Airway management/respiratory failure case file

Airway management/respiratory failure case file

Eugene C. Toy, MD, Barry C. Simon, MD, Terrence H. Liu, MD, MHP, Katrin Y. Takenaka, MD, Adam J. Rosh, MD, MS

Case 54

An 87-year-old man with a past history of stroke is brought in by ambulance from a skilled nursing facility after being found unresponsive in bed with rapid, shallow breathing. In the past 3 to 4 days he has had a wet sounding cough. Paramedics report his room air saturation in the field was 67%. In the emergency department he is obtunded with sonorous respirations, labored breathing and copious thick yellow secretions. His vital signs are the following: temperature 38.7°C, BP 90/58 mm Hg, P 118 bpm, RR 29 breaths per minute and oxygen saturation 84% on a non-rebreather face mask.

⯈ What is the immediate first step in the management of this patient?

⯈ What special factors need to be considered?

ANSWER TO CASE 54:

Airway Management/Respiratory Failure

Summary: This patient is an elderly male with a depressed level of consciousness, hypoxia, respiratory distress and pooling secretions. He is not oxygenating well or protecting his airway from aspiration.

• First step: This patient needs immediate airway management and endotracheal intubation.
• Additional factors: As a critically ill patient from a nursing facility, it is important to attempt to verify his code status before intubating. It is also important to consider the underlying causes for his altered mental status and respiratory distress.

ANALYSIS

Objectives

1. Learn how to evaluate the airway and indications for intervention.
2. Become more familiar with emergency airway procedures.
3. Understanding of the rationale for and the steps involved with rapid sequence intubation.
4. Recognize and anticipate the potentially difficult airway and special circumstances.

Considerations

In the case above, the patient has several concerning findings indicating he will need active airway management. He is hypoxic, tachypneic, and with his altered mental status he may not able to protect his airway from secretions or emesis. Because of his depressed level of consciousness and inability to protect his airway he is not an appropriate candidate for noninvasive positive pressure ventilation (such as BiPAP).

He likely has a pneumonia and/or aspiration event, but it is also important to consider that he may have had a separate preceding event such as a cerebral vascular accident or medication overdose which created the altered mental status before aspirating. His other vital signs indicate that he is probably septic and will need to be resuscitated after his airway is addressed.

Approach To:

Airway Management

CLINICAL APPROACH

Evaluation

Assessing a patient airway and breathing are critical first steps in evaluating any patient in the emergency department. Begin by grossly observing the appearance of the patient paying particular attention to key markers of oxygenation and ventilation: skin color looking for the presence of cyanosis, evidence of severe bronchospasm such as intercostal retractions, difficulty speaking, low or falling oxygen saturation, increased or decreased respiratory rate. Evaluation of the airway includes not just the actual structures of the head and neck but also the patient mental status and amount of secretions or blood present in the airway.

Indications for active airway intervention:

Respiratory Failure: persistent and or worsening hypoxia, severe hypercarbia/respiratory acidosis.

Airway Protection: absent gag, depressed level of consciousness, excess secretions.

Impending or existing airway obstruction: mass, infection, angioedema, foreign matter or excess secretions, etc.

Facilitation of further studies or to protect the airway during transport when deterioration may be anticipated.

Airway Protection There are several signs of an inadequately protected airway which indicate need for intubation: pooling secretions (eg, gurgling sounds with respiration), an absent or weak cough reflex and depressed mental status often correlating with GCS of 8 or less. In general, a patient whose level of consciousness is depressed enough to tolerate insertion of an oropharyngeal airway is not protecting his or her airway and requires airway protection.

Reversible and or transient causes of a decreased level of consciousness must be considered prior to active airway intervention. Treating hypoglycemia or suspected opiate overdose before intubating can save the patient a major intervention. Additionally, providers should consider that the patient may be postictal because they may improve rapidly to a point where they can protect their airway.

