Ventilatory support


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Control ventilation and ventilator setting

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  • Dr.Husni Ajaj
  • Ventilatory support

    1. 1. Ventilatory support
    2. 2. indication <ul><li>Acute respiratory failure </li></ul><ul><li>Respiratory pump failure </li></ul><ul><li>reduce central drive </li></ul><ul><li>mechanical defect of the chest </li></ul><ul><li>respiratory muscle fatigue </li></ul><ul><li>Inefficient gas exchange </li></ul><ul><li>Reduction in F.R.C </li></ul><ul><li>Mismatch and shunt </li></ul><ul><li>Airway protection </li></ul><ul><li>Support of respiratory system </li></ul>06/07/09 Dr.husni
    3. 3. <ul><li>ARDS , ALI </li></ul><ul><li>COPD </li></ul><ul><li>Bronchial asthma </li></ul><ul><li>Bronchopleural fistula </li></ul>
    4. 4. ARDS <ul><li>Acute onset </li></ul><ul><li>Hypoxia- PaO2/FiO2<200 </li></ul><ul><li>Bilateral infiltrates on CXR </li></ul><ul><li>Absence of left atrial hypertension </li></ul>Mortality - 26% to 74%
    5. 5. Eddy Fan, JAMA. 2005;294
    6. 6. “ baby lung” Eddy Fan, JAMA. 2005;294
    7. 7. Ventilation Induced Lung Injury <ul><li>Volutrauma – over distention of alveoli </li></ul><ul><li>Barotrauma – high inflation pressures </li></ul><ul><li>Atelectrauma - repetitive opening and closing of alveoli </li></ul><ul><li>Biotrauma - up-regulated cytokine release </li></ul><ul><li>Oxygen toxicity </li></ul>
    8. 9. Ventilation in ARDS <ul><li>Which mode? </li></ul><ul><li>How much FiO2? </li></ul><ul><li>How much PEEP? </li></ul><ul><li>How much VT? </li></ul><ul><li>Target? </li></ul><ul><li>What if refractory ARDS? </li></ul>
    9. 10. Clinical relevant information from key papers over the last decade: optimizing care in ALI/ARDS Solid proof – restrictive use of sedation – restrictive use of fluids – restrictive use of SG-catheters – use of lower tidal volumes No proof (yet?) – use of high PEEP – use of corticosteroids Speculative – anticoagulant strategies
    10. 11. How much FiO2? <ul><li>Least FiO2 to achieve Oxygenation goal </li></ul><ul><ul><li>PaO2 55–80 mm Hg </li></ul></ul><ul><ul><li>SpO2 88–95% </li></ul></ul><ul><li>FiO2 > 60% risk of oxygen toxicity. </li></ul>
    11. 12. Restrictive use of fluids ARDS Network. N EnglJ Med.2006; 354:2564
    12. 13. How much Tidal volume? ARDS Network <ul><li>Low tidal volume -31% </li></ul><ul><li>(6 mL/kg predicted body weight) </li></ul><ul><li>Conventional tidal volume -40% </li></ul><ul><li>(12 mL/kg) </li></ul>Mortality
    13. 14. Use of lower tidal volumes ARDS Network. N EnglJ Med. 2005;
    14. 20. PEEP <ul><li>Improves oxygenation by providing movement of fluid from the alveolar to the interstitial space, </li></ul><ul><li>Prevent cyclical alveolar collapse </li></ul><ul><li>Recruitment of small airways collapsed alveoli, </li></ul><ul><li>Increase in FRC </li></ul>
    15. 21. Open Lung Ventilation (OLV) <ul><li>Objective - maintenance of adequate oxygenation and avoidance of cyclic opening and closing of alveolar units by selecting a level of PEEP that allows the majority of units to remain inflated during tidal ventilation </li></ul>
    16. 22. PEEP…. <ul><li>The lower inflection point on the static pressure–volume curve represents alveolar opening (or “recruitment”). </li></ul><ul><li>“ optimal PEEP” - The pressure just above this point, is best for alveolar recruitment </li></ul><ul><li>usually 10 to 18 cm H2O </li></ul>
    17. 23. optimal PEEP J J Cordingley, Thorax 2002;57
    18. 24. How much PEEP? <ul><li>Low PEEP(8.3±3.2 cm of water) </li></ul><ul><li>High PEEP (13.2±3.5 cm) </li></ul><ul><li>No difference in outcomes if VT- 6ml/kg and Plat. Pressure <30cm </li></ul>N Engl J Med 2004;351
