Mechanical ventilator


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Mechanical ventilator

  1. 1. Mechanical ventilator Rintu alphi tom suchithra.p.v
  2. 2. • 65 yr old male Mr. Vijayan • DOA- 10/09/2013 • Chief complaints : generalized weakness, acute exacerbation of breathlessness • Diagnosis : COPD, cor- pulmonale • Intervention : intubated and connected to mechanical ventilator
  3. 3. Mechanical ventilation • Mechanical ventilation is the process by which the fraction of inspired oxygen (FIO2) is at 21%(room air) or greater and moved into and out of the lungs by a mechanical ventilator.
  4. 4. Mechanical ventilation • Mechanical ventilation is the use of a ventilator to move room air or oxygen enriched air into and out of the lungs mechanically to maintain proper levels of oxygen and carbon dioxide in the blood
  5. 5. • The Roman physician Galen may have been the first to describe mechanical ventilation History
  6. 6. Negative-pressuare ventilators (“iron lungs”) first used in Boston Children’s Hospital in 1928 used extensively during polio outbreaks in 1940s – 1950s
  7. 7. Iron Lungs
  8. 8. History • Vesalius is credited with the first description of positive pressure ventilation
  9. 9. • In boston, the nearby emerson company made available a prototype positive pressure lung inflation device, which was put to use at the Massachusetts General Hospital, and became an instant success.
  10. 10. Positive pressure ventilator
  11. 11. Modern ventilators
  12. 12. Indications of mechanical ventilation • • • • • • • Acute respiratory failure Apnoea or impending inability to breathe Severe hypoxia Respiratory muscle fatigue Cardiac Insufficiency Neurological problems Therapeutic and prophylatic
  13. 13. Clinical parameters • • • • • Respiratory Rate ˃ 40/min Tidal volume ˃5ml/min Vital capacity ˃15ml/kg PaO2 ˃50mm of Hg with FiO2 ˃ 0.60 PaCO2 ˃ 55mm of Hg with pH ˃7.25
  14. 14. Goals of mechanical ventilation • • • • Decrease work of breathing Increase alveolar ventilation Maintain ABG values within normal range Improve distribution of inspired gases
  15. 15. terminology • Independent variables :The parameters that are set by clinician • Dependent variables :The parameters measured by the ventilators
  16. 16. • Fraction of inspired oxygen (FiO2) The concentration of O in the inspired gas, usually between 0.21 (room air) and 1.0 (100% O )
  17. 17. • Tidal volume (VT) The amount of air delivered to the patient per breath. It is customarily expressed in milliliters. • A starting point for the VT setting is 8 to 10ml/kg of ideal weight
  18. 18. • Respiratory rate/frequency (f)  The number of breaths per minute. This can be from the ventilator, the patient, or both. The RR is set as near to physiological rates (14 to 20 breaths/min) as possible.
  19. 19. • Minute ventilation (V E) The product of V and respiratory frequency (VT• f). It is usually expressed in liters/minute.
  20. 20. • Exhaled Tidal Volume It is the amount of gas that comes out of the patients lungs on exhalation. This is the most accurate measure of the volume received by the patient  If the EVT deviates from the set VT by 50ml or more, troubleshoot the system to identify the source of gas loss.
  21. 21. • Inspiratory to Expiratory ratio The I:E ratio is usually set to mimic the pattern of spontaneous ventilation. Generally the I:E ratio is set at 1:2, that is 33% of the respiratory cycle is spent in inspiration and 66% in the expiratory phase.
  22. 22. • Inverse Inspiratory to Expiratory ratio I:E ratios such as 1:1,2:1 and 3:1 are called inverse I:E ratios Inverse I:E ratio allows unstable alveoli time to fill and also prevents collapse by shortened expiratory phase.
  23. 23. • Positive end-expiratory pressure (PEEP)  The amount of positive pressure that is maintained at end-expiration. Typical settings for PEEP are 5 to 20 cm H2O  PEEP increases oxygenation by preventing collapse of small airways It increases the functional residual capacity of the lungs
  24. 24. Auto PEEP • Auto PEEP is the spontaneous development of PEEP caused by gas trapping in the lung resulting from insufficient expiratory time and incomplete exhalation • Causes of auto PEEP formation include rapid RR, high VE demand, airflow obstruction and inverse I:E ratio ventilation. • Auto PEEP = Total PEEP - Set PEEP
  25. 25. • Sensitivity determines the amount of patient effort needed to initiate gas flow on a patient- initiated breath • If the sensitivity is set too low, the patient must generate more work to trigger gas flow. • If it is set too high, autocycling of the ventilator may occur, resulting in patient- ventilator dyssynchrony,
  26. 26.  There are two ways to initiate a ventilator-delivered breath:  Pressure triggering : ventilator-delivered breath is initiated if the demand valve senses a negative airway pressure deflection (generated by the patient trying to initiate a breath) greater than the trigger sensitivity. Usual setting is0.5-1.5 cm H2O • Flow-by triggering: a continuous flow of gas through the ventilator circuit is monitored. A ventilator-delivered breath is initiated when the return flow is less than the delivered flow, a consequence of the patient's effort to initiate a breath. Usual setting is 1-3L/min below baseline flow
  27. 27. Sigh • A sigh is a mechanically set breath with greater volume than the preset VT, usually 1.5 to 2 times the VT
  28. 28. • Peak airway pressure (Paw): The pressure that is required to deliver the VT to the patient. It has a unit of centimeters of water (cm H2O).
