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![Low tidal volume ventilation (LTVV)
Benefit
-The multicenter ARMA trial randomly assigned 861 mechanically
ventilated patients with ARDS to receive LTVV (initial tidal volume of 6
mL/kg predicted body weight [PBW]) or conventional mechanical
ventilation (initial tidal volume of 12 mL/kg PBW) .
The LTVV group had a lower mortality rate (31 versus 40 percent) and
more ventilator-free days (12 versus 10 days).](https://image.slidesharecdn.com/ardsandventilatormanagement-180704084743/75/Ards-and-ventilator-management-18-2048.jpg)
![Mode of ventilation
- In order to adhere to a strategy of LTVV, it is probably
easier to use a volume limited approach. However, a pressure
limited mode is an acceptable alternative, as long as the
resulting tidal volumes are stable and consistent with the
strategy of LTVV.
-Regardless of whether volume limited or pressure limited
ventilation is chosen, fully supported modes of mechanical
ventilation (eg, assist control) are generally favored over
partially supported modes (eg, [SIMV]). This is particularly
true early in the course of disease.
-Ultimately, the choice of mode depends primarily on clinician
comfort and familiarity.](https://image.slidesharecdn.com/ardsandventilatormanagement-180704084743/75/Ards-and-ventilator-management-33-2048.jpg)
Uploaded byAmr Elsharkawy
Ards and ventilator management
The document discusses the case of a 27-year-old postpartum woman presenting with worsening dyspnea and hypoxia. It then reviews the key considerations and management strategies for acute respiratory distress syndrome (ARDS), including low tidal volume ventilation, open lung strategies using recruitment maneuvers and high positive end-expiratory pressure, unconventional approaches like airway pressure release ventilation and high frequency oscillatory ventilation, and adjunctive therapies such as prone positioning. The optimal ventilator mode, settings, and adjunctive strategies depend on the individual patient's severity of lung injury and response to different interventions.
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Ards and ventilator management
- 1. ARDS and Ventilator Management AmrMohamed Elsharkawy Critical care medicine department Alexandria University
- 2. 27-year-old woman withdyspnea • 4 days s/p C-section • Gradual increase in dyspnea over 24 hours with fever of 101 • Evaluation – Crackles R > L – No peripheral edema – Hypoxia (7.25/67/41 on 40% VM) – Normal Echo
- 6. 27-year-old woman withdyspnea • Clinical Course – FiO2 100%; PEEP 20 cm H2O – Peak and plateau airway pressures: 40s
- 7. 27-year-old woman withdyspnea • Clinical Course – FiO2 100%; PEEP 20 cm H2O – Peak and plateau airway pressures: 40s • Key questions – What is the cause of acute respiratory failure? – How to oxygenate the patient? – How to save her life?
- 8. Common Causes ofHypoxemic Respiratory Failure Acute lung injury (ALI) / ARDS Pulmonary Edema Diffuse alveolar Hemorrhage Pulmonary Embolism Interstitial lung disease Pneumonia Neoplasm Pulmonary contusion Atelectasis COPD Asthma Bronchiolitis
- 10. ARDS: Berlin Definition JAMA2012;307:2526-33 Category Criterion Timing Within 1 week of clinical insult or new/worsening respiratory sx Chest Imaging Bilateral opacities – not fully explained by effusions, lobar/lung collapse, or nodules Origin of edema Not fully explained by cardiac failure or fluid overload. Objective measure to rule out hydrostatic edema Oxygenation: Mild 200 mm Hg < PaO2/FIO2 < 300 mm Hg* Oxygenation: Moderate 100 mm Hg < PaO2/FIO2 < 200 mm Hg** Oxygenation: Severe PaO2/FIO2 < 100 mm Hg** * PEEP or CPAP > 5 cm H2O; ** PEEP > 5 cm H2O
- 11. • Di usebilateralff infiltrates – Patchy, confluent – Alveolar, ground--‐ glass • In contrast to CHF, no prominence of.. – Cardiomegaly – Pleural e usionff – Widened vascular pedicle
