22 09-12 how do i ventilate normal lung


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Ventilation,Normal lung,more art than science

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  • Intensive care medicine was born along with art and science of positive pressure ventilation. Started with polio epidemic in 1952,denmark,3000 patient required critical care and 1/3 had paralysis had 10 % had respiratory insufficency,ventilation done with –negative pressure bulk flow mobilization in patient lung by cyclically creating sub atmospheric pressure around the chest or cuirass ventilator rigid shell around the chest,logistic problems of nursing care, mortality was 87% dr Lassen and dr Bjorn Ibsen invented tracheotomy and positive pressure ventilation and mortality dropped to 40%
  • CNS- depressant drug,structural brain damage, spinal cord disease above c5,GBS,MG,Critical illness poly neuropathy,organophosphates,amytropic lateral sclerosis, anterior horn cell disease,ms dytrophy,periodic paralysis,myopathy dyselectrolemia,ks.120,cardiac support in shock,as part of general anesthesia,marked airway or facial odema
  • The first positive-pressure ventilators were designed to inflate the lungs until a preset pressure was reached. This type of pressure-cycled ventilation fell out of favor because the inflation volume varied with changes in the mechanical properties of the lungs. In contrast, volume-cycled ventilation, which inflates the lungs to a predetermined volume, delivers a constant alveolar volume despite changes in the mechanical properties of the lungs. For this reason, volume-cycled ventilation has become the standard method of positive-pressure mechanical ventilation
  • 22 09-12 how do i ventilate normal lung

    1. 1. How do I ventilate normal lung? Dr Anand.Tiwari F.N.B Critical care medicine. Consultant neuro-intensive care Ruby hall clinic
    2. 2. History 2012 1950
    3. 3. When do I ventilate a normal lung? Brainstem Spinal cord Nerve rootAirway Nerve Neuromuscular junction Respiratory muscle Lung Pleura Chest wall EXTRAPULMONARY Components
    4. 4. Choosing the interface
    5. 5. Increased vascular resistance Decreased venous return Decreased distensibility Decreased distensibility Decreased venous return Alveoli Septal displacement Heart- Lung Interaction Physiology
    6. 6. Volume / Compliance Flow x Resistance Pressure=flow x resistance Alveolar pressure=volume/compliance + PEEP Airway pressure=Flow x Resistance + volume/compliance + PEEP Flow=volume/time B (P A LV)A (P AW) Physics of Positive pressure ventilation
    7. 7. 3 key ventilator phase variables When the breath is delivered What limits gas delivery what end the gas delivery Trigger Limit cycle
    8. 8. Assisted Mode (Volume-Targeted Ventilation) Time (sec)Time (sec) Flow (L/m) Pressure (cm H2O) Volume (mL) Preset VT Volume Cycling Patient triggered, Flow limited, Volume cycled Ventilation
    9. 9. Assisted Mode (Pressure-Targeted Ventilation) Pressure Flow Volume (L/min) (cm H2O) (ml) Set PC level Time (sec)Time (sec) Time-Cycled Patient Triggered, Pressure Limited, Time Cycled Ventilation
    10. 10. SIMV +PS
    11. 11. Pressure support
    12. 12. Physiological PEEP
    13. 13. Case scenario!! • 25 yr old female admitted with history of BZD and antidepressant,no past medical history in. Registrar calls you in evening 7p.m patient is unwell gurgling sounds, mild airway obstruction drowsy .Respiration appears shallow ? • U advise -ABG ? • NIV ? Invasive ventilation.?
    14. 14. Goals during Positive pressure ventilation • Adequacy of ventilation • Oxygenation • Decreased work of breathing • Patient comfort • Synchrony with ventilator • Avoiding complication-VILI,VAP • Early wean ability What mode ?? Which setting ??
    15. 15. Settings • Fio2 • R.r • Tidal volume • I:E ratio • Trigger • Peep • Set alarms
    16. 16. Monitoring during ventilation • Pulse oximetry - 95 % • ABG – pH. 7.32 – PCO2- 55 – Po2 414 – HCO3 28 • EtCo2 -50 • Chest x ray Vitals- P-120/min B.p- 90/60 Note—no replacement to a vigilant Intensivist bedside
    17. 17. Hypovolemia
    18. 18. What next? • Wake up call for consultant? • Registrar reports increase in pressure alarm repeatedly ? U Advice • A)Suction • B)Nebulization • C) Chest X ray
    19. 19. PIP vs Pplat NormalNormal High RHigh Rawaw High FlowHigh Flow Low ComplianceLow Compliance Time (sec)Time (sec) Paw(cmHPaw(cmH22O)O) PIPPIP PPPlatPlat PIPPIP PIPPIP PIPPIP PPPlatPlat PPPlatPlat PPPlatPlat Interpretation of Ventilator Graphics v.1 ©2000 RespiMedu
    20. 20. Complications • Related to intubation and extubation. Ventilator related • Extra pulmonary – gut ischemia, Water ADH +
    21. 21. • F • A • S • T • H • U • G anand tiwari Ancillary care Give your patient a fast hug (at least) once a day* Jean-Louis Vincent, MD, PhD, FCCM
    22. 22. Day 3 patient start to wake up trigger ventilator frequently some breath stacking,vitals stable • Restless ,bites the tube intermittently restless • As reported by the nurse and physiotherapist. • You suggest— • A)weaning • B) Sedate and ventilate ABCDE bundle
    23. 23. Mechanical Ventilation Weaning: Predictors (Parameters) • Respiratory Rate < 30/min • Spontaneous Vt > 4 ml/kg • Inspiratory Pressure > - 20 cm H2O • Breathing Index (f/Vt) < 105 • PEEP < 8 cmH2O • PaO2/FIO2 > 200 • FIO2 < .50
    24. 24. Winning modes Esteban, N Engl J Med 1995; 332:345
    25. 25. Summary of recommendations of weaning • Protocol-directed - favorable outcome • SBT or PS trials than-- SIMV • 30min and 120min trials are equally successful • Twice daily SBT no advantage over once daily • Sedation vacation better outcome. • Early compared to late tracheostomy leads to better outcomes
    26. 26. So mechanical ventilation of normal lung should not end up in an abnormal lung… think & act!!!!!!!!