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9EVeC Course Notes These notes are prepared for educational purposes for participants of the 9EVeC Ventilator Course.They are not a substitute for clinical judgement, institutional guidelines, or specialist consultation.While every effort has been made to ensure accuracy, the course faculty and organizers assume no responsibility for any injury, loss, or damage incurred as a result of reliance upon the information provided in these notes.These notes are for internal use by 9EVeC attendees only. Reproduction, modification, commercial distribution, or public posting (including social media) is not permitted without written permission from the course director.
CONTENTS Lecture 1 — Basic Lung Mechanics- page 1 Lecture 2 — Ventilator Modes & Initiation Principles – page 8 Lecture 3 — Waveforms & Scalars – page 12 Lecture 4 — Strategies for Restrictive Lung Disease page 25 Lecture 5 — Strategies for Obstructive Lung Disease – page 27 Lecture 6 — Alarm Management & Troubleshooting – page 29 Lecture 7 — High Flow Nasal Cannula (HFNC) – page 31 Lecture 8 — Non-Invasive Ventilation (NIV) – page 34 Addendum — Ventilation Strategy for Special Conditions – page 37
ABBREVIATIONSABG – Arterial Blood GasAC – Assist ControlBiPAP – Bilevel Positive Airway PressureCPAP – Continuous Positive Airway PressureCstat – Static ComplianceDOPES – Dislodged tube, Obstruction, Pneumothorax, Equipment failure, Stacked breathsDP – Driving Pressure (Pplat – PEEP)EPAP – Expiratory Positive Airway PressureFiO₂ – Fraction of Inspired OxygenHFNC – High Flow Nasal CannulaHACOR Score – Heart Rate, Acidosis, Consciousness, Oxygenation, Respiratory RateI:E – Inspiratory to Expiratory RatioICP – Intracranial PressureIPAP – Inspiratory Positive Airway PressureMAP – Mean Arterial PressureNIV – Non-Invasive VentilationPEEP – Positive End-Expiratory PressurePID – Patient Inspiratory DemandPIP – Peak Inspiratory PressurePplat – Plateau PressurePS – Pressure SupportRaw – Airway ResistanceROX Index – (SpO₂ / FiO₂) / Respiratory RateRR – Respiratory RateSIMV – Synchronized Intermittent Mandatory VentilationTBI – Traumatic Brain InjuryTE – Expiratory TimeTi – Inspiratory TimeVCV – Volume Control VentilationVt – Tidal Volume
9EVeC 2025 I Negeri Sembilan Emergency Ventilator Course1LECTURE 1UNDERSTANDING BASIC LUNG MECHANICS● Waveform displays show what is actually happening inside the patient’s lungs during ventilation.● The ventilator settings (such as tidal volume, respiratory rate, FiO₂, and PEEP) represent what we intend to happen during ventilation.● Using inspiratory and expiratory hold functions allows accurate assessment of airway pressures instead of guessing from waveforms.Pressure–Volume Relationship● Pressure, volume, and compliance are related by the formula P = V ÷ C.● When tidal volume is increased, airway pressure will increase accordingly.● When tidal volume is decreased, airway pressure will decrease.● This means that changing tidal volume directly changes how much pressure is delivered to the lungs.COMPLIANCE● Compliance describes how easily the lungs expand when air enters, and it is calculated using C = ΔV/ΔP● Normal lung compliance ranges between 50–100 mL/cmH₂O.● Low compliance (also known as a stiff lung) requires high pressure to deliver even a small volume of air.● Diseases such as ARDS, pulmonary fibrosis, pulmonary edema, and pneumothorax commonly result in low compliance.● High compliance (also known as a floppy lung) allows large volume changes with very little pressure, as seen in conditions such as emphysema.
9EVeC 2025 I Negeri Sembilan Emergency Ventilator Course2Elastance● Elastance is the opposite of compliance and describes the tendency of the lungs to recoil inward after being inflated.● Elastance is calculated using E = 1/C, which means that as compliance decreases, elastance increases.● Stiff lungs have high elastance, while floppy lungs have low elastance.Airway Resistance (Raw)● Airway resistance refers to the opposition to airflow caused by friction between gas molecules and the airway wall.● According to Poiseuille’s Law, resistance increases dramatically when airway radius becomes smaller.● Halving the radius of an airway causes a 16-fold increase in resistance.● Clinical causes of increased resistance include bronchospasm, mucus plugging, airway edema, secretions, and small endotracheal tube size.● Longer tubes and thick, viscous airway secretions also increase resistance.
