Boone County Fire District EMS Education-EMT Course Fundamentals Unit-Airway Control and Ventilation Resources
Screencast For lab---sniffing position
● In order for cells to function properly, the circulatory system must deliver oxygen and glucose to the cells. We have discussed the circulatory system in a previous lesson. In that discussion, we saw how the pulmonary circulation interfaces with the inhaled air in the alveoli. All of that circulation must be reasonably intact and functioning in order for oxygen to be delivered from the lungs to the systemic circulation.
● The process of getting gases (O2 and CO2 principally) to interface with the blood is called Oxygenation and is handled in another lesson.
● Right now, we will focus on the process of getting air from the outside into the alveoli where Oxygenation happens. That process of moving fresh air in and exhausting stale air is called Ventilation.
● Those three processes---Circulation, Ventilation and Oxygenation (“CVO”) form the core of our patient assessment because of their critical roles in maintaining life.
● Ventilation requires an intact pathway for air to get from the outside to the alveoli as well as adequate air movement through those pathways. Both are key. Neither is sufficient without the other.
○ Airway Control involves keeping the upper airway pathway open and clear of obstructions.
○ Ventilation involves movement of air through the upper and lower airways to the alveoli.
● Upper airway anatomy of interest and how to control the airway: ○ Tongue---the most common airway obstruction. This is a large and heavy
muscle that can be pulled by gravity in the supine patient to the back (posterior) of the upper airway (pharynx) and create a partial obstruction (snoring sounds) or a complete obstruction (no sounds). Fortunately, the jaw bone (mandible) can act as a handle for the tongue and when the jaw is thrusted forward (anteriorly) using a jaw thrust maneuver, the tongue can be displaced off the posterior pharynx and the airway opened. We will also practice a head tilt-chin lift airway maneuver in Lab in case you are ever alone with a patient and need that technique. The jaw thrust remains our primary manual airway maneuver.
○ Noisy airways are not open airways---usually due to upper airway obstruction---usually due to the tongue being pulled by gravity. Placing the patient in the “recovery” (drainage, coma) position may use gravity to an advantage to displace the tongue anteriorly. This position is of no help when the patient needs positive pressure ventilation or chest compressions. So, we need other tools and techniques.
○ Oropharyngeal airways (oral airways or OPAs) are hard plastic devices designed to hold the tongue off the posterior pharyngeal wall. These must be sized and placed appropriately and patients with a gag reflex still intact won’t tolerate them.
Boone County Fire District EMS Education-EMT Course Fundamentals Unit-Airway Control and Ventilation Resources
○ Nasopharyngeal airways (nasal airways, nasal trumpets or NPAs) are soft rubber tubes that provide a pathway for air from the nose past the posterior pharynx. Patients with intact gag reflexes can tolerate these airways.
○ OPAs and NPAs can be used together---two NPAs works fine also except you might want to leave a nostril open for medication administration unless you really need both NPAs to keep the airway open.
○ We will practice the use of jaw thrusts, OPAs and NPAs in a Lab Session. ○ OPA-NPA older screencast--short and good to watch (not the best audio).
● Other upper airway obstructions: ○ Swelling from infected tissue or inflamed tissue following a burn or due to an
allergic reaction can create an upper airway obstruction. This obstruction can be partial (air movement still heard) or total (no air movement heard). The high-pitched squeaking or squealing sound made when the upper airway is obstructed is called stridor and can be heard loudest over the Adam’s Apple with a stethoscope (louder there than over the lungs). At the EMT level, there is really not much that can be done for this cause of obstruction other than assisting an allergic reaction patient with his / her prescribed epi-pen (talked about later in the Course).
○ Food / vomit (emesis) / blood in the mouth and pharynx can be inhaled (aspirated) into the lungs and create a lower airway obstruction. Once lodged in the lungs, removal is not possible in the field. Therefore, we must focus on removing these materials from the mouth / pharynx rapidly. Positioning the patient on their side (lateral recumbent) is a relatively quick technique while suction devices are being prepared and while they are in use. This positioning doesn’t work for patients who are requiring chest compressions for CPR. Otherwise, rolling the patient quickly is key. Manual suction devices (such as the V-Vac) use hand powered squeezes to remove liquid matter and some smaller “chunks”. Mechanical suction devices (battery powered) are also just as useful. We will practice the use of these in a Lab Session. Check out those two video links showing how the two devices are just about equal in terms of speed of suctioning. Note on the manual device how we squeeze and “let it eat”--hold the squeeze rather than squeezing rapidly and repeatedly.
○ Patients who are “choking” on objects (food or otherwise) are best managed by having them cough forcefully to expel the object. Once the patient cannot cough, an abdominal thrust is used in the conscious but not supine patient. Once the patient is supine, a chest thrust is used. We will practice these techniques in a Lab Session.
● Advanced airways are used to provide a tube as a pathway for air exchange. Some advanced airways called supraglottic airways or SGA can be used by EMTs. The very best advanced airway, an endotracheal tube (ET tube or ETT) can only be placed by Paramedics in the field. Paramedics can also utilize a surgical airway to cut into the patient’s larynx at the Adam’s Apple area for the most severe cases. We will focus on
Boone County Fire District EMS Education-EMT Course Fundamentals Unit-Airway Control and Ventilation Resources
SGAs for this EMT Course. Supraglottic refers to “above” (supra) the “glottis” (laryngeal inlet to the trachea)
○ SGAs allow an airway to be placed without directly visualizing the laryngeal inlet (at the vocal cords---entrance to the trachea). These are called “blind insertion” because no direct visualization of the larynx is needed.
○ The SGA that we will teach for our EMT Course is the King LT(S)D. This advanced airway has a large cuff that seals the pharynx and a smaller cuff that seals the esophagus. Air is ventilated through the airway tube to a port that is positioned directly over the laryngeal inlet (opening to the trachea). As long as both cuffs are sealing off effectively, the air is forced into the trachea. Insertion is simple and fast. The King comes in various sizes to fit various patient heights. In a Lab Session, we will work on the sizing, testing, insertion and adjusting of the King including how to handle the three possible situations following insertion:
■ You see good chest rise and the patient is easy to ventilate. (proper placement and proper cuff seal---all good)
■ You see no chest rise and the patient is easy to ventilate.(add air to the cuff to improve your seal)
■ You see no chest rise and the patient is hard to ventilate. (pull the tube back a little bit---the port is not over the laryngeal inlet)
○ Without trying to jump ahead---we should point out that the primary advantage to a SGA in cardiac arrest is that it allows you to perform continuous chest compressions instead of pausing to give a ventilation. For this reason, early use of the SGA in cardiac arrest is key to high-quality CPR---and only EMTs or Paramedics can legally insert the SGA in Missouri.
