Tag Archives: RSI

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RSI complications increase with intubation difficulty

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A substudy of a large randomised controlled trial comparing etomidate with ketamine for RSI in the pre-hospital environment, emergency department, and intensive care unit examined immediate complication rates in relation to the intubation difficulty scale score (IDS).
They used the 7-criteria IDS previously developed and evaluated. The variables included in the IDS are as follows:

  1. the number of attempts excluding the first;
  2. the number of extra operators;
  3. the number of additional techniques utilised;
  4. the Cormack grade (0–3 points, grade 1 giving no IDS points);
  5. the intensity of lifting force required (0 points if normal, 1 point if increased);
  6. the need to apply external laryngeal pressure (0 or 1 point, application of cricoid pressure (Sellick manoeuvre) does not alter the score)
  7. vocal cord position (abduction, 0 points; adduction, 1 point). Each criterion was scored and recorded by the physician who performed the procedure.

The sum gives the IDS score, and a score of 0 indicates an easy tracheal intubation at the first attempt by a single operator using a single technique, with a good view of the glottis and abducted vocal cords. Intubation was considered difficult if the score was greater than 5.
There was a positive linear relationship between IDS score and complication rate, and difficult intubation appeared to be a significant independent predictor of death.

OBJECTIVES: To evaluate the association between emergency tracheal intubation difficulty and the occurrence of immediate complications and mortality, when standardised airway management is performed by emergency physicians.

METHODS: The present study was a substudy of the KETAmine SEDation (KETASED) trial, which compared morbidity and mortality after randomisation to one of two techniques for rapid sequence intubation in an emergency setting. Intubation difficulty was measured using the intubation difficulty scale (IDS) score. Complications recognised within 5min of endotracheal intubation were recorded. We used multivariate logistic regression analysis to determine the factors associated with the occurrence of complications. Finally, a Cox proportional hazards regression model was used to examine the association of difficult intubation with survival until 28 days.

RESULTS: A total of 650 patients were included, with mean age of 55±19 years. Difficult intubation (IDS >5) was recorded in 73 (11%) patients and a total of 248 complications occurred in 192 patients (30%). Patients with at least one complication had a significantly higher median IDS score than those without any complications. The occurrence of a complication was independently associated with intubation difficulty (odds ratio 5.9; 95% confidence interval (CI) [3.5;10.1], p<0.0001) after adjustment on other significant factors. There was a positive linear relationship between IDS score and complication rate (R(2)=0.83; p<0.001). The Cox model for 28-day mortality indicated that difficult intubation (hazard ratio 1.59; 95%CI [1.04;2.42], p=0.03) was a significant independent predictor of death.

CONCLUSION: Difficult intubation, measured by the IDS score, is associated with increased morbidity and mortality in patients managed under emergent conditions.

Morbidity related to emergency endotracheal intubation—A substudy of the KETAmine SEDation trial
Resuscitation. 2011 May;82(5):517-22

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Pre-hospital Airtraq use often failed

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The Airtraq seems nifty when you try it on a manikin, but until now the question of whether it would be a useful pre-hospital tool was unanswered. This Austrian study provides helpful data:

OBJECTIVES: The optical Airtraq laryngoscope (Prodol Meditec, Vizcaya, Spain) has been shown to have advantages when compared with direct laryngoscopy in difficult airway patients. Furthermore, it has been suggested that it is easy to use and handle even for inexperienced advanced life support providers. As such, we sought to assess whether the Airtraq may be a reliable alternative to conventional intubation when used in the prehospital setting.
DESIGN, SETTING, AND PATIENTS: Prospective, randomized control trial in emergency patients requiring endotracheal intubation provided by anesthesiologists or emergency physicians responding with an emergency medical service helicopter or ground unit associated with the Department of Anesthesiology, General Hospital, Wiener Neustadt, Austria.
MEASUREMENTS AND MAIN RESULTS: During the 18-month study period, 212 patients were enrolled. When the Airtraq was used as first-line airway device (n=106) vs. direct laryngoscopy (n=106), success rate was 47% vs. 99%, respectively (p<.001). Reasons for failed Airtraq intubation were related to the fiber-optic characteristic of this device (i.e., impaired sight due to blood and vomitus, n=11) or to assumed handling problems (i.e., cuff damage, tube misplacement, or inappropriate visualization of the glottis, n=24). In 54 of 56 patients where Airtraq intubation failed, direct laryngoscopy was successful on the first attempt; in the remaining two and in one additional case of failed direct laryngoscopy, the airway was finally secured employing the Fastrach laryngeal mask. There was no correlation between success rates and body mass index, age, indication for airway management, emergency medical service unit, or experience of the physicians. CONCLUSIONS: Based on these results, the use of the Airtraq laryngoscope as a primary airway device cannot be recommended in the prehospital setting without significant clinical experience obtained in the operation room. We conclude that the clinical learning process of the Airtraq laryngoscope is much longer than reported in the anesthesia literature.