9EVeC 2025 I Negeri Sembilan Emergency Ventilator Course3Total Airway Pressure● Total airway pressure is made up of resistive pressure (to push air through the airways) and elastic pressure (to expand the lungs and chest wall).● Resistive pressure depends on airway resistance, while elastic pressure depends on compliance.●Peak Inspiratory Pressure (PIP)● Peak inspiratory pressure is the maximum airway pressure achieved at the end of inspiration.● PIP reflects both airway resistance and lung compliance.● PIP increases when airway resistance increases or when lung compliance decreases.● High PIP is not always dangerous, but it requires further assessment with a plateau pressure measurement.●
9EVeC 2025 I Negeri Sembilan Emergency Ventilator Course4Plateau Pressure (Pplat)● Pplat is measured during an inspiratory hold when airflow is zero.● Pplat reflects true alveolar pressure and represents the elastic component of airway pressure only.● Pplat pressure increases when lung compliance decreases.● To minimize ventilator-induced lung injury, the target plateau pressure is less than 30 cmH₂O.
9EVeC 2025 I Negeri Sembilan Emergency Ventilator Course5Differentiating Pip And Pplat● If both PIP and Pplat are increased, the problem is likely reduced lung compliance, such as in ARDS or pulmonary edema.● If PIP is increased but Pplat remains normal, the problem is likely increased airway resistance, such as bronchospasm or mucus plugging.● Performing an inspiratory hold is essential to distinguish between resistance and compliance problems.
9EVeC 2025 I Negeri Sembilan Emergency Ventilator Course6Positive End-Expiratory Pressure (PEEP)● PEEP refers to the positive pressure that remains in the lungs at the end of expiration.● Normal physiological PEEP is between 3–5 cmH₂O, and typical mechanical ventilation uses PEEP between 5–10 cmH₂O.● PEEP prevents alveoli from collapsing, increases functional residual capacity, improves ventilation–perfusion matching, and reduces work of breathing.
9EVeC 2025 I Negeri Sembilan Emergency Ventilator Course7Tidal Volume (Vt)● Tidal volume is the volume of air delivered per breath.● The recommended tidal volume for protective ventilation is 6–8 mL/kg of ideal body weight.● Excessive tidal volume increases the risk of volutrauma, while very low tidal volume may result in hypercapnia.Dead Space (Vd)● Dead space refers to the portion of inspired air that does not participate in gas exchange.● Total dead space includes anatomic dead space, alveolar dead space, and mechanical dead space from ventilator circuits and artificial airways.Ventilation Variables● Alveolar ventilation (VA) is calculated using VA = (Vt – Vd) × RR.● Minute ventilation (MV) is calculated using MV = Vt × RR, and normal values range from 6–10 L/min.● Increased dead space reduces alveolar ventilation and impairs CO₂ clearance.
9EVeC 2025 I Negeri Sembilan Emergency Ventilator Course8LECTURE 2 BASIC MECHANICAL VENTILATION MODES & INITIATIONThe Respiratory Cycle● Trigger (Start): What causes the breath to begin?o Time-triggered: Machine initiates based on a set rate.o Pressure/Flow-triggered: Patient initiates by creating negative pressure or flow change.● Limit/Target (Sustain): What variable is controlled during inspiration?o The ventilator maintains either a set Flow (Volume Control) or a set Pressure (Pressure Control)● Cycle (End): What causes the breath to end (inspiration to expiration)?o Can be cycled by Volume, Pressure, or Time.
9EVeC 2025 I Negeri Sembilan Emergency Ventilator Course9Control Variables: Volume vs PressureEvery mode is defined by what is set (independent) and what changes (dependent).Feature Volume Control (VC) Pressure Control (PC)Preset Variable Tidal Volume Inspiratory Pressure (Pinsp) Variable Peak Pressure (Ppeak) varies based on lung complianceTidal Volume (Vt) varies based on lung compliancePros Guarantees Minute Ventilation (Mv = Vt x RR)Limits peak pressures (lung protection)Cons High pressures if lung compliance is low (Risk of barotrauma)Unstable Vt if resistance is high or compliance is low
9EVeC 2025 I Negeri Sembilan Emergency Ventilator Course10Breath TypesUnderstanding who does the work is crucial.● Mandatory (Controlled): Ventilator does ALL the work. Triggered by time or patient, but the machine controls the breath.● Assisted: Patient triggers the breath, but the ventilator takes over and delivers a full preset breath.● Spontaneous (Supported): Patient triggers and cycles the breath. The ventilator only provides some support (Pressure Support).Common Ventilator ModesA. Assist Control (AC)● Concept: A mix of mandatory and assisted breaths. Every breath (whether triggered by machine or patient) delivers the same full preset Tidal Volume or Pressure.● Indication: Critically ill patients needing full support.● Risk: Hyperventilation can lead to Respiratory Alkalosis or Auto-PEEP (air trapping).B. SIMV (Synchronized Intermittent Mandatory Ventilation)● Concept: A mix of mandatory and spontaneous breaths.○ Mandatory breaths: Delivered at the set rate (full support).○ Spontaneous breaths: Patient breathes between mandatory breaths. These are not fully supported (patient determines their own volume). The partial support was determined by the Preset Pressure Support (PS)● Indication: Weaning patients or those with good spontaneous effort.● Pros: Better patient comfort; lowers mean airway pressure compared to AC.
