Tag Archives: airway

Acute Med, All Updates, ICU, PHARM, Resus

咽反射是沒用的 – just as we thought

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The painful dogma of “GCS ≤8 = intubate” is nicely challenged by the A&E Academic Unit at Prince of Wales Hospital in Hong Kong, who provide some further evidence that patients with a higher GCS may have absent airway protective reflexes, and patients with a lower GCS may have intact reflexes.


AIM: To describe the relationship of gag and cough reflexes to Glasgow coma score (GCS) in Chinese adults requiring critical care.

METHOD: Prospective observational study of adult patients requiring treatment in the trauma or resuscitation rooms of the Emergency Department, Prince of Wales Hospital, Hong Kong. A long cotton bud to stimulate the posterior pharyngeal wall (gag reflex) and a soft tracheal suction catheter were introduced through the mouth to stimulate the laryngopharynx and elicit the cough reflex. Reflexes were classified as normal, attenuated or absent.

RESULTS: A total of 208 patients were recruited. Reduced gag and cough reflexes were found to be significantly related to reduced GCS (p=0.014 and 0.002, respectively). Of 33 patients with a GCS≤8, 12 (36.4%) had normal gag reflexes and 8 (24.2%) had normal cough reflexes. 23/62 (37.1%) patients with a GCS of 9-14 had absent gag reflexes, and 27 (43.5%) had absent cough reflexes. In patients with a normal GCS, 22.1% (25/113) had absent gag reflexes and 25.7% (29) had absent cough reflexes.

CONCLUSIONS: Our study has shown that in a Chinese population with a wide range of critical illness (but little trauma or intoxication), reduced GCS is significantly related to gag and cough reflexes. However, a considerable proportion of patients with a GCS≤8 have intact airway reflexes and may be capable of maintaining their own airway, whilst many patients with a GCS>8 have impaired airway reflexes and may be at risk of aspiration. This has important implications for airway management decisions.

What is the relationship between the Glasgow coma scale and airway protective reflexes in the Chinese population?
Resuscitation. 2011 Jul 23. [Epub ahead of print]
Related post: Do all comatose patients need intubation?

All Updates, ICU, Resus, Ultrasound

Ultrasound to detect difficult laryngoscopy

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A pilot study suggests sonographic measurements of neck soft tissue thickness may predict difficult laryngoscopy. Laryngoscopy was difficult in patients with increased thickness of the anterior neck soft tissue at the level of the hyoid bone and thyrohyoid membrane. The authors suggest that anterior neck soft tissue thickness cutoff value of 2.8 cm at the thyrohyoid membrane level can potentially be used to detect difficult laryngoscopy, but that this would require further validation since in this pilot study there were only six subjects in the difficult laryngoscopy group.


Objectives:  Prediction of difficult laryngoscopy in emergency care settings is challenging. The preintubation clinical screening tests may not be applied in a large number of emergency intubations due to the patient’s clinical condition. The objectives of this study were 1) to determine the utility of sonographic measurements of thickness of the tongue, anterior neck soft tissue at the level of the hyoid bone, and thyrohyoid membrane in distinguishing difficult and easy laryngoscopies and 2) to examine the association between sonographic measurements (thickness of tongue and anterior neck soft tissue) and difficult airway clinical screening tests (modified Mallampati score, thyromental distance, and interincisor gap).

Methods:  This was a prospective observational study at an academic medical center. Adult patients undergoing endotracheal intubation for an elective surgical procedure were included. The investigators involved in data collection were blinded to each other’s assessments. Demographic variables were collected preoperatively. The clinical screening tests to predict a difficult airway were performed. The ultrasound (US) measurements of tongue and anterior neck soft tissue were obtained. The laryngoscopic view was graded using Cormack and Lehane classification by anesthesia providers on the day of surgery. To allow for comparisons between difficult airway and easy airway groups, a two-sided Student’s t-test and Fisher’s exact test were employed as appropriate. Spearman’s rank correlation coefficients were used to examine the association between screening tests and sonographic measurements.

Results:  The mean (±standard deviation [SD]) age of 51 eligible patients (32 female, 19 male) was 53.1 (±13.2) years. Six of the 51 patients (12%, 95% confidence interval [CI] = 3% to 20%) were classified as having difficult laryngoscopy by anesthesia providers. The distribution of laryngoscopy grades for all subjects was 63, 25, 4, and 8% for grades 1, 2, 3, and 4, respectively. In this study, 83% of subjects with difficult airways were males. No other significant differences were noted in the demographic variables and difficult airway clinical screening tests between the two groups. The sonographic measurements of anterior neck soft tissue were greater in the difficult laryngoscopy group compared to the easy laryngoscopy group at the level of the hyoid bone (1.69, 95% CI = 1.19 to 2.19 vs. 1.37, 95% CI = 1.27 to 1.46) and thyrohyoid membrane (3.47, 95% CI = 2.88 to 4.07 vs. 2.37, 95% CI = 2.29 to 2.44). No significant correlation was found between sonographic measurements and clinical screening tests.