Use of the Airtraq laryngoscope for emergency intubation in the prehospital setting: A randomized control trial
Crit Care Med. 2011 Mar;39(3):489-93

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Video laryngoscope successes and failures

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With a difficult airway, video laryngoscopes can get you out of a hole – or rather into one. However they’re not guaranteed for all eventualities; a large study of Glidescope use showed:

  • Primary intubation with the Glidescope was successful in 98% of 1,755 cases and rescued failed direct laryngoscopy in 94% of 239 cases.
  • Altered neck anatomy with presence of a surgical scar, radiation changes, or mass was the strongest predictor of Glidescope failure.

 

 

INTRODUCTION: The Glidescope video laryngoscope has been shown to be a useful tool to improve laryngeal view. However, its role in the daily routine of airway management remains poorly characterized.
METHODS: This investigation evaluated the use of the Glidescope at two academic medical centers. Electronic records from 71,570 intubations were reviewed, and 2,004 cases were identified where the Glidescope was used for airway management. We analyzed the success rate of Glidescope intubation in various intubation scenarios. In addition, the incidence and character of complications associated with Glidescope use were recorded. Predictors of Glidescope intubation failure were determined using a logistic regression analysis.
RESULTS: Overall success for Glidescope intubation was 97% (1,944 of 2,004). As a primary technique, success was 98% (1,712 of 1,755), whereas success in patients with predictors of difficult direct laryngoscopy was 96% (1,377 of 1,428). Success for Glidescope intubation after failed direct laryngoscopy was 94% (224 of 239). Complications were noticed in 1% (21 of 2,004) of patients and mostly involved minor soft tissue injuries, but major complications, such as dental, pharyngeal, tracheal, or laryngeal injury, occurred in 0.3% (6 of 2,004) of patients. The strongest predictor of Glidescope failure was altered neck anatomy with presence of a surgical scar, radiation changes, or mass.
CONCLUSION: These data demonstrate a high success rate of Glidescope intubation in both primary airway management and rescue-failed direct laryngoscopy. However, Glidescope intubation is not always successful and certain predictors of failure can be identified. Providers should maintain their competency with alternate methods of intubation, especially for patients with neck pathology.

Routine Clinical Practice Effectiveness of the Glidescope in Difficult Airway Management
Anesthesiology. 2011 Jan;114(1):34-41

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Anaesthesia's dirty laundry – let's all learn from it

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NAP4 is here! Is that good? Yes. Why? Because it’s the long awaited 4th National Audit Project of the Royal College of Anaesthetists and the Difficult Airway Society in the United Kingdom – a multi-phase national survey that was designed to answer the questions;

  • What types of airway device are used during anaesthesia and how often?
  • How often do major complications, leading to serious harm, occur in association with airway management in anaesthesia, in the intensive care units and in the emergency departments of the UK?
  • What is the nature of these events and what can we learn from them, in order to reduce their frequency and consequences?

The Audit identified 33 deaths and 46 cases of death or brain damage as a result of airway complications during anaesthesia, in ICU and the emergency department over a one year period in the four countries of the United Kingdom.

Some major findings include:

  • Poor planning contributed to poor airway outcomes – often a failure to plan for failure.
  • The project identified numerous cases where awake fibreoptic intubation (afoi) was indicated but was not used. A lack of suitable equipment was prevalent on ICU.
  • Problems arose when difficult intubation was managed by multiple repeat attempts at intubation.
  • Events were reported where supraglottic airway devices (SAD) were used inappropriately. Patients who were markedly obese, often managed by junior trainees, were prominent in the group of patients who sustained non-aspiration events. Numerous cases of aspiration occurred during use of a first generation SAD in patients who had multiple risk factors for aspiration and in several in whom the aspiration risk was so high that rapid sequence induction, should have been used.
  • The proportion of obese patients in case reports submitted to NAP4 was twice that in the general population
  • When rescue techniques were necessary in obese patient they failed more often than in the non-obese.

Here’s my favourite bit so far – in keeping with what the literature has already told us about this technique:

There was a high failure rate of emergency cannula cricothyroidotomy, approximately 60%. There were numerous mechanisms of failure and the root cause was not determined; equipment, training, insertion technique and ventilation technique all led to failure. In contrast a surgical technique for emergency surgical airway was almost universally successful. The technique of cannula cricothyroidotomy needs to be taught and performed to the highest standards to maximise the chances of success, but the possibility that it is intrinsically inferior to a surgical technique should also be considered. Anaesthetists should be trained to perform a surgical airway.

  • failure to correctly interpret a capnograph trace led to several oesophageal intubations going unrecognised in anaesthesia. A flat capnograph trace indicates lack of ventilation of the lungs: the tube is either not in the trachea or the airway is completely obstructed. Active efforts should be taken to positively exclude these diagnoses. This applies equally in cardiac arrest as CPR leads to an attenuated but visible expired carbon dioxide trace.
  • at least one in four major airway events reported to NAP4 was from ICU or the emergency department. The outcome of these events was more likely to lead to permanent harm or death than events in anaesthesia. Analysis of the cases identified gaps in care that included: poor identification of at-risk patients, poor or incomplete planning, inadequate provision of skilled staff and equipment to manage these events successfully, delayed recognition of events and failed rescue due to lack of or failure of interpretation of capnography. The project findings suggest avoidable deaths due to airway complications occur in ICU and the emergency department.

