Airway Management

Article Author:
Usha Avva
Article Editor:
John Kiel
Updated:
1/4/2019 3:01:34 PM
PubMed Link:
Airway Management

Introduction

To be skillful at the airway management, the provider must have knowledge of the important anatomical, physiological, and pathological features related to the airway as well as knowledge of the various tools and methods that have been developed for this purpose. They also should know the differences between the adult, pediatric and neonatal airways and well versed with other difficult airways as these differences could impact on the safe and effective control of the airway.[0]

The four principals of airway management in ACLS (Advanced Cardiovascular Life Support) are

  1. Is the airway patent?
  2. Is the advanced airway indicated?
  3. Is the proper placement of airway devise confirmed?
  4. Is the tube secure and placement of the tube confirmed frequently?

Anatomy

The pediatric airway is narrower at the subglottic area, is cephalad and more anteriorly when compared to the adult airway which is narrower at the glottis. Children 12 years or younger have a smaller cricothyroid membrane and their larynx is compliant, funnel-shaped and rostral in position. The larger occiput combined with a shorter neck makes laryngoscopy relatively more difficult by providing obstacles to the alignment of the oral, laryngeal, and tracheal axes. It often requires a folded towel as a shoulder roll to achieve a neutral position of the neck and open the airway.[0]

The dimensions of the trachea depend on the age and sex of the child. Please see Table 1. There are different formulas to select the proper size of the ET tube.

  1. The Cole formula for uncuffed tubes: ID (internal diameter) in mm= (age in years)/4 + 4 (F)
  2. The Motoyama formula for cuffed ETTs in children aged 2 years or older: ID in mm = (age in years)/4 + 3.5 (EK)
  3. The Khine formula for cuffed ETTs in children younger than 2 years: ID in mm = (age in years)/4 + 3.0

Children aged 1 month to 6 years, ultrasound measurement of subglottic airway diameter better predicted appropriately sized endotracheal tube than traditional formulas using age and height. [0] Cuffed ET tubes are preferable to decrease the air leak, pressure necrosis in ventilated patients, as the incidence of laryngospasm is higher with uncuffed ET tubes. Glideascope is a recent adjuvant in the airway management that helps in proper visualization of the airway.[0] 

Table 1: Tracheal Dimensions ages 14-20 Years. [0] 

Indications

Indications for intervening to secure the airway include respiratory failure (hypoxic or hypercapnic), apnea, a reduced level of consciousness (sometimes stated as GCS less than or equal to 8), rapid change of mental status, airway injury or impending airway compromise, high risk for aspiration, or 'trauma to the box', which includes all penetrating injuries to the abdomen or chest cavity.

Contraindications

The only absolute contraindication to surgical cricothyroidotomy is the age of the child although the exact age at which they can safely perform a surgical cricothyrotomy is controversial and not well defined. Various sources list lower age limits ranging from 5 years to 12 years, and Pediatric Advanced Life Support (PALS) defines the pediatric airway as age 1-8 years. 

Equipment

Airway Position and Clearance

Upper airway obstruction relieved by head tilt, chin lift, or jaw thrust. In infants and children, a simple suctioning of the airway will help with the clearance. The bulb syringe or any other mechanical suction device can clear the airway.  When using a bulb syringe to suction an infant, it is important to suction the mouth before the nose to avoid aspiration. The first step is to depress the bulb syringe and then place it in the mouth and nose. Infants are prone to vagal stimulation and suctioning can lead to bradycardia.  Suction must not last for over 10 seconds.

Adjuvants to Upper Airway Obstruction

Oropharyngeal airway: One cannot use an oropharyngeal airway in patients with an intact gag reflux or oral trauma. Different sizes are available. They measure the oropharyngeal airway size from the lip to the angle of the jaw and is useful for patients with spontaneous respirations but needed help to keep their airway open.

