Mechanical ventilation
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Mechanical ventilation

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    Mechanical ventilation Mechanical ventilation Presentation Transcript

    • MECHANICAL VENTILATION Marc Charles Parent
    • Presentation
      • Different settings to consider
      • Monitoring of the patient
      • Different type of patient
        • COPD, Asthma
        • ARDS
      • Trouble shooting
    • Ventilator settings
    • Ventilator settings
      • Ventilator mode
      • Respiratory rate
      • Tidal volume or pressure settings
      • Inspiratory flow
      • I:E ratio
      • PEEP
      • FiO2
      • Inspiratory trigger
    • 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.
    • Respiratory Rate
      • What is the pt actual rate demand?
    • Tidal Volume or Pressure setting
      • Maximum volume/pressure to achieve good ventilation and oxygenation without producing alveolar overdistention
      • Max cc/kg? = 10 cc/kg
      • Some clinical exceptions
    • Inspiratory flow
      • Varies with the Vt, I:E and RR
      • Normally about 60 l/min
      • Can be majored to 100- 120 l/min
    • I:E Ratio
      • 1:2
      • Prolonged at 1:3, 1:4, …
      • Inverse ratio
    • FIO2
      • The usual goal is to use the minimum Fio2 required to have a PaO2 > 60mmhg or a sat >90%
      • Start at 100%
      • Oxygen toxicity normally with Fio2 >40%
    • Inspiratory Trigger
      • Normally set automatically
      • 2 modes:
        • Airway pressure
        • Flow triggering
    • Positive End-expiratory Pressure (PEEP)
      • What is PEEP?
      • What is the goal of PEEP?
        • Improve oxygenation
        • Diminish the work of breathing
        • Different potential effects
    • PEEP
      • What are the secondary effects of PEEP?
        • Barotrauma
        • Diminish cardiac output
        • Regional hypoperfusion
        • NaCl retention
        • Augmentation of I.C.P.?
        • Paradoxal hypoxemia
    • PEEP
      • Contraindication:
        • No absolute CI
        • Barotrauma
        • Airway trauma
        • Hemodynamic instability
        • I.C.P.?
        • Bronchospasm?
    • PEEP
      • What PEEP do you want?
        • Usually, 5-10 cmH2O
    • Monitoring of the patient
    • Look at your patient
      • Question your pt
      • Examine your pt
      • Monitor your pt
      • Look at the synchronicity of your pt breathing
    • Pressures
    • Compliance pressure (Pplat)
      • Represent the static end inspiratory recoil pressure of the respiratory system, lung and chest wall respectively
      • Measures the static compliance or elastance
    • Pplat
      • Measured by occluding the ventilator 3-5 sec at the end of inspiration
      • Should not exceed 30 cmH2O
    • Peak Pressure (Ppeak)
      • Ppeak = Pplat + Pres
      • Where Pres reflects the resistive element of the respiratory system (ET tube and airway)
    • Ppeak
      • Pressure measured at the end of inspiration
      • Should not exceed 50cmH2O?
    • Auto-PEEP or Intrinsic PEEP
      • What is Auto-PEEP?
        • Normally, at end expiration, the lung volume is equal to the FRC
        • When PEEPi occurs, the lung volume at end expiration is greater then the FRC
    • Auto-PEEP or Intrinsic PEEP
      • Why does hyperinflation occur?
        • Airflow limitation because of dynamic collapse
        • No time to expire all the lung volume ( high RR or Vt)
        • Expiratory muscle activity
        • Lesions that increase expiratory resistance
    • Auto-PEEP or Intrinsic PEEP
      • Auto-PEEP is measured in a relaxed pt with an end-expiratory hold maneuver on a mechanical ventilator immediately before the onset of the next breath
    • Auto-PEEP or Intrinsic PEEP
      • Adverse effects:
        • Predisposes to barotrauma
        • Predisposes hemodynamic compromises
        • Diminishes the efficiency of the force generated by respiratory muscles
        • Augments the work of breathing
        • Augments the effort to trigger the ventilator
    • Different types of patient
    • COPD and Asthma
      • Goals:
        • Diminish dynamic hyperinflation
        • Diminish work of breathing
        • Controlled hypoventilation (permissive hypercapnia)
    • Diminish DHI
      • Why?
    • Diminish DHI
      • How?
        • Diminish minute ventilation
          • Low Vt (6-8 cc/kg)
          • Low RR (8-10 b/min)
          • Maximize expiratory time
    • Diminish work of breathing
      • How:
        • Add PEEP (about 85% of PEEPi)
        • Applicable in COPD and Asthma.
    • Controlled hypercapnia
      • Why?
        • Limit high airway pressures and thus diminish the risk of complications
    • Controlled hypercapnia
      • How?
        • Control the ventilation to keep adequate pressures up to a PH > 7.20 and/or a PaCO2 of 80 mmHg
    • Controlled hypercapnia
      • CI:
        • Head pathologies
        • Severe HTN
        • Severe metabolic acidosis
        • Hypovolemia
        • Severe refractory hypoxia
        • Severe pulmonary HTN
        • Coronary disease
    • A.R.D.S.
      • Ventilation with lower tidal volume as compared with traditional volumes for acute lung injury and the ARDS
      • The Acute Respiratory Distress Syndrome Network
      • N Engl J Med 2000;342:1301-08
    • Methods
      • March 96 – March 99
      • 10 university centers
      • Inclusion:
        • Diminish PaO2
        • Bilateral infiltrate
        • Wedge < 18
      • Exclusion
      • Randomized
    • Methods
      • A/C 28d or weaning
      • 2 groups:
        • 1. Traditional Vt (12cc/kg)
        • 2. Low Vt (6cc/kg)
      • End point:
        • 1. Death
        • 2. Days of spontaneous breathing
        • 3. Days without organ failure or barotrauma
    • Results
      • The trails were stopped after 861 pt because of lower mortality in low Vt group
    • Trouble Shooting
    • Trouble Shooting
      • Doctor, doctor, his pressures are going up!!!
      • What is your next step?
    • Trouble Shooting
      • Call the I.T., he will take care of it!
      • Where is the staff?
      • I dont know this pt, and run!
      • Ask which pressure is going up
    • Trouble Shooting
      • Ppeak is up
        • Look at your Pplat
    • Trouble Shooting
      • If your Pplat is high, you are faced with a COMPLIANCE problem
      • If your Pplat is N, you are faced with a RESISTIVE problem
      • DD?
    • Trouble Shooting
    • Trouble Shooting
      • Doctor, doctor, my patient is very agitated!
        • What is your next step?
    • Trouble Shooting
      • Give an ativan to the nurse!
      • Give haldol 10mg to the patient!
      • Take 5mg of morphine for yourself!
      • Look at your pt!
    • Trouble Shooting
      • At the time of intubation, fighting is largely due to anxiety
      • But what do you do if pt is stable and then becomes agitated?
    • Trouble Shooting
      • Remove pt from ventilator
      • Initiate manual ventilation
      • Perform P/E and assess monitoring indices
      • Check patency of airway
      • If death is imminent, consider and treat most likely causes
      • Once pt is stabilized, undertake more detailed assessement and management
    • Trouble Shooting
    • Conclusion