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25- IMV 2 .pptx

  1. Inavsive mechanical ventilation 2 WHO Health Emergencies program (WHE)
  2. WHO Health Emergencies program (WHE) Learning objectives At the end of this lecture, you will be able to: • Manage mechanically ventilated patient with ARDs, Asthma , COPD. • Know Respiratory Care, Setup, & Monitoring.
  3. WHO Health Emergencies program (WHE) Choosing a mode of mechanical ventilation depends on: • The reason it is required. • The underlying disease process. • In general, AC is used as the initial mode for a patient needing invasive mechanical ventilation. Choosing a mode and initial ventilator settings
  4. WHO Health Emergencies program (WHE) A previously healthy 46-year-old woman presents to the hospital and reports a cough, sputum production, and a fever of 4 days’ duration. An admission chest radiograph reveals a developing infiltrate in the left lower lobe. The man is admitted to the general ward and started on antibiotics for community-acquired pneumonia. Less than 24 hours later, the patient continues to deteriorate and requires oxygen at 15 L/min om mask bag. He is not in obvious respiratory distress; however, pulse oximetry reveals severe hypoxemia (83% to 89% on supplemental oxygen, 10 L/min). Sputum cultures pending , and a new chest radiograph reveals new, diffuse bilateral alveolar infiltrates. The patient is intubated because of worsening hypoxemia. • What initial ventilator settings would you use for this patient? • What steps should be taken to minimize barotrauma during ventilation? • What parameters should be measured and monitored? Case study
  5. WHO Health Emergencies program (WHE) ARDS is a heterogenous disease VT diverted from injured units to over distend healthier units Source:
  6. WHO Health Emergencies program (WHE) • The primary goal of mechanical ventilation is to prevent ventilator-induced lung injury (VILI). Mechanical ventilation Source: • Barotrauma e.g., pneumothorax. • Volutrauma. • Atelectrauma. • Biotrauma. • Oxygen toxicity.
  7. WHO Health Emergencies program (WHE) The ventilator settings should be adjusted to ensure adequate gas exchange without causing ventilator-induced lung injury (VILI). The factors that promote VILI are: 1. Hyperinflation during inspiration induced by large VTs and high end-inspiratory pressures. 2. Alveolar collapse during expiration and repeated alveolar opening and closing during each breath promoted by low pressures during expiration. (atelectrauma). 3. Driving pressure (plateau pressure – PEEP) was a major determinant of outcome driving (> 14 cm H2 O was associated with poor outcomes). In addition, , it has been suggested that the mechanical power transferred to the respiratory system from the ventilator plays a key factor in VILI. This means that not only the strain (change in lung volume) but both high flow and respiratory rate are potentially harmful to the lungs. Mechanical ventilation
  8. WHO Health Emergencies program (WHE) Mechanical ventilation Target of mechanical ventilation (lung protective ventilation): 1. Low VTs. 2. High PEEP levels. 3. Strict monitoring of plateau pressure to avoid exceeding 30 cm H2O. Oxygenation: • No studies have shown that increasing PaO2 improves outcome. • SpO2 between 94% and 98% may improve outcomes compared to conventional therapy maintaining SpO2 around 97%.
  9. WHO Health Emergencies program (WHE) VILI can be reduced by Lung protective stratgy
  10. WHO Health Emergencies program (WHE) • Intubation should not be delayed. Respiratory indications: • RR>35-40 breaths/min and there are clinical signs of respiratory distress. • Severe hypoxemia defined as PaO2 < 60 mm Hg or SpO2 < 90% despite high FiO2. • Respiratory acidosis. • Copious secretions. • Other indications for intubation. Non-respiratory indications: • Altered consciousness. • The occurrence of shock. Invasive mechanical vetilation Indications for invasive mechanical ventilation:
  11. WHO Health Emergencies program (WHE) • Volume-controlled ventilation (VCV) is the most commonly used mode of ventilation in ICU. • No data to demonstrate a difference in outcomes between VCV and pressure-controlled ventilation (PCV). • In both VTs and end-inspiratory plateau pressure should be limited and continuously monitored. • The main advantage of VCV is respiratory mechanics monitoring. Which mode of MV is better for ARDS
  12. WHO Health Emergencies program (WHE) 1. VCV How to monitor plateau pressure
  13. WHO Health Emergencies program (WHE) Source: Plateau pressure during pressure control ventilation Simone Sosio , Giacomo Bellani 2019 2. PCV by inspecting the flow signal. If end-inspiratory flow is nil the pressure set at the ventilator in PCV is the plateau pressure. If it is still positive, a resistive pressure is included, which can be calculated by performing an end-inspiratory occlusion manually. The end-inspiratory plateau pressure cannot exceed the set inspiratory pressure in PCV. How to monitor plateau pressure?