  29. 29. • Plateau pressure (Pplat): The pressure that is needed to distend the lung. This pressure can only be obtained by applying an endinspiratory pause. It also has a unit of cm H2O
  30. 30. • Peak inspiratory flow: The highest flow that is used to deliver VT to the patient during inspiratory phase. It is usually measured in liters/minute. Usual setting 40-80L/min.
  31. 31. • Mean airway pressure: The time-weighted average pressure during the respiratory cycle. It is expressed in cm H2O
  32. 32. Types of mechanical ventilation • Invasive ventilation or conventional mechanical ventilation (MV) and noninvasive ventilation (NIV) • Positive or negative pressure ventilation
  33. 33. invasive ventilation • Conventional mechanical ventilation is implemented once a cuffed tube is inserted into the trachea to allow conditioned gas (warmed, oxygenated, and humidified) to be delivered to the airways and lungs at pressures above atmospheric pressure.
  34. 34. Modes Of Mechanical Ventilation • Modes of mechanical ventilation are the techniques that the ventilator and patient work together to perform the respiratory cycle. • Volume modes • Pressure modes
  35. 35. Volume modes • Controlled Mandatory ventilation (CMV) • Assist Control Ventilation(ACV) • Synchronized Intermittent Mandatory Ventilation(SIMV)
  36. 36. controlled mandatoryventilation (CMV) • Breaths are delivered at a set rate per minute and a set tidal volume(Vt) , which are independent of the patient’s ventilatory effects. • Vt is delivered regardless of changes in lung compliance or resistance. • It is used when the patient has no drive to breath or is unable to breath spontaneously
  37. 37. Assist Control Ventilation(ACV) • A/C mode of ventilation delivers a preset number of breaths of a preset Vt • When the patient initiates a breath by exerting a negative inspiratory effort, the ventilator delivers an assisted breath of the preset VT. • The preset RR ensures that the patient receives adequate ventilation, regardless of spontaneous efforts • The patient can breathe faster than the preset rate but not slower.
  38. 38. Disadvantages ACV • Repiratory alkalosis may develop if the patient has a tendency to hyperventilate because of anxiety, pain or neurological factors. • Patient may rely on the ventilator and not attempt to initiate spontaneous breathing if ventilatory demands are met.
  39. 39. Nurses responsibility • Total RR, to determine whether the patient is initiating spontaneous breaths • PIP, to determine whether it is increasing( indicating a change in compliance or resistance) • Patient’s sense of comfort and synchronization with the ventilator and acid base status.
  40. 40. Synchronized Intermittent Mandatory Ventilation(SIMV) • The SIMV mode of ventilation delivers a set number of breaths of a set VT, and between these mandatory breaths the patient may initiate spontaneous breaths. • If the patient initiates a breath near the time a mandatory breath is due, the delivery of the mandatory breath is synchronized with the patient’s spontaneous effort to prevent patient ventilator dyssynchrony.
  41. 41. simv • SIMV is indicated when it is desirable to allow patients to breathe at their own RR and thus assist in maintaining a normal PaCo2,or when hyperventilation has occurred in the A/C mode. • SIMV mode helps to prevent respiratory muscle weakness associated with mechanical ventilation • Self regulates the rate and volume of spontaneous breath • It is used as a mode for weaning
  42. 42. Nurses responsibility • Monitor RR to determine whether the patient is initiating spontaneous breaths, and the patients ability to manage the WOB. • Assess PIP, patient’s sense of comfort and synchronization with the ventilator and acid base status.
  43. 43. • If the total RR increases, the VT of the spontaneous breaths is assessed for adequacy. A rising total RR may indicate that the patient is beginning to fatigue, resulting in a more shallow and rapid respiratory pattern and that may lead to atelectasis
  44. 44. Pressure modes Pressure- Controlled Ventilation • Continuous Positive Airway Pressure(CPAP) • Bi-Level positive airway pressure (BiPAP) • Pressure Support • Pressure Assist/ Control • Pressure- Controlled Inverse Ratio Ventilation
  45. 45. Pressure- Controlled Ventilation • Peak Inspiratory Pressure is predetermined, and the VT delivered to the patient varies based on the selected pressure and the compliance and resistance factors of the patient –ventilator system. • Patients with normal lung compliance and low resistance will have better delivery of VT for the amount of inspiratory pressure set.
