Emergency cricothyrotomy (cricothyroidotomy) in adults

INTRODUCTION — Cricothyrotomy (also called cricothyroidotomy) is an infrequent procedure that involves placement of a tube through an incision in the cricothyroid membrane to establish an airway for oxygenation and ventilation. It is potentially life-saving in the patient with a "can't intubate, can't oxygenate" (CICO) situation during advanced airway management after non-surgical airway techniques have failed or as a primary technique when other non-surgical options are not felt to be appropriate. Conditions associated with a difficult airway that commonly necessitate cricothyrotomy include trauma (eg, facial fractures, traumatic airway obstruction), large amounts of blood or vomitus in the airway, trismus, obstructing lesions (eg, tumor, polyp), upper airway occlusion (foreign body, edema, anaphylaxis), failed orotracheal intubation, and congenital deformities [1,2].

Performance of cricothyrotomy in adults is reviewed here. Other aspects of difficult airway management, rapid sequence intubation, and needle cricothyrotomy in children are discussed separately.

●Difficult airway management in adults (see "Approach to the difficult airway in adults for emergency medicine and critical care" and "Devices for difficult airway management in adults for emergency medicine and critical care" and "Approach to the failed airway in adults for emergency medicine and critical care")

●Rapid sequence intubation in adults (see "Rapid sequence intubation in adults for emergency medicine and critical care" and "Induction agents for rapid sequence intubation in adults for emergency medicine and critical care" and "Neuromuscular blocking agents (NMBAs) for rapid sequence intubation in adults for emergency medicine and critical care")

●Needle cricothyrotomy in children (see "Needle cricothyroidotomy with percutaneous transtracheal ventilation")

●Rapid sequence intubation and difficult airway management in children (see "Technique of emergency endotracheal intubation in children" and "The difficult pediatric airway for emergency medicine" and "Supraglottic airway devices in children with difficult airways" and "Video laryngoscopy and other devices for difficult endotracheal intubation in children")

GENERAL CONSIDERATIONS IN FAILED AIRWAY SCENARIO — In a "can't intubate, can't oxygenate" (CICO) failed airway scenario, quickly establishing an airway is crucial since anoxic encephalopathy or death can occur within minutes of cerebral hypoxia.

●Call for assistance – Once a failed airway is recognized and a cricothyrotomy is contemplated, the clinician should avail themselves of all potentially helpful resources such as colleagues from emergency medicine, surgery, and anesthesia.

●Role of extraglottic airway devices – Placing an extraglottic airway device (eg, laryngeal mask airway) should be attempted as a rescue maneuver or as a bridge to provide ventilation while preparations are made to perform a cricothyrotomy. If oxygenation cannot be maintained, the cricothyrotomy procedure should not be delayed further. (See "Extraglottic devices for emergency airway management in adults".)

●Ensure neuromuscular blockade – Ensure that the patient is fully paralyzed with an appropriate neuromuscular blocking agent [3]. Complete neuromuscular blockade (with appropriate sedation) increases the likelihood of successful tracheal intubation, face mask ventilation, and extraglottic airway ventilation and thus facilitates management of a failed airway situation. (See "Neuromuscular blocking agents (NMBAs) for rapid sequence intubation in adults for emergency medicine and critical care".)

●Fundamental considerations – Once a cricothyrotomy is contemplated, the clinician must quickly address the following fundamental considerations:

•Will a cricothyrotomy effectively bypass the airway obstruction? As an example, if the obstruction is in the trachea distal to the cricothyroid membrane, performing a cricothyrotomy may not be effective. A surgical airway below the level of obstruction (eg, tracheotomy) may be the only way to establish oxygenation and ventilation.

•Will the patient's anterior neck anatomy make the procedure particularly difficult or time consuming? A mnemonic for difficult cricothyrotomy is presented in the table (table 1). These factors are not an absolute contraindication to a cricothyrotomy, but recognizing their presence allows for potentially mitigating their impact.

•Which cricothyrotomy technique is to be used? The technique with which the operator is familiar and will work in all patients should be used. A CICO scenario is not the appropriate time to be making decisions on which technique to employ given the high-pressure nature of this procedure. Any delays in successfully performing a cricothyrotomy increase the risk of worse outcomes from hypoxemia. As such, the clinician should learn and be intimately familiar with a single cricothyrotomy technique that they have practiced ahead of time. Other considerations include the following:

-We prefer the scalpel-finger-bougie technique for the default method since it is relatively simple, highly effective, and only requires equipment that is typically readily available in airway management situations. (See 'Preferred technique: Scalpel-finger-bougie' below.)

-The rapid four-step technique can be performed quickly and with fewer steps but requires favorable anatomy in which the cricothyroid membrane can be easily and reliably identified. A tracheal hook is also required, which may not be readily available. (See 'Rapid four-step technique' below.)

-The traditional open surgical technique involves more steps and requires equipment that may not be readily available such as a tracheal dilator (Trousseau dilator) and a tracheal hook. (See 'Traditional open technique' below.)

-Commercially available cricothyrotomy kits typically use a Seldinger technique with a guidewire (eg, Cook Melker kit) or a prefabricated percutaneous device (eg, Quicktrach II). These conveniently contain all essential equipment but evidence regarding performance is limited. (See 'Seldinger technique' below and 'Percutaneous with prefabricated devices' below.)

CONTRAINDICATIONS AND PRECAUTIONS

No absolute contraindications in adults — There are no absolute contraindications to emergency cricothyrotomy in adults. Age younger than five years is an absolute contraindication in children, which is discussed elsewhere. (See "The difficult pediatric airway for emergency medicine", section on 'Surgical airway'.)