  14. WHO Health Emergencies program (WHE) Relation between plateau pressure and mortality rate
  15. WHO Health Emergencies program (WHE) Adjustment of ventilatory settings 1. Adjustment of VT. 2. Adjustment of PEEP. 3. Adjustment of flow rate.
  16. WHO Health Emergencies program (WHE) 1. Adjustment of VT: The VT should be adjusted to 6 ml/kg predicted body weight. It has been shown that a high driving pressure exceeding 14 cm H2 O was associated with poor outcomes. know whether or not VT should be reduced below 6 ml/kg to decrease the driving pressure. To estimate predicted body weight: Males: 50 + 2.3 (height in inches –60) or 50 + 0.91 (height in cm – 152.4). Females: 45.5 + 2.3 (height in inches –60) or 45.5 + 0.91 (height in cm – 152.4).
  17. WHO Health Emergencies program (WHE) • PEEP is the airway pressure at the end of expiration: • recruits atelectatic lung to prevent atelectrauma. • Challenge is in determining “how much PEEP” for the heterogenous ARDS lung. • High PEEP levels around 15 cm H2 O may improve survival in ARD. • The methods used to adjust PEEP in these trials were either to follow a PEEP/FiO2 table or to maintain plateau pressure below 28-30 cm H2O. 2. Adjustment of PEEP:
  18. WHO Health Emergencies program (WHE) • Set PEEP corresponding to severity of oxygen impairment: • Titrate the FiO2 to the lowest value that maintains target SpO2 88–93%. • Set corresponding PEEP, based on individual. • Higher PEEP for moderate-severe ARDS. Source: 2. Adjustment of PEEP:
  19. WHO Health Emergencies program (WHE) • When high PEEP levels are used ,be cautious: • Earlier application of low tidal volume and the appropriate level of PEEP will minimize risk. • Hypotension due to decreased venous return to right heart. • Over-distension of normal alveoli and possible ventilator-induced lung injury and increase in dead space ventilation. 2. Adjustment of PEEP:
  20. WHO Health Emergencies program (WHE) During VCV, flow rate around 60 L/min usually suffices to meet the patient’s ventilatory demand and this setting can be used as a default value. 3. Adjustment of flow rate:
  21. WHO Health Emergencies program (WHE) Mechanical Ventilation in Acute Respiratory Distress Syndrome summary (LPV) Goals: • PaO2: 55-80 mm Hg (7.3-10.7 kPa). • Pplat: ≤30 cm H2O. • VT: 4-6 mL/kg PBW. • pH: >7.15 is acceptable. 1. Start with Assist-Control with VT of 8 mL/kg PBW. 2. Decrease by 1 mL/kg over the next 4 hours until VT of 4-6 mL/kg is reached. 3. If Pplat is >30 cm H2O, decrease VT by 1 mL/kg until VT is 4 mL/kg or arterial pH reaches 7.15. 4. If using VT of 4 mL/kg and Pplat is <25 cm H2O, VT can be increased by 1 mL/kg until Pplat is 25 cm H2O or VT is 6 mL/kg.