○ Screencast from the Paramedic Program’s Airway & Breathing Course ● Once the Airway is controlled, Ventilation can be the focus.
○ Assessing Ventilation is based on three criteria---any one of which can cause inadequate ventilation and require intervention:
■ Rate of breathing ● Breathing too slowly (usually 6 or less per minute) simply doesn’t
move enough air in an out to meet the needs of life in most cases. ● Breathing too rapidly (usually 30 or more per minute) may lead to
inadequate air movement due to the shallow nature of those breaths. Patients can be breathing rapidly and deeply (hyperventilation) but usually rapid breathing equals shallow breathing.
■ Effort of breathing ● Patients use their diaphragm as the primary muscle of breathing.
Patients can use accessory muscles of breathing (neck, belly, muscles between the ribs called intercostals). The use of accessory muscles indicates an increase effort of breathing that may require intervention.
Boone County Fire District EMS Education-EMT Course Fundamentals Unit-Airway Control and Ventilation Resources
● Normal breathing is really with little effort. The only effort that is expended is to inhale---exhalation is passive (not much work needed) in normal cases. When patients are working to exhale as well as inhale, that indicates an increase effort of breathing that may require intervention. If you notice a patient’s breathing---be concerned that it is not normal.
■ Depth of breathing ● Normal breathing depth is NOT maximal breathing depth. Normal
is less than maximum depth and really is not all that obvious. ● Shallow breathing Depth is also not all that noticeable if the
breathing Rate is allow slow. “Low and Slow” is bad and usually indicates the need for intervention.
○ Managing Ventilation is based on providing positive pressure ventilation to either supplement a breathing patients ineffective breaths or replacing their lack of breathing. Humans are negative pressure breathers by design---that is normal. We “suck” in air by creating a small vacuum inside the chest. When positive pressure breathing is required, this is NOT normal for the patient and some bad side effects may happen (a side effect is something we did not intend but are not surprised that it happened):
■ Gastric distention---air blown into a patient’s mouth may go into their lungs via the trachea but the pathway to their stomach via their esophagus is a lot lower pressure and therefore easier for the air to take. Distended (swollen) stomachs full of air tend to release and vomiting is the result.
■ Decreased blood pressure---the increase in pressure inside the chest from positive pressure ventilations makes it harder for blood to return to the heart from the systemic circulation. Decreased amount of blood returning to the heart (preload) causes the heart to struggle to fill and therefore it will be pumping out less (cardiac output). This lowers BP in most cases.
■ Screencast on positive pressure ventilation (older version--audio issues) ○ So...in summary..we prefer for patient’s to maintain their own airway and to
breathe on their own. If their airways need control, we should control them using the least invasive means necessary to do the job. If their ventilation needs assistance (due to a problem with Rate, Effort or Depth), we must use a positive pressure ventilation method until they can breathe on their own effectively. There are side effects to positive pressure ventilation and we should remember them.
○ How to deliver positive pressure breathing: ■ Unless / until you have a SGA in place, you will need a mask sealed over
the patient’s face. Getting the mask to seal is best done in conjunction with a good jaw thrust by using the “two thumbs down” method. You want both your thumbs pointing to the patient’s feet and on top of the mask.
Boone County Fire District EMS Education-EMT Course Fundamentals Unit-Airway Control and Ventilation Resources
This allows you to use the big muscles of your hand to squeeze the mask to the face while you lift the jaw. We will practice this in a Lab Session.
■ To deliver the breaths, you will either need to blow air from your mouth into the mask (for pocket mask ventilation) or use a bag-valve-mask (BVM) device to blow air into the patient.
● The bag-valve-mask is a TWO PERSON TOOL. The pocket mask is a one-person tool. When you have two persons to assign to the ventilation, use the BVM. When you do not have two persons to assign to the ventilation, use the pocket mask (PM).
● The BVM allows for easy use of supplemental oxygen for your patient as well. You can hook oxygen to some PMs and you can always just put the oxygen tubing under the PM but that makes a good seal very difficult.
■ Regardless of the tools you are using, the RATE OF VENTILATIONS is the same and must NOT be too fast. One breath every six seconds is plenty fast for an adult. Slightly more often for pediatric patient is okay---not more often than once every three seconds though (unless it is a newborn).
■ Regardless of the tools you are using, the DEPTH OF VENTILATIONS is the same and must NOT be too deep---just get normal chest rise. Many adult patients only require ⅓ to ½ the volume of the adult BVM. In fact, some services use the Pediatric BVM for adults to avoid delivering too much volume.
■ Regardless of the tools you are using, the PRESSURE OF VENTILATIONS is the same and must NOT be too forceful. High force / high pressure breaths end up in the stomach almost every time. Only use just enough pressure to get normal chest rise.
■ We will practice ventilation in a Lab Session. ■ Short video on “Two Thumbs Down” bag-mask ventilation.
Boone County Fire District EMS Education-EMT Course Fundamentals Unit-Airway Control and Ventilation Resources
● Proper mask sizing schematic
Optional stuff: Article on Difficult Mask Ventilation in PDF is attached at the end of this document. Smart Bag flyer on PDF is also included at the end of this document. Links to Screencasts below (slides included at the end of this document) from Paramedic Program’s Airway & Breathing Course x 4--covers Basic Airway Control: Sniffing Position Jaw Thrust-Mask Seal OPA-NPA Bag-Mask Ventilation
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G E N E R A L Tutorial 321
Key Points
• Incidence of difficult mask ventilation (MV) is approximately 1.4% and for impossible MV is approximately 0.15%
• It is important to assess patients for difficult MV as well as difficult intubation
• MMMMASK and OBESE are two mnemonics to help remember the risk factors for difficult MV
• Complications are wide-ranging, from trauma to eyes, nose or mouth to hypoxic brain injury and myocardial ischaemia
• When writing your anaesthetic chart it is important to document the ease of MV
• Management of unexpected difficult or impossible MV may benefit from regular airway practice drills or simulation
!DIFFICULT MASK VENTILATION Dr Jonathan Holland Anaesthetics Registrar, Royal Victoria Hospital, Northern Ireland, UK Dr Will Donaldson Consultant Anaesthetist, Antrim Hospital, Northern Ireland, UK Edited by Dr Luke Baitch and Dr Maytinee Lilaonitkul Correspondence to [email protected]
INTRODUCTION Mask ventilation (MV) is an integral skill for all anaesthetists. It forms the starting point of the majority of general anaesthetics and more importantly, it is an essential fall-back technique for maintaining oxygenation during a failed or difficult intubation. Despite its importance, less attention is devoted to MV in research papers and textbooks, with a larger focus on difficult or failed intubation. All anaesthetists require the skill to mask ventilate but more importantly they require the knowledge of how to adjust their management options when faced with a difficult or impossible MV scenario. This tutorial will provide an overview of the definition, incidence, predictors and management of difficult MV. There are some clinical situations when MV is not desirable, such as immediately post trans-sphenoidal surgery, but discussion of these is not within the scope of this tutorial. Definition of difficult mask ventilation Herein lies a central problem with research on difficult MV - over the years there have been various definitions of what constitutes difficult MV. It is an extremely subjective topic because what constitutes difficulty for an anaesthetic trainee beginning their career may be
8th OCT 2015
QUESTIONS Before continuing, try to answer the following questions. The answers can be found at the end of the article, together with an explanation. Please answer True or False: 1. Risk factors for difficult mask ventilation include:
a. A beard b. History of snoring c. BMI > 26kg/m2 d. History of alcohol excess e. Female gender
2. Possible complications of difficult mask ventilation include: a. Hypoxia b. Brachial plexus injury c. Aspiration d. Eye trauma e. Dislocated jaw
3. A patient has been given a long acting muscle relaxant, is impossible to mask ventilate and oxygen saturations have fallen to 88%. Appropriate next steps may include: a. Deepening anaesthesia b. Attempting to wake the patient up c. Attempting laryngoscopy d. Insertion of supraglottic airway device (SAD) e. Performing a surgical airway !