Respiratory Failure Respiratory failure refers to either failure to oxygenate or failure to ventilate. Failure to oxygenate is reflected by hypoxia despite maximum supplemental oxygen administration. Failure to ventilate, indicated by elevated levels of carbon dioxide (measured on blood gas or capnography) can be equally lifethreatening and requires intervention. Hypercapnea may manifest as somnolence, agitation or otherwise altered mental status.

In select patients who are awake and alert, noninvasive positive pressure ventilation (BiPAP) may be an option to delay or prevent intubation in the setting of hypoxic or hypercapneic respiratory failure.

Anticipated Clinical Deterioration There are several clinical scenarios in which awake patients without current respiratory failure may still require intubation. The emergency physician needs to anticipate the potential clinical course of a patient and may wish to “intubate early” to avoid less controlled intubation conditions later. Situations in which this may be considered include worsening airway obstruction such as in patients with anaphylaxis, angioedema, severe burns or smoke inhalation, penetrating neck trauma with an expanding neck hematoma, epiglottitis or deep space neck infections. Clinical scenarios that require the transfer of critically ill patients to a higher level of care requires a great deal of caution. If deterioration of the mental or respiratory status is anticipated it may be prudent to proceed with intubation prior to transfer.

Facilitation of Medical Evaluation Occasionally patients require intubation to safely complete necessary studies or procedures. One such scenario is that of a trauma patient who may be agitated or combative. These patients often require emergent CT imaging as part of their initial workup. If they require sedation to facilitate adequate imaging or procedures, intubation may be required for airway protection. Often these patients can be promptly extubated after completion if they are without respiratory issues.

Interventions Airway management is much more than just intubation. It can be as simple as providing supplemental oxygen or repositioning the patient. Knowledge of minimally invasive maneuvers and devices is critical and can be lifesaving.

Supplemental Oxygen Supplemental oxygen can be delivered (in order of increasing delivery) via nasal cannula, face mask, non-rebreather mask and high-flow nasal cannula. These are appropriate first steps for patients that are hypoxic but are otherwise protecting their airway. Supplemental oxygen is appropriate to treat hypoxemia and is indicated as part of one preparation for intubation should it become necessary.

Airway Positioning Positioning of patient with a depressed level of consciousness or with significant somnolence can be very important. The most common cause of airway obstruction in the semiconscious or unconscious patient is loss of muscle tone, causing the tongue and soft tissue to occlude the airway. The simplest corrective maneuver is the chin lift (see Sec I, Emergency Assessment and Management), opening the airway through neck hyperextension. This maneuver is contraindicated in patients with a suspected cervical spine injury. A jaw thrust (see Figure I–2) can also be performed by placing two or three fingers behind the angle of the mandible and lifting anteriorly. Since neck manipulation is not required, this maneuver can be safely performed in the context of cervical spine injury.

Other obstructive processes such as mediastinal masses, very large tonsils or morbid obesity may also require an upright position. A patient in respiratory failure from pulmonary edema will likely not tolerate laying flat and it is important to allow them to be upright.

Airway Adjuncts In addition to airway repositioning, placement of an oropharyngeal (OPA) and or nasopharyngeal airway (NPA) is required and may be highly effective. An OPA is designed to keep the tongue from obstructing the posterior pharynx. This device is only used in unconscious patients who do not have a cough or a gag reflex. Using an appropriately sized OPA is important: a device which is too small will be ineffective while an overly large OPA can worsen obstruction. It is particularly important to have an OPA in place when giving positive pressure ventilations (PPV) through a bag valve mask. Otherwise, external pressure on the patient chin may force the tongue into an obstructive position.

In the semiconscious patient with an intact gag reflex, insertion of an OPA can induce vomiting and possible aspiration. An NPA is the more appropriate adjunct for the semiconscious patient as it rarely induces gagging. The NPA functions by helping bypass tongue obstruction. It is contraindicated in patients with severe facial trauma due to the risk of brain intrusion.

Suctioning along the sides of the mouth is also important in patients with pooling secretions. The suction device should not be inserted deep into the oropharynx where it is likely to induce gagging and emesis.