Failure to rapidly perform a cricothyrotomy in a "can't intubate, can't oxygenate" (CICO) situation will result in anoxic encephalopathy and/or death.

Relative contraindications

●Fracture of the larynx, laryngotracheal disruption, or transection of the trachea with retraction of the distal trachea into the mediastinum – In such cases, tracheotomy or stabilization of the distal tracheal segment followed by direct intubation is the approach with the best chance to successfully establish an airway. (See "Penetrating neck injuries: Initial evaluation and management", section on 'Airway management'.)

●Bleeding diathesis – In a life-threatening circumstance, the need to establish an airway supersedes this concern.

●Young age – The age at which a cricothyrotomy can safely be performed is not well established, and recommendations vary from 5 to 12 years old. Age is not the only consideration, and others include the child's size and physical maturity, state of health, external landmarks of the neck (eg, nonpalpable cricothyroid membrane), clinical findings, and presence of trauma. In general, the preferred surgical airway technique in a young child is transtracheal oxygenation with a large bore angiocatheter or a tracheotomy since the cricothyroid membrane is not well developed in children. (See "Needle cricothyroidotomy with percutaneous transtracheal ventilation" and "The difficult pediatric airway for emergency medicine".)

CLINICAL ANATOMY

Anatomy of the cricothyroid membrane — Proper performance of a cricothyrotomy depends on understanding the relevant anatomy and the ability to identify the cricothyroid membrane (CTM), which is a relatively superficial anterior neck structure. Cricothyrotomy is guided by palpation rather than direct visualization.

The boundaries of the CTM are the thyroid cartilage superiorly, the cricoid cartilage inferiorly, and the articulation of the inferior edge of the thyroid cartilage and the superior edge of the cricoid ring laterally, which forms a rigid circular opening (figure 1 and figure 2). The cricothyroid arteries are branches of the superior thyroid arteries that course along both sides of the CTM and anastomose in the midline, closer to the superior border of the CTM (thus it is preferable to incise the inferior portion of the CTM) [4].

The dimensions of the CTM determine the maximum size of the tracheal tube that can be placed. In an adult cadaver study, the vertical CTM size was reported to vary from 8 to 19 mm (mean 13.7 mm) and the transverse size from 9 to 19 mm (mean 12.4 mm) [5]. A study using computed tomography scans in United Kingdom trauma patients reported the mean height to be much smaller at 8 mm in males and 6 mm in females, which may be too small for many available emergency cricothyroidotomy devices [6,7]. The mean depth of tissue overlying the CTM in adults is about 2.3 mm [8].

Surface anatomy of the anterior airway — The key anatomic landmarks (figure 2 and figure 3) are (from cephalad to caudad): hyoid cartilage, thyroid cartilage, cricothyroid membrane, cricoid cartilage, and the tracheal rings. The thyroid cartilage, cricoid cartilage, and tracheal rings support and protect the airway.

●Hyoid bone and thyroid cartilage – The laryngeal prominence forms the superior edge of the thyroid cartilage. There is often a prominent palpable V-shaped notch that is typically larger in males [9]. The vocal cords are within and protected by the thyroid cartilage. The hyoid bone lies cephalad to the thyroid cartilage. The hyoid bone can be mistaken for the thyroid prominence in patients without a prominent thyroid cartilage. Incisions in the thyrohyoid space are fraught with potential complications, such as damage to the vocal cords (since the incision and tube will be cephalad to them) or placing the tube too far posteriorly into the retropharyngeal space or esophagus. (See 'Complications' below.)

●Cricothyroid membrane – The CTM is located about 2 cm caudal to the laryngeal prominence and can be identified by a slight depression in this area. The anatomical relationship between the thyroid and cricoid cartilages and the CTM is the most important landmark when performing cricothyrotomy (figure 2).

●Cricoid cartilage – This is located caudal to the thyroid cartilage. It is a complete cartilaginous ring, shaped like a signet ring, with its widest part found posteriorly (figure 3).

●Trachea – The trachea is the caudal continuation of the larynx and no longer palpable as it enters the mediastinum. The trachea is comprised of a row of incomplete C-shaped cartilaginous rings that are bound by the trachealis muscle posteriorly.

Even though the CTM is relatively superficial, accurate identification is complicated by conditions that alter surface anatomy, such as obesity, edema, hematoma, and subcutaneous air. Several studies highlight the potential difficulty of identifying the CTM [9-12]. In an observational study, anesthesiologists and obstetricians correctly identified the CTM in only 20 percent (10/41) of non-obese female patients and in none (0/15) of the obese patients [9]. A similar study involving six patients found that anesthesiologists correctly identified the CTM 30 percent of the time [10]. A study in 50 volunteer adult patients found that none of three widely promulgated techniques for identifying the CTM was sufficiently accurate (accuracy ranged from 50 to 62 percent) [13].

ROLE OF ULTRASOUND FOR CRICOTHYROTOMY — Even though point-of-care ultrasound (POCUS) can help identify the cricothyroid membrane (CTM), once a "can't intubate, can't oxygenate" (CICO) situation is encountered, it is too late to use ultrasound as this will waste critical time. In a patient with a high-risk airway, identifying the CTM with ultrasound before a CICO situation develops is a reasonable approach. We prefer the longitudinal string-of-pearls (SOP) technique, but the transverse thyroid-air-cricoid-air (TACA) can also be used [14]. With either technique, mark the CTM with the patient positioned how the cricothyrotomy will be performed (ie, head in extension unless concern for cervical spine injury) since the larynx is fairly mobile and can shift considerably with movement of the head and neck or change in angle of the head of the bed [15].

The following steps summarize the SOP technique for POCUS identification of the CTM (which can also be found in this video) [16,17]:

●Position the patient supine with the head in extension, if possible.