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vastly different from an anaesthetic consultant with 25 years’ experience. The American Society of Anesthesiologists (ASA) defined difficult MV as a situation in which: “It is not possible for the anesthesiologist to provide adequate ventilation because of one or more of the following problems: inadequate mask seal, excessive gas leak, or excessive resistance to the ingress or egress of gas.”1
The ASA then goes on to list signs of inadequate ventilation: absent or inadequate chest movement, absent or inadequate breath sounds, auscultatory signs of severe obstruction, cyanosis, gastric air entry or dilatation, decreasing or inadequate oxygen saturation, absent or inadequate exhaled carbon dioxide, absent or inadequate spirometric measures of exhaled gas flow, and haemodynamic changes. This is a very comprehensive definition but in some ways it remains vague and dependent on the operator’s judgment. Other papers have used similar definitions but have specified further criteria. Langeron et al. in 2000 specified inability to maintain saturations above 92%, using the oxygen flush more than twice, requiring 2 operators or a change of operator as indicators for difficult mask ventilation.2 Yildiz et al. in 2005 defined the difficulty depending on the airway manoeuvres used.3 Kheterpal et al. in 2006 defined difficult MV as inadequate MV, or MV requiring 2 operators.4 In each of these definitions the terms used can be interpreted differently, highlighting the difficulty in finding a universal definition. Given that achieving a universal definition is difficult, a way of communicating what worked for a patient would obviously be of benefit. As with many conditions in medicine, MV can be considered as a spectrum with one end being easy MV and the other being impossible MV.5 A definition to represent the various stages of difficulty to allow easier communication between clinicians was described by Han et al.6 It is a grading system 0-4 similar to the Cormack-Lehane grading of views at laryngoscopy, and is shown in Figure 1.
Figure 1: Table showing MV classification and description scale6
Incidence of difficult mask ventilation There has been a range of incidence reported due to lack of consensus in definition; the quoted range is wide at 0.08% to 15%. The most robust data show the incidence of difficult MV is approximately 1.4%,4 and impossible MV is approximately 0.15%.7 Factors affecting mask ventilation Anaesthetic factors Factors that have been shown to affect MV are the experience of the clinician and the use of equipment. The skill of MV is achieved through training and maintained through regular practice. This helps to address common issues such as patient position, airway manoeuvres and sizing of equipment. The use of incorrectly sized oropharyngeal or nasopharyngeal airways are unlikely to improve MV and may cause trauma and bleeding. Furthermore, MV may be difficult due to an improperly sized mask being used or faults with the anaesthetic machine or breathing circuit. Some aspects of general anaesthesia itself are thought to play a role. High dose opioids, inadequate depth of anaesthesia and inadequate muscle relaxation may all lead to increased muscle rigidity, reduced chest wall compliance and difficult MV. The chest wall rigidity associated with high dose opioids is not seen in patients with a tracheostomy. This leads to the suggestion that the resistance to MV is actually due to vocal cord closure, which resolves on administration of a muscle relaxant.8 These factors have led to debate about the timing of administration of muscle relaxant and whether to check if it is possible to mask ventilate the patient prior to administration. Muscle relaxants can make MV easier, by eliminating rigidity and laryngospasm, or more difficult, by causing loss of tone and upper airway collapse. The 4th National Audit Project by the Royal College of Anaesthetists and Difficult Airway Society (DAS) found that in some cases, light anaesthesia and a reluctance to administer muscle relaxants may have caused patient harm.9 The project made the following recommendations:
• “Where facemask or laryngeal mask anaesthesia is complicated by failed ventilation and increasing hypoxia the anaesthetist should consider early administration of further anaesthetic agent and or a muscle relaxant to exclude and treat laryngospasm.”
• “No anaesthetist should allow airway obstruction and hypoxia to develop to the stage where an emergency surgical airway is necessary without having administered a muscle relaxant.”
Classification Description Grade 0 Ventilation by mask not attempted Grade 1 Ventilated by mask Grade 2 Ventilated by mask with oral airway or other adjunct Grade 3 Difficult MV (inadequate, unstable, or 2 person technique) Grade 4 Unable to mask ventilate
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Patient factors Being able to anticipate difficult MV can help anaesthetists formulate an airway management plan that is safe for the patient. A simple and reassuring way of assessing the patient is to check their previous anaesthetic chart for any documented difficulties. This highlights the importance of good record keeping and also demonstrates how a reproducible grading system for mask ventilation can play a vital role in standardising communication between clinicians. Patient-specific factors can be the main cause for difficult mask ventilation; these are wide-ranging and can be categorised as shown in Figure 2.