- 12. ARDS: Chest RadiographCriteria • Radiographic findings not attributable to: – Chronic changes – Atelectasis – Mass – Pleural effusion
- 14. ARDS Management Mechanical Ventilation: • Low tidal volume ventilation • Open lung ventilation • High peep – recruitment • Inverse ratio ventilation •Unconventional approach: • APRV • HFV General Measures: •Prone positioning •Nitric oxide •NMBA •Fluid Management •ECMO
- 15. Strategies of mechanicalventilation of adults in ARDS
- 16. LOW TIDAL VOLUMEVENTILATION - Low tidal volume ventilation (LTVV) is also referred to as lung protective ventilation. - For patients with acute respiratory distress syndrome (ARDS), low tidal volume ventilation (4 to 8 mL/kg predicted body weight) is recommended - Adjust the tidal volume to achieve an inspiratory plateau airway pressure =30 cm H O
- 17. Low tidal volumeventilation (LTVV) Benefit Evidence suggests that the early application of and adherence to LTVV improves mortality, as well as other clinically important outcomes in patients with ARDS
- 18. Low tidal volumeventilation (LTVV) Benefit -The multicenter ARMA trial randomly assigned 861 mechanically ventilated patients with ARDS to receive LTVV (initial tidal volume of 6 mL/kg predicted body weight [PBW]) or conventional mechanical ventilation (initial tidal volume of 12 mL/kg PBW) . The LTVV group had a lower mortality rate (31 versus 40 percent) and more ventilator-free days (12 versus 10 days).
- 19. Low tidal volumeventilation (LTVV) Harm - LTVV is generally well tolerated. - It was not associated with any clinically important adverse outcomes in the ARMA trial. -With respect to physiologic adverse outcomes, LTVV caused hypercapnic respiratory acidosis in some patients. - Hypercapnic respiratory acidosis was an expected and generally well tolerated consequence of LTVV.
- 20. Low tidal volumeventilation (LTVV) Harm - Two major concerns were expressed after publication of the ARMA trial. (1) Auto-PEEP: The higher respiratory rater in LTVV may create auto-PEEP by decreasing the time available for complete expiration (2) sedation: - Work of breathing and patient-ventilator asynchrony may increase when tidal volumes are <7 mL/kg of predicted body weight. - While asynchrony may require increased sedation soon after the initiation of LTVV, the need for increased sedation does not appear to persist
- 21. Low tidal volumeventilation (LTVV) Application
- 22.
- 23. Permissive Hypercapnia - LTVVfrequently requires permissive hypercapnic ventilation (PHV), a ventilatory strategy that accepts alveolar hypoventilation in order to maintain a low alveolar pressure and minimize the complications of alveolar overdistension (eg, ventilator-associated lung injury). - Hypercapnia and respiratory acidosis are a consequence of this strategy. - Minimum accepted PH = 7.25 - The degree of hypercapnia can be minimized by using the highest respiratory rate that does not induce auto-PEEP and shortening the ventilator tubing to decrease dead space
- 24. Open Lung ventilation(OLV) - a strategy that combines low tidal volume ventilation (LTVV) with a recruitment maneuver and subsequent titration of applied PEEP to maximize alveolar recruitment. - The LTVV and set limits on plateau pressure aim to mitigate alveolar overdistension, while the applied PEEP seeks to minimize cyclic atelectasis. - Together, these effects are expected to decrease the risk of ventilator-associated lung injury.
- 25. Open Lung ventilation(OLV) - On balance, most trials do not show convincing benefit and some show possible harm such that it is better to avoid the routine application of open lung strategies as an initial strategy in patients with ARDS. - Any use of OLV strategies should be limited to those with severe ARDS refractory to standard LTVV strategies; in addition, when employed, patients should be closely observed for an oxygenation response, so that the clinician can decide whether it is appropriate to continue or abandon the OLV trial.
