Everything there is to know about an intubation scope
The intubation scope is an airway medical device used for endotracheal intubation in the management of various airway crisis. It provides the means for an indirect laryngoscopy in which the larynx is not viewed directly by the physician but with a digital aid. This digital aid could be fiberoptic (widely used in anesthesia) or one of the recently developed bronchoscopes. These are different from the metal laryngoscopes used for direct laryngoscopy. The use of a flexible intubation scope has been beneficial in situations where a direct laryngoscopy is dangerous, perplexing, or outright impossible. It is also preferred for conscious intubation
History of intubation and intubation devices
The earliest invasive airway management procedure recorded is tracheotomy. The procedure was described in the treatment of guinea-worm infection and first found on Egyptian tablets dated to around 3600BC. It was later seen in Eber’s Papyrus, which was written as far back as 1500BC. The Greeks made some discouraging remarks on tracheotomy. A notable one is the one made by the famous Hippocrates on the excessive risks associated with the procedure.
In Europe, tracheostomy was first described by Brassavola of Ferrara in 1546. Although tracheostomy became an established procedure in the 19th century, numerous efforts continue to discover a non-surgical procedure for airway management. Airway obstruction accompanying the diphtheria disease triggered the development of different techniques for intubation. Prominent proponents include Eugene Bouchet (1818-1891), William McEwen (1848-1924), Joseph O’Dwyer, and others. As tricky and faulty as their techniques may seem, they were of great help until the development of the diphtheria vaccine in the early 20th century. The first proper direct laryngoscopy was performed by Albert Kirsten in Berlin using his autoscope in 1895. This idea led to the development of laryngoscope devices in the 1940s, when we were introduced to Sir William McIntosh’s curved and Miller’s straight laryngoscope blades. The flexible intubation scope is the latest device widely used in airway management.
Indications to use
Since its development, the intubation scope has shown a higher success rate than other direct and indirect methods. A recent study shows a 51% success rate for direct intubation using McIntosh blade while that of the flexible scopes is over 90%.
The indications for using an intubation scope is nearly inexhaustible. They are used in the management technique for airway crisis, and they are now more commonly used for this procedure. Endotracheal intubation is used on patients (conscious or otherwise) in the Intensive Care Unit, emergency unit, etc. Patients requiring intubation typically have one or more of the following problems:
- Failure to keep the airway open
- Ventilation problems and this can make intubation difficult too
- Risk of respiratory failure
- Inability to prevent aspiration into the airway
- Insufficient oxygenation
A more detailed list of the indications for using the intubation scope is in the table below.
Hypoxemia or hypercarbia, critically ill patients
Inadequate oxygen circulation
Cardiac arrest in situations of hypotension or hypothermia
Tumor, infection, airway obstruction, paralysis of larynx, laryngospasm
Central nervous system and metabolic disorders
Diseases of the respiratory and axillary muscles that can cause respiratory failure and central apnea syndromes. Examples are Myasthenia gravis, polymyositis, Guillain-Barre, nerve injury, amyotrophic lateral sclerosis, acid-maltase insufficiency, electrolyte disturbances, and so on.
Reflex bradycardia, vasospasm, and laryngospasm
Intrathoracic and abdominal interventions require respiratory control and muscle relaxation
After anesthesia, any patient susceptible to the aspiration of stomach contents, blood, mucus, or secretion
Need for airway protection
Toxic epidermal necrolysis, Stevens-Johnson syndrome
Need for urgent aggressive sedation
To control recurrent attacks of contractions in status epilepticus, tetanus, and so on. It can also be for cerebral protection or prevention of postoperative rise in intracranial pressure
Head and neck surgery, especially when mask ventilation is not possible
There is, however, a need for a more concise list of emergency indications for intubation. Failure to identify an emergency need to use these flexible scopes often results in patient death.
- Respiratory failure or apnea
- Airway obstruction or disruption of airway reflex
- Inadequate ventilation or oxygenation
- Hemodynamically unstable patients
- Cardiopulmonary resuscitation
Complications of using intubation scope
There is no severe problem associated with the use of the intubation scope. The common complication of the procedure itself is hypoxemia because desaturation can occur. However, many techniques have been used for the preoxygenation process to prevent this complication.
