq® laryngoscope

drying, helping subsequent dressings to remain in place. Examining the OpSite product (catalogue #66004978) (Smith & Nephew, Hull, UK) it clearly states under contraindications and precautions, printed on the product that it should not be used with plastic intravascular devices. I have contacted Smith & Nephew in an attempt to clarify this matter. The ethyl acetate and acetone contained in the spray can react with the device and lead to degradation of the plastic in the device. The advice from their Product Information Advisor is that the use of this product is contraindicated with all types of plastic devices. This includes epidural catheters. The term ‘plastic’ in general can encompass a large number of substances and chemically comprises various organic compounds which have undergone polymerisation. Plastics can be thermoplastic (soften with heat and harden with cooling) and thermoset (hardened by heat). Examples of well known thermoplastics are Acrylo-nitrile (Nylon), Polyethylene (Polythene), Poly Vinyl Acetate (PVA), Poly Vinyl Chloride (PVC) and Polytetrafluoroethylene (PTFE, Teflon). Epidural catheters appear to contain different plastics depending on the manufacturer. B. Braun (Melsungen, Germany) and Smiths Medical (Smiths Group, London, UK) are examples of manufacturers of epidural catheters which can be found in the UK and have details freely available on the internet. Portex catheters (Smiths Medical) can be made of Nylon (polyamide) or Teflon (PTFE) whilst B. Braun detail that their catheters contain a unique formulation of polyamide Nylon with varying stiffness depending on the exact product [1, 2]. I have had some correspondence regarding Polytetrafluoroethylene (PTFE, Teflon) with Smith & Nephew. It is a widely used high performance plastic with favourable chemical and heat resistance properties. With regards to this particular plastic the problem may not necessarily be with PTFE but with other polymers mixed with it to give the tubing desirable characteristics such as bend and stretch. These other added polymers are more likely to be dissolved by the solvents in the OpSite spray and could then cause degradation problems. Smith & Nephew have understandably taken the stance that without a full chemical breakdown of the subject tubing they cannot guarantee its safety with their product. I am not aware of the exact clinical consequences for the patient as a result of this chemical reaction but I think this contraindication is certainly something to be aware of the next time an anaesthetic assistant offers this product for use after a central line or epidural insertion. Given the manufacturer’s contraindications this product should no longer be used in these situations.

Bougie‐assisted difficult airway management in a manikin – the effect of position held on placement and force exerted by the tip*

In a randomised cross‐over study, 50 anaesthetists attempted to place a multiple‐use bougie in the trachea of a manikin, when holding it at either 20 cm or 30 cm from the tip. A grade 3 laryngoscopic view was simulated. The anaesthetists were blinded to success (tracheal placement) or failure (oesophageal placement). The success rates when held at 20 and 30 cm distance from the tip were 68 and 62%, respectively (p = 0.55). In a separate experiment, multiple and single‐use bougies were held at four different positions and pressed onto a disc attached to a force transducer. The peak force exerted by the single‐use bougies was two to three times greater than that which could be exerted by the multiple‐use bougies (p < 0.0001). Holding the bougie at either 20 or 30 cm distance from the tip is unlikely to influence bougie placement. The single‐use bougie is much more likely to cause trauma to tissue during placement, particularly if held close to the tip.

Bougie-related airway trauma: dangers of the hold-up sign†

The bougie is a popular tool in difficult intubations. The hold‐up sign is used to confirm tracheal placement of a bougie. This study aimed to establish the potential for airway trauma when using this sign with an Eschmann re‐usable bougie or a Frova single‐use bougie. Airways were simulated using a manikin (hold‐up force) and porcine lung model (airway perforation force). Mean (SD) hold‐up force (for airway lengths over the range 25–45 cm) of 1.0 (0.4) and 5.2 (1.1) N were recorded with the Eschmann and Frova bougies, respectively (p < 0.001). The mean (SD) force required to produce airway perforation was 0.9 (0.2) N with the Eschmann bougie and 1.1 (0.3) N with the Frova bougie (p = 0.11). It is possible to apply a force at least five times greater than the force required to produce significant trauma with a Frova single‐use bougie. We recommend that the hold‐up sign should no longer be used with single‐use bougies. Clinicians should be cautious when eliciting this sign using the Eschmann re‐usable bougie.