Airway evaluation and Management By :Dr. Adel Elshimy

Lecture Objectives Students at the end of the lecture will be able to :  Describe the applied anatomy of the airway.  Conduct a preoperative airway assessment.  Identify a potentially difficult airway.  Learn about management of airway obstruction.  Become familiar with airway equipment.  Understand issues around aspiration prophylaxis.  Become familiar with controlled ventilation.  Appreciate ways of monitoring of ventilation and oxygenation.

AIRWAY CONTROL Opening the Airway Jaw thrust Head tilt–chin lift

AIRWAY CONTROL Oropharyngeal Airway

Mask Ventilation Oral airway Oral airway Two-handed technique Two-handed technique

AIRWAY CONTROL Oropharyngeal Airway (cont.)

AIRWAY CONTROL Nasopharyngeal Airway (cont.)

OXYGENATION AND VENTILATION Bag-Valve-Mask (cont.) With oxygen reservoir

Esophageal-Tracheal Combitube A = esophageal obturator; ventilation into trachea through side openings = B C = tracheal tube; ventilation through open end if proximal end inserted in trachea D = pharyngeal cuff; inflated through catheter = E F = esophageal cuff; inflated through catheter = G H = teeth marker; blindly insert Combitube until marker is at level of teeth Distal End Proximal End B C D E F G H A

Usage

Indications of intubation Resuscitation (CPR) Resuscitation (CPR) Prevention of lung soiling Prevention of lung soiling Positive pressure ventilation (GA) Positive pressure ventilation (GA) Pulmonary toilet Pulmonary toilet Patent airway (coma or near coma) Patent airway (coma or near coma) Respiratory failure(CO2 retention ) Respiratory failure(CO2 retention )

Airway Anatomy Innervation Innervation Vagus n. Vagus n. Superior laryngeal n. Superior laryngeal n. External branch – motor to cricothyroid m. External branch – motor to cricothyroid m. Internal branch – sensory larynx above TVC’s Internal branch – sensory larynx above TVC’s Recurrent laryngeal n. Recurrent laryngeal n. Right – subclavian Right – subclavian Left – Aortic arch (board question) Left – Aortic arch (board question) Motor to all other muscles, Sensory to TVC’s and trachea Motor to all other muscles, Sensory to TVC’s and trachea

Airway

Management I-History: previous history of difficulty is the best predictor previous history of difficulty is the best predictor Inquire about:-Nature of difficulty -No of trials -No of trials -Ability to ventilate bet trials -Ability to ventilate bet trials -Maneuver used -Maneuver used -Complications -Complications II-Snoring and sleep apnea( prdictors of DMV)

LEMON -Look for any obvious anomaly  Morbid obesity(BMI)  Skull  Face  Jaw  Mouth,teeth  Neck

Examination I-The 3 joints movements  A-O joint(15-20 degrees) Presence of a gap bet the Occiput and C1 is essential  The cervical spine(range>90)  T.M joint:  Subluxation (1 finger)

Examine Airway The 3 – 3 – 2 rule Mouth open: 3 fingers Mouth open: 3 fingers Mentum to hyoid: 3 fingers Mentum to hyoid: 3 fingers Floor of mouth to thyroid cartilage: 2 fingers Floor of mouth to thyroid cartilage: 2 fingers

Mallampatti Mallampatti test: Based on the hypothesis That when the base of the Tongue is disproportionally Large it will overshadow the larynx

-Simple easy test,correlates with what is seen during laryngoscopy or Cormack-Lehene grades,but 1-moderate sensitivity and specificity(12% false +ve) 2-Inter observer variation 3-Phonation increases false negative view

II-Wilson test -Consists of 5 easily assessed factors  Body wight(n=0,>90=1,>110=2)  Head and neck movement  Jaw movement  Receding jaw  Buck teeth Each factor assigned as o,1,2 max is 10

Obstruction Apparent cause e.g. goitre Apparent cause e.g. goitre OSA OSA Noisy breathing or stridor Noisy breathing or stridor Signs of upper airway obstruction Signs of upper airway obstruction Other causes Other causes

Neck Mobility Prior condition Surgery Surgery Rheumatoid arthritis Rheumatoid arthritis Osteoarthritis Osteoarthritis Others Others

Proper Equipment -Bag and mask,oxygen source -Airways oro and nasopharyngeal -Laryngosopes different blades -ETT different sizes -suction on

Airway gadgets

Mask Ventilation Induction of anesthesia produces upper airway relaxation and possible collapse Induction of anesthesia produces upper airway relaxation and possible collapse Downward displacement of mask with thumb and index finger Downward displacement of mask with thumb and index finger

Requirement of successful intbation 1-Normal roomy mandible 1-Normal roomy mandible 2-Normal T-M, A-O, and C-spine 2-Normal T-M, A-O, and C-spine