9EVeC 2025 I Negeri Sembilan Emergency Ventilator Course11Initiation of Settings (Mnemonic: MOVE - PAIR)● M - Mode: Choose AC or SIMV (VC or PC)● O - Oxygen (FiO2): Start at 100%, then titrate down (<60%) to keep SpO2 90-96% (88-92% for COPD/ARDS).● V - Volume (VT):o Normal Lungs: 8 ml/kgo Asthma/COPD: 6-8 ml/kgo ARDS: 4-6 ml/kg (Lung protective).● E - End Expiratory Pressure (PEEP): Start at 3-5 cmH2O. Higher for ARDS.● P - Pressure Support (PS): Set at 10 cmH2O (or 2x PEEP) to overcome tube resistance.● A - Adequate Sedation: Essential for tolerance.● I - I:E Ratio: Start at 1:2. Use 1:3 or 1:4 for Asthma/COPD to allow more time to exhale.● R - Rate (RR):o Start at 12-20 bpm.o Asthma/COPD: Lower (8-10 bpm) to prevent air trapping.o Metabolic Acidosis/ARDS: Higher rates may be needed
9EVeC 2025 I Negeri Sembilan Emergency Ventilator Course12LECTURE 3 WAVEFORM & SCALAR - IZNI• Respiratory function monitoring integrates multiple data points such as airway pressure, flow, and volume to evaluate pulmonary mechanics.• Ventilator graphics are essential tools in the management of mechanically ventilated patients.• Failure to recognize abnormalities in waveforms may result in complications or inappropriate ventilator settings.Types of Ventilator Scalars• The three primary ventilator scalars are:o Pressure–time scalaro Flow–time scalaro Volume–time scalar
9EVeC 2025 I Negeri Sembilan Emergency Ventilator Course13Pressure–Time Scalar (PTS)• The pressure–time scalar provides PIP (peak inspiratory pressure) and plateau pressure (P-plat), which help assess lung mechanics.• It is useful in identifying air trapping, evaluating trigger efforts, and determining ventilation mode.• PIP is the maximum pressure achieved during inspiration and reflects the pressure needed to deliver the set tidal volume.• P-plat represents alveolar pressure at end-inspiration when airflow is zero.o Select Inspiratory Hold / Inspiratory Pause to measure P-plat directly from the pressure–time scalar.o Plateau pressure should be kept below 30 cmH₂O to prevent barotrauma.• Transairway pressure (PTA) is calculated as:→ PIP – P-plat and indicates pressure needed to overcome airway resistance.High PIP with high P-plat High PIP with normal P-platSuggests a compliance problem, often due to:• Pneumonia• Pulmonary edema• ARDS• Pneumothorax• Chest wall stiffnessSuggests an airway resistance problem, such as:• Bronchospasm• Mucous plugging• Retained secretions• ETT tip occlusion
9EVeC 2025 I Negeri Sembilan Emergency Ventilator Course14Detecting Air Trapping• Intrinsic PEEP (auto-PEEP) can be identified using Expiratory Hold.• Intrinsic PEEP is calculated as:→ Total PEEP – Set PEEP•Triggering• Trigger types include machine trigger and patient trigger.• Recognition of trigger sensitivity helps prevent breath-stacking or missed triggers.
9EVeC 2025 I Negeri Sembilan Emergency Ventilator Course15Ventilation Modes• Volume control and pressure control can be differentiated based on the pressure waveform pattern:o Volume control → Sharp pressure rise with characteristic peak.o Pressure control → Square or decelerating pressure pattern.