Nasopharyngeal airway:  Is used in patients with an intact gag reflex, trismus or oral trauma which is an advantage over the nasopharyngeal airway. The important factor in sizing a nasopharyngeal airway (NPA) is not the width of the tube but rather the length of the subject. The average adult male needs a size 7 port and average female needs a size 6 port. A tall male requires size 8, and a tall female requires size 7.[0]

A study of 413 infants under 12 months found an association between subject height and nares-vocal cord distance. To place the NPA in infants, the insertion length must, therefore, be slightly less than the anthropometric measurement of nose tip-earlobe distance.[0]

Bag-mask Ventilation

A properly performed mask ventilation is the fundamental maneuver in airway management. Both in adults and pediatrics, there are one- and two-hand techniques. For neonatal airway one hand technique is enough.  One can relieve the upper airway obstruction encountered during simple mask ventilation by head tilt, chin lift, jaw thrust, and the application of continuous positive airway pressure. Bag-mask ventilation is also appropriate while preparing to intubate. 

Advanced Airway

Examples are supraglottic devices (laryngeal mask airway, laryngeal tube, esophageal-tracheal) and endotracheal tube.

Laryngeal mask airway: A relatively recent advancement is the development of the supra-glottic airway. Many devices exist. Two of the more popular supra-glottic devices, the classic laryngeal mask airway (LMA) and pro-seal LMA, have good data in the pediatric population to support their safety and efficacy. We recommended using a manometer to gauge the inflation pressure of the cuff of the LMA. Children with a recent upper respiratory infections has an increased incidence of respiratory complications with the use of LMA as compared to healthy children. In the pre-hospital setting, they often use supraglottic devices such as the king tube instead of an endotracheal tube because of the ease and speed with which they place it. This facilitates the rapid transportation to the hospital.

Esophageal-Tracheal tube and Endotracheal Intubation

This is one of the supraglottic airways now frequently used by many emergency medical personnel. They are popular because of their ease of administration.  They come in different sizes, but their routine use did not extend to the pediatric airway management.

Oxygen

Oxygen is a critical component of airway management. Nasal cannula, mask, high flow, bi-pap etc before the intubation can deliver the much-needed oxygen.

Bougie

Some physicians consider the bougie which is a long, semi rigid plastic device (a stylet without metal) as an adjunct or rescue device in difficult intubations or as a part of the primary intubation algorithm. 

Personnel

Ideally there should be at least two other staff members available to assist the primary physician who is performing the intubation with administration of medications, bagging the patient. The team include a respiratory therapist, resident, nurse, nursing tech, paramedic or advanced practice provider. 

Preparation

Rapid-sequence induction accompanied after pre-oxygenation with cricoid pressure and in-line cervical stabilization, followed by direct laryngoscopy (DL) is the safest and most effective approach.

The four D’s of the difficult airway is

  1. Distortion
  2. Disproportion
  3. Dysmobility
  4. Dentition

The location of the vallecula is vital for all healthcare workers who perform intubation. It is an important anatomical landmark during oral intubation of the trachea. To visualize the vallecula, place the blade of the Macintosh laryngoscope on to the vallecula and depress to see the glottis. Non-visualization of vallecula during intubation, increases the risk of esophageal intubation.  Introduce the ET tube only after visualization of the glottis.

Required equipment:

1. Laryngoscope

2. Carbon dioxide detectors

3. Continuous Waveform capnography

4. Medications: Sedatives and Paralytic agents for rapid sequence intubation (RSI)

5. Material to fix the tube in place

6. Chest X-ray

Following are the dosages of RSI medications:

Sedatives used for induction

  1. Etomidate: 0.3-0.4 mg/kg
  2. Fentanyl: 2-10 mcg/kg
  3. Midazolam: 0.1-0.3 mg/kg
  4. Propofol: 1-2.5 mg/kg
  5. Thiopental 3-5 mg/kg

Paralytic agents

  1. Succinylcholine: 1-2 mg/kg
  2. Rocuronium 0.6-1.2 mg/kg
  3. Vecuronium 0.15-0.25 mg/kg

Technique

Rapid-sequence induction accompanied after pre-oxygenation with cricoid pressure and in-line cervical stabilization, followed by laryngoscopy (direct or indirect), is the safest and most effective approach.