    19. 25. Protective lung ventilation protocol from the ARDSNet study <ul><li>Initial tidal volume – 6ml/kg </li></ul><ul><li>Plat. Pressure <30cm H 2 0 </li></ul><ul><li>Oxygenation goal PaO 2 = 55 - 80 mmHg or pulse oximetry oxygen saturation 88–95% </li></ul><ul><li>I:E ratio 1:1–1:3 </li></ul><ul><li>Goal arterial pH = 7.30–7.40  </li></ul><ul><ul><li>If pH < 7.30, increase respiratory rate up to 35 breaths/min  </li></ul></ul><ul><ul><li>If pH < 7.30 and respiratory rate = 35, consider starting intravenous bicarbonate </li></ul></ul>
    20. 26. Proven Therapeutic Strategies for ALI/ARDS No solid proof (yet) ARDS Network. N EnglJ Med.2004; 351:
    21. 27. Refractory hypoxia <ul><li>1. Neuromuscular blocking agents (if not already in use) </li></ul><ul><li>2. Prone position ventilation </li></ul><ul><li>3. Recruitment maneuvers </li></ul><ul><li>4. Inverse ratio ventilation, </li></ul><ul><li>5. Miscellaneous – </li></ul><ul><ul><li>nitric oxide, </li></ul></ul><ul><ul><li>high-frequency ventilation, </li></ul></ul><ul><ul><li>extracorporeal membrane oxygenation, or </li></ul></ul><ul><ul><li>partial liquid ventilation </li></ul></ul>
    22. 28. Prone position ventilation <ul><li>Improve oxygenation </li></ul><ul><ul><li>Better FRC </li></ul></ul><ul><ul><li>Recruitment of dorsal lung </li></ul></ul><ul><ul><li>Better clearance of secretion </li></ul></ul><ul><ul><li>Better ventilation-perfusion matching </li></ul></ul><ul><li>Potential problems </li></ul><ul><ul><li>facial oedema, eye damage </li></ul></ul><ul><ul><li>dislodgment of endotracheal tubes and intravascular catheters </li></ul></ul><ul><ul><li>Difficulty in resuscitation </li></ul></ul>No differences in clinical outcome
    23. 29. Proven–use of prone position GattinoniL. N EnglJ Med.2001; 345:
    24. 31. Sedation <ul><li>Ventilated patients generally require sedation to tolerate both ventilation and the presence of an endotracheal tube. </li></ul><ul><li>Assessment of sedation </li></ul><ul><li>+ 3 Agitated and restless </li></ul><ul><li>+ 2 Awake and uncomfortable </li></ul><ul><li>+ 1 Aware but calm </li></ul><ul><li>0 Roused by voice </li></ul><ul><li>- 1 Roused by touch </li></ul><ul><li>- 2 Roused by painful stimuli </li></ul><ul><li>- 3 Cannot be roused </li></ul><ul><li>A Natural sleep </li></ul><ul><li>P Paralysed </li></ul>
    25. 32. Solid proof –restrictive use of sedation “ daily interruption”shortens duration of MV, also in patients with ALI/ARDS” Kress JP N EnglJ Med.2000; 342:1471
    26. 34. Recruitment manoeuvres <ul><li>Sigh function in ventilators </li></ul><ul><li>By ambu bag </li></ul><ul><li>Sustained inflation or CPAP of 30-45 cm H 2 0 for 20-120 sec. </li></ul>
    27. 35. Inverse ratio ventilation <ul><li>Prolongation of the inspiratory time as a method of recruitment </li></ul><ul><li>Pressure control ventilation to increase the I:E ratio to 1:1 or 2:1 </li></ul><ul><li>hyperinflation and the generation of intrinsic PEEP </li></ul>
    28. 36. Physiotherapy <ul><li>Patients who are intubated cannot clear secretions effectively because of reduced conscious level, poor cough effort, and discomfort. Regular chest physiotherapy and tracheal suction are essential. </li></ul>
    29. 38. Position <ul><li>Regular turning to avoid pressure sores also helps mobilize and clear secretions. </li></ul>
    30. 39. Pharmacological adjuncts <ul><li>Inhaled nitric oxide may improve oxygenation by dilating pulmonary vessels passing alongside ventilated alveoli. </li></ul>
    31. 40. <ul><li>The results of blood gas analysis alone are rarely sufficient to determine the need for mechanical ventilation. </li></ul><ul><li>Several other factors have to be taken into consideration: </li></ul>