9EVeC 2025 I Negeri Sembilan Emergency Ventilator Course16Flow–Time Scalar (FTS)The flow–time scalar helps identify:• Air trapping• Bronchodilator response• Ventilation mode• Airway obstructionFlow Pattern• In a single breath cycle, the inspiratory flow is positive and expiratory flow is negative.Air Trapping• Air trapping (auto-PEEP) appears as failure of expiratory flow to return to the baseline before the next breath begins.• This suggests insufficient time for full exhalation.
9EVeC 2025 I Negeri Sembilan Emergency Ventilator Course17‘Bronchodilator Response• A bronchodilator response can be seen when expiratory flow increases and the curve becomes sharper after bronchodilator therapy.Mode Recognition• Pressure control ventilation produces constant inspiratory flow with decelerating expiration.• Volume control ventilation typically shows a square-wave inspiratory flow pattern.
9EVeC 2025 I Negeri Sembilan Emergency Ventilator Course18Volume–Time Scalar (VTS)The volume–time scalar helps evaluate:• Tidal volume• Air trapping• Volume leaksVolume Leak• A leak is suspected when the inspiratory and expiratory volumes do not return to equilibrium.• A consistent volume deficit indicates a leak, often from:o ETT cuffo Circuit disconnectiono Face mask fit (in NIV)
9EVeC 2025 I Negeri Sembilan Emergency Ventilator Course19Ventilator Loops• Loops are two-dimensional representations of two variables plotted against each other.• The main types are:o Pressure–volume loopo Flow–volume loop• Each loop presents both an inspiratory and expiratory limb, allowing assessment of respiratory mechanics and pathology.Pressure–Volume Loop (PV Loop)• The loop begins at functional residual capacity (FRC) and returns to FRC after expiration.• The inspiratory limb ends when preset volume or pressure is achieved.• Inflection Pointso Lower Inflection Point (LIP) indicates the pressure at which alveoli begin to open.o Upper Inflection Point (UIP) indicates where overdistension begins.
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9EVeC 2025 I Negeri Sembilan Emergency Ventilator Course21Compliance Changes• A steeper loop indicates high compliance (e.g., emphysema).• A flattened loop indicates low compliance (e.g., ARDS, pulmonary edema).
9EVeC 2025 I Negeri Sembilan Emergency Ventilator Course22Overdistension (“Beak Sign”)• The beak effect shows rising pressure without corresponding volume change, which indicates harmful alveolar overdistension.•Air Leak Detection• A shift in the inspiratory and expiratory limbs that do not meet suggests volume leak within the system.•
9EVeC 2025 I Negeri Sembilan Emergency Ventilator Course23Flow–Volume Loop (FV Loop)• Peak Inspiratory Flow Rate (PIFR) and Peak Expiratory Flow Rate (PEFR) describe flow capacity.• A scooped-out expiratory limb indicates airway obstruction (e.g., bronchospasm).Obstructive Pattern• Obstructive airway disease shows:o Lower PEFRo Concave (\"scooped\") expiratory limbo Reduced expiratory flow returning to baselineo
9EVeC 2025 I Negeri Sembilan Emergency Ventilator Course24Aiir Trapping• Air trapping is suspected when expiration does not return to zero baseline before the next breath.Aiir Leak• When the expiratory volume does not return to zero, the deficit of volume indicates magnitude of air leak•
9EVeC 2025 I Negeri Sembilan Emergency Ventilator Course25LECTURE 4STRATEGIES FOR RESTRICTIVE LUNG DISEASEKey Pressures & What They MeanPeak Pressure (Ppeak)Total pressure needed to push air inAffected by resistance (bronchospasm, secretions, ETT issues)Plateau Pressure (Pplat)Alveolar pressure (no flow)Indicates lung + chest wall stiffnessTarget < 30 cmH₂ODriving Pressure (DP)DP = Pplat – PEEPBest indicator of lung stressTarget < 15 cmH₂OCompliance (Cstat)Cstat = VT / (Pplat – PEEP)Normal: 50–60 mL/cmH₂OLow = restrictive physiologyProtective Ventilation Strategy (Use for ARDS & Restrictive Lungs)● VT: 6–8 mL/kg PBW● Pplat: < 30● DP: < 15● PEEP: Enough to maintain alveolar recruitment● Oxygenation target:o SpO₂ 88–92%o PaO₂ 55–80 mmHg● Allow permissive hypercapnia: pH ≥ 7.20Why?→ Reduces volutrauma, atelectrauma, barotrauma, and inflammation.PEEP Optimization (Maximal Compliance Method)Goal: Find the PEEP that gives the best compliance and lowest stress.Steps:1. Start at PEEP 5–8 cmH₂O2. Increase by +2 cmH₂O3. Reassess Cstat at each step
