Back up Airway Devices; the Good, the bad, and the Ugly.

[Dustdevil]

PA is in the process of writing statewide ALS protocols.

Why?

Sounds like some power-hungry bureaucrats are trying to justify their inflated salaraies.

[Medic26]

The statewide protocols have been designed so that there is consistent care across the state, as of now you have each region writing their own. The pitfall to them is that they will have to be approved by each region and may be modified by your local/regional medical directors. For our region, the statewide protocol will be a step backward in some area's and a step foreword in others. Our medical director has already verbally approved several upgrades for us including nasal medication administration, the King airway and a standing pain management protocol........he just likes to use what someone else has already written so we have to wait for the hard copy to be approved at the state level. All in all I think this will be a good thing.

[Dustdevil]

All in all I think this will be a good thing.

Yeah... everybody in the Northeast seems to think that. Sure glad I don't live there. :?

Sucks if you're living in a system that is already good.

I wonder why it is that no other medical profession on earth has seen the necessity to institute "protocols" like this?

I guess the people running EMS are just so much smarter than every other profession's leaders. :roll:

[Ace844]

(Positive Pressure Ventilation With the Laryngeal Mask Airway in the Operating Room and Prehospital: A Practical Review

[Review Article)

Matioc, Adrian A. MD; Wells, Jeffrey A. MD

From the Department of Anesthesiology (A.A.M.), Section of Pulmonary/Critical Care Medicine (J.A.W.), University of Wisconsin Hospital and Clinics, Medical School, Flight Physician, Department of Medicine, Section of Emergency Medicine, Med Flight, University of Wisconsin Hospital and Clinics, Madison, Wisconsin.

Submitted for publication January 3, 2005.

Accepted for publication July 13, 2005.

Address for Reprints: Adrian A. Matioc, MD, VA Medical Center, Department of Anesthesiology, 2500 Overlook Terrace, Madison, WI 53705; email: aamatioc@facstaff.wisc.edu]

Airway management is the core skill for prehospital health care providers. Orotracheal intubation of the critically ill patient is used with variable success, with or without drug-assistance by the prehospital Emergency Medicine System. Failed orotracheal intubation requires specifically defined alternatives. In the United States two supraglottic airway devices are in use in the prehospital setting: the Combitube (ETC; Kendall-Sheridan, Argyle, N.Y.) and the Laryngeal Mask Airway (LMA; LMA North America, San Diego, Calif.). The LMA is used extensively in the operating room since the early 1990s and recently its use has been recommended as an alternative airway in the prehospital setting. However, implementation of the operating room experience without considering the specifics of the prehospital environment (patient variables, providers experience and training, devices available, and time restraints) will be contra productive. We discuss the emergence of the LMA as a prehospital airway device focusing on the contrast between hospital and prehospital use and the optimal training of the prehospital rescuer.

The LMA was developed by Dr. Brain, a British anesthesiologist 1 and was introduced in the operating room (OR) in the United Kingdom (UK) and Australia in the late 1980s and in the US in 1992.

The LMA proved in the OR to be a lifesaving device in the “unexpected difficult airway” in elective and emergent cases. In 1993 the LMA was mentioned and in 1996 and 2003 included in the American Society of Anesthesiologists (ASA) Difficult Airway Algorithm.2 Benumof defined the role of the LMA in the difficult airway and the “cannot ventilate, cannot intubate” (CV-CI) situation.3 The LMA has since been included in the “Guidelines 2000 for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care International Consensus on Science” expanding the scope of the LMA to the emergent prehospital environment.4 The LMA is used in the field since the early 1990s in Australia,5 Canada,6 Europe,7 and Japan 8 and more recently in the US.9–11

The LMA consists of an airway tube connected to an elliptical cuff that is inserted in the hypopharynx. The standard insertion technique uses the (dominant hand) index finger that is placed at the cuff-tube junction. The index finger will guide the deflated cuff with the aperture faced forward along the same path followed by the food bolus: hard palate, soft palate, posterior oropharynx, and hypopharynx. In the final position the tip of the LMA is wedged in the esophagus and the cuff inflated around the glottis (Fig. 1). The standard insertion technique is not intuitive and Brain considers this “the most difficult part of the procedure to communicate to the new user.”1

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[Email Jumpstart To Image] Fig. 1. The laryngeal mask in situ.