●Palpate the sternal notch and place the linear transducer transversely (with the marker towards the operator) just cephalad to it, thus visualizing the trachea.

●Slide the transducer towards the operator so that the non-marker side is overlying the midline of the trachea and only half of the tracheal ring is visualized.

●Maintain the non-marker side of the transducer over the mid-trachea while rotating the marker side 90 degrees cephalad into the sagittal plane, thus visualizing a row of hypoechoic ovals (anterior tracheal rings) just superficial to a white hyperechoic line (air-tissue interface).

●Slide the transducer cephalad in the midline until a larger and longer hypoechoic oval (cricoid cartilage) is visualized.

●Mark the space with a pen just cephalad to the cricoid cartilage. This represents the location of the CTM. If the transducer is slid further cephalad, another hypoechoic oval (thyroid cartilage) can be visualized, a needle can be slid between the transducer and the skin, thus casting a hypoechoic shadow over the CTM, which can then be marked with a pen after the transducer is removed.

Several studies in cadavers and volunteers suggest that, when used by experienced practitioners, ultrasound is a rapid and accurate means of identifying the CTM [18-24]. Ultrasound has also been used to guide tracheostomy. (See "Tracheostomy in adults: Techniques and intraoperative complications", section on 'Anatomic location'.)

PREPARATION

Patient counseling and informed consent — The emergency conditions under which this procedure is performed generally preclude the discussion of risks, benefits, and complications with the patient or family. Ideally, these discussions are held in patients with predicted difficult airways before airway management is initiated.

Equipment — Successful performance of a cricothyrotomy depends on familiarity with the necessary equipment. Ideally, the cricothyrotomy equipment tray should be simple (picture 1), in contrast to the typical tracheostomy tray, which may contain dozens of instruments. If not using a commercial cricothyrotomy kit (eg, Cook Melker kit, Quicktrach II), which contain all essential equipment, only a few instruments are required depending on which technique is performed:

●Scalpel – Preferred sizes include numbers 10 and 20 blades. However, in an emergency, any available blade size can be used. Use the same blade for both the skin incision and the cricothyroid membrane (CTM) incision.

●Tracheal tube – Either a cuffed tracheostomy tube (preferred) or tracheal tube.

•Cuffed tracheostomy tube – A number 4 Shiley tracheostomy tube (inner diameter of 5 mm and outer diameter of 9.4 mm) is preferred for most adults, as larger ones may be difficult to pass through the CTM. A standard tracheostomy tube kit often includes a tube with an inner cannula as well as a solid obturator (picture 2). The obturator facilities tracheal tube placement; it should be inserted in the tracheostomy tube prior to the procedure and replaced with the inner cannula after the tube is placed.

The outer diameter of the tube determines whether the tube will fit properly. There is significant product variability depending on the manufacturer and type of tracheostomy tube. A smaller diameter tube increases difficulty ventilating and is more easily obstructed by secretions.

•Modified tracheal tube – If a tracheostomy tube is not available, use a standard tracheal tube. We suggest using a size 6.0 tracheal tube. The proximal portion of the tube can be cut off just before the point of entry of the pilot balloon tubing. This helps shorten the length of the tube to minimize the risk of endobronchial placement or accidental dislodgement. After the tube is cut, the 15 mm adapter must be removed from top part of the tube and placed onto the remaining shorter tube.

Eventually, the tracheal tube can be exchanged for a tracheostomy tube over a bougie. This should be deferred until the patient is stabilized and appropriate help is available since the airway can be lost during the exchange. The design of the tracheostomy tube makes it more secure and less likely to move in the airway.

Tracheal tubes are numbered based on their internal diameter (6.0 tube has an internal diameter of 6 mm), but the outer diameter varies somewhat by manufacturer [25]. The outer diameter of a 6.0 tracheal tube generally ranges from 8 to 9 mm.

●Tracheal tube introducer ("bougie") – This is needed if performing scalpel-finger-bougie or modified rapid four-step techniques.

●Tracheal hook – This is needed if performing the traditional open or rapid four-step techniques. The hook's tip is sharp and can puncture the balloon on the tracheal tube, glove, or skin.

●Tracheal dilator (Trousseau dilator) – This is needed if performing the traditional open technique to widen the opening through the CTM [26]. Unlike most surgical instruments (eg, scissors, needle drivers), the dilator is opened by squeezing the handles together.

●Suction catheter (eg, DuCanto, Yankauer), tubing, and canister – Check that all connections are tight, and suction is adequate. We prefer the DuCanto suction catheter for emergency airway management because it has a larger bore and evacuates fluids much faster compared with the Yankauer catheter. A simulation study found that the DuCanto catheter had higher suction rates compared with the Yankauer catheter for all fluids of varying viscosities; the relative effect was greatest for those with high viscosity (211 versus 164 ml over 15 seconds for pudding-like consistency fluid) [27].

●10-mL syringe – Used to test the balloon on the tracheal tube for leaks and to inflate the cuff once the tube is inserted.

●Cloth tie (umbilical tape) – A cloth tie (included with the tracheostomy kit) is used to secure the tube by making a circumferential tie around the neck. If a cloth tie is not available, the tube can be secured with sutures to the skin similar to a tube thoracostomy.

Standard precautions against infection — Use standard precautions to protect against blood and body fluid exposure. This includes gloves, face mask, protective eyewear, gown, and shoe covers. Do not break, bend, or recap needles used in the procedure.

Patient positioning (with or without potential cervical spine injury) — Position the patient supine on the stretcher, which can be in reverse Trendelenburg to raise the larynx above the level of the stomach and minimize the risk of passive regurgitation and aspiration. In the absence of a known or suspected cervical spine injury, the head should be extended to help maximize neck exposure. In a trauma patient with potential or known cervical spine injury, the patient's head should be in the neutral position, and efforts should be made to limit cervical spine movement. However, establishing an airway is the priority and cricothyrotomy is unlikely to cause spinal cord injury.