9EVeC 2025 I Negeri Sembilan Emergency Ventilator Course264. Stop when Cstat no longer improves5. Choose the PEEP before the drop6. Ensure DP < 15 and Pplat < 30This method prevents:o Too little PEEP → collapse (atelectrauma)o Too much PEEP → overdistension (volutrauma)Troubleshooting High PressuresHigh Ppeak + High Pplat High Ppeak + Normal PplatCompliance problem● ARDS● Pneumonia● APO● Pleural effusion● Obesity / chest wall stiffnessResistance problem● Bronchospasm● Secretions● ETT obstruction / kinkingWho Should Receive Protective Ventilation?● ARDS● Severe pneumonia● Lung restrictive diseases● Patients “at risk” of ARDS (sepsis, trauma, aspiration)● Obesity, high IAP, pleural disease● Post–cardiac arrest● Non-obstructive airway diseases
9EVeC 2025 I Negeri Sembilan Emergency Ventilator Course27LECTURE 5STRATEGIES FOR OBSTRUCTIVE LUNG DISEASEThe core challenge in ventilating obstructive lung diseases (like severe asthma or COPD exacerbations) is managing severe airflow limitation, gas trapping, dynamic hyperinflation, and intrinsic PEEP (auto-PEEP)Pathophysiology & Detection• Auto-PEEP is gas trapping because the patient cannot fully exhale before the next inhalation, creating additional positive pressure in the chest.• It causes increased Work of Breathing (WOB), reduces preload, and can lead to decompensation and hemodynamic compromise.Detection of Auto-PEEP:• Expiratory flow curve never returns to zero.• End-expiratory breath hold maneuver.• Difficulty triggering the ventilator.• Target for Ventilation: Keep intrinsic PEEP (IPEEP) < 10 and Plateau Pressure (P~Plat) < 25.Ventilation Strategy (7 Key Principles)1. Mode of Ventilation:o Both Volume Control (VC) and Pressure Control (PC) have pros and cons.o VC: Guarantees tidal volume (Vt) but risks barotrauma due to high pressures.o PC: Protects airways by setting a maximum inspiratory pressure (Ppeak), but Vt can vary.2. Increase Expiratory Time (T_E)o The main goal is to allow more time for exhalation and reduce air trapping. o This is done via four maneuvers: Decrease Respiratory Rate (RR) to 10-12. Decrease Inspiratory-to-Expiratory (I:E) ratio to 1:4 or 1:5. Reduce Inspiratory Time (Ti) Increase Inspiratory Flow (Insp flow).3. Low Tidal Volume (Vt):o Start with 6-8~ml/kg and titrate down to 4~ml/kg if needed, watching the flowtime scalar for air trapping.4. Plateau Pressure Monitoring:o Use the inspiratory hold maneuver to measure P~Plat, which estimates endinspiratory alveolar pressure. o Keep P~Plat < 30~cm~H_2O to minimize complications.
9EVeC 2025 I Negeri Sembilan Emergency Ventilator Course28o A high Peak Inspiratory Pressure (PIP) with a normal P~Plat usually indicates airway resistance issues (e.g., bronchospasm, mucous plug).5. Permissive Hypercapnia: o Intentionally allow the pH to fall rather than aggressively ventilating to control CO2. o Hypercapnia is generally well tolerated, and over-aggressive ventilation to correct it is often more harmful.6. PEEP Use (External PEEP): o Can benefit the patient by stenting open airways during expiration, reducing airway resistance, and decreasing WOB.o Default: Set PEEP at 5~cmo If passive on ventilator: Titrate PEEP to \\sim75\\% of the measured intrinsic PEEP.7. FiO2 Titration:o Aim for SpO2 > 91% and PaO2 > 60~mmHg. o Hyperoxia can be harmful by degrading V/Q matching.