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POSITIVE PRESSURE VENTILATION WITH THE LARYNGEAL MASK

The hallmark of the prehospital airway management (in contrast to the OR) is the cumulative and changing factors that continuously challenge the prehospital rescuer. In the prehospital the LMA is used for positive pressure ventilation (PPV) in a “full stomach” patient in critical condition with an uncleared cervical spine in immediate need for oxygenation and ventilation after failed bag valve mask ventilation (BVM) and endotracheal intubation (ETI) attempts.

The concept behind the use of the LMA in the prehospital and in the OR in the cannot intubate/cannot ventilate (CI-CV) setting is identical: when BVM and endotracheal intubation (ETI) fail the benefit of the LMA use (oxygenation, ventilation) outweighs its potential risk (aspiration).12

There is a vast literature pertinent to the OR use of the LMA.13 Implementing the LMA in the prehospital practice, demands a careful scrutiny of the current LMA knowledge and analysis of its relevance for the prehospital practice.

The LMA is considered “easy to teach to the novice.” This is the conclusion reached by multiple studies; recently reviewed by Pollack.14 However, in these studies regardless of the complexity of the training the instructor was an anesthesiologist. The unsupervised “inexperienced” LMA users were highly motivated and rigorously trained volunteers.15–17 Training of paramedics that successfully used the LMA in the field was comprehensive, including an anesthesiologist as instructor and OR time.

The trainees who did not spend time in the OR, although technically skilled to use the LMA on a mannequin, expressed anxiety in using the device on a patient.18 Kaye et al. addressed the importance of the instructor in teaching critical skills.19 Instructors who may have little or no clinical experience with the device should not perform LMA training for the prehospital rescuer.

The LMA is considered “an easy to use and forgiving device.” This concept stems from the primary use of the LMA in the OR with spontaneous ventilation in elective cases. The LMA is “forgiving” in spontaneously breathing patients as it may generate a patent airway even when used suboptimally (folded, misplaced, or overinflated).

The anesthesiology literature still debates the safety of the LMA with PPV in electively paralyzed patients.20 The LMA cuff generates the seal on the soft periglottic tissues. The lower seal pressure developed might cause difficulties in patients that require high airway inflation pressure (for increased airway resistance or low pulmonary compliance). Positive pressure ventilation with the LMA in the OR appears to be adequate if airway resistance and pulmonary compliance are normal.21 Gastric insufflation occurred in only 2.1% of patients at inflation pressures of 15 cm H2O but increased to 35.4% at 30 cm H2O.22 Latorre et al. recommend reducing the risk of gastric insufflation by keeping the peak inspiratory pressure below 20 cm H2O.23 Regurgitation and aspiration with the LMA are more commonly associated in the OR with periods of light general anesthesia and patient in Trendelenburg position.

The risks attributed in the OR to PPV with the LMA in paralyzed patients can be extrapolated to the prehospital setting. The trauma patient ventilated with an LMA may need high pulmonary inflation pressures, may be in Trendelenburg position, and/or may have a gag reflex (“light general anesthesia”). In this context the patient is at increased risk for gastric inflation, regurgitation, and aspiration.

