A way of improving glottic visualisation when attempting fibreoptic intubation is for an assistant to perform a jaw thrust manoeuvre. This is nicely demonstrated in a video on the New England Journal website. However my retrieval medicine colleague and anaesthetist Dr Anthony Lewis pointed out the following situation and its solution:
What if they are a ‘difficult airway’ and you the jaw can’t move? Get your Magills forceps, grab the tongue and pull the tongue out. Very nice!
A colleague told me about a cricoid pressure paper I would otherwise have missed, since I don’t normally check out the International Journal of Obstetric Anaesthesia. This was a multicentre observational study in Malawi, in which 30 women (of 4891 general anaesthetics) vomited or regurgitated during induction of anaesthesia, in 24 of whom cricoid pressure was applied. 11 of the 77 deaths that occurred were associated with regurgitation, in 10 of which regurgitation contributed to the death. Nine of these 11 mothers who died had had cricoid pressure applied. The incidence of regurgitation was lower, but not significantly so, among those who did not have cricoid pressure applied. Not sure why it took nine years to publish this work.
BACKGROUND: Cricoid pressure is a routine part of rapid-sequence induction of general anaesthesia in obstetrics, but its efficacy in saving life is difficult to ascertain.
METHODS: As part of a prospective observational study of caesarean sections performed between January 1998 and June 2000 in 27 hospitals in Malawi, the anaesthetist recorded whether cricoid pressure was applied, the method of anaesthesia, the use of endotracheal intubation, the occurrence and timing of regurgitation and any other pre- or intra-operative complications. Logistic regression was used to assess the effect of cricoid pressure, type of anaesthetic and pre-operative complications on vomiting/regurgitation and death.
RESULTS: Data were collected for 4891 general anaesthetics that involved intubation. Cricoid pressure was applied in 61%; 139 women vomited or regurgitated, but only 30 on induction of anaesthesia, in 24 of whom cricoid pressure was applied. There were 77 deaths, 11 of which were associated with regurgitation, in 10 of which regurgitation contributed to the death. Nine of the 11 mothers had cricoid pressure applied. Only one died on the table, the rest postoperatively. All those who died had preoperative complications.
CONCLUSION: This study does not provide any evidence for a protective effect of cricoid pressure as used in this context, in preventing regurgitation or death. Preoperative gastric emptying may be a more effective measure to prevent aspiration of gastric contents.
Life-saving or ineffective? An observational study of the use of cricoid pressure and maternal outcome in an African setting
Int J Obstet Anesth. 2009 Apr;18(2):106-10
Single-use metal laryngoscope blades were compared in a randomised trial in the pre-hospital setting by French SAMU physicians. First-pass intubation success (defined as one advancement of the tube in the direction of the glottis during direct laryngoscopy) was similar between conventional and disposable metal blades.
STUDY OBJECTIVE: Emergency tracheal intubation is reported to be more difficult with single-use plastic than with reusable metal laryngoscope blades in both inhospital and out-of-hospital settings. Single-use metal blades have been developed but have not been compared with conventional metal blades. This controlled trial compares the efficacy and safety of single-use metal blades with reusable metal blades in out-of-hospital emergency tracheal intubation.
METHODS: This randomized controlled trial was carried out in France with out-of-hospital emergency medical units (Services de Médecine d’Urgence et de Réanimation). This was a multicenter prospective noninferiority randomized controlled trial in adult out-of-hospital patients requiring emergency tracheal intubation. Patients were randomly assigned to either single-use or reusable metal laryngoscope blades and intubated by a senior physician or a nurse anesthetist. The primary outcome was first-pass intubation success. Secondary outcomes were incidence of difficult intubation, need for alternate airway devices, and early intubation-related complications (esophageal intubation, mainstem intubation, vomiting, pulmonary aspiration, dental trauma, bronchospasm or laryngospasm, ventricular tachycardia, arterial desaturation, hypotension, or cardiac arrest).
RESULTS: The study included 817 patients, including 409 intubated with single-use blades and 408 with a reusable blade. First-pass intubation success was similar in both groups: 292 (71.4%) for single-use blades, 290 (71.1%) for reusable blades. The 95% confidence interval (CI) for the difference in treatments (0.3%; 95% CI -5.9% to 6.5%) did not include the prespecified inferiority margin of -7%. There was no difference in rate of difficult intubation (difference 3%; 95% CI -7% to 2%), need for alternate airway (difference 4%; 95% CI -8% to 1%), or early complication rate (difference 3%; 95% CI -3% to 8%).