    32. 41. <ul><li>Degree of respiratory work— </li></ul><ul><li>Likely normal blood gas tensions for that patient— </li></ul><ul><li>Likely course of disease— </li></ul><ul><li>Adequacy of circulation - </li></ul>
    33. 42. Degree of respiratory work <ul><li>A patient with normal blood gas tensions who is working to the point of exhaustion is more likely to need ventilating than one with abnormal tensions who is alert, oriented, talking in full sentences, and not working excessively. </li></ul>
    34. 43. Likely normal blood gas tensions for that patient <ul><li>Some patients with severe chronic lung disease will lead surprisingly normal lives with blood gas tensions which would suggest the need for ventilation in someone previously fit. </li></ul>
    35. 44. Likely course of disease <ul><li>If imminent improvement is likely ventilation can be deferred, although such patients need close observation and frequent blood gas analysis. Adequacy of circulation—A patient with established or threatened circulatory failure as well as respiratory failure should be ventilated early in order to gain control of at least one major determinant of tissue oxygen delivery. </li></ul>
    36. 45. Adequacy of circulation <ul><li>— A patient with established or threatened circulatory failure as well as respiratory failure should be ventilated early in order to gain control of at least one major determinant of tissue oxygen delivery. </li></ul>
    37. 47. Peripheral cyanosis and poor capillary refill indicate failing circulation
    38. 49. Indicators of respiratory distress <ul><li>x Tachypnoea, dyspnoea </li></ul><ul><li>x Sweating </li></ul><ul><li>x Tachycardia and bounding pulse </li></ul><ul><li>x Agitation, restlessness, diminished conscious level, unwilling to lie flat </li></ul><ul><li>x Use of accessory muscles, intercostal recession </li></ul><ul><li>x Abdominal paradox (abdomen moves inward during inspiration) </li></ul><ul><li>x Respiratory alternans (thoracic movement then abdominal movement) </li></ul><ul><li>x Cyanosis or pallor </li></ul>
    39. 50. Ventilator strategy <ul><li>The choice of ventilatory mode and settings </li></ul><ul><li>tidal volume, </li></ul><ul><li>respiratory rate, </li></ul><ul><li>positive end expiratory pressure (PEEP), </li></ul><ul><li>ratio of inspiratory to expiratory time depends on the patient’s illness. </li></ul><ul><li>Damage to lungs can be exacerbated by mechanical ventilation, possibly because of over distension of alveoli and the repeated opening and collapse of distal airways. </li></ul>
    40. 51. Methods of ventilation <ul><li>No consensus exists on the best method of ventilation. </li></ul><ul><li>In volume controlled methods the ventilator delivers a preset tidal volume. The inspiratory pressure depends on the resistance and compliance of the respiratory system. </li></ul><ul><li>In pressure controlled ventilation the delivered pressure is preset. Tidal volume varies according to the resistance and compliance of the respiratory system. </li></ul>
    41. 52. <ul><li>Pressure controlled ventilation has become popular for severe acute respiratory distress syndrome as part of the lung protective strategy. </li></ul><ul><li>As well as limiting peak airway pressure, </li></ul><ul><li>the distribution of gas may be improved within the lung. </li></ul><ul><li>Pressure controlled ventilation is often used with a long inspiratory phase (inverse ratio ventilation) to maintain adequate alveolar recruitment. </li></ul>
    42. 53. Which mode? <ul><li>Volume assist/control commonly used </li></ul><ul><li>Plateau-pressure goal ≤30 cm of water </li></ul>ARDS Clinical Trials Network
    43. 54. spontaneous <ul><li>Methods of ventilation that allow the patient to breathe spontaneously are thought to be advantageous. </li></ul><ul><li>Modern ventilators have sensitive triggers and flow patterns that can adapt to the patient’s needs, thus reducing the work of breathing. </li></ul>