Noninvasive Positive Pressure Ventilation Noninvasive positive pressure ventilation (NIPPV) is often used in the emergency department. NIPPV is the use of mechanical ventilatory support without an invasive airway in place such as an endotracheal tube. A tightly secured mask is the most common method used to deliver NIPPV. There are several varieties of masks and ventilatory modes used to deliver NIPPV. The two most commonly seen in the emergency department are continuous positive airway pressure (CPAP) and bi-level positive airway pressure (BiPAP). In the appropriately selected patient its use may prevent the need for intubation. Current evidence suggests the patients most likely to respond to NIPPV have conditions such as chronic obstructive pulmonary disease and cardiogenic pulmonary edema. Other clinical indications include severe respiratory acidosis, hypoxia, dyspnea, tachypnea and increased work of breathing.

Absolute contraindications to NIPPV include coma, cardiac arrest, respiratory arrest and any condition warranting immediate intubation. Relative contraindications include evidence of airway obstruction, cardiac instability (shock requiring pressors, ventricular dysrhythmias), GI bleeding, inability to protect airway, and status epilepticus.

Intubation As discussed above, the indications for endotracheal intubation may be straight forward and objective or subtle and vague. The need is obvious when there is clear failure to oxygenate or ventilate using less invasive means. Decision making is far more difficult when the clinical indications are less extreme.

Crash intubations are indicated in pulseless, and apneic patients, often without the use of preoxygenation or medications. Urgent intubations refer to patients needing intubation within minutes rather than seconds and do allow for the use of preoxygenation and induction medication. Stable patients who are likely to require active airway protection allow for a trial of alternative treatments and careful preparation.

RAPID SEQUENCE INTUBATION

What Is It?

Rapid sequence intubation (RSI) is a method that attempts to simultaneously sedate and paralyze a patient while creating optimum intubating conditions. The major goal is to leave the airway unprotected for the shortest time possible. The procedure assumes that the patient may have a full stomach and is at great risk of vomiting and aspiration. Rapid sequence intubation is one of the most important skills for the emergency physician and requires careful but quick preparation.

What Are the Steps of Rapid Sequence Intubation?

Once it has been determined a patient needs endotracheal intubation, if time allows, there are several key steps to follow. These are widely known as the “seven Ps” and are presented in temporal sequence below.

Step 1: Preparation:

Assess the Patient Is the patient a good candidate for RSI? Remember, the patient will be paralyzed and the physician is taking complete control over the airway. The question should always be asked how likely is the intubation to be successful? Can the patient be ventilated with a bag-valve-mask (BVM) if RSI should fail? Does the patient have dentures that need to be removed? Does the patient have signs of upper airway obstruction, such as drooling or stridor, due to edema, trauma, or mass? Is there any restriction of neck mobility? Heavy facial hair, a short thick neck, a recessed chin, or a large tongue should all be considered as potential impediments to bag-valve-mask ventilation or oral tracheal intubation. Examine the neck for surgical scars. A scar from a prior cricothyroidotomy is a concerning sign. Severe kyphosis or cervical spine immobilization will make intubation more difficult.

There are a few rules of airway evaluation that may be helpful in alert and cooperative patients. The first is the 3-3-2 rule. The patient should be able to insert at least 3 fingers into his/her mouth in the vertical orientation, between the upper and lower front teeth; the hyomental distance (from the hyoid cartilage to the chin) should be at least 3 fingers breadth; and there should be at least 2 fingers breadth between the floor of the mouth and the thyroid cartilage. The Mallampati score is another means of predicting intubation difficulty. The patient is asked to stick out his/her tongue while opening the mouth wide as possible. The amount of posterior pharynx visible is divided into four classes. The best view is referred to as “class one” including full visibility of the tonsils, uvula, and soft palate. The more limited classthree and class-four views may be associated with difficult intubations.

Concerns that the patient is not a good candidate for RSI should prompt immediate consultation with an anesthesiologist. A surgeon should also be emergently consulted if a cricothyroidotomy is likely.