Enlarged soft tissues Abnormal anatomy • Large tongue/epiglottis • Tonsillar hyperplasia • Airway oedema
• Edentulous • Beard • Upper or lower airway tumours • Extrinsic compression of airway • Foreign bodies • Pneumothorax • Bronchopleural fistula • Chest wall deformity • Previous neck irradiation
Physiological reactions • Laryngospasm • Bronchospasm
Figure 2: Patient factors associated with difficult mask ventilation
Other important factors include obesity, increasing age, male gender, Mallampati grading, ability for mandibular protrusion and history of obstructive sleep apnoea. Various BMI values have been used in research papers with one as low as 26kg/m2 being a statistically significant predictor of difficult MV.2 A high neck circumference (>40cm), which is associated with obesity, also increases the probability of difficult MV.10 Increasing age is another risk factor and this is likely due to the loss of elasticity in tissues and presence of lung disease. The mandibular protrusion test gives the assessor an indication of the ability to perform an adequate jaw thrust, and is important in patients at risk of upper airway collapse. Furthermore, it is also a good predictor of difficult intubation. The authors suggest a simple mnemonic to help remember these predictors: MMMMASK. Alternatively, Langeron et al. identified 5 criteria that were independent risk factors (OBESE) for difficult MV.2 Both mnemonics are summarised below.
MMMMASK OBESE M M M M A S K
Male gender Mask seal which is affected by beard or being edentulous Mallampati grade 3 or 4 Mandibular protrusion Age Snoring and obstructive sleep apnoea Kilograms (weight)
OBESE
Obese (BMI>26kg/m2) Bearded Edentulous Snoring Elderly (>55 years)
Figure 3: Two mnemonics helpful for remembering patient factors that are associated with difficult mask ventilation
With respect to impossible mask ventilation, Kheterpal et al. reviewed over 50,000 anaesthetics with an incidence of 0.15% and showed the following independent predictors: neck radiation, male sex, sleep apnoea, Mallampati 3-4, and the presence of a beard.7 Neck radiation was the most significant factor in predicting impossible MV and importantly, it is also a significant risk factor for difficult intubation. Careful consideration of airway plans for patients with previous neck radiation is required as surgical access may also be difficult MANAGEMENT AND COMPLICATIONS Management The management of difficult MV can be split into two scenarios: expected and unexpected. With expected difficult MV, simple measures can be taken such as shaving of beards, weight loss and keeping dentures in situ to improve the seal and removing them immediately prior to intubation. Some anaesthetists find it beneficial to slick down beards with jelly to improve the seal, however optimal management is to remove the beard with patient cooperation. As with all cases an airway plan should be formed and discussed with the anaesthetic assistant to allow for preparation of necessary equipment. Optimal preoxygenation is vitally important with the aim of providing an increased apnoeic time to allow more time for airway management before the patient’s oxygen saturations decline. Proper positioning of the patient helps to improve the apnoeic time by decreasing dependent atelectasis. In obese patients the ear should be at the same level as the sternal notch and so there may be a need to ramp the patient (figure 4). The ramped position helps to improve both ventilation and laryngoscopy view by aligning the oral, pharyngeal and laryngeal axes.
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Figure 4: A comparison between supine and ramped position in an obese patient. In a supine position (left), the ear is below the level of the sternal notch. In a ramped position (right), the ear is level with the sternal notch and the face is parallel with the ceiling.
Patel and Nouraei describe an alternate method of maintaining patient oxygenation using Transnasal Humidified Rapid-Insufflation Ventilatory Exchange (THRIVE).11 Continuous high-flow humidified oxygen was delivered transnasally pre- and post-induction of anaesthesia before a definitive airway was secured. This method of apnoeic oxygenation shows promise, however, in their case series they routinely checked that mask ventilation was possible before proceeding. THRIVE only works if the airway remains patent, which is the key to successful MV, so if it is possible to use THRIVE then it should be possible to mask ventilate. In cases where there are signs that suggest difficult MV and a potentially difficult intubation, awake fibreoptic intubation may be the correct choice. If difficult MV is predicted but an easy intubation anticipated, consideration may be given to rapid sequence induction. The benefit of this approach is quicker onset of neuromuscular blockade to facilitate earlier intubation without the need for MV. The risks associated with this are multiple and should be considered on a case-by-case basis. The main risks include desaturation within the time of onset of muscle relaxation and failure to intubate. In elective cases the back-up plan for these risks would be to insert a SAD to provide ventilation but in emergency non-fasted cases, this risks aspiration. Consideration should be given to awake fibreoptic intubation in these patients. The preoperative visit should include discussion of the options and risks with the patient. When MV is unexpectedly difficult the management becomes a dynamic process. There is no agreed adult algorithm but the Association of Paediatric Anaesthetists of Great Britain and Ireland along with the DAS have produced an algorithm for difficult MV in children aged 1-8 years.12 There is a proposed algorithm by El-Orbany and Woehlck detailing the management steps in difficult MV.5 Although major anaesthetic groups have yet to adopt this, it represents a sensible approach to the problem. The first steps in management are: optimising patient position and the use of airway adjuncts such as oropharyngeal and nasopharyngeal airways, the application of continuous positive airway pressure, checking the depth of anaesthesia, muscle relaxation and reducing cricoid pressure. If difficulty remains, i.e. the saturations are dropping or there is a lack of end-tidal carbon dioxide then there should be a call for help to allow a 2-person (or 4-hand) technique and/or change of operator and request for the difficult airway trolley. If this does not improve the situation and the saturations are now <90% the situation should be considered as an impossible MV scenario. If impossible MV develops, consideration should be given to waking the patient up, however this is not always a feasible option. If a neuromuscular blocking drug has been administered it may be appropriate to attempt intubation at this point or, in the case of rocuronium, to consider reversal with sugammadex. If unable to intubate then 2 attempts at insertion of a SAD would be appropriate if not already attempted. If a neuromuscular blocker has not been given then insertion of a SAD is an alternative. With a SAD in situ, consideration should be given to using it as a conduit to facilitate intubation. If the oxygen saturations are still dropping this is now a Can’t Intubate Can’t Ventilate (CICV) scenario and requires rescue techniques in the form of either a cannula cricothyroidotomy or surgical cricothyroidotomy. Figure 5 outlines the steps described above. Chrimes and Fritz describe the Vortex approach as a method to organise the management of this complex and evolving situation.13 This looks at achieving oxygenation via a facemask, SAD or endotracheal tube with a maximum of 3 attempts at each. Importantly, they can occur in any order after each has been optimised, and if oxygenation fails with these non-surgical airway techniques, then the next step is an emergency surgical airway. It would be reasonable to suggest that at least one attempt should be made by the most experienced available clinician. This will have been a stressful situation for the whole team and it will be of benefit to have a team debrief to discuss the events, outcome and raise any concerns for future training. Simulator training is becoming more and more frequent in training in anaesthesia and this type of scenario should be considered. Accurate documentation of the difficulties (airway adjunct, two-person technique, administration of neuromuscular blocking drugs), together with an explanation of what occurred to the patient, should follow such events.