CONCLUSION: First-pass out-of-hospital tracheal intubation success with single-use metal laryngoscopy blades was noninferior to first-pass success with reusable metal laryngoscope blades.
Out-of-Hospital Tracheal Intubation With Single-Use Versus Reusable Metal Laryngoscope Blades: A Multicenter Randomized Controlled Trial
Ann Emerg Med. 2011 Mar;57(3):225-31
This short but punchy lecture by Reuben Strayer of the excellent Emergency Medicine Updates blog addresses some dogma and tells it like it is….
Rocuronium vs. Succinylcholine from reuben strayer on Vimeo.
Since making the video the article about oxygen desaturation time came out which contributes some further weight to the roc argument.
While I am gradually being persuaded rocuronium might after all be a better choice than suxamethonium for rapid sequence intubation in critically ill patients- partly due to its relative preservation of apnoea time before desaturation in elective anaesthesia patients1 – I don’t believe that the existence and availability of its reversal agent, sugammadex, should really sway us in critical care. After all, we’re usually committed to getting an airway of some description (tracheal tube, supraglottic airway, or cricothyrotomy), and the relatively short duration of suxamethonium has never allowed me to ‘wake someone up and cancel the case’ in a critical care scenario. In fact, with sux, even healthy patients will desaturate before it wears off 2-4 if one is unable to intubate or ventilate.
But could we give sugammadex and reverse the rocuronium in time to save the patient in a can’t intubate/can’t ventilate (CICV) situation? This was tested in a simulation that studied the total time taken for anaesthetic teams to prepare and administer sugammadex from the time of their initial decision to use the drug5. The mean (SD) total time to administration of sugammadex was 6.7 (1.5) min, following which a further 2.2 min (giving a total 8.9 min) should be allowed to achieve a train-of-four ratio of 0.9. Four (22%) teams gave the correct dose, 10 (56%) teams gave a dose that was lower than recommended.
A reply to this article6 recommended some steps to speed up and improve the process:
There are of course rare situations where sugammadex can be a nuisance – it hangs around in renal failure and a recent case report 7described rocuronium (50mg followed by 30mg, patient weight not stated) failing to work on an elderly man who had received sugammadex 16 hours earlier! The authors of this case report state that in healthy patients, the mean cumulative percentage of sugammadex excreted in the urine over 24 h is 48–86%; therefore, a period of 24 h is recommended before a second administration of rocuronium. However, a good dose of rocuronium (1.2 mg/kg) should be effective after sugammadex reversal in previously healthy patients, but a study showed onset was slower and duration shorter if the second dose of rocuronium was given within 25 minutes of the sugammadex8.
So what are the take home points here? For me, the issues are:
1. Effect of suxamethonium vs rocuronium on onset of oxygen desaturation during apnoea following rapid sequence induction
Anaesthesia. 2010 Apr;65(4):358-61
2. Critical hemoglobin desaturation will occur before return to an unparalyzed state following 1 mg/kg intravenous succinylcholine.
Anesthesiology. 1997 Oct;87(4):979-8
3. Hemoglobin desaturation after succinylcholine-induced apnea: a study of the recovery of spontaneous ventilation in healthy volunteers.
Anesthesiology. 2001 May;94(5):754-9
4. Succinylcholine dosage and apnea-induced hemoglobin desaturation in patients
Anesthesiology. 2005 Jan;102(1):35-40
5. Can sugammadex save a patient in a simulated ‘cannot intubate, cannot ventilate’ situation?
Anaesthesia. 2010 Sep;65(9):936-41
6. Can sugammadex save a patient in a simulated ‘cannot intubate, cannot ventilate’ situation?
Anaesthesia. 2011 Mar;66(3):223-4
7. Unexpected failure of rocuronium-mediated neuromuscular blockade
Anaesthesia. 2011 Jan;66(1):58-9
8. Repeat dosing of rocuronium 1.2 mg kg−1 after reversal of neuromuscular block by sugammadex 4.0 mg kg−1 in anaesthetized healthy volunteers: a modelling-based pilot study
Br J Anaesth. 2010 Oct;105(4):487-92
9. Comparison of Succinylcholine and Rocuronium for First-attempt Intubation Success in the Emergency Department
Acad Emerg Med. 2011;18:11-14
10. Critical hemoglobin desaturation can be delayed by apneic diffusion oxygenation
Anesthesiology. 1999 Jan;90(1):332-3
A blinded randomised controlled trial of rocuronium versus saline in anaesthetised patients demonstrated that mask ventilation was easier in paralysed patients.