Conclusions:  This pilot study demonstrated that sonographic measurements of anterior neck soft tissue thickness at the level of hyoid bone and thyrohyoid membrane can be used to distinguish difficult and easy laryngoscopies. Clinical screening tests did not correlate with US measurements, and US was able to detect difficult laryngoscopy, indicating the limitations of the conventional screening tests for predicting difficult laryngoscopy.

Pilot Study to Determine the Utility of Point-of-care Ultrasound in the Assessment of Difficult Laryngoscopy
Acad Emerg Med. 2011 Jul;18(7):754-8

All Updates, PHARM, Resus, Trauma

Effect of physician specialty on pre-hospital intubation success

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Researchers from the London Helicopter Emergency Medical Service describe the success of pre-hospital laryngoscopy according to the grade and specialty of the HEMS physician…

There is conflicting evidence concerning the role and safety of prehospital intubation, and which providers should deliver it. Success rates for physician-performed rapid sequence induction are reported to be 97-100%, with limited evidence of improved survival in some patient groups. However, there is also evidence that prehospital intubation and ventilation can do harm. Prospective data were recorded on the success of intubation, the quality of the laryngeal view obtained and the number of attempts at intubation. These data were then analysed by the grade of intubating doctor and whether the intubating doctor had a background in anaesthesia or emergency medicine. All groups had a similar success rate after two attempts at intubation. Doctors with a background in anaesthesia and consultant emergency physicians had a significantly better first-pass intubation rate than emergency medicine trainees. The quality of laryngeal view was significantly better in doctors with an anaesthetics background.

Success in physician prehospital rapid sequence intubation: what is the effect of base speciality and length of anaesthetic training?
Emerg Med J. 2011 Mar;28(3):225-9

All Updates, ICU, Resus

Crike rate 1 in 500 in Scottish ED

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A review of over 2500 intubation attempts in the emergency department1, (of which 1671 were rapid sequence intubation attempts) revealed five cricothyroidotomies, giving a crike rate of 0.2% which is much lower than in some other ED based registries. In four patients, predictors of difficult airway were identified before the endotracheal intubation attempt, and formal preparation for rescue surgical airway was performed. Three of the surgical airways were performed by emergency medicine trainees, one by an emergency medicine specialist and one by an ear, nose and throat specialist. There was a 100% success rate for placement of all surgical airways on the first attempt.

Four surgical airways were done in trauma patients: laryngeal fracture, facial burns, Le Fort II facial fracture and penetrating neck injury.
This study is of interest to UK emergency physicians who may be interested in Edinburgh Royal Infirmary’s collaborative approach to emergency airway management by the Departments of Emergency Medicine, Anaesthesia and Critical Care.
It is not possible to tell from this paper whether there were patients in whom surgical airway was indicated but not performed, and therefore in my view the ostensibly ‘good’ low rate of 0.2% should be viewed with interest rather than awe. Having said that, this figure is more in keeping with my own experience and expectation from UK/Australasian practice; it has been highlighted in the UK EM literature before2, including by myself3, that in our patient group good training and supervision should result in lower surgical airway rates than the ~1% often quoted.


OBJECTIVES: To determine the frequency of and primary indication for surgical airway during emergency department intubation.

METHODS: Prospectively collected data from all intubations performed in the emergency department from January 1999 to July 2007 were analysed to ascertain the frequency of surgical airway access. Original data were collected on a structured proforma, entered into a regional database and analysed. Patient records were then reviewed to determine the primary indication for a surgical airway.

RESULTS: Emergency department intubation was undertaken in 2524 patients. Of these, only five patients (0.2%) required a surgical airway. The most common indication for a surgical airway was trauma in four of the five patients. Two patients had attempted rapid sequence induction before surgical airway. Two patients had gaseous inductions and one patient received no drugs. In all five patients, surgical airway was performed secondary to failed endotracheal intubation attempt(s) and was never the primary technique used.