ICU

  • failure to use capnography in ventilated patients likely contributed to more than 70% of ICU related deaths. Increasing use of capnography on ICU is the single change with the greatest potential to prevent deaths such as those reported to NAP4.
  • Displaced tracheostomy, and to a lesser extent displaced tracheal tubes, were the greatest cause of major morbidity and mortality in ICU. Obese patients were at particular risk of such events and adverse outcome from them. All patients on ICU should have an emergency re-intubation plan.

 
ED

  • Most events in the emergency department were complications of rapid sequence induction. This was also an area of concern in ICU. RSI outside the operating theatre requires the same level of equipment and support as is needed during anaesthesia. This includes capnography and access for equipment needed to manage routine and difficult airway problems.

These are just snippets – there is much more in the report, and I’m still going through it.
The Executive Summary and all other Sections of NAP4 can be downloaded here from the Royal College of Anaesthetists
 

All Updates, ICU, Resus

Longer apnoea time with roc in the obese too

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Suxamethonium increases muscle oxygen consumption as a result of skeletal muscle fasciculation. In a comparison between sux and rocuronium in rapid sequence intubation, this resulted in faster desaturation in the sux group. A further study demonstrates a similar finding in obese patients.

BACKGROUND: Rapid sequence induction may be associated with hypoxemia. The purpose of this study was to investigate the possible difference in desaturation during rapid sequence induction in overweight patients using either succinylcholine or rocuronium.
METHODS: Sixty patients with a body mass index (BMI) between 25 and 30 kg/m², American Society of Anesthesiologists class I or II, undergoing general anesthesia were randomly divided into a succinylcholine group and a rocuronium group. After a 3-min preoxygenation, patients received rapid sequence induction of general anesthesia with midazolum-fentanyl-propofol and succinylcholine (1.5 mg/kg) or rocuronium (0.9 mg/kg). Ventilation was not initiated until oxygen saturation declined to 92%. We measured the times when oxygen saturation reached 98%, 96%, 94% and 92%. Safe Apnea Time was defined as the time from administration of neuromuscular blocking drugs to oxygen saturation fell to 92%. The recovery period was defined as the time from initiation of ventilation until oxygen saturation was 97%. Arterial blood gases were taken at baseline, after preoxygenation and at 92% oxygen saturation.
RESULTS: The mean Safe Apnea Time (95% CI) was 283 (257-309) s in succinylcholine vs. 329 (303-356) s in rocuronium (P=0.01). The mean recovery period (95% CI) was 43 (39-48) s in succinylcholine vs. 36 (33-38) s in rocuronium (P=0.002). Blood gas analysis showed no difference between the two groups.
CONCLUSIONS: Succinylcholine was associated with a significantly more rapid desaturation and longer recovery of oxygen saturation than rocuronium during rapid sequence induction in overweight patients.

Desaturation following rapid sequence induction using succinylcholine vs. rocuronium in overweight patients
Acta Anaesthesiol Scand. 2011 Feb;55(2):203-8

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African study on cricoid pressure

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The inventor of cricoid pressure. Possibly.

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

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Pre-hospital RSI and single use blades

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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.

A French doctor (not involved in the study)

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

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More on Rocuronium (and Sugammadex)

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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:

  1. Brief the team that rocuronium is to be used and that should an unanticipated difficult airway situation be encountered, then sugammadex will be used to reverse the effects of the rocuronium.
  2. Allocate the task of drawing up the sugammadex to a specific team member who has no additional role in the rapid sequence induction.
  3. Before induction, a calculation is made of the dose of sugammadex (16 mg/kg) that would be required and the volume of drug that should be drawn up.
  4. The instruction is given that should the anaesthetist not confirm intubation within 2 min, then the sugammadex is to be drawn up and handed to the anaesthetist for administration.


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:

  • Suxamethonium offers no real advantages over rocuronium for RSI in critical care – rocuronium at a dose of 1.2 mg/kg will provide similar intubating conditions to a good dose of sux9
  • Whatever you use, you need a rescue plan (supraglottic airway or transtracheal airway) for the CICV scenario
  • Sugammadex is a useful reversal agent in elective anaesthesia but is unlikely to be useful in a critical care scenario; however, if its use is anticipated it needs to be rehearsed as a standardised drill
  • Most of the literature on these agents pertains to well patients undergoing elective anaesthesia and we should be cautious about extrapolating results to the critical care setting
  • Finally, the urgency of a CICV can be reduced by CICVBCO – ‘can’t intubate, can’t ventilate, but CAN oxygenate’ – apnoeic diffusion oxygenation should be employed using pharyngeal or nasal oxygen10. Such a simple but underutilised technique can hugely improve the safety of RSI in critical care, and is described here.

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

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Neuromuscular blockade facilitates mask ventilation

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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