Aerosol therapy for mv patients by Bashaier A. Alyami


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Aerosol is providing a treatment via inhalation. It provide treatment locally with better actions and less side effect.

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Aerosol therapy for mv patients by Bashaier A. Alyami

  1. 1. Aerosol Therapy for Mechanically Ventilated Patients Done By : Bashaier A. Alyami
  2. 2. : Introduction Inhaled therapy has been routinely employed for over half a century in ambulatory patients with respiratory disorders. In contrast, many barriers were previously thought to preclude effective aerosol delivery in mechanically ventilated patients. The major barriers were : 1- the poor efficiency of aerosol-generating devices in ventilator circuits, 2- inadequate understanding of the factors influencing aerosol delivery during mechanical ventilation 3- mechanical ventilators that were not designed to optimize aerosol use.
  3. 3. Characteristics of Aerosol particles : 1. Particle size 2. Inertial Impaction 3. Gravitational Sedimentation 4. Diffusion 
  4. 4. : Devices used  - Nebulizers : Nebulizer performance varies with diluent volume, gas flow, density, operating pressure, and nebulizer model. During mechanical ventilation, nebulizers producing aerosols with MMADs of 1–3 µm are more likely to achieve deposition in the lower respiratory tract since larger particles impact on the ventilator circuit and endotracheal tube.
  5. 5. A common jet nebulizer system. An extrinsic gas flow, either from a compressed air source or from the ventilator passes through a Venturi and is accelerated leading to a pressure gradient that causes diluent/solubilized drug in the reservoir to be aerosolized and then entrained in .another stream of gas (tidal volume) going to the patient
  6. 6. A common ultrasonic nebulizer system . Ultrasonic waves of 1 MHz are applied to a reservoir of drug and diluent perturbing the liquid, leading to aerosolization and entrainment by the tidal Volume going to the patient.
  7. 7. . Cont  - Metered Dose Inhaler : The MDI canister contains a pressurized mixture of propellants, surfactants, preservatives, and flavoring agents, with ;1% of the total contents being active drug. The velocity of the liquid spray leaving the MDI is ;15 m/s, falling by 50% within 0.1 s as a cloud develops and moves away from the actuator orifice.
  8. 8. Factors influencing lower respiratory tract : deposition of aerosol * Ventilator/circuit-related factors Ventilator settings 1. Inspiratory flow rate 2. Respiratory rate 3. Tidal volume 4. Flow waveform 5. Ventilator cycling-volume vs pressure 6. Delivery by manual bag inflations
  9. 9. . Cont * Circuit determinants 1. Characteristics of the delivery device a. Nebulizer 1. Volume of fill 2. Frequency selection for ultrasonic devices 3. Specifications of the nebulizer device used, including MMAD 4. Flow rates for jet nebulization
  10. 10. . Cont b. MDI 1. Timing of the actuation 2. Spacer device 3. Actuator 4. Intra-ETT catheters
  11. 11. . Cont 2. Amount of drug administered 3. Humidification of inspired gases 4. Where in circuit MDI/nebulizer is administered 5. Length and diameter of ventilator tubing 6. Diameter and length of the ETT 7. Use of low-density gas (heliox)
  12. 12. . Cont * Patient-determined factors : Airway determinants 1. Bronchoconstriction 2. Secretions 3. Mucosal function Patient's effects on gas flow 1. Spontaneous respiratory pattern 2. Generation of intrinsic PEEP
  13. 13. Differences during MV : 1- Breath Configurations During controlled mechanical ventilation (CMV), the pattern and rate of inspiratory gas flow, as well as the rate and pattern of breathing, may differ from that during spontaneous respiration.
  14. 14. : The Airway- 2 The conduit between the aerosol device and the lower respiratory tract in mechanically ventilated patients is narrower than the oropharynx and has abrupt angles (eg, the 90degree connector often used to connect the ventilator circuit wye to the ETT), which result in points of impaction and turbulence that are not found in the normal airway.
  15. 15. . Cont While the ETT is narrower than the trachea, its smooth interior surface may create a more laminar-flow path than the structures of the glottis and be less of a barrier to aerosol delivery than the ventilator circuit.
  16. 16. The Environment- 3 Humidity has been shown to relate to an increase in particle size and reduced deposition during CMV, but no data exist to suggest that this reduction is unique to the ventilated patient.
  17. 17. : The Assessment- 4 The common method to assess patient response to bronchodilator administration is through changes in expiratory flow rates. Most investigators have relied on changes in the inspiratory airway resistance to quantitate a bronchodilator effect in mechanically ventilated patients.