CONCLUSION: In our emergency department, surgical airway is an uncommon procedure. The rate of 0.2% is significantly lower than rates quoted in other studies. The most common indication for surgical airway was severe facial or neck trauma. Our emergency department has a joint protocol for emergency intubation agreed by the Departments of Emergency Medicine, Anaesthesia and Critical Care at the Edinburgh Royal Infirmary. We believe that the low surgical airway rate is secondary to this collaborative approach. The identified low rate of emergency department surgical airway has implications for training and maintenance of skills for emergency medicine trainees and physicians.

1. Surgical airway in emergency department intubation
Eur J Emerg Med. 2011 Jun;18(3):168-71
2. Rapid sequence induction in the emergency department: a strategy for failure.
Emerg Med J. 2002 Mar;19(2):109-13
3. RSI by non-anaesthetists in the UK – lower incidence of cricothyrotomy than in the US
EMJ e-letters 2002; 3 April

All Updates, ICU, PHARM, Resus, Trauma

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

All Updates, PHARM

American airway management in the field

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I often wonder why my US colleagues are so vehemently opposed to out-of-hospital tracheal intubation. This paper provides a clue. I would love it if any EMS providers out there could comment, as I find these results staggering.
The authors comment that the data set “contains data on over 4.3 million EMS events from 16 states (Alabama, Colorado, Florida, Hawaii, Iowa, Maine, Minnesota, Missouri, North Carolina, North Dakota, Nebraska, New Hampshire, New Jersey, New Mexico, Nevada, and Oklahoma) for the one-year period January 1, 2008–December 31, 2008. These states were the first to participate in the NEMSIS project. There are no estimates of the numbers of EMS agencies or EMS responses that are not included in NEMSIS. Hawaii, New Jersey, New Mexico and Oklahoma provided only partial data for the study period because of their implementation of NEMSIS during 2008.”

OBJECTIVE: Prior studies describe airway management by single EMS agencies, regions or states. We sought to characterize out-of-hospital airway management interventions, outcomes and complications across the United States.
 
METHODS: Using the 2008 National Emergency Medical Services Information System (NEMSIS) Public-Release Data Set containing data from 16 states, we identified patients receiving advanced airway management, including endotracheal intubation (ETI), alternate airways (Combitube, Laryngeal Mask Airway (LMA), King LT, Esophageal-Obturator Airway (EOA)), and cricothyroidotomy (needle and open). We examined airway management success and complications in the full cohort and in key subsets (cardiac arrest, non-arrest medical, non-arrest injury, children <10 and 10-19 years, rapid-sequence intubation (RSI), population setting and US census region). We analyzed the data using descriptive statistics.
RESULTS: Among 4,383,768 EMS activations, there were 10,356 ETI, 2246 alternate airways, and 88 cricothyroidotomies. ETI success rates were: overall 6482/8418 (77.0%; 95% CI: 76.1-77.9%), cardiac arrest 3494/4482 (78.0%), non-arrest medical 616/846 (72.8%), non-arrest injury 417/505 (82.6%), children <10 years 295/397 (74.3%), children 10-19 years 228/289 (78.9%), adult 5829/7552 (77.2%), and rapid-sequence intubation 289/355 (81.4%). ETI success was success was lowest in the South US census region. Alternate airway success was 1564/1794 (87.2%). Major complications included: bleeding 84 (7.0 per 1000 interventions), vomiting 80 (6.7 per 1000) and esophageal intubation 12 (1.0 per 1000).
CONCLUSIONS: In this study characterizing out-of-hospital airway management across the United States, we observed low out-of-hospital ETI success rates. These data may guide national efforts to improve the quality of out-of-hospital airway management.

Out-of-hospital airway management in the United States
Resuscitation. 2011 Apr;82(4):378-85

All Updates, ICU, Kids, PHARM, Resus, Trauma

Intubation checklist

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Perhaps you’ve read the blog post and heard the podcast about the excellent NAP4 airway audit…..now you can start putting the learning points into action with the intubation checklist, developed by the regional trainee-led collaborative ‘RTIC Severn’. Thanks to Dr Tim Bowles for the link:

I’ve used an RSI checklist for both in-and-out of hospital intubations for the last seven years. The beauty of this one is the potential for it to become a standard within and between hospitals, so wherever you work the team will be on the same page when preparing for intubation.
Further details are at http://saferintubation.com

All Updates, ICU, Resus

NAP 4 Podcast

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Check out EMCrit.org for our Podcast interview with Professor Jonathan Benger, the Emergency Physician who contributed to the design, execution, and analysis of the important NAP 4 national airway audit, which has important learning points for all of us involved in pre-hospital, emergency, or ICU airway management.