Prepare Materials It is essential that all equipment is available and working before embarking on this procedure. Necessary pre-intubation equipment includes oral and nasal pharyngeal airways, suction, oxygen, and a bag valve mask. Basic intubation equipment includes a laryngoscope handle and several blades. The most commonly

used laryngoscope blades are the curved Macintosh blade and the straight Miller blade. They should be tested for adequate light function before use.

Endotracheal tubes (ETT) of various sizes and stylets must also be ready for use. The ETT has a distal balloon that should be inflated and deflated before use to test for leaks. The ETT should be preloaded with an internal stylet and is typically bent in the shape of a hockey stick to allow it to pass more anteriorly. Several other ETTs, at least a 1/2 size larger and smaller, should also be available. The formula used to predict endotracheal tube size for children ages two and older: (age in years + 16)/4.

Airway “rescue” devices should be available and familiar to the provider to be used in difficult intubation scenarios. These devices include bougies, a video laryngoscope and several sizes of laryngeal mask airways (LMA). Cricothyroidotomy materials should always be nearby.

The medications selected for induction and paralysis should be drawn up and ready. The patient should be attached to a cardiac monitor with frequently cycling blood pressure, a pulse oximeter, and an end-tidal CO2 monitor. Importantly, the patient must have a freely flowing IV. These steps are summarized by the mnemonic SOAP ME IV (Table 54–1).

Step 2: Preoxygenation Preoxygenation is a key part of RSI and should be started when one is even considering the need for active airway management. The purpose of preoxygenation is to allow for a greater reservoir of oxygen in the lungs via nitrogen washout. Three to five minutes of high-flow O2 is adequate and allows for a substantial apneic period without oxygen desaturation in otherwise healthy patients (see Figure 54–1). Pre-oxygenating with high-flow oxygen requires that the patient is breathing. If the patient is apneic, studies have shown that 8 full-volume BVM ventilations over 1 minute are equivalent. Yet bag-valve-mask ventilation of the spontaneously breathing patient is contraindicated because it unnecessarily increases the risk of gastric distension and aspiration.

Step 3: Pretreatment Pretreatment is a controversial topic that deserves brief mention. Manipulation of the airway causes a transient increase in intracranial pressure (ICP). In patients who may already have increased ICP (eg, in intracerebral hemorrhage), any further increase could be potentially devastating. Several medications may be used in sequence in attempt to diminish the effect of airway manipulation on intracranial pressure. Starting a few minutes before induction, fentanyl (3-5 μg/kg) followed by lidocaine (1.5 mg/kg), and a defasciculating dose of the paralytic agent (1/10th the treatment dose) may be given. However, there are

Figure 54–1. Hemoglobin Desaturation Curve.

conflicting data regarding the potential benefit with the use of these medications. In addition, pretreatment may lead to other complications and a delay in intubation.

Step 4: Induction and Paralysis Induction involves administering a medication that will quickly and reliably sedate the patient prior to paralysis. Ideally, the sedative agent will have little effect on heart rate or blood pressure or cause other adverse side effects.

The induction agent most commonly used in emergency medicine is etomidate (0.3 mg/kg) as it meets these criteria well. It is rapidly sedating and hemodynamically neutral. It is also thought to be cerebroprotective. A potential downside of etomidate is that it causes transient adrenal suppression. Although the clinical significance of this effect is uncertain, some physicians avoid etomidate when intubating septic patients.

Ketamine is another drug that may be used for induction, ideally suited for patients in status asthmaticus, anaphylactic shock, and sepsis. Ketamine is a derivative of PCP and acts as a dissociative agent. It has rapid onset of action (1.5 mg/kg IV) and causes increases in blood pressure and heart rate through catecholamine release. It is unique in that it leaves airway reflexes protected and does not induce apnea. Additionally, it has bronchodilatory and analgesic properties. It should be used with caution in patients with known coronary artery disease.

Propofol and thiopental are other fast-acting sedative agents of short duration, but less commonly used in RSI due to associated hypotension.

