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Learn about the importance of ventilation, indications for ventilatory support, and non-invasive ventilation strategies for patients with respiratory failure. Explore the benefits and techniques of mechanical ventilation to improve gas exchange and oxygenation. Understand the key factors in managing lung failure and gas exchange abnormalities in patients with lung diseases. Discover how ventilation plays a crucial role in delivering oxygen to the tissues and removing carbon dioxide from the body. Stay informed about the latest evidence-based practices and treatment options for respiratory failure.
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QUANDO VENTILARE? CON COSA VENTILARE? Andrea Vianello S.C. Fisiopatologia Respiratoria Ospedale-Università di Padova
RESPIRATORY FAILURE LUNG FAILURE PUMP FAILURE GAS EXCHANGE FAILURE VENTILATORY FAILURE HYPERCAPNIA HYPOXEMIA
What’s the point of ventilation? • Deliver O2 to alveoli • Hb binds O2 (small amount dissolved) • CVS transports to tissues to make ATP - do work • Remove CO2 from pulmonary vessels • from tissues - metabolism
Why ventilate?- purposes • To maintain or improve ventilation, & tissue oxygenation. • To decrease the work of breathing & improve patient’s comfort.
When ventilate?- indications • Failure of pulmonary gas exchange • Hypoxaemia: low blood O2 • “Mechanical” failure • Hypercarbia: high blood CO2 • Respiratory muscle fatigue • Need to intubate eg patient unconscious • Others eg • need neuro-muscular paralysis to allow surgery • cardiovascular reasons
Non-InvasiveVentilation “a formofventilatorysupportthatavoidsairwayinvasion” Hill et al Crit Care Med 2007; 35:2402-7
Paziente con riacutizzazione acidotica di BPCO Terapia medica + O2 q.b. per SpO2 89-92%
VCO2 Airway narrowing & obstruction Airway Inflammation Frictional WOB Auto- PEEP Shortened muscles curvature Elastic WOB Gas trapping muscle strength VT VE VA • PaCO2 • pH • PaO2
VCO2 usa i farmaci e bene ! Airway narrowing & obstruction Airway Inflammation Steroids Frictional WOB Abx Auto- PEEP Shortened muscles curvature BDs Elastic WOB Gas trapping Teophylline muscle strength VT VE VA • PaCO2 • pH • PaO2
MV VCO2 usa i farmaci e bene ! Airway narrowing & obstruction Airway Inflammation Steroids Frictional WOB Abx PEEP Auto- PEEP Shortened muscles curvature BDs Elastic WOB Gas trapping Teophylline MV muscle strength VT VE MV VA • PaCO2 • pH • PaO2
Paziente con riacutizzazione acidotica di BPCO Terapia medica + O2 q.b. per SpO2 89-92% Ripetizione di EGA pH < 7.20 pH < 7.30 pH > 7.35 >7.30 pH < 7.35 NIV non indicata
NIV consigliata l’80% dei pazienti migliora comunque con terapia standard Ogni 10 pazienti trattati con NIV si evita 1 ETI; NIV migliora la dispnea >7.30 pH < 7.35 NIV altamente consigliata Senza NIV 1 paziente su 2 necessita di ETI NIV migliora la sopravvivenza pH < 7.30 NIV altamente consigliata 1 paziente su 2 fallisce NIV Tuttavia con NIV migliora outcome ospedaliero e sopravvivenza a 1 anno pH < 7.20
NIV VS TRATTAMENTO STANDARD Keenan S et al
NIV VS TRATTAMENTO STANDARD Keenan S et al
NIV VS TRATTAMENTO STANDARD Keenan S et al
The ICU studies Confirm the feasibility of NIV Confirm the effectiveness of NIV Selected patients / enthusiastic Units Reduced complications - particularly infectious 16% v 48% 1 ,18 v 60% 2 Reduce ICU / Hospital stay 23 v 35 days 1 , 9 v 15 days 2 • 1. Brochard et al NEJM 1995; 333:817-22 2. Girou et al JAMA 2000; 284:2361-7
49 pazienti con IRA in BPCO dopo fallimento terapia medica, pH 7.2 • Simili durata di permanenza in ICU, durata VM, complicanze generali, mortalità in ICU, e mortalità in ospedale • con NIV 48% evitano ETI, sopravvivono con permanenza in ICU inferiorevs pazienti VM invasiva (P=0.02) • A 1 anno: NIV inferiore riospedalizzazione (65% vs 100% P=0.016) e minor frequenza di riutilizzo supplemento di ossigeno (0% vs 36%)
Studio caso-controllo: 64 paz. con IRA trattati con NIV pH = 7.18 • 40/64 (62%) fallimento NIV (RR con NIV - 38%) • Simili mortalità in ICU, e mortalità in ospedale; durata di permanenza in ICU e post ICU, ma: • Inferiori complicanze (P=0.01) e probabilità di rimanenere in VM (P=0.056) • Se NIV efficace (24/64 = 38%) migliore sopravvivenza e ridotta permanenza in ICUvs pazienti VM invasiva NIV riduce necessità di ETI e ospedalizzazione, migliora outcome a lungo termine
Definition: What is it? • Mechanical Ventilation =Machine to ventilate lungs = move air in (+ out) • Several ways to..move air in (IPPV vs others) Intermittent Positive Pressure Ventilation