The authors comment on the implications of this finding:
‘Our finding that neuromuscular blockade facilitates mask ventilation has important implications for the practice of managing difficult or impossible mask ventilation after administration of these drugs. Options in this case include returning to spontaneous ventilation, tracheal intubation, placement of a supraglottic airway device or obtaining emergency invasive airway access. In most cases, returning to spontaneous ventilation is not practical in a reasonable time frame, leaving tracheal intubation, supraglottic airway placement or emergency invasive airway access as the only feasible choices. Considerable evidence exists indicating that neuromuscular blockade facilitates tracheal intubation; and since our data further indicate that neuromuscular blockade facilitates mask ventilation, it follows that administering neuromuscular blockade is an advantage, rather than a hindrance when given early in a case of unrecognised difficult mask ventilation.‘
ABSTRACT
We wished to test the hypothesis that neuromuscular blockade facilitates mask ventilation. In order reliably and reproducibly to assess the efficiency of mask ventilation, we developed a novel grading scale (Warters scale), based on attempts to generate a standardised tidal volume. Following induction of general anaesthesia, a blinded anaesthesia provider assessed mask ventilation in 90 patients using our novel grading scale. The non-blinded anaesthesiologist then randomly administered rocuronium or normal saline. After 2 min, mask ventilation was reassessed by the blinded practitioner. Rocuronium significantly improved ventilation scores on the Warters scale (mean (SD) 2.3 (1.6) vs 1.2 (0.9), p<0.001). In a subgroup of patients with a baseline Warters scale value of >3 (i.e. difficult to mask ventilate; n=14), the ventilation scores also showed significant improvement (4.2 (1.2) vs 1.9 (1.0), p=0.0002). Saline administration had no effect on ventilation scores. Our data indicate that neuromuscular blockade facilitates mask ventilation. We discuss the implications of this finding for unexpected difficult airway management and for the practice of confirming adequate mask ventilation before the administration of neuromuscular blockade.
The effect of neuromuscular blockade on mask ventilation
Anaesthesia. 2011 Mar;66(3):163-7
French pre-hospital physicians included the Easytube, which is similar to the Combitube, in their difficult airway algorithm. They describe the insertion method as:
“ ..inserted blindly, the patient’s head must be in neutral position. Manually opening the patient’s mouth and pressing the tongue gently toward the mandible, the tube is inserted parallel to the frontal axis of the patient until the proximal black ring mark is positioned at the level of the incisors. If the EzT is inserted blindly, the tip is likely to be positioned in the esophagus with a probability of more than 95% [3]. Ventilation of the patient should be performed using a colored lumen, and the transparent lumen can then be used to insert a gastric tube or to drain gastric contents.”
The authors suggest that the main advantages of the Ezt are: shorter insertion time for Ezt than for ETI, better protection against aspiration than a laryngeal mask and the possibility of blind insertion of the Ezt in patients trapped in a sitting position.
BACKGROUND: Securing the airway in emergency is among the key requirements of appropriate prehospital therapy. The Easytube (Ezt) is a relatively new device, which combines the advantages of both an infraglottic and supraglottic airway.
AIMS: Our goal was to evaluate the effectiveness and the safety of use of Ezt by emergency physicians in case of difficult airway management in a prehospital setting with minimal training.
METHODS: We performed a prospective multi-centre observational study of patients requiring airway management conducted in prehospital emergency medicine in France by 3 French mobile intensive care units from October 2007 to October 2008.