Asai 24 and Brain,1 caution to the widespread misuse of the LMA in the anesthesiology community emphasizing the correct insertion technique, the adequate depth of anesthesia during insertion and maintenance and monitoring the airway pressure during ventilation. Successful PPV is linked to skill and experience.25

The need to improve the seal and protection from regurgitation/aspiration led to the development of the ProSeal LMA–PSLMA (LMA North America, San Diego, Calif.)26 and since 2000 to its use in the OR. The PSLMA has a modified cuff to improve the seal (5 cm H2O higher then the LMA) and a drainage tube to provide access to the gastrointestinal tract (Fig. 2). The LMA is easier and quicker to insert with the index finger technique then the PSLMA. The PSLMA was used in difficult airway situations in the OR but there are no reports of its use in the prehospital setting.

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[Email Jumpstart To Image] Fig. 2. The ProSeal laryngeal mask with the drainage tube for gastrointestinal access.

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Brimacombe and Berry determined the incidence of pulmonary aspiration in the OR associated with the LMA to be 2/10,000.27 This number is comparable to that for outpatient anesthesia with facemask and ETI. The authors cautioned: “meticulous patient selection an adherence to the guidelines for its use should reduce the incidence of aspiration even further.” “Patient selection” in the trauma patient in the CV-CI situation is not a practical goal; “adherence to guidelines” specifically developed should be the priority!

There is no consensus in the anesthesiology literature about the interaction of cricoid pressure (CP) and LMA insertion.28–31 In the prehospital setting the CP is released in different circumstances: personnel shortage, to improve BVM ventilation or during a difficult intubation attempt. Aspiration is described in the field after forceful and inadequate BVM ventilation, multiple laryngoscopies, or esophageal intubation. The early and correct use of the LMA (“first line airway device”) may have a role in reducing regurgitation in the prehospital setting.32 There are no clinical reports describing aspiration/regurgitation as a limiting factor in the prehospital use of the LMA.

The LMA protects the airway from above the cuff contamination as demonstrated by John et al.33; this is significant for trauma patients with bleeding facial injuries that need airway management.

Cervical spine protection is an essential duty of the rescuer. Application of a rigid cervical collar in patients with impaired consciousness may induce upper airway obstruction 34 and makes airway manipulation, BVM ventilation and ETI difficult.35

Expert users consider insertion of the LMA with the head in the neutral position “slightly more difficult” than performed in the sniffing position.36 Another study concluded that in paralyzed patients with the head in neutral position and manual in line stabilization (MILS) applied insertion took significantly longer and suboptimal positioning of the LMA was significantly higher.37 This may be further complicated by simultaneous application of CP.38

Keller and Brimacombe studied the vertebral motion and the pressures developed on the cervical spine by the use of different airway devices. They concluded that in a patient with a posteriorly destabilized cervical three segment the safest method for airway management is the fiberoptic nasotracheal intubation and the LMA may be preferable to the Combitube.39

There are no reports on the motion and the pressure developed on the cervical spine by an inexperienced user during LMA insertion. Poor insertion technique with the LMA directed straight into the mouth, perpendicularly to the cervical spine, may induce further cervical spine movement potentially increasing the risk of neurologic injury. The incorrectly inserted device will exert pressure at the C2–C3 level, which is involved in 27% of all fractures and 41% of all dislocations in blunt cervical spine injuries.40

Application of the rigid cervical collar may interact with the LMA in situ by compressing the periglottic structures. This can improve the LMA seal and ventilation but may also dislodge the device, generate airway obstruction and/or compromise the seal.11

In critical circumstances optimal use of the LMA is paramount: prehospital training programs should target basic skills and their specific application in the prehospital environment (neutral head position, CP, MILS, cervical collar, “full stomach,” PPV, aspiration, transport).

CLINICAL SKILLS FOR THE PREHOSPITAL USE OF THE LMA

Similar to the first laryngoscopy,41 the first LMA insertion attempt should be optimized.

Is the Correct LMA Size Selected?

The LMA Classic is available in six sizes. The manufacturer recommends two size selection criteria: weight based (for adults patients: size 3, 30 to 50 kg, size 4, 50–70 kg, size 5, 70–100 kg, and recently size 6 for >100 kg) and gender based (size 4 for female and size 5 for male adults). The manual also recommends that clinical judgment should be used in selecting the size.

