More evidence that the obsession with cervical collars is founded on dogma rather than science
Background All trauma patients with a cervical spinal column injury or with a mechanism of injury with the potential to cause cervical spinal injury should be immobilised until a spinal injury is excluded. Immobilisation of the entire patient with a rigid cervical collar, backboard, head blocks with tape or straps is recommended by the Advanced Trauma Life Support guidelines. However there is insufficient evidence to support these guidelines.
Objective To analyse the effects on the range of motion of the addition of a rigid collar to head blocks strapped on a backboard.
Method The active range of motion of the cervical spine was determined by computerised digital dual inclinometry, in 10 healthy volunteers with a rigid collar, head blocks strapped on a padded spine board and a combination of both. Maximal opening of the mouth with all types of immobiliser in place was also measured.
Results The addition of a rigid collar to head blocks strapped on a spine board did not result in extra immobilisation of the cervical spine. Opening of the mouth was significantly reduced in patients with a rigid collar.
Conclusion Based on this proof of principle study and other previous evidence of adverse effects of rigid collars, the addition of a rigid collar to head blocks is considered unnecessary and potentially dangerous. Therefore the use of this combination of cervical spine immobilisers must be reconsidered.
An excellent thorough review of emergency needle and surgical cricothyroidotomy – collectively described as ’emergency percutaneous airway’ – reveals a number of pearls.
The cricothyroid menbrane has an average height of 10 mm and a width of 11 mm
Transverse incision in the lower half of the cricothyroid membrane is recommended to avoid the cricothyroid arteries and the vocal cords
Regarding oxygenation / ventilation via a cricothyroid needle:
High pressure source ventilation via a needle (eg. by Sanders injector or Manujet) may cause laryngospasm, so a neuromuscular blocking agent should be considered
Barotrauma may result from an obstructed upper airway, so efforts should be made to maintain upper airway patency where possible (eg. with a supraglottic airway)
A device has been manufactured that provides suction-generated expiratory ventilation assistance (using oxygen flow and the Bernoulli principle) – the Ventrain
The Fourth National Audit Project reported a much lower success rate and described several complications of attempted re-oxygenation via a narrow-bore cricothyroidotomy
Where there is no kink-resistant cannula or suitable high-pressure source ventilation device readily available, it is probably safer to perform a wide-bore cannula puncture or surgical cricothyroidotomy.
Tend to be preferred by anaesthetists over the surgical and wide-bore cannula-over-trocar techniques
Seldinger technique in human cadavers and manikin studies by those well trained, inexperienced operators have low success rates and a long performance time
What about after?
High-pressure source ventilation may aid subsequent intubation by direct laryngoscopy as bubbles may be seen emerging from the glottis.
The Seldinger technique has been recommended to convert a narrow-bore cannula into a cuffed wide-bore cricothyroidotomy
While conversion of cricothyroidotomy to tracheostomy within 72 h has been advocated because of the increased risk of developing subglottic stenosis with prolonged intubation through the cricothyroid membrane, this risk may be much lower than previously believed
The risk of conversion, although less well examined, may also be appreciable
Which technique is best?
The recent NAP4 audit reported a success rate of only 37% for narrow-bore cannula-over-needle cricothyroidotomy, 57% for wide-bore cannula techniques and 100% for surgical cricothyroidotomy
Simulation studies show conflicting results about whether seldinger or surgical technique is faster.
Reported success rates of the different techniques (in simulations) also vary widely and range for surgical cricothyroidotomy from 55% to 100%, for wide-bore cannula-over-trocar from 30% to 100%, and for Seldinger technique from 60% to 100%.
The one area of some consensus is that conventional (low-pressure source) ventilation should not be used with a narrow-bore cannula; a high-pressure oxygen source and a secure pathway for the egress of gas are both mandatory to achieve adequate ventilation.
Complications may be related to technique:
Complications of narrow-bore cannula techniques are ventilation-related and include barotrauma, subcutaneous emphysema, pneumothorax, pneumomediastinum and circulatory arrest due to impaired venous return; Cannula obstruction due to kinking also occurs.
Seldinger technique may be complicated by kinking of the guidewire, which increases the risk of tube misplacement
Bleeding and laryngeal fracture may complicate the surgical method, and long-term complications include subglottic stenosis, scarring and voice changes.
This interesting study introduces a novel technique for guiding the inflation of tracheal tube cuffs to avoid excessive cuff pressures: listening with a stethoscope over the thyroid cartilage and inflating the cuff until breath sounds change from harsh to soft.
Tracheal tube cuffs are commonly inflated to pressures exceeding the recommended upper limit of 30 cmH2O. We evaluated whether a stethoscope-guided method of cuff inflation results in pressures within the recommended range. Patients were randomly assigned to receive one of two methods of cuff inflation. In the standard ‘just seal’ group, air was introduced into the tracheal cuff until the audible leak at the mouth disappeared. In the stethoscope-guided group, air was introduced into the cuff until a change from harsh to soft breath sounds occurred, whilst listening with a stethoscope bell placed over the thyroid cartilage. Twenty-five patients were recruited
to each group. The median (IQR [range]) cuff pressure in the ‘just seal’ group was 34 (28–40 [18–49]) cmH2O, and in the stethoscope-guided group was 20 (20–26 [16–28]) cmH2O,
p < 0.0001. The stethoscope-guided method of tracheal tube cuff inflation is a novel, simple technique that reliably results in acceptable tracheal cuff pressures.
Three hand-ventilation systems were used in a simulated adult resuscitation to determine the delivered volumes. The mean minute ventilation delivered by each of the three devices investigated was significantly different, with the paediatric (500-ml) self-inflating bag producing the result most consistent with the guideline.