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Figure 5: Flowchart for management of unexpected difficult MV
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Complications of difficult mask ventilation Difficult MV can cause numerous complications with the main concern being failure to oxygenate the patient causing death, hypoxic brain injury or myocardial ischaemia. Other complications include injuries to the eyes, nose and mouth. Eye injuries can occur due to direct trauma from the mask or fingers; dry gases leaking from the mask can themselves cause harm. Nasal airway adjuncts can cause false passages and bleeding which may further compromise the airway. Patients may develop pressure injury due to excessive use of force with the mask against the nose. The mouth and oropharynx contain many structures that may be injured during difficult MV; these include teeth, lips, soft palate, uvula and nerves. Lack of lubrication and excessive use of force for insertion of airway adjuncts can increase the risk of this type of trauma. With increasing difficulty in mask ventilation there is a tendency to increase the inflation pressure via the adjustable pressure-limiting (APL) valve on the anaesthetic machine. This can lead to a vicious cycle: if the airway is not patent, air will be directed into the stomach increasing intra-gastric pressure. This in turn leads to raised diaphragms and a decrease in lung compliance, which leads to more difficult MV. To avoid causing gastric inflation the APL valve should be kept to the minimum requirement and below 20cmH2O. This is specifically addressed in the paediatric guidelines which suggest the insertion of a nasogastric tube if gastric distension is present.12 Furthermore, if the airway is patent and being over-ventilated with high pressures, the increased intra-thoracic pressure can compromise venous return and lead to hypotension and decreased coronary perfusion. Difficult mask ventilation and difficult intubation This represents the worst-case scenario for most anaesthetists and has led to guidelines being developed for how to manage the CICV scenario. The risk factors for difficult intubation and difficult mask ventilation do have some overlap, for obvious reasons. The incidence of this difficult combination was found by Kheterpal et al. to be approximately 0.4%, with difficulty defined as grade 3 or 4 MV and a grade 3 or 4 view at laryngoscopy.14 This likely represents an underestimation given that anticipated difficult airways may have received an awake fibreoptic intubation. Other study by Kheterpal et al. looking at impossible MV found that 19 of the 77 (25%) impossible-to-ventilate patients (out of 50,000 cases) were also difficult to intubate; importantly, 15 of these patients were successfully intubated using various asleep techniques, only 3 were woken up (2 for awake fibreoptic intubation, 1 for awake surgical tracheostomy), and only one required an emergency surgical airway.7 ANSWERS TO QUESTIONS
1. a. True. A beard can cause difficulty in achieving an adequate seal when attempting MV and if concerned, the patient should be advised to shave it off. b. True. A history of snoring can indicate upper airway closure when relaxed and may be due to enlarged soft tissues. c. True. A BMI of 26kg/m2 or more is associated difficult MV. d. False. No association with alcohol has been shown. e. False. Male gender is associated with increased risk of difficult MV.
2. a. True. Hypoxia is an obvious complication from difficult MV and may lead to myocardial ischaemia and hypoxic brain injury. b. False. There is no association between difficult MV and brachial plexus injury. c. True. There is a strong association with high inflation pressures in difficult MV and aspiration risk. d. True. This occurs from direct pressure from the mask or from the drying effect of the gases used. e. False. No association has been shown.
3. a. False. Deepening anaesthesia in an adequately paralysed patient will confer no benefit. b. True. This depends on the situation and how timely the patient can regain spontaneous breathing and airway patency before critical hypoxia develops. If the time frame permits, then rapid reversal of neuromuscular blockade (i.e. sugammadex), benzodiazepine and opioid may be considered. However, if the likelihood of the patient regaining spontaneous airway patency is low (e.g. no readily available reversal agents), then the priority will be to obtain an airway and oxygenate the patient. c. True. An attempt at laryngoscopy would be appropriate, as it would allow oxygenation and ventilation if successful. d. True. An attempt at inserting a SAD is also appropriate as it may improve oxygenation and allow you to awaken the patient. This can also be used after a failed attempt at intubation. e. False. A surgical airway would be the final step after attempting SAD insertion or intubation.
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References 1. American Society of Anesthesiologists Task Force on Management of the Difficult Airway. Practice guidelines for management of
the difficult airway: an updated report by the American Society of Anesthesiologists Task Force on Management of the Difficult Airway. Anesthesiology 2013; 118:251-270.
2. Langeron O, Masso E, Huraux C, Guggiari M, Bianchi A, Coriat P, Riou B. Prediction of difficult mask ventilation. Anesthesiology
2000;92:1229-36.
3. Yildiz TS, Solak M, Toker K. The incidence and risk factors of difficult mask ventilation. J Anesth 2005;19:7-11.
4. Kheterpal S, Han R, Tremper KK, Shanks A, Tait AR, O’Reilly M, Ludwig TA. Incidence and predictors of difficult and impossible mask ventilation. Anesthesiology 2006;105:885–91.
5. El-Orbany M, Woehlck H. Difficult mask ventilation. Anesth Analg 2009;109:1870-1880.
6. Han R, Tremper KK, Kheterpal S, O’Reilly M. Grading scale for mask ventilation. Anesthesiology 2004;101:267.
7. Kheterpal S, Marin L, Shanks AM, Tremper KK. Prediction and outcomes of impossible mask ventilation: a review of 50,000
anaesthetics. Anesthesiology 2009;110:891-7.
8. Bennett JA, Abrams JT, Van Riper DF, Horrow JC. Difficult or impossible ventilation after sufentanil-induced anesthesia is caused primarily by vocal cord closure. Anesthesiology 1997; 87:1070-4
9. Royal College of Anaesthetists, Difficult Airway Society. 4th national audit project of major complications of airway management in
the United Kingdom. Available online from: http://www.rcoa.ac.uk/system/files/CSQ-NAP4-Full.pdf
10. Cattano D, Katsiampoura A, Corso RM, Killoran PV, Cai C, Hagberg CA. Predictive factors for difficult mask ventilation in the obese surgical population. F1000Res 2014;3:239.
11. Patel A, Nouraei S. Transnasal Humidified Rapid-Insufflation Ventilatory Exchange (THRIVE): a physiological method of increasing
apnoea time in patients with difficult airways. Anaesthesia 2015;70:323-329.
12. Difficult Airway Society, Association of Paediatric Anaesthetists. Difficult mask ventilation – during routine induction of anaesthesia in a child aged 1 to 8 years. Available online from: http://www.apagbi.org.uk/sites/default/files/images/APA1-DiffMaskVent-FINAL.pdf
13. Chrimes N, Fritz P. The vortex approach: Management of the unanticipated difficult airway. Available online from:
http://www.vortexapproach.com (accessed 20/09/15)
14. Kheterpal S, Healy D, Aziz MF, Shanks AM, Freundlich RE, Linton F, et al; Multicenter Perioperative Outcomes Group (MPOG) Perioperative Clinical Research Committee. Incidence, predictors, and outcome of difficult mask ventilation combined with difficult laryngoscopy: a report from the multicenter perioperative outcomes group. Anesthesiology 2013;119:1360-1369.