    44. 55. Synchronised intermittent mandatory ventilation <ul><li>set number of breaths are delivered by the ventilator and the patient can breathe between these breaths. This method is often used during weaning, often with pressure support, by which the ventilator enhances the volume of each spontaneous breath up to a predetermined positive pressure. </li></ul>
    45. 56. Biphasic airway pressure <ul><li>similar to continuous positive airways pressure ventilation but pressure is set at two levels. The ventilator switches between the levels, thus augmenting alveolar ventilation. </li></ul>
    46. 60. 37 years old ,75 kg , had been suffered of car accident , intubated and ventilated , Gcs=7 3days later you have been called for consultation Ventilator setting
    47. 61. <ul><li>Fio2 = 0.8 </li></ul><ul><li>Pao2= 60 </li></ul><ul><li>Paco2=25 </li></ul><ul><li>What is your differential diagnosis ? </li></ul><ul><li>What is your final diagnosis. </li></ul>
    48. 62. Ventilator <ul><li>Mode ippv cmv </li></ul><ul><li>Vt = 750 </li></ul><ul><li>F = 12 </li></ul><ul><li>PEEP = 5 </li></ul><ul><li>Flow = 27 lit/min </li></ul><ul><li>PIP = 50 </li></ul><ul><li>Patient = fighting </li></ul><ul><li>What is your suggestion ? </li></ul>
    49. 63. Mode of ventilation
    50. 64. Ventilation Pressure Support <ul><li>Improved alveolar recruitment </li></ul><ul><li>Reduced shunt and deadspace ventilation </li></ul><ul><li>Improved venous r eturn </li></ul><ul><li>Shorter p ostoperative recovery phase , fewer cases of nausea/vomiting </li></ul><ul><li>Optimal support of breathing and no fighting against the v entilator </li></ul>Spontan eous breathing equals
    51. 65. Vt
    52. 66. F
    53. 67. PEEP
    54. 68. Flow
    55. 69. PIP
    56. 70. Recruitment
    57. 71. Inspiratory time
    58. 72. Spontaneous + PSV =No fight
    59. 73. Preparation for weaning from the ventilator <ul><li>Ensure </li></ul><ul><li>x Clear airway </li></ul><ul><li>x Adequate oxygenation </li></ul><ul><li>x Adequate carbon dioxide clearance </li></ul><ul><li>Control of </li></ul><ul><li>x Precipitating illness </li></ul><ul><li>x Fever and infection </li></ul><ul><li>x Pain </li></ul><ul><li>x Agitation </li></ul><ul><li>x Depression </li></ul><ul><li>Optimisation of </li></ul><ul><li>x Nutritional state </li></ul><ul><li>x Electrolytes (potassium, phosphate, magnésium) </li></ul><ul><li>Beware </li></ul><ul><li>x Excessive carbon dioxide production from overfeeding </li></ul><ul><li>x Sleep deprivation </li></ul><ul><li>x Acute left heart failure </li></ul>
    60. 75. Obstructive lung disease <ul><li>COPD </li></ul><ul><li>Asthma </li></ul>
    61. 76. Indications for NIV for AE-COPD GOLD 2005
    62. 77. Exclusion criteria GOLD 2005
    63. 78. Indications for Invasive Mechanical Ventilation GOLD 2005
    64. 79. Think twice <ul><li>Reversibility of the precipitating event, </li></ul><ul><li>Patient’s/relative’s wishes, and </li></ul><ul><li>Availability of intensive care facilities </li></ul><ul><li>Failure to wean </li></ul>Mortality among COPD patients with respiratory failure is no greater than mortality among patients ventilated for non-COPD causes GOLD 2005
    65. 80. Post-Intubation hypotension <ul><li>Reduced venous return secondary to positive intrathoracic pressure due to bagging </li></ul><ul><li>Direct vasodilation and reduced sympathetic tone induced by sedative agents </li></ul>
    66. 81. Mechanical ventilation <ul><li>Avoid overcorrection of respiratory acidosis and life threatening alkalosis. </li></ul><ul><li>Prolonged expiratory time. I:E – 1:2.5 to 1:3. </li></ul><ul><li>Low Respiratory Rate- 10-14/mt. </li></ul><ul><li>Limited tidal volume </li></ul>