Definition: What is it? • Mechanical Ventilation =Machine to ventilate lungs = move air in (+ out) • Several ways to..move air in (IPPV vs others) Intermittent Positive Pressure Ventilation • Several ways to connect the ventilator to the patient
Several ways to connect the machine to patient • Oro-tracheal Intubation • Tracheostomy • Non-Invasive Ventilation
Normal breath Normal breath inspiration, awake Lung @ FRC= balance Diaphragm contracts -2cm H20 Chest volume Pleural pressure -7cm H20 Alveolar pressure falls Air moves down pressure gradient to fill lungs
La pompa diaframmatica genera Pgarantendo la ventilazione polmonare, regolata da: • Equazione di moto del Sistema Respiratorio: Pmusc = V / C + V’ x R
Normal breath Normal breath expiration, awake -7cm H20 Diaphragm relaxes Pleural / Chest volume Pleural pressure rises -2cm H20 Alveolar pressure rises Air moves down pressure gradient out of lungs
Ventilator breath Portableventilator ICU ventilator ICU ventilator
Ventilator breath Ventilator breath inspiration Air blown in 0 cm H20 lung pressure Air moves down pressure gradient to fill lungs +5 to+10 cm H20 Pleural pressure
Il ventilatore sostituisce totalmente o parzialmente la pompa muscolare: • Equazione di moto del Sistema Respiratorio: Pappl (+ Pmusc) = V / C + V’ x R
Ventilator breath Ventilator breath expiration Similar to spontaneous…ie passive Ventilator stops blowing air in Pressure gradient Alveolus-trachea Air moves out Down gradient Lung volume
Practicalities • Ventilator settings: • Pressure vs volume • ‘Assist’ vs ‘Control’ • Trigger sensitivity • PEEP?
Details: Inspiration Pressure or Volume? • Do you push in.. • A gas at a set pressure? = ‘pressure…..’ • A set volume of gas? = ‘volume….’
Details: Inspiration Pressure or Volume? Pressure cm H20 Time Pressure cm H20 Time
Pressure Ventilators • The use of pressure ventilators is increasing in critical care units. • A typical pressure mode delivers a selected gas pressure to the patient early in inspiration, and sustains the pressure throughout the inspiratory phase. • By meeting the patient’s inspiratory flow demand throughout inspiration, patient effort is reduced and comfort increased.
Although pressure is consistent with these modes, volume is not. • Volume will change with changes in resistance or compliance • Therefore, exhaled tidal volume is the variable to monitor closely. • With pressure modes, the pressure level to be delivered is selected, and with some mode options, rate and inspiratory time are preset as well.
Volume Ventilators • The volume ventilator has been historically used in critical care settings • A respiratory rate, inspiratory time, and tidal volume are selected for the mechanical breaths. • The basic principle of this ventilator is that a designated volume of air is delivered with each breath. • Theamount of pressure required to deliver the set volume depends on : - Patient’s lung compliance - Patient–ventilator resistance factors
Peak Inspiratory Pressure (PIP ) must be monitored in volume modes because it varies from breath to breath 30 Peak Inspiratory Pressure P aw Time (s) cmH2O 1 2 3 -10
Details: Pressure vs Volume in the Acute Setting Secretions hypoventilation Vt preserved partial compensation hypoventilation sensitive insensitive Schönhofer ERS Monograph 2001; 16: 259-73, mod
small leak huge leak Details: leak compensation without leakage with leakage Pressure Vol Pressure Vol Pre-set Mehta et al. Eur Respir J 2001; 17: 259-267
Interaction Ventilator Respiratory muscle pump
. . Ventilator Respiratory muscle pump work of breathing spontaneous assisted controlled
Noninvasive mechanical ventilation in acute exacerbation of restrictive thoracic disease Eur Respir Mon 2001; 6:70-73
Pressure Flow Volume Time 4 Phases • Inspiratory triggering • Inspiration • Termination • of inspiration • Expiration Nilsestuen et al. Respir Care 2005; 50:202-232
Details: trigger sensitivity trigger asynchrony insensitive trigger sensitive trigger auto- triggering • trigger sensitivity to low • high level of PSV • hypercapnic encephalopathy • sedation • sleep • intrinsic PEEP (COPD) • tubing obstruction • trigger sensitivity to high • resistance changes • tubing leakage • cardiac oscillation
Trigger poco sensibile: allo sforzo inspiratorio non segue l’atto meccanico del respiratore
Trigger troppo sensibile: l’atto meccanico si innesca spontaneamente
Pao Pes patient 3 patient 1 patient 2