- 26. High PEEP - Theroutine use of a high PEEP strategy in ARDS patients as an initial strategy is not recommended. - However, in patients refractory to standard methods of mechanical ventilation, some experts use a high PEEP strategy such as that employed in the ALVEOLI or LOVS trials
- 27. Recruitment maneuvers Approaches Fourdifferent approaches• • Single breath 1.5 – 2 times the set VT is applied every one or two minutes •PEEP is temporarily ++,subsequent end inspiratory volume is ↑ •VT can be raised temporarily •High levels of CPAP applied for set point of time •RM can be applied with PCV 20cmH2O and PEEP 30- 40cmH20 for 1-2min Karmarek RM strategies to optimize alveolar recruitment. Curr.
- 28. Aggressive RMS • CT imagesshowed improvement in • collapse lung Better oxygenation ↓ mortality Amato MB et al : N Engl J Med 1998:338; 345-54
- 29.
- 30. High PEEP - Itis thought that use of higher levels of PEEP benefit patients by opening collapsed alveoli, which in turn serves to decrease alveolar overdistension because the volume of each subsequent tidal breath is shared by more open alveoli. - If the alveoli remain open throughout the respiratory cycle, cyclic atelectasis is also reduced. Alveolar overdistension and cyclic atelectasis are the principal causes of ventilator-associated lung injury.
- 31. High PEEP - Theapplication of high PEEP does not appear to be associated with improved mortality except perhaps in those with severe gas exchange abnormalities. - Further study is needed to determine the optimal level of PEEP and the ARDS population in whom a clear mortality benefit might be expected
- 32. Mode of ventilation -Patients with ARDS can be supported using either a volume limited or a pressure limited mode of Ventilation -In most patients with ARDS, a volume limited mode will produce a stable airway pressure and a pressure limited mode will deliver stable tidal volumes, assuming that breath to breath lung mechanics and patient effort are stable. - Abrupt changes in the airway pressure in a patient receiving volume limited ventilation, or in tidal volumes in a patient receiving pressure limited ventilation, should prompt an immediate search for a cause of an acute change in compliance (eg, pneumothorax or an obstructed endotracheal tube).
- 33. Mode of ventilation -In order to adhere to a strategy of LTVV, it is probably easier to use a volume limited approach. However, a pressure limited mode is an acceptable alternative, as long as the resulting tidal volumes are stable and consistent with the strategy of LTVV. -Regardless of whether volume limited or pressure limited ventilation is chosen, fully supported modes of mechanical ventilation (eg, assist control) are generally favored over partially supported modes (eg, [SIMV]). This is particularly true early in the course of disease. -Ultimately, the choice of mode depends primarily on clinician comfort and familiarity.
- 34.
- 35. Inspiratory time adjustment (Inverseratio ventilation) - Refractory hypoxemia can occur even if the applied PEEP and FiO2 are optimized. In this situation, increasing the I:E ratio by prolonging inspiratory time may improve oxygenation. -Increasing the I:E ratio will increase the mean airway pressure and may improve oxygenation in some patients.
- 36. Inspiratory time adjustment (Inverseratio ventilation) - There are potential costs associated with prolonging the inspiratory time that should be considered. When the inspiratory time is increased, there is an obligatory decrease in the expiratory time. This can lead to air trapping, auto-PEEP, barotrauma, hemodynamic instability, and decreased oxygen delivery. - In addition, a prolonged inspiratory time may require significant sedation or neuromuscular blockade, particularly if the inspiratory time surpasses the expiratory time (inverse ratio ventilation).
- 37.
- 38. ARDS –Unconventional approaches: • AirwayPressure Release Ventilation (APRV) • High frequency oscillatory ventilation (HFOV)
- 39.
- 40. Airway Pressure ReleaseVentilation • Can minimize lung volume • • expansion Inflation pressure is CPAP level – Best compliance , oxygenation APRV supports ventilation at optimal resting volumes • Pulmonary volume is maximized at FRC
- 41. Airway Pressure ReleaseVentilation • APRV used in patients with lung injury • • • • • • Improved haemodynamics Reduced peak and mean airway pressures Decreased use of sedatives and relaxants Improved cardiac index Pressor agents usage is reduced Shortened the length of mech ventilation Kaplan et al , Crit Care 2001,5(4) ;221-226
- 42. Prone position inARDS Proposed Explanations • • • • Increased FRC Blood Flow Redistribution Changes in Diaphragmatic Motion Improved Secretion Removal
- 43.