  18. 18. : Aerosol Generating Devices Nebulizers : Alternatively, the air flow generated by a ventilator can be used to power the nebulizer during inspiration (intermittent operation). A separate line provides driving pressure and gas flow from the ventilator to a nebulizer connected in the ventilator circuit. However, the driving pressure provided by most ventilators to the nebulizer (<15 psi) is much lower than that provided by compressed air or oxygen sources commonly available in the hospital (≥ 50 psi).
  19. 19. Position and Method of Connecting the : Aerosol Generator in the Ventilator Circuit Placement of a nebulizer at a distance of 30 cm from the endotracheal tube is more efficient than placement between the patient Y and the endotracheal tube because the ventilator tubing acts as a spacer for the aerosol to accumulate between inspirations. Addition of a spacer between the nebulizer and the endotracheal tube further modestly increases aerosol delivery.
  20. 20. . Cont Metered Dose Inhaler : Both in vitro and in vivo studies have found that the combination of an MDI and a chamber device results in a four- to- six-fold greater delivery of aerosol than MDI actuation into a connector attached directly to the endotracheal tube or into an in-line device that lacks a chamber.
  21. 21. Collapsible spacer chamber Non-collapsible spacer chamber
  22. 22. : Aerosol Particle Size Deposition in the lower respiratory tract of mechanically ventilated patients is likely to be more efficient with devices that generate aerosols with a MMAD of 1–3 µm.
  23. 23. . Cont Endotracheal Tube : Smaller the size of ETT, greater the particle impaction (esp in pediatric ETT)
  24. 24. . Cont Heating and Humidity of inhaled gas : - Greater aerosol deposition in the ventilator circuit and ETT with heated and humidified gas - Both diminishes pulmonary deposition of aerosols ~40% .
  25. 25. Density of the Inhaled Gas : Inhalation of a less dense gas (ie, helium-oxygen [heliox]), decreases the turbulence associated with high inspiratory flow rates during mechanical ventilation. Preliminary reports indicate up to 50% increase in deposition of albuterol from an MDI during CMV of a simulated adult patient when breathing heliox compared to that while breathing air or oxygen.
  26. 26. : Ventilator settings and Modes For efficient aerosol delivery to the lower respiratory tract, the V T of the ventilator-delivered breath must be larger than the volume of the ventilator tubing and endotracheal tube. V T of ≥ 500 mL in adults are associated with adequate aerosol delivery (see Table 1), 19,25 but the higher pressures required to deliver a larger V T can be detrimental to the lungs.
  27. 27. Actuation of an MDI into a cylindrical spacer synchronized with inspiration resulted in ~ 30% greater efficiency of aerosol delivery compared actuation during expiration. - Albuterol deposition was up to 23% higher in vitro during simulated spontaneous breaths (continuous positive airway pressure) than with controlled breaths of equivalent V T .
  28. 28. : Administration of the Aerosol Therapy
  29. 29. : Facing disadvantages Nebulizers : 1. Contamination and VAP   Use of aerosol was one of the independent factor associated with VAP Need to be cleaned and disinfected to minimize the risk
  30. 30. 2. Difficulty triggering    In patient on PS mode, a –ve airway pressure must be generated before the ventilator deliver a breath A continuous-flow nebulizer between the patient and the sensor in the ventilator makes it more difficult for the patient to generate the –ve pressure May lead to under-ventilation of the patients
  31. 31. 3. Damage to expiratory transducer  In some ventilator brand only 3. Variable rate and particle size (depends on the brand) 4. Operational efficiency of nebulizer changes with the pressure of the driving gas and with different fill volumes
  32. 32. 6. FiO2 change 7. Increase tidal volume and/ or airway pressure 8. Cost  Time consuming (prepare the drug, disinfection…).  Purchasing the aerosol generating device.
  33. 33. : Advantages of MDIs  Decreased cost  Reliability of dosing  Ease of administration  Less personnel time  Freedom  The from contamination ventilator circuit need not be disconnected  Reduce VAP
  34. 34. Options of inhaled drug delivery during NIPPV  Remove patient from ventilator and administer drug by nebulizer or MDI  Administer nebulizer therapy inline with NIPPV  Administer MDI therapy inline with NIPPV
  35. 35. A 42-year-old intravenous drug user was transferred to the ward for noninvasive respiratory support after discharge from the intensive care unit, where she had been treated for . fungal pneumonia and septicemia
  36. 36. : Bronchodilator use  Based on the finding that aerosol deposition is lower in MV patients than in non-intubated patients  higher  So, dose of BD were recommended what is the precise dosing regimen ?
  37. 37. In general, significant BD effects occur after administration of 4 puffs albuterol with a MDI+spacer 2.5mg of albuterol with a standard nebulizer Potential side effects were increased if administrated higher doses
  38. 38.  Duration of action (e.g. Ventolin)  Ambulatory patients: 4-6hrs  Mechanical ventilated: 2-4hrs vs 4-6hrs  Ventilated patients need more frequent administration of BD (shortacting)  E.g. every 3-4 hrs
  39. 39. Thank you 