9EVeC 2025 I Negeri Sembilan Emergency Ventilator Course29LECTURE 6ALARM & TROUBLESHOOTINGVentilator alarms are crucial for identifying abnormal conditions such as faulty equipment, leaks, patient disconnection, and changes in lung compliance or airway resistance.Alarm Classification and Priority• Alarms are categorized into o Input (power/gas supply), o Control (settings/self-test), and o Output (Pressure/Volume/Flow/Time). • They are prioritized by urgency:Level Priority Type of Event Examples1 Highest Immediately lifethreateningElectrical or pneumatic power failure, exhalation valve failure2 High Eventually lifethreateningHigh airway pressure, low exhaled minute volume, inverse I:E ratio. 3 Low Not life-threatening Short period of high respiratory rate, one-time high airway pressure.High Pressure Alarm Differentiation• A High Pressure Alarm indicates a problem, which is differentiated by checking the Plateau Pressure (pPlat) using the inspiratory hold maneuver.• pPlat reflects compliance (pressure to inflate the alveoli/lung).• The difference between Peak Inspiratory Pressure (PIP) and pPlat reflects resistance (pressure to get air to the alveoli).NormalpPlatHigh resistance (airway/tube)• Kinked/obstructed ETT• Mucus plug/secretions,• Bronchospasm• Water in circuit.ElevatedpPlatLow Compliance (Alveoli/Lung)• ARDS, pneumonia• pulmonary edema• pneumothorax• massive ascites• morbid obesity
9EVeC 2025 I Negeri Sembilan Emergency Ventilator Course30Other Key AlarmsAlarm Type Common Causes Setting RationaleLow Pressure / Low VolumeCircuit disconnection, ETT cuff deflated, ETT dislodged, leak in exhalation valveLow pressure alarm: set ~2 cmH₂O below PEEP for leak/disconnect detectionHigh Frequency (RR)Pain, agitation, fatigue, auto-triggering (incorrect sensitivity)Set at 30–35 breaths/min to prevent tachypnea and hyperventilationApnea Leaks, disconnections, or inadequate ventilator supportApnea time: 20 seconds (standard adult setting)High PEEP Auto-PEEP (air trapping) is the most common causeN/ASystematic Approach to Alarms• Follow a stepwise approach, starting with the patient:• Assess the Patiento Immediately check for distress. o If crashing, disconnect from the ventilator and begin manual bag ventilation (BVM) with FiO2 100%• Identify the Alarm:o Note the specific alarm type and severity on the ventilator screen.o Troubleshoot (Systemic ABCs):A: Airway: - Check ETT placement, cuff inflation, and for obstruction (biting, mucus plug). - Intervention includes repositioning ETT and suctioning.B: Breathing - Observe chest rise/fall- Auscultate breath sounds- Check SPO2- Assess for acute issues (pneumothorax, bronchospasm).C: Circuit - Inspect for disconnections, kinks, and condensation/water buildup. • If all else fails, consider Equipment Malfunction and switch to a BVM/backup ventilator.Mnemonic for Life-Threatening Conditions: DOPES• Dislodged/displaced ETT• Obstructed ETT• Pneumothorax• Equipment failure• Stacked breathing (auto-PEEP)
9EVeC 2025 I Negeri Sembilan Emergency Ventilator Course31LECTURE 7HIGH FLOW NASAL CANNULA (HFNC) THERAPYWhat is HFNC?Non-invasive respiratory support designed to deliver:● Flow: Up to 60 L/min**● FiO₂: 0.21–1.0● Temperature: Heated to 31–37°C, 100% humidityEvidence & Mechanisms● Dead space washout → rapid clearance of CO₂-rich gas from nasal cavity & pharynx● Less rebreathing, better alveolar ventilation ● PEEP-like effect 1 cm H₂O for every 10 L/min (mouth closed) ● Reduced O₂ dilution: High flows exceed patient’s inspiratoty demands (PID) thus reduce entrainment of room air ● Improved mucociliary clearance with heated, humidified gas reduces airway inflammationIndications● Mild–moderate of acute hypoxemic respiratory failure● Hypercapnic respiratory failure** when NIV not tolerated● Pre-oxygenation for RSI**● Increased **work of breathing**● Acute heart failure** with mild–moderate hypoxemia● Oxygen therapy post-extubation / weaning from IMVContraindicationsAbsolute contraindication Relative contraindicationAny situation that requires immediate intubation (e.g., impending airway obstruction, severe respiratory failure with altered consciousness).Conditions that prevent an adequate nasal seal:Facial or nasal structural abnormalitiesPrevious facial, nasal, or airway surgeryTumours or significant deformities of the upper airway
9EVeC 2025 I Negeri Sembilan Emergency Ventilator Course32Initiation SettingsTemperature o Set between 31–37 °C, adjusted based on patient comfort.Flow o Start at 30 L/mino Increase in 10 L/min increments up to a maximum of 60 L/mino Increase flow if there is:- Increased work of breathing (WOB)- Increased respiratory rate (RR)- Desaturation despite FiO₂ adjustmentsFiO₂ o Start at 0.6 (60%)o Titrate to maintain target oxygen saturations:- 92–96% (general population)- 88–92% (COPD or patients with chronic hypercapnia)Monitoring● Continuous reassessment of:o RR, WOB, SpO₂, heart rate, blood pressure, and ABG when indicatedo Patient comfort, humidification level, and presence of mouth breathingROX Index● Formula: ROX = (SpO₂ / FiO₂) / RR● A ROX Index > 4.88 at 2, 6, and 12 hours is associated with a low risk of HFNC failure.Weaning Strategy● Ensure clinical improvement (↓ RR, ↓ WOB, stable SpO₂).● Reduce FiO₂ first to ≤ 40%.● Then reduce flow by 5–10 L/min every 2–4 hours.● Consider stopping HFNC when:o Flow is < 20 L/min, ando FiO₂ is < 30%.● Post-HFNC options: nasal cannula, Venturi mask, or simple face mask.
