Airway and Mechanical Ventilator Skills and Knowledge Contents

Airway and Mechanical Ventilator Skills and Knowledge 部立雙和醫院胸腔內科 內科加護病房 陳資濤

Contents l l l Evaluate the patients who needs intubation Introduction of mechanical ventilation Ventilator settings l l Elements of ventilator settings Introduction of non-invasive ventilation (NIV)

Prediction of Difficult Intubation l l l L = Look (觀察) E = Evaluate the mouth opening and airway position (評估開口程度與氣道位置) M = Mallampati score O = Obstruction (排除阻塞) N = Neck mobility (評估頸部活動度)

The 3 -3 -2 Rule l l l 3: The mouth opening ≧ 3 fingers 3: Tip of the chin to the hyoid bone ≧ 3 fingers 2: Hyoid bone to the top of the thyroid cartilage ≧ 2 fingers

Mallampati Score

傳統/高階呼吸器 Bennett MA-1 Dräger Evita XL

Indications for Mechanical Ventilation l l Respiratory arrest ARDS Acute respiratory distress with accessory muscle breathing Hypoxemia or hypercapnia with respiratory acidosis l l l p. H <7. 3, Pa. O 2 < 60 mm. Hg or Pa. CO 2 >45 mm. Hg Severe chest contussion General anesthesia

Elements of ventilator settings l Control How the ventilator knows how much flow to deliver. l Volume Controlled (volume limited, volume targeted) and Pressure Variable l Pressure Controlled (pressure limited, pressure targeted) and Volume Variable l Dual Controlled (volume targeted (guaranteed) pressure limited)

Elements of ventilator settings l Cycling How the ventilator switches from inspiration to expiration. l Time cycled – such as in pressure controlled ventilation l Flow cycled – such as in pressure support l Volume cycled – the ventilator cycles to expiration once a set tidal volume has been delivered: this occurs in volume controlled ventilation. If an inspiratory pause is added, then the breath is both volume and time cycled

Elements of ventilator settings l Triggering What causes the ventilator to inspiration. l Time – the ventilator cycles at a set frequency as determined by the controlled rate. l Pressure – the ventilator senses the patient's inspiratory effort by way of a decrease in the baseline pressure. l Flow – modern ventilators deliver a constant flow around the circuit throughout the respiratory cycle (flowby). A deflection in this flow by patient inspiration, is monitored by the ventilator and it delivers a breath. This mechanism requires less work by the patient than pressure triggering.

Elements of ventilator settings l Breath pattern What causes the ventilator to cycle from inspiration. l Mandatory (controlled) - which is determined by the respiratory rate. l Assisted - as in assist control, synchronized intermittent mandatory ventilation, pressure support l Spontaneous - no additional assistance in inspiration, as in CPAP

Elements of ventilator settings l Flow pattern l l Sinusoidal - this is the flow pattern seen in spontaneous breathing and CPAP Decelerating - most intensivists and respiratory therapists use this pattern in volume targeted ventilation also, as it results in a lower peak airway pressure than constant and accelerating flow, and better distribution characteristics Constant - flow continues at a constant rate until the set tidal volume is delivered Accelerating - flow increases progressively as the breath is delivered. This should not be used in clinical practice.

Elements of ventilator settings l Mode l l CMV - Conventional controlled ventilation, without allowances for spontaneous breathing. Many anesthesia ventilators operate in this way. Assist-Control - Where assisted breaths are facsimiles of controlled breaths. Intermittent Mandatory Ventilation - Which mixes controlled breaths and spontaneous breaths. Breaths may also be synchronized to prevent "stacking". Pressure Support - Where the patient has control over all aspects of his/her breath except the pressure limit.

CMV

A/CV

SIMV

PSV (pressure support ventilation) Spontaneous inspiratory efforts trigger the ventilator to provide a variable flow of gas in order to attain a preset airway pressure. Can be used in adjunct with SIMV.

Main determinants l Oxygen in l l l F IO 2 mean alveolar pressure PEEP l Re-open alveoli and shunt l Carbon dioxide out l ventilation l RR l tidal volume

Evidences for Use of NPPV

Contraindications to NIV

Thank you very much for attention!