Airway Management Prepared by Dr. Mahmoud Abdel-Khalek.
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Transcript of Airway Management Prepared by Dr. Mahmoud Abdel-Khalek.
Airway Management
Prepared byDr. Mahmoud Abdel-Khalek
Introduction
In order to ensure adequate oxygenation and ventilation throughout the insults of anesthesia and surgery, the anesthesiologist must take active measures to maintain the patency of the airway as well as ensuring its protection from aspiration
Airway Anatomy
The airways can be divided into 2 parts
namely:
The upper airway.
The lower airway.
Anatomy of the Upper Airway
Upper airway– Airway structures
above the vocal chords
Larynx– Divides upper and
lower airways
Pharynx– Extends from the
nose and mouth to the esophagus and trachea Nasopharynx Oropharynx Laryngopharynx
Upper and Lower Airway
Upper Airway
Anatomy of the Upper Airway
Oral Cavity
Adenoids and tonsils may become swollen and infected may cause upper airway obstruction
Larynx
Marks where the upper airway ends and lower airway begins
Thyroid cartilage– Formed by two plates
that form the laryngeal prominence (Adam’s apple)
Cricoid cartilage is the first ring of the trachea
Cricothyroid membrane: ligament between the thyroid and cricoid cartilage site for emergency surgical and nonsurgical access to the airway (cricothyrotomy)
Larynx Glottis: Space between the
vocal cords Vallecula
– Pocket between base of tongue and epiglottis
– Important landmark for ET intubation
Arytenoid cartilages– Posterior attachment of the
vocal cords– Valuable guides for ET
intubation Laryngospasm: spasmodic
closure of the vocal cords seals off the airway
Trachea
Begins below the cricoid cartilage About 12cm length in adults 1st tracheal ring anterior to C6 Supported by 17-18 C-shaped cartilages (open
posteriorly; membranous aspect overlies esophagus
Trachea ends at level of carina at T5 Divides into right and left mainstem bronchi Right mainstem bronchus larger in diameter and
deviates at less acute angle than left (therefore aspiration or endobronchial intubation usu. to right side)
Routine airway management
Routine airway management associated with general anesthesia consists of: Airway assessment Preparation and equipment check Patient positioning Preoxygenation Bag and mask ventilation (BMV) Intubation (if indicated) Confirmation of endotracheal tube placement Intraoperative management and troubleshooting Extubation
Airway Assessment: Mouth opening
An incisor distance of 3 cm or greater is desirable in an adult
Thyromental Distance: Thyromental distance
Thyromental distance: the distance between the mentum and the superior thyroid notch
A distance greater than 3 fingerbreadths is desirable
Airway Assessment: Mallampati Classification
Examines the size of the tongue in relation to the oral cavity
Large sized tongue obstructs the view of the pharyngeal structures and may add difficulty to intubation
Conditions Associated with Difficult Intubation
Preparation and equipment check Preparation is mandatory for all
airway management scenarios The following equipment is routinely
needed in airway management situations– An oxygen source– BMV capability– Laryngoscopes (direct and video)– Several endotracheal tubes of
different sizes– Other (not endotracheal tube)
airway devices (e.g., oral, nasal airways)
– Suction– Oximetry and CO2 detection– Stethoscope– Tape– Blood pressure and ECG monitors– Intravenous access
Preparation
Laryngoscopes
Oral artificial airway sizes Sizes: 00-6 Correct size by
measuring from corner of mouth to bottom of earlobe
Adult oral airways typically come in small (80 mm [Guedel No. 3]), medium (90 mm [Guedel No. 4]), and large (100 mm [Guedel No. 5]) sizes.
Endotracheal tubes
The face mask
Patient Positioning
Relative alignment of the oral andpharyngeal axes is achieved by having the patient in the “sniffing” position
Preoxygenation When possible, preoxygenation with face mask oxygen
should precede all airway management interventions Oxygen is delivered by mask for several minutes prior to
anesthetic induction. The FRC, the patient’s oxygen reserve, is purged of
nitrogen. Up to 90% of the normal FRC of 2 L following
preoxygenation is filled with O2
Considering the normal oxygen demand of 200–250 mL/min, the preoxygenated patient may have a 5–8 min oxygen reserve.
Thus improving safety by allowing more time before desaturation in if ventilation following anesthetic induction is delayed.
Conditions that increase oxygen demand (e.g., sepsis, pregnancy) and decrease FRC (e.g. morbid obesity, pregnancy) reduce the apneic period before desaturation ensues.
The use of face mask
In current practice the face mask is only used 1. In preoxygenation
before tracheal intubation or insertion of the laryngeal mask
2. During short non-invasive procedures, e.g. Orthopedic manipulations and dental anaesthesia
Technique of face mask
selection of the correct fit is important to provide a gas-tight seal
For children, a mask with excessive dead space should be avoided (Rebreathing)
The mandible is held ‘into’ the mask by the anesthetist and forward to prevent obstruction of the airway by the tongue
The importance of observation of the airway during mask anesthesia cannot be overemphasized
Maintenance of the airway may be assisted further by the use of an oropharyngeal (Guedel) airway in anesthetized patients
Technique….
Disadvantages
It “ties up” the anesthesiologist’s hands It does not protect against aspiration or
laryngospasm (closure of the cords in response to noxious stimuli at light planes of anesthesia)
Upper airway obstruction may occur, particularly in obese patients or patients with very large tongues
Laryngeal Mask Airway (LMA)
LMA consists of a wide bore tube whose proximal end connects to a breathing circuit with a standard 15-mm connector, and whose distal end is attached to an elliptical cuff that can be inflated through a pilot tube.
The deflated cuff is lubricated and inserted blindly into the hypopharynx so that, once inflated, the cuff forms a low-pressure seal around the entrance to the larynx.
This requires anesthetic depth and muscle relaxation slightly greater than that required for the insertion of an oral airway.
Advantages and disadvantages
Indications To provide a clear airway without the need for the
anesthetist’s hands to support a face mask. To avoid the use of tracheal intubation during
spontaneous ventilation. In a case of unanticipated difficult intubation
Contraindications ‘Full stomach’ A patient in whom the risk of regurgitation of
gastric contents into the esophagus is increased (e.g. hiatus hernia).
Oral operations as it may prevent surgical access
Size selection& Techniqueq
Technique of LMA insertion
Tracheal Intubation
ET tube
Most commonly made of PVC The shape and rigidity of TT’s can be altered by inserting a
stylet The patient end of the tube is beveled to aid visualization and
insertion through the vocal cords (the Murphy eye) to decrease the risk of occlusion Most adult TT’s have a cuff inflation system consisting of a
valve, pilot balloon, inflating tube, and cuff
Indications Provision of a clear airway, e.g. anticipated
difficulty in using mask anesthesia in the edentulous patient
An ‘unusual’ and prolonged position, e.g. prone or sitting. A reinforced non-kinking tube may be necessary.
Operations on the head and neck, e.g. ENT, dental A nasotracheal tube may be required.
Protection of the respiratory tract against aspiration e.g. from blood during upper respiratory tract or oral surgery and from inhalation of gastric contents in emergency surgery or patients with oesophageal obstruction.
During anesthesia using IPPV and muscle relaxants
To facilitate suction of the respiratory tract During thoracic operations
Contraindications for Intubation
Patients with an intact gag reflex Patients likely to react with laryngospasm to an
intubation attempt. e.g. Children with epiglottitis Basilar skull fracture – avoid naso-tracheal
intubation and nasogastric/pharyngeal tube.
Technique Position the patient
supine, open the airway with a head-tilt chin-lift maneuver.(Suspected spinal injury, attempt naso-tracheal intubation, spine in neutral position.).
Open mouth by separating the lips and pulling on upper jaw with the index finger.
Hold laryngoscope in left hand, insert scope into mouth with blade directed to right tonsil.
Technique
Once right tonsil is reached, sweep the blade to the midline keeping the tongue on the left.
This brings the epiglottis into view.” DO NOT LOOSE SIGHT OF IT!”
Advance the blade until it reaches the angle between the base of the tongue and epiglottis.( vallecular space)
Lift the laryngoscope upwards and away from the nose – towards the chest. This should bring the vocal cords into view. It may be necessary for a colleague to press on the trachea to improve the view of the larynx.
Technique Place the ETT in the right hand. Keep the
concavity of the tube facing the right side of the mouth.
Insert the tube watching it enter through the cords Insert the tube just so the cuff has passed the cords and then inflate the cuff.
Listed for air entry at both apices and both axillae to ensure correct placement using a stethoscope.
Technique
Confirmation of Tube Placement
End Tidal Carbon Dioxide Monitor
Stethoscope
Complications
Nasotracheal Intubation
Nasotracheal intubationAdvantages: Comfortable for prolong intubation in postoperative
period Suitable for oral surgery : tonsillectomy , mandible
surgery For blind nasal intubation Can take oral feeding Resist for kinking and difficult to accidental
extubation
Disadvantages Trauma to nasal mucosa Risk for sinusitis following prolonged intubation Risk of bacteremia Smaller diameter than oral route
Contraindication for nasoendotracheal intubation
Fracture base of skull
Large adenoids
Coagulopathy
Nasal cavity obstruction
Retropharyngeal abscess
Thank You