RESULTS: Data were available for 239 patients who needed airway management. Two groups were individualized: the “easy airway management” group (225 patients; 94%) and the “difficult airway management” group (14 patients; 6%). All patients had a successful airway management. The Ezt was used in eight men and six women; mean age was 64 years. It was used for ventilation for a maximum of 150 min and the mean time was 65 min. It was positioned successfully at first attempt, except for two patients, one needed an adjustment because of an air leak, and in the other patient the Ezt was replaced due to complete obstruction of the Ezt during bronchial suction.
CONCLUSION: The present study shows that emergency physicians in cases of difficult airway management can use the EzT safely and effectively with minimal training. Because of its very high success rate in ventilation, the possibility of blind intubation, the low failure rate after a short training period. It could be introduced in new guidelines to manage difficult airway in prehospital emergency.
The Easytube for airway management in prehospital emergency medicine
Resuscitation. 2010 Nov;81(11):1516-20
I was lucky enough to be interviewed by the amazing Scott Weingart, an emergency medicine intensivist who runs the spectacular EMcrit podcast. We covered some stuff on pre-hospital airway management, physicians in pre-hospital care, and I had a rant about ‘scoop and run’ versus ‘stay and play’. Worryingly, Scott is keeping back some audio footage for a later podcast, probably containing an even bigger rant about things like ATLS.
Click the image to be taken to the EMcrit site where you can listen to the podcast.
Flying Doctor Minh Le Cong describes the profile and success rates of emergency endotracheal intubation conducted by the Queensland Royal Flying Doctor Service aeromedical retrieval team, comprising a doctor and flight nurse. It would be interesting to know how many more patients have been added to the registry since this was submitted. An important contribution to the literature in retrieval medicine.
Objective To describe the profile and success rates of emergency endotracheal intubation conducted by the Queensland Royal Flying Doctor Service aeromedical retrieval team comprising a doctor and flight nurse.
Method Each intubator completed a study questionnaire at the time of each intubation for indications, complications, overall success, drugs utilised and deployment of rescue airway devices/adjuncts.
Results 76 patients were intubated; 72 intubations were successful. None required surgical airway and three were managed with laryngeal mask airways; the remaining failure was managed with simple airway positioning for transport. There were two cardiac arrests during intubation. Thiopentone and suxamethonium were the predominant drugs used to facilitate intubation.
Conclusion Despite a low rate of endotracheal intubation, the high success rate was similar to other aeromedical organisations’ published airway data. This study demonstrates the utility of the laryngeal mask airway device in the retrieval and transport setting, in particular for managing a failed intubation.
Flying doctor emergency airway registry: a 3-year, prospective, observational study of endotracheal intubation by the Queensland Section of the Royal Flying Doctor Service of Australia
Emerg Med J. 2010 Sep 15. [Epub ahead of print]
Those interested in learning more about this registry, including how often capnography was used, more information about the asystolic arrests, and whether they tried a blind digital intubation, can check this link to a presentation about the registry.
Dr Rich Levitan has made an enormous contribution to the science and practice of emergency airway management, as his bibliography demonstrates. In a new article in Emergency Physicians Monthly entitled ‘Demystifying Pediatric Laryngoscopy’, Rich covers some great tips for optimising laryngoscopic view in kids.
Check this excerpt out for an example:
“During laryngoscopy in infants the epiglottis and uvula are often touching; the epiglottis may be located within an inch of the mouth. Often the epiglottis lies against the posterior pharynx, and it is critical to have a Yankauer to dab the posterior pharynx as the laryngoscope is advanced. Hyperextension of the head pushes the base of tongue and epiglottis backwards against the posterior pharyngeal wall, and makes epiglottis identification more difficult”
Gems like this come thick and fast when you hear or read what Rich has to say. Seven years ago I was left reeling after finishing his ‘Airway Cam Guide to Intubation and Practical Emergency Airway Management‘ which profoundly influenced the way I practice and teach emergency airway skills, including on the Critical Care for Emergency Physicians course.
I’ve finally gotten round to booking a place on one of his courses in March in Baltimore. I’ll let you know how it goes. In the mean time, I’d like to point you toward his training videos as a great educational resource, like this one that demonstrates for novice laryngoscopists the difference between the appearances of trachea and oesophagus, the former having recognisable, defined posterior cartilagenous structures:
Demystifying Pediatric Laryngoscopy
Emergency Physicians Monthly January 19, 2011