EMCrit Podcast
2016 Update
An important follow up study showing the effect of the NAP 4 Audit:
A national survey of the impact of NAP4 on airway management practice in United Kingdom hospitals: closing the safety gap in anaesthesia, intensive care and the emergency department
Br. J. Anaesth. (2016) 117 (2): 182-190.

All Updates, ICU, Kids, Resus

Colorimetric CO2 detectors and newborns

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Colorimetric CO2 detectors may fail to indicate successful tracheal tube placement in adults in certain circumstances, such as low cardiac output states, and waveform capnography is considered the gold standard. We now have data that demonstrate their inadequacy for neonatal intubation. Ideally, waveform devices should be used by all professionals who intubate patients – from paramedics to neonatologists.

AIM: Clinical assessment and end-tidal CO(2) (ETCO(2)) detectors are routinely used to verify endotracheal tube (ETT) placement. However, ETCO(2) detectors may mislead clinicians by failing to identify correct placement under a variety of conditions. A flow sensor measures gas flow in and out of an ETT. We reviewed video recordings of neonatal resuscitations to compare a colorimetric CO(2) detector (Pedi-Cap®) with flow sensor recordings for assessing ETT placement.
METHODS: We reviewed recordings of infants <32 weeks gestation born between February 2007 and January 2010. Airway pressures and gas flow were recorded with a respiratory function monitor. Video recording were used (i) to identify infants who were intubated in the delivery room and (ii) to observe colour change of the ETCO(2) detector. Flow sensor recordings were used to confirm whether the tube was in the trachea or not. RESULTS: Of the 210 infants recorded, 44 infants were intubated in the delivery room. Data from 77 intubation attempts were analysed. In 35 intubations of 20 infants both a PediCap® and flow sensor were available for analysis. In 21 (60%) intubations, both methods correctly identified successful ETT placement and in 3 (9%) both indicated the ETT was not in the trachea. In the remaining 11 (31%) intubations the PediCap® failed to change colour despite the flow wave indicating correct ETT placement.
CONCLUSION: Colorimetric CO(2) detectors may mislead clinicians intubating very preterm infants in the delivery room. They may fail to change colour in spite of correct tube placement in up to one third of the cases.

Assessment of flow waves and colorimetric CO2 detector for endotracheal tube placement during neonatal resuscitation
Resuscitation. 2011 Mar;82(3):307-12

All Updates, ICU, Resus

Disposable flexible intubating scope

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There is now a single use flexible intubating device that compares favourably with conventional fibreoptic devices. It does not have fibreoptic cables, but rather has a small camera at its tip illuminated by an LED. The image is transmitted via a cable in the device to a reusable screen. Dr Cook’s team in Bath, England have an extensive track record of evaluating new airway devices, and they report their assessment of this gadget in a manikin-based study. I think this may extend the airway management options to departments or teams for whom the cost and maintenance of conventional fibreoptic equipment is prohibitive.

We compared the Ambu aScope™ with a conventional fibrescope in two simulated settings. First, 22 volunteers performed paired oral and nasal fibreoptic intubations in three different manikins: the Laerdal Airway Trainer, Bill 1 and the Airsim (a total of 264 intubations). Second, 21 volunteers intubated the Airway Trainer manikin via three supraglottic airways: classic and intubating laryngeal mask airways and i-gel (a total of 66 intubations). Performance of the aScope was good with few failures and infrequent problems. In the first study, choice of fibrescope had an impact on the number of user-reported problems (p=0.004), and user-assessed ratings of ease of endoscopy (p<0.001) and overall usefulness (p<0.001), but not on time to intubate (p=0.19), or ease of railroading (p=0.72). The manikin chosen and route of endoscopy had more consistent effects on performance: best performance was via the nasal route in the Airway Trainer manikin. In the second study, the choice of fibrescope did not significantly affect any performance outcome (p=0.3), but there was a significant difference in the speed of intubation between the devices (p=0.02) with the i-gel the fastest intubation conduit (mean (SD) intubation time i-gel 18.5(6.8)s, intubating laryngeal mask airway = 24.1(11.2)s, classic laryngeal mask airway = 31.4(32.5)s, p=0.02). We conclude that the aScope performs well in simulated fibreoptic intubation and (if adapted for untimed use) would be a useful training tool for both simulated fibreoptic intubation and conduit-assisted intubation. The choice of manikin and conduit are also important in the success of such training. This manikin study does not predict performance in humans and a clinical study is required.

Evaluation of a single-use intubating videoscope (Ambu aScopeTM) in three airway training manikins for oral intubation, nasal intubation and intubation via three supraglottic airway devices
Anaesthesia. 2011 Apr;66(4):293-9