Is the LMA Ready to Use?

The device is prepared (deflation and lubrication of the dorsal surface with a water soluble lubricant), stored, and used in an uncontrollable and unpredictable environment. The LMA, water soluble lubricant and a syringe should be packaged together. The disposable LMA-Unique (sizes #3, #4, and #5) (LMA North America, San Diego, Calif.) offers this advantage.

Is the Patient Ready to Accept the LMA?

Insertion of the LMA during inadequate level of anesthesia is a common mistake. A patient who is not “deep enough” (gagging, coughing …) will fight the LMA insertion and discourage the rescuer from inserting the index finger deep into the mouth resulting in misplacement of the device. A misplaced LMA is more likely to be dislodged or to trigger reflexes (laryngospasm, glottic closure, vomiting, or hiccups).42

In the OR the loss of motor response to the “jaw thrust” is considered more reliable to assess adequate “depth” than the loss of verbal contact with the patient.43 Unwanted effects of the jaw thrust may include cervical spine mobilization and stimulation of the patient.

Optimal Insertion of the LMA

The rescuer will insert the LMA in variable positions: standing (emergency room), kneeling (scene, ambulance), sitting (helicopter), and from the patient’s side (difficult extrication). Experienced anesthesiologists need at least 2 cm distance between the upper and the lower incisors to insert the LMA.44 The kneeling position is suboptimal for the ETT placement but advantageous for the LMA insertion. The standard index finger technique is used when standing or kneeling at the patient’s head. This technique is superior to any other insertion techniques.45 The thumb technique is useful when the victim is trapped (motor vehicle crash) or difficult to reach from above the head. The rescuer standing by the side of the patient will use the thumb of the dominant hand that substitutes the index finger to guide the LMA along the palato-pharyngeal path. The insertion success rate of the thumb technique is lower than the index finger technique.46

The most common error made during the early learning phase with the standard technique is the insertion of the LMA straight into the mouth without using the hard palate as a slide and with the index finger not inserted deep enough into the mouth, misplacing the LMA. Other reasons for failure are: choice of wrong LMA size, incomplete cuff deflation, inability to get the mask past the teeth, inability to advance the cuff past the base of the tongue, insufficient air, or overinflation of the LMA cuff.47 An automated voice advisory manikin may correct these predictable mistakes.48

Neutral head position, CP, and MILS can complicate the LMA insertion. Insertion of the LMA should be attempted with the anterior half of the cervical collar removed and MILS applied. Brimacombe recommends that LMA insertion with CP applied should be attempted only if the oxygen saturation (SpO2) is >95%. If insertion fails, CP should be released for the second attempt. If the SpO2 is <95% initial insertion should be with CP released as ventilation/oxygenation is more important than preventing aspiration.13

Optimal Cuff Inflation

Inflate the cuff with two-thirds of the maximum volume recommended (marked on the LMA tube), then, add 3 to 5 mL of air, as needed up to the maximum volume recommended. A rigid over inflated cuff will loose its ability to mold on the soft periglottic tissues: over inflation will not compensate for malposition but will further compromise the seal and the use of PPV. The manufacturer recommends the use of a pressure gauge for optimal cuff inflation. All current literature pertinent to supraglottic airway devices (SGD) standardizes cuff inflation pressure to 60 cm H2O.

LMA Ventilation

Pharyngeal and esophageal leaks are expected with airway pressure over 20 cm H2O. Overzealous ventilation with no airway pressure monitoring can lead to a “misperceived” leak in an otherwise correctly placed LMA. Chest movement with small TV may be difficult to evaluate in a dressed victim, with chest trauma or strapped chest. Auscultation (chest, neck, and epigastrum) with small TV in a noisy environment may be deceiving. The use of the inflatable bulb (esophageal detector device) with the LMA is discouraged.49

In the OR the most specific test to detect LMA misplacement (defined fiberoptically) was the ability to generate airway pressure of 20 cm H2O without a leak whereas, the ability to ventilate manually (movement of the chest, condensation of expired gases, adequacy of expired gas volume and the feel of the bag) had the highest overall accuracy.