Paralysis Paralytic drugs come in two basic types—depolarizing and nondepolarizing, describing their action at the neuromuscular junction. The only depolarizing agent in common clinical use is succinylcholine which has the most rapid onset and shortest duration of all paralytics. It is an analogue of acetylcholine and acts by transiently binding to ACh receptors, keeping ion channels open, leading to paralysis. Succinylcholine action at the motor endplate causes potassium efflux, and therefore should be avoided in patients with hyperkalemia. Succinylcholine and its effects on extracellular potassium levels may be pronounced and should be avoided in patients with recent or ongoing neuromuscular disorders, subacute burns, severe debilitation, crush injuries, or rhabdomyolysis. Acute head injury, acute burns, and acute strokes are not contraindications to the use of succinylcholine.

Nondepolarizing agents act by competitive inhibition of the postsynaptic acetylcholine receptor, thereby preventing depolarization and causing paralysis. The agents most commonly used are rocuronium and vecuronium. Rocuronium is preferred for RSI among the nondepolarizing agents as it has the most rapid onset and shortest duration.

Step 5: Positioning and Protection Patient positioning for RSI is an extremely important but often overlooked step in the emergency department. The proper head position in adults is the “sniffing” position, with the base of the neck flexed forward and the head hyperextended. When done properly, the patient ear should be at the level of the sternum. This position greatly enhances the view of the vocal cords from the mouth. Prior to administration of medications, the patient head should be positioned at the very end of the bed, and the bed height should be adequate for the operator. Once induction agents are given, firm downward pressure to the cricoid cartilage (known as the Sellick maneuver) is often done to prevent gastric distention and possible aspiration. However, recent studies have suggested that this may not be necessary and can worsen the view of the operator.

Step 6: Placement with Proof Once the patient is paralyzed and positioned, the ETT should be placed without delay. The first step is to open the patient mouth and insert the laryngoscope blade along the right side deep into the posterior oropharynx, then move to the center sweeping the tongue out of the way while lifting up and out. This usually provides a view of the vocal cords. The ETT is advanced until the balloon is just beyond the vocal cords, then the operator must stop, inflate the balloon, and remove the stylet.

The next step is to confirm that the endotracheal tube is in the right place. The absolute best way to do this is to watch it pass through the cords. Other confirmatory measures (end-tidal CO2 change, fogging of the tube, and listening for breath sounds) should always be performed. However, these are nonspecific signs and can all be misleading in various circumstances.

Step 7: Postintubation Management Once placed and confirmed, the endotracheal tube must be secured. A chest x-ray is obtained to assess appropriate depth of the ETT. The chest x-ray is not useful for differentiating tracheal from esophageal intubation. Next, orders should be given for a longer acting sedative agent as well as analgesia. Finally, ventilator settings should be established which include the mode, respiratory rate, Fio2, tidal volume, and peak-end expiratory pressure. The 7 Ps for RSI are summarized in Table 54–4.

COMPREHENSION QUESTIONS

54.1 The best way to confirm endotracheal tube placement is

A. Chest x-ray

B. End tidal CO2

C. Breath sounds heard in both lung fields

D. Watching the ETT pass through the vocal cords

54.2 Which of the following is a contraindication to succinylcholine?

A. Acute burns

B. Acute renal failure

C. History of coronary artery disease

D. Sepsis

54.3 A 20-year-old man presents to the emergency department after being stung by a bee. His skin is red and covered with welts. He has obvious swelling of his lips and tongue, but no wheezes. After treatment with appropriate medications, he complains of throat swelling and his voice is hoarse. He has stridorous inspirations but a normal respiratory rate and oxygen saturation. What is the most appropriate management of this patient airway?