  46. 46. • Advantage of pressure controlled modes is that the PIP can be reliably controlled for each breath the ventilator delivers. • A disadvantage is that hypoventilation and respiratory acidosis may occur since delivered VT varies.
  47. 47. Nurses responsibility • Careful attention must be given to the VT to prevent unplanned hyperventilation and hypoventilation
  48. 48. Continuous Positive Airway Pressure(CPAP) • CPAP is positive pressure applied throughout the respiratory cycle to the spontaneously breathing patient. • The patient must have a reliable respiratory drive and the patient performs all the WOB • provides pressure at end expiration, which prevents alveolar collapse and improves the functional residual capacity and oxygenation
  49. 49. Nurses responsibility • The ventilator is used to deliver CPAP during weaning the nurse can monitor the adequacy of the patient’s VT • Alarms should be set to detect EVT and apnea
  50. 50. Pressure Support • The patient’s spontaneous respiratory activity is augmented by the delivery of a preset amount of inspiratory positive pressure. • The positive pressure is applied throughout inspiration • There is no rate set on the ventilator the patient must generate each breath
  51. 51. • Typical level of pressure support ordered for the patient are 6 to 12 cm of H2O • Ps may be used as a stand alone mode or in combination with other modes • PS may also be used for weaning from mechanical ventilation
  52. 52. Pressure Assist/ Control • Mode of ventilation in which there is a set RR, and every breath is augmented by a set amount of inspiratory pressure • If the patient triggers additional breaths beyond the mandatory breaths, those breaths are augmented by the set amount of inspiratory pressure.
  53. 53. • There is no set VT • The typical pressure ranges from 15 to 25 cm H2O which is higher than a PS level
  54. 54. Nurses Responsibility • During P-A/C the nurse must be familiar with all the ventilator settings: the level of pressure, the set RR, the FiO2, and the level of PEEP • The nurse monitors the total RR to evaluate whether the patient is initiating spontaneous breaths and EVT for adequacy of volume.
  55. 55. Pressure- Controlled Inverse Ratio Ventilation • patient receives P-A/C ventilation and the ventilator is set to provide longer respiratory times • The I:E ratio is inversed to increase the mean airway pressure, open and stabilize the alveoli, and improve oxygenation • uncomfortable, the patient must be sedated and possibly paralyzed to prevent ventilator dyssynchrony and oxygen desaturation
  56. 56. Newer methods of ventilatory support
  57. 57. High frequency ventilation It uses breathing frequencies several fold higher than physiologic rates and employing tidal volumes near or less than anatomic space.
  58. 58. Different systems may be used to deliver HFV High Frequency Jet Ventilation(HFJV) A nozzle or injector directs a high velocity steam high into the of gas high into the endotracheal tube at rapid frequencies.
  59. 59. • High Frequency Oscillation(HFO)  Both inspiration and expiration are active  A volume of gas is delivered on the instroke and an equal volume of gas removed at the outstroke  Primarily used in infants
  60. 60. Bi-Level positive airway pressure (BiPAP) • Describes situation of two levels • Higher Inspiratory Positive Airway Pressure (IPAP) level and lower Expiratory Positive Airway Pressure(EPAP) ,along with oxygen • It is a non invasive modality and is delivered through a tight fitting face mask or nasal mask. • This may be used after extubation to prevent reintubation, COPD, heart failure
  61. 61. Airway Pressure- Release Ventilation(APRV) • It is a style of inverse ratio ventilation • Independent inspiratory(P High) and expiratory (PEEP) pressure • provides two levels of CPAP, one during inspiration and the other during expiration
  62. 62. Neurally Adjusted Ventilatory Assist • NAVA is adjusted by a computer (servo) and is similar to ATC but with more complex requirements for implementation. • In terms of patient-ventilator synchrony, NAVA supports both resistive and elastic work of breathing in proportion to the patient’s inspiratory effort
  63. 63. ECMO • veno-venous bypass through a membrane lung has been used to reduce ventilation requirements, thereby minimizing further ventilation induced lung damage and encouraging resolution of the lung injury.
  64. 64. Nitric oxide administration:• Having bronchodilator and pulmonary vasodilator effects • when delivered through the airways and has been shown to improve arterial oxygenation
  65. 65. Prone positioning • increases trans diaphragmatic pressures in the dependent regions of the lung • No need to apply additional airway pressure
  66. 66. Open lung ventilation (OLV) • Dynamic process of opening previously collapsed lung units by increasing trans pulmonary pressure. • Either volume cycled or pressure control ventilation. • Opening alveolar units by selecting a tidal volume and level of PEEP.