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9EVeC 2025 I Negeri Sembilan Emergency Ventilator Course34LECTURE 8NON-INVASIVE VENTILATIONIntroduction & History● Definition: NIV provides ventilatory support without an invasive artificial airway (like an endotracheal tube).● Goal: To increase Functional Residual Capacity (FRC) and reduce the Work of Breathing (WOB).● Evolution: Started with negative pressure ventilation (Iron Lung) during Polio epidemics in the 1940s-50s before evolving to positive pressure techniques.Key Principles of NIVNIV works through three main physiological mechanisms:1. Restoring Functional Residual Capacity (FRC): Prevents alveolar collapse (atelectasis) by maintaining pressure in the lungs. 2. Lung Recruitment: Opens up collapsed lung areas to improve gas exchange.3. Reducing Work Threshold: Offsets \"Intrinsic PEEP\" (trapped air) to lower the effort required for the patient to trigger a breath.The Do’s & Don’ts:DO DON'TSelect patients wisely Use excessive sedation Choose appropriate settings & interface Forget contraindications Closely estimate patient response (monitor success/failure) Use NIV in moderate-to-severe ARDS (high failure risk) Patient Selection (When to Use?)Hypoxemic Respiratory Failure (\"Cannot Oxygenate\")Hypercapnic Respiratory Failure (\"Cannot Ventilate\")Best Evidence: Pulmonary Edema (Shown to reduce mortality & intubation rates)1.Use Caution (Less Evidence): ARDS and PneumoniaBest Evidence: COPD (Shown to reduce mortality & intubation rates)Use Caution (Less Evidence): Asthma
9EVeC 2025 I Negeri Sembilan Emergency Ventilator Course35Contraindications (The Don'ts)Do not use NIV if the patient exhibits:● Instability: Hemodynamic instability, unstable cardiac arrhythmia, or respiratory/cardiac arrest.● Airway Issues: Inability to protect their own airway, high aspiration risk, or copious/unmanageable secretions.● Physical Barriers: Facial burns, trauma, or deformity● Severe Status: Severe hypoxemia, severe acidosis, or massive agitationChoosing the Type: CPAP vs. BIPAPCPAP (Continuous Positive Airway Pressure)BIPAP (Bilevel Positive Airway Pressure):Mechanism Stents open alveoli to decrease shunt physiology; reduces cardiac preload and myocardial demand.Uses two separate pressures: IPAP (Inspiratory) and EPAP (Expiratory).Adjustment Increase EPAP to improve hypoxia (Note: EPAP is similar to PEEP).Increase Pressure Support (the difference between IPAP and EPAP) to improve ventilation.Adjusting NIV Settings• Standard Starting Point: IPAP 10 / EPAP 5 (Pressure Support of 5).• Troubleshooting Rules:o To improve Oxygenation: Increase EPAP.o To improve Ventilation (VT): Increase IPAP.o Critical Caution: You must maintain the difference between IPAP and EPAP. If you raise EPAP (e.g., to 8) without raising IPAP, you shrink the driving pressure, which will reduce the patient's tidal volume.Interface SelectionChoosing the right mask is critical for success.• Types: Nasal mask, Oronasal (Face) mask, Full face mask, Helmet.• Ideal Interface Features:o Well tolerated with no leaks.o Minimal dead space to prevent CO2 rebreathing.o Allows speaking and swallowing if possible.o Adapted to the patient’s specific anatomy.