Is the Patient Ready for Transport?

Tape the LMA firmly in the midline to the upper jaw without bending the tube toward the forehead; keep the LMA tube in a neutral position (bended toward the chin) being vigilant not to dislodge the device during transport or manipulation of the resuscitation bag. A bite block will increase the device’s stability.50 Asai et al. considers that although CP applied after correct placement of the LMA significantly decreases the incidence of gastric insufflation, it also decreases the adequacy of ventilation.51

Ventilation should be reassessed after the application of the anterior cervical collar. If monitored, the airway pressure should be kept under 20 cm H2O.

Regurgitation in the LMA Tube

Brain considers the LMA cuff protective by filling the pharyngeal space otherwise filled with aspirate and should not be removed; also the LMA tube represents a path of minimal resistance, an alternative to the trachea.52

In the event of regurgitation/aspiration disconnect the breathing tube and allow regurgitated material to drain, and then gently ventilate using small tidal volumes (TV) with 100% Fio2. Place the patient with cervical spine precautions in Trendelenburg position. Sedate and/or paralyze the patient that is “too light.” Oxygenation should be maintained during the incident.

Suction the LMA tube. There is no predictable continuum between the LMA tube and the glottic opening.53 A suction catheter will most likely not penetrate the trachea (for the same reason rescue medications administered through the LMA will not reach consistently the trachea). If the LMA fails (reduced chest wall movement, deteriorating O2SAT and ETCO2, increased airway pressure) other airway management options should be considered.

CONCLUSION: EDUCATION AND TRAINING

In this report we discuss the emergence of the LMA as a prehospital airway device focusing on the contrast between the OR and prehospital training and practice.

In the OR the LMA skills are acquired and improved along an immediate (15 uses), a short term (75 uses), and a long-term (750 uses) learning curve.54–56 Experienced anesthesiologists will reach a >99% successful usage rate after three attempts.57 In the OR a first time insertion rate of less than 90% is considered suboptimal.56 In the prehospital environment the rate of successful LMA use is lower (65–88%).14 Good results are correlated with experience, skill, and complex training.

The OR is a controlled environment: help and technology (airway pressure, tidal volume, and ETCO2 monitors) will reduce the trainee’s stress level.58 The prehospital LMA curriculum needs specific clinical/technical endpoints reflecting field realities to build confidence for early and optimal use of the device in the critically ill.59,60 Too many times the rescuer will not abandon an unsuccessful but “familiar” technique (BVM, ETI) because he or she is unfamiliar with the alternative option. Training should provide lectures, video, mannequin, and OR time specifically designed for the prehospital user. LMA insertion should simulate field conditions (e.g. LMA insertion with the manikin on the floor with a second rescuer maintaining MILS, CP).61

Baskett called for a “national standard” for the prehospital LMA training.62 In the UK the “Intravent Course” is widely used as the out of OR LMA training program.

Two SGD Are Currently Used in the Prehospital: the Combitube (Kendall-Sheridan, Argyle, N.Y.) and the LMA. There is a plethora of potential new prehospital SGD: the ProSeal LMA and the Fastrach LMA (LMA North America, San Diego, Calif.), the Laryngeal Tube and Laryngeal Tube Suction (King Systems, Noblesville, Ind.), the Easy Tube (Rusch, Kernen, Germany), the Soft Seal LM (Portex Ltd., Hythe, Kent, UK), Ambu LM (Ambu A/S, Ballerup, Denmark). Regardless of their current limitations and imperfections the SGD herald a new era in the airway management.