Further reading • Adnet F. Difficult mask ventilation: an underestimated aspect of the problem of the difficult airway? Anesthesiology
2000;92:1217-8.
• Ramachandran S, Kheterpal S. Difficult mask ventilation: does it matter? Anaesthesia 2011;66(Suppl 2):40-44.
This work is licensed under the Creative Commons Attribution-NonCommercial 3.0 Unported License. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc/3.0/
Boone County Fire Protection DistrictEMS Education
Airway & Breathing Course
Boone County Fire Protection DistrictEMS Education
Airway & Breathing Course
Boone County Fire Protection DistrictEMS Education
G a n d P G r a t e d
m a t e r i a l
Boone County Fire Protection DistrictEMS Education
BLS Airway Unit
Sniffing Position Lesson
Jaw Thrust / Mask Seal Lesson
OPA / NPA Lesson
Bag-Mask Ventilation Lesson
Boone County Fire Protection DistrictEMS Education
Jaw Thrust / Mask Seal
Boone County Fire Protection DistrictEMS Education
E-C Technique
Its in all the books!
Its not the most effective for the field.
All the standards talk about how the BVM is a TWO PERSON TOOL so why would you just use one hand for the airway?
Boone County Fire Protection DistrictEMS Education
Two Thumbs Down
Boone County Fire Protection DistrictEMS Education
Two Thumbs Down
Jaw Thrust
Mask Seal
Someone else can squeeze the bag!
Video link
Boone County Fire Protection DistrictEMS Education
Airway & Breathing Course
Boone County Fire Protection DistrictEMS Education
G a n d P G r a t e d
m a t e r i a l
Boone County Fire Protection DistrictEMS Education
BLS Airway Unit
Sniffing Position Lesson
Jaw Thrust / Mask Seal Lesson
OPA / NPA Lesson
Bag-Mask Ventilation Lesson
Boone County Fire Protection DistrictEMS Education
OPA / NPA
Boone County Fire Protection DistrictEMS Education
OPA
Adjunct to jaw thrust—not a replacement.
Great for those without a gag reflex!
Won’t work if there is a gag reflex.
If you try it and they gag—then they vomit—now things are worse.
Pinch their nailbed with the OPA to test.
Boone County Fire Protection DistrictEMS Education
NPA
Adjunct to jaw thrust—not a replacement.
Great for those WITH a gag reflex!
IF you can get into their nose.
If you guess wrong and its too long…withdraw it just a bit.
Nosebleed is not uncommon.
Boone County Fire Protection DistrictEMS Education
When in Doubt…
Nobody said you can’t use both OPA and NPA.
Caution—if you use two NPA then you probably can’t use IN route for meds.
Boone County Fire Protection DistrictEMS Education
Just Because…
OPA’s and NPA’s together may not be something that you see many field paramedics doing…
…but maybe they ought to.
If it works, your patient needs you to use it even if you partner thinks you are weird.
Boone County Fire Protection DistrictEMS Education
G a n d P G r a t e d
m a t e r i a l
Boone County Fire Protection DistrictEMS Education
BLS Airway Unit
Sniffing Position Lesson
Jaw Thrust / Mask Seal Lesson
OPA / NPA Lesson
Bag-Mask Ventilation Lesson
Boone County Fire Protection DistrictEMS Education
Sniffing Position
Boone County Fire Protection DistrictEMS Education
Ear-To-Sternal Notch
The line between the external auditory meatus (“ear hole”) to the sternal notch should be parallel to the plane of the patient’s face.
Boone County Fire Protection DistrictEMS Education
Sniffing Position
Boone County Fire Protection DistrictEMS Education
RampingUse towel(s) or blanket(s) or modules from your EMS Pack or whatever…
Boone County Fire Protection DistrictEMS Education
Ear-To-Sternal Notch
Just because you don’t see many field paramedics using this technique…doesn’t mean its not helpful and well worth the effort.
Not everything that they use in the OR is worthless in the field!
Boone County Fire Protection DistrictEMS Education
Airway & Breathing Course
Boone County Fire Protection DistrictEMS Education
G a n d P G r a t e d
m a t e r i a l
Boone County Fire Protection DistrictEMS Education
BLS Airway Unit
Sniffing Position Lesson
Jaw Thrust / Mask Seal Lesson
OPA / NPA Lesson
Bag-Mask Ventilation Lesson
Boone County Fire Protection DistrictEMS Education
Bag Mask Ventilation
Boone County Fire Protection DistrictEMS Education
Negative Pressure
We are negative pressure breathing animals…its how we were designed.
Air goes where we want it.
Pressure in the chest is how we need it.
Negative pressure breathing is positive for perfusion.
Boone County Fire Protection DistrictEMS Education
Positive Pressure
Positive Pressure Ventilation causes NEGATIVE perfusion effects.
Air goes where it wants to—stomach is the easiest pathway.
Sometimes we must ventilate—so we must ventilate correctly.
Boone County Fire Protection DistrictEMS Education
Rate
SLOW is good.
One breath NO MORE OFTEN THAN every SIX seconds.
Boone County Fire Protection DistrictEMS Education
Pressure
LOW is good.
Smooth squeeze—especially before intubated.
Boone County Fire Protection DistrictEMS Education
Volume
ONE hand, HALF the Bag.
200 pound patient needs 700cc tidal volume from the 1500cc bag.
Boone County Fire Protection DistrictEMS Education
Just Because…
…you have always done it wrong or
…you see some “senior” medics do it
Does NOT make it the best thing for your patient.
New evidence and standards support what we are teaching.
SMAR
T BA
G® M
O h
as b
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desi
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llow
the
prov
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n of
con
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lmos
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ven
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Th
e si
mpl
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the
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PON
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By
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xces
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risk
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astri
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suffl
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ef
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gen
erat
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a no
rmal
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plia
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nd re
sist
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irway
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ssur
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nera
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imite
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ower
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opha
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peni
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sure
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onse
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SMAR
T BA
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ropo
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o th
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quee
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ART
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O, a
llow
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ntila
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ven
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mos
t re
stric
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airw
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aid
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resc
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a vis
ual
war
n-in
g of
inco
rrect
ope
ratio
n of
the
bag
is p
rovi
ded.