Evidence is limited, but no case of neurologic deterioration or exacerbation of injury has been reported following cricothyrotomy in trauma patients [28]. A cadaver model suggests that cricothyrotomy does not move the cervical spine enough to result in neurologic injury. Even though a safe degree of movement is undetermined, studies report a low risk of neurologic deterioration with less than 3 mm of anterior-posterior (AP) displacement [29-32]. A study of traditional open cricothyrotomy in a cadaver model of an unstable injury at the level of the fifth cervical vertebra found only 1 to 2 mm of AP displacement and less than 1 mm of axial compression [33].

Rescue oxygenation — While assembling the equipment for the procedure, ask an assistant to administer high-flow oxygen, preferably by placing an extraglottic airway device (eg, laryngeal mask airway) or via bag-valve mask. Positive-pressure ventilation should be briefly paused once the CTM is incised to avoid blowing a mist of blood into the face of the proceduralist. (See "Extraglottic devices for emergency airway management in adults" and "Rapid sequence intubation in adults for emergency medicine and critical care", section on 'Preoxygenation'.)

Analgesia and sedation — During the course of a failed airway situation, ensure that the patient has received full neuromuscular blockade with appropriate sedation to facilitate non-surgical means of oxygenation and ventilation, which will also help facilitate the cricothyrotomy [3]. (See "Rapid sequence intubation in adults for emergency medicine and critical care", section on 'Paralysis with induction'.)

In the rare circumstance of a non-paralyzed patient with agitation who is in need of a cricothyrotomy, ketamine 1 to 2 mg/kg slowly administered intravenously may facilitate the procedure. In the rare circumstance of a conscious patient, anesthetize the skin, subcutaneous tissues, and the CTM with a local anesthetic such as lidocaine (preferably with epinephrine).

Skin preparation — If time permits, prepare the skin of the anterior neck with an antiseptic solution (eg, povidone-iodine).

Monitoring — Monitor heart rate and rhythm, blood pressure, respiratory rate, oxygen saturation, and end-tidal carbon dioxide (EtCO₂) throughout the procedure. Remove the patient's gown or sheet from the torso to observe the rise and fall of the chest with respiration.

PREFERRED TECHNIQUE: SCALPEL-FINGER-BOUGIE

In a patient who requires emergency cricothyrotomy, we suggest the scalpel-finger-bougie technique (also called the "bougie-assisted cricothyrotomy"). This technique is relatively simple, effective, and only requires readily available equipment (picture 3) [34,35]. Case reports and observational studies (including a surgical airway data-gathering application for smartphones) suggest a high success rate [36,37]. The evidence on time of completion is discussed below. (See 'Time to complete various techniques' below.)

The scalpel-finger-bougie technique is performed as follows:

●Step 1: Immobilize the larynx and palpate the cricothyroid membrane (CTM) – Stand at the patient's right side if you are right-handed, or at the patient's left side if you are left-handed. Immobilize the larynx with the nondominant hand and use the dominant hand to make the incision and pass the tube.

The procedure is largely tactile, so proper finger position is essential. Place the thumb and long finger of the non-dominant hand on either side of the thyroid cartilage to immobilize the larynx (picture 4). Palpate the laryngeal prominence at the midline of the cephalad rim of the thyroid cartilage with the index finger and then move caudally 1 to 2 cm until a small depression inferior to the thyroid cartilage is encountered. This is the CTM. Palpate the cricoid cartilage, which is at the inferior border of the CTM. Maintain manual control and immobilization of the larynx throughout the procedure to preserve the anatomic relationships.

●Step 2: Incise the skin vertically, repalpate the CTM, then incise the CTM horizontally – Make a generous 5 to 10 cm vertical incision in the skin overlying the CTM (picture 5). The midline skin incision avoids vascular structures located laterally. Additionally, the vertically orientated incision allows for easy extension superiorly or inferiorly should the initial location provide inadequate access to the CTM.

Next, insert an index finger into the incision (picture 6) and dissect bluntly to the CTM. A rigid cartilaginous structure surrounding the finger should be palpated. Remove the finger and make a stab incision horizontally through the CTM (picture 7).

●Step 3: Insert the bougie through the incision into the trachea – Withdraw the scalpel and immediately insert an index finger through the horizontal incision, dilate the opening in the CTM, and then use the volar pad of the index finger to direct the bougie caudally down the trachea (figure 4). Alternatively, do not remove the scalpel, but rather use it as a stent to open the incision and insert the bougie through the opening next to the scalpel directing it caudally down the trachea (picture 8 and picture 9).

Confirmation of tracheal placement is suggested by feeling "tracheal clicks" as the bougie passes over each tracheal ring, or by encountering resistance if the bougie reaches the carina or bronchus. Do not intentionally advance the bougie until resistance is felt, as excessive force may perforate the mainstem bronchus. Since emergency cricothyrotomy is performed rarely and during crisis situations, the clinician may not appreciate the "tracheal clicks."

●Step 4: Pass the tracheal tube over the bougie into the trachea – Pass a 6.0 mm tracheal tube over the bougie and advance it into the trachea while maintaining control of the bougie with the other hand (picture 10). Advance the tube about 6 to 8 cm, which would place it mid trachea in most adults (mean distance from the vocal cords to the carina is about 13 cm). Do not advance the tracheal tube too far, as it can easily pass into the right mainstem bronchus.