9EVeC 2025 I Negeri Sembilan Emergency Ventilator Course36Monitoring Clinical ParametersOnce NIV is started, you must estimate the patient's response by monitoring:• Patient Comfort: Tolerance of the interface and sedation/delirium levels.• Breathing Effort: Respiratory rate, dyspnea, and use of accessory muscles.• Safety: Consciousness (GCS), ability to protect airway/cough, and gastric distention.• Scoring: Disease severity scores (like APACHE II).Predicting Success vs. Failure (HACOR Score)The slides highlight the HACOR Score as a tool to predict NIV failure in hypoxemic patients.• Parameters: Heart rate, Acidosis, Consciousness, Oxygenation, Respiratory rate.• Key Finding: A HACOR score > 5 at 1 hour of NIV predicts high failure rates. Early intubation (≤ 12 hours) is associated with lower mortality compared to late intubation (> 12 hours).
9EVeC 2025 I Negeri Sembilan Emergency Ventilator Course37ADDENDUMVENTILATION STRATEGY FOR SPECIAL CONDITIONSTraumatic Brain Injury (TBIObjectives of Ventilation in Severe Acute Brain Injury• The priority is cerebral resuscitation and maintaining cerebral perfusion pressure.• Ventilation strategy must maintain adequate oxygenation and prevent hypercapnia or hypocapnia.Brain-Protective Ventilation Principles• Maintain PaCO₂ between 35–40 mmHg to prevent secondary brain injury.• Maintain SpO₂ ≥ 94% with FiO₂ titrated to avoid hyperoxia.• Keep MAP > 80 mmHg to support cerebral perfusion.• Use deep sedation and analgesia to prevent coughing, straining, or rising ICP.✧ Suggested Ventilator Settings (Initial RSI)• Mode: Volume control or SIMV• FiO₂: 100% initially, then titrate to maintain SpO₂ > 94%• Tidal Volume: 6–8 mL/kg ideal body weight• PEEP: 5 cmH₂O (avoid high PEEP which increases ICP)• Respiratory Rate: 18–22/min to target PaCO₂ 35–40 mmHg• I:E Ratio: 1:2• Sedation: Propofol, fentanyl, ± paralytics if ICP control requiredSevere Metabolic Acidosis Major Ventilation Danger in Metabolic Acidosis• The patient is compensating by hyperventilating and blowing off CO₂.• Intubation causes brief apnea, which makes PaCO₂ rise sharply, worsening acidosis and risking cardiac arrest.Targets Before Intubation• Increase RR using NIV if possible.• Minimize apnea duration.• Most experienced operator should perform RSI.Winter’s Formula (Gold Standard)Predicted PaCO₂ = 1.5 × HCO₃ + 8 ± 2• If actual PaCO₂ is higher, there is additional respiratory acidosis, requiring increased minute ventilation.• If actual PaCO₂ is lower, additional respiratory alkalosis is present.
9EVeC 2025 I Negeri Sembilan Emergency Ventilator Course38Post-Intubation Ventilation Strategy• Aim to match pre-intubation minute ventilation to avoid acute CO₂ rise.• Use high respiratory rate (initial RR 28–35/min).• Keep TV 8 mL/kg ideal body weight.• Increase flow rate to 60 L/min to allow rapid inspiration and longer expiration.• Watch for auto-PEEP when RR > 30/min.Practical Initial Settings (SIMV Volume Control)• FiO₂: 100% initially• TV: 8 mL/kg IBW• PEEP: 5• PS: 5–10• Flow rate: 30–60 L/min• RR: 30 (adjust based on PaCO₂)• I:E: 1:2 or 1:3ABG Target Correction• If PaCO₂ > predicted (Winter formula) →Increase minute ventilation (RR ↑).• If PaCO₂ < predicted →Reduce RR to avoid alkalosis and worsening intracellular acidosis.Cardiac Arrest VentilationKey Principles• Maintain oxygenation and ventilation without interfering with CPR and cardiac output.• Avoid auto-triggering and minimize airway pressure during compressions.Ventilation Settings During CPR• FiO₂: 100%• TV: 8 mL/kg• PEEP: 5 cmH₂O to allow venous return• Respiratory Rate: 10/min• I:E Ratio: 1:5 (Ti 1 sec)• Pmax alarm: 60 cmH₂O• Trigger: Off (to prevent ventilator cycling due to chest compression recoil)Rationale• Low RR prevents increasing intrathoracic pressure during chest compressions.• Trigger OFF prevents “false triggering” from chest wall movement.• PEEP of 5 supports oxygenation but avoids venous return impairment.