There is a discrepancy between resuscitation teaching and witnessed clinical practice. Furthermore, deleterious outcomes are associated with hyperventilation. We therefore conducted a manikin-based study of a simulated cardiac arrest to evaluate the ability of three ventilating devices to provide guideline-consistent ventilation. Mean (SD) minute ventilation was reduced with the paediatric self-inflating bag (7.0 (3.2) l.min(-1) ) compared with the Mapleson C system (9.8 (3.5) l.min(-1) ) and adult self-inflating bag (9.7 (4.2) l.min(-1) ; p = 0.003). Tidal volume was also lower with the paediatric self-inflating bag (391 (52) ml) compared with the others (582 (87) ml and 625 (103) ml, respectively; p < 0.001), as was peak airway pressure (14.5 (5.2) cmH(2) O vs 20.7 (9.0) cmH(2) O and 30.3 (11.4) cmH(2) O, respectively; p < 0.001). Participants hyperventilated patients' lungs in simulated cardiac arrest with all three devices. The paediatric self-inflating bag delivered the most guideline-consistent ventilation. Its use in adult cardiopulmonary resuscitation may ensure delivery of more guideline-consistent ventilation in patients with tracheal intubation.
Comparison of the Mapleson C system and adult and paediatric self-inflating bags for delivering guideline-consistent ventilation during simulated adult cardiopulmonary resuscitation Anaesthesia. 2011 Jul;66(7):563-7
A nice idea – using a single adult self-inflating bag for the resuscitation of adult and paediatric patients, marked to identify compression points that deliver specific tidal volume ranges. Might be useful in situations where equipment needs to be minimised, such as military or pre-hospital settings.
AIM: To overcome limitations of inaccurate tidal volume (TV) delivery by conventional selfinflating paediatric and adult bags during paediatric and adolescent resuscitation, we designed a novel target volume marked bag (TVMB) with four compression points marked on an adult bag surface. The aim of this study was to evaluate the TVMB in delivering preset TV.
METHODS: Fifty-three subjects (28 doctors, 17 nurses, 8 paramedics) participated in this simulation trial. TVMB, paediatric bag and adult bag were connected to a gas flow analyser for measuring TV and peak inspiratory pressure (PIP). In a random cross-over setting, participants delivered 10 ventilations using the adult bag, paediatric bag or TVMB in each of four target volume ranges (100-200ml, 200-300ml, 300-400ml, 400-500ml). We compared TV and PIP for the adult bag, paediatric bag and TVMB in each subject.
RESULTS: Compared with the paediatric bag, TVMB showed higher rates of accurate TV delivery in the 200-300ml target volume range (87-90% versus 32-35%; p<0.05). Compared with the adult bag, TVMB showed higher rates of accurate TV delivery in all target volume ranges (75-90% versus 45-50%; p<0.05). The frequency of too high or low TV delivery was higher with the adult bag than TVMB (20-30% versus 0-5%; p<0.05). There was no significant difference in PIP between the paediatric bag and TVMB (within 5cm H(2)O; p<0.05).
CONCLUSIONS: TVMB could deliver accurate TV in various target volume ranges for paediatric and adolescent resuscitation.
Three quarters of attempts to place the FAST 1 sternal intraosseous device were successful…
Introduction: Access to the vascular system of the critically ill or injured adult patient is essential for resuscitation. Whether due to trauma or disease, vascular collapse may delay or preclude even experienced medical providers from obtaining standard intravenous (IV) access. Access to the highly vascular intramedullary space of long bones provides a direct link to central circulation. The sternum is a thin bone easily identified by external landmarks that contains well-vascularized marrow. The intraosseous (IO) route rapidly and reliably delivers fluids, blood products, and medications. Resuscitation fluids administered by IV or IO achieve similar transit times to central circulation. The FAST-1 Intraosseous Infusion System is the first FDA-approved mechanical sternal IO device. The objectives of this study were to: (1) determine the success rate of FAST-1 sternal IO device deployment in the prehospital setting; (2) compare the time of successful sternal IO device placement to published data regarding time to IV access; and (3) describe immediate complications of sternal IO use.
Methods: All paramedics in the City of Portsmouth, Virginia were trained to correctly deploy the FAST-1 sternal IO device during a mandatory education session with the study investigators. The study subjects were critically ill or injured adult patients in cardiac arrest treated by paramedics during a one-year period. When a patient was identified as meeting study criteria, the paramedic initiated standard protocols; the FAST-1 sternal IO was substituted for the peripheral IV to establish vascular access. Time to deployment was measured and successful placement was defined as insertion of the needle, with subsequent aspiration and fluid flow without infiltration.
Results: Over the one-year period, paramedics attempted 41 FAST-1 insertions in the pre-hospital setting. Thirty (73%) of these were placed successfully. The mean time to successful placement was 67 seconds for 28 attempts; three of the 31 insertions did not have times recorded by the paramedic. Paramedics listed the problems with FAST-1 insertion, including: (1) difficulty with adhesive after device placement (3 events); (2) failure of needles to retract and operator had to pull the device out of the skin (2 events); and (3) slow flow (1 event). Emergency department physicians noted two events of minor bleeding around the site of device placement.
Conclusion: This is the first study to prospectively evaluate the prehospital use of the FAST-1 sternal IO as a first-line device to obtain vascular access in the critically ill or injured patient. The FAST-1 sternal IO device can be a valuable tool in the paramedic arsenal for the treatment of the critically ill or injured patient. The device may be of particular interest to specialty disaster teams that deploy in austere environments.
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
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.
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.