If a 6.0 mm tube will not fit through the CTM (due to variable size in adults), either copiously lubricate the bougie and pass a 5.5 mm tube, remove the bougie and pass a smaller tube (eg, 5.0 mm) directly through the incision into the trachea, or pass a pediatric bougie (if readily available) into the trachea and pass the smaller tube over the pediatric bougie. Most standard tracheal tubes 5.0 mm and smaller will not fit on a standard adult 15 French bougie, but a well lubricated 5.5 mm tube will pass over a 15 French relatively easily.

●Step 5: Remove the bougie and secure the tracheal tube – While stabilizing the tracheal tube in place with one hand, remove the bougie with the other (picture 11). Inflate the cuff of the tube with air from a 10-mL syringe. Inflate the balloon until the balloon indicator is full but not tense. Confirm tracheal placement with capnography or capnometry. Secure the tracheal tube with a cloth tie.

ALTERNATIVE TECHNIQUES

Rapid four-step technique — The rapid four-step technique can be done quickly and requires only a scalpel (preferably number 10 or 20 blade if available), tracheal hook, and cuffed tracheostomy tube [38]. It is performed with the following four steps in sequence:

●Step 1: Immobilize the larynx and palpate the cricothyroid membrane (CTM) – For this technique, stand at the head of the patient in the same position as when performing endotracheal intubation. Immobilize the larynx with the nondominant hand and palpate the CTM with the index finger (figure 5). Palpate the laryngeal prominence at the midline of the cephalad rim of the thyroid cartilage with the index finger and then move caudally 1 to 2 cm until palpating the small depression inferior to the thyroid cartilage, which is the CTM.

●Step 2: Make a single horizontal stab incision through the skin, subcutaneous tissue, and CTM – The incision is made with the scalpel using the dominant hand and should be approximately 3 cm (figure 6).

●Step 3: Place the hook – Prior to removal of the scalpel, place the hook and direct it inferiorly to engage the cricoid cartilage. Apply caudal traction to stabilize the larynx (figure 7). This is different from the traditional open technique, in which the tracheal hook is placed under the thyroid cartilage and an assistant is required to manage the hook.

●Step 4: Insert the tracheostomy tube into the trachea (figure 8) – Confirm tracheal placement with capnography or capnometry. Secure the tracheal tube with a cloth tie.

Modified four-step technique with introducer (bougie) — The rapid four-step technique can be modified by using a tracheal tube introducer (ie, "bougie"). This is done by inserting the introducer through the incision into the trachea following step 3 above and then sliding a tracheal tube over the introducer as described in steps 4 and 5 of the scalpel-finger-bougie technique. (See 'Preferred technique: Scalpel-finger-bougie' above.)

Seldinger technique — Cricothyrotomy can be performed using a Seldinger technique, typically with a commercial cricothyrotomy kit that contains all essential equipment [39]. As an example, the Cook Melker kit includes the following: a 6-mL syringe, an 18-gauge needle with overlying angiocatheter (some kits also have a needle without angiocatheter (picture 12)), a guide wire, a tissue dilator, a modified airway catheter (picture 13), and tracheostomy tape.

The procedure described here is based upon the Melker kit (with angiocatheter), which involves a guidewire. Perform the procedure as follows:

●Step 1: Check equipment, immobilize the larynx, and palpate the cricothyroid membrane (CTM) – Check that all equipment is present and functioning. Insert the dilator into the airway catheter. Palpate the CTM with the index finger of the nondominant hand while immobilizing the larynx with the thumb and middle finger (figure 5).

●Step 2: Insert the needle with overlying angiocatheter – Attach the introducer needle to the syringe and draw up 2 to 3 ml of saline. Insert the needle carefully into the CTM at a 45-degree angle with the needle oriented caudad and then apply a small amount of negative pressure on the syringe (figure 9). Be careful not to insert it too far as this may damage the posterior wall of the trachea. The appearance of air bubbles in the saline in the syringe during aspiration helps to identify when entering the trachea. If saline was not drawn into the syringe, the free flow of air and lack of resistance during aspiration indicates the needle is in the airway.

●Step 3: Insert the guidewire through angiocatheter – Remove the syringe and then remove the needle, leaving the angiocatheter in place, with its distal tip in the trachea. Thread the guidewire through the angiocatheter into the trachea (figure 10). Remove the angiocatheter, sliding it over the guidewire. The needle in the angiocatheter is smaller than the supplied needle without the angiocatheter; the wire will not go through the needle/angiocatheter combination until the needle is withdrawn.

●Step 4: Make a vertical incision through the skin and subcutaneous tissue – At the entrance point of the guidewire, make a 1 to 2 cm incision through the skin and subcutaneous tissue with a scalpel (figure 11).

●Step 5: Insert the airway catheter over the guidewire – Thread the airway catheter with the dilator inside it over the guidewire and advance it through the skin incision (figure 12). Following the curve of the dilator, advance the dilator-catheter unit through the subcutaneous soft tissue and into the trachea until the cuff of the catheter is flush against the skin of the neck. A slight twisting motion may be needed.

●Step 6: Remove the dilator and guidewire – Remove the tissue dilator and guidewire as a unit, leaving the airway catheter in the trachea (figure 13).

●Step 7: Secure airway catheter – Confirm tracheal placement with capnography or capnometry. Secure the airway catheter to the neck with the tracheostomy tape provided in the kit or other appropriate means.

Traditional open technique — The traditional open technique requires a scalpel (preferably number 10 or 20 blade if available), tracheal hook, tracheal dilator (Trousseau dilator), cuffed tracheostomy tube, and an assistant to hold the tracheal hook. It is performed in the following steps:

●Step 1: Immobilize the larynx and palpate the cricothyroid membrane (CTM) (figure 5) – Stand at the patient's right side if you are right-handed, or at the patient's left side if you are left-handed. Immobilize the larynx with the non-dominant hand and perform the procedure with the dominant hand.