The gold standard for assessing placement of an ET is direct visualization with the help of a laryngoscope.  We use carbon dioxide detectors for confirmation of the endotracheal tube placement in the trachea.  The AHA (American Heart Association) recommends continuous waveform capnography besides clinical assessment as the most reliable method of confirming and monitoring correct placement of an ET tube. Bedside mobile ultrasound is another resource that some emergency departments have to confirm the position of the ET tube. Many physicians frequently use a chest x-ray to assess the placement of the ET tube. The optimum position of the ET tube is 2 centimeters above the carina. Most times, when blind endotracheal intubation takes place, the tube may go down the right main stem bronchus.  One could reposition the tube if the abnormal tube placement in seen in an X-ray.  They diagnose abnormal tube placement with absent breath sounds on the left chest, with low oxygen saturation. Once we secure the ETT properly, we monitor its placement continuously with waveform capnography and pulse oxygen monitor.

Pediatric Intensive care specialists prefer to use a cuffed endotracheal tube instead of an uncuffed endotracheal tube to prevent air-leak.

Airway Management in Traumatic Patients

Trauma is a leading cause of morbidity and mortality worldwide especially for people aged 15 to 50.  Trauma is the second-most common single cause of death, representing 8% of all deaths. The World Health Organization estimates that traumatic injuries from traffic accidents, drowning, poisoning, falls, burns, and violence kill over five million people worldwide annually, with millions more suffering from the consequences of injuries.

Rapid evacuation and transportation to a trauma center improve the outcome in severely injured patients. Prehospital intubation is controversial in the EMS literature and the medical director of an EMS service will dictate the clinical context in which he/she will allow a paramedic to intubate in the field.  The EMS service monitors and transports these patients quickly and safely to the nearest trauma facility.

Surgical Airway

The  age of the child is the only absolute contraindication to surgical cricothyroidotomy. The exact age at which they can safely perform a surgical cricothyrotomy is controversial and not well defined. Various sources list lower age limits ranging from 5 to 12 years, and Pediatric Advanced Life Support (PALS) defines the pediatric airway as age 1 to 8 years. 

Complications

Complications with intubation involve failure to secure the airway, esophageal intubation, hypoxic or hypercapnic respiratory failure leading to arrest,  injury to oropharyngeal or laryngeal airway including bleeding, soft tissue swelling, injury to vocal cords.

When intubating a patient who suffered injuries to the chest, pay attention to the complications that could arise after the intubation like tension pneumothorax or air leak from a bronchial injury. Patients with pneumothorax should have a chest tube before the intubation. In cases of bronchial injury, intubation can precipitate a massive air leak. Sometimes the physicians occlude a segment of the damaged lung with a bronchial blocker to avoid air escape.

Clinical Significance

Teaching points:

1. Knowing the differences between pediatric airway and adult airway

2. Knowing and selecting the correct airway management strategies.

3. Knowing the indications, technique and medications used in rapid sequence intubation

4. Knowing how to assess a difficult airway

5. Knowing the alternate techniques to achieve a definitive airway

6. Knowing the various adjuvants in the airway management

7. Knowing the airway management in special circumstances like penetrating trauma

8. Knowing the importance of training and practice in pediatric airway for prehospital personnel.

Enhancing Healthcare Team Outcomes

Team approach, good preparation, preoxygenation and recognition of difficult airway enhances the success of the airway management. Changing the plan once the provider recognizes the difficulty is prudent and safe. This decreases the failed intubation rates.

All the personnel involved should regularly sharpen their skills either in the field or in the simulation lab. Proper training of the personnel played a bigger role in improving the success rates of intubation, the decrease in mortality rate than the field of medicine they specialized in.[7] Evidence Level 3 

Emergency physicians use either length or weight based estimation to select the correct endotracheal tube for intubation.[0] Evidence Level 3

For difficult airways, the GlideScope laryngoscopy is better than the direct laryngoscope for the first pass success of the intubation.[9] Evidence Level 1



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      Contributed by Harless J, Ramaiah R, Bhananker SM. Pediatric airway management. Int J Crit Illn Inj Sci [serial online] 2014 [cited 2017 Dec 3];4:65-70. Available from: http://www.ijciis.org/text.asp?2014/4/1/65/128015