    67. 82. PEEP <ul><li>PEEPe beneficial </li></ul><ul><ul><li>Reduce gas trapping by stenting open the airways </li></ul></ul><ul><ul><li>Reduce the work to trigger inspiratory flow </li></ul></ul><ul><li>As PEEPe is applied, tidal volume will increase without an increase in airway pressure until PEEPe exceeds PEEPi </li></ul>
    68. 83. Post extubation NIV <ul><li>Allow early extubation </li></ul><ul><li>Prevent post extubation respiratory failure </li></ul>
    69. 84. Asthma
    70. 85. NIV in asthma <ul><li>Few trials </li></ul><ul><li>Trial of NIV over 1–2 hours in an ICU if there are no contraindications </li></ul>
    71. 86. NIV in acute bronchial asthma <ul><li>FEV1<40%, PaCO2 <40mm Hg </li></ul><ul><li>Conventional medical management Vs BiPAP 15/5 for 3 hours </li></ul>Chest. 2003;123
    72. 87. NIV in asthma…. <ul><ul><li>80% NIV group increased FEV1 by >50% as compared to baseline, vs 20% of control patients (p < 0.004) </li></ul></ul><ul><ul><li>alleviate the attack faster, and </li></ul></ul><ul><ul><li>significantly reduce the need for hospitalization. </li></ul></ul>
    73. 88. Endotracheal intubation <ul><li>Absolute indications </li></ul><ul><ul><li>Cardiopulmonary arrest and </li></ul></ul><ul><ul><li>Deteriorating consciousness </li></ul></ul><ul><li>Relative </li></ul><ul><ul><li>Progressive deterioration, hypercapnia with increasing distress or physical exhaustion </li></ul></ul>
    74. 89. <ul><li>Intubation performed/supervised by experienced anaesthetists or intensivists </li></ul><ul><li>Use larger endotracheal tube </li></ul>
    75. 90. • FiO 2 = 1.0 (initially) • Long expiratory time (I:E ratio >1:2) • Low tidal volume 5–7 ml/kg • Low ventilator rate (8–10 breaths/min) • Set inspiratory pressure 30–35 cm H2O on pressure control ventilation or limit peak inspiratory pressure to <40 cm H2O • Minimal PEEP <5 cm H2O
    76. 91. Aerosol delivery <ul><li>Metered dose inhaler (MDI) system </li></ul><ul><li>• Spacer or holding chamber </li></ul><ul><li>• Location in inspiratory limb rather than Y piece </li></ul><ul><li>• No humidification (briefly discontinue) </li></ul><ul><li>• Actuate during lung inflation </li></ul><ul><li>• Large endotracheal tube internal diameter </li></ul><ul><li>• Prolonged inspiratory time </li></ul>
    77. 92. <ul><li>Jet nebuliser system </li></ul><ul><li>• Mount nebuliser in inspiratory limb </li></ul><ul><li>• Consider continuous nebulisation </li></ul><ul><li>• Increase inspiratory time and decrease respiratory rate </li></ul><ul><li>• Use a spacer </li></ul><ul><li>• Stop humidification </li></ul><ul><li>• Delivery may be improved by inspiratory triggering </li></ul>
    78. 93. Ventilator strategies in Bronchopleural fistula
    79. 94. <ul><li>Air escaping through the BPF </li></ul><ul><ul><li>delays healing of the fistulous track </li></ul></ul><ul><ul><li>significant loss of tidal volume, jeopardizing the minute ventilation and oxygenation </li></ul></ul>
    80. 95. Measures to reduce air-leak <ul><li>Limit the amount of PEEP </li></ul><ul><li>Limit the effective tidal volume, </li></ul><ul><li>Shorten inspiratory time, </li></ul><ul><li>Reduce respiratory rate. </li></ul><ul><li>Use of double-lumen intubation with differential lung ventilation, </li></ul>
    81. 96. Chest tube <ul><li>To add positive intrapleural pressure during the expiratory phase to maintain PEEP </li></ul><ul><li>Occlusion during the inspiratory phase to decrease BPF flow </li></ul>
    82. 97. High-frequency ventilation (HFV) <ul><li>Useful in patients with normal lung parenchyma and proximal BPF </li></ul><ul><li>Limited value in patients with distal disease and parenchymal disease. </li></ul>