Mechanical Ventilation ppt.pptx including indications, types

mechanical ventilation, definition, indications, types, modes, patient management

1. Mechanical Ventilation

2. Introduction Mechanical ventilation is the process by which the FIO2 (21% [room air] or more) is moved in and out of the lungs by a mechanical ventilator. Mechanical ventilation is not curative. It is a means of supporting patients until they recover the ability to breathe independently.

3. Indications for mechanical ventilation include Airway compromise due to disease   O btunded such as those from trauma or oropharyngeal infection. A irway obstruction can experience either proximal (such as angioedema) or distal issues (such as asthmatic bronchospasm or acute exacerbation of chronic obstructive pulmonary disease or COPD). Hypoventilation : Impaired central drive (such as drug overdose) Respiratory muscle weakness (such as muscular dystrophy and myositis) Peripheral nervous system defects (such as Guillain-Barré syndrome or myasthenic crisis) Restrictive ventilatory defects (such as chest wall trauma or disease or massive pneumothorax or effusion)

4. Continued.. Hypoxemic respiratory failure Alveolar filling defects (such as pneumonia, acute respiratory distress syndrome (ARDS), or pulmonary edema) Pulmonary vascular defects leading to ventilation-perfusion mismatch (such as massive pulmonary embolism or air emboli) Diffusion defects (such as advanced pulmonary fibrosis)

5. Types of ventilation

6. Types of Mechanical ventilation The 2 major types of mechanical ventilation are negative pressure and positive pressure ventilation Negative pressure ventilation involves the use of chambers that encase the chest or body and surround it with intermittent subatmospheric (or negative) pressure. The “iron lung” was the first form of negative pressure ventilation. It was developed during the polio epidemic. Intermittent negative pressure around the chest wall pulls the chest outward, reducing intrathoracic pressure. Air rushes in via the upper airway, which is outside the sealed chamber. Expiration is passive.

7. Positive Pressure Ventilation Positive pressure ventilation (PPV) is the main method used with acutely ill patients During inspiration the ventilator pushes air into the lungs under positive pressure. Unlike spontaneous ventilation, intrathoracic pressure is raised during lung inflation rather than lowered. Expiration occurs passively as in normal expiration. There are 2 categories of PPV: volume and pressure ventilation.

8. Non invasive ventilation At times, patients may need ventilator support, without the placement of an ET tube. Noninvasive ventilation (NIV) uses a mask, instead of an ET tube, to oxygenate and ventilate a patient. These masks can be full face or a nasal piece. There are 2 common modes used for NIV.

9. Indications of NIV BiPAP for acute or acute-on-chronic respiratory acidosis secondary to COPD exacerbation where pH </= 7.35 BiPAP is the prevention of endotracheal intubation and mechanical ventilation in a patient that is not immediately deteriorating BiPAP or continuous positive airway pressure (CPAP) for cardiogenic pulmonary edema Early NIV for immunocompromised patients with ARF Post-operative ARF As palliation to dyspneic patients in the setting of terminal cancer or other terminal conditions Chest trauma patients with ARF Prevention of post- extubation respiratory failure in high-risk patients

10. Contraindications Absolute Respiratory arrest / need for immediate intubation Facial trauma / burns / surgery / abnormalities Fixed upper airway obstruction Severe vomiting Acute severe asthma Pneumothorax (unless chest drain inserted) Confirmed wish by the patient not to receive NIV in the event of a deterioration.

11. Relative contraindications: Inability to protect airway Life-threatening hypoxaemia Haemodynamic instability Impaired consciousness Confusion / agitation Bowel obstruction Recent facial / upper airway or upper GI tract surgery Copious respiratory secretions Pneumonia

12. Continuous positive airway pressure (CPAP) Restores functional residual capacity (FRC) and is similar to positive end-expiratory pressure (PEEP). However, the pressure in CPAP is delivered continuously during spontaneous breathing, preventing the patient’s airway pressure from falling to o During inspiration, we generate 1 to 2 cm H2O of negative pressure. This reduces airway pressure to 3 or 4 cm H2O. CPAP is often used to treat obstructive sleep apnea. It is a noninvasive modality, delivered through a tight fitting face mask, nasal mask, or nasal pillows. CPAP increases work of breathing (WOB) because the patient must forcibly exhale against the CPAP. Therefore it must be used with caution in patients with myocardial compromise.

13. BiPAP In addition to O2, bilevel positive airway pressure (BiPAP) provides 2 levels of positive pressure support: higher inspiratory positive airway pressure and lower expiratory positive airway pressure. Like CPAP, the patient must be able to spontaneously breathe and cooperate with this treatment BiPAP is used for COPD patients with HF and acute respiratory failure and for patients with sleep apnea. Its use after extubation can help prevent reintubation.

14. Volume Ventilation With volume ventilation, a predetermined VT is delivered with each inspiration. The amount of pressure needed to deliver the breath varies based on compliance and resistance factors of the patient ventilator system. So, the VT is consistent from breath to breath, but airway pressures vary.