Positioning for successful intubation 3-Alignment of 3 axes or Assuming sniffing position -Any anomaly in these 3 joints A-O, T-M or C-spine can result In difficult intubation

Endotracheal Intubation Look for epiglottis Look for epiglottis If initially not found insert laryngoscope further If initially not found insert laryngoscope further If this maneuver does not work slowly pull laryngoscope back If this maneuver does not work slowly pull laryngoscope back Once epiglottis visualized, push laryngoscope into vallecula and apply traction at 45 degree angle to “push” epiglottis up and out of the way Once epiglottis visualized, push laryngoscope into vallecula and apply traction at 45 degree angle to “push” epiglottis up and out of the way

Confirm tube position Direct visualization of ETT between cords Direct visualization of ETT between cords Bronchoscopy ;carina seen Bronchoscopy ;carina seen Continuous trace of capnography Continuous trace of capnography 3 point auscultation 3 point auscultation Esophageal detector device Esophageal detector device Other as bilateral chest movement,mist in the tube,CXR Other as bilateral chest movement,mist in the tube,CXR

Rapid sequence induction Indications Indications Technique: Technique: -Preoxygenation -Preoxygenation -IV induction with sux -IV induction with sux -Cricoid pressure -Cricoid pressure -Intubate, inflate the cuff,confirm position -Intubate, inflate the cuff,confirm position -Release cricoid and fix the tube -Release cricoid and fix the tube

Cricoid pressure Cricoid Pressure

Complications of intubation 1-Inadequate ventilation 2-Esophageal intubation 3-Airway obstruction 4-Bronchospasm5-Aspiration 6- Trauma 7-Stress response

Problems with ETT and Cuff ❏ Too long - endobronchial intubation ❏ Too short - accidental extubation ❏ Too large - trauma to surrounding tissues ❏ Too narrow - increased airway resistance ❏ Too soft - kinks ❏ Too hard - tissue damage ❏ Prolonged placement - vocal cord granulomas, tracheal stenosis ❏ Poor curvature - difficult to intubate ❏ Cuff insufficiently inflated - allows leaking and aspiration ❏ Cuff excessively inflated - pressure necrosis

Difficult airway Causes Causes-Congenital-Acquired

Airway gadgets

Rigid Fiberoptic Scope BullardWu Scope

Rigid Fiberoptic Scope Rigid Fiberoptic Scope UpsherGlideScope

Difficult airway Expected from history,examination Expected from history,examination Secure airway while awake under LA  Unexpected different options Priority for maintenance of patent airway and oxygenation

Transtracheal Jet Ventilation

Ventilation Spontaneous ventilation Spontaneous ventilation Controlled ventilation Controlled ventilation Pressure cycled and volume cycled ventilator -Tidal volume 10 mls/kg -Respiratory rate to maintain normocarbia -I:E ratio -PEEP

Recommendations Adequate airway assessment to pick up expected D.A to be secured awake Adequate airway assessment to pick up expected D.A to be secured awake Difficult intubation cart always ready Difficult intubation cart always ready Pre oxygenation as a routine Pre oxygenation as a routine Maintenance of oxygenation not the intubation should be your aim Maintenance of oxygenation not the intubation should be your aim Use the technique you are familiar with Use the technique you are familiar with Always have plan B,C,D in unexpected D.A Always have plan B,C,D in unexpected D.A

EXTUBATION General guidelines:  check that neuromuscular function and hemodynamic status is normal  check that patient is breathing spontaneously with adequate rate and tidal volume  allow patient to breathe 100% O2 for 3-5 minutes  suction secretions from pharynx  deflate cuff, remove ETT on inspiration (vocal cords abducted)  ensure patient breathing adequately after extubation  ensure face mask for O2 delivery available  proper positioning of patient during transfer to recovery room, e.g. sniffing position, side lying.

Oxygen Therapy Aim Aim to prevent or at least minimize tissue hypoxia. to prevent or at least minimize tissue hypoxia. Indications: Indications: When oxygen tension is less than 60 mmHg in a healthy patient. When oxygen tension is less than 60 mmHg in a healthy patient. N.B If patient has chronic lung disease may accept a lower oxygen tension before treatment. N.B If patient has chronic lung disease may accept a lower oxygen tension before treatment. Post operatively supplemental oxygen may be given if SaO2<92% especially if anemic, hypotensive, septic Post operatively supplemental oxygen may be given if SaO2<92% especially if anemic, hypotensive, septic Delivery of medication (e.g. nebulized salbutamol) Delivery of medication (e.g. nebulized salbutamol) Treatment of carbon monoxide poisoning Treatment of carbon monoxide poisoning