The procedure is largely tactile, so proper finger position is essential. Place the thumb and long finger of the nondominant hand on either side of the thyroid cartilage to immobilize the larynx (picture 4). Palpate the laryngeal prominence at the midline of the cephalad rim of the thyroid cartilage with the index finger and then move caudally 1 to 2 cm until a small depression inferior to the thyroid cartilage is encountered. This is the CTM. Palpate the cricoid cartilage, which is at the inferior border of the CTM. Maintain manual control and immobilization of the larynx throughout the procedure to preserve the anatomic relationships.

Proper stabilization and continuous palpation of the immobilized larynx serves as the foundation for the procedure, from which all other anatomic relationships are established. While immobilizing the larynx, palpate the CTM and complete the entire procedure by digital palpation.

●Step 2: Incise the skin vertically (figure 14) – Make a generous 5 to 10 cm midline vertical incision through the skin overlying the membrane. The vertical orientation allows the incision to be extended superiorly or inferiorly should the initial provide inadequate access to the CTM, and midline placement avoids the lateral vessels.

●Step 3: Incise the CTM horizontally (figure 15) – Make a 2 cm horizontal incision in the CTM while angling the scalpel in a caudad direction, but do not use excessive force, which can injure the posterior wall of the trachea (the posterior portion of the cricoid ring is broad and helps to prevent the incision going through the posterior wall into the esophagus). The scalpel is angled caudad to avoid injuring the vocal cords, which are located only 0.5 to 2 cm cephalad to the CTM and are only partially protected by the thyroid cartilage [40]. Be careful not to incise or fracture the thyroid or cricoid cartilages.

Keep the tip of the index finger of the nondominant hand in the entry to the CTM incision so as not to lose the opening. Continue to immobilize the larynx firmly, maintaining a triangle formed by the thumb and middle finger on opposite sides of the larynx and the index finger in the incision in the CTM. It is crucial not to let go at this point because there is often significant bleeding that obscures the view of the membrane.

If the larynx cannot be stabilized because of obesity, edema, trauma, aberrant anatomy, or other reasons, the scalpel can be left in the incision, so the opening is not lost until the tracheal hook is placed. In this case, be careful not to injure the back wall of the trachea with the scalpel.

●Step 4: Insert the tracheal hook (figure 16) – Place the tracheal hook under the thyroid cartilage and ask an assistant to provide traction anteriorly and cephalad.

●Step 5: Enlarge the incision vertically with the tracheal dilator (figure 17) – Insert the tracheal (Trousseau) dilator into the CTM incision (perpendicular to the trachea such that the jaws will open vertically) and squeeze the handles to open its jaws to enlarge the incision. The membrane is naturally wider in the horizontal direction, which makes the vertical direction the most important to dilate. Overcome the resistance from the thyroid cartilage as it retracts downward and the cricoid cartilage as it retracts upward against the dilator. Leave the dilator in until the tube is placed; the thyroid and cricoid cartilages will spring back into place if the dilator is removed.

●Step 6: Insert the tracheostomy tube (figure 18) – Rotate the dilator 90 degrees so that the handles are pointing towards the patient's feet and insert the tube between the jaws of the tracheal dilator (without damaging the tube's balloon). If the dilator remains in its original perpendicular orientation, its inferior blade will prevent the tube from passing into the trachea. Once past the blades, advance the tube into the trachea. Remove the tracheal hook and dilator but be careful not to puncture the balloon of the tube.

●Step 7: Remove the obturator (if one was included with the tracheostomy tube) (figure 19) – This is the solid object with a rounded tip that facilitates tracheal tube placement but needs to be removed for patency of the tracheostomy tube.

●Step 8: Insert the inner cannula (if one was included with the tracheostomy tube) and inflate the balloon (figure 20) – Inflate the cuff of the tube with air from a 10-mL syringe. Inflate the balloon carefully until the balloon indicator is full but not tense; overinflation increases the risk of pressure-related injury to the tracheal mucosa. Confirm tracheal placement with capnography or capnometry.

●Step 9: Secure tracheal tube (figure 21) – Secure the tube with a circumferential cloth tie around the neck.

Percutaneous with prefabricated devices — We do not prefer commercially available percutaneous trocar-type devices. These consist of a catheter over a large-bore needle and are designed to be rapidly inserted as a single unit without the need for a surgical incision. Some versions (eg, Quicktrach II) include a protective blocker on the needle intended to reduce the risk of perforating the posterior airway. Clinicians who choose to use one of these prefabricated devices should be familiar with the equipment and technique and practice the procedure in a non-clinical setting on a routine basis. A step-by-step discussion of each individual device is beyond the scope of this topic.

TIME TO COMPLETE VARIOUS TECHNIQUES — Studies suggest that clinicians can perform cricothyrotomy reasonably quickly using the traditional open technique, but that the rapid four-step technique or the scalpel-finger-bougie technique may be faster. However, evidence is limited by lack of clinical trials, which are difficult to perform since this is an infrequent, unplanned, and time-dependent procedure. Available studies consist mostly of cadaver and animal models and report disparate findings. The time to completion and ease of performing cricothyrotomy ultimately depend upon the technique, patient, setting, and the training and experience of the clinician.

●Traditional open technique – A cadaver study found that experienced physicians needed a median of 73 seconds (range 53 to 255 seconds), while inexperienced clinicians (including medical students) required a median of 180 seconds (range 75 to 280 seconds) to complete a cricothyrotomy using the traditional open technique [41]. Another cadaver study found that paramedic students completed a traditional open cricothyrotomy in an average of 46 seconds (range 29 to 63 seconds) [42].

●Rapid four-step technique – A cadaver study found that inexperienced physicians performed the rapid four-step technique faster than the traditional open technique (mean time of 43 versus 134 seconds) and both techniques were 88 percent successful [43].

●Modified rapid four-step technique – A sheep model study found that inexperienced physicians performed the modified rapid four-step technique faster than the traditional open technique (median time 67 versus 149 seconds) [44]. Both techniques had similar success rates, but the modified rapid four-step technique was considered easier to perform.

●Scalpel-finger-bougie technique – A sheep model found that inexperienced physicians and medical students completed the scalpel-finger-bougie technique faster than the traditional open technique (median time 67 versus 147 seconds) and rated it easier to perform [44].

●Seldinger technique – Studies comparing the Seldinger technique with the traditional open technique have found conflicting results. A cadaver study found that emergency physicians achieved tracheal puncture and first ventilation faster with the Seldinger technique (precurved uncuffed catheter over guidewire) compared with the traditional open technique (mean time 99 versus 119 seconds and 109 versus 137 seconds, respectively) [39]. A porcine model study found that physicians performed the Seldinger technique (preloaded catheter/dilator over guidewire) faster if a skin and subcutaneous vertical incision preceded the needle placement-guidewire insertion (median time 53 versus 90 seconds) [45].

Other cadaver studies have found the Seldinger technique to have a similar insertion time compared with the traditional open technique, but still be effective with a low complication rate [46,47]. However, a cadaver study found medical students performed the Seldinger guidewire technique slower, less successfully, and with more complications compared with the traditional open technique [48].

●Prefabricated percutaneous devices – Studies have found similar success rates and times to insertion with these devices compared with other cricothyrotomy techniques [49,50]. However, evidence is limited, and most studies involve mannequin or animal models.

COMPLICATIONS

●Early complications – These include the following [51-54]:

•Inability to achieve airway access – The procedure must be attempted again, preferable with assistance from colleagues with experience in the procedure.

•Passage of the tube into an extratracheal location with subcutaneous emphysema – Once recognized, the tracheal tube must be removed, and the cricothyrotomy must be performed again. The development of massive subcutaneous air suggests the creation of a false tract from passage of the tube into an extratracheal location. This can occur if the tube was directed into the pre-tracheal or para-tracheal space by deflecting off the laryngeal cartilages after passed through the skin and subcutaneous tissue. Ideally, placement into a false passage should be recognized quickly by lack of appropriate capnography or capnometry before significant subcutaneous air develops.

•Bleeding – Bleeding occurs early and usually stops with packing of the wound and external compression [43]. If bleeding does not stop, operative control of the hemorrhage (by acute care surgeon or otolaryngologist) may be necessary.

•Damage to the larynx or perforation of the posterior trachea – These warrant consultation with an otolaryngologist.

A systematic review found that among 1219 patients who underwent emergency cricothyrotomy, the mean early complication rate was 13 percent [55]. The most frequent early complication was incorrect performance of the procedure resulting in damage to the cartilaginous structures or failure to access the airway. However, reported complication rates vary widely (between 0 and 54 percent) and depend upon the patient population, the clinical scenario, the clinician's level of training, and the procedure's setting (eg, emergency department, prehospital) [39,42,43,51-54,56-58].

●Cricoid cartilage injuries from tracheal hook – Limited evidence suggests that the rapid four-step technique is associated with more complications, specifically cricoid cartilage injuries, compared with other techniques. The cricoid cartilage, instead of the thyroid cartilage, is lifted during the rapid four-step technique. The tracheal hook is placed under the anterior portion, which is the weakest and thinnest part of the cricoid cartilage and the most vulnerable to injury [41]. (See 'Rapid four-step technique' above.)

In one cadaver study, the rapid four-step technique caused more major complications (eg, complete transection of the cricoid cartilage, posterior tracheal or esophageal perforation; 9 versus 3 percent) but had the same overall rate of complications (38 percent) compared with the traditional open technique [43]. Another cadaver study found a 17 percent complication rate with the rapid four-step technique but no complications with the traditional open technique [59]. Four of these injuries were to the cricoid cartilage and the remaining complication was a ruptured tracheal tube cuff.

●Long-term complications – These include subglottic stenosis and voice changes. Subglottic stenosis has been associated with prolonged intubation, underlying laryngeal disease, and younger age [60]. Other possible long-term complications include dysphagia and infection.

AFTER-PROCEDURE CARE — Use flexible connector tubing to attach the tracheal tube to the ventilator or bag valve device to avoid traction on the tracheal tube. Apply a dry tracheostomy dressing over the incision. Obtain a portable radiograph chest radiograph to check tube position. It is reasonable to prophylactically administer an antibiotic with skin and oropharyngeal flora coverage (eg, ampicillin-sulbactam). Ensure the patient has adequate sedation and analgesia and appropriate ventilator settings. (See "Mechanical ventilation of adults in the emergency department".)

Ensure that the tracheal tube does not become accidentally dislodged since finding the cricothyroid membrane and replacing the tube is not a simple procedure. An assistant should be assigned to stabilize the tube during any patient transfers. Suction the tracheal tube every two to three hours and also as needed for airway clearance. After-procedure care is similar to postoperative care for tracheostomy tubes. (See "Tracheostomy: Postoperative care, maintenance, and complications in adults", section on 'Postoperative care'.)

The admitting service will provide further care in consultation with surgery or otolaryngology since an emergency cricothyrotomy is an indication for urgent tracheostomy. (See "Tracheostomy: Rationale, indications, and contraindications".)