A. Continued observation as long as oxygen saturation remains normal

B. Call anesthesia and prepare for RSI.

C. Begin high-dose nebulized albuterol and continue to observe.

D. Prepare for cricothyroidotomy.

54.4 You are the first person on scene to a code blue in your hospital. You arrive to find an elderly woman who is unconscious, has a weak pulse and does not appear to be breathing. Your first steps are

A. Wait for the code cart to arrive and then intubate the patient.

B. Begin chest compressions and mouth-to-mouth resuscitation.

C. Attempt to remove any foreign body from the mouth and reposition the airway with chin lift or jaw thrust.

D. Begin bagging the patient immediately.

ANSWERS

54.1 D. Watching the ETT pass through the vocal cords is the best way to assure proper placement. CXR has no role in differentiating between endotracheal and esophageal intubation. The other choices are helpful but not failsafe.

54.2 B. Succinylcholine transiently increases serum potassium levels. It is presumptively contraindicated in renal failure patients who often have elevated potassium levels. Acute burns are not a contraindication. Beginning 2 to 3 days after a burn, acetylcholine receptor upregulation can lead to hyperkalemia. Neither coronary artery disease nor sepsis is a contraindication to the use of succinylcholine.

54.3 B. This patient displays signs of impending airway obstruction. His worsening airway edema, despite appropriate medical therapy, dictates intubation before complete airway occlusion and a cricothyroidotomy is required. There is no wheezing to suggest bronchoconstriction that could be treated with a bronchodilator such as albuterol. Stridor is a worrisome sign of upper airway obstruction. Normal respiratory rate and oxygen saturation should not delay intubation as falling oxygen saturation is a late sign of respiratory failure. Cricothyroidotomy is only indicated after all other measures have failed.

54.4 C. The most common cause of airway obstruction is the tongue and/or soft tissues of the upper airway. No other adjuncts may be necessary for initial management except relieving the obstruction with airway repositioning. This should certainly be the first step, and there is no need to wait for the code cart before performing this maneuver. There is no indication for chest compressions in a patient with palpable pulses. The patient will require BVM ventilation after airway repositioning and placement of an oral airway. If the patient is easy to ventilate, reversible causes of respiratory depression, such as a narcotic overdose, should be investigated and may eliminate the need for RSI.

CLINICAL PEARLS

⯈ Remember the noninvasive maneuvers and interventions that may eliminate the need for intubation: nasopharyngeal airways, chin lift, suction, BiPAP.

⯈ Always have suction available.

⯈ Bag-valve-mask ventilation is a lifesaving intervention for almost all patients with respiratory failure—know how to do it!

⯈ Use an oral airway when bagging a patient.

⯈ Head position is key for both basic and advanced airway management.

⯈ Take time to thoroughly prepare for RSI. Poor preparation should never be the reason for a failed airway.

⯈ Call anesthesia and/or surgery early if a difficult airway is anticipated.

⯈ Always anticipate the difficult airway and have back-up airway devices immediately available.

REFERENCES

Baraka AS, Taha SK, Aouad MT, et al. Preoxygenation: comparison of maximal breathing and tidal volume breathing techniques. Anesthesiology. 1999;91(3):612-616. 

Benumof JL, Dagg R, Benumof R. Critical hemoglobin destauration will occur before return to an unparalyzed state following 1 mg/kg intravenous succinylcholine. Anesthesiology. 1997;87(4):979-982. 

Butler J, Sen A. Best evidence topic report. Cricoid pressure in emeceny rapid sequence induction. Emerg Med J. 2005;22(11):815-816. 

Ellis DY, Harris T, Zideman D. Cricoid pressure in emergency department rapid sequence intubations: a risk-benefit analysis. Ann Emerg Med. 2007;50(6):653-665. 

Ray DC, McKeown DW. Effect of induction agent on vasopressor and steroid use, and outcome in patients with septic shock. Crit Care. 2007;11(3):R56. 

Robinson N, Clancy M. In patients with head injury undergoing rapid sequence intubation, does pretreatment with intravenous lidocaine lead to an improved neurological outcome? A review of the literature. Emerg Med J. 2001;18(6):453-457. 

Walls, R M. Rapid Sequence Intubation in Manual of emergency airway management, Phildelphia Lipencott Williams & Wilkens; 2004. 

Yeung JK, Zed PJ. A review of etomidate for rapid sequence intubation in the emergency department. CJEM. 2002;4(3):194-198.

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