If
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the
SMAR
T BA
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resp
onds
by
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val
ve t
o lo
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rate
. Sh
ould
thi
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cur
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“red
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ssur
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ctua
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oves
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he n
eck
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he p
atie
nt v
alve
pro
vidi
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vis
ual
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mpr
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tech
niqu
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Sinc
e its
int
rodu
ctio
n, t
he B
ag-V
alve
-Mas
k re
susc
itato
r (o
r BV
M)
has
been
the
mai
nsta
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em
erge
ncy
vent
ila-
tion
in b
oth
the
pre-
hosp
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and
hosp
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envi
ronm
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. H
owev
er, t
he c
linic
al e
vide
nce
rega
rdin
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e pe
rform
ance
of
thes
e de
vice
s ho
wev
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how
s a
mar
ked
lack
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er th
e ve
ntila
tion
para
met
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in
the
hand
s of
th
e m
ajor
-ity
of
user
s.1,
2,3,
4,5,
6 Mor
e re
cent
re
sear
ch h
as c
ompo
unde
d th
is
lack
of
su
ppor
ting
evid
ence
re
gard
ing
the
effic
acy
of th
ese
devi
ces
with
stu
dies
that
hav
e sh
own
the
clin
ical
ly d
etrim
enta
l ef
fect
s of
wha
t is
now
term
ed,
Inad
verte
nt H
yper
vent
ilatio
n.
This
com
mon
phe
nom
enon
is
defin
ed
as
the
unin
tent
iona
l (in
volu
ntar
y,
acci
dent
al
or
not
delib
erat
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eliv
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of a
n ex
cess
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min
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volu
me.
It
is
likel
y to
ha
ve
detri
men
tal
hem
odyn
amic
an
d su
rviv
al
cons
eque
nces
in
pa
tient
s in
lo
w fl
ow s
tate
s su
ch a
s du
ring
CPR
or
hypo
vole
mia
due
to
traum
a.
Gas
tric
insu
fflat
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and
the
asso
ciat
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sk o
f asp
iratio
n of
st
omac
h co
nten
ts,
decr
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d co
rona
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perfu
sion
pr
essu
re10
and
incr
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d br
ain
isch
aem
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ar
e al
l sho
wn
to b
e ca
used
by
inad
verte
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vent
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decr
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co
rona
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a r
esul
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th
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echa
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f th
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art
by e
ither
too
la
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a tid
al v
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e de
liver
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“b
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me
allo
wed
for
the
lung
s to
fully
em
pty
resu
lting
in
the
subs
eque
nt b
reat
h be
ing
“sta
cked
” on
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sidu
al v
olum
e fro
m th
e pr
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ing
brea
th).
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ease
d br
ain
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a
func
tion
of e
xces
sive
CO
2 re
mov
al c
reat
ing
an i
ncre
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in c
ereb
ral v
asoc
onst
rictio
n.
Add
to
th
ese
issu
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poor
ox
ygen
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d th
e af
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on
patie
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outc
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com
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ifica
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ven
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int o
f con
tibut
ing
to th
e cu
rrent
ly
poor
sur
viva
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es fr
om C
ardi
ac A
rrest
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THE
PRO
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MTH
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LUTI
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Bag
Val
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ask
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ilatio
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PATI
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WIT
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OO
R C
OM
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NC
E / H
IGH
AIR
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ESIS
TAN
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patie
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airw
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a hi
gher
pre
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an n
orm
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equi
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verc
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high
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l-an
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flow
thro
ugh
the
valv
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low
ing
the
resc
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o ap
ply
high
er fl
ows
to th
e ai
rway
and
ade
quat
ely
vent
ilate
the
patie
nt.
NO
TE: T
his
incr
ease
in a
irway
pre
ssur
e re
quire
d to
pro
vide
ade
quat
e ve
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allo
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as to
be
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patie
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mac
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th
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phin
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OR
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resc
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sure
is m
aint
aine
d be
low
low
er e
soph
agea
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hres
hold
pre
s-su
re.
PATI
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WIT
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OR
MA
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OM
PLIA
NC
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rate
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stric
ted
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BA
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mai
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low
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vis
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rwar
d in
to th
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tient
val
ve
rem
indi
ng th
e re
scue
r to
redu
ce th
e fo
rce
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g ap
plie
d to
the
bag.
THE
USE
OF
MA
NU
AL
OVE
RR
IDE
CO
NTR
OL
Cur
rent
res
earc
h in
dica
tes
that
, for
all
patie
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ondi
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anua
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rrid
e co
ntro
l sho
uld
NO
T B
E U
SED
and
th
e “S
MA
RT
VALV
E” s
houl
d be
left
in th
e “E
NA
BLE
D”
posi
tion.
Thi
s re
com
men
datio
n m
aint
ains
ope
ratio
n of
th
e SM
AR
T B
AG®
M
O
in
stric
t co
mpl
ianc
e w
ith
the
curr
ent
Gui
delin
es
for
CP
R
and
EC
C
as
publ
ishe
d by
the
Am
eric
an H
eart
Ass
ocia
tion
and
the
Eur
opea
n R
esus
cita
tion
Cou
ncil.
Sho
uld
the
oper
ator
dec
ide
to u
se t
he m
anua
l ov
errid
e co
ntro
l, it
is im
porta
nt n
ot s
witc
h in
to t
he d
isab
led
mod
e w
hile
squ
eezi
ng th
e ba
g. U
sing
the
SMA
RT
BA
G®
MO
in
the
“SM
AR
T VA
LVE”
“EN
AB
LED
” m
ode
may
res
ult
in
“Inad
verte
nt h
yper
vent
ilatio
n” w
ith a
ll its
ass
ocia
ted
risks
.
Ref
eren
ces:
1. A
.H.A
G
uide
lines
fo
r C
ardi
opul
mon
ary
Res
usci
tatio
n an
d E
mer
genc
y C
ardi
ac
C
are
– 20
052.
Elli
ng
R,
Pol
itis
J.
An
eval
uatio
n of
em
erge
ncy
med
ical
te
chni
cian
s’
abili
ty
to
use
man
ual v
entil
atio
n de
vice
s.
A
nn E
mer
g M
ed. 1
983;
12:7
65-7
683.
Hes
s D
, B
aran
C
. V
entil
ator
y vo
lum
es
us
ing
mou
th
to
mou
th,
mou
th
to
mas
k
and
bag-
valv
e-m
ask
tech
niqu
es
A
m J
Em
erg
Med
198
5;3:
292-
296.
4. J
esud
ian
MC
, H
arris
on
RR
, K
eena
n R
L,
M
aull
Kl. B
ag-v
alve
-mas
k ve
ntila
tion:
two
resc
uers
are
bet
ter t
han
one:
pre
limin
ary
repo
rt. C
rit C
are
Med
. 198
5;13
:122
-123
5. W
heat
ley
S,
Thom
as
AN
, Ta
ylor
R
J,
Br
own
T. A
com
paris
on o
f thr
ee m
etho
ds
of
ba
g va
lve
mas
k ve
ntila
tion.