  22. WHO Health Emergencies program (WHE) Mechanical Ventilation in Acute Respiratory Distress Syndrome summary (LPV) 5-If a Pplat of ≤30 cm H2O has been achieved with a VT >6 mL/kg and a lower VT is clinically problematic (i.e., need for increased sedation), it is acceptable to maintain the higher VT. 6- Initiation of PEEP in Acute Respiratory Distress Syndrome. • Initiate PEEP at 5 cm H2O and titrate up in increments of 2-3 cm H2O. • Full recruitment effect may not be apparent for several hours. • Monitor blood pressure, heart rate, and PaO2 or pulse oximetry during PEEP titration. • Optimal PEEP settings are typically 8-15 cm H2O.
  23. WHO Health Emergencies program (WHE) A 31-year-old man with a history of asthma is intubated and admitted to the ICU for an acute asthma exacerbation. Peak airway pressure on admission was 42 cm H2O, and Pplat was 24 cm H2O immediately after intubation; however, 6 hours later, peak airway pressures have arisen to 53 cm H2O while the Pplat has remained the same. • What is the likely etiology of her high peak airway pressures in the setting of unchanged plateau pressures? • What adjunctive therapies, in addition to ventilator support, does this patient need to reduce the elevated airway pressures? Case study
  24. WHO Health Emergencies program (WHE) Pathophysiology of acute exacerbation of COPD and asthma • Dynamic hyperinflation. • Respiratory muscle dysfunction. • Inefficient gas exchange. • Cardiovascular abnormalities.
  25. WHO Health Emergencies program (WHE) Failure of the respiratory system to return to the elastic equilibrium volume (PEEPi) In COPD and asthma consequences is sever and may lead to hypotension and can be life-threatening. Causes leading to DH are: • High expiratory airway resistance, combined with expiratory flow limitation. • Low elastic recoil (emphysema). • High ventilatory demands • Short expiratory time due to tachypnoea. Dynamic hyperinflation (DH)
  26. WHO Health Emergencies program (WHE) Consequences of dynamic hyperinflation during acute exacerbation of COPD and asthma • Always consider hyperinflation in the mechanically ventilated patient with hypotension, especially if obstructive lung disease is present. • Briefly disconnect the ventilator and hypotension will rapidly improve
  27. WHO Health Emergencies program (WHE) Airflow obstruction increases the work of breathing • No auto- PEEP (PEEPi). • Minimal inspiratory pressure change required (‘trigger’ work) to initiate inspiration . • With auto- PEEP (PEEPi). • Pressure change required t o initiate inspiration (‘trigger’ work) is evidently increased • Alveolar pressure and flow curves during spontaneous breathing Source : SARI ToolKit 2nd Edition
  28. WHO Health Emergencies program (WHE) • Relieve excessive dyspnoea • Improve gas exchange • Sustain alveolar ventilation • Unload respiratory muscles Mechanical ventilatory goals in Asthma And COPD:
  29. WHO Health Emergencies program (WHE) Non-invasive mechanical ventilation (NIMV) in COPD Physiological effects NIMV failure Decreased work of breathing Counterbalance PEEPi Improve gas exchange. Worsening pH and/or respiratory rate after 2-4 hours of BiPAP therapy Failure to tolerate BiPAP. Deterioration in mental status. Inability to manage secretions. Hypotension. Uncorrected hypoxaemia. No change in both pH and respiratory rate at 2-4 hours.
  30. WHO Health Emergencies program (WHE) Non-invasive mechanical ventilation (NIMV) Physiological effects NIMV failure • May have a direct bronchodilating effect. • Minimise dynamic hyperinflation by offsetting intrinsic PEEP Recruit collapsed alveoli. • Improve ventilation/perfusion mismatch. • Reduces the work of breathing. • Tachypnoea RR >25/min. • Tachycardia 110/min. • Use of accessory muscles of respiration. • Hypoxia with a PF ratio >200 mmHg. • Hypercapnia with PaCO2>45 mmHg / 6kPa. • FEV1 <50% predicted
  31. WHO Health Emergencies program (WHE) Non-invasive mechanical ventilation In COPD and Asthma Practical aspects: • The patient must be seated and reassured. Choose a face mask appropriate for patient’s face shape/size. BiPAP (IPAP/ EPAP) is the preferred initial mode: Titrate PEEP by increments of 1–2 cmH2O according to patient’s comfort (observe and assess ineffective triggering attempts) Titrate IPAP by increments of 2 cmH2O to patient’s comfort, respiratory rate (≤25/min) and tidal volume (6–8 mL/kg), avoid total airway pressure above 20 cmH2O.
