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

Who Needs to be intubated? 1.供氧失敗 藉由脈搏血氧計(oximetry)(但容易因局部性或全身性灌流不足,嚴重貧血,與指甲油受到干擾),動脈血氧分析,或病人的發紺表現評估 2.通氣失敗 藉由鼻導管(cannula)上的二氧化碳分析儀(capnometry)(不一定總是反應真正的二氧化碳分壓,但可以提供通氣量改變的趨勢),動脈血氧分析,或病人呼吸作功的費力程度來評估. 3.無法保護呼吸道 有潛在異物嗆入的風險者,如痰量變得稠又多,咳嗽反射不足,抽痰後吞嚥功能不良等.嘔吐反射(gag reflex)無法正確評估呼吸道的保護效果. 4.神經學症狀或心肺功能惡化而需要轉送其他單位或緊急處置的病人

Prediction of Difficult Intubation 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 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 Respiratory arrest ARDS Acute respiratory distress with accessory muscle breathing Hypoxemia or hypercapnia with respiratory acidosis pH <7.3, PaO2 < 60mmHg or PaCO2 >45mmHg Severe chest contussion General anesthesia

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

Elements of ventilator settings Cycling How the ventilator switches from inspiration to expiration. Time cycled – such as in pressure controlled ventilation Flow cycled – such as in pressure support 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 Triggering What causes the ventilator to inspiration. Time – the ventilator cycles at a set frequency as determined by the controlled rate. Pressure – the ventilator senses the patient's inspiratory effort by way of a decrease in the baseline pressure. Flow – modern ventilators deliver a constant flow around the circuit throughout the respiratory cycle (flow-by). 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 Breath pattern What causes the ventilator to cycle from inspiration. Mandatory (controlled) - which is determined by the respiratory rate. Assisted - as in assist control, synchronized intermittent mandatory ventilation, pressure support Spontaneous - no additional assistance in inspiration, as in CPAP

Elements of ventilator settings Flow pattern 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 Mode 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 Oxygen in Carbon dioxide out  FIO2  mean alveolar pressure PEEP Re-open alveoli and  shunt Carbon dioxide out  ventilation  RR  tidal volume In summary, the most important means of improving oxygenation are increasing the inspired concentration of oxygen, increasing the mean airway and therefore the mean alveolar pressure and applying PEEP to re-open alveoli. Carbon dioxide removal can be increased by increasing the respiratory rate or tidal volume

非侵入性正壓呼吸器 Mark 7 (IPPB)

Evidences for Use of NPPV

Contraindications to NIV

Thank you very much for attention!