Hypoxemia Causes of tissue hypoxia: Low inspired oxygen tension Low inspired oxygen tension Hypoventilation Hypoventilation Poor matching of ventilated areas of lung with those areas being perfused Poor matching of ventilated areas of lung with those areas being perfused Impaired blood flow to tissues: Impaired blood flow to tissues: Low cardiac output - Hypotension -Arterial occlusion Low cardiac output - Hypotension -Arterial occlusion Impaired oxygen carrying capacity: Low hemoglobin concentration Impaired oxygen carrying capacity: Low hemoglobin concentration Abnormal hemoglobin (e.g. sickle cell) Abnormal hemoglobin (e.g. sickle cell) Poisoned hemoglobin (methemoglobin, carboxyhemoglobin) Poisoned hemoglobin (methemoglobin, carboxyhemoglobin) Impaired oxygen utilization by tissues: cyanide poisoning Impaired oxygen utilization by tissues: cyanide poisoning Excess oxygen utilization: Thyrotoxicosis - Malignant hyperthermia Excess oxygen utilization: Thyrotoxicosis - Malignant hyperthermia

Delivery systems: Nasal cannulae Nasal cannulae inspired oxygen concentration is dependent on the oxygen flow rate, the nasopharyngeal volume and the patient’s inspiratory flow rate. inspired oxygen concentration is dependent on the oxygen flow rate, the nasopharyngeal volume and the patient’s inspiratory flow rate. Increases inspired oxygen concentration by 3-4%. Increases inspired oxygen concentration by 3-4%. Oxygen flow rates greater than 3 liters are poorly tolerated by patients due to drying and crusting of the nasal mucosa. Oxygen flow rates greater than 3 liters are poorly tolerated by patients due to drying and crusting of the nasal mucosa.

Nasal cannulae

Face masks : Face masks : Three types of facemask are available; open, Venturi, non-rebreathing. Three types of facemask are available; open, Venturi, non-rebreathing. Open facemasks : Open facemasks : Are the most simple of the designs available. Are the most simple of the designs available. They do not provide good control over the oxygen concentration being delivered to the patient causing variability in oxygen treatment. They do not provide good control over the oxygen concentration being delivered to the patient causing variability in oxygen treatment. A 6l/min flow rate is the minimum necessary to prevent the possibility of rebreathing. A 6l/min flow rate is the minimum necessary to prevent the possibility of rebreathing. Maximum inspired oxygen concentration ~ 50-60%. Maximum inspired oxygen concentration ~ 50-60%.

Venturi facemasks They should be used in patients with COPD/emphysema where accurate oxygen therapy is needed. They should be used in patients with COPD/emphysema where accurate oxygen therapy is needed. Arterial blood gases can then be drawn so correlation between oxygen therapy for hypoxemia and potential risk of CO2 retention can be made. Arterial blood gases can then be drawn so correlation between oxygen therapy for hypoxemia and potential risk of CO2 retention can be made. Masks are available for delivering 24%, 28%, 35%, 40%, 50%. Masks are available for delivering 24%, 28%, 35%, 40%, 50%.

Non-rebreathing facemasks Non-rebreathing facemasks have an attached reservoir bag and one-way valves on the sides of the facemask. have an attached reservoir bag and one-way valves on the sides of the facemask. With flow rates of 10 liters an oxygen concentration of 95% can be achieved. With flow rates of 10 liters an oxygen concentration of 95% can be achieved. These masks provide the highest inspired oxygen concentration for non- intubated patients. These masks provide the highest inspired oxygen concentration for non- intubated patients.

Hazards of oxygen therapy These are usually related to prolonged treatment at high concentrations and include: These are usually related to prolonged treatment at high concentrations and include: Absorption atelectasis Absorption atelectasis Hypoventilation – Occurs in COPD patients Hypoventilation – Occurs in COPD patients Pulmonary toxicity Pulmonary toxicity Prolonged high concentrations of oxygen result in the production of free radicals -The resulting injury gives a clinical picture similar to ARDS ( adult respiratory distress syndrome). Prolonged high concentrations of oxygen result in the production of free radicals -The resulting injury gives a clinical picture similar to ARDS ( adult respiratory distress syndrome). The same toxicity results in bronchopulmonary dysplasia in newborn/premature The same toxicity results in bronchopulmonary dysplasia in newborn/premature babies. babies.

Dr. Adel Elshimy Date: 5/12/2011 T hank You T hank You

Reference book and the relevant page numbers.. American Society of Anesthesiologists ( accessed January 30, Anesthesia Patient Safety Foundation ( accessed January 30, Cooper JB, Gaba DM. A strategy for preventing anesthesia accidents. Int Anesthesiol Clin 1989;27:148–152. Cooper JB, Newbower RS, Kitz RJ. An analysis of major errors and equipment failures in anesthesia management: considerations for prevention and detection. Anesthesiology 1984;60:34–42. Gaba DM. Anaesthesiology as a model for patient safety in health care. BMJ 2000;320:785-“788. Available at: