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Andrea Vianello S.C. Fisiopatologia Respiratoria Ospedale-Università di Padova QUANDO VENTILARE? CON COSA VENTILARE?

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Presentation on theme: "Andrea Vianello S.C. Fisiopatologia Respiratoria Ospedale-Università di Padova QUANDO VENTILARE? CON COSA VENTILARE?"— Presentation transcript:

1 Andrea Vianello S.C. Fisiopatologia Respiratoria Ospedale-Università di Padova QUANDO VENTILARE? CON COSA VENTILARE?

2 RESPIRATORY FAILURE LUNG FAILURE PUMP FAILURE GAS EXCHANGE FAILURE VENTILATORY FAILURE HYPOXEMIA HYPERCAPNIA

3 Whats the point of ventilation? –Deliver O 2 to alveoli Hb binds O 2 (small amount dissolved) CVS transports to tissues to make ATP - do work –Remove CO 2 from pulmonary vessels from tissues - metabolism

4 To maintain or improve ventilation, & tissue oxygenation. To decrease the work of breathing & improve patients comfort. Why ventilate?- purposes

5 When ventilate?- indications Failure of pulmonary gas exchange –Hypoxaemia: low blood O 2 Mechanical failure –Hypercarbia: high blood CO 2 – Respiratory muscle fatigue Need to intubate eg patient unconscious Others eg –need neuro-muscular paralysis to allow surgery –cardiovascular reasons

6 Non-Invasive Ventilation a form of ventilatory support that avoids airway invasion Hill et al Crit Care Med 2007; 35:2402-7

7 Paziente con riacutizzazione acidotica di BPCO Terapia medica + O 2 q.b. per SpO %

8 Airway Inflammation Airway narrowing & obstruction Shortened muscles curvature Frictional WOB muscle strength V T PaCO 2 pH PaO 2 Gas trapping Auto- PEEP VCO 2 V E Elastic WOB V A

9 Airway Inflammation Airway narrowing & obstruction Shortened muscles curvature Frictional WOB muscle strength V T PaCO 2 pH PaO 2 Gas trapping Auto- PEEP VCO 2 V E Elastic WOB V A usa i farmaci e bene ! Steroids Abx BDs Teophylline

10 Airway Inflammation Airway narrowing & obstruction Shortened muscles curvature Frictional WOB muscle strength V T PaCO 2 pH PaO 2 Gas trapping Auto- PEEP VCO 2 V E Elastic WOB V A Steroids Abx BDs Teophylline MV PEEP usa i farmaci e bene !

11 Paziente con riacutizzazione acidotica di BPCO Terapia medica + O 2 q.b. per SpO % Ripetizione di EGA NIV non indicata pH > 7.35>7.30 pH < 7.35 pH < 7.30 pH < 7.20

12 NIV consigliata l80% dei pazienti migliora comunque con terapia standard Ogni 10 pazienti trattati con NIV si evita 1 ETI; NIV migliora la dispnea NIV altamente consigliata Senza NIV 1 paziente su 2 necessita di ETI NIV migliora la sopravvivenza NIV altamente consigliata 1 paziente su 2 fallisce NIV Tuttavia con NIV migliora outcome ospedaliero e sopravvivenza a 1 anno > 7.30 pH < 7.35 pH < 7.30 pH < 7.20

13 NIV VS TRATTAMENTO STANDARD Keenan S et al

14 NIV VS TRATTAMENTO STANDARD Keenan S et al

15 NIV VS TRATTAMENTO STANDARD Keenan S et al

16 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: Girou et al JAMA 2000; 284:2361-7

17 2005; 128

18 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 inferiorecon NIV 48% evitano ETI, sopravvivono con permanenza in ICU inferiore vs 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%)

19 Studio caso-controllo: 64 paz. con IRA trattati con NIV pH = /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) migliore sopravvivenza e ridotta permanenza in ICUSe NIV efficace (24/64 = 38%) migliore sopravvivenza e ridotta permanenza in ICU vs pazienti VM invasiva NIV riduce necessità di ETI e ospedalizzazione, migliora outcome a lungo termine

20 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

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22 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

23 Several ways to connect the machine to patient Oro-tracheal Intubation Tracheostomy Non-Invasive Ventilation

24 Normal breath inspiration, awake Diaphragm contracts Chest volume Pleural pressure Air moves down pressure gradient to fill lungs -2cm H cm H20 Alveolar pressure falls Normal breath FRC= balance

25 La pompa diaframmatica genera P garantendo la ventilazione polmonare, regolata da: Equazione di moto del Sistema Respiratorio: Pmusc = V / C + V x R

26 Normal breath expiration, awake Diaphragm relaxes Pleural / Chest volume Pleural pressure rises Normal breath Alveolar pressure rises Air moves down pressure gradient out of lungs -7cm H20 -2cm H 2 0

27 Portable ventilator ICU ventilator Ventilator breath

28 Ventilator breath inspiration Air blown in lung pressure Air moves down pressure gradient to fill lungs Pleural pressure 0 cm H to+10 cm H 2 0 Ventilator breath

29 Il ventilatore sostituisce totalmente o parzialmente la pompa muscolare: Equazione di moto del Sistema Respiratorio: Pappl (+ Pmusc) = V / C + V x R

30 Ventilator breath expiration Similar to spontaneous…ie passive Ventilator stops blowing air in Pressure gradient Alveolus-trachea Air moves out Down gradient Lung volume Ventilator breath

31 Practicalities Ventilator settings: Pressure vs volume Assist vs Control Trigger sensitivity PEEP?

32 Details: Inspiration Pressure or Volume? Do you push in.. –A gas at a set pressure? = pressure….. –A set volume of gas? = volume….

33 TimePressure cm H 2 0 TimePressure cm H 2 0 Details: Inspiration Pressure or Volume?

34 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 patients inspiratory flow demand throughout inspiration, patient effort is reduced and comfort increased. Pressure Ventilators

35 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.

36 Details: Inspiration Pressure or Volume?

37 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. The amount of pressure required to deliver the set volume depends on : - Patients lung compliance - Patient–ventilator resistance factors Volume Ventilators

38 30 Time (s) aw P cmH 2 O Peak Inspiratory Pressure 3 Peak Inspiratory Pressure (PIP ) must be monitored in volume modes because it varies from breath to breath

39 Schönhofer ERS Monograph 2001; 16: , mod hypoventilation partial compensation sensitiveinsensitive Secretionshypoventilation Vt preserved Details: Pressure vs Volume in the Acute Setting

40 Vol Pressure without leakagewith leakage small leak huge leak Mehta et al. Eur Respir J 2001; 17: Pre-set Details: leak compensation

41 Respiratory muscle pump Ventilator Interaction

42 Respiratory muscle pump Ventilator work of breathing spontaneous assistedcontrolled..

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44 Noninvasive mechanical ventilation in acute exacerbation of restrictive thoracic disease Eur Respir Mon 2001; 6:70-73

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46 Nilsestuen et al. Respir Care 2005; 50: Inspiratory triggering 2.Inspiration 3.Termination of inspiration 4.Expiration 4 Phases Pressure Flow Volume Time

47 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 Details: trigger sensitivity

48 Trigger poco sensibile: allo sforzo inspiratorio non segue latto meccanico del respiratore

49 Trigger troppo sensibile: latto meccanico si innesca spontaneamente

50 Pao Pes patient 1 patient 2 patient 3

51 Asynchrony between patient and ventilator Problems: Increased work of breathing Need for sedation Fighting the ventilator Ventilation-Perfusion-Mismatch Dynamic hyperinflation Consequences: Insufficient ventilation Withdrawal from NIV Weaning failure Prolonged ICU stay Costs Prognosis !

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53 Loperatore imposta: Loperatore imposta: PSV Caratteristiche: - pressure-controlled - flow-cycled - patient-triggered - pressione inspiratoria - sensibilità trigger - eventuale rampa (tempo di raggiungimento PS) - > sincronismo paziente-ventilatore > comfort - possibile graduazione sforzo inspiratorio

54 lenta media rapida Diversi tipi di rampa

55 PSV PSV Problemi: - difficoltà di impostazione - livello PS V T : 6-8ml/Kg; RR: 20-35b/min P 0.1 : 2-4 cm H 2 O abolizione dissincronismi toraco- addominali - possibile sovrassistenza

56 Loperatore imposta: Loperatore imposta: A-CV Caratteristiche: -volume-controlled -time-cycled -machine e/o patient-triggered (assistito) -pressure-limited (eventuale) -volume corrente -frequenza respiratoria -rapporto I/E -sensibilità del trigger Problemi: - possibile sovrassistenza alcalosi respiratoria - insorgenza di PEEP intrinseca - volume corrente insufflato garantito - rapporto I/E variabile

57 A-CV

58 Hybrid modes combine the advantages of pressure pre-set and volume pre-set VAPS Volume Assured Pressure Support Automatic adjustment of inspiratory pressure (range setting) Target volume set Measurement of inspiratory pressure and expiratory volume Calculation of missing inspiratory volume Increase of inspiratory pressure Assurance of tidal volume + comfort of pressure pre-set

59 VAPS Volume Assured Pressure Support

60 VAPS Volume Assured Pressure Support

61 Storre et al. Chest 2006;130:

62 AVAPS provides elegant adjustments of inspiratory pressures according to a pre-set target volume AVAPS improves quality of ventilation Improvements of sleep quality and quality of life are comparable to BiPAP-S/T However: Sleep quality is not completely normalized Further studies are needed

63 Efficacy and comfort of Volume-Guaranteed Pressure Support (PSV-VTG) in patients with chronic ventilatory failure of neuromuscular origin

64

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66 Four types of asynchronies: Ineffective inspiratory effort (IE): thoraco- abdominal displacements not assisted by the ventilator positive pressure boost; Inspiratory trigger delay: a time lag between the initiation of the patents IE and the onset of inspiratory support; Prolonged inspiration or late expiratory cycling (hang-up): prolongation of mechanical insufflation beyond the end of patient inspiration; Autotriggering: rapid succession of at least three pressurizations at a RR of >40 br/min.

67 Efficacy and comfort of Volume-Guaranteed Pressure Support (PSV-VTG) in patients with chronic ventilatory failure of neuromuscular origin

68 Time Pressure cm H 2 0 Details: PEEP? PEEP Positive End Expiratory Pressure

69 Effects of PEEP Normal, Awake –in expiration alveoli do not close (closing capacity) –change size Lying down / Paralysis / +- pathology –Lungs smaller, compressed –Harder to distend, starting from a smaller volume –In expiration alveoli close (closing capacity) PEEP –Keeps alveoli open in expiration –Danger: applied to all alveoli –Start at higher point on compliance curve

70 Effects of PEEP Volume Pressure Compliance= Volume Pressure energy needed to open alveoli ?damaged during open/closing - abnormal forces over-distended alveoli

71 Effects of PEEP Volume Pressure Compliance= Volume Pressure Raised PEEP PEEP: start inspiration from a higher pressure ?damage during open/closing

72 Regional ventilation: PEEP Volume Pressure Compliance= Volume Pressure over-distended alveoli Spontaneous, standing

73 Regional ventilation: PEEP Volume Pressure Compliance= Volume Pressure Mechanical Ventilation

74 Details: Cardiovascular effects Compresses Pulmonary vessels Reduced RV outflow Reduced LV inflow

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78 Details: Cardiovascular effects Compresses Pulmonary vessels Reduced LV inflow – Cardiac Output: Stroke Volume –Blood Pressure = CO x resistance – Blood Pressure –Neurohormonal Reduced RV outflow- backtracks to body –Head- Intracranial Pressure –Others - venous pressure

79 Vent settings to improve Vent settings to improve PEEP Increases FRC Prevents progressive atelectasis and intrapulmonary shunting Prevents repetitive opening/closing (injury) Recruits collapsed alveoli and improves V/Q matching Resolves intrapulmonary shunting Improves compliance Enables maintenance of adequate P a O 2 at a safe FiO 2 level Disadvantages Increases intrathoracic pressure (may require pulmonary a. catheter) Rupture: PTX, pulmonary edema

80 Clinical Auto-PEEP Cardiogenic pulmonary edema ( LV preload) Hypoxemia with FIO2 > 0.5 Collapsing alveoli (ARDS, postop atelectasis) Chest wall instability (chest trauma) Physiological PaO2 < 60 mm Hg on FIO2 0.8 PaO2 < 10 mm Hg with FIO2 F of 0.2 PA-aO2 > 300 on FIO2 1.0 Shunt > 30% PEEP: Indications

81 NIV treatment: summary The ventilator management of NIV is continuously evolving; New ventilators are introduced, offering novel features; Clinical applications have been expanding; Clinicians must make selections that best match the ventilator with the patients requirements.


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