The 2003 ASA Guidelines for the management of the difficult airway encourages early use of a SGD as a rescue airway: in emergent situation oxygenation and ventilation take precedent over intubation. In their recent review Dunham et al. concludes that there is a need to develop (drug assisted) tracheal intubation strategies in the EMS systems and implement plans to manage the failed orotracheal intubation.63 Development of specific guidelines for appropriate training and use of the SGD in the prehospital setting will optimize airway management and may improve outcome.

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[paramedicmike]

I can't speak for anyone else, but the proposed revision of PA's protocols suck. It will, in fact, be a step up for some and a step back for others. What's worse, as was noted, each region will have to decide to adopt them so the idea of COMMONWEALTH (PA's not a state ) wide protocols is really a non issue. And if one particular region decides they don't want it then that pretty much kills the idea of consistent care across the Commonwealth. (And several regions reportedly have already said they won't adopt them.)

Dust, be glad you don't live in the NE. (Except for Maine. From people I've spoken with Maine seems to be ok.)

But back to the issue at hand.

My full time job uses the LMA as a back up (yes, in PA...but it's with a flight service). I used it in the field for the first time recently on what turned out to be a difficult airway. It was easily placed and worked well. In fact, it saved this guy from coding on me! :shock: (He was not a fun patient.)

My biggest problem with the LMA is that the tips can fold back on insertion. I've had this happen a couple of times in the OR. I'm not quite sure if it's something I'm doing or not. I've worked with a couple CRNAs and anesthesiologists on this problem and they've all said it's not my technique. Maybe, as Spock noted, I'm just a slow learner and need to drop a few more to work the bugs out.

The two ground services for whom I work use the combitube. I've never had to use a combitube in the field. I've played with it on mannequins but that's it. So I can't speak with any kind of authority on how well it actually works.

For what it's worth, hope this helps.

-be safe.

[Ace844]

"Mike,"

Have you tried doing the insertion with the baloon partially inflated? I had a similar issue and found this helped allieveate the problem.

Hope this Helps,

ACE844

[paramedicmike]

I've heard that a partially inflated cuff will help. I didn't think to try it the last time. But it'll definitely be something to keep in mind the next time around.

I heard somewhere, too, that the manufacturers don't recommend insertion like that. But I haven't seen it in print yet so I don't know for sure.

But if it works and I don't flip the tip around I'm happy. Thanks for the reinforcement of that tip!!! Nice to know it's worked for others out there.

-be safe.

[Ace844]

I've heard that a partially inflated cuff will help. I didn't think to try it the last time. But it'll definitely be something to keep in mind the next time around.

I heard somewhere, too, that the manufacturers don't recommend insertion like that. But I haven't seen it in print yet so I don't know for sure.

But if it works and I don't flip the tip around I'm happy. Thanks for the reinforcement of that tip!!! Nice to know it's worked for others out there.

-be safe.

Anytime ,

[AZCEP]

It can make it more challenging to get into position, but it will make the turn much better.

I think my new favorite back up device is the King-LT. It is much cheaper than the Combi-tube, doesn't have the latex cuffs, and is placed almost as easily as an OPA. The full kit from narrescue.com is $55. For just the tube, it is only $15. Then you just have to find a 60 mL syringe to fill the cuffs.

My favorite feature of this device is the ramp in the distal port that allows you to use a bougie through it, and replace it with an ETT. Pure genius, I tell you. Practicing on manikins, I've had EMT partners place the King, then ventilate for a bit, then place an ETT later. Haven't had any opportunities with actual patients yet, but we are prepared for the first one.

[n3qtrtme]

Just thought you might like to know about the new version of the King LT-D that's being released in September. It's the King LTS-D and includes a second lumen for suctioning. You can tube through it with a 6.0 ETT or use an ET Introducer to place the ETT. Details, pictures and specs are available at www.kingsystems.com.

Concerning the cost, Tri-anim has them for about $35 in the EMS Kit.