  32. WHO Health Emergencies program (WHE) Proposed initial settings in controlled modes in patient with severe obstruction: • Tidal volume <6 mL/kg. • Respiratory rate 10 to 14 per minute. • Inspiratory flow 70 to 100 L/min. • Consider the application of low level of PEEP (<5 cmH2O). Invasive mechanical ventilation
  33. WHO Health Emergencies program (WHE) The main principles to decrease dynamic hyperinflation in patients on controlled modes are: 1. Providing controlled hypoventilation : the most effective measure to DH , Achieved By: • Decreasing dead space (using a heated humidifier (HH) instead of heat and moisture filter) • Decreasing in CO2 production (by avoiding hyperthermia, reduction of carbohydrate intake and providing adequate sedation and analgesia). Decreasing dynamic hyperinflation in patients on controlled modes
  34. WHO Health Emergencies program (WHE) 2. Prolongation of the expiratory time : • Increasing peak inspiratory flows. • Shortening inspiratory time. • Eliminating inspiratory pause time. 3. Decrease resistance to expiratory flows. Decreasing dynamic hyperinflation in patients on controlled modes
  35. WHO Health Emergencies program (WHE) Respiratory Care, Setup, & Monitoring Ventilator Setup (prior to connecting patients) • Inspect all equipment for cleanliness or damage. • Review circuit orientation, filters, & heat & humidification system. • Ensure gas supply connected. • Perform machine self-test with new patient and per manufacture (ensure leak test included). • Confirm initial settings and alarms.
  36. WHO Health Emergencies program (WHE) Respiratory Care, Setup, & Monitoring Ventilator Performance Perform Full Status Check q4h: (PIP, Pplat, VT , FiO2, auto-PEEP, Alarms, SpO2, ETCO2 in addition to routine ICU monitoring). • Evaluate vent & patient within 1h of ventilator settings changes. • Wipe down ventilator with approved disinfection qShift. Contingency Planning • Ensure manual (i.e. bag valve resuscitator) ventilation device is operational and at beside along with a face mask and PEEP valve.
  37. WHO Health Emergencies program (WHE) Respiratory Care, Setup, & Monitoring Pulmonary, Endotracheal Tube & Circuit Hygiene • Check cuff pressure and auscultate q12h to avoid over-inflation/leak (<25 cmH2O); consider 'minimal occluding volume' in peds. • Check inflation of pilot balloon to ensure it remains inflated. • Reposition & secure endotracheal tube with skin checks q12h. • Check ventilator circuit qShift for moisture accumulation (drainage); change circuit only if damaged or gross contamination (Ventilator Associated Pneumonia Prophylaxis -VAP PPx). • Head of bed 30 degrees elevated for pneumonia prophylaxis (VAP PPx). • Oral hygiene with mouthwash & suctioning TID (VAP PPx). • Consider continuous subglottic suctioning or q12h oropharyngeal suctioning (VAP PPx). Source : SARI ToolKit 2nd Edition
  38. WHO Health Emergencies program (WHE) Respiratory Care, Setup, & Monitoring Filters: • All external filters should be inspected >daily (and after nebs). • Replace viral filters as frequently as supplies allow in accord with the manufacturer’s recommendations or if damaged/soiled (may last >1 week) • For turbine & compressor ventilators, external inlet filters & fan filters must be cleaned at least monthly. For ventilators that allow, bacterial/viral filters should be placed proximal to external intake filters. • Minimize instrumental/filter dead space.