- 44. Prone Positioning: Procedure • Appropriatestaff to manage patient and “tubes”. • • • Minimize abdominal pressure. Maintain pt in Swimming position (one arm extended over head, head turned to that side) Sedation generally required.
- 45. Prone Positioning: How Long? Fridrichet al, Anesth Analg 1996;83:1206-1211
- 46. Prone Position • Prone-SupineStudy Group • • • • Multicenter randomized clinical trial 304 adult patients prospectively randomized to 10 days of supine vs. prone ventilation 6 hours/day Improved oxygenation in prone position No improvement in survival NEJM 2001;345:568-73
Editor's Notes
- #3 Let me start my talk with a case….
- #4 27 yo female, 4 days post c-section, progressive shortness of breath, normal echo, mild hypertension, no peripheral edema, fever to 101, PCWP 15 on high PEEP subsequently, right sided crackles.
- #5 27 yo female, 4 days post c-section, progressive shortness of breath, normal echo, mild hypertension, no peripheral edema, fever to 101, PCWP 15 on high PEEP subsequently, right sided crackles.
- #6 27 yo female, 4 days post c-section, progressive shortness of breath, normal echo, mild hypertension, no peripheral edema, fever to 101, PCWP 15 on high PEEP subsequently, right sided crackles.
- #9 There are many reasons to have respiratory failure as you know But REALLY the majority of my focous would be ARDS A LITTLE ABOUT DEFINITION, epidemiology, pathophysiology . But most on management which has impact on your practice.
- #10 So how does ARDS work? Something trigger, this trigger can either directly injure the alveolo-capillary interface the classic example is asp. PNA, or indirectly through systemic inflammatory process hit the lung like any other systems, the heart brain, kidneys,…also hit the lung and cause a-c injury. The confusing issue is this injured lung can produce more inflammatory markers going out of the lung and cause systemic inflammation elsewhere in the body. So direct and indirect injury and feed back from lung potentiating the systemic inflammation causing permeability edema, surfactant is not low but is not working, cap. Thrombi, which all result is stiff lung, hypoxia….
- #11 So they came up with new definition called Berlin definition , which is very similar to old one except three new changes: 1-the pulmonary capillary wedge pressure criterion has been removed, 2-the term “acute lung injury” has been eliminated, 3- and minimal ventilator settings have been added.
- #12 A few quick comments about chest radiographs. This is a typical appearance It is diffuse bil can be patchy, ggo, importantly, we do not see cardiomegaly….. Having said that you can have both together , having chf and ARDS together. So you need to be aware. But classically pure ARDS doesnot have that component.
- #14 As we look at the ct though, you can get a better picture of where densities are. When u look at cxr it looks more homogenous but in ct you see the density follow gravity.
- #15 2- and general measures to improve oxygentation and or outcome including ….
- #21 Breath stacking is a manifestation of asynchrony that can occur despite deep sedation [16]. It causes episodic delivery of higher tidal volumes, which may undermine the benefits of LTVV. Frequent breath stacking (more than three stacked breaths/min) can be ameliorated by delivering slightly higher tidal volumes (7 to 8 mL/kg PBW), as long as the plateau airway pressure remains less than 30 cm H O, or by administering additional sedation.
- #39 So these are conventioanl approach, low tv , low plt and peep how about non conventional approaches. sLet’s talk about gas exchange and lung protective startegies. Vent mgm: start with 6 ml/kg ibw u can go up to 8 while keeping plat &lt;30. the caveat is if u have a morbidly obese or significant intraabdominal path can accept higher plt. These are unconventioanl approaches, I will touch on later.
- #40 Long I time, short E time strategy. And spontanous breath allowed throughout the cycle. Long I time let more time to more units open up , increase mean airway pressure without set vol .
- #48 If you make pt in prone position the density will follow the gravity.. Imagine lung is like a wet sponge sitting on table, most of lower part will be collapsed and more wet.