No severe airway trauma has been reported due to the use of flexible scopes. Hence, bleeding has also been reported very rarely. Flexible intubation scopes show lesser use difficulty compared to direct laryngoscope. However, a novice may find a direct laryngoscope easier to use. In summary, flexible scopes have shown a lower risk of complications when compared to other alternatives.
The alternatives to flexible scopes include:
- Combined ventilation and intubation devices. Examples are intubating supraglottic airway device (SAD), intubating laryngeal mask airway (ILMA), and so on.
- Rigid or semi‐rigid stylets. They may be either lighted, such as the Trachlight, or optical, such as the Shikani Optical Stylet.
Specifications of tracheal intubation scopes
The specifications for the kinds of intubation scopes commercially available are discussed below.
- LF-V (Flexible tracheal laryngoscope) – a narrow 4.1 mm tip allows easy passage through single-lumen tubes of ≥ 5.5 mm and double-lumen tubes of ≥ 37 Fr.
- LG-GP (Flexible tracheal fiberscope) - a 1.5 mm channel causes an increased suction capability. The fiberscope’s narrow 4.1 mm outer diameter allows easier insertion. The scope is compatible with single-lumen tubes with an internal diameter as small as 5 mm, as well as double-lumen tubes ≥ 37 Fr.
- LF-P (Flexible tracheal fiberscope) - the LF-P is a small-diameter tracheal fiberscope which offers an ultrathin insertion tube applicable for use in patients with small airways. The breakthrough angulation capabilities of the device are about 120 degrees, which delivers high-quality optical performance.
- LF-TP (Flexible tracheal fiberscope) - a wide 2.6 mm suction channel increases the scope’s capability to suction highly viscous fluid. The outer diameter is 5.2 mm. If the internal diameter of a single-lumen tracheal tube is ≥ 6.0 mm, the LF-TP is compatible.
- LF-DP (Flexible tracheal fiberscope) – with a slim 3.1 mm diameter insertion tube, double-lumen endobronchial tubes can also be suited for insertion and position confirmation. Double-lumen tubes of ≥ 32 Fr are compatible with the scope.
How to use intubation scopes
It is quite easy to use flexible intubation scopes. There are only a few basic instructions to follow. The flexible scope is held in the left hand with the insertion cord in a straight position to maximize the turning capacity. Curves should not be allowed along the insertion cord, as it will cause the loss of the turning ability. The flexible scope is then placed into the patient’s airway through the nasal or oral route. The different tissues and organs along the airway can be viewed and assessed.
With the tracheal tube loaded onto the flexible scope, it can now be inserted into the airways to ventilate the lungs, allowing free movement of air into and out of the lungs. The tube forms an open passage in the upper airways. The endotracheal tube can also deliver anesthesia, facilitating the placement of the tube for surgical patients. Certain drugs cannot be given because the patient's clinical status cannot be ascertained, even in emergency cases.
The health practitioners allowed to intubate are physicians and special/advanced practice nurses. Specialist nurses, like nurse anesthetists, and nurses who work in the emergency department are also entitled to intubate. Finally, air, ambulance, and transport nurses are required to be able to perform the procedure.
The very notable brands of flexible Intubation scope are Olympus Medical® and Ambu®, a Scope™. They offer different kinds of flexible scopes, as detailed in the specifications above.
Prominent brands that make numerous kinds of intubation scopes and other similar devices are as follows:
- AircraB Medical Limited, Edinburgh, UK
- Verathon Medical Inc, Bothell, WA, USA
- Pentax AWS, Ambu A/S, Ballerup, Denmark)
- Laerdal Medical, Armonk, NY, USA
- Clarus Medical, LLC, Minneapolis, MN, USA
- Intavent Direct, Maidenhead, UK
- LMA North America Inc, San Diego, CA, USA
- Intavent Direct Maidenhead, UK
The importance and usefulness of flexible scopes cannot be overemphasized. This is more evident in the extent people were willing to go before the development of these modern techniques. Riskier and grossly invasive procedures were employed in the past. Intubation scopes help in ventilation and respiratory processes, which is a critical physiological occurrence. The vital organs in the body require an uninterrupted supply of oxygen. Failure to adequately respirate or ventilate is an emergency crisis that can quickly lead to death if not controlled. Viewing of the airways also facilitates the diagnosis of a ventilatory problem causing the crisis. The use of flexible fiberscopes in anesthesia cannot be overlooked. It is safe to conclude that intubation scopes will remain vital medical devices in both the near and distant future.