Res
usci
tatio
n 19
97 J
an;3
3(3)
:201
-10
6. F
uers
t R
S,
Ban
ner
MJ,
M
elke
r R
J.
Insp
irato
ry ti
me
influ
ence
s th
e
dis
tribu
tion
of v
entil
atio
n to
the
lung
s an
d
sto
mac
h:
Im
plic
atio
ns fo
r C.P
.R. P
rese
nted
at
th
e S
ocie
ty
for
Aca
dem
ic
Em
erge
ncy
Med
icin
e A
nnua
l Mee
ting,
May
199
2.7.
Auf
derh
eide
T. e
t al:H
yper
vent
ilatio
n-
In
duce
d H
ypot
ensi
on D
urin
g
Car
diop
ulm
onar
y R
esus
cita
tion.
Circ
ulat
ion
Apr
il 27
, 200
4 8.
Bra
in T
raum
a Fo
unda
tion.
Gui
delin
es fo
r
the
Man
agem
ent o
f Sev
ere
Hea
d In
jury
-
1995
9. P
itts
and
Kel
lerm
an. E
dito
rial i
n th
e
Lanc
et J
uly
24th
200
5
RES
PON
DIN
G T
O Y
OU
R P
ATI
ENT
If th
e pa
tient
’s a
irway
is le
ss c
ompl
iant
or
mor
e re
stric
tive
(as
in p
atie
nts
with
CO
PD
or
asth
ma)
, hi
gher
airw
ay
pres
sure
s w
ill b
e re
quire
d to
pro
vide
ade
quat
e ve
ntila
tion.
In r
espo
ndin
g to
thi
s in
crea
sed
pres
sure
req
uire
men
t in
th
e pa
tient
’s a
irway
, the
SM
AR
T B
AG®
MO
allo
ws
the
user
to
incr
ease
the
pres
sure
requ
ired
to o
verc
ome
the
resis
tanc
e/co
mpl
ianc
e pr
oble
m a
nd p
rovi
de a
dequ
ate
ven
tilatio
ns.
Rem
embe
r th
at t
he S
MA
RT
BAG
® M
O w
ill o
nly
allo
w
you
to a
pply
hig
her
flow
rate
s ge
nera
ting
high
er a
irway
pr
essu
res
whe
n th
e pa
tient
’s a
irway
con
ditio
n re
quire
s th
em.
You
w
ill
“feel
” th
is
chan
ge
in
com
plia
nce
and
resi
stan
ce a
s th
e SM
AR
T B
AG
® M
O a
llow
s th
e hi
gher
flo
wra
tes
to b
e ge
nera
ted.
NO
TE: I
n th
e un
prot
ecte
d ai
rway
, as
with
any
res
usci
tatio
n de
vice
, th
e ris
k of
gas
tric
insu
fflat
ion
will
incr
ease
if th
e de
liver
ed fl
owra
te in
crea
ses
the
airw
ay
pres
sure
gen
erat
ed a
bove
the
LES
ope
ning
pre
ssur
e .
PRO
VID
ING
CO
NTR
OLL
EDVE
NTI
LATI
ON
By “
self
adju
stin
g” t
o bo
th t
he
patie
nt a
nd t
he r
escu
er,
the
SMA
RT
BA
G®
MO
opt
imiz
es
the
vent
ilatio
ns, c
ontro
lling
the
insp
irato
ry t
ime
and
keep
ing
the
deliv
ered
flo
wra
te
and
subs
eque
nt a
irway
pre
ssur
e to
the
min
imum
req
uire
d fo
r ad
equa
te v
entila
tion
to o
ccur
. Th
is
resu
lts
in a
sig
nific
ant
redu
ctio
n in
th
e ris
k of
ga
stric
in
suffl
atio
n an
d it’
s as
soci
ated
com
plic
atio
ns.
USIN
G T
HE S
MAR
T BA
G® M
O
Usi
ng th
e SM
AR
T B
AG
® M
O
is
EASY
! Ju
st
let
SMA
RT
BA
G®
M
O
com
pres
s un
der
your
ge
ntle
, sl
ow,
hand
sq
ueez
e. A
one
or t
wo-
hand
ed
sque
eze
can
be u
sed.
The
Insp
irato
ry t
ime
shou
ld b
e 1
seco
nd i
n ac
cord
ance
w
ith th
e cu
rren
t int
erna
tiona
l res
usci
tatio
n gu
ide
lines
.
TRA
ININ
G A
ND
SK
ILL
RET
ENTI
ON
Man
y re
fere
nces
exi
st a
s to
the
abili
ty o
f res
cuer
s to
ad
equa
tely
per
form
pra
ctic
al s
kills
. In
addi
tion,
the
rete
ntio
n of
thos
e sk
ills
and
the
abili
ty to
ade
quat
ely
perfo
rm th
em,
over
time,
dec
reas
es w
ithou
t fre
quen
t re
-trai
ning
and
edu
ca-
tion.
By
impa
rtin
g a
degr
ee o
f co
ntro
l fo
r th
e re
scue
r th
e SM
ART
BAG
® M
O h
elps
to
train
the
res
cuer
to
prov
ide
slow
con
sist
ent
vent
ilatio
ns. I
n ad
ditio
n, th
e SM
AR
T B
AG®
MO
cont
inua
lly re
-trai
ns th
e re
scue
r eve
ry ti
me
they
use
the
devi
ce b
y im
parti
ng th
at s
ame
degr
ee o
f con
trol d
urin
g re
sus-
cita
tion.
SMAR
T Va
lve
“Dis
able
d,” S
MAR
T BA
G® M
O re
spon
ds li
ke a
st
anda
rd B
VM.
SMA
RT
VALV
E En
able
dSM
AR
T VA
LVE
Dis
able
d
NO
TES:
[1]
Beca
use
of th
e un
ique
nat
ure
of th
e SM
AR
T B
AG
®
MO
, new
use
rs w
ill re
quire
min
imal
orie
ntat
ion
in th
e
use
of th
e de
vice
.
[2]
The
resu
scita
tor i
s no
t int
ende
d fo
r use
dur
ing
spon
tane
ous
brea
thin
g. D
ue to
the
natu
re o
f the
se
devi
ces,
they
may
onl
y pr
ovid
e a
rest
ricte
d flo
w o
f air
to
the
patie
nt a
nd li
ttle
or n
o su
pple
men
tal o
xyge
n.