SKILL ACQUISITION AND MAINTENANCE (INFREQUENT PROCEDURE) — Clinicians responsible for airway management must be facile with at least one cricothyrotomy technique, thus skill acquisition and maintenance are vital. Because cricothyrotomy is a rarely performed but potentially life-saving procedure of last resort, we suggest that emergency clinicians review the anatomy and practice with the equipment needed for cricothyrotomy on a regular basis (eg, every three to six months) to maintain skill competency. Practice can be obtained with low fidelity airway models. A systematic review found that general procedural skill retention declines after 3 months and continues to decline after 6 and 12 months [61]. A study of skill retention in medical students following a simulation-based cricothyrotomy training found that skills decayed as early as by one month and that by six months, none of the participants had a passing performance [62].

We also suggest that clinicians maintain familiarity with the surface anatomy by regularly palpating the structures of the anterior neck when examining patients. Identifying the cricothyroid membrane requires regular practice and lack of familiarity can make it difficult to find quickly, particularly during an airway emergency. (See 'Surface anatomy of the anterior airway' above.)

Cricothyrotomy is infrequently performed, and rates vary among different providers and settings. The National Emergency Airway Registry (NEAR) study found that, of the 17,583 adult intubations performed in emergency departments over a 10-year period, 0.14 percent (about 25 patients) received a primary surgical airway and 0.31 percent (about 55 patients) received a rescue surgical airway [63]. An emergency medical services-based study reported that, of the 57,209 patients requiring advanced airway management in the prehospital setting, 0.5 percent (286 patients) underwent cricothyrotomy [64].

SUMMARY AND RECOMMENDATIONS

●General considerations for patient selection – Cricothyrotomy is indicated when a failed airway has occurred and a "can’t intubate, can’t oxygenate" (CICO) situation develops. Occasionally, a cricothyrotomy is performed as a primary technique when other techniques are felt unlikely to be successful or too risky. Placing an extraglottic airway device (eg, laryngeal mask airway) may be attempted as a rescue maneuver or as a bridge to provide ventilation while making preparations for cricothyrotomy. (See 'General considerations in failed airway scenario' above.)

●Contraindications – There are no absolute contraindications to emergency cricothyrotomy in adults, but it should not be performed in children <10 years old. Relative contraindications include complete transection of the trachea and laryngotracheal disruption with retraction of the distal trachea into the mediastinum. (See 'Contraindications and precautions' above.)

●Anatomy – The boundaries of the cricothyroid membrane (CTM) are the thyroid cartilage superiorly, the cricoid cartilage inferiorly, and the articulation of the inferior edge of the thyroid cartilage and the superior edge of the cricoid ring laterally, which forms a rigid circular opening (figure 1 and figure 2). Emergency cricothyrotomy is guided by palpation rather than direct visualization because following the initial incision, the surgical field is usually too bloody to see the relevant anatomy. (See 'Clinical anatomy' above.)

●Preferred technique – In a patient who requires emergency cricothyrotomy, we suggest the scalpel-finger-bougie technique (also called the "bougie-assisted cricothyrotomy") (Grade 2C). This technique has a high success rate, a minimal number of steps, can be rapidly executed, and will work in all adult patients (including those with impalpable anatomy). It requires equipment that is rapidly and always available, including a scalpel, tracheal tube introducer ("bougie"), and tracheal tube (picture 3). It is performed with the following steps (see 'Preferred technique: Scalpel-finger-bougie' above):

•Immobilize the larynx and palpate the CTM, which is the small depression 1 to 2 cm caudal to the thyroid cartilage (picture 4).

•Incise the skin vertically (picture 5), insert an index finger into the incision (picture 6) and dissect bluntly to the CTM, and remove the finger and make a stab incision horizontally through the CTM (picture 7).

•Withdraw the scalpel and immediately insert an index finger through the horizontal incision, dilate the opening in the CTM, and then use the volar pad of the index finger to direct the bougie caudally down the trachea (figure 4).

•Pass a 6.0 mm tracheal tube over the bougie and advance it into the trachea (picture 10).

•While securing the tracheal tube in place with one hand, remove the bougie with the other (picture 11).

●Alternative techniques

•Traditional open technique (see 'Traditional open technique' above)

•Rapid four-step technique (see 'Rapid four-step technique' above)

•Modified rapid four-step (using tracheal tube introducer) technique (see 'Modified four-step technique with introducer (bougie)' above)

•Seldinger technique (see 'Seldinger technique' above)

•Percutaneous technique using a prefabricated device (see 'Percutaneous with prefabricated devices' above)

●Complications – In addition to not accessing the airway, other early complications include laceration of the thyroid cartilage, cricoid cartilage, or tracheal rings; perforation of the posterior trachea; unintentional tracheostomy; and passage of the tube into an extratracheal location (subcutaneous air that develops with ventilation is a warning). Bleeding occurs early, is usually not severe, and can be controlled by packing the site with gauze. (See 'Complications' above.)

●After-procedure care – This includes confirming tracheal placement with capnography or capnometry and chest radiograph, securing the tube with cloth tie, attaching to a ventilator with flexible connector tubing, providing sedation, and periodic tracheal tube suctioning. (See 'After-procedure care' above.)

●Skill acquisition and maintenance – This is an infrequently performed but potentially life-saving procedure of last resort in the patient with a failed airway. We suggest that all clinicians responsible for airway management review the anatomy, choose a preferred technique, and practice with the equipment needed for cricothyrotomy on a regular basis. Practice can be obtained with low fidelity airway models. (See 'Skill acquisition and maintenance (infrequent procedure)' above.)

ACKNOWLEDGMENT — The UpToDate editorial staff acknowledges Aaron E Bair, MD, MSc, FAAEM, FACEP, now deceased, who contributed to earlier versions of this topic review.