  39. WHO Health Emergencies program (WHE) Respiratory Care, Setup, & Monitoring Heat & Humidification: • Active system: must use distilled or sterile water (~>500mL daily) to avoid infectious risk and device damage; can be made on site or purchased; check H2O supply q12-24h. • Passive heat moisture exchanger (HME): Only some HME include pathogen filter capability; Many manufacturers suggest change q24h, but studies show that an unsoiled HME in some circumstances can be used for 3-7 days. Nebs decrease lifespan (and must be given via bypass or with HME removed from circuit). Monitor for signs of an increased resistance (e.g. increase in PIP but no change in Pplat, or a prolonged exp flow). Ensure at least 28-30 mgH2O/L efficiency.
  40. WHO Health Emergencies program (WHE) Ventilator circuit , filter and humidifier locations Source : SARI ToolKit 2nd edition
  41. WHO Health Emergencies program (WHE) Respiratory Care, Setup, & Monitoring Respiratory Specific Monitoring: • Continuous pulse oximetry, if unable then spot check as frequently as possible. • Continuous capnography, if unable then spot check as frequently as possible, especially after major ventilator settings changes. • Auscultation performed routinely with checks. • Skin/Mucosal Assessments qShift.
  42. WHO Health Emergencies program (WHE) Abnormal flow waveforms during volume control ventilation Source : SARI ToolKit 2nd Edition
  43. WHO Health Emergencies program (WHE) Abnormal pressure waveforms during volume control ventilation Source : SARI ToolKit 2nd Edition
  44. WHO Health Emergencies program (WHE) Factors influencing peak airway pressure Source : SARI ToolKit 2nd Edition
  45. WHO Health Emergencies program (WHE) Source : FCCS 7th edition Abnormal pressure waveforms during volume control ventilation
  46. WHO Health Emergencies program (WHE) Complications of Mechanical Ventilation • Ventilator Induced Lung Injury (VILI). • Ventilator Induced Diaphragmatic Dysfunction (VIDD). • Ventilator Associated Pneumonia (VAP).
  47. WHO Health Emergencies program (WHE) Hypotension associated with initiation of mechanical ventilation A. Tension Pneumothorax. B. Hemodynamic consequence of Conversion from Negative to Positive Intrathoracic Pressure : common with dehydration. C. Auto-PEEP. D. D. Acute Myocardial Ischemia/Infarction.
  48. WHO Health Emergencies program (WHE) Summary • During mechanical ventilation, a patient must be closely monitored using the ventilator alarm systems, continuous pulse oximetry, attentive physical assessment, measurement of inspiratory Pplat (as clinically appropriate), and intermittent arterial blood gases and chest radiographs as needed. • Guidelines for initiating mechanical ventilation should be carefully followed, with adjustments made based on patient assessment and monitoring. • High inspiratory plateau pressures are associated with a higher incidence of ventilator-induced lung injury and should be maintained below 30 cm H2O. • Hypotension occurring immediately after initiation of invasive mechanical ventilation should prompt evaluation for tension pneumothorax, decreased venous blood return because of intrathoracic pressure, auto-PEEP, or myocardial ischemia.
  49. WHO Health Emergencies program (WHE) References : Clinical care of severe acute respiratory infections – Tool kit COVID-19 adaptation, update 2022 European Society of Intensive Care Medicine (ESICM) Academy ACE modules Society of Critical Care Medicine Fundamental Critical Care Support course (FCCS 7th Edition). • SARI CLINICAL CARE TRAINING • • • Sosio S, Bellani G. Plateau Pressure during Pressure Control Ventilation. abtpn [Internet]. 2019 Oct. 22 ;6(1):76-7. Available from:

Hinweis der Redaktion

  1. Insp flow (70–100 L/min) at the expense of increasing peak inspiratory pressure (Ppeak)
  2. conversion from –ve to + ve As intrathoracic pressure rises, right atrial pressure rises and the intravascular pressure gradient for return of blood from the large extrathoracic veins into the right heart decreases. As a result, blood return to the heart may be reduced.