  67. 67. Liquid ventilation • It is a technique of mechanical ventilation in which the lungs are insufflated with an oxygenated perfluorochemical liquid rather than an oxygen-containing gas mixture
  68. 68. advantages • Reducing surface tension by maintaining a fluid interface with alveoli • Opening of collapsed alveoli by hydraulic pressure with a lower risk of barotrauma • Providing a reservoir in which oxygen and carbon dioxide can be exchanged with pulmonary capillary blood • Functioning as a high efficiency heat exchanger
  69. 69. Total liquid ventilation • The entire lung is filled with an oxygenated PFC liquid • A liquid tidal volume of PFC is actively pumped into and out of the lungs • A specialized apparatus is required to deliver and remove PFC tidal volume and to extracorporeally oxygenate and remove carbon dioxide from the liquid
  70. 70. Partial liquid ventilation • The lungs are slowly filled with a volume of PFC equivalent or close to the FRC during gas ventilation • By using a conventional gas ventilator the PFC within the lungs is oxygenated and carbon dioxide is removed
  71. 71. Noninvasive ventilation The delivery of mechanical ventilation without an artificial airway
  72. 72. Noninvasive ventilation Negative pressure ventilation Iron lung Cuirass Noninvasive Positive Pressure Ventilation(NPPV) CPAP PEEP
  73. 73. Negative pressure ventilation • Intermittent negative pressure around the chest wall causes the chest to be pulled outward. • This reduces the intrathoracic pressure. • Air rushes in via the upper airway, which is outside the sealed chamber. • Expiration is passive • similar to normal ventilation
  74. 74. cuirass
  75. 75. Contraindication • Cardiac or respiratory arrest • Severe encephalopathy • Severe gastro intestinal bleed • Hemodynamic instability • Unstable angina and myocardial infarction
  76. 76. Contraindication • Facial surgery or trauma • Upper airway obstruction • High risk aspiration • inability to protect airways • Inability to clear secretions
  77. 77. Noninvasive Positive Pressure Ventilation(NPPV) • Provided by using a tight-fitting face mask or nasal mask.
  78. 78. indications • Acute exacerbations of COPD • Hypoxemic respiratory failure • Extubated patients with some respiratory distress • Cardiogenic pulmonary edema • Obstructive sleep apnea
  79. 79. contraindications • Apnea • Cardiovascular instability • Claustrophobia • Somnolence • High aspiration risk • Viscous or copious secretions
  80. 80. contraindications • inability to clear secretions • recent facial or gastroesophageal surgery • craniofacial trauma • burns
  81. 81. Advantages • Complications associated with artificial airway are reduced, such as vocal cord injury and ventilator associated pneumonia • Sedation needs are less • During NPPV the patient can eat and speak, and is free from the discomfort of an artificial airway.
  82. 82. Nurses responsibility • Ensure the right size and type of mask is chosen • Monitor the mask and skin under the mask edges for signs of breakdown • The mouth and airway passages should be monitored for excessive drying, and a humidification system applied as indicated
  83. 83. Physiologic Changes
  84. 84. Safety and alarms Two important rules • An alarm should never be silenced until the cause has been investigated and corrected. • If the source of the alarm cannot be determined, disconnect the client from the ventilator and use a hand-held resuscitation bag for manual ventilation with 100% oxygen until the problem can be resolved
  85. 85. • Pressure alarms • Volume alarms • Apnea alarms
  86. 86. Pressure Alarms • They are triggered when there is increased airway resistance or decreased lung compliance. • Low pressure alarms and high pressure alarms
  87. 87. Volume alarms • Volume alarms are valuable for ensuring adequate alveolar ventilation, particularly in the patient receiving a pressure mode of ventilation
  88. 88. Apnea alarms • This alarm is very important when the patient is on a spontaneous breathing mode such as PS or CPAP, and no mandatory breaths are set
  89. 89. Concept Of Care Bundle • Maintain head of bed elevation at 30 to 45 degrees • Interrupt sedation each day to assess readiness to wean from ventilator • Provide prophylaxis for deep vein thrombosis • Administer medications for peptic ulcer disease prophylaxis
  90. 90. Ventilatory Management Of ARDS • A pressure targeted approach which limits tidal volume to 4 to 8 ml/kg and plateau pressure to 35 cm H2O or less • IRV is most frequently used as a salvage mode.
  91. 91. Ventilator Management Of Patients With Head Injury • Several patients may need hyperventilation to control acute increases in intracranial pressure(ICP). Hyperventilation reduces PaCO2 and causes a decrease in cerebral blood flow by inducing cerebral vasoconstriction due to changes in the pH of the CSF.
  92. 92. • Ventilator Management Of COPD