15. Pressure Ventilation With pressure ventilation, the peak inspiratory pressure is predetermined. The VT delivered to the patient varies based on the selected pressure and compliance and resistance factors of the patient ventilator system. Careful attention must be given to the VT to prevent unplanned hyperventilation or hypoventilation.

16. Settings in ventilator

17. Settings Tidal volume (V T ): The tidal volume is usually determined based on ideal or predicted body weight (PBW) rather than actual weight. In conditions such as ARDS that require a protective lung strategy, the V T  is set at a low range of 4 to 8 mL/kg PBW. Respiratory rate (RR): The respiratory rate is typically between 12 and 16 breaths per minute. A higher respiratory rate (up to 35 breaths per minute) may be selected to achieve sufficient minute ventilation, especially during a protective lung strategy in ARDS to prevent severe hypercapnia or counteract severe acidosis.

18. Setting Inspiratory flow rate (IFR): The inspiratory flow rate is usually set between 40 and 60 L/min to achieve an inspiratory and expiratory ratio of 1:2 or 1:3. This higher rate allows for longer expiratory time to empty the lungs, targeting an inspiratory-to-expiratory ratio (I:E) greater than 1:3. Fraction of inspired oxygen (FiO 2 ): FiO 2  should be adjusted to the minimum level necessary to maintain a pulse oximetry (SpO 2 ) reading of 90% to 96%. Avoiding hyperoxemia is crucial, as studies have demonstrated an increase in mortality among critically ill patients with excessive oxygen levels. Positive end-expiratory pressure (PEEP):  PEEP increases the functional residual capacity and prevents the collapse of alveoli Initially, the PEEP level is typically set at 5 cm H 2 O and adjusted based on the patient's underlying condition and oxygenation requirements.

19. Trigger sensitivity: Triggers can be categorized into 2 types—flow trigger and pressure trigger. Pressure triggers are typically set at -2 cm H 2 O but should be avoided if auto-PEEP is suspected. In such cases, flow triggers should be used and set at a threshold of 2 L/min

20. Continued.. PAC mode:  The following parameters must be adjusted on the ventilator when using PAC mode: Inspiratory pressure (Pi): T he inspiratory pressure level is usually set between 10 and 20 cm H 2 O, based on the patient's underlying condition to achieve adequate V T . Inspiratory time (Ti): Inspiratory time is typically set to 1 second and adjusted to achieve an I:E ratio of 1:2 to 1:3. PEEP and FiO 2  settings are selected similarly to VAC mode

21. SIMV/PSV mode:  When SIMV/PSV mode is selected, the initial settings include the following: Pressure support (PS): The pressure support typically ranges from 5 to 15 cm H 2 O for spontaneous breaths initiated by the patient above the set rate. It can be adjusted as needed to maintain certain minute ventilation.  Tidal volume (V T ): The tidal volume is set similarly to VAC mode

22. Clinical strategies for ventilator management Lung-Protective Strategy The lung-protective strategy is recommended for patients at risk of developing acute lung injury or progressing to ARDS. This approach involves using low tidal volume ventilation This method is used to prevent barotrauma, volume trauma, and atelectatic trauma. Patients with conditions such as pneumonia, severe aspiration, pancreatitis, and sepsis are examples of those at risk and should be treated using the lung-protective strategy.  A tidal volume (V T ) of 6 mL/kg based on ideal body weight is recommended

23. Continued.. ARDSnet PEEP/FiO 2  protocol:  After initiating mechanical ventilation, it is essential to regularly reassess its effects on the patient, particularly on the alveoli. This assessment involves monitoring the plateau pressure and driving pressure. The plateau pressure reflects the pressure exerted on small airways and alveoli and should ideally be maintained below 30 to avoid volume trauma and lung injury resulting from alveolar overdistension. An inspiratory pause must be initiated to measure the plateau pressure.

24. Obstructive strategy: Extending the expiratory phase to allow for a complete exhalation can reduce auto-PEEP and dynamic hyperinflation when managing the ventilator for an obstructive patient. Most patients require deep sedation to avoid over-breathing the ventilator and excessive inspiratory efforts. Tidal volume (V T ) should be set to 8 mL/kg, while the initial respiratory rate (RR) should be set at 10 breaths per minute.

25. Troubleshoot

26. Ventilator bundles Ventilator bundles are crucial in preventing ventilator-associated events

27. NURSING DIAGNOSES Based on the assessment data, the patient’s major nursing diagnoses may include: • Impaired gas exchange related to underlying illness, or ventilator setting adjustment during stabilization or weaning. Ineffective airway clearance related to increased mucus pro duction associated with continuous positive-pressure mechanical ventilation Risk for trauma and infection related to endotracheal intubation or tracheostomy Impaired physical mobility related to ventilator dependency